2021
126
Lo enzo Vallan
Fluo escen polyme ic ca bon
do s: om syn hesis and
elucida ion o chemical s u u e
owa ds pho oac i e hyb id
ma e ials
Di ec o /es
Beni o Mo aleja, Ana M.
Mase , Wol gang K.
© Uni e sidad de Za agoza
Se icio de Publicaciones
ISSN 2254-7606
Lo enzo Vallan
FLUORESCENT POLYMERIC CARBON DOTS:
FROM SYNTHESIS AND ELUCIDATION OF
CHEMICAL STRUTURE TOWARDS PHOTOACTIVE
HYBRID MATERIALS
Di ec o /es
Beni o Mo aleja, Ana M.
Mase , Wol gang K.
Tesis Doc o al
Au o
2019
Reposi o io de la Uni e sidad de Za agoza – Zaguan h p://zaguan.uniza .es
UNIVERSIDAD DE ZARAGOZA
Escuela de Doc o ado
P og ama de Doc o ado en Ingenie ía Química y del Medio Ambien e
FLUORESCENT POLYMERIC CARBON
DOTS: FROM SYNTHESIS AND
ELUCIDATION OF CHEMICAL
STRUCTURE TOWARDS
PHOTOACTIVE HYBRID MATERIALS
TESIS DOCTORAL
Lo enzo Vallan
2018

CONSEJO SUPERIOR DE INVESTIGACIONES CIENTÍFICAS
(CSIC)
INSTITUTO DE CARBOQUÍMICA
FLUORESCENT POLYMERIC CARBON
DOTS: FROM SYNTHESIS AND
ELUCIDATION OF CHEMICAL
STRUCTURE TOWARDS
PHOTOACTIVE HYBRID MATERIALS
Memo ia p esen ada en el ma co del P og ama de Doc o ado de Ingenie ía
Química y Tecnologías del Medio Ambien e de la Uni e sidad de Za agoza,
pa a op a al g ado de Doc o po :
Lo enzo Vallan
Diciemb e 2018
Di ec o es:
Ana Ma ia Beni o Mo aleja
Wol gang Mase
Ana Ma ía Beni o Mo aleja y Wol gang Mase
In es igado es Cien í icos del Consejo Supe io de
In es igaciones Cien í icas
CERTIFICAN
Que la Memo ia, i ulada
“P epa a ion and in es iga ion o luo escen ca bon do s
and ca bon do s-based ma e ials”
ha sido ealizada bajo nues a di ección en el Ins i u o de
Ca boquimica de Za agoza (CSIC) po D. Lo enzo Vallan,
au o izando su p esen ación.
Y pa a que así cons e, i mamos el p esen e ce i icado en
Za agoza, a 12 de diciemb e de 2018
D . Wol gang Mase
D a. Ana Ma ía Beni o Mo aleja
i
Con en
Aknowledgemen ........................................................................................................................ i
Lis o Figu es .......................................................................................................................... ii
Lis o Schemes ........................................................................................................................ xx
Lis o Tables ........................................................................................................................... xxi
Lis o abb e ia ions and ac onyms ...................................................................................... xxiii
1. LITERATURE OVERVIEW .......................................................................................... 1
1.1. De ini ion o ca bon do s ......................................................................................... 2
1.2. Unde s anding CDs chemical na u e and op ical p ope ies: a ch onological
app oach .............................................................................................................................. 3
1.3. P ecu so s and syn hesis me hods o CDs ............................................................. 14
1.4. Quenching o he CDs luo escence....................................................................... 18
1.5. Toxici y o CDs ...................................................................................................... 22
1.6. Func ionaliza ion o CDs o biomedical applica ions .......................................... 23
1.7. CDs in pho oca alysis and sola cells ..................................................................... 28
1.8. Re e ences .............................................................................................................. 30
2. ELUCIDATION OF THE RELATIONSHIP BETWEEN POLYMER STRUCTURE
AND BLUE FLUORESCENCE OF CARBON DOTS ....................................................... 38
2.1. Abs ac .................................................................................................................. 39
2.2. In oduc ion ............................................................................................................ 39
2.3. Expe imen al Sec ion ............................................................................................. 40
2.4. Resul s and discussion ........................................................................................... 45
2.5. Conclusion ............................................................................................................. 61
2.6. Re e ences .............................................................................................................. 62
3. A VERSATILE METHOD FOR THE CONTROLLABLE ROOM-TEMPERATURE
SYNTHESIS AND IN-SITU FUNCTIONALIZATION OF FLUORESCENT CARBON
DOTS .................................................................................................................................... 65
3.1. Abs ac .................................................................................................................. 66
3.2. In oduc ion ............................................................................................................ 66
3.3. Expe imen al sec ion .............................................................................................. 67
3.4. Resul s and discussion ........................................................................................... 68
3.5. Conclusion ............................................................................................................. 75
3.6. Re e ences .............................................................................................................. 75

4. ELECTRONIC INTERACTIONS IN CDs/MoS2 ELECTROSTATIC COMPLEX .... 77
4.1. Abs ac .................................................................................................................. 78
4.2. In oduc ion ............................................................................................................ 78
4.3. Expe imen al sec ion .............................................................................................. 79
4.4. Ti a ion expe imen ............................................................................................... 89
4.5. Conclusions ............................................................................................................ 94
4.6. Re e ences .............................................................................................................. 95
5. ELECTRONIC INTERACTIONS IN COVALENT CDs-TMDs HYBRIDS .............. 96
5.1. Abs ac .................................................................................................................. 97
5.2. In oduc ion ............................................................................................................ 97
5.3. Expe imen al sec ion .............................................................................................. 98
5.4. Resul s and discussion ......................................................................................... 104
5.5. Conclusions .......................................................................................................... 119
5.6. Re e ences ............................................................................................................ 120
6. GENERAL CONCLUSION AND OUTLOOK ......................................................... 122
6.1. Gene al conclusions ............................................................................................. 123
6.2. Ou look ................................................................................................................ 125
6.3. Conclusiones gene ales ........................................................................................ 127
6.4. Pe spec i a ........................................................................................................... 127
7. ANNEX A ................................................................................................................... 129
7.1. Calcula ion o he hyd odynamic adius .............................................................. 132
7.2. Calcula ion o he Quan um Yield ....................................................................... 133
8. ANNEX B ................................................................................................................... 134
8.1. Abs ac ................................................................................................................ 135
8.2. Syn hesis o CDsA, CDsB and CDsC .................................................................. 135
8.3. Size de e mina ion o CDsA-C ............................................................................ 136
8.4. Op ical p ope ies o CDsA-C.............................................................................. 139
8.5. S uc u e cha ac e iza ion o CDsA-C ................................................................. 141
8.6. Conclusion ........................................................................................................... 143
8.7. De ails o he DFT and TDDFT calcula ions ....................................................... 143
8.8. Re e ences ............................................................................................................ 164
9. ANNEX C ................................................................................................................... 165
9.1. Abs ac ................................................................................................................ 166
i
9.2. Expe imen al sec ion ............................................................................................ 166
9.3. Cha ac e iza ion ................................................................................................... 173
10. ANNEX D ............................................................................................................... 236
10.1. Abs ac ............................................................................................................ 237
10.2. Expe imen al sec ion ........................................................................................ 237
10.3. Resul s and discussion ...................................................................................... 237
11. ANNEX E ................................................................................................................ 239
11.1. Abs ac ............................................................................................................ 240
11.2. Expe imen al pa ............................................................................................. 240
11.3. Resul s and discussion ...................................................................................... 242
11.4. Conclusions ...................................................................................................... 246
LIST OF SCIENTIFIC CONTRIBUTIONS .......................................................................... 247
ii
Lis o Figu es
Figu e 1.1. numbe o publica ions con aining he wo ds “ca bon do s” in he i le om 2008
o 2018, sou ce: Scopus). ........................................................................................................... 4
Figu e 1.2. (le ) TEM images o nanoc ys als and o he ca bonaceous ma e ial, ( igh )
abso p ion and emission o he nanoc ys als, om e . 6). ......................................................... 4
Figu e 1.3. PL emission o PEG1500N passi a ed CDs, exci ed a di e en wa eleng hs ( om
e . 9). .......................................................................................................................................... 5
Figu e 1.4. (a) PL due o he quan um size e ec . The sum o di e en conjuga ed domains
wi h dis inc ene gy band gaps can be esponsible o he obse ed exci a ion-dependen PL
beha io . (b) Oxygen g oups loca ed a he edges o he conjuga ed domains can ac as
localized ene gy aps, which p omo e he adia i e elaxa ion. ................................................ 7
Figu e 1.5. eac ions ha occu du ing he hyd o he mal ea men o ci ic acid and
e hylenediamine owa ds he o ma ion o molecula luo opho es, polyme clus e s and he
ca bonized co e ( om e . 30) (b) IPCA luo opho e and i s op ical p ope ies ( om e . 30). (c)
molecula luo opho e and co e con ibu ions o he abso p ion o CDs ( om e 36). (d) he
hyd o he mal ea men o ci ic acid wi h di e en amines p oduces molecula luo opho es
( om e . 32). .............................................................................................................................. 9
Figu e 1.6. (a) some examples o in e ac ions esponsible o he CEE e ec ( om e . 43). (b)
a luo escen c osslinked copolyme om polye hyleneimine and polylac ic acid ( om e . 40).
.................................................................................................................................................. 10
Figu e 1.7. (a) exci a ion dependen PL om non-conjuga ed c osslinked PEI nanopa icles
( om e . 44), (b) exci a ion independen PL om non-conjuga ed polyamide nanopa icles
( om e . 48). ............................................................................................................................ 11
Figu e 1.8. (a) polyme iza ion and ca boniza ion s ep o ci ic acid-based CDs. (b)
Schema ic ep esen a ion o he emission cha ac e is ics o h ee pho oac i e species p oduced
om he he mal ea men o mix u e o ci ic acid and e hanolamine. Du ing py olysis, he
o ganic luo opho es (blue g oups) a e consumed o he buildup o he ca bonized co e
(black sphe e) so ha he PL componen ha co esponds o he ca bonized co e (black ba s)
inc eases a he expenses o he componen ha a ises om he o ganic luo opho es (blue
ba s) ( om e . 26). ................................................................................................................... 12
Figu e 1.9. (le ) TEM image and ( igh ) plausible agg ega ion pa e n o polyme CDs,
esembling g aphi e la ice ( om e . 48). ................................................................................. 13
Figu e 1.10. disassembled au ocla e eac o . .......................................................................... 16
iii
Figu e 1.11. mic owa e syn hesis o CDs o Ce3+ sensing ( om e . 75). ............................. 16
Figu e 1.12. CDs syn hesis by b anched polye hyleneimine c osslinking. ............................. 17
Figu e 1.13. a) o e lap be ween CDs emission and TNP abso bance, b) CDs emission a
di e en concen a ions o TNP, c) S e n-Volme plo s o di e en ni oa oma ics ( igu es
om e . 79). .............................................................................................................................. 19
Figu e 1.14. FRET be ween CDs and he complex (Co(cys)32+). ........................................... 19
Figu e 1.15. sensing mechanism o phy ic acid based on he PET quenching o CDs by Fe3+
( om e . 60). ............................................................................................................................ 20
Figu e 1.16. illus a ion o he inne il e e ec : while in a) he whole emi ed ligh can each
he de ec o , in b) an addi ional specie is able o abso b i . The esul is he dec ease o he
ou pu emission. ....................................................................................................................... 21
Figu e 1.17. mechanism o he amide bond o ma ion ca alyzed by EDC/NHS. Ca boxylic
acid eac s wi h 1-E hyl-3-(3-dime hylaminop opyl)ca bodiimide hyd ochlo ide (EDC),
o ming an uns able in e media e (1). The addi ion o N-Hyd oxysuccinimide (NHS) cause
he clea age o he EDC bond and a less labile NHS es e is o med (2). Finally an amine is
added (3) and he amide bond is achie ed. .............................................................................. 24
Figu e 1.18. luo escence quenching and eco e y o cyclam- unc ionalized CDs, espec i ely
by Cu2+ and S2- ions ( ials pic u es om e . 80). ..................................................................... 25
Figu e 1.19. sensing mechanism based on he hos -gues in e ac ion o p-ni ophenol and
choles e ol wi h β-cyclodex in- unc ionalized CDs ( om e . 106). ........................................ 26
Figu e 1.20. Me cap osuccinic acid in acid condi ions is used o he CDs unc ionaliza ion.
The as-p oduced nanopa icles a e selec i ely quenched by Ag+ ions ( e . 107). ..................... 27
Figu e 1.21. a) sul onamide bond o ma ion and clea age on CDs om e . 108 and
luo escence dependence. b) selec i i y owa ds selenocys eine (Sec). ................................... 27
Figu e 1.22. illus a ion o he CDs/CdS he e ojunc ion and i s pho oca aly ic ac i i y owa ds
p-ni obenzene ( om e . 110). .................................................................................................. 29
Figu e 1.23. pho o ol aic de ice in which he CDs laye ac s as spec al con e e ( om e .
114). ............................................................................................................................................ 30
Figu e 2.1. Pho og aphs o CDs1, CDs2 and CDs3 in solid and in wa e solu ion (0.5
mg/mL), wi h and wi hou UV i adia ion. .............................................................................. 44
Figu e 2.2. AFM images o CDs1 (a), CDs2 (b), CDs3 (c) and hei espec i e heigh
dis ibu ion (d) in black, blue and ed, espec i ely. The a e age heigh is ound a a ound 1
nm o all he samples. ............................................................................................................. 45
ix
Figu e 2.3. DLS size dis ibu ion o CDs1 (black), CDs2 (blue), CDs3 ( ed). All he samples
show a diame e o abou 1 nm. ............................................................................................... 45
Figu e 2.4. DOSY spec a o CDs1, CDs2, and CDs3. ........................................................... 46
Figu e 2.5. (a) UV/Vis, (b) Exci a ion and emission spec a o CDs1 (black), CDs2 (blue) and
CDs3 ( ed). (c) Emission in CDs1-3 a di e en exci a ion wa eleng hs. ............................... 47
Figu e 2.6. PL decay o CDs1 (black), CDs2 (blue) and CDs3 ( ed). (b) Di e en
concen a ions o CDs1 (black), CDs2 (blue), CDs3 ( ed) and quinine sul a e (cyan), plo ed
by in eg a ed PL in ensi y s. abso bance and i ed o calcula ing he quan um yield,
exp essed in %. ......................................................................................................................... 48
Figu e 2.7. (a) abso bance, (c) emission (λex=370 nm) and (e) luo escence in ensi y o CDs1
a di e en pH. (b) abso bance, (d) emission (λex=370 nm) and ( ) luo escence in ensi y o
CDs1 swi ching epea edly he pH om basic o acidic condi ions and ice- e sa. ............... 49
Figu e 2.8. Mole pe cen ages o C, H, N, O in CDs1, CDs2 and CDs3, and he calcula ed
pe cen ages o he epe i i e uni o he co esponding polyme ic condensa ion p oduc . ..... 50
Figu e 2.9. (a) IR spec a o CDs1 (black), CDs2 (blue) and CDs3 ( ed). .............................. 51
Figu e 2.10. (a) XPS su ey o CDs1 (black), CDs2 (blue) and CDs3 ( ed). (b) C1s, O1s and
N1s spec a o CDs1 (le ), CDs2 (cen e ), CDs3 ( igh ). ........................................................ 52
Figu e 2.11. (a) 1H NMR. (b) APT 13C NMR, (c) 1H-13C HSQC and (d) 1H-13C HMBC
spec a o CDs3. (e) one o he possible chain isome s o he CDs1 epe i i e uni , wi h C and
H assigna ion. ........................................................................................................................... 53
Figu e 2.12. (a) 1H NMR. (b) APT 13C NMR, (c) 1H-13C HSQC and (d) 1H-13C HMBC spec a
o CDs3. (e) one o he possible chain isome s o he CDs2 epe i i e uni , wi h C and H
assigna ion. ............................................................................................................................... 54
Figu e 2.13. (a) 1H NMR. (b) APT 13C NMR, (c) 1H-13C HSQC and (d) 1H-13C HMBC
spec a o CDs3. (e) one o he possible chain isome s o he CDs3 epe i i e uni , wi h C and
H assigna ion. ........................................................................................................................... 55
Figu e 2.14. Op imized molecula s uc u es o (a) wo dime (n = 2) chains and (b) one
decame (n =10) chain. (c) HOMO and (d) LUMO molecula o bi als in ol ed in he
luo escence phenomenon. ....................................................................................................... 57
Figu e 2.15. (a) Rela i e luo escence in ensi y o CDs3 whe e I and Io a e he in ensi ies in
p esence and absence o he me al ions. (b) Emission spec a o a CDs3 wa e solu ion in he
p esence o 1mM concen a ion o Mg2+, Ca2+, Fe3+, Pb2+, Ni2+, Cu2+, Ag2+, Zn2+, Co2+, Hg2+.
.................................................................................................................................................. 60

x
Figu e 2.16. Illus a ion o he CDs o ma ion and o he pho o-induced cha ge ans e
phenomenon. ............................................................................................................................ 61
Figu e 3.1. a) abso p ion spec a o CDs 1a-d. b) emission o CDs 1a-d o di e en
exci a ion wa eleng hs. ............................................................................................................ 71
Figu e 4.1. AFM pic u e and heigh p o ile o CDs 4. ............................................................ 83
Figu e 4.2. DLS size dis ibu ion o CDs 4. ............................................................................ 84
Figu e 4.3. ATR-IR spec um o CDs 4. ................................................................................. 84
Figu e 4.4. H1 NMR o CDs 4. ................................................................................................ 85
Figu e 4.5. UV/Vis. (le ) and emission spec a ( igh , λex=370 nm) o CDs 4. ..................... 85
Figu e 4.6. ATR-IR spec a o 1,2-di hiolane de i a i e 1 ( ed) and MoS2-based ma e ials 2
(black) and 3 (blue). ................................................................................................................. 86
Figu e 4.7. No malized Raman spec a o ex olia ed MoS2 (black) and MoS2-based ma e ials
2 (g ay) and 3 (blue), ob ained upon 514 nm exci a ion. ......................................................... 87
Figu e 4.8. The mog aphs o MoS2-based ma e ial 3. ........................................................... 88
Figu e 4.9. SEM images o MoS2-based ma e ial 3. .............................................................. 88
Figu e 4.10. UV-Vis abso p ion spec a o CDs– 4 upon inc emen al addi ions o (a)
ammonium modi ied MoS2-based ma e ial 3. Inse : Enla gemen o he 300-320 nm egion
whe e he isosbes ic poin is de eloped, (b) MoS2-based ma e ial 2. ...................................... 90
Figu e 4.11. Pho oluminescence i a ion assays o CDs– 4 (20 μg/mL) upon inc emen al
addi ions o (a) posi i ely cha ged MoS2-based ma e ial 3, and (b) neu al MoS2-based
ma e ial 2. Measu emen s we e conduc ed in wa e o samples possessing equal abso bance
a he exci a ion wa eleng h o 370 nm. .................................................................................. 91
Figu e 4.12. S e n-Volme plo o CDs 4 I0/I upon inc emen al addi ions o (a) posi i ely
cha ged MoS2-based ma e ial 3, and (b) neu al MoS2-based ma e ial 2. ............................... 91
Figu e 4.13. (a) Decay p o iles o CDs– 4 upon inc emen al addi ions o posi i ely cha ged
MoS2-based ma e ial 3 o (b) neu al MoS2-based ma e ial 2. ................................................ 92
Figu e 4.14. (a) Linea sweep ol ammog ams o he HER o CDs/MoS2 (black), indi idual
CDs– 4 ( ed) and ba e glassy ca bon elec ode (do ed). Inse : enla ged egion nea he onse .
(b) Ta el plo s o CDs/MoS2 (black) and indi idual CDs– 4 ( ed) showing o e po en ial s
cu en densi y. ......................................................................................................................... 94
Figu e 5.1. H1 NMR spec a o CDs (blue) and -CDs ( ed). ................................................ 103
Figu e 5.2. ATR-IR spec a o as-p oduced CDs (blue) and 1,2-di hiolane modi ied -CDs
( ed). ....................................................................................................................................... 103
xi
Figu e 5.3. UV-Vis (le ) and emission ( igh , λex=370 nm) spec a o as-p oduced CDs (blue)
and 1,2-di hiolane modi ied -CDs ( ed), ob ained in me hanol. ........................................... 104
Figu e 5.4. ATR-IR spec a o o CD-MoS2 (black) and CD-WS2 (g ey). ........................... 106
Figu e 5.5. Raman spec a no malized a A1g mode o (a) ex olia ed MoS2 (blue) and CD-
MoS2 (black) a λexc 633 nm, and (b) ex olia ed WS2 (blue) and CD-WS2 (g ey) a λexc 514 nm.
................................................................................................................................................ 107
Figu e 5.6. Raman spec a (1064 nm) o CDs ( ed), CD-MoS2 (black) and CD-WS2 (g ey).
................................................................................................................................................ 107
Figu e 5.7. The mog aphs o CDs ( ed), ex olia ed MoS2 (do ed black), ex olia ed WS2
(do ed g ay), CD-MoS2 (black), and CD-WS2 (g ey). .......................................................... 108
Figu e 5.8. Rep esen a i e low-magni ica ion HR-STEM-ADF images o CD-MoS2 (le )
and CD-WS2 ( igh ). ............................................................................................................... 109
Figu e 5.9. Rep esen a i e HRSTEM-ADF images o (a, d) CD-MoS2. (b) EDS acqui ed on
he squa ed whi e a ea in (a). In he ed egions o (c) spec a images o SR-EELS we e
eco ded. (d) Ca bon elemen al map ex ac ed om he in eg a ed in ensi y o he C-K edge o
he EELS spec um image eco ded in he ed a ea in (c). (e) Th ee spec a om he sum o
nine (3 × 3) EEL spec a ex ac ed om he ma ked a eas o he EELS SPIM o (c). The C-K
edge (∼284 eV) is obse ed in (ii) and (iii) supe posed wi h he Mo-M edge. The S-L2,3 and
Mo-M edge o MoS2 a e isible in he h ee spec a ((i)−(iii)). ............................................ 110
Figu e 5.10. Rep esen a i e HRSTEM-ADF images o (a, d) CD-WS2. (b) EDS acqui ed on
he squa ed whi e a ea in (a). In he ed egions o (c) spec a images o SR-EELS we e
eco ded. (d) Ca bon elemen al maps ex ac ed om he in eg a ed in ensi y o he C-K edge
o he wo EELS spec a image eco ded in he ed a ea in (c). (e) Th ee spec a om he sum
o 16 (4 × 4) EEL spec a ex ac ed om he EELS SPIM o (c), showing he S-L2,3 and C-K
(in his case only in (ii) and (iii)) edges. The C-K edge (∼284 eV) is obse ed in (ii) and (iii).
The S-L2,3 edge is isible in he h ee spec a ((i)−(iii)). ...................................................... 111
Figu e 5.11. (a) Abso p ion and (b) emission spec a (λex = 370 nm) o CD-MoS2 (black),
CD-WS2 (g ay), and -CDs ( ed), in DMF. ........................................................................... 112
Figu e 5.12. Cyclic ol ammog ams o (a) ex olia ed MoS2, (b) ex olia ed WS2, (c) CD-
MoS2, and (d) CD-WS2 in DMF con aining 0.1 M o n-Bu4NClO4 as elec oly e. Scan a e =
100 mV/s. ............................................................................................................................... 113
Figu e 5.13. Spec al changes obse ed du ing (a) i s oxida ion and (b) i s educ ion o
ex olia ed MoS2, and (c) i s oxida ion and (d) i s educ ion o ex olia ed WS2 in DMF
con aining 0.2 M n-BuN4ClO4 as elec oly e. ........................................................................ 114
xii
Figu e 5.14. Fem osecond ansien abso p ion spec a a he indica ed delay imes o
ex olia ed (a, c) MoS2 and (b, d) WS2, in DMF a he exci a ion wa eleng h o 425 nm (a,b)
and 370 nm (c,d). The igh -hand panel shows in ensi y-wa eleng h maps. ......................... 115
Figu e 5.15. Fem osecond ansien spec a o (a) -CDs, (b) CD-MoS2, and (c) CD-WS2 in
DMF (λexc 370 nm). The igh -hand panel shows in ensi y-wa eleng h maps. ..................... 117
Figu e 5.16. Fem osecond ansien spec a o (a) CD-MoS2, and (b) CD-WS2, in DMF (λexc
425 nm). The igh -hand panels show (ii) in ensi y-wa eleng h map and (iii) an o e lap ime
p o ile o he 688 nm o CD-MoS2 (blue) and ex olia ed MoS2 ( ed) and 652 nm o CD-WS2
(blue) and ex olia ed WS2 ( ed). ............................................................................................ 118
Figu e 5.17. Decay associa ed spec a o (a) ex olia ed MoS2, and (b) CND-MoS2 o he
ansien da a shown in Figu e 5.14a and Figu e 5.16a. ......................................................... 119
Figu e 7.1. Abso p ion (λ 350 nm) s In eg a ed emission plo o di e en concen a ion o
quinine sul a e. ....................................................................................................................... 133
Figu e 9.1. XPS spec a o CDs1 samples ob ained a di e en eac ion imes: CDsA (g een),
CDsB (b own), CDsC (black). The p o ile is he same o all he samples. .......................... 143
Figu e 9.2. Pic u es aken a di e en imes o he CDs 1b syn hesis, wi h he UV lamp o
( op) and on (bo om): a) a e he addi ion o EDC, b) a e 5 minu es, c) a e 20 minu es, d)
a e 30 minu es and addi ion o NaOH solu ion. .................................................................. 172
Figu e 9.3. AFM pic u es o CDs 1a-d. In all he samples, he heigh o he nanopa icles is
comp ised be ween 1-2 nm. ................................................................................................... 173
Figu e 9.4. DOSY spec a o CDs 1a-d. ................................................................................ 174
Figu e 9.5. Visual compa ison be ween he measu ed elemen al composi ion o CDs 1a-d and
he calcula ed elemen al composi ion o he expec ed polyme s uc u e. ............................. 175
Figu e 9.6. IR spec um o CDs 1a. 3400-2800 cm-1: O-H and N-H s e ching, 1704 cm-1:
C=O s e ching (ca boxylic acid), 1650 and 1583 cm-1: C=O s e ching (amide), 1440-1350
cm-1: C-O and C-N s e ching. ............................................................................................... 176
Figu e 9.7. IR spec um o CDs 1b. 3400-2800 cm-1: O-H and N-H s e ching, 1704 cm-1:
C=O s e ching (ca boxylic acid), 1650 and 1567 cm-1: C=O s e ching (amide), 1440-1350
cm-1: C-O and C-N s e ching. ............................................................................................... 176
Figu e 9.8. IR spec um o CDs 1c. 3400-2800 cm-1: O-H and N-H s e ching, 1702 cm-1:
C=O s e ching (ca boxylic acid), 1650 and 1582 cm-1: C=O s e ching (amide), 1440-1350
cm-1: C-O and C-N s e ching. ............................................................................................... 177
xiii
Figu e 9.9. IR spec um o CDs 1d. 3400-2800 cm-1: O-H and N-H s e ching, 1708 cm-1:
C=O s e ching (ca boxylic acid), 1650 and 1588 cm-1: C=O s e ching (amide), 1440-1350
cm-1: C-O and C-N s e ching. ............................................................................................... 177
Figu e 9.10. APT 13C NMR spec um o CDs 1a. Ca boxylic acid and amide C: 182-171
ppm, qua e na y C: 75-72 ppm, me hylene C: 45-36 ppm. The posi i e signal a 21 ppm is due
o DIC impu i ies. ................................................................................................................... 178
Figu e 9.11. 1H NMR spec um o CDs 1a. me hylene H: 3.9-2.3 ppm. The signal a 1.2 ppm
is due o DIC impu i ies. ........................................................................................................ 178
Figu e 9.12. 1H-13C HSQC spec um o CDs 1a. .................................................................. 179
Figu e 9.13. 1H-13C HMBC spec um o CDs 1a. ................................................................. 179
Figu e 9.14. APT 13C NMR spec um o CDs 1b. Ca boxylic acid and amide C: 180-170
ppm, qua e na y C: 75-72 ppm, me hylene C: 46-35 ppm. The signals a 160, 55, 42, 24, 14
ppm a e due o EDC impu i ies. ............................................................................................. 180
Figu e 9.15. 1H NMR spec um o CDs 1b. me hylene H: 3.9-2.3 ppm. The signals a 3.0, 2.8,
1.8, 1.0 ppm a e due o EDC impu i ies. ................................................................................ 180
Figu e 9.16. 1H-13C HSQC spec um o CDs 1b. .................................................................. 181
Figu e 9.17. 1H-13C HMBC spec um o CDs 1b. ................................................................. 181
Figu e 9.18. APT 13C NMR spec um o CDs 1c. Ca boxylic acid and amide C: 180-172
ppm, qua e na y C: 76-72 ppm, me hylene C: 46-35 ppm. The signals a 161, 39, ppm a e due
o DMF aces. ........................................................................................................................ 182
Figu e 9.19. 1H NMR spec um o CDs 1b. me hylene H: 3.8-2.3 ppm. The signals a 2.8
ppm is due o DMF aces. ..................................................................................................... 182
Figu e 9.20. 1H-13C HSQC spec um o CDs 1c. .................................................................. 183
Figu e 9.21. 1H-13C HMBC spec um o CDs 1c. ................................................................. 183
Figu e 9.22. APT 13C NMR spec um o CDs 1d. Ca boxylic acid and amide C: 181-172
ppm, qua e na y C: 75-72 ppm, me hylene C: 46-35 ppm. The signals a 65, 29, 25 ppm a e
due o he THF and i s clea age p oduc by means o HCl. ................................................... 184
Figu e 9.23. 1H NMR spec um o CDs 1d. me hylene H: 3.8-2.3 ppm. The signals a 4.0, 1.7
ppm a e due o he THF and i s clea age p oduc by means o HCl. ..................................... 184
Figu e 9.24. 1H-13C HSQC spec um o CDs 1d. .................................................................. 185
Figu e 9.25. 1H-13C HMBC spec um o CDs 1d. ................................................................. 185
Figu e 9.26. UV/ is spec a o CDs 1a-d. ............................................................................. 186
Figu e 9.27. (le ) exci a ion spec a o di e en emissions and ( igh ) emission spec a o
di e en exci a ions o CDs 1a. .............................................................................................. 186
xx
Lis o Schemes
Scheme 2.1. (Top) Reac ion o EDA wi h CA h ough wo syn he ic pa hways o o m CDs1
and CDs3. (Bo om) Reac ion o EDA wi h TA o o m CDs2. .............................................. 43
Scheme 3.1. Polycondensa ion o CA and EDA h ough ou syn he ic pa hways, o he
ob aining o CDs 1a-d. ............................................................................................................. 69
Scheme 3.2. Syn hesis o CDs 2a- . ......................................................................................... 72
Scheme 3.3. a) polycondensa ion o CA and EDA media ed by coupling agen . b) he addi ion
o a p ima y amine consumes he ac i a ed ca boxylic acids and s ops he polyme iza ion. .. 74
Scheme 4.1. P epa a ion o CDs- 4. ......................................................................................... 82
Scheme 4.2. Func ionaliza ion o MoS2 leading o ammonium modi ied MoS2-based ma e ial
3. ............................................................................................................................................... 83
Scheme 4.3. P epa a ion o he CDs/MoS2 elec os a ic complex. .......................................... 89
Scheme 5.1. syn hesis o CDs and unc ionaliza ion wi h lipoic acid. .................................. 101
Scheme 5.2. Illus a i e p epa a ion o CD-MoS2 and CD-WS2 upon co alen 1,2-di hiolane
unc ionaliza ion o ex olia ed semiconduc ing MoS2 and WS2 nanoshee s. ........................ 105
Scheme 11.1. Syn hesis o aw CDs. ..................................................................................... 241

