Search

Your search keyword '"Cheng, Qigan"' showing total 13 results
Start Over Author "Cheng, Qigan"
13 results on '"Cheng, Qigan"'

2. Two Manganese Metalloporphyrin Frameworks Constructed from a Custom-Designed Porphyrin Ligand Exhibiting Selective Uptake of CO2 over CH4 and Catalytic Activity for CO2 Fixation

Author

Magnuson, Zachary L., primary, Cheng, Qigan, additional, Zhang, Weijie, additional, Chen, Yu-Sheng, additional, Wojtas, Lukasz, additional, Nafady, Ayman, additional, Al-Enizi, Abdullah M., additional, Larsen, Randy W., additional, Zhang, X. Peter, additional, and Ma, Shengqian, additional

Published
2021
Full Text
View/download PDF

6. Two Manganese Metalloporphyrin Frameworks Constructed from a Custom-Designed Porphyrin Ligand Exhibiting Selective Uptake of CO2over CH4and Catalytic Activity for CO2Fixation

Author

Magnuson, Zachary L., Cheng, Qigan, Zhang, Weijie, Chen, Yu-Sheng, Wojtas, Lukasz, Nafady, Ayman, Al-Enizi, Abdullah M., Larsen, Randy W., Zhang, X. Peter, and Ma, Shengqian

Abstract

In this work, two new metal-metalloporphyrin frameworks (MMPFs), namely, MMPF-12 and MMPF-13, having unique structural formulas as [Mn24O78(Mn-dcdbp)12] and [Mn8.65(dcdbp)8](DMF)14(H2O)8, respectively, were synthesized via the reaction of the custom-designed porphyrin ligand 5,15-bis(3,5-dicarboxyphenyl)-10,20-bis(2,6-dibromophenyl) porphyrin (dcdbp) and hydrated manganese nitrate under solvothermal conditions. Single-crystal X-ray diffraction analysis reveals three-dimensional porous structures with MMPF-12 exhibiting nearly complete metalation of the ligand, whereas MMPF-13, unusually, contains only a small fraction of metalated porphyrin. Gas sorption studies attest to a permanent porosity together with selective adsorption of CO2over CH4. Additionally, both MMPFs catalyzed CO2cycloaddition of electronically and sterically substituted epoxide substrates, thereby providing access to important products under mild conditions. Results also showed that the ligand-metalated MMPF-12, containing trimer Mn clusters, has a higher catalytic activity than its congener MMPF-13, which has only dimer clusters. Thus, Mn clusters likely play an important role in both the structure of the MMPFs and their activity toward the transformation of CO2, with the enhanced catalytic activity being ascribed to the conserved porous structure.

Published
2021
Full Text
View/download PDF

7. Next‐Generation D2‐Symmetric Chiral Porphyrins for Cobalt(II)‐Based Metalloradical Catalysis: Catalyst Engineering by Distal Bridging.

Author

Hu, Yang, Lang, Kai, Tao, Jingran, Marshall, McKenzie K., Cheng, Qigan, Cui, Xin, Wojtas, Lukasz, and Zhang, X. Peter

Subjects
ENANTIOSELECTIVE catalysis, CATALYSTS, HYDROGEN bonding, AZIRIDINATION, CATALYTIC activity
Abstract

Novel D2‐symmetric chiral amidoporphyrins with alkyl bridges across two chiral amide units on both sides of the porphyrin plane (designated "HuPhyrin") have been effectively constructed in a modular fashion to permit variation of the bridge length. The CoII complexes of HuPhyrin, [Co(HuPhyrin)], represent new‐generation metalloradical catalysts where the metal‐centered d‐radical is situated inside a cavity‐like ligand with a more rigid chiral environment and enhanced hydrogen‐bonding capability. As demonstrated with cyclopropanation and aziridination as model reactions, the bridged [Co(HuPhyrin)] functions notably different from the open catalysts, exhibiting significant enhancement in both reactivity and stereoselectivity. Furthermore, the length of the distal alkyl bridge can have a remarkable influence on the catalytic properties. Building bridges: Novel D2‐symmetric chiral amidoporphyrins with alkyl bridges across two chiral amide units on both sides of the porphyrin plane have been effectively constructed in a modular fashion. The length of the distal bridge can significantly influence the reactivity and stereoselectivity of CoII‐based metalloradical catalysis. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
View/download PDF

12. Next-Generation D 2 -Symmetric Chiral Porphyrins for Cobalt(II)-Based Metalloradical Catalysis: Catalyst Engineering by Distal Bridging.

Author

Hu Y, Lang K, Tao J, Marshall MK, Cheng Q, Cui X, Wojtas L, and Zhang XP

Abstract

Novel D 2 -symmetric chiral amidoporphyrins with alkyl bridges across two chiral amide units on both sides of the porphyrin plane (designated "HuPhyrin") have been effectively constructed in a modular fashion to permit variation of the bridge length. The Co II complexes of HuPhyrin, [Co(HuPhyrin)], represent new-generation metalloradical catalysts where the metal-centered d-radical is situated inside a cavity-like ligand with a more rigid chiral environment and enhanced hydrogen-bonding capability. As demonstrated with cyclopropanation and aziridination as model reactions, the bridged [Co(HuPhyrin)] functions notably different from the open catalysts, exhibiting significant enhancement in both reactivity and stereoselectivity. Furthermore, the length of the distal alkyl bridge can have a remarkable influence on the catalytic properties., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Published
2019
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results