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Generation,bonding and reactivity of transient zinc-substituted silylenes

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Science China Chemistry 2024年第4期67卷 1256-1262页

作者： Cheng Xu Thayalan Rajeshkumar Laurent maron Xuebing Leng Yaofeng Chen State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of SciencesShanghai 200032China Spin-X Institute School of Chemistry and Chemical EngineeringState Key Laboratory of Luminescent Materials and DevicesGuangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional MaterialsSouth China University of TechnologyGuangzhou 510641China LPCNO CNRS&INSAUniversitéPaul SabatierToulous 31077France

The metal-substituted silylenes are of high interest,as the theoretical studies indicated that the silylenes with electropositive substituents have a small ΔE_(S-T)(singlet-triplet energy gap)or even the ground-state ***,such compounds are highly unstable,and only two transient alkali metal-substituted silylenes M(^(t)Bu_(3)Si)Si:(M=Li,K)were generated by photoextrusion of the alkali metal-substituted silacyclopropenes and merely studied by spectroscopic method(EPR)at low temperature(14 to 50 K).Herein,we report the generation of transient zinc-substituted silylenes from zinc silacyclopropanyl complexes under very mild and convenient *** generated transient zinc-substituted silylenes are highly reactive and undergo intermolecular cycloaddition with alkenes for the synthesis of zinc-substituted Si-heterocyclic *** there is no substrate,the zinc-substituted silylenes attack the C-C bonds of the β-diketiminato ligands and break the C-C *** studies further highlight the silylene nature of the zinc-substituted silylene and a very small ΔE_(S-T)(4.4 kcal/mol).

关键词： zinc complex silylene C-C bond cleavage cycloaddition DFT calculations

Dinitrogen cleavage and hydrogenation to ammonia with a uranium complex

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National Science Review 2023年第2期10卷 165-173页

作者： Xiaoqing Xin Iskander Douair Yue Zhao Shuao Wang Laurent maron Congqing Zhu State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials School of Chemistry and Chemical EngineeringNanjing University School of Medicine and Holistic Integrative Medicine Nanjing University of Chinese Medicine LPCNO CNRS and INSA Université Paul Sabatier State Key Laboratory of Radiation Medicine and Protection School for Radiological and Interdisciplinary Sciences (RAD-X) and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education InstitutionsSoochow University

The Haber-Bosch process produces ammonia(NH3) from dinitrogen(N2) and dihydrogen(H2),but re quires high temperature and *** iron-based catalysts were exploited in the current industrial Haber-Bosch process,uranium-based materials served as effective catalysts for production of NH3from *** some molecular uranium complexes are known to be capable of combining with N2,further hydrogenation with H2forming NH3has not been reported to ***,we describe the first example of N2cleavage and hydrogenation with H2to NH3with a molecular uranium *** N2cleavage product contains three uranium centers that are bridged by three imido μ2-NH ligands and one nitridoμ3-N *** experiments with15N demonstrate that the nitrido ligand in the product originates from *** of the N2-cleaved complex with H2or H+forms NH3under mild conditions.A synthetic cycle has been established by the reaction of the N2-cleaved complex with trimethylsilyl *** isolation of this trinuclear imido-nitrido product implies that a multi-metallic uranium assembly plays an important role in the activation of N2.

关键词： N_2 activation NH_3 formation depleted uranium uranium azide actinide coordination chemistry

Unusual selective reactivity of the rare-earth metal complexes bearing a ligand with multiple functionalities

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Science China Chemistry 2023年第1期66卷 117-126页

作者： Dongjing Hong Thayalan Rajeshkumar Shan Zhu Zeming Huang Shuangliu Zhou Xiancui Zhu Laurent maron Shaowu Wang Key Laboratory of Functional Molecular Solids Ministry of EducationAnhui Laboratory of Molecule-Based MaterialsCollege of Chemistry and Materials ScienceAnhui Normal UniversityWuhu 241000China Anhui Laboratory of Clean Catalytic Engineering Anhui Laboratory of Functional Coordinated Complexes for Materials Chemistiry and ApplicationCollege of Chemical and Environmental EngineeringAnhui Polytechnic UniversityWuhu 241000China LPCNO CNRS&INSAUniversite Paul Sabatier 135 Avenue de Rangueil31077 ToulouseFrance

