New 1,3,4-thiadiazole compounds including pyrazine moiety: Synthesis, structural properties and antimicrobial features

In the study, some new 1,3,4-thiadiazole compounds were synthesized and we have reported identification of the structures by using UV-Vis, FT-IR, H-1 NMR, C-13 NMR and Mass spectroscopic methods. Antimicrobial activities of the compounds against three microorganisms, namely, Candida albicans ATCC 26555, Staphylococcus aureus ATCC 9144, and Escherichia coli ATCC 25922 were investigated by using disk diffusion method. These thiadiazoles exhibited an antimicrobial activity against Staphylococcus aureus and Candida albicans. The experimental data was supported by the quantum chemical calculations. Density functional theory (DFT) calculations were carried out to obtain the ground state optimized geometries of the molecules using the B3LYP, M06 and PBEIPBE methods with 3-21 g, 4-31 g, 6-311++g(2d,2p), cc-pvtz and cc-pvqz basis sets in the different combinations. Frontier molecular orbitals (FMOs) energies, band gap energies and some chemical reactivity parameters were calculated by using the aforementioned methods and basis sets, and the results were also compared with the experimental UV-Vis data. (C) 2017 Elsevier B.V. All rights reserved.