Syntheses, structures, luminescent and gas adsorption properties of five new interpenetrated, 2D and 3D metal–organic frameworks based on a semi-rigid bis(imidazole)-carbazole ligand

Abstract

We have succeeded in constructing five metal–organic frameworks, [Zn(L)SO4] (1), [Zn(L)(bdc)]·H2O (2), [Zn(L)(abdc)]·0.5H2O (3), [Zn(L)(oba)]·2H2O (4) and [Zn(L)2(suc)2] (5), based on a semi-rigid bis(imidazole)-carbazole ligand [9-ethyl-3,6-di(1H-imidazol-1-yl)-9H-carbazole (L)] and five rigid/flexible dicarboxylic acids (DPac=2,6-pyridine dicarboxylic acid, H2bdc=p-phthalic acid, H2abdc=azobenzen-4,4′-dicarboxylate, H2oba=4,4-oxybisbenzoic acid and H2suc=succinic acid). Complexes 1–5 were characterized by single crystal X-ray diffraction, elemental analysis, power X-ray diffraction (PXRD), IR spectroscopy and thermogravimetry. Complex 1 possesses a two-dimensional (2D) network which is constructed not by the co-ligand acid but by a sulfate anion. Both complexes 2 and 3 are two-dimensional (2D) sheet structures with 2D→3D polycatenation frameworks. Coordination polymer 2 contains interconnected 70-membered macrocycles and 3 forms a double helix-like 4-fold interpenetrated network. Complex 5 exhibits a three-dimensional (3D) sra network. The luminescent properties of 1–5 in the solid state and gas adsorption properties of 3 and 5 were also investigated.