Rational Construction of an Exceptionally Stable MOF Catalyst with Metal‐Adeninate Vertices toward CO₂ Cycloaddition under Mild and Cocatalyst‐Free Conditions

Abstract

CO2 is considered as the primary greenhouse gas, resulting in a series of serious environmental problems that affect people's life and health. Carbon capture and sequestration has been implemented as one of the most appealing pathways to control and use CO2. Here, we rationally integrate various functional sites within the confined nanospace of a microporous metal–organic framework (MOF) material, which is constructed by mixed‐ligand strategy based on metal‐adeninate vertices. It not only exhibits excellent stability but also can efficiently transform CO2 and epoxides to cyclic carbonates under mild and cocatalyst‐free conditions. Additionally, this catalyst shows extraordinary recyclability for the CO2 cycloaddition reaction.

Nanochannel-based {BaZn}–organic framework for catalytic activity on the cycloaddition reaction of epoxides with CO2 and deacetalization-Knoevenagel condensation

“…As for the component and microstructure connection mode, the asymmetric unit consists of a half crystallographically independent Ba(II) ion, a half Zn(II) ion, a half associated water molecules, a half TDP 6− ligand, and two [(CH 3 ) 2 NH 2 ] + ions, which result from thermal decomposition of the DMF molecules and balance the negative charge of the framework 46,47,50 (Fig. 1a).…”

Design and Construction of a Porous Heterometallic Organic Framework Based on Cu6I6 Clusters and One-Dimensional TbIII Chains: Syntheses, Crystal Structure, and Various Properties

“…However, the corresponding catalytic yields of these aimed cyclic carbonates gradually decreased to 96.8%, 93.2%, 86.5%, 81.9%, and 53.7% for styrene oxide (entry 5), 1,2-epoxy-3-allyloxypropane (entry 6), benzyl phenylglycidyl ether (entry 7), tert -butyl glycidyl ether (entry 8), and cyclohexene oxide (entry 9), respectively. The different catalytic performances for different epoxides may be probably ascribed to the hindrance effect and different electronic effects of functional groups. − …”

Dynamic Metal–Iodide Bonds in a Tetracoordinated Cadmium-Based Metal–Organic Framework Boosting Efficient CO2 Cycloaddition under Solvent- and Cocatalyst-Free Conditions

“…Metal–organic frameworks (MOFs), an outstanding class of crystalline porous materials, have emerged as excellent candidates for heterogeneous CO 2 conversion, due to their tunable pores for CO 2 capture and substrate diffusion as well as the ultrahigh specific surface areas and abundant active sites for substrate activation. − To avoid the structural damage of MOFs from the extreme reaction environment, cocatalysts (such as nucleophilic tetrabutylammonium bromide, TBAB) are normally added to aid the ring-opening of epoxides and to ensure that the reaction is performed under milder conditions. − The addition can undoubtedly cause additional waste, catalyst leaching, and environmental pollution, meanwhile increasing the actual difficulty of product separation. , Therefore, the current research mainly focuses on two types of cocatalyst-free MOF systems: one is the Lewis acid–base bifunctional MOF catalyst, where CO 2 is polarized by the Lewis base sites to attack the β-C of the Lewis acid-activated epoxide to finish ring-opening; − another is the TBAB-like active species encapsulated in or immobilized on MOF catalysts to directly promote ring-opening via the two-component synergistic catalysis. , Recently, UMCM-1-NH 2 , subtly assembled by Babu et al, exhibits exposed metal sites and amino Lewis base sites for efficient cycloaddition of CO 2 with epoxides under cocatalyst-free conditions . Liang et al combined Zr-MOF with imidazole ionic liquids by the postmodification method to generate (I – ) MeIM-UIO-66, and the free I – as a strong nucleophile causes the epoxide ring-opening, achieving high catalytic efficiency of cycloaddition without any cocatalyst .…”