Microporous Cd(II) Metal–Organic Framework for CO₂ Catalysis, Luminescent Sensing, and Absorption of Methyl Green

Abstract

A new porous metal–organic framework (MOF) {[Cd­(Hbptc)]·H2O} n (Cdbptc) was assembled by Cd­(II) ions and a rigid (1,1′-biphenyl)-2,4,6-tricarboxylic acid (H3bptc) ligand via a solvothermal method. Cdbptc was studied by the physical and chemical analyses methods, exhibiting captivating three-dimensional (3D) microporosity with a 1D channel of 1.7 nm decorated by the uncoordinated hydroxyl groups. It is worth noting that clusters were formed by Cd­(II) ions as the Lewis active sites, making it as an excellent reused homogeneous catalyst for the CO2 cycloaddition reaction. In addition, the fluorescence study of Cdbptc indicated Cr3+, Cu2+, Fe3+, [Fe­(CN)6]3–, and Cr2O7 2– ions could be multiply detected with a low detection limit. Besides, the dye adsorption experiment demonstrated that methyl green (MG) dye could be selectively adsorbed by Cdbptc from other dyes, and the adsorption mechanism was testified by X-ray photoelectron spectroscopic data and Fourier transform infrared spectrum data.

Bifunctional {Pb10K2}–Organic Framework for High Catalytic Activity in Cycloaddition of CO2 with Epoxides and Knoevenagel Condensation

“…Based on the related studies on the MOF-based catalysis and the microstructure characteristics of NUC-45a , the speculated mechanism is shown in Figure . − First, epoxide and CO 2 molecules are weakly contacted by the exposed metal sites, N pyridine atoms, and μ 2 -OH groups from activated [Pb 10 K 2 (μ 2 -OH) 2 (COO) 14 ] clusters in the confined space. Then, the Br – anion liberated by n -Bu 4 NBr poses a nucleophilic attack on the less-hindered carbon atom of epoxide to form the anionic intermediates of bromoalkoxide, which tends to be inserted by a polarized CO 2 molecule, generating the alkylcarbonate salt.…”

“…Knoevenagel condensation is a typical C–C bond coupling reaction, and its mechanism is that the methylene group in advance activated by two electron-withdrawing groups reacts with a carbonyl group to form a covalent CC bond. − This reaction is usually used for the synthesis of fine chemicals and pharmaceuticals. Accumulating evidence suggests that the metal centers as Lewis acid sites and the nucleophilic groups as Lewis base sites in porous MOFs could effectively catalyze the Knoevenagel reaction through a synergistic effect. − Therefore, in the Knoevenagel condensation reaction, the catalytic performance of activated porous NUC-45a was investigated. To determine the optimal reaction conditions of the catalytic reaction, benzaldehyde (10 mmol) and malononitrile (20 mmol) were selected as the substrates, shown in Table .…”

Nanocage-Based Tb3+-Organic Framework for Efficiently Catalyzing the Cycloaddition Reaction of CO2 with Epoxides and Knoevenagel Condensation

“…Combining the structure of NUC-58 and the hypothetical mechanism reported in recent years, − the reaction mechanism is speculated in Figure b. First, the multicomponent active sites of exposed metal sites, N pyridine atoms, and μ 2 –OH groups in the confined hole polarize the substrate molecules of epoxides and CO 2 through intermolecular forces, lowering their activation energy levels.…”

Metal–Organic Framework-Based Selective Molecular Recognition of Organic Amines and Fixation of CO2 into Cyclic Carbonates

“…Notably, we observed a major enhancement in the fluorescence intensity compared to free ligand L and coligands H 2 oba and 5-H 2 nipa. The emission peak shown by the studied MOFs may be credited to the intraligand π–π* transition, wherein the enhancement in the fluorescence intensity could be principally attributed to the interactions between the π-electron-rich framework of ligands and Zn 2+ /Cd 2+ metal ions. ,,− In addition, we have also recorded the solid-state fluorescence profiles of Zn-MOF- 1 and Cd-MOF- 2 at room temperature to rationalize the photoluminescent nature of d 10 metal-based materials in the solid state. As shown in Figure S15, both MOFs exhibit a broad emission peak between 330 and 450 nm when excited at 290 nm.…”