Anthracene-triazole-dicarboxylate-Based Zn(II) 2D Metal Organic Frameworks for Efficient Catalytic Carbon Dioxide Fixation into Cyclic Carbonates under Solvent-Free Condition and Theoretical Study for the Reaction Mechanism

Abstract

Two ZnII-based metal organic frameworks (MOFs) [Zn 2 (L) 2 (1,2-bis­(4-pyridyl)­ethane) 4 ] n [(ZnMOF1)] and [Zn 2 (L) 2 (1,2-bis­(4-pyridyl)­ethene) 4 ] n [(ZnMOF2)] have been synthesized and crystallographically characterized. Due to the presence of Lewis acidic center Zn and basic functional groups (−NN) in both complex [(ZnMOF1)] and [(ZnMOF2)], it is possible to efficiently fix carbon dioxide into epoxides to produce biosource cyclic carbonates. Under solvent-free and mild reaction conditions (60 °C temperature and 1 bar CO2 pressure), various types of epoxides (terminal as well as internal epoxides) effectively undergo this catalytic reaction and produced high yield of the corresponding cyclic carbonate products. High turnover frequency was obtained for this CO2 fixation reaction of different epoxides, and the values are in the range of 72–234 h–1. The theoretical calculations are made by density functional theory (DFT) theory to achieve the relative energy of the intermediates and transition state and product which are engaged in each step of the catalytic reaction cycle, and the detailed mechanism of the reaction is presented. Moreover, the two MOF catalysts are easily recoverable and recyclable in nature. The efficiencies of both catalysts regain even after seven consecutive catalytic cycles. Overall, the work demonstrates the design and syntheses of two Zn­(II)­MOF catalysts for effective addition of CO2 into epoxides to produce cyclic carbonates and DFT study for the catalytic reaction mechanism.

An anthracene-9-carboxylic acid-based [Cu20] cluster templated by a bromine anion for heterogeneous catalytic chemical fixation of carbon dioxide

“…In order to further discuss the high activity of [Cu 20 ] in catalyzing the cycloaddition reaction of CO 2 and epoxides, since the interaction between epichlorohydrin and the metal sites played a key role in the reaction mechanism, the adsorption energies of both clusters with epichlorohydrin were calculated by the DFT method. 65–68 DFT calculation results demonstrated that the epichlorohydrin adsorption active sites were mainly attributed to the unsaturated Cu site in the [Cu 20 ] or [Cu 2 ] cluster (Fig. 3).…”

“…c Moles of cyclic carbonate per mole of catalyst [Cu 20 ]. d Moles of cyclic carbonate per mole of catalyst [Cu 20 ] per hour.both clusters with epichlorohydrin were calculated by the DFT method [65][66][67][68]. DFT calculation results demonstrated that the epichlorohydrin adsorption active sites were mainly attributed to the unsaturated Cu site in the [Cu 20 ] or [Cu 2 ] cluster (Fig.3).…”

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

“…As a result, the reaction efficiency could be almost negligible in the presence of potassium halide of KX (X = I, Cl, and Br) or NUC-58a , shown in entries 1–3. However, with the introduction of both n -Bu 4 NX (X = I, Cl, and Br) and NUC-58a , the catalytic conversion rate was significantly accelerated (entries 4–6), which should be attributed to the fact that the halide anion was conducive to the open-loop dynamic behavior. − Furthermore, entry 6 exhibited that n -Bu 4 NBr had the best catalytic activity, which should be due to the best combination of nucleophilic and dissociative behaviors. , What is more, the reactions with other bromides as co-catalysts were also carried out to replace n -Bu 4 NBr, as shown in entries 8–11. The lower conversion rate illustrated that n -Bu 4 NBr had the best synergistic catalytic effect.…”

CO2 Fixation by Dimeric Tb(III) Complexes: Synthesis, Structure, and Magnetism

“…Thus, the smooth production of organic carbonate by the addition reaction of epoxide and CO 2 is the outcome of the synergistic effect of catalyst and cocatalyst TBAB. 71 The cocatalyst screening was further optimized by using various inorganic salts such as sodium chloride (NaCl), potassium iodide (KI), and potassium bromide (KBr) and organic salts like TBAI (tetrabutylammonium iodide) and TBAC (tetrabutylammonium chloride) in this reaction (Table 1, entries 6−10). It was observed that our synthesized lanthanide-based catalysts in conjunction with TBAB have an utmost synergistic effect toward the organic carbonate synthetic reaction.…”