Design of a Multifunctional Indium–Organic Framework: Fluorescent Sensing of Nitro Compounds, Physical Adsorption, and Photocatalytic Degradation of Organic Dyes

The detection of nitro compounds and removal of organic dyes remain urgent issues because they are poisonous to humans. Taking advantage of metal–organic framework (MOF) materials, we demonstrate herein an indium–organic framework (InOF) exhibiting sensitive fluorescence sensing of nitro compounds, prominent dye capture, and excellent photodegradation of dyes. By using 4,4′,4″-s-triazine-1,3,5-triyltri-p-aminobenzoate (TATAB), an amino-functionalized BTB-like linker, the 3D SNNU-110 structure ({[In3OCl(H2O)2(TATAB)2]}n) is formed. SNNU-110 shows a 3,6-connected 3,6T22 topology with TATAB and [In3O(CO2)6] tricapped trigonal-prismatic clusters as 3- and 6-connected nodes. Thanks to the fluorescence properties and amine recognition sites of TATAB, SNNU-110 exhibits excellent performance of fluorescence quenching for six electron-deficient nitroaromatics. The intercrossing 1D channels in SNNU-110 formed from the a- and b-axis directions with dimensions of about 18 Å × 11 Å can capture diverse cationic, anionic, or neutral dyes effectively. What is more, the existence of an inorganic [In3O] cluster enable SNNU-110 to be a good photocatalyst. Upon irradiation with a 300 W xenon lamp, SNNU-110 shows outstanding photocatalytic activity toward rhodamine B (RhB) and methylene blue (MB), and there was almost no degradation. The catalytic activity can retain about 94.6% (RhB) and 93.1% (MB), respectively. Overall, SNNU-110 fully demonstrates the power of multicomponent MOFs, which provide a feasible route for the design of functional materials toward to pollutant identification and removal applications.