Synthesis, characterization and antimicrobial properties of mononuclear copper(II) compounds of N,N'-di(quinolin-8-yl)cyclohexane-1,2-diamine

Abstract

Three new compounds of copper(II) viz. [Cu(BQCNH sub(2))(CH sub(3) CN)](ClO sub(4))2.CH sub(3) CN 1, [Cu(BQCNH sub(2))(bpy)](ClO sub(4)) sub(2) 2 and [Cu(BQCNH sub(2))(phen)](ClO sub(4)) sub(2).2H sub(2) O 3 (BQCNH sub(2) = N,N'-di(quinolin-8-yl)cyclohexane-1,2-diamine, bpy = 2,2'-bipyridine and phen = 1,10-phenanthroline) were synthesized and characterized by IR, UV-Vis, ESI-MS, EPR spectroscopy, cyclic voltammetry, magnetic and thermogravimetric analyses and X-ray diffraction. Thermal studies reveal loss of two molecules of CH sub(3) CN and water respectively for 1 and 3. Both 2 and 3 crystallize in the centrosymmetric monoclinic space group P2 sub(1)/n and the central metal exhibits a distorted octahedral geometry. The bidentate ligands (bpy in 2 and phen in 3) occupy cis positions of the {CuN sub(6)} octahedron while the tetradentate BQCNH sub(2) ligand spans the remaining vertices of the octahedron. The perchlorate anions and the hexacoordinate Cu(II) species in 2 and 3 are interlinked with the aid of several N-H...O, C-H...O interactions. In compound 3, OH...O interactions due to lattice water are additionally observed. Density functional theory (DFT) reveals a trigonal bipyramidal geometry for 1. Antimicrobial properties of 1-3 against two bacterial pathogens viz. E. coli and S. aureus were investigated. Compound 3 exhibits better activity as compared to 1 and 2.