Spectral characterization, X-ray structure and biological investigations of copper(II) ternary complexes of 2-hydroxyacetophenone 4-hydroxybenzoic acid hydrazone and heterocyclic bases

Abstract

Two new heterocyclic base adducts of copper(II) complexes of the general formula CuLB, where L is the dianion of 2-hydroxyacetophenone 4-hydroxybenzoic acid hydrazone and B is the heterocyclic base, 2,2 ′-bipyridine (bipy) or 1,10-phenanthroline (phen), have been synthesized and characterized by different physicochemical methods. The molar conductivity measurements in DMF solution indicate the non-electrolyte nature of both complexes. The electronic and IR spectroscopic data indicate that the complexes have square pyramidal geometry with one dibasic tridentate ligand L 2− and one bidentate heterocyclic base. The coordination takes place through the deprotonated hydroxyl group, azomethine nitrogen and oxygen from the hydrazide moiety. The magnetic susceptibility values at room temperature are consistent with the spin only value for monomeric copper(II) species. EPR studies of all compounds gave axial spectra. Simulation EPR spectra gave the best values for g and A for each compound. The g values indicate that the unpaired electron resides in the d x 2− y 2 orbital. The crystal and molecular structure of CuLphen was determined by the single crystal X-ray diffraction method. Investigations on antimicrobial activities showed that the compounds are moderately active against Gram negative bacteria.