The C–H⋯Cl2Cu(II) synthon in the structural direction and assembly of supramolecular complexes with the 3,3′-bis(2-benzimidazolyl)-2,2′-dipyridine ligand and its N-substituted derivatives

Abstract Three new Cu(II) supramolecular complexes [Cu( L 1 )Cl 2 ]·2DMF ( 1 ), [Cu( L 2 )Cl 2 ] ( 2 ) and [Cu( L 3 )Cl 2 ]·DMF ( 3 ) ( L 1  = 3,3′-bis(2-benzimidazolyl)-2,2′-dipyridine, L 2  = 3,3′- bis(N-ethyl-2-benzimidazolyl)-2,2′-dipyridine and L 3  = 3,3′-bis(N-benzyl-2-benzimidazolyl)-2,2′-dipyridine) have been prepared and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. X-ray structural analysis of L 1 , L 2 ·3.5H 2 O and L 3 ·H 2 O indicates that all three ligands adopt the trans conformation with the two benzimidazole fragments located on opposite sides of the dipyridyl backbone. While in complexes 1 – 3 , all the ligands display the cis conformation and behave as bidentate chelating reagents to coordinate with Cu(II). The inorganic chloride ions always act as a reliable hydrogen bonded acceptor in these structures, and the resulting C–H⋯Cl 2 Cu supramolecular synthons play a significant role in the formation and stabilization of the structures. Moreover, additional non-covalent interactions, such as C–H⋯π, are also identified to extend the discrete (0-D) or low-dimensional (1-D) motifs into high-dimensional architectures.