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

Seven new coordination polymers, namely, [Zn-2(o-bdc)(2)(L)(2)]center dot H2O (1), [Cd-2(o-bdc)(2)(L)(2)]center dot 6H(2)O (2), [Zn-2(m-bdc)(2)(L)(H2O)] (3), [Cd-2(m-bdc)(2)(L)]center dot 2H(2)O (4), [Zn-3(p-bdc)(3)(L)(2)]center dot H2O (5), [Zn-2(btec)(L)(2)]center dot H2O (6) and [Cd-2(btec)(L)(2)]center dot H2O (7) (o-H(2)bdc = 1,2-benzenedicarboxylic acid, m-H(2)bdc = 1,3-benzenedicarboxylic acid, p-H(2)bdc = 1,4-benzenedicarboxylic acid, H(4)btec = 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 pi-pi interactions to form a 2D supramolecular layer. Compound 2 shows a 3D (3,5)-connected framework with (6(3))(6(6).8(4)) 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 (4.8(5))(4(4).6(2).8(4))(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 (6(2).8)(2)(6(5).8)(6(5).8(4).10)(2) topology. The photoluminescent properties of compounds 1-7 have been investigated in detail.