Synthesis, structure, properties and computational study of a novel dumbbell-like zinc compound based on 2, 2′-biimidazole and 4, 4′-bipyridine mixed ligands

Abstract

Abstract A novel zinc compound with mixed ligands, Zn2(bipy)(bim)4·(ClO4)4·2H2O (1) (bipy = 4, 4′-bipyridine; bim = 2, 2′-biimidazole), was hydrothermally prepared and characterized by elemental analysis, IR spectroscopy, photoluminescence and single-crystal X-ray diffraction. Compound 1 is characteristic of an isolated structure with two five-coordinated zinc ions bridged by a bipy ligand to form a dumbbell-like motif. Compound 1 is of rhombohedral system, space group R-3 with a = 25.7698(5), c = 19.0359(7) Å, V = 10947.8(5) Å3, C34H36Cl4N18O18Zn2, Z = 9, M r = 1257.35, D c = 1.716 g/cm3, S = 1.045, μ(MoKα) = 1.298 mm–1, F(000) = 5742, R = 0.0489 and wR = 0.1337. Photoluminescence investigation reveals that compound 1 displays an emission band in the green region. In combination with the theoretical studies, it is believed that the emission must arise from the ligand-to-ligand charge-transfer (LLCT) transition.