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

The syntheses and characterization of three new copper(II) compounds 1–3 with a nonheme N,N′-di(quinolin-8-yl)cyclohexane-1,2-diamine (BQCNH2) and coligands 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) are reported. Antibacterial properties of 1–3 using two bacterial pathogens viz. E. coli and S. aureus are investigated. [Display omitted] •Cu(II) compounds of N,N′-di(quinolin-8-yl)cyclohexane-1,2-diamine (BQCNH2) are reported.•All compounds are characterized by spectral, thermal and electrochemical methods.•Cu(II) in [Cu(BQCNH2)(CH3CN)]2+1 exhibits trigonal bipyramid geometry.•[Cu(BQCNH2)L]2+ (L = bpy in 2; phen in 3) are distorted octahedral compounds.•Antibacterial studies reveal a better activity of 3 as compared to 1 and 2. Three new compounds of copper(II) viz. [Cu(BQCNH2)(CH3CN)](ClO4)2·CH3CN 1, [Cu(BQCNH2)(bpy)](ClO4)22 and [Cu(BQCNH2)(phen)](ClO4)2·2H2O 3 (BQCNH2 = 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 CH3CN and water respectively for 1 and 3. Both 2 and 3 crystallize in the centrosymmetric monoclinic space group P21/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 {CuN6} octahedron while the tetradentate BQCNH2 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 NH⋯O, CH⋯O interactions. In compound 3, OH⋯O interactions due to lattice water are additionally observed. Density functional theory (DFT) reveals a distorted 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.