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Spin effect on redox acceleration and regioselectivity in Fe-catalyzed alkyne hydrosilylation

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National Science Review 2024年第2期11卷 155-167页

作者： Peng He Meng-Yang Hu Jin-Hong Li Tian-Zhang Qiao Yi-Lin Lu Shou-Fei Zhu Frontiers Science Center for New organ.c Matter State Key Laboratory and Institute of Elemento-Organic Chemistry Nankai University

Iron catalysts are ideal transition metal catalysts because of the Earths abundant, cheap, biocompatible features of iron salts. Iron catalysts often have unique open-shell structures that easily undergo spin crossover in chem.cal transformations, a feature rarely found in noble metal catalysts. Unfortunately, little is known currently about how the open-shell structure and spin crossover affect the reactivity and selectivity of iron catalysts, which makes the development of iron catalysts a low efficient trial-and-error program. In this paper, a combination of experiments and theoretical calculations revealed that the iron-catalyzed hydrosilylation of alkynes is typical spin-crossover catalysis. Deep insight into the electronic structures of a set of well-defined open-shell active formal Fe(0) catalysts revealed that the spin-delocalization between the iron center and the 1,10-phenanthroline ligand effectively regulates the iron center's spin and oxidation state to meet the opposite electrostatic requirements of oxidative addition and reductive elimination, respectively,and the spin crossover is essential for this electron transfer process. The triplet transition state was essential for achieving high regioselectivity through tuning the nonbonding interactions. These findings provide an important reference for understanding the effect of catalyst spin state on reaction. It is inspiring for the development of iron catalysts and other Earth-abundant metal catalysts, especially from the point of view of ligand development.

关键词： spin effect spin-delocalization spin crossover iron-catalysis alkyne hydrosilylation

Cucurbit[8]uril-based non-covalent heterodimer realized NIR cell imaging through topological transformation from nanowire to nanorod

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Chinese chem.cal Letters 2024年第10期35卷 262-268页

作者： Jianqiu Li Yi Zhang Songen Liu Jie Niu Rong Zhang Yong Chen Yu Liu College of chem.stry State Key Laboratory of Elemento-Organic ChemistryNankai UniversityTianjin 300071China

In recent years,multicolor cascade supramolecular assemblies with controllab.e topological morphology have become a research hotspot due to their wide application in light-emitting materials,cell imaging and other ***,several kinds of macrocycles including cucurbiturils,calixarene and cyclodextrins are used as building blocks to construct fluorescent assemblies with anthryl-conjugated phenylpyridine(G),wherein cucurbit[8]uril(CB[8])and G can form nanowires at a stoichiometric ratio of n:n through host-guest encapsulation to form a non-covalent ***,the macrocycle confinement effect drastically enhances the fluorescence emission of G and emission peak generated bathochromic shift from 500 nm to 600 *** the supramolecular polymer is further assembled with amphiphilic calix[4]arene(SC_(4)A8),the fluorescence emission of G?CB[8]further increases to 1.4 times,accompanied by the morphological transformation from linear structure to nanorod ***,a very small amount of dye Cy5 is added to the assembly solution as an energy receptor,and the negatively charged G?CB[8]@SC_(4)A8 system is regarded as an energy *** efficient energy transfer process enables near-infrared(NIR)emission at 675 nm with 71%energy transfer efficiency(ΦET)at a donor/receptor ratio of 100:***,the cascade supramolecular assembly has been successfully applied to targeted imaging in the nucleus of HeLa and A549 cancer cells.

