检索结果-南通市图书馆

Self-assembly Induced by Complexation of Diblock Copolyelectrolytes and Oppositely Charged Homopolymers

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第9期42卷 1321-1332,I0006页

作者： Ling Zhao Zhi-Yuan Yin Jia-Di Jiang Er-Qiang Chen Shuang Yang beijing national laboratory for molecular sciences Key Laboratory of Polymer Chemistry and Physics of Ministry of EducationCenter for Soft Mater Science and EngineeringCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China beijing national laboratory for molecular sciences College of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China

We investigate the solution self-assembly of a mixture of positively charged homopolymers and AB diblock copolymers,in which the A blocks are negatively charged,and the B blocks are *** electrostatic complexation between oppositely charged polymers drives the formation of many ordered *** microstructures and phase diagrams are calculated using self-consistent field theory(SCFT)based on an ion-pair model with an equilibrium constant K to characterize the strength of binding between positively and negatively charged *** effects of the charge ratio,representing the ratio of charges from the homopolymer over all charges from polymers in the system,on the ordered structure are systematically studied,both for hydrophobic and hydrophilic A *** charge ratio plays an important role in determining the phase boundaries in the phase diagram of salt concentration versus polymer *** also provide information about the varying tendency of the domain spacing and core size of the spherical phase when the charge ratio is changed,and the results are in good agreement with *** studies provide a deep understanding of the self-assembled microstructures of oppositely charged diblock copolymer-homopolymer systems.

关键词： Self-assembly Polyelectrolyte complexation Self-consistent field theory Ion-pair

Capturing metal clusters at the strong-interaction region to reverse Ostwald ripening

在线全文

学校读者我要写书评

暂无评论

Science China Materials 2024年第4期67卷 1363-1364页

作者： Shuheng Tian Ding Ma beijing national laboratory for molecular sciences New Cornerstone Science LaboratoryCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

High-temperature interactions induce sintering of metal nanoparticles(NPs) on heterogeneous catalyst surfaces, leading to reduced surface area and active site loss through Ostwald ripening [1]. This irreversible deactivation necessitates costly catalyst replacement, notably impacting metals like copper in hydrogenation and reforming reactions [2].

关键词： catalyst reforming irreversible

C_(Ar)-Br bond cleavage via cooperative EnT/NHC catalysis: mild access to indolines

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第3期67卷 922-927页

作者： Yi-Xiong Dong Cao-Bo Li Ming-Lei Jin Zhong-Hua Gao Song Ye beijing national laboratory for molecular sciences CAS Key Laboratory of Molecular Recognition and FunctionCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of sciences Beijing 100049China

The cooperative visible-light mediated and NHC-catalyzed dearomative arylation-acylation of N-(2-bromobenzoyl)indoles with aldehydes was developed, affording the corresponding highly functionalized polycyclic indolines in moderate to good yields with exclusive diastereoselectivities. Mechanism investigations support the activation of CAr-Br bond via visible-light mediated energy transfer(EnT) and the following single-electron-transfer(SET) with Breslow intermediate under NHC catalysis to give key aryl radical and ketyl radical. This protocol demonstrates the cleavage of CAr-Br bond under mild cooperative EnT/NHC catalysis.

关键词： energy transfer N-heterocyclic carbenes photocatalysis aryl radicals indolines

A review on plasmonic enhancement of activity and selectivity in electrocatalytic CO_(2)reduction

在线全文

学校读者我要写书评

暂无评论

Frontiers in Energy 2024年第4期18卷 399-417页

作者： Jing XUE Zhenlin CHEN Yuchao ZHANG Jincai ZHAO Key laboratory of Photochemistry Beijing National Laboratory for Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of sciences Beijing 100049China

Utilizing plasmonic effects to assist electrochemical reactions exhibits a huge potential in tuning the reaction activities and product selectivity,which is most appealing especially in chemical reactions with multiple products,such as CO_(2)reduction reaction(CO_(2)RR).However,a comprehensive review of the development and the underlying mechanisms in plasmon-assisted electrocatalytic CO_(2)RR remains few and far ***,the fundamentals of localized surface plasmonic resonance(LSPR)excitation and the properties of typical plasmonic metals(including Au,Ag,and Cu)are ***,the potential mechanisms of plasmonic effects(such as hot carrier effects and photothermal effects)on the reaction performance in the field of plasmon-assisted electrocatalytic CO_(2)RR are summarized,which provides directions for the future development of this *** is concluded that plasmonic catalysts exhibit potential capabilities in enhancing CO_(2)RR while more in situ techniques are essential to further clarify the inner mechanisms.

