New Rh(III) chloro complex of a tetradentate S-picolyl azo ligand of acetyl acetone: Synthesis, X-ray structure, spectral characterization, electrochemistry, DFT computation and interaction with DNA

Abstract

A new rhodium(III) complex with thioether containing NSNO donor azo-ligand (HL) is synthesized and characterized by several spectroscopic techniques. The distorted octahedral geometry of the complex was confirmed by single crystal X-ray diffraction. Cyclic voltamogram exhibits quasi-reversible Rh(III)/Rh(IV) oxidation along with ligand based azo bond reduction in acetonitrile. Electronic structure, electrochemical and absorption properties of the complex were interpreted by DFT and TDDFT calculations. The ability of the rhodium(III) complex to bind with CT DNA was investigated by UV–vis method and the binding constant was found to be 7.70 × 104 M−1. Competitive binding study with ethidium bromide (EB) by fluorescence method suggests that the Rh(III) complex efficiently displaces EB from EB-DNA. The Calculated Stern-Volmer dynamic quenching constant, Ksv is 2.07 × 104 M−1.