Syntheses, structures and photoluminescent properties of Zn(ii) and Cd(ii) coordination polymers with flexible tripodal triazole-containing ligands

Abstract

Seven new coordination polymers, namely, [Zn2(o-bdc)2(L)2]·H2O (1), [Cd2(o-bdc)2(L)2]·6H2O (2), [Zn2(m-bdc)2(L)(H2O)] (3), [Cd2(m-bdc)2(L)]·2H2O (4), [Zn3(p-bdc)3(L)2]·H2O (5), [Zn2(btec)(L)2]·H2O (6) and [Cd2(btec)(L)2]·H2O (7) (o-H2bdc = 1,2-benzenedicarboxylic acid, m-H2bdc = 1,3-benzenedicarboxylic acid, p-H2bdc = 1,4-benzenedicarboxylic acid, H4btec = 1,2,4,5-benzenetetracarboxylic acid and L = 1,3,5-tris(1H-1,2,4-triazol-1-ylmethyl)-2,4,6-trimethylbenzene) have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Compound 1 displays a 1D ladder structure. The neighboring ladders are further linked by π–π interactions to form a 2D supramolecular layer. Compound 2 shows a 3D (3,5)-connected framework with (63)(66·84) topology. Compound 3 exhibits a 2D layer structure. The layers are further connected by hydrogen-bonds to give rise to a 3D supramolecular architecture. Compound 4 shows a 3D (4,5)-connected (4·85)(44·62·84)2 net. Compound 5 displays a 2D layer with self-penetrating characters. Hydrogen bonds among the water molecules and the p-bdc anions further link the layers into a 3D supramolecular architecture. Compound 6 displays a 2D sheet with dangling arms. Each sheet is threaded by the dangling arms of two others, leading to an unusual 3D polythreading framework. Compound 7 shows a 3D (3,4,5)-connected framework with (62·8)2(65·8)(65·84·10)2 topology. The photoluminescent properties of compounds 1–7 have been investigated in detail.