Synthesis, spectroscopic, thermal, and biological activities on solvatochromic mixed ligand copper(II) complexes

A series of solvatochromic copper(II) mixed ligand complexes of 3-acetylcoumarine (3-ACoum) and dinitrogen bases (L), with the general formula Cu(3-ACoum)(L)Xn; where n = 2, L = N,N,N',N''-tetramethylethylenediamine (tmen), 1,10-phenanthroline (phen) and 2,2'-bipyridine (bipy) and X =  [image omitted],  [image omitted] or  [image omitted], have been synthesized and characterized by elemental analysis, IR, UV-Vis, electron spin resonance spectra, magnetic susceptibility, and conductivity measurements. The d-d absorption bands of tmen-complexes in weak donor solvents show the formation of square planar or square pyramidal geometries, while strong donor solvents yield octahedral complexes. The observed solvatochromism is mainly due to the solute-solvent interaction between the chelate cation and the solvent molecules, and the spectra displayed the possibility of using these complexes as Lewis base indicators. Thermogravimetric analyses (TGA)/differential thermal analysis (DTA) as well as the kinetic parameters (ΔH#, ΔS#, and ΔG#) of thermal decomposition stages of nitrate complexes have been calculated. Furthermore, the antimicrobial activity of the ligand and its complexes as inhibiting agents have been screened in vitro against two kinds of pathogenic bacteria and plant pathogenic fungi.