Synthesis, spectroscopic characterization, and biological screening of binuclear transition metal complexes of bicompartmental Schiff bases containing indole and resorcinol moieties

A series of binucleating Cu(II), Ni(II), and Zn(II) complexes of bicompartmental ligands with ONO donors were prepared. The ligands were synthesized by the condensation of 5-substituted-3-phenyl-1H-indole-2-carboxyhydrazides and 4,6-diacetylresorcinol. The newly synthesized ligands and their complexes were characterized by elemental analysis and various spectral studies like IR, ^1H NMR, ESI-mass, UV-Vis, ESR, thermal studies, magnetic susceptibility, molar conductance, and powder-XRD data. All the complexes were binuclear and monomeric in nature. Cu(II) complexes have octahedral geometry, whereas Ni(II) and Zn(II) complexes have square planar and tetrahedral geometry, respectively. The redox property of the Cu(II) complex was investigated by electrochemical method using cyclic voltammetry. In order to evaluate the effect of metal ions upon chelation, both the ligands and their metal complexes were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleaving capacity of all the complexes was analyzed by agarose gel electrophoresis.