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Your search keyword '"Jiang, Zhong‐Tao"' showing total 506 results
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506 results on '"Jiang, Zhong‐Tao"'

16. Rhodium‐Catalyzed Enantio‐ and Regioselective Allylation of Indoles with gem‐Difluorinated Cyclopropanes.

Author

Yang, Hui, Zeng, Yaxin, Song, Xiangyu, Che, Lin, Jiang, Zhong‐Tao, Lu, Gang, and Xia, Ying

Subjects
ALLYLATION, INDOLE compounds, RHODIUM, FUNCTIONAL groups, CATALYSIS, INDOLE
Abstract

The use of gem‐difluorinated cyclopropanes (gem‐DFCPs) as fluoroallyl surrogates under transition‐metal catalysis has drawn considerable attention recently but such reactions are restricted to producing achiral or racemic mono‐fluoroalkenes. Herein, we report the first enantioselective allylation of indoles under rhodium catalysis with gem‐DFCPs. This reaction shows exceptional branched regioselectivity towards rhodium catalysis with gem‐DFCPs, which provides an efficient route to enantioenriched fluoroallylated indoles with wide substrate scope and good functional group tolerance. [ABSTRACT FROM AUTHOR]

Published
2024
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17. DFT + U investigation on high pressure properties of monoclinic CuO.

Author

Jaf, Zainab N., Miran, Hussein A., Rahman, M. Mahbubur, Amri, Amun, and Jiang, Zhong-Tao

Subjects
CONDUCTION bands, COPPER oxide, ELECTRIC conductivity, ENERGY dissipation, DENSITY functional theory, PRESSURE, BAND gaps
Abstract

This contribution demonstrates density functional theory calculations on the optoelectronic properties of monoclinic CuO under high pressures up to 15 GPa. In this account, the experimentally measured indirect band gap energy value of 1.41 eV has theoretically been predicted by tuning the Hubbard parameter (U) values for the partial electronic states. The values of the Hubbard parameter correspond to UCu-3d = 8 eV and UO-2p = 4.5 eV. The electronic and optical characteristics were examined under applied pressure and the results reveal development in the band gap values with increasing pressure from 1.41 to 2.01 eV. Total and projected density of states for the adopted pressures have been provided and displayed that the major contribution in the valance and conduction bands comes from O-2p and Cu-3d electronic states, respectively. The plotted reflectivity data suggest high optical reflectivity magnitudes relatively in the ultraviolet area. The investigated systems under variant pressures manifest rather an excellent absorption coefficient in the ultraviolet area, pushing them to be employed in solar cell technologies. Our analyzed results of the wavelength-dependent electrical conductivity of the investigated materials confirm the absorptivity behavior in the ultraviolet and small part of visible region of electromagnetic waves (EMW). Finally and most importantly, our obtained results of loss functions for the entire surveyed systems reveal a slight energy loss in a range of EMW, including ultraviolet and visible regions. [ABSTRACT FROM AUTHOR]

Published
2024
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24. Influence of the variation in the Hubbard parameter (U) on activation energies of CeO2-catalysed reactions

Author

Miran, Hussein A., Altarawneh, Mohammednoor, Jaf, Zainab N., Rahman, M. Mahbubur, Almatarneh, Mansour H., and Jiang, Zhong-Tao

Subjects
Thermodynamics, Activation energy, Cerium, Specific gravity, Acetylene, Density functionals, Hydrogenation, Physics
Abstract

Accurate description of thermodynamic, structural, and electronic properties for bulk and surfaces of ceria (CeO2) necessitates the inclusion of the Hubbard parameter (U) in the density functional theory (DFT) calculations to precisely account for the strongly correlated 4f electrons. Such treatment is a daunting task when attempting to draw a potential energy surface for CeO2-catalyzed reaction. This is due to the inconsistent change in thermo-kinetics parameters of the reaction in reference to the variation in the U values. As an illustrative example, we investigate herein the discrepancy in activation and reaction energies for steps underlying the partial and full hydrogenation of acetylene over the Ce[O.sub.2](111) surface. Overall, we find that both activation and reaction energies positively correlate with the increase in the U value. In addition to benchmarking against more accurate theoretical methodologies, we suggest that U values are better optimized against kinetics modelling of experimentally observed profiles of products from the catalytic-assisted system of reactions. Key words: ceria, DFT + U, reaction barriers, hydrogenation of acetylene, catalysts, transition state, Hubbard parameter (U). Une description precise des proprietes thermodynamiques, structurelles et electroniques de volume et de surface de l'oxyde de cerium (CeO2) requiert l'inclusion du parametre de Hubbard (U) dans le cadre d'un calcul en theorie de la fonctionnelle de densite (TFD), afin de tenir compte de facon precise des electrons 4f fortement correles. Un tel calcul est un defi important lorsqu'on tente d'obtenir la surface d'energie potentielle pour une reaction catalysee par Ce[O.sub.2]. Ceci est du au changement incoherent dans les parametres de reaction face a la variation de la valeur de U. Comme exemple illustratif, nous examinons ici le desaccord entre les energies d'activation et de reaction dans les etapes sous-jacentes a l'hydrogenation partielle et complete de l'acetylene sur une surface (111) de Ce[O.sub.2]. En resume, nous trouvons que ces deux energies sont correlees positivement avec l'augmentation de U. De plus, comme reference face a des methodes theoriques plus precises, nous suggerons d'optimiser les valeurs de U selon la modelisation cinetique des profils experimentaux de produits de reactions assistees par catalyse. [Traduit par la Redaction] Mots-cles : oxyde de cerium, hydrogenation, barriere de reaction, TFD, catalyse., 1. Introduction Cerium oxide (CeO2, ceria) and materials based on it are essential in many strategic catalytic industrial applications [1-3]. As oxygen-storage ingredients [4], they are utilized in three-way catalysts [...]

Published
2020
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