关键词： localized surface plasmonic resonance(LSPR)effect plasmonic metals CO_(2)reduction reaction(CO_(2)RR) hot carrier effect photothermal effect

An unprecedented synthesis of axially chiral biaryls by rearrangement and aromatization of carbocations with central-to-axial conversion of chirality

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第9期67卷 2998-3003页

作者： Qi Liu Xue-Dong Li Liang Cheng Li Liu beijing national laboratory for molecular sciences(BNLMS) CAS Key Laboratory of Molecular Recognition and FunctionCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of sciences Beijing 100049China

The central-to-axial chirality conversion represents a fascinating class of chemical processes consisting of the destruction of stereogenic centers and the simultaneous installation of axial chiral elements,which provides efficient methods for the preparation of axially chiral ***,developing catalytic asymmetric approaches for constructing these central chirality precursors and the efficient central-to-axial chirality conversion remains a challenge due to the requirement of aromatization or elimination *** this work,we have developed an unprecedented enantioselective intramolecular FriedelCrafts alkylation with unactivated-ketone carbonyls from which a chiral tertiary alcohol was generated with high efficiency and excellent *** addition,the central-to-axial chirality conversion strategy has been successfully applied to the synthesis of enantioenriched biaryls via a less-explored carbocation-initiated rearrangement and aromatization under the promotion of Lewis *** methodology provided a straightforward and sustainable access to a broad range of biaryl-2-carboxylic acid and in excellent yields(up to 92%)and excellent central-to-axial chirality conversion(up to 99%conversion percentage).This work could be a great model for developing new methods for synthesizing axially chiral biaryls and a general protocol for the rearrangement and aromatization of carbocations for further functionalization.

关键词： br?nsted acid catalysis desymmetrization phosphoric acid axially chiral biaryls central-to-axial conversion

A Fluorine-Functionalized 3D Covalent Organic Framework with Entangled 2D Layers

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第8期42卷 1210-1216页

作者： Li-Bang Xiao Zi-Han Wu Jun-Jie Xin Yuan-Peng Cheng Bo Gui Jun-Liang Sun Cheng Wang College of Chemistry and molecular sciences Wuhan UniversityWuhan 430072China College of Chemistry and molecular Engineering Beijing National Laboratory for Molecular SciencesPeking UniversityBeijing 100871China

Constructing three dimensional(3D)covalent organic frameworks(COFs)through the entanglement of two dimensional(2D)nets is a promising but underdeveloped ***,we report the design and synthesis of a fluorine functionalized 3DCOF(3D-An-COF-F)formed by entangled 2D sql *** structure of 3D-An-COF-F was determined by the combination of continuous rotation electron diffraction technique and modelling based on the chemical information from real ***,compared to the isostructural 3D-An-COF without F atom s,3DAn-COF-F showed an improved CO_(2)sorption ability and higher CO_(2)/N_(2)*** study not only demonstrated the generality of constructing 3D COFs with entangled 2D nets by introducing bulky groups vertically in planar building blocks,but also will expand the diversity of 3D COFs for various applications.

关键词： 3D covalent organic frameworks Fluorine Entangled 2D layers Electron diffraction CO_(2)adsorption

Solid-state lithium-ion batteries for grid energy storage:opportunities and challenges

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第1期67卷 43-66页

作者： Xin Chang Yu-Ming Zhao Boheng Yuan Min Fan Qinghai Meng Yu-Guo Guo Li-Jun Wan CAS Key laboratory of molecular Nanostructure and Nanotechnology CAS Research/Education Center for Excellence in Molecular SciencesBeijing National Laboratory for Molecular Sciences(BNLMS)Institute of ChemistryChinese Academy of Sciences(CAS)Beijing 100190China University of Chinese Academy of sciences Beijing 100049China

