New heteroleptic Zn(II) complexes of thiosemicarbazone and diimine Co-Ligands: Structural analysis and their biological impacts

Publication date: 5 February 2018
Source:Journal of Molecular Structure, Volume 1153
Author(s): Shanmugaiah Mathan Kumar, Mookkandi Palsamy Kesavan, Gujuluva Gangatharan Vinoth Kumar, Murugesan Sankarganesh, Ganesan Chakkaravarthi, Gurusamy Rajagopal, Jegathalaprathaban Rajesh
A thiosemicarbazone ligand HL appended new Zn(II) complexes [Zn(L)(bpy)] (1) and [Zn(L)(phen)] (2) (where, HL = {2-(3-bromo-5-chloro-2-hydroxybenzylidene)-N-phenylhydrazinecarbothioamide}, bpy = 2, 2′-bipyridine and phen = 1, 10-phenanthroline) have been synthesized and well characterized using conventional spectroscopic techniques viz.,¹H NMR, FTIR and UV–Vis spectra. The crystal structures of complexes 1 and 2 have been determined by single crystal X-ray diffraction studies. Both the complex 1 (τ = 0.5) and 2 (τ = 0.37) possesses square based pyramidally distorted trigonal bipyramidal geometry. The ground state electronic structures of complexes 1 and 2 were investigated by DFT/B3LYP theoretical analysis using 6-311G (d,p) and LANL2DZ basis set level. The superior DNA binding ability of complex 2 has been evaluated using absorption and fluorescence spectral titration studies. Antimicrobial evaluation reveals that complex 2 endowed better screening than HL and complex 1 against both bacterial as well as fungal species. Consequently, complex 2 possesses highest antibacterial screening against Staphylococcus aureus (MIC = 3.0 ± 0.23 mM) and antifungal screening against Candida albicans (MIC = 6.0 ± 0.11 mM). Furthermore, the anticancer activity of the ligand HL, complexes 1 and 2 have been examined against the MCF-7 cell line (Human breast cancer cell line) using MTT assay. It is remarkable that complex 2 (12 ± 0.67 μM) show highest anticancer activity than HL (25.0 ± 0.91 μM) and complex 1 (15 ± 0.88 μM) due to the presence of phen ligand moiety.

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