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Access to High-Molecular-Weight Polyethylenes through High Temperature Ethylene Polymerization Catalysed by Ethylene-Bridged ansa-(3-R-Cyclopentadienyl)(Fluorenyl) Zirconocene Complexes

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Chinese Journal of Polymer Science 2024年第1期42卷 42-51,I0007页

作者： Bo Li Haiyan Ma Jiling Huang Shanghai Key laboratory of Functional Materials {1. and laboratory of Organometallic {1. School of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China

A series of C1.symmetric ethylene-bridged ansa-(3-R-cyclopentadienyl)(fluorenyl) metallocene complexes(Zr: 1.5;Hf: 6) have been synthesized, characterized and investigated as catalyst precursors for the high temperature ethylene polymerization. Using methylaluminoxane(MAO) as the cocatalyst, zirconium complexes 1.5 bearing a bulky substituent on the 3-position of the cyclopendienyl ring showed high catalytic activities up to 1.48×1.^(7) g PE·mol_(Zr)^(-1.·h^(-1. toward the polymerization of ethylene and afforded polyethylenes with high molecular weights(1.49×1.^(5)-6.31.1.^(5) g/mol), meanwhile exhibting great thermal stability at high temperatures up to 1.0 ℃ together with a long catalytic life time up to 2 h. By adopting low Al/Zr ratios, such as 1.5, polyethylenes with ultra high molecular weights up to 2.86×1.6 g/mol were obtained. It is worthy of noting that zirconium complexes 1.4 bearing a substituent with an aryl pendant showed temperature-dependent activities, which increased rapidly with the increase of polymerization temperature, thus weak interaction of the pendent aryl group with the cationic active center is proposed to account for the very low activities displayed at low temperatures. In contrast to zirconocene complexes 1.5, hafnocene complex 6 only displayed very low catalytic activities toward the polymerization of ethylene and afforded polyethylenes with molecular weights ten times smaller than those obtained by zirconocene complexes 1.5. Zirconocene complexes 1.5 were also able to catalyse the polymerization of propylene at high temperatures, but only afforded waxes with low molecular weights.

关键词： ansa-Metallocene Ethylene Propylene Polymerization High temperature

Synergistic enhancement of ultrasound therapy for tumors using hypoxia-activated 6-diazo-5-oxo-L-norleucine(DON)prodrug nanoparticles

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Nano Research 2024年第7期17卷 6323-6331页

作者： Mengfei Zheng Zhilin Liu Hang Xu Daping Ye Linjie Cui Chenguang Yang Lili Ma Kun Wang Kazuo Sakurai Zhaohui Tang Key laboratory of Polymer Ecomaterials Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China School of Applied chemistry and Engineering University of Science and Technology of ChinaHefei 230026China Jilin Biomedical Polymers Engineering laboratory Changchun 130022China Department of chemistry and Biochemistry The University of Kitakyushu1-1 HibikinoKitakyushu 808-0135Japan

Ultrasound(US)has been applied in clinical practice for its non-invasive and high ***,it is difficult to achieve a satisfactory anti-tumor effect with US ***,the use of US therapy alone can exacerbate tumor *** this study,we prepared hypoxia-activated 6-diazo-5-oxo-L-norleucine(DON)prodrug nanoparticles(HDON-NPs)to improve US therapeutic *** an H22 murine liver cancer model,US therapy selectively disrupted tumor blood vessels,leading to increased tumor hypoxia and a 1.67-fold increase in the expression of nitroreductase(NTR).The combination therapy of US and HDON-NPs demonstrated a synergistic effect,resulting in a tumor suppression rate(TSR)of 90.2%±6.4%,which was 5.93-fold higher than that of US therapy *** combined treatment selectively blocked the glutamine metabolism of the tumor cells while simultaneously activating the T cells in the tumor microenvironment,thereby exerting a robust anti-tumor effect.