xxi
Lis o Tables
Table 2.1. Measu ed di usion coe icien (D), calcula ed hyd odynamic adius ( H) and
diame e o CDs1, CDs2, and CDs3. All samples show a diame e be ween 1.2-1.6 nm. ...... 46
Table 2.2. Elemen al analysis o CDs1, CDs2 and CDs3 and he calcula ed pe cen age
(mol%) o he epe i i e uni o he co esponding polyme ic condensa ion p oduc s. .......... 50
Table 2.3. Abso p ion (Eabs) and emission (Eem) ene gies ....................................................... 58
Table 3.1. amines employed o he polycondensa ion, emission maximum, QY and pic u es
(in wa e , UV ligh o and on) o CDs 2a- . ............................................................................ 72
Table 3.2. amine employed o he unc ionaliza ion, emission maximum, QY and pic u es (in
wa e , UV ligh o and on) o CDs 3a-e. ................................................................................. 74
Table 8.1. Measu ed di usion coe icien (D) and he calcula ed hyd odynamic adius ( H)
and diame e o CDs1 samples ob ained a di e en eac ion imes: CDsA, CDsB, CDsC. . 137
Table 8.2. A e age molecula weigh in numbe (Mn ), in weigh (Mw ) and polydispe si y
(Ɖ) o CDs1 samples ob ained a di e en eac ion imes: CDsA, CDsB and CDsC. ........... 138
Table 8.3. Elemen al Analysis o CDs1 samples ob ained a di e en eac ion imes: CDsA,
CDsB, and CDsC. ................................................................................................................... 141
Table 9.1. The measu ed di usion coe icien s (D) and he calcula ed hyd odynamic ays
( H) and diame e s o CDs 1a-d. Assuming a globula shape, he calcula ed size o he
nanopa icles is comp ised be ween 1.2-2.0 nm..................................................................... 174
Table 9.2. C, H, N, O and S mole pe cen ages o CDs 1a-d, ob ained by elemen al analysis.
Addi ionally, he calcula ed elemen al composi ion o he expec ed polyme epe i i e uni is
epo ed o compa ison. ........................................................................................................ 175
Table 9.3. The measu ed di usion coe icien s (D) and he calcula ed hyd odynamic ays
( H) and diame e s o CDs 2a- . Assuming a globula shape, he calcula ed size o he
nanopa icles is comp ised be ween 1.2-2.0 nm, wi h he excep ion o CDs 2c, which show a
size o 4.8 nm. ........................................................................................................................ 191
Table 9.4. C, H, N, O and S mole pe cen ages o CDs 2a, ob ained by elemen al analysis.
Addi ionally, he calcula ed elemen al composi ion o he expec ed polyme epe i i e uni is
epo ed o compa ison. ........................................................................................................ 191
Table 9.5. C, H, N, O and S mole pe cen ages o CDs 2b, ob ained by elemen al analysis.
Addi ionally, he calcula ed elemen al composi ion o he expec ed polyme epe i i e uni is
epo ed o compa ison. ........................................................................................................ 192
xxii
Table 9.6. C, H, N, O and S mole pe cen ages o CDs 2c, ob ained by elemen al analysis.
Addi ionally, he calcula ed elemen al composi ion o he expec ed polyme epe i i e uni is
epo ed o compa ison. ........................................................................................................ 192
Table 9.7. C, H, N, O and S mole pe cen ages o CDs 2d- , ob ained by elemen al analysis.
Addi ionally, he calcula ed elemen al composi ion o he expec ed polyme epe i i e uni is
epo ed o compa ison. ........................................................................................................ 193
Table 9.8. The measu ed di usion coe icien s (D) and he calcula ed hyd odynamic ays
( H) and diame e s o CDs 3a-e. Assuming a globula shape, he calcula ed size o he
nanopa icles is comp ised be ween 1.2-2.4 nm..................................................................... 216
Table 9.9. C, H, N, O and S mole pe cen ages o CDs 3a-e, ob ained by elemen al analysis.
................................................................................................................................................ 216
Table 11.1. C, H, O and N composi ion o ac ion 1-4. ....................................................... 244
xxiii
Lis o abb e ia ions and ac onyms
2D: Two dimensional
AcOE : E hyl Ace a e
AFM: A omic Fo ce Mic oscopy
APT: A ached P o on Tes
BOC: e -Bu oxyca bonyl
CA: Ci ic acid
CDs: Ca bon do s
CEE: C osslink-Enhanced Emission
CV: Cyclic ol amme y
DCM: Dichlo ome hane
DFT: Densi y Func ional Theo y
DIC: N,N′-Diisop opylca bodiimide
DLS: Dynamic ligh sca e ing
DMF: Dime hyl o mamide
DOSY: Di usion o de ed spec oscopy
EDA: E hylenediamine
EDC: N-(3-Dime hylaminop opyl)-N′-e hylca bodiimide hyd ochlo ide
EDS: Ene gy-dispe si e X- ay spec oscopy
EELS: Elec on Ene gy Loss Spec oscopy
FTIR: Fou ie - ans o m in a ed spec oscopy
HB: Hyd ogen Bond
HMBC: He e onuclea Mul iple Bond Co ela ion
HOMO: Highes occupied molecula o bi al
HAADF-STEM: high-angle annula da k- ield scanning ansmission elec on mic oscopy
HRTEM: High esolu ion ansmission elec on mic oscopy
HSQC: he e onuclea Single Quan um Co ela ion
LUMO: Lowes unoccupied molecula o bi al
MeOH: Me hanol
xxi
MWCO: Molecula weigh cu -o
NHS: N-hyd oxysuccinimide
NMR: Nuclea magne ic esonance
PTFE: Poly e a luo oe hylene
QY: Quan um Yield
SEC: Size exclusion ch oma og aphy
TA: T ica ballylic acid
TDDFT: Time Dependen Densi y Func ional Theo y
TEM: T ansmission elec on mic oscopy
TMDs: T ansi ion me al dichalcogenides
THF: Te ahyd o u an
TGA: The mog a ime ic analysis
UV/Vis: Ul a iole / isible spec oscopy
XPS: X- ay pho oelec on spec oscopy
xx
ABSTRACT
Ca bon do s (CDs) a e an eme ging class o o ganic nano-sized pa icles, whose excep ional
pho oluminescence su ely is one o he mos in iguing p ope ies. Thanks o hei pho o-
induced ene gy ans e and cha ge ans e abili y, CDs a e an ex emely aluable ma e ial
o he p epa a ion o pho oca alys s and dono -accep o composi es o ene gy con e sion
applica ions. Mo eo e , he p esence o me al ions as well as o ganic species a ec s hea ily
he CDs’ pho oluminescence in ensi y. Fo his eason, CDs a e widely employed o he
design o highly sensi i e senso s and biosenso s. Finally, CDs demons a ed o be a sa e and
biocompa ible ma e ial, pe ec ly sui able o medical applica ions such as imaging and d ug
deli e y.
Despi e hei consis en use o a ious applica ions, he chemical na u e o CDs and i s
ela ionship wi h hei ou s anding op ical p ope ies is s ill a opic unde deba e, being he
ac ual knowledge incomple e and a imes con adic o y. In ac , he wide a ie y o
p ecu so s and syn he ic me hods employed o he p epa a ion o CDs is e lec ed in he high
a iabili y o hei s uc u es, hampe ing he iden i ica ion o he common undamen al
elemen s behind he luo escence emission. Addi ionally, he lack o unde s anding and
con ol on he syn he ic p ocess unde mines he abili y o design and ailo he CDs s uc u e,
which ins ead is a key poin o imp o ing hei p ope ies o making hem sui able o u he
applica ions.
In his hesis, he i s pa is ocused on undamen al s uc u al and op ical s udies on ci ic
acid-based CDs, which, join ly wi h heo e ical calcula ions, p o ided new insigh s in o he
CDs chemical na u e and u nished a gene al explana ion o hei blue luo escence emission.
Nex , hese indings we e exploi ed o he de elopmen o a no el oom- empe a u e and
e sa ile syn hesis me hod, which allows he a ional design o he CDs polyme s uc u e and
a he same ime hei in-si u unc ionaliza ion, g an ing in his way he ull con ol on he
inal chemical s uc u e. In he las pa o he hesis, he p epa a ion o CDs-based ma e ial
and hei chemical and op ical cha ac e iza ion is epo ed. In he e non-co alen and co alen
app oaches we e bo h employed o combining CDs wi h ansi ion me al dicalchogenides
(TMDs) and c ea ing pho o-ac i e dono -accep o ma e ials o ene gy applica ions.

xx i
Chap e 1 p o ides a gene al o e iew ega ding CDs and CDs based ma e ials. I includes a
ch onological e iew on he undamen al s udies in es iga ing he CDs chemical na u e om
hei disco e y un il he ac ual s a e o he a , as well as a p esen a ion o he pa allel
de elopmen o heo ies abou he o igin o he luo escence. Nex , he mos common
me hods o syn hesis and unc ionaliza ion o CDs a e p esen ed. Finally, oge he wi h many
examples, he employmen o CDs in he ield o sensing, medicine, ca alysis and ene gy
con e sion is desc ibed.
Chap e 2 consis s o an accu a e s uc u al and op ical in es iga ion o polyme ic CDs. In
he e, he choice o he p ecu so s and syn he ic me hods employed was de e minan o
iden i ying he s uc u al ea u es esponsible o he b igh blue luo escence emission. By
sample compa ison, i was p o ed ha he polycondensa ion be ween ci ic acid and
e hylenediamine in o a polyamide is he only necessa y condi ion o ob aining he exci a ion-
independen blue emission. In o de o con i m hese esul s and unde s and he ole o he
o ganic moie ies in ol ed in he luo escence, DFT calcula ions based on he expe imen al
esul s we e pe o med. The compu a ional models showed ha s ong in a-molecula H-
bonds a e esponsible o he high con o ma ional igidi y o CDs, which hampe s ib a ions
and o a ions, p omo ing hus he adia i e elaxa ion. Addi ionally, amide and ca boxylic
acids we e iden i ied espec i ely as HOMO and LUMO o he luo escen p ocess, which
consis s o an in a-molecula cha ge ans e .
Chap e 3 p esen s a no el, e sa ile pa hway owa ds he a ional design o a wide a ie y o
polyme ic luo escen CDs wi h well-de ined s uc u es. The exploi ed eac ion consis s o he
oom- empe a u e ca bodiimide-media ed condensa ion be ween ci ic acid and amines.
Mo eo e , his me hod allows he in-si u in oduc ion o se e al ypes o desi ed moie es on o
he su ace o he CDs, hus achie ing he CDs syn hesis and unc ionaliza ion in only one
s ep.
Chap e 4 ocuses on he p epa a ion, cha ac e iza ion, and s udy o he pho ophysical and
elec oca aly ical p ope ies o CDs/MoS2 elec os a ic complexes. Nega i ely cha ged CDs
p epa ed om mic owa e i adia ion o ci ic acid and e hylenediamine we e employed in he
i a ion essay o a dispe sion o posi i ely cha ged MoS2 oligolaye s. The op ical p ope ies
o he o ming elec os a ic complex we e s udied ongoing. E icien luo escence quenching
o CDs by MoS2 was obse ed and asc ibed o pho oinduced elec on and/o ene gy ans e
as he decay mechanism o he ansduc ion o he single exci ed s a e o CDs. Finally, he
xx ii
elec oca aly ic pe o mance o CDs/MoS2 was assessed owa ds he hyd ogen e olu ion
eac ion and ound supe io as compa ed o ha owed o he indi idual CDs species.
Chap e 5 co e s he p epa a ion o co alen CDs-TMDs (MoS2 and WS2) hyb ids and hei
cha ac e iza ion, including spec oscopic, he mal and elec on mic oscopy imaging me hods.
The p epa a ion o he ma e ial was s a ed by unc ionalizing CDs wi h disul ide moie es.
Thus, he high a ini y o disul ide g oups owa ds Mo and W was exploi ed o a aching
CDs on o he me al a oms de ec s loca ed a he ex olia ed TMDs edges. S eady-s a e and
ime- esol ed luo escence spec oscopy de e mined he occu ence o as ene gy and/o
cha ge ans e p ocesses be ween CDs and TMDs. Fu he mo e, ansien abso p ion
spec oscopy s udies e ealed ha upon MoS2 pho oexci a ion cha ge ans e om an exci on
dissocia ion pa h o MoS2 o CDs, wi hin CD-MoS2, was obse ed. In con as , CD-WS2 did
no display such beha io due o ene ge ic easons. The elec onic p ocesses aking place in
his no el ma e ial ce ainly can be o in e es o he de elopmen o dono -accep o
componen s in iew o ene gy con e sion applica ions.
Finally, Chap e 6 p o ides he gene al conclusion o he indings and an ou look in wha
conce ns possible oppo uni ies and u u e esea ch wo k.
xx iii
RESUMEN
Los Pun os de Ca bono, en inglés Ca bon Do s (CDs), son una clase de pa ículas o gánicas
nanomé icas, cuya excepcional luo escencia es cie amen e una de sus p opiedades más
ascinan es. G acias a p opiedades como la ans e encia de ene gía y/o de ca ga, los CDs
esul an se ma e iales muy a ac i os pa a la p epa ación de o o-ca alizado es y compues os
dono -acep o pa a aplicaciones en el campo de la con e sión de ene gía. Además, la
p esencia de iones me álicos así como de especies o gánicas puede a ec a conside ablemen e
a la in ensidad de la luo escencia de los CDs. Po es a azón, los CDs se u ilizan ampliamen e
pa a el desa ollo de senso es y biosenso es al amen e sensibles. Finalmen e, los CDs son
ma e iales segu os y biocompa ibles, pe ec amen e adecuados pa a aplicaciones médicas
como agen es de con as e o ec o es de á macos.
A pesa de su amplio uso en a ias aplicaciones, la na u aleza química de los CDs y la
elación con sus inc eíbles p opiedades óp icas son oda ía a gumen o de deba e, siendo el
conocimien o ac ual incomple o y a eces con adic o io. Es o se debe ambién a la g an
a iedad de p ecu so es y mé odos de sín esis empleados en la p epa ación de los CDs, lo que
se e leja en la di icul ad de iden i ica los elemen os undamen ales y comunes elacionados
con el p oceso de luo escencia. Además, la al a de comp ensión y de con ol sob e el
p oceso sin é ico limi a la posibilidad de diseña y modi ica la es uc u a de los CDs, lo que
es un ac o cla e pa a mejo a sus p opiedades o adap a las pa a aplicaciones especí icas.
La p ime a pa e de es e abajo de esis se cen a en es udios undamen ales de la es uc u a y
p opiedades óp icas de los CDs de i ados de ácido cí ico y e ilendiamina. Resul ados
expe imen ales de es a in es igación jun o a cálculos eó icos han apo ado nue o
conocimien o con espec o a la na u aleza química de los CDs y ambién han con ibuido a
da una explicación gene al a su emisión de luo escencia azul. Pos e io men e, se han
ap o echado es os descub imien os pa a el desa ollo de un nue o y e sá il mé odo de
sín esis, que consigue el diseño de la es uc u a polimé ica de los CDs y, al mismo iempo, su
uncionalización in-si u, asegu ando de es a mane a un con ol comple o sob e la es uc u a
química inal. En la úl ima pa e de la esis, se epo a la p epa ación de ma e iales basados en
los CDs y su ca ac e ización química y óp ica. Aquí se han u ilizado es a egias de enlace
co alen e y non-co alen e se han u ilizado pa a combina los CDs con dicalcogenu os mono-
capa de me ales de ansición (TMDs: ansi ion me al dichalcogenides) y c ea ma e iales
dono -acep o o oac i os pa a aplicaciones ene gé icas.
xxix
El Capí ulo 1 consis e en un esumen gene al en elación a los CDs y a sus ma e iales
de i ados. Incluye un epaso c onológico de los es udios undamen ales que in es iga on la
na u aleza química de los CDs desde su descub imien o has a el momen o ac ual, así como
una desc ipción del desa ollo pa alelo de eo ías sob e el o igen de la luo escencia.
El Capí ulo 2 p esen a una igu osa in es igación es uc u al y óp ica de los CDs. Aquí, la
elección de los p ecu so es y de los mé odos sin é icos ha sido de e minan e pa a iden i ica
los componen es es uc u ales esponsables de la in ensa emisión de luo escencia azul.
Compa ando los esul ados de las di e en es mues as, se ha es ablecido que la
policondensación en e ácido cí ico y e ilendiamina es la única eacción necesa ia pa a la
ob ención de luo escencia independien e de la exci ación. Pa a con i ma es os esul ados y
pa a en ende el papel de los g upos o ganicos in oluc ados en la luo escencia, se han
ealizado cálculos de DFT ( eo ía uncional de la densidad) basados en los da os
expe imen ales. Los modelos compu acionales enseñan que hay ue es enlaces de hid ogeno
in a-molecula es esponsables de la al a igidez con o macional de los CDs, lo que limi a la
ib ación y o ación de enlaces implicados, omen ando así la elajación adia i a. Además,
amidas y acidos ca boxílicos se han iden i icado espec i amen e como HOMO y LUMO del
p oceso luo escen e, que consis e en una ans e encia de ca ga in a-molecula .
El Capí ulo 3 p esen a un camino nue o y e sá il hacia la sín esis acional de una amplia
a iedad de CDs luo escen es con es uc u as polimé icas bien de inidas. La eacción
u ilizada consis e en la condensación a empe a u a ambien e mediada po ca bodiimida en e
ácido cí ico y e ilenodiamina. Además, es e mé odo posibili a la in oducción in-si u de
dis in os ipos de g upos uncionales en la supe icie de los CDs, log ando así sín esis y
uncionalización en un solo paso.
El Capí ulo 4 se en oca en la p epa ación, ca ac e ización y es udio de las p opiedades
o o ísicas y elec o-ca alí icas de complejos elec oes á icos de CDs/MoS2. CDs ca gados
nega i amen e, p epa ados po i adiación en mic oondas de ácido cí ico y e ilendiamina, se
han empleado en el ensayo de alo ación de una dispe sión de oligo-capas de MoS2 ca gadas
posi i amen e. Asimismo, se han es udiado las p opiedades óp icas del compues o
elec oes á ico du an e la o mación. Se ha obse ado una e icien e desac i ación (quenching)
de la luo escencia de los CDs po pa e del MoS2, lo que se ha a ibuido a un mecanismo de
decaimen o desde el es ado exci ado de single e de los CDs, consis en e en una as e encia de
6
In hese pionee ing wo ks, some common poin s should be highligh ed. The ca bon sou ce
employed he e consis ed o pu e ca bon ma e ials, such as g aphi e, ca bon nano ubes and
ac i e ca bon. The syn he ic p ocedu es in ol ed he des uc ion and oxida ion o he
ma e ial, aiming o c ea e he de ec s ac ing as su ace aps. Addi ionally he luo escence
emission o he as-p oduced nanopa icles commonly showed an exci a ion-dependen
beha io . Conside ing ha hese CDs a e expec ed o ha e la ge sp2 conjuga ed domains
delimi ed by oxygena ed g oups, he exci a ion-dependen PL was a ibu ed o he a ie y o
ap s a es on he pa icles su ace, as well as o he quan um size e ec , i.e. he adia i e
ecombina ion o exci ons whose ene gy depends om he size o he conjuga ed domain.
Wi h hese p emises, passi a ion was conside ed o play a ole in he s abiliza ion o he
ene gy aps, enhancing he emission.
In 2008, he g oup o P. Giannelis e al. epo ed an en i ely di e en app oach o he
syn hesis o pho oluminescen o ganic nanopa icles17-18. Ci a e ammonium sal s and o he
molecula p ecu so s we e hea ed a 300 °C by hyd o he mal ea men o py olysis, ob aining
nanopa icles o <10 nm size and quan um yield (QY) o 3%. Thei op ical p ope ies showed
many simila i ies wi h he ones o he CDs ob ained om agmen a ion and oxida ion o
ca bon ma e ials and an analogy wi h hem was made. Thus, i was sugges ed ha he
ca boniza ion o he molecula p ecu so leads o he o ma ion o a ca bon co e, composed by
co-exis ing a oma ic and alipha ic egions, simila ly o g aphi e oxide. Addi ionally, TEM
images, high wa e solubili y and he p esence o amide bonds p o ed ha a polyme ic co ona
co e s he su ace o he nanopa icles. The e o e, polyme iza ion was p oposed o be he
eac ion s ep p eceding he co e ca boniza ion.
The ollowing s udies explo ed mo e syn he ic ou es, inding ha hyd o he mal ea men 19-
21, py olysis by mic owa e i adia ion22-24 and s ong acid ea men 11 we e all e ec i e one-
s ep me hodologies o he ob aining o luo escen nanopa icles, achie ing be e quan um
yields and a oiding annoying oxida ion and passi a ion s eps wi h espec o he op-down
app oaches. Possibly because hese new ma e ials esembles in size and op ical p ope ies he
i s s luo escen ca bon nanopa icles disco e ed, hey we e as well called ca bon do s (o C-
do s, ca bon nanodo s, ca bon quan um do s e c.), widening and blu ing he limi s o his
de ini ion. This agueness mos likely was encou aged by looking o ans e sal p inciples
beyond he PL, and he a en ion was ini ially ocused on he ca bonized co e and i s
in e ac ion wi h he amo phous su ace, since he syn he ic p ocedu es we e gene ally ha sh
and high empe a u e una oidable o ms sp2 unp edic able s uc u es.

