Double Cationization Approach toward Ionic Metal–Organic Frameworks with a High Bromide Content for CO₂ Cycloaddition to Epoxides

Abstract

Solid catalysts for CO 2 cycloaddition to epoxides often require homogeneous halide anions in large amounts, which sacrifice the heterogeneity and ecofriendliness. Here, we demonstrate a novel approach to ionic metal−organic frameworks (IMOFs) with a high bromide content, which utilizes two convenient postsynthetic "click" reactions (alkyne−azide cycloaddition and triazole N-alkylation) to install both pyridinium and triazolium groups and thus to include more bromides. The catalytic performance of various neutral and ionic MIL-101-based MOFs with different bromide-to-metal ratios and functional groups was compared. The doubly cationized IMOF with the high bromide-to-metal ratio can efficiently catalyze the cycloaddition reaction under relatively mild conditions with good recyclability. We also demonstrated the catalytic activity of the triazole group in the absence of nucleophilic anions. The results can not only provide a new approach to highly active and fully heterogeneous catalysts for the carbon fixation reaction but can also have important implications for development of IMOFs for other applications.

Nanochannel {InZn}–Organic Framework with a High Catalytic Performance on CO2 Chemical Fixation and Deacetalization–Knoevenagel Condensation

“…As shown in Figure S6, NUC-42a exhibits moderate CO 2 uptake performances of 46.6 and 94.5 cm 3 g –1 at 198 and 273 K, respectively, which are comparable to those of some reported MOFs. , Furthermore, to assess the bonding force of CO 2 and the framework, the adsorption heat ( Q st ) was calculated by using a viral method. As illustrated in Figure S7, the Q st value at zero loading is observed to be 19.2 kJ mol –1 , showing a relatively weaker interaction between CO 2 and the framework than those of some reported MOF-based materials. − These results demonstrate that physisorption to CO 2 plays the main role for the presented NUC-42a . Meanwhile, the relatively low adsorption heat suggests that desorption/adsorption regeneration is easily carried out.…”

Copper-Cluster-Based MOF as a Heterogeneous Catalyst for CO2 Chemical Fixation and Azide–Alkyne Cycloaddition

“…As a new class of porous materials, metal–organic frameworks (MOFs) exhibit great potential for CO 2 fixation due to their several advantages of well-ordered aperture, open metal sites, CO 2 adsorption ability, and recyclable utilization. , So far, some MOFs have been explored for catalytically fixing CO 2 into cyclic carbonates; however, high temperature, high CO 2 pressure, and complex separated operation in the procedure set obstacles to their further applications (Table S1). − Thus, exploring efficient and eco-friendly novel MOF-based materials for catalyzing the chemical conversion of CO 2 under mild conditions is of significance and challenging.…”

Cobalt Porphyrin-Cross-Linked Poly(Ionic Liquid)s as Efficient Heterogeneous Catalysts for Carbon Dioxide Conversion under Mild Conditions

“…However, for styrene oxide and phenyl glycidyl ether, a relatively lower conversion is produced, presumably due to their larger steric hindrance (entries 3 and 5), which have also been reported by several studies. 51,52 In addition, the electron-donation effect of the phenyl group may enhance the electronegativity of the carbon center, which is disadvantageous for X − attacking and thus deactivates the process compared with the allyloxy group. The above results show good substrate universality of the bifunctional catalysts.…”