Ligands play a key role in controlling activity of organometallic complexes so that development of new ligands to overcome the challenge is the main topic of modern *** first example of 1,1-hydride migratory insertion and intramolecular redox reaction has been realized in this work by applying a new ligand in rare-earth metal *** novel rare-earth metal complexes L^(Mes)RECH2Tms(THF)(RE=Y(1a),Dy(1b),Er(1c),Yb(1d),L^(Mes)=1-(3-(2,6-iPr_(2)C_(6)H_(3)N=CH)C8H4N)-CH_(2)CH_(2)-3-(2-CH2–4,6-Me_(2)C_(6)H_(2))-(N(CH)_(2)NC),THF=tetrahydrofuran)bearing a ligand with imino,indolyl,NHC(N-heterocyclic carbene)multiple functionalities were synthesized and *** of complexes 1 with silanes(PhSiH3or PhSiH2Me or PhSiD3)selectively produced the unprecedented 1,1-hydride(or deuterated H)migratory insertion of the indolyl moiety of the novel unsymmetrical dinuclear rare-earth metal complexes *** complex 2a reacts with Ph_(2)C=O to give the selective C=O double bond insertion to the RE–Co-methylene-Mesbond product 3a which further reacts with another Ph_(2)C=O(or DMAP,4-N,N-dimethylaminopyridine)affording the novelμ-η^(2):η^(3)-dianionic 3-iminoindolyl dinuclear rare-earth metal complex *** latter is formed through an unusual intramolecular redox reaction(through electron migration from the 2-carbanion of the indolyl ring to the imino motif)resulting in the re-aromatization of the indolyl ring.

关键词： rare-earth metal complexes indole N-heterocyclic carbene Fischer-type carbene 1 1-migratory insertion dianionic 3-iminoindolyl

New perspectives for mesenchymal stromal cells as an adjuvant therapy for infectious disease-associated encephalopathies

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Neural Regeneration Research 2022年第1期17卷 48-52页

作者： Maiara N.Lima Maria C.Barbosa-Silva Tatiana maron-Gutierrez Laboratory of Immunopharmacology Oswaldo Cruz InstituteOswaldo Cruz FoundationFiocruzRio de JaneiroRJBrazil National Institute of Science and Technology on Neuroimmunomodulation Rio de JaneiroBrazil

Knowledge of the mechanisms that trigger infection-related encephalopathies is still very limited and cell therapies are one of the most promising alternatives for neurodegenerative diseases,and its application in infectious diseases can be of great *** stromal cells are cells with great immunomodulatory potential;therefore,their use in clinical and preclinical studies in a variety of diseases,including central nervous system diseases,increased in the last *** stromal cells can exert their beneficial effects through several mechanisms,such as direct cell contact,through surface receptors,and also through paracrine or endocrine *** paracrine mechanism is widely accepted by the scientific community and involves the release of soluble factors,which include cytokines,chemokines and trophic factors,and extracellular *** mini review discusses mesenchymal stromal cells mechanisms of action in neurological disorders,the neuroinflammatory process that takes place in the brain as a result of peripheral inflammation and changes in the brain’s cellular scenario as a common factor in central nervous system diseases,and mesenchymal stromal cells therapy in *** stromal cells have been shown to act in neuroinflammation processes,leading to improved survival and mitigating behavioral *** recently,these cells have been tested in preclinical models of infectious diseases-associated encephalopathies(e.g.,cerebral malaria and sepsis associated encephalopathy)and have shown satisfactory results.

关键词： behavior cell therapy cognition encephalopathy malaria mesenchymal stromal cell sepsis

Are Sc-C and Sc-P Bonds Reactive in Scandium Phosphinoalkylidene Complex？ Insights on a Versatile Reactivity

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Chinese Journal of Chemistry 2018年第10期36卷 904-908页

作者： Weiqing Mao Li Xiang Carlos Alvarez Lamsfus Laurent maron Xuebing Leng Yaofeng Chen State Key Laboratory of Organometallic Chemistry Center for Excellence in Molecular Synthesis Shanghai Institute of Organic Chemistry Univer- sity of Chinese Academy of Sciences Chinese Academy of Sciences 345 Lingling Road Shanghai 200032 China LPCNO CNRS & INSA Universite Paul Sabatier 135 Avenue de Rangueil 31077 Toulouse France

The peculiar electronic structure of scandium phosphinoalkylidene complex [LSc{C（SiMe3）PPh2}THF] （L=[MeC（NDIPP）CHC（NDIPP）Me]-）, DIPP= 2,6-（Pr）2C6H3） leads to an interesting versatile reactivity, which is demonstrated both experimentally and computationally. The complex undergoes [2＋2] cycloaddition reactions with alkynes, and easily activates various X-O bonds such as C-O of propylene oxide, N-O of 3,5-dimethylisoxazole, B-O of pinacolborane and Si-O of triethoxysilane. These reactions occur on the Sc-C bond of the phosphinoalkylidene complex. Interestingly, the Sc-P bond can also be activated as the presence of a Sc-C-P three center π interaction in the complex allows performing C-F activation of 2,6-difluoro- pyridine and 1,2 addition with imine or ketone. The complex also reacts with metal complexes, [（COD）RhCl]2 and （Ph3P）AuCl, to form structural intriguing heterobimetallic complexes.

