Solvent-Regulated Formation of Metal/Metal-Oxo Nodes in Two Indium Metal-Organic Frameworks: Syntheses, Structures, Selective Gas Adsorption and Fluorescence Sensor Properties.

Two water-stable indium metal-organic frameworks, (NH ₂ Me ₂ ) ₃ [In ₃ (BTB) ₄ ] ⋅ 12DMA ⋅ 4.5H ₂ O (In-MOF-1) and (NH ₂ Me ₂ ) ₉ [In ₉ O ₆ (BTB) ₈ (H ₂ O) ₄ (DMSO) ₄ ] ⋅ 27DMSO ⋅ 21H ₂ O (In-MOF-2) (BTB=4,4',4''-benzene-1,3,5-tribenzoate) with 3D interpenetrated structure has been constructed by regulating solvents. Structure analysis revealed that In-MOF-1 has a three-dimensional (3D) structure with a single metal core, while In-MOF-2 features an octahedron cage constructed by three kinds of metal clusters to further form a 3D structure. The fluorescence investigations showed that In-MOF-1 and In-MOF-2 are potential MOF-based fluorescent sensors to detect acetone and Fe ³⁺ ions in EtOH or water with high sensitivity, excellent selectivity, recyclability and a low limit of detection. Moreover, the fluorescence mechanisms of In-MOF-1 and In-MOF-2 toward acetone and Fe ³⁺ ions were further explained. In addition, In-MOF-2 has higher thermal and framework stability than In-MOF-1. The activated In-MOF-2 presents a high BET surface area of 998.82 m ² g ^-1 and a pore size distribution of 8 to 16 Å. At the same time, In-MOF-2 exhibits high selective CO ₂ adsorption for CO ₂ /CH ₄ and CO ₂ /N ₂ , respectively. Furthermore, the adsorption sites and adsorption isotherms were predicted using grand canonical Monte Carlo (GCMC) simulations, and the adsorption energy of the lowest-energy adsorption configuration was calculated using molecular dynamics (MD) simulations.
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