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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 Chemistry and laboratory of Organometallic Chemistry 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 1.48×10^(7) g PE·mol_(Zr)^(-1)·h^(-1) toward the polymerization of ethylene and afforded polyethylenes with high molecular weights(1.49×10^(5)-6.31×10^(5) g/mol), meanwhile exhibting great thermal stability at high temperatures up to 120 ℃ together with a long catalytic life time up to 2 h. By adopting low Al/Zr ratios, such as 125, polyethylenes with ultra high molecular weights up to 2.86×106 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

The critical role of energetic fluctuations in charge separation for efficient molecular doping of organic semiconductors

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Science China Chemistry 2024年第11期67卷 3675-3680页

作者： Yan Zeng Guangchao Han Yuanping Yi Beijing National laboratory for molecular Sciences CAS Key Laboratory of Organic Solids Institute of Chemistry Chinese Academy of Sciences University of Chinese Academy of Sciences

molecular doping is essential to improve the electrical conductivity of organic semiconductors for high-performance organic electronic devices. However, the doping efficiency is influenced by several factors, such as the energy levels, energetic fluctuations, dielectric properties, and molecular packing structures of the doped films, and the underlying mechanisms for highefficiency doping are still unclear. Here, through multi-level theoretical simulations on a series of fullerene derivatives, we identify that the energetic fluctuations can play a decisive role in activating charge separation for molecular doping. In particular,the doping efficiency appears to be exponentially increased with the fluctuation of charge polarization energies. Therefore,although the charge mobility is somewhat decreased, the experimental electrical conductivity is improved with the increased energetic fluctuation. Moreover, it has been found that polarization energy fluctuation can be effectively enhanced by simply introducing side chains with greater flexibility into organic semiconductors. This article paves the way towards high-efficiency molecular doping of organic semiconductors.

关键词： doping efficiency polarization energies energetic fluctuations organic semiconductors

“Three-in-one” strategy of trifluoromethyl regulated blood-brain barrier permeable fluorescent probe for peroxynitrite and antiepileptic evaluation of edaravone

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Chinese Chemical Letters 2024年第10期35卷 360-363页

作者： Lei Shen Hongmei Liu Ming Jin Jinchao Zhang Caixia Yin Shuxiang Wang Yutao Yang Key laboratory of Medicinal Chemistry and molecular diagnosis of the Ministry of Education Chemical Biology Key Laboratory of Hebei ProvinceState Key Laboratory of New Pharmaceutical Preparations and ExcipientsCollege of Chemistry and Materials ScienceHebei UniversityBaoding 071002China Key laboratory of Chemical Biology and molecular Engineering of Ministry of Education Institute of Molecular ScienceShanxi UniversityTaiyuan 030006China

Epilepsy,as a chronic neurological disease of the brain,is closely related to oxidative stress,and the peroxynitrite(ONOO-)significantly rise up in this ***,ONOO-is considered as a potential biomarker for early prediction of ***,some potential diagnostic reagents for epilepsy are hindered by the blood-brain barrier(BBB).Meanwhile,“drug repurposing”is attracting a growing ***(EDA),as a first-line drug in the clinical treatment of cerebral ischemia,plays antioxidant roles in scavenging free radicals,promising potential antiepileptic ***,it is imperative to develop fluorescent probes for monitoring ONOO-fluctuations in the epileptic ***,we proposed a novel fluorescent probe with the thiocarbonate as the promising recognition unit for ONOO-and dicyanoisophorone derivative as the ***,by the“three-in-one”strategy,the introduction of trifluoromethyl into DCI-ONOO-3 can extend the emission wavelength of the fluorophore,shorten the response and increase ***,DCI-ONOO-3 was used for monitoring ONOO-fluxes in brain of epileptic mice and evaluating the antiepileptic efficacy of *** opens up a new way for the design of BBB permeable fluorescent probes,and provides a convincing new method for the diagnosis and treatment of epilepsy.

