Four Novel Three-Dimensional Triazole-Based Zinc(II) Metal−Organic Frameworks Controlled by the Spacers of Dicarboxylate Ligands:  Hydrothermal Synthesis, Crystal Structure, and Luminescence Properties

Abstract

Four novel mixed-ligand metal−organic frameworks (MOFs), [Zn 5 (μ 3 -OH) 2 (BTA) 2 (tp) 3 ] n ( 1 ), [Zn(BTA)(chdc) 0.5 ] n ( 2 ), [Zn(BTA)(ap) 0.5 ] n ( 3 ), and [Zn(BTA)(gt) 0.5 ] n ( 4 ) (BTAH = benzotriazole, H 2 tp = terephthalic acid, H 2 chdc = 1,4-cyclohexanedicarboxylic acid, H 2 ap = adipic acid, and H 2 gt = glutaric acid), have been synthesized by the reaction of zinc(II) chloride and BTAH with four different aromatic/aliphatic binary acids under similar hydrothermal conditions. All these compounds are fully structurally characterized by elemental analysis, IR, single-crystal X-ray crystallography, and the bulk new materials were further identified by X-ray powder diffraction. Their compositional stability and photoluminescence properties were further investigated to establish the structure−properties relationships. Structural analysis reveals that 1 is a scarcely reported eight-connected three-dimensional (3-D) self-penetrating MOF with pentanuclear zinc clusters as secondary building units (SBUs); 2 is a 3-D infinite network with empty 34-membered hexanuclear zinc(II) metallamacrocycle channels; 3 and 4 are 3-D meso-racemic coordination polymers with a one-dimensional Zn - BTA helix chain motif, in which alternative right- and left-hand helical chains are linked together via ap for 3 and gt for 4 . The much higher compositional stability up to 436 °C and strong solid-state luminescence emissions suggest that 1 − 4 are good candidates for light emission materials.