Rational Design of a Zn^II MOF with Multiple Functional Sites for Highly Efficient Fixation of CO₂ under Mild Conditions: Combined Experimental and Theoretical Investigation

Abstract

The development of efficienth eterogeneous catalysts suitable for carbon capture and utilization(CCU) under mild conditions is ap romisingstep towards mitigating the growingc oncentration of CO 2 in the atmosphere.H erein, we report the constructiono fahydrogen-bonded 3D framework, {[Zn(hfipbba)(MA)]•3 DMF} n (hfipbba = 4,4'-(hexaflouroisopropylene)bis(benzoic acid)) (HbMOF1)u tilizingZ n II center,apartially fluorinated, long-chain dicarboxylate ligand (hfipbba), anda na mine-rich melamine (MA) coligand.I nterestingly,t he framework possesses two types of 1D channels decorated with CO 2-philic (ÀNH 2 and ÀCF 3) groups that promote the highly selectiveC O 2 adsorption by the framework,w hich was supported by computational simulations. Further,t he synergistic involvement of both Lewis acidic and basic sites exposedi nt he confined 1D channels along with high thermala nd chemical stabilityr endered HbMOF1 ag ood heterogeneousc atalyst for the highly efficient fixation of CO 2 in ar eaction with terminal/internal epoxidesa tm ild conditions (RT and 1bar CO 2). Moreover,i ndepth theoretical studies were carried out using periodic DFT to obtaint he relative energies for each stage involved in the catalytic reaction anda ni nsight mechanisticd etails of the reactioni sp resented. Overall,t his work represents ar are demonstrationo fr ational design of ap orousZ n II MOF incorporatingm ultiple functional sites suitable for highly efficient fixationo fCO 2 with terminal/internal epoxides at mild conditions supported by comprehensive theoretical studies.

Strategic design of a bifunctional Ag(i)-grafted NHC-MOF for efficient chemical fixation of CO2 from a dilute gas under ambient conditions

“…In this regard, MOFs have attracted tremendous interest owing to their modular nature which facilitates the introduction of CO 2philic and catalytically active sites for the simultaneous capture and utilization of carbon dioxide. [44][45][46][47][48][49][50][51][52] Among the various types of MOFs utilized for the chemical fixation of carbon dioxide, N-heterocyclic carbene (NHC)-based MOFs have gained special interest because the NHC sites can act as potential anchoring sites for catalytic metal ions and also provide CO 2 -philicity to the framework. [53][54][55][56] Here, the covalent linkage formed between the carbene site and Ag(I) will be beneficial in preventing the possible leaching of Ag(I) during the catalysis.…”

Chemical Fixation of CO2 Under Solvent and Co-Catalyst-free Conditions Using a Highly Porous Two-fold Interpenetrated Cu(II)-Metal–Organic Framework

“…Further, the catalytic activity of Cu­(II)-MOF was extended for cycloaddition of various epoxides under the optimized conditions of 80 °C, CO 2 pressure of 8 bar for 24 h. The results showed that catalytic conversion of epoxides with a longer alkyl chain length such as 1,2-epoxypropane, 1,2-epoxybutane, and 1,2-epoxyhexane were found to be reduced to 86, 82, and 48%, respectively, with an increase in the alkyl chain length, which is in line with the previously reported literature (Table , Figures S18–S20), − whereas allyl glycidyl ether and butyl glycidyl ether were found to undergo respectively 92 and 84% conversions to the corresponding cyclic carbonates, which can be attributed to the electron-withdrawing nature of the epoxides (Table , Figures S21 and S22). ,, It is worth mentioning that the Cu­(II)-MOF acts as a recyclable catalyst for conversion of CO 2 with ECH at relatively mild conditions (Table S4). − …”

Coordination Polymers from 2-Chloroterephthalate Linkers: Synthesis, Structural Diversity, and Catalytic CO2 Fixation

“…In contrast, control experiments in the absence of catalyst or using CltaH 2 or ZnCl 2 as catalysts led to only 13, 15, and 18% product yields, respectively (entries 14–16). Although a clear relationship between the activity and catalyst structure cannot be clearly demonstrated, a superior activity of the compound 4 may eventually be explained by the presence of open metal sites and OH – groups, along with a Lewis acidic character of zinc­(II) centers. − …”

“…Following a literature background for related coupling reactions between epoxides and carbon dioxide catalyzed by coordination polymers, − ,, a possible mechanism for the present 4 / n -Bu 4 NBr catalytic system was proposed (Scheme ). In the step I, there is an activation of an epoxide substrate by the Lewis acidic site (Zn 2+ ) forming an intermediate.…”

“…With regard to catalysis, various CP-catalyzed processes that utilize carbon dioxide as an important C1 feedstock have been getting an impetus in recent years. − This is primarily explained by the interest in mitigating the emissions of CO 2 as a major greenhouse gas as well as by its high abundance as a C1 feedstock. In particular, the coupling reactions between CO 2 and epoxides to generate cyclic carbonates are very attractive with implications toward reducing carbon dioxide emissions and producing value-added products. − Although various transition-metal-based catalytic systems were applied in epoxide coupling with CO 2 , there is a considerable interest in the development of versatile and recyclable CP-based catalytic systems for this type of process. − …”