Synthesis and characterization of a new zinc(II) complex with tetradentate azo-thioether ligand: X-ray structure, DNA binding study and DFT calculation

Abstract

A new zinc(II) complex, [Zn(L)(H2O)](ClO4) (1) with azo-thioether containing NSNO donor ligand, 3-(2-(2-((pyridin-2-ylmethyl)thio)phenyl)hydrazono)pentane-2,4-dione (HL) is synthesized and characterized by several spectroscopic techniques. The distorted square based pyramidal (DSBP) geometry is confirmed by single crystal X-ray structure. The ability of the complex to bind with CT DNA is investigated by UV–vis method and the binding constant is found to be 4.16 × 104 M−1. Competitive binding study with ethidium bromide (EB) by fluorescence method suggests that the zinc(II) complex efficiently displaces EB from EB-DNA. The Stern-Volmer dynamic quenching constant, Ksv is found to be 1.2 × 104 M−1. Theoretical calculations by DFT and TDDFT/CPCM methods are used to interpret the electronic structure and UV–vis spectrum of the complex.