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2,607 results on '"Tung, Chen‐Ho"'

110. γ-Cyclodextrin-Directed Enantioselective Photocyclodimerization of Methyl 3-Methoxyl-2-naphthoate

Author

Luo, Lin, Liao, Gui-Hong, Wu, Xiao-Ling, Lei, Lei, Tung, Chen-Ho, and Wu, Li-Zhu

Abstract

Irradiation of methyl 3-methoxyl-2-naphthoate (2,3-NA) in methanol solution with light λ > 280 nm produces anti-head-to-head cubane-like photocyclodimer 1and [4+4] intermediate 2, which is, to the best of our knowledge, the first incidence of directly obtaining the intermediate in photocyclodimerization of naphthalene analogues. X-ray crystal structural analysis has realized the chirality of 1, and the optically pure enantiomers 1aand 1bhave been achieved by HPLC resolution. To understand the fundamental photocyclodimerization of naphthalene analogues mediated by native γ-CD, the neutral 2,3-NAwas selected as a typical reactant in this work. UV−vis, fluorescence, and 1H NMR analysis reveal that γ-CD can encapsulate 2,3-NAto make a stable 2:1 inclusion complex 2,3-NA@γ-CD both in aqueous solution and in the solid state. Irradiation of 2,3-NA@γ-CD results in photocyclodimerization with remarkable selectivity and efficiency, whereas no photocyclodimers could be detected in host-free aqueous solution and the neat solids. More importantly, the use of native γ-CD as a chiral reaction vessel turns out to be an effective and versatile strategy for the enantioselective photocyclodimerization of 2,3-NA. The ee values of 48% in aqueous solution and up to 34% in the solid state for anti-head-to-head photocyclodimer 1have been achieved upon irradiation of the inclusion complex of 2,3-NA@γ-CD under ambient temperature and pressure. All of the observations indicate that native γ-CD with hydrophobic interaction only is capable of regulating the orientation of naphthalene analogue 2,3-NAwithin the cavity of γ-CD, and thereby leading to the highest ee value of 48% obtained so far for the photocyclodimerization with native γ-CD in solution.

Published
2024
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113. Aliphatic C–H arylation with heteroarenes without photocatalysts.

Author

Ci, Rui-Nan, Qiao, Jia, Gan, Qi-Chao, Chen, Bin, Tung, Chen-Ho, and Wu, Li-Zhu

Subjects
HETEROARENES, ARYLATION, METAL catalysts, ALKYL radicals, PRECIOUS metals, PHOTOCATALYSTS, PHOTOCATALYTIC oxidation
Abstract

Direct sp3 C–H arylation with heteroarenes is a straightforward approach for accessing valuable heteroarene-containing molecules. Unlike the established approaches that generally require precious metal catalysts, directing groups, stoichiometric strong oxidants and high temperatures, we report herein a scalable and mild strategy for aliphatic C–H arylation with heteroarenes under photocatalyst-free and strong oxidant-free conditions. This photochemistry features a broad substrate scope, good to excellent yields, and extremely mild conditions. Spectroscopic studies reveal that protonated heteroarenes have light-absorbing ability to initiate alkyl radical formation from aliphatic C–H bonds under aerobic visible light irradiation. [ABSTRACT FROM AUTHOR]

Published
2023
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114. Dynamic and transformable Cu12 cluster-based C-H···π-stacked porous supramolecular frameworks.

Author

Zhang, Chengkai, Wang, Zhi, Si, Wei-Dan, Chu, Hongxu, Zhou, Lan, Li, Tong, Huang, Xian-Qiang, Gao, Zhi-Yong, Azam, Mohammad, Tung, Chen-Ho, Cui, Ping, and Sun, Di

Subjects
STRUCTURAL dynamics, STRUCTURAL stability, SUPRAMOLECULAR chemistry, RESEARCH personnel, AQUEOUS solutions, IODINE
Abstract

The assembly of cluster-based π-stacked porous supramolecular frameworks presents daunting challenges, including the design of suitable cluster building units, control of the sufficient C-H···π interactions, trade-off between structural dynamics and stability as well as understanding the resulting collective properties. Herein, we report a cluster-based C-H···π interaction-stacked porous supramolecular framework, namely, Cu12a-π, consisting of Cu12 nanocluster as a 6-connected node, which is further propagated to a dynamic porous supramolecular frameworks via dense intralayer C-H···π interactions, yielding permanent porosity. In addition, Cu12a-π can be transformed into cluster-based nonporous adaptive crystals (Cu12b-NACs) via ligand-exchange following a dissociation-reassembly mechanism. Moreover, Cu12a-π can efficiently remove 97.2% of iodine from saturated iodine aqueous solutions with a high uptake capacity of 2.96 g·g−1. These prospective results positioned at cluster-based porous supramolecular framework and enlighten follow-up researchers to design and synthesize such materials with better performance. The assembly of cluster-based π-stacked porous supramolecular frameworks presents daunting challenges. Here, the authors report a dynamic and transformable supramolecular framework based on Cu12 cluster and C-H···π-stacking with permanent porosity [ABSTRACT FROM AUTHOR]

Published
2023
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115. Visible-light-driven [3 + 2] cyclization of phenols with indoles and olefins using recyclable Ag3PO4 nanoparticles.