7
The complex luo escence beha io o bo om-up syn he ized CDs is o en desc ibed as a
combina ion o p ocesses, co e ing exci ons ecombina ion (Figu e 1.4a), p esence o ap
s a es which may p omo e he adia i e decay (Figu e 1.4b), and in e ac ion o he oxygena ed
g oups a he edges wi h he conjuga ed domains25. Ne e heless, hese hypo hesis imply (and
he dic iona y sugges s) he exis ence o highly delocalized s a es, i.e. a semi-conduc ing band
om whe e he elec on can decay h ough di e en pa hways. Unde his poin o iew, he
exis ence o a g aphi ized co e, o e ing dlocalized g ound and exci ed s a es, is he necessa y
condi ion o he appea ance o PL, while oxygena ed g oups simply p omo e he adia i e
decay ac ing as localized accep o aps o he exci ed elec ons. Mo eo e in his amewo k
ni ogen is commonly depic ed as a dopan (“N-doped ca bon do s” appea ed mo e han 200
imes in he a icle i les be ween 2010 and 2018; sou ce: Scopus), sugges ing i s pa icipa ion
in he p ocess o elec on delocaliza ion.
Figu e 1.4. (a) PL due o he quan um size e ec . The sum o di e en conjuga ed
domains wi h dis inc ene gy band gaps can be esponsible o he obse ed exci a ion-
dependen PL beha io . (b) Oxygen g oups loca ed a he edges o he conjuga ed
domains can ac as localized ene gy aps, which p omo e he adia i e elaxa ion.
8
Howe e , in 2012 P. Giannelis e al. s udied he o ma ion o CDs by py olysis o ci ic acid
and e hanolamine a di e en empe a u es and obse ed ha ca boniza ion only s a s abo e
200 °C.26 In e es ingly, CDs p epa ed a lowe empe a u es display e y in ense PL emission
independen om he exci a ion (QY=50%). Inc easing he empe a u e, his ea u es
d as ically all, almos disappea ing a 300 °C, while wi h he g ow h o he ca bonized co e a
new ype o exci a ion-dependen PL is obse ed, bu wi h conside ably lowe quan um yield
(4% a 300 °C). Thus, i was p oposed ha a ela i ely low empe a u e (<200 °C) he
o ma ion o molecula luo opho es occu s. Inc easing he empe a u e he luo opho e is
consumed by he ca boniza ion p ocess, and he exci a ion-dependen PL ises a he expenses
o he exci a ion-independen componen . Fu he s udies b ough addi ional a gumen s o
he exis ence o he molecula luo opho es27-29.
The s uc u al ecogni ion o he molecula luo opho e is la gely pu sued and since 2015
se e al epo s linked he PL o pa icula a oma ic s uc u es, o med when ci ic acid and
amines p ecu so s we e employed. The i s epo in his di ec ion, by B. Yang e al.,
ecognized he o igin o he molecula s a e luo escence in he IPCA conjuga ed molecule
(imidazo[1,2-a]py idine-7-ca boxylic acid), which was ound a ached o he ca bon co e and
whose op ical p ope ies a e in good ag eemen wi h he CDs exci a ion-independen blue PL
(Figu e 1.5a,b).30-31 Na u ally, he luo opho e s uc u e depends on he eagen s employed
(Figu e 1.5c,d). Many publica ions iden i ied simila py idine-like/ca boxylic acid s uc u es
as o igin o he molecula s a e PL32-36, also unde lining he in luence o sup amolecula H-
bond o agg ega ion.
9
Figu e 1.5. eac ions ha occu du ing he hyd o he mal ea men o ci ic acid and
e hylenediamine owa ds he o ma ion o molecula luo opho es, polyme clus e s and
he ca bonized co e ( om e . 30) (b) IPCA luo opho e and i s op ical p ope ies ( om
e . 30). (c) molecula luo opho e and co e con ibu ions o he abso p ion o CDs ( om
e 36). (d) he hyd o he mal ea men o ci ic acid wi h di e en amines p oduces
molecula luo opho es ( om e . 32).
Ne e heless, in he las ew yea s ano he ele an ype o PL p ocess was discussed in
ela ion o he CDs op ical beha io . I was es ablished ha non-conjuga ed polyme s a e
capable o displaying b igh PL emission in condi ion o high igidi y. Agg ega ion37-38,
hype b anching39-40, sel -assembly41 o c osslinking40, 42 a e some o he condi ions ha
enable he PL emission in non-conjuga ed polyme s (Figu e 1.6). This phenomenon was
he e o e called c osslink enhanced emission (CEE) e ec . B. Yang documen ed s ong PL
emission in a ious CDs sys ems p epa ed in mild condi ions, ega dless he absence o
ca bon co e o simple C=C double bonds and hus excluding also he p esence o a oma ic
molecula luo opho es2, 43-46. The PL o CDs was he e o e ela ed o he immobiliza ion o
he so-called sub- luo opho es loca ed on he polyme s uc u e, which a e o ganic
ch omopho es (such as C=O, C=N, N=O, co esponding o example o amide and ca boxylic
acid g oups) ha , due o he c osslinked and igid s uc u e o he CDs, become able o e-
emi he abso bed pho ons by means o adia i e pa hways.
10
Figu e 1.6. (a) some examples o in e ac ions esponsible o he CEE e ec ( om e .
43). (b) a luo escen c osslinked copolyme om polye hyleneimine and polylac ic acid
( om e . 40).
The emission due o he CEE e ec may be a ec ed o no om he exci a ion wa eleng h
employed (Figu e 1.7). When he ene gy dis ibu ion o he polyme con o ma ions
o igina ing he PL is na ow, i.e. he PL cen e s a e simila , he emission is independen om
he exci a ion. On he o he hand, when he emi ing s a es a e o igina ed om di e en
con o ma ions, emission can be uned by exci a ion. In ac , he lowe ing o he exci a ion
ene gy lea es he a ious highe emission ene gy le els inaccessible and he exclusion o
hei con ibu ion om he o al PL is no only e lec ed in he in ensi y dec ease, bu also he
emission ed-shi 47. The a e o agg ega ion can also b oaden he ene gy le els and make PL
dependen om exci a ion37.
11
Figu e 1.7. (a) exci a ion dependen PL om non-conjuga ed c osslinked PEI
nanopa icles ( om e . 44), (b) exci a ion independen PL om non-conjuga ed
polyamide nanopa icles ( om e . 48).
1.2.3. Discussion
F om he CDs disco e y up o now, ou coexis ing in e p e a ions o he PL phenomena we e
o mula ed in he ollowing ch onological o de :
1. Quan um size e ec o a oma ic domains wi h di e en sizes (exci a ion dependen ).
2. T ap s a es om oxygen moie ies and om passi a ion by ni ogen con aining
molecules (exci a ion dependen o independen , acco ding o he ene gy dis ibu ion
o he aps).
3. Conjuga ed molecula luo opho es a ached on he CDs su ace (exci a ion
independen ).
4. CEE e ec o non-conjuga ed polyme (exci a ion dependen o independen ,
acco ding o he dis ibu ion o con o ma ions and agg ega ion e ec s).
Na u ally, he lis ed PL emi e s a e no mu ually exclusi e. On he con a y, he complex
op ical beha io o he CDs has been equen ly desc ibed as he sum o di e en
con ibu ions. Ne e heless, he ga he ed in o ma ion can be exploi ed o discuss in hindsigh
he way ha s a emen s abou he luo escence-s uc u e ela ionship should be a gued om
he expe imen al da a. A e ision o he mos widesp ead in e p e a ions in a ou o an
upda ed poin o iew ha conside s and includes he la es indings is highly desi able o
p o iding be e basis o he u u e de elopmen o he ield o CDs.
As a o emen ioned, he PL due o quan um size e ec , ap s a es and passi a ion implies he
p esence o la ge conjuga ed domains in he CDs s uc u e. When CDs we e disco e ed, he
employed me hods gene ally in ol ed he use o pu e ca bon ma e ial as p ecu so , as well as
e y high empe a u es and ha sh ea men s. Thus, i is easonable ha he obse ed PL in

12
hese nanopa icles has o be somehow ela ed o hei conjuga ed s uc u es. Nowadays hese
ma e ials a e mos likely classi ied as GQDs, a class o ca bon nanopa icles consis ing o
nano-sized single o mul ilaye o g aphene oxide. The bo om-up app oaches howe e a o d
comple ely di e en esul s: he use o o ganic molecules as p ecu so s equi es di e se
p ocedu es, which gene ally in ol e wo consequen ial syn he ic s eps: he o ma ion o he
polyme nanopa icles and hei pa ial ca boniza ion. Possibly due o he ac ha he bo om-
up app oach ollowed ch onologically he op-down app oach, ca boniza ion has been
conside ed o long ime he key s ep o enabling he PL p ope ies o CDs and i has been
pu sued by employing ha sh p ocedu es, wi h empe a u es no lowe han 150-250 °C. High
empe a u es p omo e dehyd a ion and deca boxyla ion, which a e eac ions equi ed o he
o ma ion o a oma ic s uc u es. As p e iously epo ed, hese s uc u es may in ol e
indi idual conjuga ed molecula luo opho es, whose PL is independen om he exci a ion,
o , a highe empe a u e, andom g aphi ic domains. PL dependency om he exci a ion has
been gene ally ela ed o hese las p oduc s o ca boniza ion. Howe e exci a ion dependency
should no be conside ed a p oo o he con ibu ion o g aphi ic domains o he PL, since
compa able exci a ion-dependen emission was also epo ed o pu e non-conjuga ed
polyme nanopa icles. On he con a y, since polyme iza ion is he p elimina y s ep o he
ca boniza ion (Figu e 1.8a), he hypo hesis ha PL emission is due o he CEE e ec should
be conside ed i s , assuming ha he syn he ic me hod does no achie e he comple e
ca boniza ion (>300 °C) (Figu e 1.8b).
Figu e 1.8. (a) polyme iza ion and ca boniza ion s ep o ci ic acid-based CDs. (b)
Schema ic ep esen a ion o he emission cha ac e is ics o h ee pho oac i e species
p oduced om he he mal ea men o mix u e o ci ic acid and e hanolamine.
Du ing py olysis, he o ganic luo opho es (blue g oups) a e consumed o he buildup
o he ca bonized co e (black sphe e) so ha he PL componen ha co esponds o he
ca bonized co e (black ba s) inc eases a he expenses o he componen ha a ises om
he o ganic luo opho es (blue ba s) ( om e . 26).
13
Addi ionally, e en he simple p esence o g aphi ized domains should be p o ed ca e ully. I
was epo ed ha also polyme s can o m c ys alline s uc u e inside he CDs, which could be
po en ially mis aken as g aphi e la ice when analyzed by TEM and XRD (Figu e 1.9).48
These echniques a e employed ou inely o demons a ing he CDs g aphi ic na u e, join ly
wi h XPS analysis. Howe e XPS s uc u al a ibu ion is a ely suppo ed by o he
echniques o he p ecise de e mina ion o he ca bon s uc u es and he e o e i has a
somewha a bi a y as e. Fo an imp o ed s uc u al cha ac e iza ion, NMR spec oscopy can
o e a wide choice o expe imen s ha allow he ecogni ion o he CDs ea u es, easily
e ealing he a e and he ype o ca bonized s uc u es, as well as imp o ing he
unde s anding o he polyme componen . Finally, he passi a ion p ocess should be discussed
unde he ligh o he CEE e ec . Passi a ion wi h amine-con aining molecules o polyme s
has been la gely exploi ed o o igina ing o enhancing he PL o ca bon nanopa icles
ca ying ca boxylic acids. This p ocess, p omo ed by hea ing, has been equen ly ela ed o
he s abiliza ion o he ap s a es, as well as o he doping o he conjuga ed s uc u es.
Ne e heless, amide is known o inc ease he molecule s uc u al igidi y, possibly p omo ing
he CEE e ec , and could also pa icipa e o he PL emission as sub luo opho e. A ole o
ni ogen a oms, independen om he p esence o conjuga ed sys ems, should be ce ainly
conside ed when amines and ca boxylic acids a e ound among he CDs p ecu so s.
Figu e 1.9. (le ) TEM image and ( igh ) plausible agg ega ion pa e n o polyme CDs,
esembling g aphi e la ice ( om e . 48).
1.2.4. Conclusion
In summa y, a b ie ch onological epo was in ended o d aw he a en ion o he eade on
he in e connec ion be ween bi h and e olu ion o he CDs syn hesis app oaches and he
de elopmen o heo ies ega ding he s uc u e/PL ela ionship. Unde he ligh o he la es
14
indings, he alidi y limi s o some es ablished in e p e a ions conce ning he PL chemical
na u e o CDs we e econside ed, poin ing he a en ion on he unde es ima ed ole o he
polyme componen , which, in con as o he ca bonized co e, is always p esen when
molecula p ecu so a e employed in he syn hesis. In pa icula , i is shown ha ac s such as
PL dependence om he exci a ion and p esence o C=C double bonds canno be p esen ed as
he sole e idences o a con ibu ion om he ca bonized componen o he PL, when he
p esence o he polyme componen could u nish alone a sel -su icien explana ion. Fo
equi alen easons i is p oposed o conside ni ogen no only o i s possible elec onic
pa icipa ion on he conjuga ed s uc u es, bu also and p ima ily as amide, when ca boxylic
acids and amines a e employed in he CDs syn hesis. Amide in ac could play a ole in he
PL p ocess independen ly om he exis ence o a ca bonized co e. Finally, a wide use o he
NMR spec oscopy is encou aged o sa ely asce aining he p esence and he ex en o he
ca bonized componen , as well as he na u e o he polyme s uc u e.
1.3. P ecu so s and syn hesis me hods o CDs
1.3.1. In oduc ion
In his chap e a desc ip ion o he p ecu so s and he syn he ic me hods employed o he
syn hesis o CDs is p esen ed. In ac , hese wo poin s a e undamen al o unde s anding
hei chemical and op ical p ope ies and hey also will u nish an idea o he ex eme a ie y
o s uc u es and ma e ials ha goes by he name o CDs.
1.3.2. P ecu so s
Fluo escen nanopa icles ha e been p oduced om many and e y di e en p ecu so s.
Indeed, any oxygen- and ni ogen-con aining o ganic molecule can be employed, wi hou
nei he he need o complex syn he ic p ocesses no di icul pu i icia ion s eps (basically, he
majo i y o hese p ocedu es in ol es he simple hea ing o he s a ing ma e ial in solu ion,
as desc ibed in he ollowing sec ions). Fo his eason, esea che s we e e y imagina i e a
he momen o he p ecu so s choice. Fo example na u al subs ances we e ex ensi ely
explo ed as sou ce o he ob aining o CDs and included g ass49, hai ibe s50, o ange juice51,
melon peel52, ice lou 53, papaya54 and u ine55 (pee-do s). Ne e heless, mo e o dina y
eagen s a e usually p e e ed. Ac ually, CDs a e no mally ob ained om simple molecules
ich in oxygen g oups, ypically suga s, aminoacids, asco bic acid and ci ic acid. P obably,
ci ic acid is he mos common eagen ; so much ha ci a e-based CDs ecen ly dese ed
15
alone a ull e iew.56 I is widely accep ed ha he p esence o ni ogen is esponsible o a
s ong enhancemen o he luo escence emission and he e o e ni ogen-con aining molecules
a e also no mally ound among he p ecu so s. In pa icula ammonia32, u ea57,
e hylenediamine45 and o he simple amines a e o en employed. Also L-lysine has been used
o his pu pose58-60, while L-cys eine is added when he in oduc ion o sul u is desi ed.61-62
Finally, polyme s cons i u e ano he exploi ed ca ego y o p ecu so , among which
polysaccha ides (such as chi osan)63, polye hylene glycol64, polyacids45 and polyamines44. In
gene al, he use o molecula p ecu so s is mo e widesp ead wi h espec o na u al ma e ials
and polyme s, p obably because i allows he ob aining o simple s uc u es wi h be e
de ined p ope ies.
1.3.3. Syn he ic me hods
Due o he inc easing abili y o unde s and he ela ionship be ween s uc u e and luo escence
o CDs, some olde syn he ic p ocedu es (such as lase abla ion/oxida ion ou e, combus ion,
addi ional passi a ion s eps) we e eplaced along he yea s wi h mo e e icien app oaches
(see Chap e 1.2 o de ails). In gene al, he majo i y o he employed me hodologies in ol e
ha sh empe a u e condi ions, in o de o achie e he condensa ion and dehyd a ion eac ions
esponsible o he g ow h o he CDs. In his sec ion he mos nowadays common p ocedu es
o he ob aining o CDs, i.e. hyd o he mal ea men , mic owa e i adia ion, o he
ca boniza ion p ocedu es and polyme iza ion, a e desc ibed and illus a ed wi h ew
examples.
1.3.3.1 Hyd o he mal ea men
The hyd o he mal me hod is based on he employmen o au ocla e (Figu e 1.10) o ea ing
a high empe a u e and high p essu e he wa e solu ion con aining he p ecu so s. Typically
he epo ed syn hesis empe a u es o CDs a e ound be ween 150-250 °C and he ime o
eac ion is usually comp ised be ween 1-6 hou s. This me hod is p obably he mos
widesp ead, because i allows o ob ain nanopa icles wi h con ollable size, su ace
modi ica ions and high s abili y.32, 51, 60-62, 64-70 B. Yang e al. exploi ed he hyd o he mal
me hod o syn he izing a wide a ie y o CDs om ci ic acid and di e en amines.27
Mo eo e hey pe o med he syn hesis a di e en empe a u es, om 150 o 250 °C,
obse ing a end in he quan um yield, which laid he basis o he unde s anding o he
polyme s uc u e ole in he luo escence beha io .
22
1.5. Toxici y o CDs
Since hei disco e y, CDs ha e been immedia ely ecognized as an in e es ing al e na i e o
semiconduc o quan um do s (QDs) in biological and medical applica ions. In ac , while he
employmen o QDs is limi ed by he in insic oxici y associa ed o hei me allic
composi ion, CDs a e made o biocompa ible elemen s and he e o e o e a sa e choice.
Se e al s udies we e pe o med in o de o assess he oxici y o a ious CDs in i o and in
i o. Y. Zhang e al. moni o ed he g ow h o g een beans in a CDs solu ion, in a CdTe QDs
solu ion and in wa e .94 While he bean sp ou s esul ed pa hological in he QDs solu ion, hei
g ow h was compa able in he CDs solu ion and in wa e . The luo escence p ope ies o he
bean plan p o ed ha CDs a e able o pe mea e h oughou he plan cells wi h good
biocompa ibili y and ha hey a e non- oxic and do no hinde plan g ow h. In he wo k o D.
Cui e al. he acu e oxici y, subacu e oxici y and geno oxici y o CDs was sys ema ically
es ed, concluding ha no signi ican oxici y e ec s we e de ec ed in mice o gans.95 O he
s udies epo ed he employmen o CDs o in i o and in i o imaging o a ious umo cell
lines, wi hou inding any signi ican oxici y.96 Also o he cell ypes we e in es iga ed. S. K.
Kailasa used CDs as p obes o imaging o bac e ial and ungal cells.97 In bo h cases he
in e naliza ion occu ed success ully wi hou any oxic e ec on he cells. CDs also p o ed o
be able o dec ease he oxici y o o he d ug ec o s. Polye hyleneimine (PEI) is an e icien
ec o o gene deli e y, bu i s use is associa ed wi h cy o oxici y. In he wo k o W. Liu e
al., PEI-passi a ed CDs showed a DNA ans ec ion e iciency in i o compa able o PEI
alone, bu wi h dec eased cy o oxici y.98 Finally, a deep s udy on he pha macokine ic o
PEG- unc ionalized CDs was pe o med by he g oup o X. Chen.99 The e ec s o
in a enous, in amuscula and subcu aneous ou es we e compa ed, obse ing ha in he
h ee cases CDs a e apidly concen a ed in kidneys and li e and e icien ly exc e ed om
he body, wi hou showing app eciable oxici y.
In conclusion, e en i CDs chemical s uc u e and p ope ies can be di e en om one
ano he due o he di e en p ecu so s and me hods employed o hei syn hesis, a huge
amoun o oxici y s udies in i o and in i o on nume ous ypes o cells and in mice
indica es ha hese nanopa icles a e gene ally sa e and biocompa ible. Also o his eason
he impac o CDs on he p epa a ion o nano echnologies and ma e ials o bioimaging,
biosensing, d ug deli e y and o he medical applica ions is po en ially high and hus his ield
is apidly de eloping.

