Theoretical Study on the Catalytic CO₂ Hydrogenation over the MOF-808-Encapsulated Single-Atom Metal Catalysts

The search for new catalytic agents for reducing excess CO2 in the atmosphere is a challenging but essential task. Due to the well-defined porous structures and unique physicochemical properties, metal–organic frameworks (MOFs) have been regarded as one of the promising materials in the catalytic conversion of CO2 into valuable platform chemicals. In particular, introducing the second metal (M) atom to form the MII–O–Zr4+ single-atom metal sites on the Zr nodes of MOF-808 would further greatly improve the catalytic performance. Herein, CO2 hydrogenation reaction mechanisms and kinetics over a series of MOF-808-encapsulated single-atom metal catalysts, i.e., MII–MOF-808 (MII = CuII, FeII, PtII, NiII, and PdII), were systematically studied using density functional theory calculations. First, it has been found that the stability for the encapsulation of a divalent metal ion follows the trend of PtII > NiII > PdII > CuII > FeII, while they all possess moderate anchoring stability on the MOF-808 with the Gibbs replacement energies ranging from −233.7 to −310.3 kcal/mol. Two plausible CO2 hydrogenation pathways on CuII–MOF-808 catalysts, i.e., formate and carboxyl routes, were studied. The formate route is more favorable, in which the H2COOH*-to-H2CO* step is kinetically the most relevant step over CuII–MOF-808. Using the energetic span model, the relative turnover frequencies of CO2 hydrogenation to various C1 products over MII–MOF-808 were calculated. The CuII–MOF-808 catalyst is found to be the most active catalyst among five MII–MOF-808 catalysts

Deformation of Nanoporous Carbons Induced By Multicomponent Adsorption: Insight from the SAFT-DFT Model

Deformation of nanoporous materials during gas adsorption has been attracting considerable attention due to various applications, including energy and gas storage, carbon capture, and separation. While most practical applications involve multicomponent mixtures, most experimental and theoretical works deal with single-component adsorption. Here, we study the specifics of adsorption-induced deformation during the displacement of methane by carbon dioxide from carbon nanopores, a process of paramount importance for secondary gas recovery and carbon sequestration in shale and coal formations. Density functional theory calculations augmented by the perturbed-chain statistical associating fluid theory (SAFT-DFT) and grand canonical Monte Carlo (GCMC) simulations are employed to model the adsorption of CH4–CO2 mixtures on carbon slit nanopores of various sizes. We found a nonmonotonic behavior of adsorption deformation with increasing pressure and varying mixture composition that is explained by the peculiarities of molecule packings confined in nanoscale pores. The SAFT-DFT method is shown to produce results in agreement with atomistic GCMC simulations at a fraction of the computational cost. The SAFT-DFT method can be extended to study the adsorption selectivity and deformation effects for complex mixtures, including hydrocarbons and CO2

Deformation of Nanoporous Carbons Induced By Multicomponent Adsorption: Insight from the SAFT-DFT Model

Deformation of nanoporous materials during gas adsorption has been attracting considerable attention due to various applications, including energy and gas storage, carbon capture, and separation. While most practical applications involve multicomponent mixtures, most experimental and theoretical works deal with single-component adsorption. Here, we study the specifics of adsorption-induced deformation during the displacement of methane by carbon dioxide from carbon nanopores, a process of paramount importance for secondary gas recovery and carbon sequestration in shale and coal formations. Density functional theory calculations augmented by the perturbed-chain statistical associating fluid theory (SAFT-DFT) and grand canonical Monte Carlo (GCMC) simulations are employed to model the adsorption of CH4–CO2 mixtures on carbon slit nanopores of various sizes. We found a nonmonotonic behavior of adsorption deformation with increasing pressure and varying mixture composition that is explained by the peculiarities of molecule packings confined in nanoscale pores. The SAFT-DFT method is shown to produce results in agreement with atomistic GCMC simulations at a fraction of the computational cost. The SAFT-DFT method can be extended to study the adsorption selectivity and deformation effects for complex mixtures, including hydrocarbons and CO2

Unexpected Cyclization Product Discovery from the Photoinduced Bioconjugation Chemistry between Tetrazole and Amine

Bioconjugation chemistry has emerged as a powerful tool for the modification of diverse biomolecules under mild conditions. Tetrazole, initially proposed as a bioorthogonal photoclick handle for 1,3-dipolar cyclization with alkenes, was later demonstrated to possess broader photoreactivity with carboxylic acids, serving as a versatile bioconjugation and photoaffinity labeling probe. In this study, we unexpectedly discovered and validated the photoreactivity between tetrazole and primary amine to afford a new 1,2,4-triazole cyclization product. Given the significance of functionalized N-heterocycles in medicinal chemistry, we successfully harnessed the serendipitously discovered reaction to synthesize both pharmacologically relevant DNA-encoded chemical libraries (DELs) and small molecule compounds bearing 1,2,4-triazole scaffolds. Furthermore, the mild reaction conditions and stable 1,2,4-triazole linkage found broad application in photoinduced bioconjugation scenarios, spanning from intramolecular peptide macrocyclization and templated DNA reaction cross-linking to intermolecular photoaffinity labeling of proteins. Triazole cross-linking products on lysine side chains were identified in tetrazole-labeled proteins, refining the comprehensive understanding of the photo-cross-linking profiles of tetrazole-based probes. Altogether, this tetrazole-amine bioconjugation expands the current bioconjugation toolbox and creates new possibilities at the interface of medicinal chemistry and chemical biology