关键词： Multivalent assemblies Cucurbituril Morphological transformation Targeted imaging

In situ crosslink polymerization induced long-lived multicolor supramolecular hydrogel based on modifiedβ-cyclodextrin

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Chinese chem.cal Letters 2024年第2期35卷 374-379页

作者： Yonghui Sun Linnan Jiang Yong Chen Yu Liu College of chem.stry State Key Laboratory of Elemento-Organic Chemistry Nankai UniversityTianjin 300071China

The construction of hydrogels with good mechanical properties and phosphorescent properties is full of ***,we report a supramolecular phosphorescent hydrogel with long lifetime,high tensile strength and self-healing property,which can be easily constructed through in-situ thermalinitiated polymerization of isocyanatoethyl acrylate-modifiedβ-cyclodextrin(β-CD-DA)and acrylatemodified adamantane(Ad-DA),acrylic acid(AA),followed by the non-covalent association with carbon dots(CNDs).The lifetime of phosphorescent hydrogel can reach 1261 ms at room temperature,and the quantum yield is 11%.Importantly,through the efficient triplet to singlet Förster resonance energy transfer(TS-FRET),the phosphorescent hydrogel shows the good phosphorescence energy transfer property for organ.c dyes Rhodamine B and Eosin Y with the delayed fluorescence lifetime up to 730 ms and 585 ms as well as the energy transfer efficiency(Φ_(ET))up to 99.9%and 99.3%,***,owing to the host-guest interactions betweenβ-CD-DA and Ad-DA,the three-dimensional cross-linked network phosphorescent hydrogel can be easily stretched to 18 times of its original length,and can achieve self-healing of the cut surfaces within 30 *** results will expand the scope of phosphorescent materials and provide new ideas and opportunities for materials science.

关键词： Room temperature phosphorescence Hydrogel Phosphorescence energy transfer Cyclodextrin Supramolecular interaction

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

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Journal of Energy chem.stry 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 lab.ratory of elemento-organ.c chem.stry 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 electrochem.cal 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 10.3-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(0.07-10)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

Rhodium-Catalyzed Asymmetric Trifluoromethoxylation of Racemic Allylic Trichloroacetimidates

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CCS chem.stry 2024年第8期6卷 1885-1894页

作者： Liyan Wang Yafeng Si Yu-Xin Luan Pingping Tang state key lab.ratory and Institute of elemento-organ.c chem.stry College of ChemistryNankai UniversityTianjin 300071

A rhodium/diene catalyzed asymmetric allylic trifluoromethoxylation reaction is reported,which afforded chiral trifluoromethoxylated allylic compounds in 52%–97%yields with up to 97%enantiomeric *** are the first examples of asymmetric allylic *** reactions proceed via a dynamic kinetic process that allowed for the use of racemic allylic trichloroacetimidates as *** functional theory calculations showed that the formation of the C–OCF_(3)bond occurs via outer-sphere nucleophilic ***,the presence of the allylic group in the products enabled them to be converted into a diverse array of optically active trifluoromethylated molecules that are otherwise difficult to access.

关键词： asymmetric trifluoromethoxylation trifluoromethyl arylsulfonates rhodium trichloroacetimidates chiral diene ligand

organ.-electroreduction enables arylcarboxylation of styrenes

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Science China chem.stry 2024年第11期67卷 3825-3832页

作者： Yanwei Wang Qian Wang Zile Zhu Weikang Qi Youai Qiu state key lab.ratory and Institute of elemento-organ.c chem.stry Frontiers Science Center for New Organic Matter Haihe Laboratory of Sustainable Chemical Transformations College of Chemistry Nankai University

Electroreduction offers an alternative to generate high active intermediates from electrophiles(halides, alkenes, etc.) in organ.c synthesis. However, it still remains challenge to enable the transformations in controlled fashion for substrates with similar reduction potentials. Herein, an electroreductive arylcarboxylation of styrenes with aryl halides and CO2promoted by an organ.mediator has been developed. The reaction exhibits the remarkable reactivity control between styrenes and aryl halides bearing very similar reduction potentials, which is enabled by the addition of a simple organ.c mediator. The mediated process for different kinds of aryl halides(iodides and bromides) could be achieved by simply tuning the electronic effect of the skeleton of naphthalene. This protocol displays a broad substrate scope and the extension to late-stage modification of biorelevant molecules and their derivatives showed a bright prospect. Moreover, density functional theory(DFT) calculations and mechanistic studies have been conducted and provide solid support to rationalize the selectivity and reactivity control observed.