23
1.6. Func ionaliza ion o CDs o biomedical applica ions
1.6.1. In oduc ion
Many in e es ing applica ions a e pe ec ly sui ed o he employmen o CDs, including
me al sensing, biomolecule sensing, bioimaging and d ug deli e y. Indeed b igh
pho oluminescence and high wa e solubili y and biocompa ibili y makes CDs e y p omising
candida es o analy ical and medical pu poses. Howe e , in iew o hei use a c i ical
equi emen is ha he nanopa icles mus be selec i e, ha is o say ha CDs should display a
s ongly p e e en ial in e ac ion wi h he a ge o each/analyze. Ac ually, he me hod and he
p ecu so s equen ly employed o he syn hesis o CDs do no con e hem he desi ed
selec i i y, and he p is ine ma e ial lacks o o ganic g oups o he speci ic ecogni ion o
me als o biological sys ems. Fo his eason u he modi ica ion s a egies ha e had an
impo an ole o he de eloping o no el CDs-based ma e ials and a la ge numbe o s udies
in he las wo- h ee yea s epo ed he use o unc ionalized CDs o sensing and bioimaging.
A widesp ead s a egy is based on he CDs co alen unc ionaliza ion, which exploi s he
chemical eac i i y o he o ganic g oups on he CDs su ace in o de o o m he chemical
bond wi h he moie ies in ended o he molecula ecogni ion. Mo eo e his app oach can
ailo o enhance he pho oluminescence ea u es o he nanopa icles.
1.6.2. Func ionaliza ion h ough amide bond
Among all he ypes o co alen unc ionaliza ion epo ed in li e a u e, he amide bond
o ma ion is wi hou any doub he mos common. In ac he p ecu so s employed o he
CDs syn hesis equen ly ca y ca boxylic acids, amines o hey a e ea ed in oxidizing
condi ions. The e o e a e y simple s a egy such as he EDC/NHS (N-(3-
Dime hylaminop opyl)-N′-e hylca bodiimide hyd ochlo ide/N-hyd oxysuccinimide )
ac i a ion o ca boxylic acids p o ide a use ul pa h o he amide bond o ma ion (Figu e
1.18).
24
Figu e 1.17. mechanism o he amide bond o ma ion ca alyzed by EDC/NHS.
Ca boxylic acid eac s wi h 1-E hyl-3-(3-
dime hylaminop opyl)ca bodiimide hyd ochlo ide (EDC), o ming an uns able
in e media e (1). The addi ion o N-Hyd oxysuccinimide (NHS) cause he clea age o he
EDC bond and a less labile NHS es e is o med (2). Finally an amine is added (3) and
he amide bond is achie ed.
Fu he mo e, some s udies epo ed an enhancemen o he luo escence emission a e he
o ma ion o he amides, hus e ealing an addi ional ad an age o his co alen app oach. Fo
example Dong e al. ac i a ed by EDC/NHS coupling he ca boxylic acids o CDs ob ained
om hyd o he mal ea men o glucose and unc ionalized hem wi h e hylenediamine.100
The amide bond o ma ion imp o ed he QY om 1.3 o 3.0%. CDs sensi i i y owa ds
ce ain me al ions is o en high due o he acili y wi h which hose can quench he
luo escence, bu selec i i y mus be imp o ed. Fo example polyamine molecules such as
ie hylene e amine (TETA) a e good chelan s o coppe ions. The e o e he g oup o Yang
used he EDC/NHS p o ocol o a aching TETA on he ca boxylic acids o CDs made om
ci ic acid and u ea.101 The as-p oduced ma e ial was used o he de ec ion o Cu2+ and GSH
(glu a hione). In ac , Cu2+ could bind he CDs su ace and quench he PL emission. Fu he
addi ion o GSH can eco e i , due o he s onge abili y o GSH o bind he coppe ions. In
his way GSH concen a ions o 0.2-175 µM we e de ec ed and he modi ied CDs we e also
applied in li ing yeas cells o de ec ing Cu2+ and GSH. Simila expe imen s we e pe o med
by Chen e al., who p epa ed CDs om ci ic acid and e hylenediamine hyd o he mal
ea men and coupled hem wi h 1,4,8,11 e aazacyclo e adecane cyclam h ough he EDC
chemis y.80 Cyclam ing was exploi ed o hos ing coppe ions and he CDs luo escence was
comple ely quenched (Figu e 1.19). This ma e ial was used in HeLa cells o moni o ing he
concen a ion o S2- ions, which a e able o emo e he coppe om cyclam and eco e he
luo escence. In his way a concen a ion ange o 0-15 µM o S2- could be de ec ed.
25
Figu e 1.18. luo escence quenching and eco e y o cyclam- unc ionalized CDs,
espec i ely by Cu2+ and S2- ions ( ials pic u es om e . 80).
An example o CDs-based biosenso is he ma e ial p epa ed by Chai e al., who conjuga ed
CDs ca ying –COOH moie ies wi h dopamine h ough ca alyzed amide bond o ma ion.102
This ma e ial was used o de ec he concen a ion/ac i i y o y osinase, an enzyme ha
ca alyzes he oxida ion o he dopamine di-hyd oxy phenyl ing o he co esponding
quinone.103 The dopapine quinone is able o quench he CDs luo escence as a esul o an
in amolecula pho o-induced cha ge ans e and, he e o e, he dec ease in luo escence
emission is p opo ional o he y osinase ac i i y. Zhong e al. a ached ins ead he
glycopep ide an ibio ic Vancomycin on CDs made om ci ic acid and u ea, also in his case
exploi ing he p esence o ca boxylic g oups o he conjuga ion.104 Vancomycin is able o
selec i ely a ge he bac e ia S aphylococcus au eus, because i s e minal pep ide sequence
D-Ala-D-Ala binds speci ically he g am-posi i e bac e ia cell walls. Once ancomycin was
co alen ly linked o he CDs, a quenching was measu ed because o he bac e ia p esence,
which concen a ion could be he e o e quan i a i ely de e mined in he ange o 3.18 × 105 –
1.59 × 108 c u mL-1. Simila ly, he g oup o Wang de eloped a luo ome ic essay o he
g am-nega i e bac e ia Salmonella yphimu ium.105 The senso was p epa ed by coupling o
he CDs a speci ic ap ame , able o ecognize he bac e ia’s ou e memb ane p o eins. The
con ac o he unc ionalized CDs wi h he bac e ia induced a measu able loss o PL emission,
co esponding o he bac e ia concen a ion. CDs-based senso s o small biomolecules we e
also p epa ed eso ing o he amide unc ionaliza ion. Cyclodex in has a ing-like molecula
s uc u e, whe e he in e nal pa is hyd ophobic while he ex e nal hyd ophilic, hus
p omo ing he hos -gues in e ac ion wi h hyd ophobic molecules such as p-ni ophenol,
26
which is a quenche o he CDs emission. The e o e Sun e al. unc ionalized he CDs wi h 6-
aminoe hylamino-β-cyclodex in ia EDC/NHS coupling and illed i wi h p-ni ophenol.106
The as-p epa ed ma e ial showed excellen sensing p ope ies owa ds choles e ol, which can
eplace p-ni ophenol as he cyclodex in gues molecule, causing a p opo ional enhancemen
o he CDs luo escence (Figu e 1.20).
Figu e 1.19. sensing mechanism based on he hos -gues in e ac ion o p-ni ophenol and
choles e ol wi h β-cyclodex in- unc ionalized CDs ( om e . 106).
An equi alen sensing s a egy was exploi ed by Luo e al., ha syn he ized CDs om ci ic
acid and cys eine and conjuga ed hem wi h cyclodex in. Fe ocenylme hyl
ime hylammonium iodide was used as a gues molecule in o de o quench comple ely he
CDs emission. This sys em was hen success ully employed o he de ec ion o es os e one,
which, being less pola hen he e ocene compound, o ms be e hos -gues in e ac ion wi h
cyclodex in and could quan i a i ely eco e he luo escence emission.
1.6.3. O he co alen unc ionaliza ions
Al e na i e me hods o he amide bond o ma ion o he CDs co alen unc ionaliza ion
in ol e es e i ica ion o sul onyla ion. Fo example, Alga a e al. used me cap osuccinic acid
o unc ionalizing CDs made om lac ose, exploi ing he e o e he alcohol moie ies o he
u he es e i ica ion (Figu e 1.21).107 The unc ionalized CDs could selec i ely sense Ag+
concen a ions o 0-30 µM in wa e , hanks o he abili y o he hiol g oup o o m a complex
wi h sil e , which is esponsible o he s a ic quenching o he CDs.
27
Figu e 1.20. Me cap osuccinic acid in acid condi ions is used o he CDs
unc ionaliza ion. The as-p oduced nanopa icles a e selec i ely quenched by Ag+ ions
( e . 107).
Amino-con aining CDs can be modi ied by sul onyla ion, i. e. using sul onyl chlo ide
compounds o he o ma ion o he sul onamide. In his way, Wang e al. a ached 2,4-
dini obenzene, a speci ic ligand o selenocys eine, o he nanopa icles, esul ing in he
comple e quenching o hei luo escence.108 Selenocys eine was able o es o e he
luo escence, clea ing by nucleophilic subs i u ion he 2,4-dini obenzene unc ionali ies,
while cys eine, homocys eine, glu a hione and o he s aminoacids didn’ show almos any
e ec on he CDs emission (Figu e 1.22). The e o e he as-p epa ed senso showed o be
capable o selec i ely imaging selenol in li ing cells in a linea ange o 0.2-30 µM.
Figu e 1.21. a) sul onamide bond o ma ion and clea age on CDs om e . 108 and
luo escence dependence. b) selec i i y owa ds selenocys eine (Sec).

28
1.7. CDs in pho oca alysis and sola cells
1.7.1. in oduc ion
PL phenomena in CDs a e he mos e iden sign o in e es ing unde lying p ope ies,
including cha ge sepa a ion and dono -accep o beha io , pho oca aly ic ac i i y and pho on
ha es ing abili y. The ea ly and apid disco e y o all hese p ope ies immedia ely d ew he
a en ion om he ene gy con e sion ield. Nowadays esea che s a e widely employing CDs
o he p epa a ion o pho oca alys s and sola cells laye componen s, disclosing s ep by s ep
hei po en iali y and e ealing he ex eme e sa ili y and easiness o p ocessing ha a e
peculia o his ma e ial. In his chap e a desc ip ion o he CDs ole in ene gy applica ion is
gi en, join ly wi h ew examples.
1.7.2. Pho oca alysis
Thanks o hei special op ical beha io , as well as o he high wa e solubili y, excellen
en i onmen al compa ibili y and easiness o p oduc ion, CDs ha e been exploi ed o he
p epa a ion o se e al e icien pho oca alys s, in ac CDs accep o abili y s abilizes he
pho o-induced cha ge sepa a ion occu ing on o he ma e ials, displacing he elec ons and
he e o e delaying he elec on-hole ecombina ion. In he wo k o S.-Y. Kwak e al. CDs
p epa ed om hyd o he mal ea men o asco bic acid we e embedded wi h mesopo ous
hema i e clus e s and he pho oca aly ic deg ada ion o me hylene blue was s udied.109 The
ema kably highe deg ada ion e iciency o he composi e wi h espec o he hema i e alone
highligh ed he ole o CDs, which we e able o ans e he elec on om hema i e o he
oxygen specie ha s a s he me hylene blue deg ada ion mechanism. A simila beha io is
obse ed in he CDs/CdS he e ojunc ion p epa ed by H.-L. Zhang e al., which showed
imp o ed pho oca aly ic abili y owa ds p-ni obenzene educ ion. In he e, he CDs we e
p epa ed by hea ing L-cys eine a 280 °C o 5 minu es and mixed wi h CdS quan um do s ia
an elec opho e ic and sequen ial chemical ba h deposi ion me hod, achie ing he o ma ion
o he he e ojunc ion.110 Upon isible ligh i adia ion, elec on-hole sepa a ion occu s on CdS
and elec ons a e accep ed by CDs, which e icien ly ca alyze he p-ni obenzene educ ion
(Figu e 1.23).
29
Figu e 1.22. illus a ion o he CDs/CdS he e ojunc ion and i s pho oca aly ic ac i i y
owa ds p-ni obenzene ( om e . 110).
One las example o he e sa ili y o CDs in pho oca alysis, he wo k o R. Chen e al. epo s
he e alua ion o he pho oca aly ic ac i i y o he monolaye ed 2D ma e ial BiMoO6 mixed
in solu ion wi h CDs syn he ized om hyd o he mal ea men o ci ic acid and
e hylenediamine.111 The e icien deg ada ion unde isible ligh o ou pollu an s, i.e.
cip o loxacin, bisphenol A, e acycline hyd ochlo ide, and me hylene blue was achie ed,
p omo ed by he elec on accep o ole o CDs.
1.7.3. Sola cells
CDs ha e been ex ensi ely employed in sola cell o co e ing mul iple oles, including as
elec ode componen s, mixed in he anspo laye o ac ing as pho osensi ize and spec um
con e e . H.-S. Choi syn he ized CDs by mic owa e i adia ion o ci ic acid and u ea.112
The CDs we e used as ini ia o s o he dend i ic g ow h o Au, ob aining in his way he
ma e ial u he employed as coun e elec ode o he ZnO nanowi e/CdS/CdSe quan um do -
sensi ized sola cell. The as-p epa ed coun e -elec ode showed be e pe o mance wi h
espec o commonly used Au-spu e ed coun e elec odes, inc easing he powe con e sion
e iciency om 3.6% o 5.4%. The highe pe o mance o he CDs/Au coun e elec ode was
asc ibed o i s much la ge su ace a ea han he Au-spu e ed coun e elec ode, and he e o e
o an inc ease in he numbe o elec oca aly ic ac i e si es. The g oup o E. Paloma es ins ead
employed he CDs in he p epa a ion o he hole- anspo laye o pe o ski e sola cells.113
CDs we e syn he ized by hyd o he mal ea men o ci ic acid and p-phenylenediamine. Nex
hey we e included in he sola cell ab ica ion p ocess as hole- anspo ma e ial on op o he
pe o ski e laye . In ac , he measu ed HOMO and LUMO ene gies o CDs we e ound o be
adequa e on one side o ensu ing he hole ans e and blocking he elec on ans e on he
30
o he . The as-p epa ed de ice showed a powe con e sion e iciency o 3%, p o ing he
capabili y o CDs as hole- anspo e ma e ial. In he s udy o M. Q. Zhang e al. CDs we e
used o inc easing he ha es ing e iciency o he sola cell, widening i s abso p ion
spec um (Figu e 1.24).114 In ac , he abso p ion o CDs p epa ed om he hyd o he mal
ea men o asco bic acid and silane is ound in he UV ange, while hei luo escence
emission is blue. Blue ligh ma ches wi h he esponse cu e o he ac i e laye , consis ing o
poly(3-hexyl hiophene): [6,6]-phenyl-C61-bu y ic acid me hyl es e (P3HT:PCBM), while
UV ligh does no . The e o e he p esence o CDs allows he ac i e laye o pa ially collec
also he UV ligh , inc easing he powe con e sion e iciency o he de ice.
Figu e 1.23. pho o ol aic de ice in which he CDs laye ac s as spec al con e e ( om
e . 114).
1.8. Re e ences
1. Cayuela, A.; So iano, M. L.; Ca illo-Ca ión, C.; Valcá cel, M., Semiconduc o and
ca bon-based luo escen nanodo s: he need o consis ency. Chemical Communica ions
2016, 52 (7), 1311-1326.
2. Feng, T.; Zhu, S.; Zeng, Q.; Lu, S.; Tao, S.; Liu, J.; Yang, B., Sup amolecula C oss-
Link-Regula ed Emission and Rela ed Applica ions in Polyme Ca bon Do s. ACS Applied
Ma e ials & In e aces 2018, 10 (15), 12262-12277.
3. Shah, S. N. A.; Lin, J.-M., Recen ad ances in chemiluminescence based on
ca bonaceous do s. Ad ances in Colloid and In e ace Science 2017, 241, 24-36.
4. Xu, Y.; Liu, J.; Gao, C.; Wang, E., Applica ions o ca bon quan um do s in
elec ochemiluminescence: A mini e iew. Elec ochemis y Communica ions 2014, 48, 151-
154.
5. Xu, X.; Ray, R.; Gu, Y.; Ploehn, H. J.; Gea hea , L.; Rake , K.; Sc i ens, W. A.,
Elec opho e ic Analysis and Pu i ica ion o Fluo escen Single-Walled Ca bon Nano ube
F agmen s. Jou nal o he Ame ican Chemical Socie y 2004, 126 (40), 12736-12737.
31
6. Zhou, J.; Booke , C.; Li, R.; Zhou, X.; Sham, T.-K.; Sun, X.; Ding, Z., An
Elec ochemical A enue o Blue Luminescen Nanoc ys als om Mul iwalled Ca bon
Nano ubes (MWCNTs). Jou nal o he Ame ican Chemical Socie y 2007, 129 (4), 744-745.
7. Liu, H.; Ye, T.; Mao, C., Fluo escen Ca bon Nanopa icles De i ed om Candle
Soo . Angewand e Chemie In e na ional Edi ion 2007, 46 (34), 6473-6475.
8. Hu, S.-L.; Niu, K.-Y.; Sun, J.; Yang, J.; Zhao, N.-Q.; Du, X.-W., One-s ep syn hesis
o luo escen ca bon nanopa icles by lase i adia ion. Jou nal o Ma e ials Chemis y 2009,
19 (4), 484-488.
9. Sun, Y.-P.; Zhou, B.; Lin, Y.; Wang, W.; Fe nando, K. A. S.; Pa hak, P.; Meziani, M.
J.; Ha u , B. A.; Wang, X.; Wang, H.; Luo, P. G.; Yang, H.; Kose, M. E.; Chen, B.; Veca, L.
M.; Xie, S.-Y., Quan um-Sized Ca bon Do s o B igh and Colo ul Pho oluminescence.
Jou nal o he Ame ican Chemical Socie y 2006, 128 (24), 7756-7757.
10. Zhao, Q.-L.; Zhang, Z.-L.; Huang, B.-H.; Peng, J.; Zhang, M.; Pang, D.-W., Facile
p epa a ion o low cy o oxici y luo escen ca bon nanoc ys als by elec ooxida ion o
g aphi e. Chemical Communica ions 2008, (41), 5116-5118.
11. Peng, H.; T a as-Sejdic, J., Simple Aqueous Solu ion Rou e o Luminescen
Ca bogenic Do s om Ca bohyd a es. Chemis y o Ma e ials 2009, 21 (23), 5563-5565.
12. Qiao, Z.-A.; Wang, Y.; Gao, Y.; Li, H.; Dai, T.; Liu, Y.; Huo, Q., Comme cially
ac i a ed ca bon as he sou ce o p oducing mul icolo pho oluminescen ca bon do s by
chemical oxida ion. Chemical Communica ions 2010, 46 (46), 8812-8814.
13. Gonçal es, H.; Jo ge, P. A. S.; Fe nandes, J. R. A.; Es e es da Sil a, J. C. G., Hg(II)
sensing based on unc ionalized ca bon do s ob ained by di ec lase abla ion. Senso s and
Ac ua o s B: Chemical 2010, 145 (2), 702-707.
14. Anilkuma , P.; Wang, X.; Cao, L.; Sahu, S.; Liu, J.-H.; Wang, P.; Ko ch, K.; Tacke
Ii, K. N.; Pa enzan, A.; Sun, Y.-P., Towa d quan i a i ely luo escen ca bon-based
“quan um” do s. Nanoscale 2011, 3 (5), 2023-2027.
15. Liu, Y.; Liu, C.-y.; Zhang, Z.-y., Syn hesis and su ace pho ochemis y o g aphi ized
ca bon quan um do s. Jou nal o Colloid and In e ace Science 2011, 356 (2), 416-421.
16. Sachde , A.; Ma ai, I.; Gopina h, P., Implica ions o su ace passi a ion on
physicochemical and bioimaging p ope ies o ca bon do s. RSC Ad ances 2014, 4 (40),
20915-20921.
17. Bou linos, A. B.; S assinopoulos, A.; Anglos, D.; Zbo il, R.; Ka akassides, M.;
Giannelis, E. P., Su ace Func ionalized Ca bogenic Quan um Do s. Small 2008, 4 (4), 455-
458.
18. Bou linos, A. B.; S assinopoulos, A.; Anglos, D.; Zbo il, R.; Geo gakilas, V.;
Giannelis, E. P., Pho oluminescen Ca bogenic Do s. Chemis y o Ma e ials 2008, 20 (14),
4539-4541.
19. Hsu, P.-C.; Chang, H.-T., Syn hesis o high-quali y ca bon nanodo s om hyd ophilic
compounds: ole o unc ional g oups. Chemical Communica ions 2012, 48 (33), 3984-3986.
20. Hu, S.; Tian, R.; Dong, Y.; Yang, J.; Liu, J.; Chang, Q., Modula ion and e ec s o
su ace g oups on pho oluminescence and pho oca aly ic ac i i y o ca bon do s. Nanoscale
2013, 5 (23), 11665-11671.
21. Kozák, O.; Da a, K. K. R.; G eplo á, M.; Ranc, V.; Kašlík, J.; Zbořil, R., Su ac an -
De i ed Amphiphilic Ca bon Do s wi h Tunable Pho oluminescence. The Jou nal o Physical
Chemis y C 2013, 117 (47), 24991-24996.
22. Yin, J.-Y.; Liu, H.-J.; Jiang, S.; Chen, Y.; Yao, Y., Hype b anched Polyme
Func ionalized Ca bon Do s wi h Mul is imuli-Responsi e P ope y. ACS Mac o Le e s
2013, 2 (11), 1033-1037.
38
2. ELUCIDATION OF THE
RELATIONSHIP BETWEEN
POLYMER STRUCTURE AND BLUE
FLUORESCENCE OF CARBON DOTS

