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Design of S-band photoinjector with high bunch charge and low emittance based on multi-objective genetic algorithm

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Nuclear Science and Techniques 2023年第3期34卷 93-105页

作者： Ze-Yi Dai Yuan-Cun Nie Zi Hui Lan-Xin Liu Zi-Shuo Liu Jian-Hua Zhong Jia-Bao Guan Ji-Ke Wang Yuan Chen Ye Zou Hao-Hu Li Jian-Hua He The Institute for Advanced Studies Wuhan UniversityWuhan 430072China

High-brightness electron beams are required to drive LINAC-based free-electron lasers(FELs)and storage-ring-based synchrotron radiation light sources.The bunch charge and RMS bunch length at the exit of the LINAC play a crucial role in the peak current;the minimum transverse emittance is mainly determined by the injector of the LINAC.Thus,a photoin-jector with a high bunch charge and low emittance that can simultaneously provide high-quality beams for 4th generation synchrotron radiation sources and FELs is desirable.The design of a 1.6-cell S-band 2998-MHz RF gun and beam dynamics optimization of a relevant beamline are presented in this paper.Beam dynamics simulations were performed by combining ASTRA and the multi-objective genetic algorithm NSGA II.The effects of the laser pulse shape,half-cell length of the RF gun,and RF parameters on the output beam quality were analyzed and compared.The normalized transverse emittance was optimized to be as low as 0.65 and 0.92 mm·mrad when the bunch charge was as high as 1 and 2 nC,respectively.Finally,the beam stability properties of the photoinjector,considering misalignment and RF jitter,were simulated and analyzed.

关键词： Electron linear accelerator Photoinjector Beam dynamics Multi-objective genetic algorithm

Narrow bandgap molecular dyads incorporating Y-series acceptor backbones for efficient single-molecular organic solar cells

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Science China Chemistry 2023年第11期66卷 3205-3212页

作者： Yuan Gao Bo Xiao Shanshan Wang Mingxia Chen Wei Wang Xinrong Yang Yiming Shao Rui Sun Jie Min The Institute for Advanced Studies Wuhan UniversityWuhan 430072China

The performance of organic solar cells(OSCs)is mainly related to the bulk heterojunction(BHJ)microstructure of specific active layer systems,which is often in a metastable state.A promising strategy to address the abovementioned shortcomings of BHJs is to develop single-component active layer materials.Owing to the single-component small molecule materials with defined chemical structures generally exhibit poor absorption spectra,herein we first introduced narrow bandgap Y-series acceptors into the molecular skeleton of single-component materials,and designed two molecular dyads,SM-Et-1Y and SM-Et-2Y.The optical bandgaps(E_g~(opt)s)of the two dyads are 1.364 and 1.361 eV,respectively,which are much smaller than those of previously reported single-component molecules.Consequently,the SM-Et-2Y-based single-component OSCs(SCOSCs)showed a power conversion efficiency(PCE)of 5.07%,superior to SM-Et-1Y(2.53%),which is one of the highest PCEs reported for SCOSCs to date.Moreover,both SM-Et-1Y-and SM-Et-2Y-based devices exhibited excellent photo-stability,retaining over 90%of their initial performance after 250 h of continuous illumination.Our results provide a deeper understanding of the molecular backbone and a guiding principle for the rational design or selection of non-fullerene single-component materials with suitable donor/acceptor ratios.

关键词： donor-acceptor dyads single-material organic solar cells Y-series acceptors operational stability optical bandgap

Iron-Catalyzed Amide Bond Formation from Carboxylic Acids and Isocyanates

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Chinese Journal of Chemistry 2023年第23期41卷 3268-3274页

作者： Lingjian Zi Jing Zhang The Institute for Advanced Studies Wuhan UniversityWuhanHubei430072 China

We describe an iron-catalyzed amide bond formation from readily available carboxylic acids and isocyanates.This method utilizes an abundant and biocompatible iron catalyst and easily accessible starting materials,generates CO_(2) as the only byproduct,and features broad substrate scopes with good functional group compatibility.Therefore,it provides a cost-effective and practical protocol to access a diverse variety of amides.

关键词： Iroen Carboxylic acids Amides C—N bond formation Rearrangement

1,1-Regioselective alkenylboration of styrenes enabled by palladium catalysis

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中国化学快报:英文版 2023年第8期34卷 175-179页

作者： Dong Wu Hailiang Pang Guoyin Yin The Institute for Advanced Studies Wuhan UniversityWuhan 430072China

Despite the 1,2-difunctionalization reactions of styrenes have been well developed, the 1,1-regioselective addition reaction remains challenging. We disclose herein a palladium-catalyzed, highly 1,1-regioselective alkenylboration of styrenes by using alkenyl triflates and a diboron reagent as the coupling partners. A wide scope of styrenes derivatives and alkenyl triflates participate this reaction to provide the corresponding allyl boronates with high regioisomeric ratios. The success of this reaction is ascribed to the application of 1,10-phenanthroline-derivated ligand and the addition of ammonium chloride salt. Moreover, acrylate esters can also selectively afford the 1,1-alkenylboration products under the same reaction conditions.