Author

Guo, Lirong, Chen, Guanjie, Li, Haibin, Tung, Chen-Ho, and Wang, Yifeng

Subjects
INDOLE compounds, PHENOLS, PHENOL, ALKENES, RADICAL cations, SILVER phosphates
Abstract

Ag3PO4 promotes the oxidative [3 + 2] annulation of phenols with styrenes and indoles for the syntheses of 2,3-dihydrobenzofurans and benzofuroindolines under visible-light irradiation. The approach is additive-free, mild, scalable, and, most importantly, Ag3PO4 recyclable. The mechanism involves the cross-coupling of stabilized phenol radical and styrene radical cation on the Ag3PO4 surfaces. [ABSTRACT FROM AUTHOR]

Published
2023
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116. In situ assembly of nickel-based ultrathin catalyst film for water oxidation.

Author

Wei, Xiang-Zhu, Liao, Fang-Jie, Xu, Xin, Ye, Chen, Tung, Chen-Ho, and Wu, Li-Zhu

Subjects
THIN films, OXIDATION of water, OXYGEN evolution reactions, OVERPOTENTIAL, NICKEL mining
Abstract

A nickel-based ultrathin catalyst film is assembled in situ from a solution of Ni(OAc)2 and a Schiff-base ligand L. The resulting ultrathin catalyst film shows a low overpotential of 330 mV, a steady current of 7 mA cm−2 for water oxidation over 10 h. [ABSTRACT FROM AUTHOR]

Published
2023
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117. Tracking an FeV(O) Intermediate for Water Oxidation in Water.

Author

Wei, Xiang‐Zhu, Ding, Tian‐Yu, Wang, Yang, Yang, Bing, Yang, Qing‐Qing, Ye, Shengfa, Tung, Chen‐Ho, and Wu, Li‐Zhu

Subjects
OXIDATION of water, CHEMICAL amplification, CATALYTIC oxidation, OXYGEN isotopes, RADIOLABELING
Abstract

High‐valent iron‐oxo species are appealing for conducting O−O bond formation for water oxidation reactions. However, their high reactivity poses a great challenge to the dissection of their chemical transformations. Herein, we introduce an electron‐rich and oxidation‐resistant ligand, 2‐[(2,2′‐bipyridin)‐6‐yl]propan‐2‐ol to stabilize such fleeting intermediates. Advanced spectroscopies and electrochemical studies demonstrate a high‐valent FeV(O) species formation in water. Combining kinetic and oxygen isotope labelling experiments and organic reactions indicates that the FeV(O) species is responsible for O−O bond formation via water nucleophilic attack under the real catalytic water oxidation conditions. [ABSTRACT FROM AUTHOR]

Published
2023
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137. Ag 22 Nanoclusters with Thermally Activated Delayed Fluorescence Protected by Ag/Cyanurate/Phosphine Metallamacrocyclic Monolayers through In‐Situ Ligand Transesterification

Author

Yuan, Zhi‐Rui, primary, Wang, Zhi, additional, Han, Bao‐Liang, additional, Zhang, Cheng‐Kai, additional, Zhang, Shan‐Shan, additional, Zhu, Zhen‐Yu, additional, Yu, Jiu‐Hong, additional, Li, Tian‐Duo, additional, Li, Ying‐Zhou, additional, Tung, Chen‐Ho, additional, and Sun, Di, additional

Published
2022
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150. Covalent organic framework and hydrogen-bonded organic framework for solar-driven photocatalysis.

Author

Qin, Wei-Kang, Tung, Chen-Ho, and Wu, Li-Zhu

Abstract

The newly emerging porous crystalline materials, covalent organic framework (COF) and hydrogen-bonded organic framework (HOF), are characterized by their large surface area, considerable structural diversity, and functional tailorability. Combining these properties, they are considered to have the potential for photocatalysis. This review summarizes their advantages and compatibility, particularly focusing on design strategies to overcome the existing issues of poor charge conductivity and deficient active sites. With representative examples of solar-driven hydrogen (H2) evolution and carbon dioxide (CO2) reduction, the exploration and expectation of such functional porous materials are presented. [ABSTRACT FROM AUTHOR]

Published
2023
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