关键词： ultrasound therapy hypoxia-activated prodrug nanoparticles 6-diazo-5-oxo-L-norleucine(DON) glutamine antagonist starvation therapy

Manipulating submolecular-scale phototautomerization

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Science China Materials 2024年第6期67卷 2048-2050页

作者： Ping Zhou Hongliang Chen Stoddart Institute of Molecular Science Department of ChemistryZhejiang UniversityHangzhou 310058China Zhejiang-Israel Joint laboratory of {1.-Assembling Functional Materials ZJU-Hangzhou Global Scientific and Technological Innovation CenterZhejiang UniversityHangzhou 311215China

A recent study on the submolecular-scale control of phototautomerization methods and the underlying reaction mechanisms was reported in Nature Nanotechnology by Guillaume and co-workers[1.,elucidating how the field confinement effect generated by the scanning tunneling microscope(STM)tip precisely triggers the phototautomerization of a free-base phthalocyanine at the submolecular level and demonstrating that the reaction process can be finely controlled by adjusting either the laser excitation wavelength or the position of the tip.

关键词： tunneling excitation phthalocyanine

Cucurbit[8]uril-regulated face-to-face dimerization assembly enhanced photosensitization and photocatalysis

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Science China chemistry 2024年第5期67卷 1605-1612页

作者： Haigen Nie Die Hu Zhiyao Zeng Yan Fan Yaxin Zhai Xin-Long Ni Key laboratory of Chemical Biology and Traditional Chinese Medicine Ministry of Educational of ChinaKey Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan ProvinceCollege of Chemistry and Chemical EngineeringHunan Normal UniversityChangsha 410081China Key laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of PhysicsHunan Normal UniversityChangsha 410081China

In water, N,N′-diarylpyridinium thiazolo[5,4-d]thiazole guests(G1.G3) were encapsulated by cucurbit[8]uril(Q[8]) to construct Q[8]_(3)/G_(2) complexes, in which the encapsulated G molecules exist as an exact face-to-face dimer. These complexation behaviors have been indicated by proton nuclear magnetic resonance(~1. NMR) spectroscopy and isothermal titration calorimetry(ITC),and have been confirmed by X-ray single crystal structural analysis of Q[8]_(3)/G2_(2). While free guests G1.G3 have no ability to sensitize singlet oxygen, they all become effective singlet oxygen sensitizers when complexed with Q[8]. By irradiation of white light, Q[8]_(3)/G_(2) complexes induced selective oxidation of aryl sulfide to aryl sulfoxide in good yields and selective oxidation of dimethyl sulfide(DMS) to dimethyl sulfoxide(DMSO) in excellent yields without over-oxidation to dimethyl sulfone(DMSO_(2))even for elongated irradiation. High-yield photo-oxidation of DMS to DMSO_(2) was only achieved by irradiation of blue light in the presence of Q[8]_(3)/G1.(2), which was also effective in photobleaching of Rhodamine B in water. The higher photo-oxidation power of Q[8]_(3)/G1.(2) has been ascribed to an additional generation of reactive oxygen species besides singlet oxygen.

关键词： host-guest interaction dimerization macrocycles photosensitization

Electric-field-controlled highly regioselective thiocyanation of N-containing heterocycles

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Science China chemistry 2024年第4期67卷 1263-1269页

作者： Ming Gong Qian Wu Jung Keun Kim Mengmeng Huang Yabo Li Yangjie Wu Jong Seung Kim Henan Key laboratory of Chemical Biology and Organic {1. Key Laboratory of Applied Chemistry of Henan UniversitiesCollege of ChemistryZhengzhou UniversityZhengzhou 450052China Department of chemistry Korea UniversitySeoul 02841Korea

Achieving highly regioselective synthesis in organic chemistry is challenging due to the uncontrollable orientation between reacting *** electric fields(EEFs)can influence the reactivity and selectivity of the substrate by causing directional ***,scalable and efficient techniques for using EEFs as“smart catalysts”have been lacking,hindering their *** this study,we present a novel method for modifying the regioselectivity of quinoxaline-2(1.)-ones by functionalizing their C7-position using the electric double layer(EDL)*** approach led to moderate to good yields of the corresponding C7-thiocyanation *** calculations and control experiments demonstrated that EEFs could reverse the regioselectivity of quinoxaline-2(1.)-ones,allowing the C7-thiocyanation to proceed via a radical reaction ***,the resulting 7-thiocyano-1.methylquinoxaline-2(1.)-ones exhibited promising AIE *** work showcases a promising strategy for achieving highly regioselective functionalization by aligning the electric field with the desired reaction/bond axis.