关键词： Styrenes 1,1-Regioselectivity Chain-walking Palladium catalysis Allyl boronates

Towards climate neutrality for household energy consumption

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National Science Review 2022年第7期9卷 12-12页

作者： Ortwin Renn institute for advanced Sustainability studies

The Paris Agreement,reinforced by the 2021 conference in Glasgow,obliges all nations that have signed the agreements to reduce the release of greenhouse gases to zero within the next few decades.China’ s central government has made two signature commitments on climate,pledging that the country’ s carbon dioxide emissions will peak before 2030,and the country will achieve carbon neutrality before 2060,

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Reversing Conventional Site-Selectivity:Electrochemically Driven C(sp^(2))-H/C(sp^(3))-H Coupling with H_(2)Evolution

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CCS Chemistry 2023年第5期5卷 1086-1095页

作者： Xuelian Zheng Pan Peng Cheng Huang Qingquan Lu The Institute for Advanced Studies Wuhan UniversityWuhan 430072

Sustainable and site-selective C–H functionalization is still a challenge because of the comparable properties of bonds of the same type.Here,an electrochemical C(sp^(2))–H/C(sp^(3))–H coupling with aryl iodides is reported for the first time.The C(sp^(2))–H bond outperformed the much weaker C(sp^(2))–I bond participating in C(sp^(2))–H/C(sp^(3))–H coupling.This protocol features mild reaction conditions,good functional group tolerance,and scalability.Crosscoupling products with C–I bonds are versatile moieties for further synthetic manipulation,that can undergo Suzuki,Sonogashira,Ullmann-Ma,Catellani,Heck reactions,and so on to introduce new functional groups into target molecules with good yields.Mechanistic investigations showed that the site selectivity of the reaction is enabled by an iodineassisted[3,3]-sigmatropic rearrangement,and the interaction of hypervalent iodine generated in situ with an enolate is the rate-determining step.

关键词： electrosynthesis electrooxidation C–H functionalization oxidative coupling alkylation

Ni-catalyzed ligand-controlled divergent and selective synthesis

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Science China Chemistry 2023年第11期66卷 2951-2976页

作者： Yang Ke Wei Li Wenfeng Liu Wangqing Kong The Institute for Advanced Studies(IAS) Wuhan UniversityWuhan 430072China

Scaffold diversity is a key feature of a compound library and plays a pivotal role in its success in biological screening.Therefore,it is highly desirable to develop efficient strategies to rapidly construct structurally distinct and diverse“privileged”molecular scaffolds,thereby giving rise to compound libraries with selective and differing biological activities.This review covers recent efforts in this emerging field of Ni-catalyzed divergent and selective synthesis,and will focus on reactions using the same substrate to generate structurally diverse molecular scaffolds by varying the ligand backbone under otherwise almost identical reaction conditions.We hope that the field will be encouraged by the progress achieved,drawing attention to the design and development of new selective catalytic systems,and revealing new modes of catalytic transformation for broader synthetic applications.

关键词： nickel catalysis chemoselectivity regioselectivity stereoselectivity divergent synthesis

Integrating aryl chlorides into nickel-catalyzed 1,1-difunctionalization of alkenes

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Chinese Chemical Letters 2022年第12期33卷 5096-5100页

作者： Caocao Sun Guoyin Yin The Institute for Advanced Studies Wuhan UniversityWuhan 430072China

Difunctionalization of alkenes have developed into an important type of reactions for rapidly and efficiently assemble complex molecules.While extensive advancements have been achieved by the assistance of transition metal catalysis,the employment of cheap,abundant aryl chlorides as coupling partner is still a challenging task in this field.Herein,we report our first achievement in 1,1-difunctionalization of alkenes with aryl chlorides as coupling partners.The success is predominantly ascribed to the judicious selection of 1,2-diamine ligand.This study provides an efficient protocol for the synthesis of secondary benzyl boronates from easily accessible feedstock chemicals.Furthermore,the distinguished features of this method include excellent 1,1-regio-and chemoselectivity,good functional group tolerance and easily-operational catalytic reaction conditions.

关键词： Aryl chlorides Difunctionalization of alkenes Regioselectivity Nickel catalysis

Curvature geometry in 2D materials

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National Science Review 2023年第8期10卷 232-242页

作者： Nan Wei Yiran Ding Jiaqian Zhang Linyi Li Mengqi Zeng Lei Fu College of Chemistry and Molecular Sciences Wuhan University The Institute for Advanced Studies Wuhan University

The two-dimensional(2D) material family can be regarded as the extreme externalization form of the matter in the planar 2D space. These atomically thin materials have abundant curvature structures, which will significantly affect their atomic configurations and physicochemical properties. Curvature engineering offers a new tuning freedom beyond the thoroughly studied layer number, grain boundaries, stacking order,etc. The precise control of the curvature geometry in 2D materials can redefine this material family. Special attention will be given to this emerging field and highlight possible future directions. With the step-by-step achievement in understanding the curvature engineering effect in 2D materials and establishing reliable delicate curvature controlling strategies, a brand-new era of 2D materials research could be developed.

关键词： 2D materials curvature geometry deformation strain