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Understanding how charge-charge interaction affects the stereochemistry of enamine fluorination by chiral primary amine catalysis

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中国科学:化学英文版 2023年第10期66卷 2828-2835页

作者： Yanfang Han Kai Yang Long Zhang Sanzhong Luo Jin-Pei Cheng Center of Basic Molecular Science(CBMS) Department of ChemistryTsinghua UniversityBeijing 100084China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China

Electrostatic interaction, especially electrostatic attraction, usually plays critical roles in controlling the reactivity and selectivity in catalytic transformations;however, the like-charge repulsion, which is ubiquitous in physical systems, is rarely applied in reaction control. Herein we disclosed an unexpected like-charge repulsion induced enantio-control mode in primary aminecatalyzed fluorination reactions with 1-fluoro-2,4,6-trimethylpyridinium triflate. The ionic reaction works favorably in both highly polar(methanol) and non-polar(hexane) solvents, a seldom observed phenomenon in asymmetric catalysis. Erying plot analysis showed that an inversion temperature existed in Me OH, which was explained by the solvent-solute cluster model under different temperatures. Density functional theory(DFT) study and energy decomposition analysis(EDA) verified that the likecharge repulsion takes effect in polar solvent methanol, while in nonpolar solvents, the steric repulsion associated with ion-pair was found to be the major effect for the observed enantioselectivity.

关键词： aminocatalysis fluorination like-charge repulsion iso-inversion temperature ion-pair effect

Probing fluorination promoted sodiophilic sites with model systems of F_(16)CuPc and CuPc

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Frontiers of Optoelectronics 2022年第2期15卷 53-64页

作者： Yuan Liu Xu Lian Zhangdi Xie Jinlin Yang Yishui Ding Wei Chen Joint School of National University of Singapore and Tianjin University International Campus of Tianjin UniversityBinhai New CityFuzhou 350207China Department of Chemistry National University of Singapore3 Science Drive 3Singapore117543Singapore Centre for Advanced 2D Materials National University of Singapore6 Science Drive 2Singapore117546Singapore Department of Physics National University of Singapore2 Science Drive 3Singapore117542Singapore

Sodium metal batteries(SMBs)are receiving broad attention due to the high specific capacity of sodium metal anodes and the material abundance on earth.However,the growth of dendrites results in poor battery performance and severe safety problems,inhibiting the commercial application of SMBs.To stabilize sodium metal anodes,various methods have been developed to optimize the solid electrolyte interphase(SEI)layer and adjust the electroplating/stripping behavior of sodium.Among the methods,developing anode host materials and adding electrolyte additives to build a protective layer are promising and convenient.However,the understanding of the interaction process between sodium metal and those organic materials is still limited,but is essential for the rational design of advanced anode hosts and electrolyte additives.In this study,we use copper(II)hexadecafluorophthalocyanine(F_(16)CuPc),and copper(II)phthalocyanine(CuPc),as model systems to unravel the sodium interaction with polar functional groups by in-situ photoelectron spectroscopy and density functional theory(DFT)calculations.It is found that sodium atoms prefer to interact with the inner pyrrolic nitrogen sites of CuPc,while they prefer to interact with the outer aza bridge nitrogen atoms,owing to Na-F interaction at the Na/F_(16)CuPc interface.Besides,for the both organic molecules,the central Cu(II)ions are reduced to Cu(I)ions by charge transfer from deposited sodium.The fluorine-containing groups are proven to promote the interaction process of sodium in organic materials,which sheds light on the design of functional interfaces in host materials and anode protective layers for sodium metal anodes.

