Spectroscopic and structural properties of complexes of 3,3′-bis(2-benzimidazolyl)-2,2′-bipyridine with copper(I) and silver(I)

Abstract

The pseudo-tetrahedral complexes [CuL 2 ]PF 6 ·7H 2 O·CH 3 OH (1) and [AgL 2 ]CF 3 SO 3 ·H 2 O (2) (L = 3,3′-bis(2-benzimidazolyl)-2,2′-bipyridine) have been synthesized and characterized through crystal structure analyses, electrochemistry, and spectroscopic methods. X-ray structural analyses of 1 and 2 indicate that sterically constrained N 4 ligands L are cis and behave as bidentate chelates to a single metal ion in a pseudo-tetrahedral fashion through the benzimidazole. As two benzimidazolyl rings exhibit considerable steric hindrance, the bipyridine unit of L remains uncoordinated. The pseudo-tetrahedral cation [CuL 2 ] + shows a quasi-reversible Cu I /Cu II oxidation-reduction wave in the CV in DMF (counter-ion PF 6 − ). The fluorescence titration of L with copper(I), silver(I), and also with pH have been conducted to examine the selectivity. The ligand shows remarkably high selectivity and sensitivity for Ag(I).

Spectroscopic, EPR, X-ray structural, and DFT studies of the complex compound of N4-donor ligand with copper(II)

“…The ligand, 6,6′-bis(NH-benzimidazol-2-yl)-2,2′-bipyridine (L) was prepared by a similar method previously reported by us [26] and others [10,11]. The ligand was characterized by MS (API-ES), 1 H and 13 C NMR spectroscopy.…”