关键词： alkylidene density functional calculations multiple bonds phosphorus scandium

Collapse period of degrading SDOF systems

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Earthquake Engineering and Engineering Vibration 2014年第4期13卷 681-694页

作者： Borekci M Kircil ms Ekiz I Yildiz Technical University

Seismic demand estimation for a structure is a critical issue for seismic performance assessment so that the potential damage can be estimated realistically. Many researchers proposed simplified methods to estimate the demand of a structure under strong ground motions. However, most of them did not consider degradation and collapse potential of the structures. Even some of theme considered the degradation effect, stiffness and strength degradation effects were considered separately without collapse potential caused by dynamic instability. In this study, collapse potential of SDOF systems caused by dynamic instability with stiffness and strength degradation has been investigated. Nonlinear time history analyses were performed, using an energy-based, strength and stiffness degraded hysteretic model that considers the collapse potential, with 160 earthquake acceleration time histories. An equation was proposed for the estimation of collapse period of SDOF systems as a function of certain strength reduction factor, ductility level and post-capping stiffness ratio. Finally, effects of parameters of the considered hysteretic model and local site conditions on the collapse period were investigated.

关键词： collapse degradation dynamic instability hysteretic types,earthquake

心脏核磁共振成像技术在肥厚型心肌病中的应用现状及最新进展

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中华心血管病杂志 2009年第12期37卷 1057-1063页

作者： MartinS.maron Massachusetts 02111 Hypertrophic CardiomyopathyCenter Division of Cardiology. Tufts Medical Center

肥厚型心肌病足一种最为常见的遗传性心肌病，患病率约为1／500，是导致青年猝死的首要病因，也是引起不同年龄段心力衰竭与脑卒中的主要病因之一。肥厚型心肌病是一种常染色体显性遗传病，现已明确至少12个编码肌小节蛋白的基因突变，... 详细信息

肥厚型心肌病足一种最为常见的遗传性心肌病，患病率约为1／500，是导致青年猝死的首要病因，也是引起不同年龄段心力衰竭与脑卒中的主要病因之一。肥厚型心肌病是一种常染色体显性遗传病，现已明确至少12个编码肌小节蛋白的基因突变，导致心室肥厚的表型。

关键词：肥厚型心肌病核磁共振成像技术常染色体显性遗传病心脏遗传性心肌病心力衰竭基因突变心室肥厚

Rheological Behavior of Polymer Melts and Concentrated SolutionsPart V: A New Molecular Theory of Non-linear Viscoelasticity for Polymeric Suspensions

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Journal of Materials Science & Technology 1999年第2期15卷 169-177页

作者： Song, ms Zhou, W Hu, GX Hu, LJ Beijing Univ Chem Technol Inst Polymer Mat Beijing 100029 Peoples R China Harbin Inst Technol Dept Appl Chem Harbin 150001 Peoples R China

A double-network model is established, which consists of the segments, E and A-constituent chains, the polymeric chains entangled with other ones by multi-entanglement and polymeric chains connected to a great number of destructible particles by multi-adsorption, based on which the E and A-constituent chains can be recreated and released dynamically. The distribution function of the end-to-end vector, the statistical distribution function of conformation for two kinds of chains in the multi-entanglement and multi-adsorption states and their number of polymeric chains are calculated by the combination of statistical mechanics and kinetics. Then the viscoelastic free energies of deformation for two kinds of the networks and suspensions are calculated by Boltzmann's statistical theory. Also, elastic modulus and memory function for two kinds of the network and suspensions are derived. Consequently, a new molecular theory df the non-linear viscoelasticity for polymeric suspensions is proposed, and the constitutive equation and material function with yielding and thinning for the polymeric suspensions in different flow fields are derived from this theory.

关键词： Polymers

Two New Sesquiterpenes from Ligularia Intermedia

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Chinese Chemical Letters 1996年第12期7卷 1100-1102页

作者： Chen, HM Cai, ms Jia, ZJ BEIJING MED UNIV SCH PHARMACEUT SCIBEIJING 100083PEOPLES R CHINA LANZHOU UNIV DEPT CHEMLANZHOU 730000PEOPLES R CHINA

Two new sesquiterpenes were isolated from the rhizomes of Ligularia intermedia. Their structures were determined as eremophil-7(8)-en-12,8(4 beta, 6 alpha)-diolide(1) and eremophil-7(8)-en-12,8(4 beta, 6 beta)-diolide... 详细信息

关键词： New Sesquiterpenes from Ligularia Intermedia Two