Fluorine-Functionalized NbO-Type {Cu₂}-Organic Framework: Enhanced Catalytic Performance on the Cycloaddition Reaction of CO₂ with Epoxides and Deacetalization-Knoevenagel Condensation

Abstract

The high catalytic activity of metal–organic frameworks (MOFs) can be realized by increasing their effective active sites, which prompts us to perform the functionalization on selected linkers by introducing a strong Lewis basic group of fluorine. Herein, the exquisite combination of paddle-wheel [Cu2(CO2)4(H2O)] clusters and meticulously designed fluorine-funtionalized tetratopic 2′,3′-difluoro-[p-terphenyl]-3,3″,5,5″-tetracarboxylic acid (F-H4ptta) engenders one peculiar nanocaged {Cu2}-organic framework of {[Cu2(F-ptta)­(H2O)2]·5DMF·2H2O} n (NUC-54), which features two types of nanocaged voids (9.8 Å × 17.2 Å and 10.1 Å × 12.4 Å) shaped by 12 paddle-wheel [Cu2(COO)4H2O)2] secondary building units, leaving a calculated solvent-accessible void volume of 60.6%. Because of the introduction of plentifully Lewis base sites of fluorine groups, activated NUC-54a exhibits excellent catalytic performance on the cycloaddition reaction of CO2 with various epoxides under mild conditions. Moreover, to expand the catalytic scope, the deacetalization-Knoevenagel condensation reactions of benzaldehyde dimethyl acetal and malononitrile were performed using the heterogenous catalyst of NUC-54a. Also, NUC-54a features high recyclability and catalytic stability with excellent catalytic performance in subsequent catalytic tests. Therefore, this work not only puts forward a new solution for developing high-efficiency heterogeneous catalysts, but also enriches the functionalization strategies for nanoporous MOFs.

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

“…Moreover, the cycloaddition was not found in the absence of NUC-45a and n -Bu 4 NBr (entry 19). In conclusion, the optimal reaction conditions were determined as follows: 65 °C, 0.10 mol % NUC-45a catalyst, 5 mol % n -Bu 4 NBr cocatalyst, and 6 h. It is mentioning that compared with the recent research of MOF catalysts, − the inner wall of Pb­(II)-based NUC-45a had massive coexisting Lewis acid–base sites (Lewis acid sites including Pb 2+ and K + , Lewis base sites including the μ 2 -OH group and N pyridine atom), which made it have higher adsorptivity for CO 2 and display better catalytic performance.…”

Nanocage-based {In2Tm2}-organic framework for efficiently catalyzing the cycloaddition reaction of CO2 with epoxides and Knoevenagel condensation

“…4. 67–71 Firstly, the cycloaddition reaction began with the O atom of epoxide being activated by the Lewis acidic In 3+ and Tm 3+ sites to form In/Tm-epoxide adducts, resulting in the instability of the ternary rings. Subsequently, the Br − ions released from the co-catalyst of n -Bu 4 NBr launched an affinity attack on the C atom with less steric hindrance to produce the main intermediates of alkylcarbonate anions, whose O − atoms served as a nucleophilic reagent to react with CO 2 in the pores, generating the carbonate ester as the secondary intermediate.…”

A multifunctional [CdI4]2−·[H2Bimb]2+complex to probe high performance photocatalytic degradation of methyl violet and fluorescent detection of Cr2O72−and Hg2+ions

“…Non-covalent interactions are useful in crystal engineering, molecular identification, catalysis, drug designing, and selfassembly because they play an important role in cooperative effects in several macromolecular systems. [1][2][3][4] Non-covalent interactions in inorganic-organic hybrids disclose ferroelectricity, magnetism, optical properties, heterogeneous catalysis [5][6][7] and other traits due to the design ability and controllable characteristics of the inorganic and organic constituents. [8][9][10] Physical, chemical, and biological systems can all benefit from these non-covalent interactions.…”