HIRSHFELD SURFACE ANALYSIS OF THE CRYSTAL STRUCTURE OF THE COMPLEX COMPOUND OF Cu (II) NITRATE BASED ON THE 2,5-DI (METHYLTHIO) -1,3,4-THIADIAZOLE LIGAND

322 Volume 5, Issue 10: Special Issue (EJAR) ISSN: 2181-2020 MPHAPP THE 6TH INTERNATIONAL SCIENTIFIC AND PRACTICAL CONFERENCE “MODERN PHARMACEUTICS: ACTUAL PROBLEMS AND PROSPECTS” TASHKENT, OCTOBER 17, 2025 in-academy.uz HIRSHFELD SURFACE ANALYSIS OF THE CRYSTAL STRUCTURE OF THE COMPLEX COMPOUND OF Cu (II) NITRATE BASED ON THE 2,5-DI (METHYLTHIO) -1,3,4-THIADIAZOLE LIGAND Uzakbergenova G.P. Dauletbaeva D. Torambetov B.S. Kadirova Sh.A. National University of Uzbekistan, Tashkent city, Republic of Uzbekistan e-mail: [email protected] https://doi.org/10.5281/zenodo.17336913 Relevance: Currently, the Hirshfeld surface analysis method is widely used to identify intermolecular interactions in the crystal structure of compounds and to study their impact on the stability of the crystal lattice. The theoretical data obtained through this method are yielding good results in studying the practical properties of crystals. Therefore, investigating the structure of this complex using this method is one of the urgent scientific issues of the research. Research objective: To quantitatively and qualitatively determine the molecular interactions of the copper nitrate complex [CuL2(NO3)2] formed with the ligand 2,5-di (methylthio) -1,3,4thiadiazole (L) using Hirshfeld surface analysis of its crystal structure. Methods and techniques: Hirshfeld surface analysis was conducted using the Crystal Explorer 17.5 program to visualize the intermolecular interactions in the crystal structure. Two-dimensional fingerprint plots were calculated as part of this analysis. On the Hirshfeld surface, points with low impact are colored blue, while colors ranging from green to red indicate points with high impact. For the [CuL2 (NO3) 2] molecule, the Hirshfeld surface dnorm was calculated using standard high surface precision (Figure 1). Figure 1. (a) Hirschfeld surface of the [CuL2(NO3) 2] complex according to dnorm and (b) twodimensional fingerprint areas indicating the percentage contributions of all interactions. According to the results of the analysis of two-dimensional fingerprint region drawings, it was established that the interactions O∙∙∙H/H∙∙∙O (31.4%), S∙∙∙H/N∙∙∙S (19.7%), H∙∙∙H (11%), make the largest contribution to the Hirschfeld surface. Result: The largest share of the total surface L is represented on the fingerprint map as edged wings with 31.4% share of total interactions of O∙∙∙H/H∙∙∙O interactions formed as a result of the interaction of hydrogen atoms in the methyl group with oxygen atoms of neighboring molecules. The greatest contribution of the influence of O∙∙∙H/H∙∙∙O on the Hirschfeld surface is explained by the abundance of intermolecular and intramolecular hydrogen bonds. Also, the contribution of the effects S∙∙∙O/ O...S (3.9%) and N∙∙∙H/H∙∙∙N (3.5%) shows a smaller share (Fig2). 323 Volume 5, Issue 10: Special Issue (EJAR) ISSN: 2181-2020 MPHAPP THE 6TH INTERNATIONAL SCIENTIFIC AND PRACTICAL CONFERENCE “MODERN PHARMACEUTICS: ACTUAL PROBLEMS AND PROSPECTS” TASHKENT, OCTOBER 17, 2025 in-academy.uz Figure 2. The interaction distances of individual atoms in the crystal structure of the [CuL2 (NO3) 2] complex (two-dimensional fingerprint areas and their relative ratio at the Hirschfeld surface) were studied. Conclusion: It was found that the area of fingerprints in the [CuL2(NO3)2] complex has the highest interactions O∙∙∙H/H∙∙∙O (31.4%). This affects the stability of the crystalline arrangement of the molecular structure.