关键词： fluorination Phthalocyanines Sodium metal anode Sodiophilic sites In-situ X-ray photoelectron spectroscopy(XPS)

Effects of fluorination on crystal structure and electrochemical performance of antiperovskite solid electrolytes

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Journal of Energy Chemistry 2023年第2期77卷 521-528,I0013页

作者： Lei Gao Manrong Song Ruo Zhao Songbai Han Jinlong Zhu Wei Xia Juncao Bian Liping Wang Song Gao Yonggang Wang Ruqiang Zou Yusheng Zhao School of Materials Science and Engineering Peking UniversityBeijing 100871China Guangdong Provincial Key Laboratory of Energy Materials for Electric Power Guangdong-Hong Kong-Macao Joint Laboratory for Photonic-Thermal-Electrical Energy Materials and DevicesAcademy for Advanced Interdisciplinary StudiesSouthern University of Science and TechnologyShenzhen 518055GuangdongChina Institute for Advanced Study Shenzhen UniversityShenzhen 518055GuangdongChina

The development of all-solid-state lithium batteries(ASSLBs)depends on exploiting solid-state electrolytes(SSEs)with high ionic conductivity and electrochemical stability.fluorination is generally considered to be an effective strategy to improve the ionic conductivity and electrochemical stability of inorganic SSEs.Here,we report the partial fluorination of the chlo rine sites in an antiperovskite,by which the orthorhombic Li_(2)OHCl was transformed into cubic Li_(2)OHCl_(0.9)F_(0.1),resulting in a fourfold increase in ionic conductivity at 30℃.The ab initio molecular dynamics simulations suggest that both the crystal symmetry and the anions electronegativity influence the diffusion of Li+in the antiperovskite structure.Besides,from the perspective of experiments and calculations,it is confirmed that fluorination is a feasible method to improve the electrochemical stability of antiperovskite SSEs.The LiFePO_(4)|Li cell based on Li_(2)OHCl_(0.9)F_(0.1) is also assembled and exhibits stable cycle performance,which indicates that fluorination of antiperovskite SSEs is an effective way to produce high-performance SSEs for practical application of ASSLBs.

关键词： Antiperovskite Solid-state electrolyte fluorination Ionic conductivity

Selective fluorination on donor and acceptor for management of efficiency and energy loss in non-fullerene organic photovoltaics

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Science China Chemistry 2023年第4期66卷 1190-1200页

作者： You Chen Peng Lei Yanfang Geng Ting Meng Xiangyu Li Qingdao Zeng Qing Guo Ailing Tang Yufei Zhong Erjun Zhou CAS Center for Excellence in Nanoscience National Center for Nanoscience and TechnologyBeijing 100190China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Henan Institute of Advanced Technology Zhengzhou UniversityZhengzhou 450003China School of Materials Science and Engineering Ningbo Tech UniversityNingbo 315100China

Although fluorination has been proved effective to modulate optoelectronic properties and film morphology,knowledge of managing power conversion efficiency(PCE)and energy loss(Eloss)of organic photovoltaics(OPVs)by selective fluorination on the donor and/or acceptor is lacking.Herein we designed and synthesized three 1,2,3-benzotriazole(BTA)-based linear polymers(PE45,PE46 and PE47)with different numbers of fluorine atom substitution on the conjugated phenyl side chain.Two classic non-fullerene acceptors(NFAs)Y5(without fluorination)and Y6(with fluorination)were utilized to manage the device efficiency and energy loss.The results revealed that increasing fluorine substitutions on polymer donor improved the OPV efficiencies when the fluorinated Y6 was used as the acceptor,whereas decreased the PCEs when the non-fluorinated Y5 was used as the acceptor.The energy loss declined with the growing fluorine substitutions on polymer donor,and Y5 systems gave the lower values in comparison with the corresponding Y6 cases.It turns out that PE47:Y6 achieved the highest PCE of 15.58%with an open-circuit voltage(VOC)of 0.84 V(Eloss=0.56 e V)due to the highest and balanced hole/electron mobilities,suppressed bimolecular recombination and fibril network morphology,which is the highest value in the BTA-based polymers.Furthermore,PE47:Y5 attained an ultralow non-radiative energy loss of 0.15 e V,which is one of the lowest values among the reported OPVs.Our work could not only give a direct path on how to manage the efficiency and energy loss by selective fluorination on donor and acceptor,but also show a deep understanding on charge generation,transport and collection induced by selective fluorination.

