Author
Haolin Yin
Bio: Haolin Yin is an academic researcher from University of Pennsylvania. The author has contributed to research in topics: Aryl & Cerium. The author has an hindex of 16, co-authored 22 publications receiving 1546 citations.
Topics: Aryl, Cerium, Coordination complex, Umpolung, Homolysis
Papers
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887 citations
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145 citations
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TL;DR: Surprisingly, comparison of an extensive array of ligands revealed that under the basic reaction conditions the resultant heterobimetallic Pd–NiXantphos catalyst system outperformed all the other mono- and bidentate ligands in a deprotonative cross-coupling process (DCCP) with aryl chlorides.
Abstract: Although the past 15 years have witnessed the development of sterically bulky and electron-rich alkylphosphine ligands for palladium-catalyzed cross-couplings with aryl chlorides, examples of palladium catalysts based on either triarylphosphine or bidentate phosphine ligands for efficient room temperature cross-coupling reactions with unactivated aryl chlorides are rare. Herein we report a palladium catalyst based on NiXantphos, a deprotonatable chelating aryldiphosphine ligand, to oxidatively add unactivated aryl chlorides at room temperature. Surprisingly, comparison of an extensive array of ligands revealed that under the basic reaction conditions the resultant heterobimetallic Pd–NiXantphos catalyst system outperformed all the other mono- and bidentate ligands in a deprotonative cross-coupling process (DCCP) with aryl chlorides. The DCCP with aryl chlorides affords a variety of triarylmethane products, a class of compounds with various applications and interesting biological activity. Additionally, th...
128 citations
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TL;DR: The strongly reducing metalloradical character of 1, 1-(i)Pr, and 1-Cy in their (2)A1 excited states afforded photochemical halogen atom abstraction reactions from sp(3) and sp(2) C-X (X = Cl, Br, I) bonds for the first time with a lanthanide cation.
Abstract: Luminescent Ce(III) complexes, Ce[N(SiMe3)2]3 (1) and [(Me3Si)2NC(RN)2]Ce[N(SiMe3)2]2 (R = iPr, 1-iPr; R = Cy, 1-Cy), with C3v and C2v solution symmetries display absorptive 4f → 5d electronic transitions in the visible region. Emission bands are observed at 553, 518, and 523 nm for 1, 1-iPr, and 1-Cy with lifetimes of 24, 67, and 61 ns, respectively. Time-dependent density functional theory (TD-DFT) studies on 1 and 1-iPr revealed the 2A1 excited states corresponded to singly occupied 5dz2 orbitals. The strongly reducing metalloradical character of 1, 1-iPr, and 1-Cy in their 2A1 excited states afforded photochemical halogen atom abstraction reactions from sp3 and sp2 C–X (X = Cl, Br, I) bonds for the first time with a lanthanide cation. The dehalogenation reactions could be turned over with catalytic amounts of photosensitizers by coupling salt metathesis and reduction to the photopromoted atom abstraction reactions.
115 citations
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TL;DR: The photochemistry of the sterically congested complex 4 was demonstrated by C-C bond forming reaction between 4-fluoroiodobenzene and benzene through an outer sphere electron transfer pathway, which expands the capabilities of cerium photosensitizers beyond the previous results that demonstrated inner sphere halogen atom abstraction reactivity by 1-N.
Abstract: Two complete mixed-ligand series of luminescent Ce(III) complexes with the general formulas [(Me3Si)2NC(N(i)Pr)2]xCe(III)[N(SiMe3)2]3-x (x = 0, 1-N; x = 1, 2-N, x = 2, 3-N; x = 3, 4) and [(Me3Si)2NC(N(i)Pr)2]xCe(III)(OAr)3-x (x = 0, 1-OAr; x = 1, 2-OAr, x = 2, 3-OAr; x = 3, 4) were developed, featuring photoluminescence quantum yields up to 0.81(2) and lifetimes to 117(1) ns. Although the 4f → 5d absorptive transitions for these complexes were all found at ca. 420 nm, their emission bands exhibited large Stokes shifts with maxima occurring at 553 nm for 1-N, 518 nm for 2-N, 508 nm for 3-N, and 459 nm for 4, featuring yellow, lime-green, green, and blue light, respectively. Combined time-dependent density functional theory (TD-DFT) calculations and spectroscopic studies suggested that the long-lived (2)D excited states of these complexes corresponded to singly occupied 5dz(2) orbitals. The observed difference in the Stokes shifts was attributed to the relaxation of excited states through vibrational processes facilitated by the ligands. The photochemistry of the sterically congested complex 4 was demonstrated by C-C bond forming reaction between 4-fluoroiodobenzene and benzene through an outer sphere electron transfer pathway, which expands the capabilities of cerium photosensitizers beyond our previous results that demonstrated inner sphere halogen atom abstraction reactivity by 1-N.
