Metallacycle-based complexes based on a flexible pyridyl–benzimidazole derivative

Abstract

Three new coordination complexes, {Cd(pbmb)(NO3)2} n (1), {Ag(pbmb)(NO3)(C3H6O)} n (2), and {Hg2(pbmb)2Cl4} n (3), have been synthesized under solvothermal or solution reactions based on a flexible N-heterocyclic ligand 1-((2-(pyridin-4-yl)-1H-benzoimidazol-1-yl)methyl)-1H-benzotriazole (pbmb) and structurally characterized by single-crystal X-ray diffraction, IR spectrum, and elemental analyses. Both 1 and 2 display a 1-D chain structure with metallacycle unit while 3 shows a binuclear cycle motif. The aromatic rings are directing groups for π ··· π stacking interactions. The π ··· π interactions and hydrogen bonds extend the simple chain structure and binuclear structure to 3-D supramolecular architectures. Complexes 1 and 3 exhibit strong luminescence in the solid state at room temperature whereas 2 shows fluorescence quenching.