The energy crisis and environmental pollution drive more attention to the development and utilization of renewable *** the capricious nature of renewable energy resource,it has difficulty supplying electricity directly to consumers stably and efficiently,which calls for energy storage systems to collect energy and release electricity at peak *** to their flexible power and energy,quick response,and high energy conversion efficiency,lithium-ion batteries stand out among multiple energy storage technologies and are rapidly deployed in the *** superior performance and ensuring the safety of energy storage systems,intrinsically safe solid-state electrolytes are expected as an ideal alternative to liquid *** this review,we systematically evaluate the priorities and issues of traditional lithium-ion batteries in grid energy *** lithium-ion batteries containing liquid electrolytes,solid-state lithium-ion batteries have the potential to play a more significant role in grid energy *** challenges of developing solid-state lithium-ion batteries,such as low ionic conductivity of the electrolyte,unstable electrode/electrolyte interface,and complicated fabrication process,are discussed in ***,the safety of solid-state lithium-ion batteries is *** the obtained insights,inspiring prospects for solid-state lithium-ion batteries in grid energy storage are depicted.

关键词： lithium-ion batteries grid energy storage solid-state electrolytes interface stability

Interplay between Microscopic Structures and Macroscopic Viscoelastic Properties of Polyampholyte Gels

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第9期42卷 1360-1367,I0008页

作者： You-Cai Xue Yi-Ming Yang Di Jia beijing national laboratory for molecular sciences Laboratory of Polymer Physics and ChemistryInstitute of ChemistryChinese Academy of SciencesBeijing100190China University of Chinese Academy of sciences Beijing100049China

Polyampholyte gels,which have hierarchical structures,exhibit excellent self-healing properties and have great promise for biomaterials and *** investigated the relationship between microscopic structures and macroscopic viscoelastic properties of polyampholyte gels and found three factors influencing their viscoelastic properties,including the chemical crosslinking bonds,topological entanglements controlled by monomer concentration,and the ionic *** strength plays a major role on the strength of ionic bonds.A crossover point of elastic modulus and loss modulus was observed in the dynamic frequency sweeps at low monomer concentration or low chemical crosslinking density for gels with intermediate strength of ionic *** solid-liquid transition signaled by the crossover point is a typical feature of dynamic associated gels,representing the dynamical association-dissociation of the ionic bonds and full relaxation of the topological entanglements in the gel *** the crossover point disappears when the ionic bonds are too weak or too strong to form“permanent”***,in the non-linear yielding measurement,gels with intermediate strength of the ionic bonds are ductile and yield at very large shear strain due to the self-healing properties and the dynamic association-dissociation of the ionic *** the self-healing properties disappear when the ionic bond strength is too weak or too *** work reveals the mechanism of how the dynamic association-dissociation of ionic bonds influences both the linear and non-linear viscoelastic properties of the polyampholyte gels.

关键词： Polyampholyte gel Ionic bond Topological entanglement Self-healing Hierarchical structure

Ultracycles consisting of macrocycles

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第5期35卷 183-188页

作者： Wen-Hui Mi Teng-Yu Huang Yu-Fei Ao Xu-Dong Wang Qi-Qiang Wang De-Xian Wang beijing national laboratory for molecular sciences CAS Key Laboratory of Molecular Recognition and FunctionInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of sciences Beijing 100049China

Presented here is a one-pot strategy starting from rationally designed macrocyclic precursors for the diverse construction of sophisticated *** type and amount of the base were found to significantly influence the macrocyclization *** use of 4.0 *** resulted in ultracycles of both types A and B while the presence of CsF larger than 6.0 *** only type B *** of anion template increased the total yields and affected the distribution of the *** ultracycles can accommodate large organic dicarboxylates anions via multiple anion-πand hydrogen bonds,and show selectivity to the size-matched heptanedioate(C7^(2−)).Based on all possible species and relevant equilibrium constants as well as material and charge balances,a numerical iterative algorithm was developed and applied to fit the association constants of B2H with dicarboxylates from glutarate(C5^(2−))to octanedioate(C8^(2−)),which gave association constants up to 10^(3) L/mol.

关键词： Ultracycles Diversity-oriented synthesis Anion recognition Anion-πinteraction