Synthesis and spectral characterization of 1,2-bis(5-methyl/chloro-1H-benzimidazol-2-yl)ethanols and their Co(II), Pd(II) and Zn(II) complexes

Abstract

1,2-Bis(5-methyl/chloro-1H-benzimidazol-2-yl)ethanols (1 and 2), asymmetric bis-benzimidazoles, and their complexes with CoCl2, PdCl2 and ZnCl2 were synthesized and characterized by elemental analysis, molar conductivity, magnetic moment, TGA, FT-IR (mid- and far-IR), FT-Raman, 1Hand 13C-NMR spectroscopy, ESI-MS and fluorescence spectroscopy. The spectral data suggest that the chiral chelating ligands acted as tridentate through both the C=N nitrogen and OH oxygen atoms. According to the molar conductance, the Zn(II) complexes are non-electrolyte whereas the Co(II) complexes are 1:2 and the Pd(II) complexes are 1:1 electrolytes. The ligands and most of the complexes show triple fluorescence in ethanol. In addition, the Zn(II) complex of 1 (1c) shows significant fluorescence characteristics compared to the other complexes.