Square-pyramidal mononuclear, dinuclear and polymeric copper(II) complexes with (2-pyridinylmethyl)amino derivatives

Abstract

The coordination behavior of three ligand precursors 2-[(2-pyridinylmethyl)amino]acetic acid hydrochloride, 4-[(2-pyridinylmethyl)amino]benzoic acid hydrochloride and 4-{[2-(pyridin-2-ylmethylamino)ethylamino]methyl}benzoic acid hydrochloride, HL1∙HCl–HL3∙HCl, respectively, in copper(II) complexes is described. The complexes were characterized by elemental analysis, ESI mass spectrometry and IR spectroscopy, as well as X-ray structural analysis. The reaction of copper(II) with HL1∙HCl in methanol afforded the polymeric complex [{Cu(µ-Cl)2(MeL1-κ2N,N’)}n] (1) featuring the methyl ester of L1 (MeL1). With HL2∙HCl or HL3∙HCl, the dimeric complex [{CuCl(µ-Cl)(HL2-κ2N,N’)}2] (2) or the mononuclear complex [CuCl2(HL3-κ3N,N’,N’’)] (3) were obtained. All complexes exhibited square-pyramidal geometries. In 1, polymeric chains are formed through bridging chlorido ligands without typical hydrogen bonding interaction. Contrarily, the COOH group in 2 is participating in the formation of intermolecular hydrogen bonding forming a supramolecular structure. In 3, intermolecular hydrogen bonding (Cl…O) leads to a 1-D polymeric structure. The copper(II) complex 2 diminished viability of human 8505C, MCF-7, 518A2 and SW480 cell lines. The tumoricidal effect of 2 was realized mainly through caspase-mediated apoptosis.