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.