关键词： fluorination D-π-A polymer non-fullerene acceptor energy loss organic solar cells

fluorination-mitigated high-current degradation of amorphous InGaZnO thin-film transistors

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半导体学报:英文版 2023年第9期44卷 57-61页

作者： Yanxin Wang Jiye Li Fayang Liu Dongxiang Luo Yunping Wang Shengdong Zhang Lei Lu School of Electronic and Computer Engineering Peking University Shenzhen Graduate SchoolShenzhen 518055China Huangpu Hydrogen Innovation Center/Guangzhou Key Laboratory for Clean Energy and Materials School of Chemistry and Chemical EngineeringGuangzhou UniversityGuangzhou 510006China Institute of Microelectronics Peking UniversityBeijing 100871China

As growing applications demand higher driving currents of oxide semiconductor thin-film transistors(TFTs),severe instabilities and even hard breakdown under high-current stress(HCS)become critical challenges.In this work,the triggering voltage of HCS-induced self-heating(SH)degradation is defined in the output characteristics of amorphous indium-galliumzinc oxide(a-IGZO)TFTs,and used to quantitatively evaluate the thermal generation process of channel donor defects.The fluorinated a-IGZO(a-IGZO:F)was adopted to effectively retard the triggering of the self-heating(SH)effect,and was supposed to originate from the less population of initial deep-state defects and a slower rate of thermal defect transition in a-IGZO:F.The proposed scheme noticeably enhances the high-current applications of oxide TFTs.

关键词： amorphous indium-gallium-zinc oxide(a-IGZO) thin-film transistors(TFTs) current stress self-heating(SH) fluorination

fluorination of suspended graphene

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Nano Research 2017年第9期10卷 3151-3163页

作者： Claudia Struzzi Mattia Scardamaglia Nicolas Reckinger Jean-Francois Colomer Hikmet Sezen Matteo Amati Luca Gregoratti Rony Snyders Carla Bittencourt Chimie des Interactions Plasma-Surface CIRMAP University of Mons 7000 Mons Belgium Research Group on Carbon Nanostructures (CARBONNAGe) University of Namur 5000 Namur Belgium Elettra - Sincrotrone Trieste S.C.p.A. di interesse nazionale Strada Statale 14 km 163.5 34149 Trieste Italy Materia Nova Research Center B-7000 Mons Belgium

Suspended graphene is exposed to different fluorine-containing species produced by a plasma source fed with CF4 precursor gas. We investigate the fluorination process by selecting two different kinetic energies for the ions striking the graphene surface. The chemical-bonding environment is discussed, and the control of the graphene-fluorination homogeneity is investigated at the individual graphene sheets. The modifications of the electronic and structural properties are examined by scanning photoelectron microscopy, micro-Raman analysis, and scanning electron microscopy. The results are compared with those obtained for supported graphene on copper. Suspended graphene provides a quasi-ideal model for investigating the intrinsic properties of irradiated carbon nano-systems while avoiding damage due to backscattered atoms and recoil due to a supporting substrate.

关键词： graphene fluorination spectromicroscopy X-ray photoelectron spectroscopy (XPS) Raman scanning electron microscopy (SEM)

fluorination over Cr doped layered perovskite Sr_(2)TiO_(4) for efficient photocatalytic hydrogen production under visible light illumination

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Journal of Energy Chemistry 2020年第12期29卷 30-38页

作者： Jinxing Yu Xiaoxiang Xu Clinical and Central Lab Putuo People’s HospitalTongji University1291 Jiangning RoadShanghai 200060China Shanghai Key Lab of Chemical Assessment and Sustainability School of Chemical Science and EngineeringTongji University1239 Siping RoadShanghai 200092China