39
2.1. Abs ac
The CDs ob ained by he employmen o ca boxylic acid and amine p ecu so s equen ly
show b igh blue luo escence emission, independen om he exci a ion wa eleng h. The
polyme s uc u al igidi y was ecognized o play a key ole in his phenomenon, ne e heless
he knowledge o he CDs s uc u e is s ill inadequa e o i s comp ehension. In his wo k
h ee syn he ic p ocedu es we e ca ied ou o ob ain blue luo escen CDs om ca boxylic
acids and amines. The ull elucida ion o he chemical s uc u es and hei compa ison
allowed asc ibing unequi ocally hei simila luo escen beha io s o he p esence o a
compac and en angled polyamide ne wo k. In he e, hyd ogen bond-media ed in amolecula
in e ac ions we e ound o signi ican ly enhance he polyme con o ma ional igidi y. Densi y
unc ional heo y calcula ions o his s uc u e con i med i s igid and compac na u e.
Mo eo e a pho o-induced in amolecula cha ge ans e aking place be ween amide and
ca boxylic acid moie es was ecognized as he mechanism esponsible o he luo escence
emission. Finally, he pho oinduced cha ge- ans e p ocesses could easily explain he
pe o mance o CDs in applica ions as e ealed in s udies on me al ion sensing.
2.2. In oduc ion
The mos common syn hesis p ocedu es o luo escen CDs a e gene ally ha sh, in ol ing he
hyd o he mal ea men o mic owa e i adia ion o o ganic molecules and/o polyme s.
These condi ions a e e lec ed in he he e ogeneous s uc u e o he ob ained nanopa icles,
which a e composed by andom polyme iza ion p oduc s as well as a ce ain deg ee o
ca boniza ion. Indeed, a high empe a u e he molecula p ecu so s condensa ion,
dehyd a ion and o he andom and unp edic able eac ions a e expec ed. Howe e , despi e
hei la ge a ie y and unce ain chemical s uc u e, mos o he as-p oduced CDs e eal a
unique blue luo escence emission as common uni ying ea u e. In he las yea s, some
au ho s ela ed his exci a ion-independen ype o emission o he p esence o conjuga ed
molecula luo opho es ha a e o ming on he polyme skele on du ing he syn hesis
p ocess.1-7 Ne e hless, B. Yang e al. ocused hei a en ion on he non-conjuga ed polyme
s uc u e i sel , claiming i s key- ole in he CDs luo escence. In ac i is known ha also
non-conjuga ed polyme s can display luo escence in condi ion o high s uc u al igidi y.
He e he igidi y o he polyme ne wo k, achie ed by c oss-linking, agg ega ion o
immobiliza ion dec eases he ib a ional and o a ional eedom o sub luo opho es such as
40
C=O, N=O, C=N he e oa om-con aining double bonds, acili a ing hei adia i e elaxa ion.
This p ocess goes by he name o c oss-link enhanced emission (CEE) e ec . 8-13
Un o una ely, he di icul y o assign a p ecise chemical s uc u e o CDs and he majo ole
a ibu ed o he p esence o conjuga ed ea u es di e ed he bulk o he a en ion om he
polyme con ibu ion o he CDs luo escence.
The ollowing s udy p oposes a deep in es iga ion on he o igin o he exci a ion-independen
blue luo escence ha is commonly obse ed in a huge a ie y o CDs. To his end, model
ypes o blue luo escen CDs wi h a well-de ined s uc u e, consis ing o commonly
employed ca boxylic acid and amine unc ional g oups a e syn hesized h ough mic owa e
i adia ion o a no el oom- empe a u e syn hesis ou e, exploi ing eac ions based on
ca bodiimide chemis y. All he ou es p oduced highly blue emi ing luo escen CDs, whose
compa able s uc u al cha ac e iza ion allowed o de e mine unequi ocally hei non-
conjuga ed polyme s uc u e and i s di ec ela ionship wi h he op ical p ope ies. Densi y
unc ional heo y (DFT) analysis con i med he expe imen al da a in e p e a ion and p o ided
he mechanism behind he luo escen beha io , iden i ying he o ganic g oups in ol ed.
2.3. Expe imen al Sec ion
2.3.1. Ma e ials
Ci ic acid anhyd ous (≥99.5%), ica ballylic acid (99%), e hylendiamine (99+%), N,N'-
diisop opylca bodiimide (99%), nickel (II) ni a e hexahyd a e (98.5%), i on (III) chlo ide
(97%), cobal (II) ni a e hexahyd a e (98%), zinc (II) chlo ide (≥97%), magnesium (II) ni a e
hexahyd a e (99%), calcium (II) chlo ide dihyd a e (99%), coppe (II) ni a e
hemi(pen ahyd a e) (98%), lead (II) ni a e (≥99%), me cu ium (II) ni a e hyd a e (98%),
we e used wi hou u he pu i ica ions. Dialysis ubes wi h molecula weigh cu -o
(MWCO) 0.5-1 KDa we e bough om Spec um Labs.
2.3.2. Cha ac e iza ion echniques
 The mic owa e-assis ed eac ion was pe o med in a CEM Disco e SP eac o
employed in open-ba ch modali y.
 A omic o ce mic oscopy (AFM) images we e acqui ed in ai unde ambien
condi ions using a NT-MDT Au a NTEGRA ins umen ope a ing in apping mode a
110 kHz esonance wi h Au ips HA_NC ETALON (10nm cu a u e adius). Samples
41
we e p epa ed on silica subs a es by d op cas ing o dilui e wa e solu ions. Pa icle
heigh dis ibu ion analysis was ca ied ou by using he Gwyddion so wa e.
 Size exclusion ch oma og aphy was pe o med on a sys em composed by: pump
(Izasa Scien i ic), au oma ic injec o (Izasa Scien i ic), PL aquagel column OH-mixed-
H (Agilen ) and e ac i e index de ec o T-REX (Wya Technology). The mobile
phase (0.1 M sodium ace a e) was lowed a 1ml/min a 35°C. Fo he calib a ion,
PEO/PEG polyme s we e used in he ange o 1970-44400 g/mol. The samples we e
dissol ed in he mobile phase a concen a ion a ound 1mg/ml. The DLS
measu emen s we e eco ded on a Mal e n Nano Ze asize HT, on a 10 mm pa h-
leng h plas ic cu e e.
 Elemen al analyses we e pe o med in a The mo Flash EA 1112 ins umen wi h ∼3
mg o powde samples.
 In a ed abso p ion measu emen s we e pe o med on powde samples p essed wi h
KB in o pelle s wi h a B uke Ve ex 70 spec ome e .
 1H and 13C NMR spec a we e eco ded in D2O solu ions a 25 oC on a B uke AV500
spec ome e (δ in ppm and J in Hz) a a 1H NMR ope a ing equency o 500.13
MHz. 1H and 13C NMR spec a we e e e enced using he sol en signal as an in e nal
s anda d. The assignmen o he 1H NMR signals and he co esponding 13C NMR
peaks was ca ied ou using s anda d 1H−13C edi ed-HSQC and 1H−13C HMBC (JHC =
8 Hz) 2D-expe imen s. The de e mina ion o he di usion coe icien s D (m2/s) was
pe o med a con olled empe a u e (300 K) in spinning solu ions o he
co esponding compounds in D2O (concen a ions abou 2 mM). The alues o del a
(δ) and del a (Δ) we e op imized o each sample. In he case o δ he alues ound
we e in he ange 1.7-2.0 ms, while o Δ he op imized alues anged om 0.17-0.20
s.
 X- ay pho oelec on spec oscopy (XPS) measu emen s we e aken wi h an ESCAPlus
spec ome e using a Mg anode (1253.5 eV) and a powe o 225 W. XPS da a analysis
was pe o med wi h casaXPS so wa e.
 UV/Vis abso p ion spec a we e eco ded on a Shimadzu UV-2401 PC
spec opho ome e .
 Pho oluminescence exci a ion and emission spec a we e eco ded on a Ho iba Jobin
Y on Fluo omax-P, sli s o exci a ion and emission a 1 mm. All he spec a we e
eco ded a oom empe a u e using 10 mm pa h-leng h qua z cu e e.
42
 Pico-second ime- esol ed fluo escence spec a we e measu ed by he ime-co ela ed-
single-pho on-coun ing (TCSPC) me hod on a Nano-Log spec ofluo ome e (Ho iba
JobinY on), by using a lase diode as an exci a ion sou ce (NanoLED, 375 nm) and a
UV-Vis de ec o TBX-PMT se ies (250-850 nm) by Ho iba JobinY on. Li e imes
we e e alua ed wi h he DAS6 Fluo escence-Decay Analysis So wa e.
2.3.3. Syn hesis o CDs1-3
2.3.3.1 Syn hesis p ocedu es
Syn hesis o CDs1. 2.0 g o ci ic acid monohyd a e (CA, 9.5 mmol, 1 eq.) we e dissol ed in
15 mL o ul apu e wa e . Upon addi ion o 0.64 mL o e hylenediamine (EDA, 1 equi .) he
solu ion was hea ed up o 140°C h ough mic owa e i adia ion (s i ing, open ba ch),
p o oking he e apo a ion o he wa e . The empe a u e was kep cons an o one minu e,
a e ha he i adia ion was s opped and he mix u e edissol ed in 10 mL o wa e . The
same p ocess was epea ed wo imes mo e, o a o al o h ee minu es a 140°C. The solid
p oduc was dilu ed wi h ul apu e wa e , il a ed h ough a 0.45 µm PTFE memb ane and
dialyzed agains ul apu e wa e (MWCO = 0.5-1.0 KDa, 3 days, wice a day), yielding in a
b ownish powde , wi h a yield in mass o 35%.
Syn hesis o CDs2. 2.0 g o ica ballylic acid (TA, 11.4 mmol, 1 equi .) we e dissol ed in
15 mL o ul apu e wa e . Upon addi ion o 0.76 mL o EDA (1 equi .) he solu ion was
hea ed up o 140°C h ough mic owa e i adia ion (s i ing, open ba ch), p o oking he
e apo a ion o he wa e . The empe a u e was kep cons an o 3 minu es, a e ha he
i adia ion was s opped and he mix u e cooled down. The solid p oduc was dilu ed wi h
ul apu e wa e , il a ed h ough a 0.45 µm PTFE memb ane and dialyzed agains ul apu e
wa e (MWCO = 0.5-1.0 KDa, 3 days, wice a day), yielding in a b ownish powde wi h a
yield in mass o 27%.
Syn hesis o CDs3. 1.0 g o anhyd ous ci ic acid (5.2 mmol, 1 equi .) was dissol ed in 5.0
mL o DMF. The solu ion was cooled in an ice ba h and 2.6 mL o diisop opyl ca bodiimide
(DIC, 3 equi .) we e added. Subsequen ly, 0.35 mL o EDA (1 eq.) in 5 mL o wa e we e
slowly added and he eac ion was s i ed o 30 minu es a oom empe a u e, du ing which
he mix u e u ns i s colo om sligh ly yellow o ed. The il e ed eac ion was s opped by
adding slowly du ing a ime o 3 hou s a NaOH solu ion a pH=10, un il no o ma ion o DIC-
u ea p ecipi a e was obse ed. The c ude was dilu ed in ul apu e wa e , il e ed and washed
43
wi h e hyl ace a e. Du ing hese ope a ions he coupling agen u ea byp oduc , in he o m o a
whi e p ecipi a e, was emo ed. The wa e phase was dialyzed agains ul apu e wa e
(MWCO = 0.5-1.0 KDa, 3 days, wice a day). The d y p oduc was ob ained by eeze-d ying,
wi h a yield in mass o 29 w . %. I appea s as a b ownish powde .
Scheme 2.1. (Top) eac ion o EDA wi h CA h ough wo syn he ic pa hways o o m
CDs1 and CDs3. (Bo om) eac ion o EDA wi h TA o o m CDs2.
2.3.3.2 Commen s o he syn hesis p ocedu es
 CA and EDA in a a io 1:1 we e chosen as s a ing ma e ial o he syn hesis o CDs1,
expec ing he amide bond o ma ion ia condensa ion be ween ca boxylic acid and
amine g oups. The employed eac ion condi ions a e he esul o a p e-s udy aimed o
in es iga e he e ec o he eac ion ime on he s uc u al and op ical p ope ies o he
CDs (see Appendix B).
 CDs2 a e ob ained h ough an iden ical p ocedu e, bu using TA in place o CA. The
eason is ha a high empe a u e he hyd oxyl g oup in CA could in p inciple lead o
unp edic able p oduc s. Thus, he eplacemen o CA wi h TA ensu es ha eac ions
in ol ing he –OH g oup a e excluded, while he plausible o ma ion o he amide
bond is una ec ed.
 Reac ion empe a u e is an addi ional c ucial pa ame e o keep unde con ol du ing
he syn hesis, since high empe a u es enable a wide ange o unp edic able eac ion
pa hways. Fo his eason, CDs3 is achie ed by amide bond o ma ion a oom
empe a u e, selec i ely ca alyzed by a ca bodiimide coupling agen .

44
 All he wa e solu ions o he h ee p oduc s display blue pho oluminescence when
i adia ed by UV-ligh .
Figu e 2.1. Pho og aphs o CDs1, CDs2 and CDs3 in solid and in wa e solu ion (0.5
mg/mL), wi h and wi hou UV i adia ion.
45
2.4. Resul s and discussion
2.4.1. Size de e mina ion o CDs1-3
The h ee samples we e analyzed by AFM (Figu e 2.2), DLS (Figu e 2.3) and DOSY (Figu e
2.4, Table 2.1), inding ha hey a e composed o nanopa icles o a ound 1.0-1.6 nm.
Figu e 2.2. AFM images o CDs1 (a), CDs2 (b), CDs3 (c) and hei espec i e heigh
dis ibu ion (d) in black, blue and ed, espec i ely. The a e age heigh is ound a
a ound 1 nm o all he samples.
Figu e 2.3. DLS size dis ibu ion o CDs1 (black), CDs2 (blue), CDs3 ( ed). All he
samples show a diame e o abou 1 nm.
46
Figu e 2.4. DOSY spec a o CDs1, CDs2, and CDs3.
The hyd odynamic adius ( H) was calcula ed h ough he S okes-Eins ein equa ion (Annex
A, ), and anges om 1.2 o 1.6 nm o all he h ee samples (Table 2.1)
Table 2.1. Measu ed di usion coe icien (D), calcula ed hyd odynamic adius ( H) and
diame e o CDs1, CDs2, and CDs3. All samples show a diame e be ween 1.2-1.6 nm.
𝐷 (m2/s)
H (nm)
Diame e (nm)
CDs1
10-9.4
0.6
1.2
CDs2
10-9.4
0.6
1.2
CDs3
10-9.5
0.8
1.6
47
2.4.2. Op ical p ope ies o CDs1-3
The op ical p ope ies o CDs1, CDs2 and CDs3 we e in es iga ed by UV/Vis spec oscopy
(Figu e 2.5a), s eady s a e pho oluminescence spec oscopy (Figu e 2.5b,c) and ime- esol ed
pho oluminescence spec oscopy (Figu e 2.6a). A peculia abso p ion band in he ange o 350
- 390 nm appea s in he UV/Vis spec a o he h ee ypes o CDs, which is di ec ly ela ed o
he pho oluminescence emission. In ac , he maximum emission in ensi y, ound a 445 nm
o CDs1 and CDs3 and a 470 nm o CDs2, is achie ed by exci ing exac ly in he same
egion (360-390 nm depending on he CDs sample, see Figu e 2.5b). Rema kably, emission
spec a o CDs1, CDs2 and CDs3 aken a di e en exci a ion wa eleng hs do no e eal a
wa eleng h dependency (Figu e 2.5c). Al hough small shi s o he maximum posi ion a e
ound be ween he di e en ypes o CDs, hei abso bance, exci a ion and emission a e
highly compa able and can be ela ed o he same adia i e p ocess.
Figu e 2.5. (a) UV/Vis, (b) Exci a ion and emission spec a o CDs1 (black), CDs2 (blue)
and CDs3 ( ed). (c) Emission in CDs1-3 a di e en exci a ion wa eleng hs.
54
Figu e 2.12. (a) 1H NMR. (b) APT 13C NMR, (c) 1H-13C HSQC and (d) 1H-13C HMBC
spec a o CDs3. (e) one o he possible chain isome s o he CDs2 epe i i e uni , wi h C
and H assigna ion.
NMR in e p e a ion o CDs2: 1H NMR. Hb: 3.8-3.3 ppm ( ), EDA 3.25 ppm (s), Hc: 3.2-
3.0 ppm (m), Ha: 3.2-2.3 ppm (s o d). APT 13C NMR shows in-phase signals, belonging o
seconda y o qua e na y ca bons. APT also shows an an iphased signal, assigned o C3, a
abou 36 ppm. C1: 184-171 ppm, C2 and C4: 40-32 ppm, C3: 38-34 ppm. 1H-13C HSQC
shows he 1J coupling o Ha, Hb and Hc wi h C2, C4 and C3 espec i ely. 1H-13C HMBC
shows he 2J o Ha wi h C3, he 2J coupling o Hc wi h C1 and C2, he 2J and 3J coupling o
Ha wi h C1 and C2, he 3J coupling o Hc wi h C1 and he 3J coupling o Hb wi h C1 and C4.

55
Figu e 2.13. (a) 1H NMR. (b) APT 13C NMR, (c) 1H-13C HSQC and (d) 1H-13C HMBC
spec a o CDs3. (e) one o he possible chain isome s o he CDs3 epe i i e uni , wi h C
and H assigna ion.
NMR in e p e a ion o CDs2: 1H NMR. Hb: 4.0-3.2 ppm (m), EDA 3.35 ppm (s), Ha: 3.2-
2.4 ppm (s o d). APT 13C NMR shows in-phase signals, belonging o seconda y o qua e na y
ca bons. C1: 182-171 ppm, C2 and C4: 47-35 ppm, C3: 76-71 ppm. 1H-13C HSQC shows he
1J coupling o Ha and Hb wi h C2 and C4 espec i ely. 1H-13C HMBC shows he 2J o Ha
wi h C3, he 2J and 3J coupling o Ha wi h C1 and C2, he 3J coupling o Hb wi h C1 and C4.
N-acyl DIC u ea side-p oduc has o med in li le amoun du ing he eac ion, inco po a ed
in o he CDs5 s uc u e (1H NMR: 1.20, 1.32, 6.72 ppm, in APT: 137, 21 ppm). Some o he
p o on signals o CDs3 a e igh -shi ed wi h espec o CDs1, p obably because o he
di e en cha ged o m due o he inal addi ion o NaOH.
56
Despi e he di e ences in he syn hesis me hods, he NMR p o iles o CDs1 and CDs3 a e
ema kably simila , showing ha in bo h cases he same ype o polyme s uc u e is ob ained.
The NMR spec a o CDs2 a e also highly compa able, aking in o accoun he di e ences
due o he absence o he hyd oxyl g oup. Me ging he in o ma ion ob ained om all he
NMR expe imen s, he chemical s uc u e o CDs1, CDs2 and CDs3 is unambiguously
iden i ied as a non-conjuga ed polyme consis ing o he p oduc o condensa ion o CA and
EDA o CDs1 and CDs3, and o TA and EDA o CDs2. The compa ison o he NMR
spec a also p o es ha unassigned mino ea u es, speci ic o each one o he employed
syn he ic ou e, a e no common o all he samples, and hus canno o m he basis o he
luo escen beha io . Fu he mo e, NMR expe imen s p o ided aluable in o ma ion
ega ding he con o ma ion o he polyme ic do s. In he 1H NMR spec a, he sha p lineshape
o he peaks (single s and iple s) s ongly sugges s a compac and s a ic s uc u e, in as
mo ion wi h espec o he ime o esponse o he echnique. The 1H-13C HSQC spec a show
ha he me hylene ca bons couple wi h a a he condensed se o p o on signals. The high
densi y o sha p signals is ela ed o he a ie y o s a ic chemical en i onmen s ha su ounds
hese p o ons and can be explained wi h he p esence o a ious chain isome s o he
epe i i e uni ha coexis in he polyme , as well as wi h he exis ence o di e en ionized
o ms. These da a highligh he b anched and igid con o ma ion o he polyme ic CDs.
2.4.4. DFT and TDDFT calcula ions
In o de o achie e a deepe unde s anding o he s uc u e and pho oluminescence o hese
nanopa icles, DFT calcula ions ha e been pe o med based on he CDs1 and CDs3
polyme ic [C8H12O5N2]n uni s (see Annex B o de ails). Fo he analysis o he s uc u al
ea u es ha may be esponsible o he CEE e ec , clus e s o di e en size ha e been
s udied, in pa icula he dime (n = 2), oc ame (n = 8) and decame (n = 10). The la e is a
good app oxima ion o he CDs1 eal chain, whose molecula mass was measu ed o be 2300
Da by size exclusion ch oma og aphy (SEC/RI, Annex B), while he polyme ic uni weigh s
216 Da. The op imized s uc u es show ha he main cha ac e is ic is a e y in ica e ne wo k
due o he es ablishmen o bo h in a- and in e molecula hyd ogen bonds. In Figu e 2.14a
wo dime ic chains (n = 2) a e ep esen ed and i is clea he deg ee o en anglemen , bo h
wi hin and be ween chains. In Figu e 2.14b is ep esen ed one decame ic chain (n = 10) ha
also shows a highly in ica e s uc u e due o he in amolecula hyd ogen bonding (HB). This
ea u e is e lec ed in he size o he nanopa icle. The calcula ed diame e s a e 1.564 nm and
57
1.670 nm o he oc ame and he decame , espec i ely, in good ag eemen wi h he pa icle
size measu ed expe imen ally.
Figu e 2.14. Op imized molecula s uc u es o (a) wo dime (n = 2) chains and (b) one
decame (n =10) chain. (c) HOMO and (d) LUMO molecula o bi als in ol ed in he
luo escence phenomenon.
As i has been p e iously men ioned, his agg ega ion o he chains is esponsible o he
enhancemen o he luo escence in hese sys ems, due o a es ic ion o he ib a ional o
o a ional deg ees o eedom ha may a o a non- adia i e elaxa ion. In o de o
co obo a e his s a emen , he op ical p ope ies o ou ep esen a i e sys ems ha e been
calcula ed, namely, h ee dime s and one oc ame . The i s dime has only one chain, while
he o he s comp ise wo dime ic chains o gene a e wo con o me s, whe e ei he he
in amolecula o he in e molecula HB is a o ed. The use o one o wo chains, as well as
wo di e en con o me s, allows s udying he in luence o he in a- and in e molecula
in e ac ions independen ly. The oc ame has been used in o de o elie e he compu a ional
e o . In Table 2.3 a e ga he ed he abso p ion and emission ene gies, and he co esponding
wa eleng hs.
58
Table 2.3. Abso p ion (Eabs) and emission (Eem) ene gies
Eabs (eV)
Eem (eV)
Dime (one chain)
5.1811
---
Dime o wo chains
(HB in amolecula )
4.8794
---
Dime o wo chains
(HB in e molecula )
5.1382
1.8317
Oc ame
4.6142
1.9602
I is obse ed ha he ou models abso b in he UV, wi h wa eleng hs in he ange o abs =
239 – 269 nm. The na u e o he ansi ion has been cha ac e ized by he analysis o he
molecula o bi als in ol ed, which is depic ed in Figu es 2.14c and 2.14d o he dime , in
o de o acili a e he isualiza ion. The HOMO has i s main con ibu ion om he amide
moie y (-CONH-), while he LUMO is cen e ed in he ca boxylic g oups (-COOH) and i is
om HOMO o LUMO whe e exci a ion akes place. This means ha HOMO and LUMO
molecula o bi als a e con ined a e y speci ic si es, ha hey a e well sepa a ed, and ha he
luo escence is a cha ge ans e p ocess. This p ocess is enhanced o he la ge models due o
he sum o all local cha ge ans e p ocesses occu ing in each amide-ca boxyl pai o he
chain. Expe imen al e idence o hese indings is p o ided by he esul s o ou
pho oluminescence s udies. Fi s , he la ge S okes-shi o abou 1 eV (see Figu e 2.5b) should
be ela ed o a conside able change in he dipole momen be ween g ound s a e and exci ed
s a e, being consis en wi h he ypical pho o-induced cha ge ans e mechanism.54-57 Second,
he p o ona ion dependency o he emission in ensi y (see Figu e 2.7) e eals he impo an
ole o he ca boxylic acids in he luo escence p ocess: They a ec he igidi y o he o e all
polyme ne wo k s uc u e ia hyd ogen bonding o elec os a ic in e ac ions, as discussed
abo e. Concomi an ly, hey ac as elec on accep o in he cha ge ans e p ocess. The
obse a ion o a s ong decay o he luo escence in an acidic en i onmen is a consequence
o he weakening o he ca boxyl acids in amolecula in e ac ions, which c ea e he emi ing
s a e (see Figu e 2.14c,d). On he con a y, s eng hening he ca boxylic in amolecula chain
in e ac ions, as ob ained unde neu al and basic condi ions, leads o he eco e y o he
ca boxylic acids in amolecula chain in e ac ions, a o ing cha ge- ans e and he
luo escence p ocess.
Rega ding he emission, a s iking beha io is ound. Bo h he dime wi h one chain and ha
wi h wo chains whe e he main in e ac ion is he in amolecula HB, show ansi ions ha a e
59
ema kably edshi ed. In ac , he emission akes place in a egion whe e he single exci ed
s a e and he g ound s a e po en ial ene gy su aces c oss, known as in e nal con e sion (IC),
in ol ing a non- adia i e elaxa ion and, hence, no luo escence will be obse ed.
Conside ing he dime wi h wo chains, in which he in e molecula HB is a o ed, a clea
edshi o he emission ene gy is obse ed wi h espec o he abso p ion, a ising om a
single exci ed s a e well sepa a ed om he g ound s a e (1.8317 eV abo e he g ound s a e).
This emission akes place in he isible egion (em = 676.9 nm). These esul s sugges ha , in
a small chain like a dime , he c osslink gene a ed by he in amolecula HB is no enough o
a oid he non- adia i e elaxa ion by ib a ion o o a ion o he chain, and he main
con inemen is exe ed by he in e molecula in e ac ions. Ne e heless, his p ominen
ea u e disappea s when longe chains a e conside ed and a la ge numbe o in amolecula
in e ac ions a e allowed. Thus, inspec ing he esul s o he oc ame (single chain), a simila
edshi is obse ed and he emission also ake place in he isible (em = 632.5 nm). This
means ha he in amolecula c osslink is s ong enough o hinde he ib a ion and o a ion
o he chain, and luo escence is obse ed. A his poin i is wo hwhile o ou line ha he
heo e ical calcula ions a e based on simpli ied models, which do no ake in o accoun
se e al e ec s o expe imen al ele ance, such as polyme b anching, in luence o addi ional
chains, sol en e ec s, no hose ela ed o he p esence o ee amines o cha ged s a es.
These pa ame e s con ibu e o enhance he igidi y o he polyme and hus may lead o
u he impo an down shi s o he calcula ed emission wa eleng hs owa ds he blue
wa eleng h ange. Impo an ly, despi e quan i a i e sho alls, ou models ye p o ide a solid
base o quali a i ely explain he o igin o he luo escence o he CDs.
2.4.5. In e p e a ion o he CDs sensing abili y
The iden i ica ion o cha ge- ans e p ocesses be ween well-de ined and spa ially sepa a ed
unc ional g oups as o igin o he luo escence in polyme CDs now p o ides a powe ul
oolbox owa ds an imp o ed unde s anding o hei use in echnological applica ions. This is
demons a ed a hand o s udies on he sensing o me al ions in aqueous solu ions. To his end,
he luo escence o an aqueous solu ion o CDs3 (0.4 mg/mL) was measu ed in he p esence
o se e al ypes o me al ions a a concen a ion o 1mM. A high a ini y (i.e. high quenching
a e) owa ds Fe3+, Cu2+, and Hg2+, and o he ypes o me al ions o a lowe con en is
obse ed (Figu e 2.15). Simila esul s we e ob ained o CDs1 and CDs2, which a e also in
ag eemen wi h hose obse ed o CDs o unknown chemical s uc u e.58-60 These indings

