Synthesis, characterization, antibacterial and antioxidant activity of 1,5-bis(6-chloro-1H-benzimidazol-2-yl)pentan-3-one and its Fe(III), Co(II), Cu(II), Zn(II) and Ru(II) complexes

Abstract

A new bis-benzimidazole ligand, 1,5-bis(6-chloro-1H-benzimidazol-2-yl)pentan-3-one (L, C19H16Cl2N4O), and its complexes with Fe(III), Co(II), Cu(II), Zn(II) and Ru(II) chlorides are synthesized and characterized by elemental analysis, molar conductivity, magnetic moment, TGA, FT-IR, 1H-NMR, fluorescence and UV-visible spectroscopy. The spectral data suggest that the chelating ligand acted as tridentate towards to Cu(II) ion however bidentate in the other complexes. According to the molar conductance data, [Fe(L)2Cl2]Cl•2H2O and [Cu(L)Cl]Cl•2H2O complexes are 1:1 electrolytes whereas [Co(L)Cl2]•2H2O, [Zn(L)(Cl)2(H2O)]•H2O and [Ru(L)(DMSO)(H2O)Cl2] complexes are non-ionic. In addition, antibacterial and antioxidant activity of the compounds were tested. The Ru(II) and Co(II) complexes showed moderate activity against to all tested bacteria whereas the ligand itself had no activity. According to the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•) scavenging results, the Ru(II) complex of L had quite significant radical scavenging activity almost the same as that of 3,5-di-tert-4-butylhydroxytoluene (BHT), a commercial standard.