关键词： Fluorescent probe Blood-brain barrier Peroxynitrite Epilepsy Drug repurposing

Enantioselective Construction of Polycyclic Chromanes through Organocatalytic Sequential Quintuple Reaction via One-Pot Step-Wise Procedure

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Chinese Journal of Chemistry 2024年第18期42卷 2197-2202页

作者： Jie Wang Hang Qin Ya-Li Song Fei Cao Zhi-Hao You Key laboratory of Pharmaceutical Quality Controlof Hebei Province College of Pharmaceutical SciencesHebei UniversityBaodingHebei 071002China Key laboratory of Medicinal Chemistry and molecular diagnosis of the Ministry of Education BaodingHebei 071002China

An efficient and highly stereoselective synthetic method to access polycyclic chromanes has been achieved through organocatalyzed one-pot step-wise reactions involving 2-hydroxycinnamaldehydes,2-aminochalcones,and malononitrile as *** reactions underwent a quintuple process by aza-Michael/Michael/Knoevenagel/oxa-Michael/aldol-type reaction in sequence to give products bearing 3 new generated rings and 5 chiral centers in moderate to quantitative yields with excellent stereoselectivities.

关键词： Asymmetric catalysis Organocatalysis Cyclization Quintuple reaction Polycycles Heterocycles Chromane One-pot reaction

Wood of trees:Cellular structure,molecular formation,and genetic engineering

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Journal of Integrative Plant Biology 2024年第3期66卷 443-467页

作者： Yingying Zhu Laigeng Li State Key laboratory of Herbage Improvement and Grassland Agro-ecosystems and College of Ecology Lanzhou UniversityLanzhou 730000China National Key laboratory of Plant molecular Genetics CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghai 200032China

Wood is an invaluable asset to human society due to its renewable nature,making it suitable for both sustainable energy production and material ***,wood derived from forest trees plays a crucial role in sequestering a significant portion of the carbon dioxide fixed during photosynthesis by terrestrial ***,with the expansion of the global population and ongoing industrialization,forest coverage has been substantially decreased,resulting in significant challenges for wood production and *** production practices have changed away from natural forests toward plantation ***,understanding the underlying genetic mechanisms of wood formation is the foundation for developing high-quality,fast-growing plantation *** ideal forest trees for wood production using genetic technologies has attracted the interest of *** studies have been carried out in recent years on the molecular,genetic,and cell-biological mechanisms of wood formation,and considerable progress and findings have been *** studies and findings indicate enormous possibilities and prospects for tree *** review will outline and assess the cellular and molecular mechanisms of wood formation,as well as studies on genetically improving forest trees,and address future development prospects.

关键词： cambium cell wall Populus wood formation xylem

Selective Alkane Desaturation Catalyzed by molecular Cage Copper Complexes Under Mild Conditions

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CCS Chemistry 2024年第8期6卷 1876-1884页

作者： Hao Sun Xue-Yuan Wang Xu-Dong Wang Yu-Fei Ao De-Xian Wang Qi-Qiang Wang Beijing National laboratory for molecular Sciences CAS Key Laboratory of Molecular Recognition and FunctionInstitute of ChemistryChinese Academy of SciencesBeijing 100190 University of Chinese Academy of Sciences Beijing 100049

Catalytic oxidative alkane desaturation by base metals with benign oxidants under mild conditions is highly attractive,as it could enable an efficient way to produce valuable olefin *** we report the design and synthesis of macrocyclic and molecular cage copper complexes in catalyzing highly selective cyclohexane desaturation with H_(2)O_(2)/O_(2).The macrocycles and cages possess two to three phenanthroline units connected by versatile binary linkers or tripodal *** compounds readily formed bi-and tri-nuclear copper complexes with confined cavities and adaptive coordination environments,as suggested by X-ray single crystal *** the catalytic oxidation of cyclohexane,a considerable yield of cyclohexene with unprecedented dehydrogenation/oxygenation selectivity up to 6.1:1 was achieved with the optimal cage compound *** and mechanistic experiments suggested a pronounced cage effect and radical-mediated *** high selectivity was attributed to a cooperative effect between the copper centers,which facilitated the second hydrogen atom abstraction on the trapped cyclohexyl radical and the inhibition of the Fenton process within the shielding cavity environment.