关键词： CO2 utilization reductive organ.-mediator carboxylation electroreduction aryl halides

Increase of chiral sensing ability in host-guest chem.stry by magnetic anisotropy

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Science China chem.stry 2024年第8期67卷 2775-2782页

作者： Jia-Liang Chen Bin Li Feng Yang Tiesheng Shi Xun-Cheng Su state key lab.ratory of elemento-organ.c chem.stry Tianjin Key Laboratory of Biosensing and Molecular RecognitionCollege of ChemistryNankai UniversityTianjin 300071China College of chem.stry Chemical Engineering and Materials ScienceZaozhuang UniversityZaozhuang 277160China

Enantiomeric molecules generally play distinct functions in chem.stry,biology,and *** physical and chem.cal properties of chiral analytes lay difficulty in discrimination and quantification of the *** report herein an efficient approach of increasing the chiral sensing ability ofβ-cyclodextrin(β-CD),a widely used host molecule,in the hostguest chem.stry by magnetic anisotropy.A rigid and chiral lanthanide binding tag was attached to theβ-CD to amplify the changes of nuclear magnetic resonance(NMR)signals in the host-guest recognition *** installation of the paramagnetic lanthanide ion inβ-CD greatly enhances the enantiomeric discrimination up to 30-fold in comparison with the diamagneticβ-CD *** addition,the magnitude of the paramagnetic effects is tunable according to the diverse range of paramagnetic strength of the lanthanide *** reported method significantly increases the chiral sensing ability ofβ-CD,which can be applied to other host *** transferred paramagnetic effects,pseudocontact shifts(PCSs)and paramagnetic relaxation enhancements(PREs),from the host to the guest molecules,are valuable structural restraints to determine the absolute stereochem.stry of the chiral *** strategy does not need modification of the analytes and is complementary to the reported analytical methods that rely on the functionalization of the chiral analytes.

关键词： chiral recognition nuclear magnetic resonance host-guest chem.stry magnetic anisotropy lanthanide ions

Ni-catalyzed highly regio- and stereo-selective diborylative cyclization of 1,6-enynes with diboron reagent

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Science China chem.stry 2024年第3期67卷 981-989页

作者： Qitao Guan Zhen Shen Yiqiang Tian Genping Huang Chun Zhang Institute of Molecular Plus Tianjin Key Laboratory of Molecular Optoelectronic ScienceDepartment of ChemistrySchool of SciencesTianjin UniversityTianjin 300072China state key lab.ratory of elemento-organ.c chem.stry Nankai UniversityTianjin 300071China

The Ni-catalyzed highly selective diborylative cyclization of 1,6-enynes with diboron reagent has been developed. When pinB-Bdan was used, multiple types of boron-containing functional groups could be installed into organ.c molecule with great chem.selectivity and regioselectivity though this reaction. Meanwhile, if B_2pai_2 was employed, the asymmetric diborylative cyclization could be well induced by using strategy of dynamic kinetic resolution. Importantly, the above reactions could afford desired product with 100% atomic economy, and could be compatible with different series of substituents. The studies of further transformation well illustrated that different type products could serve diverse synthetic strategy. Notably, the reaction mechanism was intensively studied by density functional theory(DFT) calculations, which could reveal the mechanism of regio- and enantio-selective control.

关键词： nickel-catalyzed organ.boron cyclization regioselectivity enantioselectivity

Stable Send-ketals of 3',5'-O-(Tetraisopropyldisiloxane-1,3-diyl)-2'-Ketouridine

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Chinese chem.cal Letters 1998年第11期9卷 989-992页

作者： Guo Chen CHI Zhong Biao ZHANG Xiao Hua Xu and Ru Yu CHEN (Insitute of elemento-organ.c chem.stry, state key lab.ratory of elemento-organ.c chem.stry,Nankai University, Tianjin, 300071) Insitute of elemento-organ. chem. State Key Lab. Elemento-Organ. Chem. Nankai University Tianjin 300071 China

A series of stable semi-ketals were obtained via the reactions of 3',5'-O-(tetraisopropyldisiloxane-1,3-diyl)-2'-ketouridine 1 with primary alcohols. In the addition reaction,only a single diastereomer was observed. T... 详细信息

关键词： Nucleoside ketonucleoside semi-ketal configuration