60
clea ly con i m ha he high sensi i i y can be asc ibed o he common chemical s uc u e o
polyme CDs. In ac , he same g oups iden i ied o be in ol ed in he cha ge ans e p ocess
can ac also as chela ing agen s, in a simila way o EDA, EDTA and ci a e. Ca boxylic acids,
amides and amines a e he e o e in e ac ing s ongly wi h he me al ions and he binding
p o ides a o able non- adia i e elaxa ion pa hways, which compe e wi h he in amolecula
cha ge- ans e p ocess and d as ically educe he pho oluminescence emission. This s udy no
only p o es he exis ence o pho oinduced cha ge- ans e p ocesses be ween spa ially
sepa a ed amide and ca boxylic moie ies in polyme CDs, bu also explains how o
success ully exploi his mechanism in o he ypes o applica ions o echnological ele ance.
Figu e 2.15. (a) Rela i e luo escence in ensi y o CDs3 whe e I and Io a e he in ensi ies
in p esence and absence o he me al ions. (b) Emission spec a o a CDs3 wa e solu ion
in he p esence o 1mM concen a ion o Mg2+, Ca2+, Fe3+, Pb2+, Ni2+, Cu2+, Ag2+, Zn2+,
Co2+, Hg2+.
61
2.5. Conclusion
The syn hesis o blue luo escen model polyme CDs was ob ained om CA and EDA as
well as om TA and EDA by mic owa e i adia ion, and om CA and EDA by a no el
coupling agen -media ed condensa ion a oom empe a u e. The op ical ea u es o he h ee
ypes o model CDs o 1 – 1.5 nm in size a e ema kably simila , sugges ing ha he
copolyme iza ion o he eagen s by amide bond is a su icien condi ion o he o ma ion o
he luo opho e in polyme CDs. This hypo hesis was u he con i med by a de ailed
s uc u al cha ac e iza ion o he ma e ials, which e ealed ha he p esence o H-bonds and
elec os a ic in e ac ions goes along wi h he high con o ma ional igidi y o he polyme ic
chain. DFT and TDDFT calcula ions o he oc ame o his s uc u e indeed show ha
sup amolecula H-bond media ed in e ac ions cause he igid en anglemen o he chains,
hinde ing ib a ion and o a ion, and acili a e he adia i e elaxa ion p ocess. Finally, he
amide and he ca boxylic g oups a e ecognized as he moie ies, which espec i ely p o ide
he main con ibu ion o he HOMO and he LUMO molecula o bi als. Pho oinduced cha ge-
ans e be ween hese spa ially sepa a ed g oups, assis ed by H-bond media ed
sup amolecula in e ac ions in he en angled polyamide ne wo k he e o e is iden i ied as
o igin o he luo escence phenomena in polyme ca bon do s.
Figu e 2.16. Illus a ion o he CDs o ma ion and o he pho o-induced cha ge ans e
phenomenon.
I is p oposed ha his single emi e ype p ocess p o ides a uni e sal explana ion o he
CDs’ blue luo escence obse ed in he as and inc easing amoun o epo s whe e hese
62
nanopa icles a e p epa ed om ca boxylic acids and amines. Howe e , his p ocess becomes
masked by he con ibu ion o addi ional luo escen emi e s, ypically ob ained when
employing ha she condi ions, esul ing in an exci a ion dependen emission beha io .
Addi ionally hese indings explain he pe o mance o polyme CDs in exis ing echnological
applica ions. Mo eo e , i pa es he way o exploi no el syn he ic bo om-up ou es o ob ain
polyme CDs wi h ailo ed p ope ies unco e ing ye unexploi ed oppo uni ies.
2.6. Re e ences
1. Song, Y.; Zhu, S.; Zhang, S.; Fu, Y.; Wang, L.; Zhao, X.; Yang, B., In es iga ion om
chemical s uc u e o pho oluminescen mechanism: a ype o ca bon do s om he py olysis
o ci ic acid and an amine. Jou nal o Ma e ials Chemis y C 2015, 3 (23), 5976-5984.
2. Zhu, S.; Zhao, X.; Song, Y.; Lu, S.; Yang, B., Beyond bo om-up ca bon nanodo s:
Ci ic-acid de i ed o ganic molecules. Nano Today 2016, 11 (2), 128-132.
3. Dhenadhayalan, N.; Lin, K.-C.; Su esh, R.; Ramamu hy, P., Un a elling he Mul iple
Emissi e S a es in Ci ic-Acid-De i ed Ca bon Do s. The Jou nal o Physical Chemis y C
2016, 120 (2), 1252-1261.
4. Schneide , J.; Reckmeie , C. J.; Xiong, Y.; on Seckendo , M.; Susha, A. S.; Kasák,
P.; Rogach, A. L., Molecula Fluo escence in Ci ic Acid-Based Ca bon Do s. The Jou nal o
Physical Chemis y C 2017, 121 (3), 2014-2022.
5. Shi, L.; Yang, J. H.; Zeng, H. B.; Chen, Y. M.; Yang, S. C.; Wu, C.; Zeng, H.;
Yoshihi o, O.; Zhang, Q., Ca bon do s wi h high luo escence quan um yield: he luo escence
o igina es om o ganic luo opho es. Nanoscale 2016, 8 (30), 14374-14378.
6. Fang, Q.; Dong, Y.; Chen, Y.; Lu, C.-H.; Chi, Y.; Yang, H.-H.; Yu, T., Luminescence
o igin o ca bon based do s ob ained om ci ic acid and amino g oup-con aining molecules.
Ca bon 2017, 118, 319-326.
7. Eh a , F.; Bha acha yya, S.; Schneide , J.; Lö , A.; Wy wich, R.; Rogach, A. L.;
S ola czyk, J. K.; U ban, A. S.; Feldmann, J., T acking he Sou ce o Ca bon Do
Pho oluminescence: A oma ic Domains e sus Molecula Fluo opho es. Nano Le e s 2017,
17 (12), 7710-7716.
8. Zhu, S.; Song, Y.; Zhao, X.; Shao, J.; Zhang, J.; Yang, B., The pho oluminescence
mechanism in ca bon do s (g aphene quan um do s, ca bon nanodo s, and polyme do s):
cu en s a e and u u e pe spec i e. Nano Resea ch 2015, 8 (2), 355-381.
9. Zhu, S.; Song, Y.; Shao, J.; Zhao, X.; Yang, B., Non-Conjuga ed Polyme Do s wi h
C osslink-Enhanced Emission in he Absence o Fluo opho e Uni s. Angewand e Chemie
In e na ional Edi ion 2015, 54 (49), 14626-14637.
10. Zhao, E.; Lam, J. W. Y.; Meng, L.; Hong, Y.; Deng, H.; Bai, G.; Huang, X.; Hao, J.;
Tang, B. Z., Poly[(maleic anhyd ide)-al -( inyl ace a e)]: A Pu e Oxygenic Nonconjuga ed
Mac omolecule wi h S ong Ligh Emission and Sol a och omic E ec . Mac omolecules
2015, 48 (1), 64-71.
11. Qiao, Z. A.; Huo, Q.; Chi, M.; Vei h, G. M.; Binde , A. J.; Dai, S., A "ship-in-a-
bo le" app oach o syn hesis o polyme do s@silica o polyme do s@ca bon co e-shell
nanosphe es. Ad Ma e 2012, 24 (45), 6017-21.
12. Tao, S.; Song, Y.; Zhu, S.; Shao, J.; Yang, B., A new ype o polyme ca bon do s
wi h high quan um yield: F om syn hesis o in es iga ion on luo escence mechanism.
Polyme .
63
13. Tao, S.; Lu, S.; Geng, Y.; Zhu, S.; Red e n, S. A. T.; Song, Y.; Feng, T.; Xu, W.;
Yang, B., Design o Me al-F ee Polyme Ca bon Do s: A New Class o Room-Tempe a u e
Phospho escen Ma e ials. Angewand e Chemie In e na ional Edi ion 2018, 57 (9), 2393-
2398.
14. Xiao, Q.; Liang, Y.; Zhu, F.; Lu, S.; Huang, S., Mic owa e-assis ed one-po syn hesis
o highly luminescen N-doped ca bon do s o cellula imaging and mul i-ion p obing.
Mic ochimica Ac a 2017, 184 (7), 2429-2438.
15. Gao, F.; Ma, S.; Li, J.; Dai, K.; Xiao, X.; Zhao, D.; Gong, W., Ra ional design o high
quali y ci ic acid-de i ed ca bon do s by selec ing e icien chemical s uc u e mo i s.
Ca bon 2017, 112, 131-141.
16. Zhang, Y.; Wang, Y.; Feng, X.; Zhang, F.; Yang, Y.; Liu, X., E ec o eac ion
empe a u e on s uc u e and luo escence p ope ies o ni ogen-doped ca bon do s. Applied
Su ace Science 2016, 387, 1236-1246.
17. Xu, Z.-Q.; Lan, J.-Y.; Jin, J.-C.; Dong, P.; Jiang, F.-L.; Liu, Y., Highly
Pho oluminescen Ni ogen-Doped Ca bon Nanodo s and Thei P o ec i e E ec s agains
Oxida i e S ess on Cells. ACS Applied Ma e ials & In e aces 2015, 7 (51), 28346-28352.
18. He, J.; Zhang, H.; Zou, J.; Liu, Y.; Zhuang, J.; Xiao, Y.; Lei, B., Ca bon do s-based
luo escen p obe o “o -on” sensing o Hg(II) and I−. Biosenso s and Bioelec onics 2016,
79, 531-535.
19. Ogi, T.; Aishima, K.; Pe ma asa i, F. A.; Iskanda , F.; Tanabe, E.; Okuyama, K.,
Kine ics o ni ogen-doped ca bon do o ma ion ia hyd o he mal syn hesis. New Jou nal o
Chemis y 2016, 40 (6), 5555-5561.
20. Zhang, F.; Feng, X.; Zhang, Y.; Yan, L.; Yang, Y.; Liu, X., Pho oluminescen ca bon
quan um do s as a di ec ly ilm- o ming phospho owa ds whi e LEDs. Nanoscale 2016, 8
(16), 8618-8632.
21. Rong, M.; Feng, Y.; Wang, Y.; Chen, X., One-po solid phase py olysis syn hesis o
ni ogen-doped ca bon do s o Fe3+ sensing and bioimaging. Senso s and Ac ua o s B:
Chemical 2017, 245, 868-874.
22. Bha acha yya, S.; Eh a , F.; U ban, P.; Te es, R.; Wy wich, R.; Döblinge , M.;
Feldmann, J.; U ban, A. S.; S ola czyk, J. K., E ec o ni ogen a om posi ioning on he ade-
o be ween emissi e and pho oca aly ic p ope ies o ca bon do s. Na u e Communica ions
2017, 8 (1), 1401.
23. Baghe i, Z.; Eh esabi, H.; Rahmandous , M.; Ahadian, M. M.; Hallaji, Z.; Eskanda i,
F.; Joka , E., New Insigh in o he Concep o Ca boniza ion Deg ee in Syn hesis o Ca bon
Do s o Achie e Facile Sma phone Based Sensing Pla o m. Scien i ic Repo s 2017, 7 (1),
11013.
24. Tong, G.; Wang, J.; Wang, R.; Guo, X.; He, L.; Qiu, F.; Wang, G.; Zhu, B.; Zhu, X.;
Liu, T., Amo phous ca bon do s wi h high wo-pho on luo escence o cellula imaging
passi a ed by hype b anched poly(amino amine). Jou nal o Ma e ials Chemis y B 2015, 3
(4), 700-706.
25. Liu, Y.; Zhou, L.; Li, Y.; Deng, R.; Zhang, H., Facile syn hesis o ni ogen-doped
ca bon do s wi h obus luo escence in a s ongly alkaline solu ion and a e e sible
luo escence 'o -on' swi ch be ween s ongly acidic and alkaline solu ions. RSC Ad ances
2016, 6 (110), 108203-108208.
26. Yang, M.; Li, B.; Zhong, K.; Lu, Y., Pho oluminescence p ope ies o N-doped ca bon
do s p epa ed in di e en sol en s and applica ions in pH sensing. Jou nal o Ma e ials
Science 2018, 53 (4), 2424-2433.
27. Zhang, W.; Shi, L.; Liu, Y.; Meng, X.; Xu, H.; Xu, Y.; Liu, B.; Fang, X.; Li, H.-B.;
Ding, T., Sup amolecula in e ac ions ia hyd ogen bonding con ibu ing o ci ic-acid
70
wi h he me hylenes in he 1H-13C HMBC spec a bu no in he 1H-13C HSQC spec a.
Ga he ing all hese s uc u al in o ma ion, i appea s clea ha all he ou me hods employed
accomplished he syn hesis o polyme nanopa icles whose s uc u e consis s o he
condensa ion p oduc s be ween CA ca boxylic acids and EDA amines. In spi e o he
s uc u al simila i y, an in es iga ion o he CDs 1a-1d op ical p ope ies showed ha he
luo escence in ensi y depends conside ably on he syn he ic me hod. UV/Vis spec a o CDs
1a, CDs 1b and CDs 1d p esen an abso p ion band a 340 nm, while o CDs 1c he same
ea u e has i s maximum a 310 nm (Figu e 3.1a). P obably in CDs 1c he shi is no eal, due
o he ac ha he conside ed abso p ion band is e y small wi h espec o he abso p ion o
he C=O g oups a <300 nm. The emi ing beha io o he ou samples shows indeed a
co ela ion wi h he quan um yield (QY). In CDs 1a (QY=17.7%) and 1b (QY=8.6%) he
emission akes place a ound 445 nm and is app oxima ely independen om he exci a ion,
while in CDs 1c and 1d he QY is ema kably lowe ( espec i ely 2.2% and 4.0%) and he
emission is exci a ion-dependen (Figu e 3.1b). These obse a ions sugges ha he main
con ibu ion o he luo escence in ensi y is independen om he exci a ion. Addi ionally
some e ec s p oduce he exci a ion dependency in all he samples. Howe e , hei in luence
only becomes no iceable when he main abso p ion con ibu ion is weak, as in he case o
CDs 1c and 1d. The exci a ion dependency in hese cases could be asc ibed o he e ogenei y
o he emi ing cen e s, possibly due o c osslinking o agg ega ion e ec s14.

71
Figu e 3.1. a) abso p ion spec a o CDs 1a-d. b) emission o CDs 1a-d o di e en
exci a ion wa eleng hs.
Once a es ed ha he DIC- and EDC-media ed condensa ion a e, among he me hods
conside ed, he mos e ec i e o he syn hesis o highly luo escen nanopa icles om CA
and EDA, he same p ocedu e was es ed employing di e en alipha ic and a oma ic
polyamines in he place o EDA, again in a a io 1:1 wi h espec o CA. In his way he
syn hesis o CDs 2a- was accomplished (Scheme 3.2, Table 3.1).
72
Scheme 3.2. Syn hesis o CDs 2a- .
Table 3.1. amines employed o he polycondensa ion, emission maximum, QY and
pic u es (in wa e , UV ligh o and on) o CDs 2a- .
The as-p oduced ma e ials CDs 2a- we e cha ac e ized by AFM (Figu e 9.32) and DOSY
(Figu e 9.33 and Table 9.3). Acco dingly o bo h echniques, all he samples consis o
nanopa icles o size comp ised be ween 1.0 and 2.5 nm, wi h he excep ion o CDs 2c, which
shows a size o a ound 2 nm by AFM, bu o 4.8 nm by DOSY. The as-p oduced ma e ials
we e cha ac e ized by elemen al analysis, IR and NMR spec oscopy. Also o CDs 2a-c, he
C, H, N and O pe cen ages s ongly sugges ha he o med copolyme s a e made o a a io
1:1 be ween CA and he employed amine (Tables 9.4-9.6 and Figu es 9.34-9.36), while his
s oichiome y is no espec ed o CDs 2d- , p esumably due o he lowe and co-dependen
eac i i y o he a oma ic di-amines (Table 9.7 and Figu e 9.37), bu also o he p esence o
unknown impu i ies (Figu es 9.56, 9.60, 9.64). IR spec a (Figu es 9.38-9.43) show C=O
73
s e ching o ca boxylic acids and amides, as p e iously obse ed o CDs 1a-d. Mo eo e
CDs 2d- p esen he ypical a oma ic C=C s e ching be ween 1516-1497 cm-1 (Figu es 9.41-
9.43). Finally, 1H, 13C APT, 1H-13C HSQC and 1H-13C HMBC expe imen s con i med he
copolyme connec i i y ia amide as he esul s o he condensa ion be ween ci ic acid and
he espec i e amine (Figu es 9.44-9.67). Fo CDs 2d- a e also well isible he a oma ic
signals, be ween 7.5-6.5 ppm in he p o on spec a and 147-109 ppm in he ca bon spec a.
The ac ha he esul s o he s uc u al cha ac e iza ion conclusi ely con i m he expec ed
polyamide s uc u es emphasizes he e sa ili y o ou syn he ic p ocedu e. Conce ning he
op ical p ope ies o CDs 2a- , i can be obse ed ha he emission wa eleng h does no
change consis en ly wi h he amine employed and i is ound be ween 433 and 452 nm
depending on he sample (Figu es 9.69-9.74). On he o he hand he QY o CDs 2a-c, wi h
alipha ic amines, is highe han in CDs 2d- , wi h a oma ic amines (Table 3.1). I is
easonable o say ha he polyme con o ma ion esponsible o he adia i e decay can be
hampe ed by he locked con igu a ion o he amines in o-, m- o p- posi ion. Among hese, o-
posi ion could be he mos a o able, esembling one o he EDA con o ma ions, and in ac
CDs 2d QY is highe han CDs 2e QY, which in u n is highe han he one o CDs 2 , whose
subs i uen s do no allow he compac olding needed o he o ma ion o he luo opho e.
The inding ha he polycondensa ion ca alyzed by ca bodiimides can be success ully
exploi ed o he syn hesis o di e en luo escen nanopa icles as a unc ion o he ype o
amine g oup employed, allowing hus he con ol on he inal chemical s uc u e, p o ided a
unique oppo uni y o pe o m an addi ional s udy es ing he possibili y o unc ionalize in-
si u he as-p oduced ma e ials. Since he g ow h o he nanopa icles is media ed by he
ac i a ion o he ca boxylic acids ia coupling agen s, i can be in e up ed a any momen
adding an excess o a s ong nucleophile. In he p e ious expe imen s, NaOH was used o
es o e he ca boxylic acids and quench he polyme iza ion. Ne e heless, p ima y amines a e
equally good candida es o his pu pose. Mo eo e , he employmen o an amine o e s he
possibili y o a ach on o he su ace o he CDs i ually any moie y ha is s able and soluble
in he eac ion medium. The in-si u unc ionaliza ion was es ed by he addi ion o i e
di e en p ima y amines du ing he polycondensa ion eac ion be ween CA and EDA
media ed by DIC (Scheme 3.3, Table 3.2).
74
Scheme 3.3. a) polycondensa ion o CA and EDA media ed by coupling agen . b) he
addi ion o a p ima y amine consumes he ac i a ed ca boxylic acids and s ops he
polyme iza ion.
Table 3.2. amine employed o he unc ionaliza ion, emission maximum, QY and
pic u es (in wa e , UV ligh o and on) o CDs 3a-e.
Simila ly o CDs 1a-d, CDs 3a-e e eal sizes be ween 1.0-2.6 nm, as p obed by AFM (Figu e
9.76) and DOSY (Figu e 9.77, Table 9.8). The s uc u al cha ac e iza ion p o ed he e ec i e
unc ionaliza ion. Elemen al analysis shows ha he unc ionalized ma e ials CDs 3a-e
p esen lowe mola pe cen ages o oxygen compa ed o CDs 1a, as a consequence o he
success ul unc ionaliza ion (Table 9.9 and Figu e 9.78). In pa allel, in he in a ed spec a o
CDs 3a-3d (Figu es 9.79-9.83) he ca boxylic acid C=O s e ching a 1704 cm-1 is weake
han in CDs 1a o no isible, due o he consump ion o he majo i y o he ca boxyl g oups
by means o he unc ionaliza ion. In CDs 3e his e ec is no app eciable because o he
75
p esence o he ca bama e C=O s e ching band, which is ound a simila wa enumbe s o
he ca boxylic one. Addi ionally i is obse ed in CDs 3c he C=C s e ching a 1545 cm-1 due
o he a oma ic ing. 1H, 13C APT, 1H-13C HSQC and 1H-13C HMBC expe imen s con i med
he in oduc ion on CDs 3a-3e o he co esponding unc ionali ies (Figu es 9.84-9.103). The
pe o med s uc u al modi ica ions only sligh ly a ec he abso p ion (Figu e 9.104) and
emission maximum posi ion (Figu es 9.105-9.109), meaning ha hey a e no di ec ly
in ol ed in he luo escence mechanism. Howe e di e en QY a e ob ained depending on
he unc ionaliza ion. Rigid and bulky g oups, such as in CDs 2c and 3d, dec ease he
luo escence in ensi y. In con as , he QY bene i s om he hiol unc ionaliza ion, possibly
due o i s in ol emen in he H-bond in e ac ions ha play a ole in he o ma ion o he
polyme con o ma ion needed o he ob aining o he luo escen beha io .
3.5. Conclusion
In summa y, we illus a ed he e sa ili y o a no el app oach o he syn hesis o luo escen
CDs, consis ing in he coupling agen -media ed condensa ion be ween ci ic acid and amines
a oom empe a u e. This s a egy enables he syn hesis o a wide a ie y o polyme ic
nanopa icles whose chemical s uc u e is de e mined only by he choice o he eagen s.
Fu he mo e, he me hod allows he in-si u unc ionaliza ion o he CDs, supplying an
addi ional le el o con ol on he inal chemical s uc u e and a oiding u he
unc ionaliza ion s eps o he wise needed o many applica ions. The e o e his me hod
p o ides an easy and e icien pa hway o con olling he s uc u e and he chemical
p ope ies o he polyme nanopa icles, u nishing an ex emely e sa ile ool o he design
o CDs-based ma e ial such as senso s and d ug nanoca ie s.
3.6. Re e ences
1. Yan, F.; Jiang, Y.; Sun, X.; Bai, Z.; Zhang, Y.; Zhou, X., Su ace modi ica ion
and chemical unc ionaliza ion o ca bon do s: a e iew. Mic ochimica Ac a 2018, 185
(9), 424.
2. Fu, C.; Qian, K.; Fu, A., A ginine-modi ied ca bon do s p obe o li e cell
imaging and sensing by inc easing cellula up ake e iciency. Ma e ials Science and
Enginee ing: C 2017, 76, 350-355.
3. Chai, L.; Zhou, J.; Feng, H.; Tang, C.; Huang, Y.; Qian, Z., Func ionalized
Ca bon Quan um Do s wi h Dopamine o Ty osinase Ac i i y Moni o ing and Inhibi o
Sc eening: In Vi o and In acellula In es iga ion. ACS Applied Ma e ials & In e aces
2015, 7 (42), 23564-23574.