Cr doped Ruddlesden-Popper compound Sr2 TiO4 has been successfully modified by fluorine to form a new compound Sr2 Ti(0.95) Cr(0.05) O3 F2. Structure analysis suggests two types of fluorine in the structure of this new compound, i.e. intralayer and interlayer F, which induce strong built-in electric field within this layered compound. The electric field stems from uneven distribution of F atoms on the two sides of perovskite layers therefore leads to charge disproportionation. DFT calculations suggest that this unique structural feature is highly beneficial for charge dissociations as it breaks the coplanar settlement of conduction band minimum and valence band maximum whilst maintains the 2 D charge transportation properties. This is clearly demonstrated by the superior photocatalytic activities of Sr2 Ti(0.95) Cr(0.05) O3 F2 for hydrogen production from water. Apparent quantum efficiency(AQE) as high as 1.16% at 420 ± 20 nm has been achieved which stands as the highest AQE reported on Sr2 TiO4 to date. Photoelectrochemical(PEC)analysis confirms improved charge separation conditions and prolonged charge lifetime.

关键词： DFT fluorination Sr_(2)TiO_(4) Photocatalytic water splitting 2D charge transportation

fluorination-substitution effect on all-small-molecule organic solar cells

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Science China Chemistry 2019年第7期62卷 837-844页

作者： Qiong Wu Dan Deng Jianqi Zhang Wenjun Zou Yang Yang Zhen Wang Huan Li Ruimin Zhou Kun Lu Zhixiang Wei CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China Sino-Danish College University of Chinese Academy of Sciences Beijing 100190 China

Due to the strong crystallinity and anisotropy of small molecules, matched molecular photoelectric properties and morphologies between small molecules and non-fullerene acceptors are especially important in all-small-molecule organic solar cells(OSCs).Introducing fluorine atoms has been proved as an effective strategy to achieve a high device performance through tuning molecular energy levels, absorption and assembly properties. Herein, we designed a novel benzodithiophene-based small molecule donor BDTF-CA with deep highest occupied molecular orbital(HOMO) energy level. All-small-molecule OSCs were fabricated by combing non-fullerene acceptor IDIC with different fluorine-atom numbers. Two or four fluorine atoms were introduced to the end-capped acceptor of IDIC, which are named as IDIC-2 F and IDIC-4 F, respectively. With the increase of fluorination from IDIC to IDIC-4 F, the open circuit voltage(Voc) of the devices decreased, while hole and electron mobilities of the active layers increased by one order of magnitude. Contributed to the most balanced Voc, short-circuit current(Jsc) and fill factor(FF), the device based on BDTF-CA/IDIC-2 F achieved the highest power conversion efficiency of 9.11%.

关键词： organic solar cells all-small-molecule fluorination blend morphology energy levels

fluorination strategy enables greatly improved performance for organic solar cells based on polythiophene derivatives

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Chinese Chemical Letters 2021年第7期32卷 2274-2278页

作者： Chenyi Yang Shaoqing Zhang Junzhen Ren Pengqing Bi Xiaotao Yuan Jianhui Hou School of Chemistry and Biology Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Polymer Physics and Chemistry Beijing National Laboratory for Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China

The power conversion efficiencies(PCEs)of organic solar cells(OSCs)have reached 18%recently,which have already met the demand of practical application.However,these outstanding results were generally achieved with donor-acceptor(D-A)type copolymer donors,which can hardly fulfill the low-cost largescale production due to their complicated synthesis processes.Therefore,developing polymer donors with simple chemical structures is urgent for realizing low-cost OSCs.Polythiophene(PT)derivatives are currently regarded as promising candidates for such kind of donor materials,which has been illustrated in many works.In this work,two new alkylthio substituted PT derivatives,P301 and P302,were synthesized and tested as donors in the OSCs using Y5 as the accepto r.In comparison,the introduction of fluorine atoms on the backbone of P302 can not only downshift the energy levels,but also greatly improve the phase separation morphologies of the active layers,which is ascribed to the enhanced aggregation effect and the reduced miscibility with the non-fullerene acceptor.As a result,the P302:Y5-based OSC exhibits a significantly improved PCE of 9.65%than that of P301:Y5-based one,indicating the important role of fluorination in the construction of efficient PT derivative donors.

关键词： Organic solar cells Polythiophene derivatives fluorination Aggregation effect Miscibility