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), [Zn5(μ3-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, H2tp = terephthalic acid, H2chdc = 1,4-cyclohexanedicarboxylic acid, H2ap = adipic acid, and H2gt = 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.