76
4. Zhong, D.; Zhuo, Y.; Feng, Y.; Yang, X., Employing ca bon do s modi ied wi h
ancomycin o assaying G am-posi i e bac e ia like S aphylococcus au eus.
Biosenso s and Bioelec onics 2015, 74, 546-553.
5. K ishna, A. S.; Radhakuma y, C.; An ony, M.; S eeni asan, K., Func ionalized
ca bon do s enable simul aneous bone c ack de ec ion and d ug deposi ion. Jou nal o
Ma e ials Chemis y B 2014, 2 (48), 8626-8632.
6. Zhang, J.; Zhao, X.; Xian, M.; Dong, C.; Shuang, S., Folic acid-conjuga ed
g een luminescen ca bon do s as a nanop obe o iden i ying ola e ecep o -posi i e
cance cells. Talan a 2018, 183, 39-47.
7. Yang, L.; Wang, Z.; Wang, J.; Jiang, W.; Jiang, X.; Bai, Z.; He, Y.; Jiang, J.;
Wang, D.; Yang, L., Doxo ubicin conjuga ed unc ionalizable ca bon do s o nucleus
a ge ed deli e y and enhanced he apeu ic e icacy. Nanoscale 2016, 8 (12), 6801-
6809.
8. Yang, R.; Guo, X.; Jia, L.; Zhang, Y., A luo escen “on-o -on” assay o
selec i e ecogni ion o Cu(II) and glu a hione based on modi ied ca bon nanodo s, and
i s applica ion o cellula imaging. Mic ochimica Ac a 2017, 184 (4), 1143-1150.
9. Chen, J.; Li, Y.; L , K.; Zhong, W.; Wang, H.; Wu, Z.; Yi, P.; Jiang, J., Cyclam-
unc ionalized ca bon do s senso o sensi i e and selec i e de ec ion o coppe (II) ion
and sul ide anion in aqueous media and i s imaging in li e cells. Senso s and Ac ua o s
B: Chemical 2016, 224, 298-306.
10. Luo, M.; Hua, Y.; Liang, Y.; Han, J.; Liu, D.; Zhao, W.; Wang, P., Syn hesis o
no el β-cyclodex in unc ionalized S, N codoped ca bon do s o selec i e de ec ion o
es os e one. Biosenso s and Bioelec onics 2017, 98, 195-201.
11. Mohammadi, S.; Salimi, A.; Hamd-Ghada eh, S.; Fa hi, F.; Soleimani, F., A
FRET immunosenso o sensi i e de ec ion o CA 15-3 umo ma ke in human se um
sample and b eas cance cells using an ibody unc ionalized luminescen ca bon-do s
and AuNPs-dend ime ap ame as dono -accep o pai . Analy ical Biochemis y 2018,
557, 18-26.
12. Sun, Q.; Fang, S.; Fang, Y.; Qian, Z.; Feng, H., Fluo ome ic de ec ion o
choles e ol based on β-cyclodex in unc ionalized ca bon quan um do s ia compe i i e
hos -gues ecogni ion. Talan a 2017, 167, 513-519.
13. Vallan, L.; U iolabei ia, E. P.; Ruipé ez, F.; Ma xain, J. M.; Can on-Vi o ia, R.;
Tagma a chis, N.; Beni o, A. M.; Mase , W. K., Sup amolecula -Enhanced Cha ge
T ans e wi hin En angled Polyamide Chains as he O igin o he Uni e sal Blue
Fluo escence o Polyme Ca bon Do s. Jou nal o he Ame ican Chemical Socie y 2018.
14. Feng, T.; Zhu, S.; Zeng, Q.; Lu, S.; Tao, S.; Liu, J.; Yang, B., Sup amolecula
C oss-Link-Regula ed Emission and Rela ed Applica ions in Polyme Ca bon Do s.
ACS Applied Ma e ials & In e aces 2018, 10 (15), 12262-12277.
77
4. ELECTRONIC INTERACTIONS
IN CDs/MoS2 ELECTROSTATIC
COMPLEX
78
4.1. Abs ac
In his chap e , a s udy on he elec onic in e ac ions be ween ca bon do s (CDs) and
unc ionalized molybdenum disul ide (MoS2) oligolaye s is epo ed. Fo his pu pose, a
solu ion o nega i ely cha ged CDs ob ained om he mic owa e i adia ion o ci ic
acid and e hylenediamine was i a ed wi h ammonium- unc ionalized posi i ely
cha ged MoS2, and he op ical p ope ies o he o ming elec os a ic complex we e
s udied ongoing. E icien luo escence quenching o CDs by MoS2 was obse ed and
a ibu ed o pho oinduced elec on/ene gy ans e as he decay mechanism o he
ansduc ion o he single exci ed s a e o CDs. Finally, he CD/MoS2 complex was
es ed as ca alys owa ds he hyd ogen e olu ion eac ion and ound o be supe io o
ha o indi idual CDs species.
4.2. In oduc ion
MoS2 is a membe o he laye ed- ansi ion me al dichalcogenides (TMDs), a g oup o
which belong also ungs en disul ide (WS2), an alum(IV) sul ide (TaS2), i anium
disul ide (TiS2), ungs en diselenide (WSe2), molybdenum diselenide (MoSe2), and
many o he s.1 These ma e ials consis o pseudo-2D c ys al laye s held oge he by
non-co alen in e ac ions. The numbe o laye s is di ec ly ela ed o he TMDs op ical
and elec onic p ope ies, which he e o e can be ailo ed as a esul o an ex olia ion
p ocess o he bulk ma e ial. Fo example, bulk MoS2 shows semi-conduc ing
p ope ies, ha ing a band gap o 1.3 eV. Depending on he ex olia ion p ocess,
oligolaye ed o monolaye ed MoS2 can be ob ained, and dec easing he numbe o
laye s he band gap inc eases, up o 1.8 eV o he single laye ed ma e ial. Fu he mo e,
he wid h o he band gap is di ec ly ela ed o he op ical p ope ies o he TMDs:
inc easing he bandgap ene gy in MoS2 esul s in changes in pho oconduc i i y,
abso p ion and pho oluminescence. F om bulk o monolaye , MoS2 shows an inc ease o
pho oluminescence quan um yield by a ac o o up o 104.2 Clea ly, he pho oelec onic
esponse o MoS2 can be o g ea in e es o he design o op oelec onic de ices, such
as pho o- ansis o 3, diodes4, chemical senso s5 and LEDs.6 Mo eo e , he di ec
bandgap ene gy is loca ed in he isible ange, allowing he use o MoS2 in sola cells
and ene gy con e sion.7-9 Howe e , jus like many 2D ma e ials, he p ocessing o
MoS2 has some d aw-backs. In ac , he MoS2 single laye s a e ha dly dispe sible and
once in solu ion hey a e no well s abilized by he sol en , hus hey apidly agg ega e
79
and p ecipi i e as a esul o he ene ge ically a o able s acking be ween laye s. To
o e come his p oblem, se e al app oaches, bo h co alen and non-co alen
unc ionaliza ion wi h o ganic molecules, we e explo ed. Fo example, he g oup o
Tagma a chis achie ed he co alen bonding o 1,2-di hiolanes on he edges o
semiconduc ing MoS2 unde mild condi ions.10 In he e, di hiolanes a e eac ing wi h he
MoS2 edges, whe e he eac i e sulphu acancies a e mos ly ound, hus p ese ing he
basal plane op oelec onic p ope ies. Fu he mo e, his me hod allows in oducing
cha ged o ganic g oups, such as ammonium sal s, on he MoS2 laye s, imp o ing on one
side he dispe sibili y in pola sol en s and on he o he side p o iding sui able moie ies
o he acile coupling wi h o he pho oac i e ma e ials ia elec os a ic in e ac ions. In
his way, hyb id sys ems wi h new op oelec onic p ope ies can be easily p epa ed.
In his wo k, he pho ophysical and elec oca aly ic p ope ies o CDs/MoS2 complexes
a e in es iga ed. CDs bea ing ca boxylic acids we e p epa ed by a s anda d mic owa e
i adia ion p o ocol om ci ic acid and e hylenediamine. A e wa ds, he nega i ely
cha ged ca boxyla e o m was ob ained by mild alkaline ea men . In pa allel,
posi i ely cha ged MoS2 monolaye s we e p epa ed in a wo-s eps p ocedu e, in ol ing
i s he co alen unc ionaliza ion o ex olia ed MoS2 wi h 1,2-di hiolane e -bu yl
ca bama e and second i s acidic dep o ec ion yielding he posi i ely cha ged ammonium
sal . Nex , he i a ion o he nega i e CDs wi h he posi i e MoS2 was ollowed by
UV/ is spec oscopy, s eady-s a e and ime- esol ed pho oluminescence spec oscopy,
allowing o sc u inize he in aensemble elec onic in e ac ions be ween he wo species.
Finally, o e po en ials and Ta el slopes we e e alua ed o he assessmen o he
elec oca aly ic ac i i y o CD/MoS2 owa d he hyd ogen e olu ion eac ion (HER).
4.3. Expe imen al sec ion
4.3.1. Ma e ials
Molybdenum disul ide powde (>99%), chlo osul onic acid (99%), ci ic acid
anhyd ous (≥99.5%) and e hylendiamine (99+%) we e used wi hou u he
pu i ica ions. Dialysis ubes wi h molecula weigh cu -o (MWCO) 0.5-1 KDa we e
bough om Spec um Labs.
86
4.3.3.3 Cha ac e iza ion o MoS2-based ma e ials 2 and 3
Figu e 4.6. ATR-IR spec a o 1,2-di hiolane de i a i e 1 ( ed) and MoS2-based ma e ials
2 (black) and 3 (blue).
ATR-IR spec a compa ison o ma e ials 2 and 3 u nish a p oo o he dep o ec ion
s ep ( igu e 4.6). While s e ching ib a ion bands due o C-H uni s a e iden i ied in he
egion 2800-3000 cm-1 o bo h 2 and 3, wo disc e e bands a 1650 and 1710 cm-1 owed
o ca bonyl amide and BOC uni s, espec i ely, a e p esen in he IR spec um o 2, wi h
he la e band being absen in he spec um o 3, hus jus i ying he e ec i e emo al o
BOC.

87
Figu e 4.7. No malized Raman spec a o ex olia ed MoS2 (black) and MoS2-based
ma e ials 2 (g ay) and 3 (blue), ob ained upon 514 nm exci a ion.
Raman spec oscopy e ealed he p esence o he cha ac e is ic A1g and E12g modes
loca ed a 406 and 382 cm-1, espec i ely, in ma e ials 2 and 3 (Figu e 4.7). Mo eo e ,
he A1g and E12g modes we e ound unal e ed as compa ed wi h he ones p esen in
ex olia ed MoS2. Since o ex olia ed MoS2 he calcula ed equency di e ence be ween
A1g and E12g is 24 cm-1, co esponding o he p esence o 3-4 MoS2 laye s in a e age11,
i is easonable o claim ha he same numbe o laye s exis s in 2 and 3. Addi ionally,
no o he Raman bands we e obse ed in he egion 500-1000 cm-1, indica ing he
absence o oxida ion du ing he ex olia ion and unc ionaliza ion p ocess, hence,
p o ing he p ese a ion o he elec onic p ope ies o he semiconduc ing MoS2
poly ype.
88
Figu e 4.8. The mog aphs o MoS2-based ma e ial 3.
The ζ-po en ial alue changed om -24 mV o ex olia ed MoS2 o +2.6 mV o 3,
being consis en wi h he p esence o ammonium unc ionali ies. Mo eo e , Kaise es
e ealed a alue o 50 μmol/g o ee amine uni s in 3. Then, based on TGA analysis,
he 4.5% mass loss obse ed du ing hea ing o 3 in he empe a u e ange 200-500 oC
unde ni ogen a mosphe e, ela e o he decomposi ion o he o ganic pa inco po a ed
on MoS2, is consis en wi h he p esence o one unc ional g oup o e e y 49 uni s o
MoS2 (Figu e 4.8).
Figu e 4.9. SEM images o MoS2-based ma e ial 3.
SEM specimen was p epa ed by d opcas ing a me hanol dispe sion o MoS2 on o he
sample holde and imaged a e he sol en was allowed o slowly e apo a e. Polygonal
o e lapping shee s o MoS2 wi h sizes anging om hund eds o nanome e s o se e al
89
mic ome e s in a andom dis ibu ion we e obse ed (Figu e 4.9). Ampli ica ion o
se e al a eas o he ma e ial e eals semi- anspa en shee s associa ed o ew laye s o
MoS2, wi h egula and linea edges. I should be poin ed ou ha due o he d ying
p ocess o imaging, e-s aking o he MoS2 laye s occu s explaining no only he
obse ed de ia ion om he spec oscopically calcula ed laye size in solu ion, bu also
he di icul y o iden i ying single-laye ed MoS2 in he modi ied ma e ial 3.
4.4. Ti a ion expe imen
Once p epa ed he posi i ely cha ged modi ied MoS2 3 and he nega i ely cha ged CDs-
4, elec os a ic a ac i e in e ac ions be ween he wo species we e exploi ed (Scheme
4.3) o he p epa a ion o CDs/MoS2 complexes.
Scheme 4.3. P epa a ion o he CDs/MoS2 elec os a ic complex.
The expe imen consis s o a se ies o aqueous i a ion assays. In igu e 4.10a a e
shown he abso p ion spec a o CDs- 4 (0.35 mg/ml) o se e al addi ions o 3. These
spec a a e ob ained by sub ac ion o he MoS2 bands, in o de o isola e and easily
moni o he changes occu ing on he CDs abso p ion band. A p og essi e ed-shi o
he abso p ion o CDs– 4 is obse ed, namely om 350 o 355 nm a e he addi ion o
320 μL o 3. Mo eo e , he complex o ma ion be ween he wo species in he g ound
s a e is sugges ed by he p esence o a b oad isosbes ic poin a 310 nm. In e es ingly,
when he neu al MoS2-based de i a i e 2 was employed o he i a ion (Figu e 4.10b)
nei he he ed-shi no he isosbes ic poin o ma ion we e obse ed, p o ing ha
elec os a ic a ac i e o ces no only p omo e he CDs/MoS2 complex o ma ion, bu
also play a ole o he e ec i e elec onic in e ac ion be ween he wo species.
90
Figu e 4.10. UV-Vis abso p ion spec a o CDs– 4 upon inc emen al addi ions o (a)
ammonium modi ied MoS2-based ma e ial 3. Inse : Enla gemen o he 300-320 nm egion
whe e he isosbes ic poin is de eloped, (b) MoS2-based ma e ial 2.
Addi ional in o ma ion on he pho oinduced elec onic in e ac ions be ween MoS2 and
CDs we e ob ained by s eady-s a e and ime- esol ed luo escence spec oscopy
analysis. Upon inc emen al addi ion o ammonium modi ied MoS2-based ma e ial 3, he
CDs emission a 460 nm (λex=370 nm) is p og essi ely quenched (Figu e 4.11a). Also
when he neu al MoS2-based de i a i e 2 is added quenching is obse ed, bu wi h a
much lowe ex en (Figu e 4.11b). Ne e heless S e n-Volme plo s p o ide a use ul
hin o be e unde s anding he quenching mechanism in he wo sys ems. In ac ,
while he in ensi ies a io I0/I (whe e I0 is he emission in ensi y o he CDs- 4 alone and
I upon he addi ion o quenche ) inc eases linea ly wi h he addi ion o MoS2-based
de i a i e 2, he addi ion o he ammonium modi ied MoS2-based ma e ial 3 esul s in a
cu ed S e n-Volme plo , implying he ocu ing o an addi ional quenching
phenomenon. These esul s sugges ha simple collisions a e esul ing in he dynamic
quenching o CDs o he addi ion o bo h MoS2-based ma e ials 2 and 3, bu only in
he case o he la e an addi ional quenching mechanism is ocu ing, which can be
easonably ela ed o he CDs/MoS2 complex o ma ion.
91
Figu e 4.11. Pho oluminescence i a ion assays o CDs– 4 (20 μg/mL) upon inc emen al
addi ions o (a) posi i ely cha ged MoS2-based ma e ial 3, and (b) neu al MoS2-based
ma e ial 2. Measu emen s we e conduc ed in wa e o samples possessing equal
abso bance a he exci a ion wa eleng h o 370 nm.
Figu e 4.12. S e n-Volme plo o CDs 4 I0/I upon inc emen al addi ions o (a) posi i ely
cha ged MoS2-based ma e ial 3, and (b) neu al MoS2-based ma e ial 2.
Nex , based on he ime-co ela ed-single-pho on-coun ing me hod, he luo escence
emission decay p o iles o CDs– 4 we e acqui ed (Figu e 4.13). The analysis o he
decay p o iles a 460 nm (exci a ion a 376 nm) o he single exci ed s a e o CDs– 4
was exclusi ely monoexponen ially i ed wi h a li e ime o 14.0 ns. Addi ion o he
posi i ely cha ged MoS2-based ma e ial 3 o he nega i ely cha ged CDs– 4 esul ed in
biexponen ial i ing, gi ing ise o he iden i ica ion o wo componen s, namely, one
wi h he same li e ime, a ibu ed o non-in e ac ing CDs and a as e new one wi h 3.0

92
ns li e ime, co esponding o he luo escence quenching o he emission in ensi y o he
single exci ed s a e o CDs wi hin he CDs/MoS2 ensembles. In con as , he
luo escence decay emained monoexponen ially i ed upon addi ion o neu al MoS2-
based de i a i e 2, man aining he li e ime o in ac CDs– 4 and hus excluding in he
blank expe imen he occu ence o elec onic in e ac ions, which ins ead a e p o ed o
he elec os a ic complex.
Figu e 4.13. (a) Decay p o iles o CDs– 4 upon inc emen al addi ions o posi i ely cha ged
MoS2-based ma e ial 3 o (b) neu al MoS2-based ma e ial 2.
Finally, he elec oca aly ic ac i i y o CDs/MoS2 owa ds he hyd ogen e olu ion
eac ion (HER) was examined by employing a o a ing disc wo king glassy ca bon
elec ode in a s anda d h ee-elec ode glass cell a a scan a e o 5 mV/sec in 0.5 M
H2SO4. In gene al, MoS2 a e p omising ma e ials o HER, based on he o e po en ial
and Ta el slope alues hey exhibi .12-14 In addi ion, he aqueous solubili y o CDs
oge he wi h he p esence o su ace unc ional g oups con ibu e o d aw hyd a ed
p o ons, hus enhancing p o on adso p ion capaci y.15 Based on he abo e and
conside ing ha hyd ogen binds oo s ongly o S, hence lea ing as p ima y ac i e si e
o MoS2 he Mo edge, he pe o mance o CDs/MoS2 owa ds he HER was p obed by
linea sweep ol amme y. The pola iza ion cu e o CDs/MoS2 along wi h hose o
indi idual CDs– 4 and ba e glassy ca bon elec ode o compa ison a e shown in Figu e
4.14a. Fo a gi en po en ial, he ca hodic cu en inc eased o CDs/MoS2 as compa ed
o ha based on indi idual CDs– 4 and he ba e ca bon glassy elec ode. The e olu ion
o gaseous hyd ogen o CDs/MoS2 was isualized as bubbles appea ing a cu en s as
small as 0.5 mA/cm2, wi h enhanced a e a a ound -0.7 V s RHE. Since he ca hodic
93
cu en densi y is p opo ional o he amoun o hyd ogen e ol ed, he la e esul
highligh s he be e ca aly ic ac i i y o CDs/MoS2 and p ominen hyd ogen e olu ion
beha io exhibi ing an onse o e po en ial nea -0.5 V s RHE, which is lowe han he
indi idual CDs– 4 by a ound 150 mV. The be e elec oca aly ic ac i i y o CDs/MoS2
is mainly a ibu ed o a syne gic e ec due o enhanced cha ge- ans e kine ics owed
o he in ima e con ac be ween he wo species CDs and MoS2 as well as he p esence
o ac i e si es in MoS2. Nex , he linea egions o he Ta el plo s (Figu e 4.14b) we e i
o he Ta el equa ion, η = B log j + a, whe e η is he o e po en ial, j is he cu en
densi y and B is he Ta el slope, o u he cha ac e ize he luen cha ge anspo
e iciency and he e icacy o he elec oca aly ic eac ion. Analysis o he Ta el slope
helps o elucida e he possible HER mechanism and de ine he a e-limi ing s ep. The
Ta el slope o CDs/MoS2 ensemble was ound o be 22 mV/dec, smalle han he one
owed o CDs– 4 by 4 mV/dec. Conside ing ha smalle Ta el slope sugges s ha o he
gene a ion o an equi alen cu en only a lowe o e po en ial is needed o apply, he
elec oca aly ic ac i i y o indi idual CDs– 4 is imp o ed upon ealiza ion o he
CDs/MoS2 ensemble. The la e imp o emen in cha ge anspo is a ibu ed o good
elec ical con ac be ween he wo componen s in he dono -accep o CDs/MoS2
ensemble, in which cha ge- ans e phenomena p e ail. Mo eo e , he small Ta el slope
o CDs/MoS2 mani es s ha he elec ochemical deso p ion o adso bed hyd ogen a oms
on o he modi ied elec ode o gene a e hyd ogen is he a e-limi ing s ep – see
equa ions 2 and 3 below. Based on he widely applied mechanisms o he HER,
ini ially a p o on is adso bed on o he elec ode su ace ia a educ ion p ocess (Volme
adso p ion [Eq. (1)]) ollowed by ei he di ec bonding o he adso bed hyd ogen a om
wi h ano he p o on and elec on ans e om he elec ode su ace (Hey o sky
deso p ion [Eq. (2)]) o ecombina ion o wo hyd ogen a oms adso bed on he elec ode
su ace (Ta el deso p ion [Eq. (3)]).
94
Figu e 4.14. (a) Linea sweep ol ammog ams o he HER o CDs/MoS2 (black),
indi idual CDs– 4 ( ed) and ba e glassy ca bon elec ode (do ed). Inse : enla ged egion
nea he onse . (b) Ta el plo s o CDs/MoS2 (black) and indi idual CDs– 4 ( ed) showing
o e po en ial s cu en densi y.
Volme adso p ion: H+ + e–  H•(ads) Eq. (1)
Hey o sky deso p ion: H•(ads) + H+ + e–  H2 Eq. (2)
Ta el deso p ion: H•(ads) + H•(ads)  H2 Eq. (3)
4.5. Conclusions
In his s udy aqueous s able CDs/MoS2 complexes we e de eloped, p o i ing o he
Coulomb a ac i e o ces o enabling s ong elec onic in e ac ions be ween he
componen s. The o ma ion o he complexes was ollowed by elec onic abso p ion and
pho oluminescence i a ion assays, complemen ed by ime- esol ed luo escence
emission, p o ing in his way he occu ing o he in a-complex elec onic in e ac ion.
Signi ican quenching o he CDs pho oluminescence by MoS2 was e ealed, p omp ing
o an addi ional deac i a ion channel – elec on and/o ene gy ans e – s a ing om
he single exci ed s a e o CDs wi hin he CDs/MoS2 ensembles. Mo eo e , he
elec oca aly ic pe o mance o CDs/MoS2 was e alua ed ega ding he HER and ound
imp o ed in compa ison wi h ha o he indi idual CDs species. Wi hou a doub , such
CDs/MoS2 ensembles pe o ming in elec on dono -accep o schemes can be u he
exploi ed o managing cha ge- ans e p ocesses as well as o elec oca alysis and may
be use ul o ad ancing he ield o ene gy con e sion in a wide ange o echnological
and en i onmen al applica ions.
95
4.6. Re e ences
1. Chhowalla, M.; Shin, H. S.; Eda, G.; Li, L.-J.; Loh, K. P.; Zhang, H., The
chemis y o wo-dimensional laye ed ansi ion me al dichalcogenide nanoshee s.
Na u e Chemis y 2013, 5, 263.
2. Wang, Q. H.; Kalan a -Zadeh, K.; Kis, A.; Coleman, J. N.; S ano, M. S.,
Elec onics and op oelec onics o wo-dimensional ansi ion me al dichalcogenides.
Na u e Nano echnology 2012, 7, 699.
3. Lee, H. S.; Min, S.-W.; Chang, Y.-G.; Pa k, M. K.; Nam, T.; Kim, H.; Kim, J.
H.; Ryu, S.; Im, S., MoS2 Nanoshee Pho o ansis o s wi h Thickness-Modula ed
Op ical Ene gy Gap. Nano Le e s 2012, 12 (7), 3695-3700.
4. Jeong, H.; Bang, S.; Oh, H. M.; Jeong, H. J.; An, S.-J.; Han, G. H.; Kim, H.;
Kim, K. K.; Pa k, J. C.; Lee, Y. H.; Le ondel, G.; Jeong, M. S., Semiconduc o –
Insula o –Semiconduc o Diode Consis ing o Monolaye MoS2, h-BN, and GaN
He e os uc u e. ACS Nano 2015, 9 (10), 10032-10038.
5. Pe kins, F. K.; F iedman, A. L.; Cobas, E.; Campbell, P. M.; Je nigan, G. G.;
Jonke , B. T., Chemical Vapo Sensing wi h Monolaye MoS2. Nano Le e s 2013, 13
(2), 668-673.
6. Ross, J. S.; Klemen , P.; Jones, A. M.; Ghimi e, N. J.; Yan, J.; Mand us, D. G.;
Taniguchi, T.; Wa anabe, K.; Ki amu a, K.; Yao, W.; Cobden, D. H.; Xu, X.,
Elec ically unable exci onic ligh -emi ing diodes based on monolaye WSe2 p–n
junc ions. Na u e Nano echnology 2014, 9, 268.
7. Wang, K.; Wang, J.; Fan, J.; Lo ya, M.; O’Neill, A.; Fox, D.; Feng, Y.; Zhang,
X.; Jiang, B.; Zhao, Q.; Zhang, H.; Coleman, J. N.; Zhang, L.; Blau, W. J., Ul a as
Sa u able Abso p ion o Two-Dimensional MoS2 Nanoshee s. ACS Nano 2013, 7 (10),
9260-9267.
8. Huang, X.; Zeng, Z.; Zhang, H., Me al dichalcogenide nanoshee s: p epa a ion,
p ope ies and applica ions. Chemical Socie y Re iews 2013, 42 (5), 1934-1946.
9. Pume a, M.; So e , Z.; Amb osi, A., Laye ed ansi ion me al dichalcogenides
o elec ochemical ene gy gene a ion and s o age. Jou nal o Ma e ials Chemis y A
2014, 2 (24), 8981-8987.
10. Can on-Vi o ia, R.; Sayed-Ahmad-Ba aza, Y.; Pelaez-Fe nandez, M.; A enal,
R.; Bi encou , C.; Ewels, C. P.; Tagma a chis, N., Func ionaliza ion o MoS2 wi h 1,2-
di hiolanes: owa d dono -accep o nanohyb ids o ene gy con e sion. npj 2D
Ma e ials and Applica ions 2017, 1 (1), 13.
11. Li, H.; Zhang, Q.; Yap, C. C. R.; Tay, B. K.; Edwin, T. H. T.; Oli ie , A.;
Bailla gea , D., F om Bulk o Monolaye MoS2: E olu ion o Raman Sca e ing.
Ad anced Func ional Ma e ials 2012, 22 (7), 1385-1390.
12. Wang, D.; Xiao, Y.; Luo, X.; Wu, Z.; Wang, Y.-J.; Fang, B., Swollen
Ammonia ed MoS2 wi h 1T/2H Hyb id Phases o High-Ra e Elec ochemical Ene gy
S o age. ACS Sus ainable Chemis y & Enginee ing 2017, 5 (3), 2509-2515.
13. Chou, S. S.; Sai, N.; Lu, P.; Coke , E. N.; Liu, S.; A yushko a, K.; Luk, T. S.;
Kaeh , B.; B inke , C. J., Unde s anding ca alysis in a mul iphasic wo-dimensional
ansi ion me al dichalcogenide. Na u e communica ions 2015, 6, 8311-8311.
14. Li, Y.; Wang, H.; Xie, L.; Liang, Y.; Hong, G.; Dai, H., MoS2 Nanopa icles
G own on G aphene: An Ad anced Ca alys o he Hyd ogen E olu ion Reac ion.
Jou nal o he Ame ican Chemical Socie y 2011, 133 (19), 7296-7299.
15. Li, H.; Liu, J.; Guo, S.; Zhang, Y.; Huang, H.; Liu, Y.; Kang, Z., Ca bon do s
om PEG o highly sensi i e de ec ion o le odopa. Jou nal o Ma e ials Chemis y B
2015, 3 (11), 2378-2387.
102
il a e is washed h ee imes wi h E 2O. The excess o bu ylamine is emo ed unde
acuum in a o a y e apo a o . Finally he wa e phase is pu i ied by dialysis in
ul apu e wa e (molecula weigh cu -o = 0.5-1 kDa, 3 days). The d y p oduc CDs
(0.7g), consis ing o a yellow powde , is ob ained by eeze-d ying. Scheme 5.1a.
In he second s ep 200 mg o CDs we e dissol ed in 5 ml o MeOH and 25 ml o
dichlo ome hane (DCM) and cooled in ice-ba h. In ano he lask, 300 mg o lipoic acid
we e dissol ed in 5 ml o DCM, cooled in ice-ba h and 336 mg o (3-
Dime hylaminop opyl)-N′-e hylca bodiimide hyd ochlo ide (EDC) coupling agen we e
added. A e 20 minu es, he lipoic acid solu ion was pou ed o he CDs one. The
eac ion was le o e nigh s i ing and he day a e 100 mg o lipoic acid and 56 mg o
EDC we e added. A e 3h he eac ion was washed one ime wi h wa e , one ime wi h
a NaOH wa e solu ion (pH=11) and one ime wi h b ine. The DCM was pa ially
emo ed by acuum and dilui ed wi h e hyl ace a e, causing he p ecipi a ion o he
pa icles (cen i uga ion a 3200 .p.m., 5 min.). The edispe sion-p ecipi a ion was
epea ed un il he lipoic acid spo in TLC disappea ed. The p ecipi a e was dissol ed
again in MeOH/DCM 1:1 and MgSO4 was added o d y he wa e aces. -CDs, in he
o m o a b own solid, we e ob ained by acuum emo al o he sol en . Scheme 5.1b.
5.3.2.2 CDs cha ac e iza ion
The s uc u e o CDs and -CDs was de e mined by 1H NMR spec oscopy (Figu e 5.1).
All he signals o he as-syn he ized CDs a e ound in he alipha ic egion and
co espond o he me hylene p o ons o ci ic acid and e hylenediamine s uc u al
componen s (4.0-2.3 ppm) and bu yl uni s (1.6-0.7 ppm). Thus, he polyme na u e o
he s uc u e and he occu ing o he bu ylamine unc ionaliza ion we e con i med. In
he modi ied -CDs, mul iple s appea be ween 2.6 and 1.5 ppm, co esponding o he
p o ons o he lipoic amide moie y condensed on o he su ace o he nanopa icles.

