Synthesis, spectral characterization, antimicrobial evaluation and molecular docking studies of new Cu (II), Zn (II) thiosemicarbazone based on sulfonyl isatin

Reaction of 5-(morpholinisulfonyl)isatin (1) with thiosemicarbazide derivative appended the corresponding thiosemicarbazone derivative 3 that further coordinated with copper and zinc acetate to afford copper and zinc complexes 4 and 5 , respectively. The structure of the ligand and its two complexes Cu (II) and Zn (II) are confirmed using elemental analysis, molar conductance, spectra data (FT-IR, 1 H NMR, 13 C NMR, mass spectra), and thermogravimetric analysis (TGA). The ligand bounds to metal complex as neutral tridentate (ONS) donor with tetrahedral geometry structure. Additionally, the ligand forms two five-member rings with metals via carbonyl of isatin derivative, the nitrogen of azomethane (C = N), and sulpher of thiosemicarbazone. The antimicrobial activity was evaluated against two Gram-positive, two Gram-negative bacteria, and one fungal strain. Both complexes revealed antimicrobial activity against the tested strains. In addition, the result exhibited that the zinc complex 5 displayed higher activity than copper complex 4 , where the zinc complex 5 showed an inhibition zone between (18 +/- 0.20 and 23 +/- 0.31) mm and activity index ranged between (84 and 100%) compared with Tetracycline. Moreover, the zinc complex 5 exhibited MIC (24.59-98.42 mu M) in comparison to Tetracycline (35.14-140.62 mu M). Finally, the in silico molecular docking study for thiosemicarbazone derivatives 3 , 4 , and 5 were carried out inside five acti ve sites as an antibacterial targets. Among them, the ligand and its metal complexes showed the lower binding affinity and suggested that these derivatives 3 , 4 , and 5 may possibly be DHFR and topoisomerase IV inhibitors.