Synthesis, catalase, superoxide dismutase and antitumour activities of copper(II) carboxylate complexes incorporating benzimidazole, 1,10-phenanthroline and bipyridine ligands: X-ray crystal structures of [Cu(BZA) 2(bipy)(H 2O)], [Cu(SalH) 2(BZDH) 2] and [Cu(CH 3COO) 2(5,6-DMBZDH) 2] (SalH 2 = salicylic acid; BZAH = benzoic acid; BZDH = benzimidazole and 5,6-DMBZDH = 5,6-dimethylbenzimidazole)

Abstract

A series of simple Cu(II) carboxylate complexes {carboxylate = acetate (CH 3COO), salicylate (salH) or benzoate (BZA)}, some containing either one chelating {1,10-phenanthroline (phen) or 2,2′-bipyridine (bipy)} or two monodentate {benzimidazole (BZDH) or 5,6-dimethylbenzimidazole (5,6-DMBZDH)} nitrogen donor ligands, have been prepared and characterised. X-ray crystal structures have been determined for the square pyramidal complex [Cu(BZA) 2(bipy)(H 2O)] and the two square planar complexes [Cu(CH 3COO) 2 (5,6-DMBZDH) 2] and [Cu(salH) 2(BZDH) 2]. All of the complexes are poor catalase mimics in the presence of imidazole and totally inactive in its absence. The complexes all exhibit excellent superoxide dismutase (SOD) mimetic activity and the two phen derivatives [Cu(CH 3COO) 2(phen)] and [Cu(sal)(phen)] display potent in vitro cytotoxicity against human hepatic (Hep-G), renal (A-498) and lung (A-549) cancer cell lines.