A series of entangled ZnII/CdII coordination polymers constructed from 1,3,5-benzenetricarboxylate acid and flexible triazole ligands

Abstract

Five new coordination polymers, namely, [Zn(HBTC)(L₁)]·4H₂O (1), [Zn₃(BTC)₂(L₂)₂(H₂O)₂]·2H₂O (2), [Zn(HBTC)(L₃)] (3), [Cd(HBTC)(L₁)(H₂O)]·H₂O (4) and [Cd(H₂BTC)₂(L₃)₂]·2H₃BTC (5) (H₃BTC = 1,3,5-benzenetricarboxylic acid, L₁ = 1,6-di(1,2,4-triazol-1-yl)hexane, L₂ = 1,3-di(1,2,4-triazol-1-yl)propane and L₃ = 1,3-bis((1,2,4-triazol-1-yl)methyl)benzene) have been successfully isolated under hydrothermal conditions. Compound 1 exhibits a rare 2D → 3D entangled structure with the coexistence of polycatenation and interdigitation. Compound 2 contains new trinodal (5.6²)(5².6)(5⁴.8²) layers and features a 2D → 2D entangled network with the coexistence of polycatenation and polythreading motifs. Compound 3 shows a 2D → 2D polythreaded framework. When O–H⋯O hydrogen-bonding interactions are taken into consideration, the framework of 3 can be regarded as a 2-fold interpenetrating hms network. Compound 4 displays an unusual 2D → 3D interdigitated framework. Compound 5 displays a 1D chain structure. The thermal stabilities and fluorescence properties of compounds 1–5 have been investigated.