关键词： electric fields reaction-axis rule electric double layer C7-thiocyanation C-S bond formation

Performance enhancement and active sites identification of Cu-Cd bimetallic oxide derived catalysts for electrochemical CO_(2) reduction

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Journal of Energy chemistry 2024年第4期91卷 50-58页

作者： Cai Wang Xin Hu Bairong Chen Houan Ren Xiaoyu Wang Yilin Zhang Xinyu Chen Yuping Liu Qingxin Guan Wei Li State Key laboratory of Elemento-Organic {1. Key Laboratory of Adv.Energy Mater.Chemistry(Ministry of Education)College of ChemistryNankai UniversityTianjin 300071China

The development of earth-abundant electrocatalysts with high performance for electrochemical CO_(2)reduction(ECR)is of great ***-based catalysts have been widely investigated for ECR due to their unique ability to generate various carbonaceous products,but directing selectivity toward one certain product and identifying the real active sites during ECR are still full of ***,after the incorporation of CdO into CuO,the Cu_(0.5)Cd_(0.5)-O catalyst achieves a 1..3-fold enhancement for CO selectivity in comparison with CuO,and a CO faradic efficiency nearly 90%with a current density around20 mA cm^(-2)could maintain at least 60 ***,a wide CO/H_(2)ratio(0.07-1.)is reached on Cu_(x)Cd_(1.x)-O catalysts by varying the Cu/Cd ratio,demonstrating the potential of syngas production using such *** results of ex situ XRD,XPS,and in situ Raman reveal that the real active sites of Cu_(0.5)Cd_(0.5)-O catalysts for CO production during ECR reaction are the reconstructed mixed phases of CuCd alloy and CdCO_(3).In situ FTIR and theoretical calculations further implicate the presence of Cd related species promotes the CO desorption and inhibits the H_(2)evolution,thus leading to an enhanced CO generation.

关键词： CO_(2)reduction Cu-Cd bimetallic Real active sites CO production

Molecule aging induced by electron attacking

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Journal of Energy chemistry 2024年第6期93卷 519-525,I0013页

作者： Ping Song Yining Dong Xue Gong Mingbo Ruan Baoxin Ni Xuanhao Mei Kun Jiang Weilin Xu State Key laboratory of Electroanalytical {1. and Jilin Province Key laboratory of Low Carbon Chemical Power Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022JilinChina School of Applied chemistry and Engineering University of Science and Technology of Chin1Hefei 230026AnhuiChina Shanghai Key laboratory of Molecular Catalysis and Innovative Materials Collaborative Innovation Center of Chemistry for Energy MaterialsDepartment of ChemistryFudan UniversityShanghai 200438China

Here we propose a new concept of"molecule aging":with some special treatment,a molecule could be"aged"by losing some unknown tiny particles or pieces from atoms in the molecule,Such"aging"or loss of unknown tiny particles does not change apparently its molecular structure or chemical composition,but some physicochemical properties could be changed *** further confirm such"molecule aging"via a long-term electron attacking to age water(H_(2)O)*** IR spectra show no structural difference between the fresh water and the aged one,while the NMR spectra show that the electron attacking can decrease the size of water *** facts indicate that the electron attacking indeed can"affect"the structure of water molecule slightly but without damaging to its basic molecule *** exploration reveals that the hydrogen evolution reaction(HER)activity of the aged water molecule is lower than the fresh water on the same Pt/C *** density functional theory calculations indicate that the shortened O-H bond in H_(2)O indeed can present lower HER activity,so the observed size decrease of water clusters from NMR probably could be attributed to the shortening of O-H bond in water *** results indicate significantly that the molecule aging can produce materials with new functions for new possible applications.

