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24 results on '"Yao, Wenzhi"'

6. Cobalt(I) Pincer Complexes as Catalysts for CO2Hydrogenation to Formate

Author

Yao, Wenzhi, Olajide, Gbolagade, Boudreaux, Chance M., Wysocki, Megan M., Ahmed, Md. Kausar, Qu, Fengrui, Szilvási, Tibor, and Papish, Elizabeth T.

Abstract

Carbon dioxide hydrogenation with a base to generate formate salts can provide a means of storing hydrogen in an energy-dense solid. However, this application requires catalytic CO2hydrogenation, which would ideally use an earth-abundant metal catalyst. In this article, six new (CNC)CoIL2pincer complexes were synthesized and fully characterized including single-crystal X-ray diffraction analysis on four new complexes. These complexes contain an imidazole-based (1R) N-heterocyclic carbene (NHC) ring or a benzimidazole-based NHC ring (2R) in the CNC pincer. The R group is parato N on the pyridine ring and has been varied from electron-withdrawing (CF3) to donating (Me, OMe) substituents. The L-type ligands have included CO and phosphine ligands (in PPh32and PMe32). Thus, two known Co complexes (1, 1OMe) and six new complexes (1Me, 1CF3, 2, 2OMe, PPh32, and PMe32) were studied for the CO2hydrogenation reaction. In general, the unsubstituted CNC pincer complexes bearing two carbonyl ligands led to the highest activity. The best catalyst, 2, remains active for over 16 h and produces a turnover number of 39,800 with 20 bar of 1:1 CO2/H2mixture at 60 °C. A computational study of the mechanism of CO2hydrogenation is also reported.

Published
2024
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22. Density Functional Theory Study on the Enhancement Mechanism of the Photocatalytic Properties of the g-C 3 N 4 /BiOBr(001) Heterostructure.

Author

Yao W, Li D, Wei S, Liu X, Liu X, and Wang W

Abstract

The van der Waals heterostructures fabricated in two semiconductors are currently attracting considerable attention in various research fields. Our study uses density functional theory calculations within the Heyd-Scuseria-Ernzerhof hybrid functional to analyze the geometric structure and electronic structure of the g-C 3 N 4 /BiOBr(001) heterojunction in order to gain a better understanding of its photocatalytic properties. The calculated band alignments show that g-C 3 N 4 /BiOBr can function as a type-II heterojunction. In this heterojunction, the electrons and holes can effectively be separated at the interface. Moreover, we find that the electronic structure and band alignment of g-C 3 N 4 /BiOBr(001) can be tuned using external electric fields. It is also noteworthy that the optical absorption peak in the visible region is enhanced under the action of the electric field. The electric field may even improve the optical properties of the g-C 3 N 4 /BiOBr(001) heterostructure. Given the results of our calculations, it seems that g-C 3 N 4 /BiOBr(001) may be significantly superior to visible light photocatalysis., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Published
2022
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23. Frustrated Lewis Acid/Brønsted Base Catalysts for Direct Enantioselective α-Amination of Carbonyl Compounds.

Author

Shang M, Wang X, Koo SM, Youn J, Chan JZ, Yao W, Hastings BT, and Wasa M

Abstract

A method for enantioselective direct α-amination reaction catalyzed by a sterically "frustrated" Lewis acid/Brønsted base complex is disclosed. Cooperative functioning of the Lewis acid and Brønsted base components gives rise to in situ enolate generation from monocarbonyl compounds. Subsequent reaction with hydrogen-bond activated dialkyl azodicarboxylates delivers α-aminocarbonyl compounds in high enantiomeric purity.

Published
2017
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24. Direct Mannich-Type Reactions Promoted by Frustrated Lewis Acid/Brønsted Base Catalysts.

Author

Chan JZ, Yao W, Hastings BT, Lok CK, and Wasa M

Abstract

Direct Mannich-type reactions that afford both α- and β-amino esters by the reaction of a broad range of carbonyl compounds and aldimines are disclosed. The transformation is promoted by a sterically frustrated Lewis acid/Brønsted base pair, which is proposed to operate cooperatively: Within the catalyst complex, an enolate is generated that then reacts with a hydrogen-bond-activated imine. Noncovalent interactions between reactants and the catalyst provide selectivity and new opportunities for future catalyst design., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Published
2016
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