关键词： supramolecular catalysis macrocycles molecular cages phenanthroline alkane desaturation

Lanthanum promoting bone formation by regulating osteogenesis,osteoclastogenesis and angiogenesis

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Journal of Rare Earths 2024年第3期42卷 621-628,I0007页

作者： Dandan Zou Runlian Lin Yu Han Juan Jia Guoqiang Zhou Haisong Zhang Kun Ge Hebei Key laboratory of Chronic Kidney Diseases and Bone Metabolism Affiliated Hospital of Hebei UniversityBaoding071000China Key laboratory of Medicinal Chemistry and molecular diagnosis of the Ministry of Education Key Laboratory of Chemical Biology of Hebei ProvinceCollege of Chemistry and Environmental ScienceHebei UniversityBaoding071002China

With lanthanum(La) in agriculture, medicine, and the chemical industry, La shows accumulation in the body, especially in the bone, because of its similar structure to calcium. Moreover, La has a direct role in bone formation regulating osteoblasts and osteoclasts. Nevertheless, bone formation is complex under the regulation of osteogenesis, osteoclastogenesis, and angiogenesis in the bone microenvironment. It is difficult to comprehensively understand the regulation of bone homeostasis from a single kind of ***, some bone microenvironment-related cells and mouse calvaria culture models were used to study the regulatory effect of La-based compound-lanthanum nitrate(La(NO_(3))_(3)) on bone ***(NO_(3))_(3) has good biological safety, and the osteogenic differentiation is significantly increased under La(NO_(3))_(3) treatment for bone marrow mesenchymal stem cells(BMMSC). In contrast, the differentiation,maturation, and bone erosion ability of osteoclasts are significantly decreased. Meanwhile, the angiogenesis ability of human umbilical vein endothelial cells(HUVEC) is significantly promoted when treated with La(NO_(3))_(3). Furthermore, bone metabolism and angiogenesis are improved under La(NO_(3))_(3) treatment in the calvaria ex vivo culture model and BMMSC-HUVEC co-culture system. These results suggest that La has the beneficial effect of promoting bone metabolism and improving bone formation in the bone microenvironment.

关键词： Lanthanum Bone microenvironment Osteogenic differentiation Angiogenesis Rare earths

taBOX: A water-soluble tetraanionic rectangular molecular container for conjugated molecules and taste masking for berberine and palmatine

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Chinese Chemical Letters 2024年第5期35卷 175-178页

作者： Qihan Lin Jiabin Xing Yue-Yang Liu Gang Wu Shi-Jia Liu Hui Wang Wei Zhou Zhan-Ting Li Dan-Wei Zhang Department of Chemistry Shanghai Key Laboratory of Molecular Catalysis and Innovative MaterialsFudan UniversityShanghai 200438China

A water-soluble macrocycle that bears four carboxylate anions has been designed and prepared,which forms a rectangular cavity that can efficiently encapsulate discrete electron-deficient aromatic compounds,including berberine and *** macrocycle is revealed to be highly biocompatible and able to inhibit the bitter taste of the two drugs.

关键词： Macrocycle Multianion molecular container molecular recognition Bitter taste masking

Intracellular RNA Labeling Technologies for the Analysis of RNA Biology

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Chinese Journal of Chemistry 2024年第7期42卷 790-801页

作者： Ruiqi Zhao Xin Fang Xiaocheng Weng Department of Clinical laboratory Center for Gene DiagnosisDepartment of NeurosurgeryZhongnan Hospital of Wuhan UniversityWuhanHubei 430071China College of Chemistryand molecular Sciences Key Laboratory of Biomedical Polymers-Ministry of EducationWuhan UniversityWuhan Hubei 430072China

As a cornerstone of the central dogma of molecular biology,RNA plays vital roles in living *** the past few decades,many RNA labeling technologies have been developed to elucidate the biological function of *** technologies have signifi-cantly advanced our understanding of RNA secondary structure,localization,and ***,taking advantage of these innovative RNA labeling approaches,plenty of tool kits have been devised for the regulation of RNA-related biological process,such as gene expression and gene *** this review,we primarily focus on an array of intracellular RNA labeling methods,encom-passing chemical probes-based labeling,metabolic labeling,and proximity-dependent *** also provide a brief overview of their applications in the research of RNA ***,the perspectives of RNA labeling are also discussed.

关键词： RNA Chemical probes Metabolic labeling Proximity-dependent labeling RNA structures Gene sequencing RNA recognition