Synthesis, spectral properties, crystal structures and biological activity of copper(II) pyridinecarboxylates with N-heterocyclic ligands

摘要

Synthesis and characterization of four new 2,6-dimethoxynicotinate (2,6-(MeO)_2nic) copper(II) monomeric complexes [Cu(2,6-(MeO)_2nic)_2(py)_2] (py is pyridine), [Cu{2,6-(MeO)_2nic}_2(Etnic)_2(H_2O)] (Etnic is ethylnicotinate), [Cu{2,6-(MeO)_2nic}_2(Et_2nia)_2(H_2O)_2] (Et_2nia is N,N-diethylnicotinamide) as well as of the polymeric complex [Cu{2,6-(MeO)_2nic}_2(ron)_2]_n (ron is ronicol) are reported. The characterizations were based on elemental analysis, infrared, electronic and EPR spectra. Crystal structures of two of the complexes have been determined. The copper(II) of [Cu{2,6-(MeO)_2nic}_2(py)_2] has a distorted tetragonal-bipyramidal (4 + 2) coordination environment. Both 2,6-(MeO)_2nic anions are asymmetrically chelating. The Cu(II) of [Cu{2,6-(MeO)_2nic}_2(Etnic)_2(H_2O)] is pentacoordinate in a slightly distorted tetragonal-pyramidal arrangement by two trans nitrogens, each of one Etnic, by two oxygens, each of the carboxyl group of one unidentate 2,6-(MeO)_2nic and the axial position occupied by water at a longer distance. Antimicrobial effects of the complexes have been tested on various strains of bacteria, yeasts and filamentous fungi. While the 2,6-(MeO)_2nicH alone did not influence the model bacteria growth, dimeric [Cu{2,6-(MeO)_2nic}_2(H_2O)]_2 and polymeric [Cu{2,6-(MeO)_2nic}_2(ron)_2]_n have pronounced influence on the growth of Staphytococcus aureus, Escherichia coli and Candida parapsilosis.