Synthesis, Spectral Studies and Antimicrobial Activity of Zinc(II) Azide Complexes with N,N-Donor and N,N,S-Donor Schiff Base Ligands Derived from 2-Pyridinecarboxaldehyde

Abstract

Two water soluble Zn(II) Schiff base complexes of composition [Zn(L1)3][Zn(N3)4] (1) and [Zn(L2)2][Zn(N3)4] (2) were synthesized using bidentate N,N-donor (L1) and tridentate N,N,S-donor (L2) of Schiff base ligands viz. (E)-1-phenyl-N-(pyridin-2-ylmethylene)methanamine (L1) and (E)-2-((pyridin-2-ylmethylene)amino)benzenethiol (L2). Different spectroscopic tools such as FT-IR, UV-Vis, 1H NMR and fluorescence spectroscopy have been employed to characterize complexes 1 and 2. Efforts for getting single crystals suitable for X-ray crystal structure could not be achieved. However, from the spectroscopic data and on the basis of the structures of the related zinc(II) complexes reported earlier in the literature, the complexes could be proposed to adopt six coordinated octahedral geometries in one zinc centre coordinated to the ligands and while the other zinc centre has four azides (N3) terminally coordinated resulting in the octahedral and tetrahedral metal geometries around zinc metal atoms. The compounds behave as electrolytes in acetonitrile solution. In vitro antimicrobial activity of the Zn(II) complexes were studied against some microbes like Aspergillus niger, Fusarium ventricossum and Fusarium chlamydosporum. Effective antifungal activity of complex 2 was found against the tested fungal strains.