Zinc(II) and mercury(II) coordination architectures with two pyridyl/benzimidazol-1-yl-based ligands: Crystal structures and photoluminescent properties

Abstract

In our efforts to investigate the relationships between the structures of ligands and their complexes, two structurally related ligands, 1-(2-pyridylmethyl)-1 H-benzimidazole ( L 1 ) and 1-(4-pyridylmethyl)-1 H-benzimidazole ( L 2 ), and their four complexes, [Zn( L 1 ) 2Cl 2] ( 1), [Hg( L 1 )Br 2] ∞ ( 2), {[Zn( L 2 )Cl 2](CH 3CN)} ∞ ( 3) and [Hg( L 2 )Br 2] 2(CH 3CN) 2 ( 4) were synthesized and structurally characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction analysis. Structural analyses show that 1 has a mononuclear structure, and 2 and 3 both take 1D structure. While 4 takes a dinuclear structure. 1, 2 and 4 were further linked into higher-dimensional supramolecular networks by weak interactions, such as C–H⋯Cl and C–H⋯Br H-bonding, C–H⋯π, and π⋯π stacking interactions. The structural differences of 1– 4 may be attributed to the difference of the spatial positions of the terminal N donor atoms in the pendant pyridyl groups in L 1 and L 2 , in which the pyridine rings may act as the directing group for coordination and the benzimidazole rings act as the directing group for π⋯π stacking and C–H⋯π interactions. The luminescent properties of the corresponding complexes and ligands have been further investigated.