107 citations
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01 Sep 2010
TL;DR: In this paper, the selection of the best choice of reaction conditions and ligand of this class for the most commonly encountered and practically important substrate combinations for Pd-catalyzed amination reactions is discussed.
Abstract: Dialkylbiaryl phosphines are a valuable class of ligand for Pd-catalyzed amination reactions and have been applied in a range of contexts. This perspective attempts to aid the reader in the selection of the best choice of reaction conditions and ligand of this class for the most commonly encountered and practically important substrate combinations.
966 citations
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TL;DR: The preparation strategies of COF NSs via bottom-up and top-down approaches are described, and the applications of bulk COFs and COFNSs in EES and EEC are summarized, such as in batteries, supercapacitors, and fuel cells.
Abstract: Covalent organic frameworks (COFs) as an emerging class of crystalline porous materials have received much attention due to their tunable porosity, modifiable skeletons, and atomically precise structures. Besides, COFs can provide multiple high-rate charge carrier transport (electron, hole, and ion) pathways, including conjugated skeletons, overlapped π electron clouds among the stacked layers, and open channels with a variable chemical environment. Therefore, they have shown great potential in electrochemical energy storage (EES) and conversion (EEC). However, in bulk COFs, the defects always impede charge carrier conduction, and the difficulties in reaching deep-buried active sites by either electrons or ions lead to limited performance. To overcome these obstacles, numerous research studies have been carried out to obtain COF nanosheets (NSs). This review first describes the preparation strategies of COF NSs via bottom-up and top-down approaches. Then, the applications of bulk COFs and COF NSs in EES and EEC are summarized, such as in batteries, supercapacitors, and fuel cells. Finally, key challenges and future directions in these areas are discussed.
484 citations
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27 Mar 2015TL;DR: In this paper, novel tricarbazole compounds with appropriate HOMO and LUMO energies can be obtained for use as materials in a secondary hole transport layer, by appropriately selecting the nature of the tricarazole substituents.
Abstract: Novel tricarbazole compounds are provided. By appropriately selecting the nature of the tricarbazole substituents, compounds with appropriate HOMO and LUMO energies can be obtained for use as materials in a secondary hole transport layer.
445 citations
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TL;DR: In this article, the authors summarize the recent progress on general strategies to suppress zinc dendrites and zinc anode side reactions based on advanced materials and structure design, including the modification of the planar zinc electrode surface layer, internal structural optimization of the zinc bulk electrode, modification of electrolyte and construction of the multifunctional separator.
Abstract: Rechargeable aqueous metal-ion batteries are very promising as alternative energy storage devices during the post-lithium-ion era because of their green and safe inherent features. Among the different aqueous metal-ion batteries, aqueous zinc-ion batteries (ZIBs) have recently been studied extensively due to their unique and outstanding benefits that hold promise for large-scale power storage systems. However, zinc anode problems in ZIBs, such as zinc dendrites and side reactions, severely shorten the ZIB's cycle lifetime, thus restricting their practical application. Here, we sum up in detail the recent progress on general strategies to suppress zinc dendrites and zinc anode side reactions based on advanced materials and structure design, including the modification of the planar zinc electrode surface layer, internal structural optimization of the zinc bulk electrode, modification of the electrolyte and construction of the multifunctional separator. The various functional materials, structures and battery efficiencies are discussed. Finally, the challenges for ZIBs are identified in the production of functional zinc anodes.
419 citations
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TL;DR: The development of photocatalytic C–H amination, alkylation, and arylation of methane, ethane, and higher alkanes under visible light irradiation at ambient temperature is reported.
Abstract: With the recent soaring production of natural gas, the use of methane and other light hydrocarbon feedstocks as starting materials in synthetic transformations is becoming increasingly economically attractive, although it remains chemically challenging. We report the development of photocatalytic C-H amination, alkylation, and arylation of methane, ethane, and higher alkanes under visible light irradiation at ambient temperature. High catalytic efficiency (turnover numbers up to 2900 for methane and 9700 for ethane) and selectivity were achieved using abundant, inexpensive cerium salts as photocatalysts. Ligand-to-metal charge transfer excitation generated alkoxy radicals from simple alcohols that in turn acted as hydrogen atom transfer catalysts. The mixed-phase gas/liquid reaction was adapted to continuous flow, enabling the efficient use of gaseous feedstocks in scalable photocatalytic transformations.
381 citations