关键词： Aging of molecules Electron attacking Full width at half maxima Hydrogen evolution reaction

Impact of Pd single-site coordination structure on catalytic performance for semihydrogenation of acetylene

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Nano Research 2024年第9期17卷 8243-8249页

作者： Yu Zeng Minqi Xia Fujie Gao Changkai Zhou Xueyi Cheng Liwei Liu Liu Jiao Qiang Wu Xizhang Wang Lijun Yang Yining Fan Zheng Hu Key laboratory of Mesoscopic {1. of MOE and Jiangsu Provincial laboratory for Nanotechnology School of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China

Semihydrogenation of trace acetylene in an ethylene gas stream is a vital step for the industrial production of polyethylene,in which Pd single-site catalysts(SSCs)have great ***,two Pd SSCs with different coordination structures are prepared on hierarchical nitrogen-doped carbon nanocages(hNCNC)by regulating the nitrogen species with or without using *** using dicyandiamide,the obtained Pd1.Ndicy/hNCNC SSC features the coordinated Pd by two pyridinic N and two pyrrolic N(PdN^(py)_(2)N^(pr)_(2)).Without using dicyandiamide,the obtained Pd1.hNCNC SSC features the coordinated Pd by pyridinic N and C(PdN^(py_(x)C_(4-x)),x=1.4).The former exhibits an 1.-fold increase in catalytic activity compared to the *** results reveal the abundant unoccupied orbital states above the Fermi level of moiety,which can facilitate the activation of substrate molecules and dynamics of acetylene hydrogenation as supported by the combined theoretical and experimental *** addition,PdN^(py)_(2)N^(pr)_(2)the moiety presents a favorable desorption of ***,the Pd1.Ndicy/hNCNC SSC exhibits high C2H2 conversion(99%)and C2H4 selectivity(87%)at 1.0℃.This study demonstrates the impact of Pd single-site coordination structure on catalytic performance,which is significant for the rational design of advanced Pd SSCs on carbon-based supports.

关键词： coordination structure hierarchical nitrogen-doped carbon nanocages palladium semihydrogenation of acetylene singlesite catalysts

Chiral electron transporting material for circularly polarized organic light-emitting diode

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Science China chemistry 2024年第11期67卷 3777-3784页

作者： Peihao Huo Tianyu Yang Peiyu Fang Yujia Li Nanlong Zheng Min Gong Zuqiang Bian Zhiwei Liu Beijing National laboratory for Molecular Sciences State Key Laboratory of Rare Earth Materials Chemistry and ApplicationsCollege of Chemistry and Molecular Engineering Peking University

Circularly polarized organic light-emitting diode(CP-OLED) has attracted increasing interest for its efficient ability to generate circularly polarized light directly. So far, many CP-OLEDs were successfully fabricated with chiral emitters or chiral hosts. In this study, a new strategy based on chiral electron transporting layer is proposed to construct CP-OLEDs. A pair of chiral electron transporting materials, 1.3,5-tris((R/S)-4-isopropyl-4,5-dihydrooxazol-2-yl)benzene((R/S)-TOxiPr), are firstly designed and synthesized. The crystalline films of(R/S)-TOxiPr show circularly polarized photoluminescence with photoluminescence dissymmetry factors of-0.067 and +0.041. respectively. The CP-OLEDs based on(R/S)-TOxiPr and three types of achiral emitters all exhibit circularly polarized electroluminescence, showing feasibility and strong versatility of this new strategy. The mechanism is attributed to in-situ electrical excitation instead of simply light filtering of non-circularly polarized light. This work demonstrates a new approach for realizing circularly polarized electroluminescence which may provide a valuable strategy to develop CP-OLEDs.

关键词： circularly polarized organic light-emitting diodes chiral electron transporting layer trisoxazolinylbenzene circularly polarized electroluminescence