New copper(II) complexes of 2-hydroxyacetophenone N(4)-substituted thiosemicarbazones and polypyridyl co-ligands: structural, electrochemical and antimicrobial studies

摘要

Seven new copper(II) complexes of 2-hydroxyacetophenone N(4)-substituted thiosemicarbazones (H2L) and bidentate polypyridyl compounds 2,2'-bipyridine and 1,10-phenanthroline (B) were prepared and characterized. The thiosemicarbazones bind to the metal as dianionic ONS donors (L2-) and yield compounds of the stochiometry [MLB]. The structure of the compound [Cu(L-4)(2,2'-bipy)] (6) was investigated by single-crystal X-ray diffraction method. Spin Hamiltonian and bonding parameters of the compounds calculated from the EPR spectra suggest square pyramidal (SPY) structure for the compounds. The g values predict geometry of C-4v symmetry with B-1g ground state. The bonding parameters show significant in-plane pi-bonding. The cyclic voltam-metric study of the complexes shows irreversible redox peaks corresponding to Cu(II/I) couple and quasi-reversible redox peaks corresponding to copper(II/III) oxidation. The thiosemicarbazones and their copper complexes show significant growth inhibitory activity against bacteria Escherichia coli, Staphylococcus aureus, and fungi Candida albicans and Aspergillus flavus. (C) 2004 Elsevier Ltd. All rights reserved.