Synthesis, characterization and biological activity of new Ni(II), Pd(II) and Cr(III) complex compounds with chlorhexidine

Abstract

Six new coordination compounds of Ni(II), Pd(II) and Cr(III) with chlorhexidine, 1,1?-hexamethylenebis[5-(4-chlorophenyl)biguanide], were prepared, characterized and examined for their potential as antimicrobial agents, as well as for their antioxidant activity. The metal complexes correspond to the formulas: [Ni(CHX)]Cl2?2H2O, [Ni(CHX)]Br2?2H2O, [Ni(CHX)](CH3COO)2?C2H5OH, [Pd(CHX)][PdCl4]?2H2O, [Pd(CHX)](CH3COO)2 and [Cr(CHX)Cl2](CH3COO), where CHX = chlorhexidine. Investigations on the in vitro antimicrobial activity of the complexes indicated that all have high activity against the tested bacteria, but are less active against fungi. Among the six complexes, those of Pd(II) showed the highest antibacterial activity, [Pd(CHX)][PdCl4]?2H2O being more active against Gram-positive and Gram-negative bacteria than chlorhexidine diacetate. The antioxidant activity of the metal complexes was investigated by photochemiluminescence and the results showed that the palladium( II) complexes have high antioxidant activities.