Controllable Synthesis of Tb^III Metal–Organic Frameworks with Reversible Luminescence Sensing for Benzaldehyde Vapor

Abstract

Two novel lanthanide metal-organic frameworks (MOFs) with the formulas [Tb(bidc)(Hbidc)(H₂O)]_<i>n</i> (<b>JXUST-20</b>) and {[Tb₃(bidc)₄(HCOO)(DMF)]·solvents}_<i>n</i> (<b>JXUST-21</b>) were synthesized based on 2,1,3-benzothiadiazole-4,7-dicarboxylic acid (H₂BTDC) under solvothermal conditions. Interestingly, benzimidazole-4,7-dicarboxylic acid (H₂bidc) was formed in situ using H₂BTDC as the starting material. The self-assembly process of the targeted MOFs with different topological structures can be controlled by the solvents and concentration of the reactants. Luminescence experiments show that <b>JXUST-20</b> and <b>JXUST-21</b> exhibit strong yellow-green emission. <b>JXUST-20</b> and <b>JXUST-21</b> can selectively sense benzaldehyde (BzH) via a luminescence quenching effect with detection limits of 15.3 and 1.44 ppm, respectively. In order to expand the practical application of MOF materials, mixed-matrix membranes (MMMs) have been constructed by mixing targeted MOFs and poly(methyl methacrylate) in a <i>N</i>,<i>N</i>-dimethylformamide (DMF) solution, which can also be used for BzH vapor sensing. Therefore, the first case of MMMs derived from Tb^III MOFs has been developed for the reversible detection of BzH vapor, providing a simple and efficient platform for the future detection of volatile organic compounds.