Heterometallic YbCo–Organic Framework for Efficiently Catalyzing Cycloaddition of CO₂ with Epoxides and Knoevenagel Condensation

Abstract

Due to the excellent catalytic performance of Co-MOFs and Ln-MOFs on the chemical fixation of CO2, the self-assembly of microporous heterometallic compounds with the aid of designed functional ligands is carried out in our group. Herein, the solvothermal self-assembly of Co2+, Yb3+, and 2,6-bis(2,4-dicarboxylphenyl)-4-(4-carboxylphenyl)pyridine (H5BDCP) generated a rarely reported {CoYb} n -chain-based framework of {[CoYb(BDCP)(H2O)]·3DMF·3H2O} n (NUC-70) with quasi-nanoporous channels (aperture ca. 11.4 Å) shaped by six rows of {CoYb(CO2)5(H2O)} n nodes. To the best of our knowledge, this is a rare 3d-4f heterometallic chain of {CoYb(CO2)5(H2O)} n with a staggered arrangement of Co2+ and Yb3+. After removing the associated water molecules, NUC-70a possesses the excellent characteristics of a large specific surface area, unsaturated open metal sites of Co2+ and Yb3+ as Lewis acid sites, and high heat/water-resistant physicochemical properties. Catalytic experiments showed that NUC-70a possessed a high catalytic activity on the cycloaddition reactions of epoxides with CO2 under mild conditions. Furthermore, the experiments performed confirmed that the Knoevenagel condensation reactions of aldehydes and malononitrile could be efficiently catalyzed by NUC-70a. This work illustrates that characteristic ligand design plays a key role in the self-assembly of MOFs with specific functions.

Robust {Cd4}-Organic Framework for Efficiently Catalyzing CO2 Cycloaddition and Knoevenagel Condensation

“…Furthermore, the adsorption capacities for CO 2 are 93.1 cm 3 g –1 (273 K) and 57.8 cm 3 g –1 (298 K) (Figure S8). In addition, the adsorption enthalpy ( Q st ) at zero loading obtained by the virial method is 16.9 kJ mol –1 (Figure S9), exhibiting that the bonding affinity between CO 2 molecules and the host framework is moderate and analogous to most of the documented MOFs. − …”

“…Herein, we report a highly robust {Cd 4 }-based nanoporous cadmium­(II)–organic framework of {(Me 2 NH 2 ) 5 [Cd 4 (BDCP) 2 (μ 3 -OH) 2 (CH 3 CO 2 )­(H 2 O) 2 ]·3DMF·2H 2 O} n ( NUC-67 ). In terms of its satisfactory features of high CO 2 adsorption capacity, worm-shaped nanoscale pore structure, and generous coexistent Lewis acid–base sites of exposed Cd II sites, N pyridine atoms, μ 3 -OH, and CH 3 CO 2 – , the catalytic performance was checked for the cycloaddition of CO 2 with epoxides and Knoevenagel condensation, both of which can be catalyzed by Lewis acid and/or base sites of activated MOFs according to the literature. − …”

θ-[Mo8O26]4−-based multifunctional hybrid material for high catalytic performance on the cycloaddition of CO2, esterification and knoevenagel condensation

“…For small molecule benzaldehydes, such as p-fluorobenzaldehyde, p-bromobenzaldehyde and p-nitrobenzaldehyde, the conversion rate could be regarded as full conversion (entries 2-4), which could be because the strong electron-withdrawing ability of substitutes can effectively reduce the electronic density of the aldehyde group, in which the carbon atom is easier to attack by nucleophilic groups. [71][72][73] Conversely, aldehydes with electron-donating substitutes, such as -CH 3 and -OCH 3 , offered a slightly reduced yield (entries 5-9). In addition, steric hindrance also has a great negative effect on the conversion of reactants, resulting in a significant decrease in the final yield, especially for macromolecule 4-(methyl 4-carboxylphenoxy)benzadehude.…”

Robust Fluorine-Functionalized {Ln5}-Organic Frameworks for Excellent Catalytic Performance on Cycloaddition of CO2 with Epoxides and Knoevenagel Condensation

“…9,10 Among all publicized MOFs, their performance proved that materials with polymetallic clusters as basic units not only had the excellent optical, electrical, magnetic, and catalytic properties but also owned the higher chemical stability. 11,12 In recent years, MOFs with lanthanide-based metal-carboxylate polynuclear clusters as secondary building units (SBUs) have been at the forefront of significant progress. This is due to that the higher charge as well as the larger radius of Ln 3+ can better match the relatively hard carboxylate oxygen atoms, which render the generated MOFs have remarkably improved chemical stability.…”

“…Microporous metal–organic frameworks (MOFs) are a unique type of novel functional materials with high specific surface area, large porosity, and various adjustable uniform-rich active sites. MOFs have attracted more and more attention both from the academic and the industry because of widespread applications in the field of organic catalysis, , inductive energy storage, , gas separation-purification, , optic-chemical sensing, , proton conductivity, and environmental purification. , Among all publicized MOFs, their performance proved that materials with polymetallic clusters as basic units not only had the excellent optical, electrical, magnetic, and catalytic properties but also owned the higher chemical stability. , In recent years, MOFs with lanthanide-based metal-carboxylate polynuclear clusters as secondary building units (SBUs) have been at the forefront of significant progress. This is due to that the higher charge as well as the larger radius of Ln 3+ can better match the relatively hard carboxylate oxygen atoms, which render the generated MOFs have remarkably improved chemical stability. , However, the construction principle of porous cluster-based structures are still not been controlled artificially due to that the hard-sphere behavior of Ln 3+ makes it difficult to guide the dimensionality and directionality of metal–organic elongation growth, usually leading to chain-like or interspersed structures.…”