Synthesis, spectroscopic characterization and in vitro studies of new heteroleptic copper (II) complexes derived from 2-hydroxy napthaldehyde Schiff's bases and N, N donor ligands: Antimicrobial, DNA binding and cytotoxic investigations

A series of eight new copper (II) complexes of types [Cu(HL1)(B)] (4a-4d) and [Cu(HL2)(B)] (4e-4h), where HL1 is N-(2-hydroxy-1-naphthalidene)-2-aminophenol, HL2 is N-(2-hydroxy-1-naphthylidene)-2- mercaptoaniline and B is N, N donor ligands viz bipyridyl (bpy), 1,10-phenanthroline (phen), dipyridoquinoxaline (dpq) and dipyridophenazine (dppz) have been synthesized and characterized by elemental analysis as well as by spectroscopic techniques (IR, UV, ESI mass and EPR spectra). The DNA-binding properties of these copper complexes (4a-4h) have been investigated by electronic absorption, viscosity measurements and docking analyses. The results obtained indicated that the complexes get bonded with DNA via an intercalation binding mode with an intrinsic binding constant, K-b (1.116 +/- 0.21 to 7.227 +/- 0.21) x 10(4) M-1. The antimicrobial activity assays with the Schiff's bases and their heteroleptic copper (II) complexes of 4a and 4b exhibited profound activity against gram positive bacteria, gram negative bacteria and fungi. Further, complexes 4d and 4h displayed significant cytotoxicity when examined in vitro on a panel of cancerous cell line - human liver cancer cell line - HepG-2 cells (IC50 = 40.82 and 29.74 lg/ml). (C) 2015 Elsevier B.V. All rights reserved.