103
Figu e 5.1. H1 NMR spec a o CDs (blue) and -CDs ( ed).
The IR ea u es in he as-p oduced CDs (Figu e 5.2) a e assigned as o O-H and N-H
s e ching ib a ions a 3300-3000 cm-1, C-H s e ching a 2920 cm-1, C=O s e ching o
ee ca boxylic acid uni s a 1705 cm-1, C=O s e ching o amide uni s a 1640 and 1630
cm-1, and C-O and C-N s e ching a 1440-1360 cm-1. In he modi ied -CDs, he
in ensi y o he C=O s e ching amide band inc eased.
Figu e 5.2. ATR-IR spec a o as-p oduced CDs (blue) and 1,2-di hiolane modi ied -CDs
( ed).
104
Fu he p oo o he unc ionaliza ion was gi en by he Kaise es , whe e he amoun o
ee amines on CDs dec eased signi ican ly upon condensa ion wi h lipoic acid, om
1810 o 72 µmol/g. The 1,2-di hiolane unc ionaliza ion had an impac on he CDs
op ical p ope ies, esul ing in a ed-shi om 345 o 370 nm o he -CDs abso bance
and om 450 o 470 nm o he -CDs emission (Figu e 5.3).
Figu e 5.3. UV-Vis (le ) and emission ( igh , λex=370 nm) spec a o as-p oduced CDs
(blue) and 1,2-di hiolane modi ied -CDs ( ed), ob ained in me hanol.
5.3.4. P epa a ion o ex olia ed MoS2 and WS2
Bulk TMDs (150-200 mg) we e dispe sed in chlo osul onic acid and sonica ed o 2
hou s a oom empe a u e. The solu ion was le unde s i ing du ing a mon h,
occasionally sonica ed o 30 seconds. A e wa ds cold wa e was added o he solu ion
unde s i ing, d op by d op and ex emely ca e ully. Please no ice ha he eac ion is
exo he mic and eleases gaseous HCl. Nex , he mix u e was il a ed on a PTFE il e
o 0.2 μm po e-size and washed wi h a good amoun o me hanol and ace one. The solid
compound was added o N-me hyl py olidone and sonica ed o 1 hou ( ip sonica ion
a 30-35% o ampli ude (100% o 200 W)). A e 3 days he supe na an was aken,
il a ed on PTFE il e (0.2 μm po e-size) and washed wi h a la ge amoun o me hanol,
ace one and dichlo ome hane.
5.4. Resul s and discussion
The -CDs we e conjuga ed o MoS2 and WS2 ollowing he he unc ionaliza ion
me hodology o TMDs wi h 1,2-di hiolanes.39-41 In he e, he -CDs (50 mg) we e
dissol ed in me hanol (1 mL). In ano he lask, ex olia ed TMDs (20 mg) we e
105
dispe sed in DMF (10 mL) by sonica ion (10 min) and d opped in he CNDs solu ion.
The lask was co e ed wi h aluminum oil and he eac ion mix u e was s i ed a 70 °C
o 4 days. A e ha pe iod, i was cooled and il e ed h ough a PTFE memb ane (0.2
nm po e size). The solid esidue was ex ensi ely washed wi h me hanol and
dichlo ome hane o ob ain he CD-TMDs (Scheme 5.2).
Scheme 5.2. Illus a i e p epa a ion o CD-MoS2 and CD-WS2 upon co alen 1,2-
di hiolane unc ionaliza ion o ex olia ed semiconduc ing MoS2 and WS2 nanoshee s.
The as ob ained CD-MoS2 and CD-WS2 hyb ids we e u he ly cha ac e ized by IR and
Raman spec oscopy, he mog a ime ic analysis (TGA) and ansmission elec on
mic oscopy (TEM). In he ATR-IR spec a o CD-MoS2 and CD-WS2 (Figu e 5.4), he
p esence o CDs was e ealed by he bands a 1640 and 1550 cm-1, co esponding o he
amide C=O s e ching and N-H bending modes, as well as by he sha p bands a 300-
2800 cm cm-1, due o he C-H s e ching.
106
Figu e 5.4. ATR-IR spec a o o CD-MoS2 (black) and CD-WS2 (g ey).
Raman spec oscopy is a use ul echnique o p o ing he ocu ence o he co alen
unc ionaliza ion. The spec a o ex olia ed MoS2 and WS2 we e compa ed wi h he ones
o he espec i e CD-MoS2 and CD-WS2 hyb ids, ob ained upon exci a ion unde on-
esonance condi ions a 633 nm and no malized a he A1g mode a 404 cm-1 (Figu e
5.5). In his way, i was ound ha he in ensi y o he 2LA(M) band o MoS2, loca ed a
447 cm-1 and associa ed o diso de and de ec s,9 dec eased a e he unc ionaliza ion o
MoS2 wi h -CDs, as a consequence o he educed numbe o S de ec s (Figu e 5.5a).
Mo eo e , he absence o he cha ac e is ic phonon modes o me allic poly ype MoS2
so-called J1, J2 and J3 a 150, 225 and 325 cm-1, espec i ely,10-11 asce ained he
semiconduc ing beha io o MoS2 in he CD-MoS2 hyb id ma e ial. Rega ding CD-
WS2, bands due o 2LA(M), E12g, and A1g, upon on- esonance exci a ion a 514 nm,
we e ound a 350, 354 and 419 cm-1, wi h he in ensi y o he 2LA(M) mode dec eased
by 20% as compa ed o ex olia ed WS2 (Figu e 5.5b). Fu he mo e, o bo h CD-MoS2
and CD-WS2, he A1g and E12g modes ed-shi ed by 1-2 cm-1 as compa ed o he alues
egis e ed o ex olia ed MoS2 and WS2, espec i ely. The la e is a ibu ed o
in ahyb id cha ge- ans e phenomena de eloped be ween -CDs and he TMDs, in
acco dance wi h li e a u e epo s.12-13
107
Figu e 5.5. Raman spec a no malized a A1g mode o (a) ex olia ed MoS2 (blue) and CD-
MoS2 (black) a λexc 633 nm, and (b) ex olia ed WS2 (blue) and CD-WS2 (g ey) a λexc 514
nm.
Since CDs a e highly luo escen , weak and b oad Raman bands a ibu ed o –NC=O,
C=O and C-H uni s (1700-1200 cm-1 and 700-500 cm-1) we e obse ed o bo h CD-
MoS2 and CD-WS2 only upon exci a ion a 1064 nm (Figu e 5.6).
Figu e 5.6. Raman spec a (1064 nm) o CDs ( ed), CD-MoS2 (black) and CD-WS2 (g ey).
TGA was employed o e alua ing he loading o CDs conjuga ed on o MoS2 and WS2
in CD-MoS2 and CD-WS2. When hea ed unde ni ogen a mosphe e, -CDs los he
65% o mass be o e eaching 500ºC (Figu e 5.7). Since MoS2 and WS2 a e he mally
s able in ha empe a u e ange, he obse ed mass loss a 500 ºC o CD-MoS2 and
CD-WS2, 7.5% and 3.0% espec i ely, is ela ed o he decomposi ion o -CDs p esen

108
in he wo hyb ids. I should be no iced ha ungs en a oms a e a ound wo imes
hea ie han molybdenum a oms, hus, o an equi alen load o CDs, he WS2 weigh
pe cen age in CD-WS2 is conside ably g ea e han he MoS2 weigh pe cen age in CD-
MoS2. Taking his in o accoun , he unc ionaliza ion a es esul simila in he wo
hyb ids. Mo eo e , al hough his is a ela i ely small mass loss, i is consis en wi h he
edge unc ionaliza ion o he limi ed S acan si es o MoS2 and WS2.3
Figu e 5.7. The mog aphs o CDs ( ed), ex olia ed MoS2 (do ed black), ex olia ed WS2
(do ed g ay), CD-MoS2 (black), and CD-WS2 (g ey).
The mo phology o CD-MoS2 and CD-WS2 hyb ids we e imaged by HR-TEM. A ew
d ops o a dispe sion o he ma e ials in hexane we e deposi ed on he TEM g id and
imaged a e he sol en was e apo a ed. Ex ensi e imaging o se e al di e en a eas
and lakes o he CD-MoS2 and CD-WS2 hyb id ma e ials e ealed ha he size o MoS2
and WS2 is in he o de o ew hund ed nanome es, e.g. a ound 200-400 nm (Figu e
5.8).
109
Figu e 5.8. Rep esen a i e low-magni ica ion HR-STEM-ADF images o CD-MoS2 (le )
and CD-WS2 ( igh ).
Al hough mos ly oligolaye ed lakes we e obse ed, mos likely due o es acking o he
TMDs du ing he d ying p ocess o he sample a e deposi ing i on he TEM g id, he
p esence o some monolaye ed ones we e also iden i ied. In o de o ge be e insigh
on CD-MoS2 and CD-WS2, TEM s udies complemen ed wi h spa ially- esol ed elec on
ene gy loss spec oscopy (EELS) we e pe o med. Figu es 5.9a and 5.10a show high
angle annula da k ield (HAADF) scanning TEM (STEM) mic og aphs o CD-MoS2
and CD-WS2, espec i ely. Based on he ollowing spec oscopic/chemical TEM
analyses, he b igh small objec s obse ed in hese images was assigned o -CDs
co alen ly ancho ed on TMD lakes. This is con i med by ene gy dispe si e X- ay
spec oscopy (EDS) analyses (Figu es 5.9b and 5.10b) and EELS (Figu es 5.9c-e and
5.10c-e). Figu e 5.9c displays an ADF mic og aph o CD-MoS2 and an EELS spec um-
image (SPIM) was eco ded in he ed ma ked ec angula a ea. Th ee EEL spec a we e
ex ac ed in he highligh ed squa e egions (Figu e 5.9e(i)-(iii)). Each o hese h ee
EEL spec a co esponds o he sum o 9 spec a (3x3 p obe posi ions o he SPIM). The
S-L2,3 and Mo-M edges a e isible in he h ee spec a and co espond o MoS2.14-15 I is
wo h men ioning ha no MoOx was obse ed highligh ing he high quali y and pu i y
o he ma e ials. In addi ion, C was de ec ed in speci ic a eas, see he p esence o he C-
K edge (Figu e 5.9e(ii)-(iii)). This C-K edge, which is supe posed o he Mo-M4,5 edge,
is associa ed wi h he p esence o CDs wi hin he CD-MoS2 hyb id. The chemical C
map ob ained om he analysis o C-K edge (Figu e 5.9d) clea ly suppo s his
inding.14-15 Indeed, -CDs a e obse ed no only in he ADF-STEM mic og aph (Figu e
5.9c) bu also in his C-map (Figu e 5.9d). Simila assays we e pe o med o CD-WS2
and om TEM analyses (Figu es 5.10a-e) he p esence o -CDs a ached on WS2 was
con i med.
110
Figu e 5.9. Rep esen a i e HRSTEM-ADF images o (a, d) CD-MoS2. (b) EDS acqui ed
on he squa ed whi e a ea in (a). In he ed egions o (c) spec a images o SR-EELS we e
eco ded. (d) Ca bon elemen al map ex ac ed om he in eg a ed in ensi y o he C-K
edge o he EELS spec um image eco ded in he ed a ea in (c). (e) Th ee spec a om
he sum o nine (3 × 3) EEL spec a ex ac ed om he ma ked a eas o he EELS SPIM
o (c). The C-K edge (∼284 eV) is obse ed in (ii) and (iii) supe posed wi h he Mo-M edge.
The S-L2,3 and Mo-M edge o MoS2 a e isible in he h ee spec a ((i)−(iii)).
111
Figu e 5.10. Rep esen a i e HRSTEM-ADF images o (a, d) CD-WS2. (b) EDS acqui ed
on he squa ed whi e a ea in (a). In he ed egions o (c) spec a images o SR-EELS we e
eco ded. (d) Ca bon elemen al maps ex ac ed om he in eg a ed in ensi y o he C-K
edge o he wo EELS spec a image eco ded in he ed a ea in (c). (e) Th ee spec a om
he sum o 16 (4 × 4) EEL spec a ex ac ed om he EELS SPIM o (c), showing he S-
L2,3 and C-K (in his case only in (ii) and (iii)) edges. The C-K edge (∼284 eV) is obse ed
in (ii) and (iii). The S-L2,3 edge is isible in he h ee spec a ((i)−(iii)).
The CD-MoS2 and CD-WS2 we e analyzed by elec onic abso p ion and luo escence
spec oscopy. The UV-Vis spec a o CD-MoS2 and CD-WS2 (Figu e 5.11) con i med
he p ese a ion o he semiconduc ing monolaye ed o m, cha ac e ized by he bands
cen e ed a 680, 620, 485, 400 nm, and 645, 535, 475, 420 nm, o MoS2 and WS2
espec i ely, in addi ion o con inuous abso p ion h oughou he isible egion due o
he p esence o bo h TMDs and -CDs (Figu e 5.11a). Un o una ely, he s ong
abso p ion ea u es o TMDs masked he b oad band o -CDs, appea ing a 370 nm
(Figu e 5.3a), hus impeeding o in es iga e he elec onic in e ac ion be ween he wo
ma e ials in he g ound s a e. Ne e heless, clea changes a e obse ed in he exci ed
s a e, whe e he s ong emission o -CDs, cen ed a 470 nm upon exci a ion a 370 nm,
231
9.3.21. UV/ is spec a o CDs 3a-e
Figu e 9.104. UV/ is spec a o CDs 3a-e.

232
9.3.22. Exci a ion and emission spec a o CDs 3a-e
CDs 3a
Figu e 9.105. (le ) exci a ion spec a o di e en emissions and ( igh ) emission spec a
o di e en exci a ions o CDs 3a.
CDs 3b
Figu e 9.106. (le ) exci a ion spec a o di e en emissions and ( igh ) emission spec a
o di e en exci a ions o CDs 3b.
233
CDs 3c
Figu e 9.107. (le ) exci a ion spec a o di e en emissions and ( igh ) emission spec a
o di e en exci a ions o CDs 3c.
CDs 3d
Figu e 9.108. (le ) exci a ion spec a o di e en emissions and ( igh ) emission spec a
o di e en exci a ions o CDs 3d.
234
CDs 3e
Figu e 9.109. (le ) exci a ion spec a o di e en emissions and ( igh ) emission spec a
o di e en exci a ions o CDs 3e.
235
9.3.23. Fi ing o he QY calcula ion o CDs 3a-e
Figu e 9.110. abso bance s in eg a ed luo escence in ensi y o CDs 3a-e a di e en
concen a ions. The slope o he linea i ing was used o calcula ing he QY.
236
10. ANNEX D

237
10.1. Abs ac
In his s udy, sodium bo ohyd ide (NaBH4) eac i i y was es ed owa ds he CD-MoS2 hyb id
p epa ed in Chap e 5. The addi ion o NaBH4 o a CD-MoS2 dispe sion was e lec ed in he
clea age o he hiol-molybdenum bond be ween CDs and MoS2 and he e o e in he loss o
he co alen unc ionaliza ion.
10.2. Expe imen al sec ion
Fo he p epa a ion o he hyb id CD-MoS2 see chap e 5.
10.3. Resul s and discussion
A e dispe sing 10 mg o CD-MoS2 in DMF by sonica ion, a cen i uga ion (5000 .p.m., 5
minu es) was pe o med in o de o p ecipi a e he ma e ial and he supe na an was collec ed.
As expec ed, no ace o CDs was de ec ed in he supe na an by UV/ is o PL spec oscopy,
being CDs i mly a ached on o MoS2 by co alen bond. The e o e, he same ma e ial was
edispe sed in DMF and his ime ew millig ams o NaBH4 we e added. The abso p ion
(Figu e 10.1a) and luo escence emission (Figu e 10.1b) o he dispe sion we e measu ed
be o e and a e he NaBH4 addi ion. In e es ingly, a e he addi ion, he emission in ensi y o
he CDs inc eased conside ably, sugges ing ha he co alen bond wi h MoS2 was b oken and
he luo escence was no a ec ed anymo e by i s quenching e ec . In o de o con i m his
hypo hesis, a e he addi ion o NaBH4 he dispe sion was cen i uged as done p e iously and
he supe na an was sepa a ed om he p ecipi a e, which was il e ed and washed wi h DMF
and wa e . The IR p o ile o he d y p ecipi a e does no p esen anymo e he cha ac e is ic
bands o he CDs be ween 1700-1600 cm-1 belonging o C=O s e ching ( igu e 1.10c). On he
con a y he UV/ is spec um o he supe na an clea ly shows he abso p ion p o ile o he
CDs ( igu e 1.10d). These e idences u he highligh he key ole o he s able co alen bond
in he occu ence o he elec onic in e ac ion be ween CDs and MoS2. Addi ionally, i is
shown ha a s ong educing agen as NaBH4 is able o b eak he hiol-molybdenum bond.
238
Figu e 10.1. UV/Vis spec a o he CD-MoS2 dispe sion be o e (black) and a e ( ed)
NaBH4 addi ion, (b) luo escence emission spec a (λexc 370 nm) o he CD-MoS2
dispe sion be o e (black) and a e ( ed) NaBH4 addi ion, (c) IR spec a o he d y
p ecipi a e ob ained by cen i uga ion be o e (black) and a e ( ed) NaBH4 addi ion, (d)
UV/Vis spec a o he supe na an ob ained by cen i uga ion be o e (black) and a e
( ed) NaBH4 addi ion.
239
11. ANNEX E
240
11.1. Abs ac
In his s udy, he syn hesis o luo escen CDs is accomplished by mic owa e i adia ion o a
solid mix u e o ci ic acid and u ea. Fil a ion and dialysis allowed o sepa a e he aw
ma e ial by size, ob aining ou di e en ac ions. The s uc u al cha ac e iza ion o he
ac ions was pe o med by in a ed spec oscopy and elemen al analysis, u nishing
in e es ing in o ma ion o he unde s anding o he nanopa icles g ow h p ocess.
Addi ionally, di e ences in he op ical beha io we e poin ed ou by abso p ion spec oscopy
and s eady s a e luo escence spec oscopy cha ac e iza ion. Finally, he ull da ase was
in e p e ed unde he ligh o he indings epo ed in Chap e 2.
11.2. Expe imen al pa
11.2.1. Ma e ials
Ci ic acid monohyd a e (99.5%) and u ea (99%) we e used wi hou u he pu i ica ions.
Dialysis ubes wi h molecula weigh cu -o (MWCO) 0.5-1 KDa we e bough om
Spec um Labs.
11.2.2. Cha ac e iza ion echniques
 The mic owa e-assis ed eac ion was pe o med in a CEM Disco e SP eac o
employed in a closed essel.
 Elemen al analyses we e pe o med in a The mo Flash EA 1112 ins umen wi h ∼3
mg o powde samples.
 In a ed abso p ion measu emen s we e pe o med on powde samples p essed wi h
KB in o pelle s wi h a B uke Ve ex 70 spec ome e .
 UV/Vis abso p ion spec a we e eco ded on a Shimadzu UV-2401 PC
spec opho ome e .
 Pho oluminescence exci a ion and emission spec a we e eco ded on a Ho iba Jobin
Y on Fluo omax-P, sli s o exci a ion and emission a 1 mm. All he spec a we e
eco ded a oom empe a u e using 10 mm pa h-leng h qua z cu e e.
247
LIST OF SCIENTIFIC
CONTRIBUTIONS

248
Publica ion 1: Sup amolecula -enhanced cha ge- ans e wi hin en angled polyamide chains
as o igin o he uni e sal blue luo escence o polyme ca bon do s
Lo enzo Vallan, Es eban P. U iolabei ia, Fe nando Ruipé ez, Jon Ma in Ma xain, Ruben
Can on-Vi o ia, Nikos Tagma a chis, Ana M. Beni o, Wol gang K. Mase
Jou nal o he Ame ican Chemical Socie y 2018, 140 (40), 12862-12869.
Con ibu ion: expe imen al pa (syn hesis, mos o he cha ac e iza ion), p epa a ion o he
manusc ip .
Publica ion 2: Elec onic In e ac ions in Illumina ed Ca bon Do /MoS2 Ensembles and
Elec oca aly ic Ac i i y owa ds Hyd ogen E olu ion
Ruben Can on-Vi o ia, Lo enzo Vallan, Es eban U iolabei ia, Ana M. Beni o,Wol gang K.
Mase ,and Nikos Tagma a chis
Chemis y – A Eu opean Jou nal 2018, 24 (41), 10468-10474.
Con ibu ion: expe imen al pa (syn hesis, mos o he cha ac e iza ion) and he i s a icle
d a . Equal con ibu ion o i s and second au ho .
Publica ion 3: In e acing ansi ion me al dichalcogenides wi h ca bon nanodo s o
managing pho oinduced ene gy and cha ge- ans e p ocesses
Lo enzo Vallan, Ruben Can on-Vi o ia, Hab om B. Gobeze, Youngwoo Jang, Raul A enal,
Ana M. Beni o, Wol gang K. Mase , F ancis D’ Souza, Nikos Tagma a chis
Jou nal o he Ame ican Chemical Socie y 2018, 140 (41), 13488-13496.
Con ibu ion: expe imen al pa (syn hesis, pa o he cha ac e iza ion) and he i s a icle
d a . Equal con ibu ion o i s , second and hi d au ho .
Publica ion 4: A e sa ile me hod o he con ollable oom- empe a u e syn hesis and in-si u
unc ionaliza ion o luo escen ca bon do s (submi ed o Angewand e Chemie In e na ional
Edi ion)
Lo enzo Vallan, Es eban P. U iolabei ia, Ana M. Beni o, Wol gang K. Mase
Con ibu ion: Syn hesis and cha ac e iza ion o he ma e ials (excep NMR cha ac e iza ion),
p epa a ion o he manusc ip .