Synthesis, characterization and biological evaluation of piperazine embedded copper complexes

Abstract

In this paper, we report the synthesis, and characterization of three piperazine based multidentate ligands and their copper complexes. Ligands and complexes were characterized by UV–Vis, FT–IR, 1H NMR and mass spectra along with EPR spectra, molar conductance and thermogravimetric analysis (TGA). The metal complexes showed peaks corresponding to ligand to Cu(II) LMCT transition in UV–Vis spectrum. Molar conductance values of all complexes studied in water and DMSO indicated nonionic nature of complexes. TGA derivative curve represented the initial loss of water, which was in agreement of coordinated water in the proposed complexes. Four coordinated copper complexes were proposed on the basis of spectral data and supported by mass fragmentation pattern, isotopic distribution pattern, EPR, molar conductance and TGA. Ligands and complex geometries were optimized using DFT calculations and TDDFT studies of ligands were performed to corroborate the experimental UV–Vis spectrum. These ligands and complexes were tested for antibacterial activity and all complexes showed higher activity as compared to ligands. Antioxidant behavior of complexes was investigated by DPPH (2,2-diphenyl-1-picrylhydrazyl) method, and percentage inhibition data suggested two complexes Cu2L1 and Cu2L3 to hold fair antioxidant potential. In vitro cytotoxic studies of complexes performed on breast cancer cell line (MCF–7) using MTT calorimetric assay and IC50 value indicated good cytotoxic potential. BSA binding studies and DNA binding studies with CT-DNA were performed using UV–Vis titrimetric methods and were supported by molecular docking studies of complexes to investigate available binding interactions sites.