Antimicrobial activities of two copper(Il) complexes with 4-(diethylamino)salicylaldehyde and a-diimine

Abstract

Two novel coppe(tr) complexes (Fig. 1) with 4-(diethylamino)salicylald.hyd. as ligand (HL) and o-diimine - 2,2'-bipyridine (bipy) or 1,lO-phenanthroline (phen) with potentially antimicrobial activity are described. Complex 1 is a mononuclear copper(Il) complex, [Cu(bipy)(L)]BF+.HzO, whereas complex 2 is a binuclear [Cu(phen)(L)]z(BF+)2. Antimicrobial activities of those complexes, coffesponding Cu(II) salt, o,-diimines (phen and bipy) and ligand HL were studied by examining the minimum inhibitory concentration (MIC) on four Gram-positive and four Gram-negative bacterial species and three fungal strains. Amikacin and fluconazole were used as the standard drugs for the comparison of the MIC values. Cu(II) complexes I and 2 demonstrated significantly stronger antibacterial activities than parent ligands (adiimines and HL) or starting Cu(II) salt. Complex 2 is the most active of all examined compounds. The activity of this complex against E. coli is comparable to the activity of the standard antibiotic amikacin. Unlike increasing antibacterial activity of complexes 1 and2 in regard to all coordinated ligands, antifungal activities showed the opposite trend.