Study of Synthesis, Spectroscopic Characterization and Their Antidiabetic Activity of Some Water Soluble Zn(II) Complexes with N,S-donor Ligands Derived from (E)-N-(Thiophen-2-ylmethylene)anilines

Five new Zinc (II) nitrate complexes of composition [ZnX2L1-3] (where X = Cl−, NO3 − ; Ln = (E)-N- (thiophen-2-ylmethylene) anilines (1–5)) were synthesized. The complexes were characterized by elemental analysis, UV-visible, fluorescence, IR and 1H NMR spectroscopy. Efforts for getting single crystal suitable for X-ray crystal structure could not be achieved. However, from spectroscopic data, the complexes were proposed to adopt four co-ordinated tetrahedral and six co-ordinated octahedral geometry. All complexes were obtained in moderate to good yields and these compounds behave as non-electrolytes in acetonitrile solution. UV-Visible and fluorescence spectral study of complexes 1-5 indicated (intra-ligand) ligand to ligand charge transfer transition. The complexes were screened for their anti-diabetic activity against α-glucosidase enzyme and compared with standard drug acarbose. Inhibition concentration (IC50) of enzyme activity was calculated by systematic enzyme assay. Appropriate controls were used for samples and analysis was performed in triplicate. The Study of the complexes suggested to have four and six coordinate geometry around Zinc atom. Complexes 1-3 were four coordinated tetrahedral structures while complexes 4 and 5 were six coordinated octahedral structures. Compound 1 was found to exhibit effective anti-diabetic activity among the tested compounds.