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Influence of steric and intramolecular inductive effects on the variable trends in R-X (R=Alkyl) bond dissociation energy

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Science china chemistry 2009年第7期52卷 943-951页

作者： cao chenzhong school of chemistry and chemical engineering, hunan university of Science and {3., xiangtan 411201, china school of chemistry and chemical {3. Hunan University of Science and Technology Xiangtan China

The question "why are the variation trends of R-X bond dissociation energy different?" is answered. The R-X bond dissociation energy (BDE) may be influenced by three main factors: the C-X intrinsic bond energy, the 1,3.geminal repulsion, and the intramolecular charge-induced dipole. In the presence of atom X, the variation trend of BDE in R-X (R= Me, Et, i-Pr, t-Bu) is dominated by two factors, the 1,3.geminal repulsion and the intramolecular charge-induced dipole. The former decreases the R-X BDE, and the latter either increases or decreases the R-X BDE. For the series of R-X with the R-C bond (such as R-Me, R-CH == CH2, R-C≡CH, and R-CN), the 1,3.geminal repulsion decreases the R-X BDE, and the variation trends of R-C BDE decrease from Me to t-Bu. As regards the series of R-X (such as R-H, R-BH2, and R-SiH2) in which the electronegativity of atom X is smaller than that of the carbon atom, the above two factors decrease the R-X BDE, and the variation trends of the R-X BDE decrease from Me to t-Bu. As to the series of R-X (such as R-F, R-OH, R-Cl, R-Br, R-I, and R-NH2) in which the electronegativity of atom X is larger than that of the carbon atom, the 1,3.geminal repulsion decreases the R-X BDE, while the intramolecular charge-induced dipole increases the R-X BDE. In this case, the variation trends of R-X BDE depend on the competition of the two factors. As a result, some of them (e. g., R-F, R-OH) increase from Me to t-Bu, some (e. g., R-I) decrease from Me to t-Bu, and some (e. g., R-Br) change very little.

关键词： bond dissociation energy charge-induced dipole geminal repulsion ionic configuration

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Improving the electrocatalytic performances of Pt-based catalysts for oxygen reduction reaction via strong interactions with single-CoN_(4)-rich carbon support

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Chinese chemical Letters 2024年第5期35卷 265-271页

作者： Jin Long Xingqun Zheng Bin Wang chenzhong Wu Qingmei Wang Lishan Peng Guizhou university Key Laboratory of Green chemical and Clean Energy technology Guizhou University Engineering Research Center of Efficient Utilization for Industrial WasteInstitute of Dual-carbon and New Energy Technology Innovation and Development of Guizhou ProvinceSchool of Chemistry and Chemical EngineeringGuizhou UniversityGuiyang 550025China College of Safety engineering Chongqing University of Science&TechnologyChongqing 401331China Key Laboratory of Rare Earths Chinese Academy of SciencesGanjiang Innovation AcademyGanzhou 341119China

Developing platinum-group-metal(PGM)catalysts possessing strong metal-support interaction and controllable PGM size is urgent for the sluggish oxygen reduction reaction(ORR)in proton-exchange membrane fuel ***,we propose an in-situ self-assembled reduction strategy to successfully induce highly-dispersed sub-3.m platinum nanoparticles(Pt NPs)to attach on resin-derived atomic Co coordinated by N-doped carbon substrate(Pt/Co_(SA)-N-C)for *** be specific,the interfacial electron interaction effect,along with a highly robust Co_(SA)-N-C support endow the as-fabricated Pt/Co_(SA)-N-C catalyst with significantly enhanced catalytic properties,i.e.,a mass activity(MA)of 0.719 A/mgPt at 0.9 ViR-free and a reduction of 24.2%in MA after a 20,000-cycles *** functional theory(DFT)calculations demonstrate that the enhanced electron interaction between Pt and Co_(SA)-N-C support decreases the dband center of Pt,which is in favor of lowering the desorption energy of ^(*)OH on Pt/Co_(SA)-N-C surface and accelerating the formation of H_(2)O,thus enhance the instinct activity of ***,the higher binding energy between Pt and Co_(SA)-N-C compared to Pt and C indicates that the migration of Pt has been suppressed,which theoretically explains the improved durability of Pt/Co_(SA)-*** work offers an enlightenment on constructing composite Pt-based catalysts with multiple active sites.

关键词： Fuel cells Oxygen reduction reaction Platinum Single-CoN_(4)-rich carbon support Metal-substrate interaction

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Total synthesis of lespedezavirgatol

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Science china chemistry 2010年第12期53卷 2547-2550页

作者： QI JinPing 1,DENG HongZhu 2 & cao DeRong 1 1 school of chemistry and {3. engineering,South china university of technology,Guangzhou 510640,china 2 school of Traditional Chinese Medicine,Southern Medical university,Guangzhou 510515,china school of chemistry and chemical {3. South China University of Technology Guangzhou China school of Traditional Chinese Medicine Southern Medical University Guangzhou China

Lespedezavirgatol,a novel 2-phenylbenzofuran compound which was isolated from Lespedeza virgata,was firstly synthesized from pyrogallic acid and 3.4-dimethoxyphenol as starting materials with 8 *** key steps for the total synthesis were the selective iodination at 3.position of 1,2-dimethoxy-4-methoxymethoxybenzene and the Sonogashira cross-coupling reaction between 4-iodo-2-methoxybenzene-1,3.diol and 2-ethynyl-3.4-dimethoxy-1-(methoxy-methoxy)-benzene.

关键词： 2-phenylbenzofuran lespedezavirgatol Sonogashira cross-coupling reaction

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Degradation of anthracene, pyrene and benzo[a]-anthracene in aqueous solution by chlorine dioxide

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Science china chemistry 2006年第6期49卷 565-572页

作者： LIU Jinquan1, HUANG Junli1, SU Liqiang2, cao Xiangyu1 & JI Ying1 1. school of Municipal and Environmental engineering, Harbin Institute of {3., Harbin 150090, china 2. school of chemistry and chemical engineering, Qiqihar university, Qiqihar 161006, china school of Municipal and Environmental engineering Harbin Institute of Technology Harbin China school of chemistry and chemical {3. Qiqihar University Qiqihar China

Polycyclic aromatic hydrocarbons (PAHs) constitute an important group of micropollutants, which are known to be mutagenic, carcinogenic and/or co-carcinogenic and relatively persistent in the environment. The effects of chlorine dioxide (ClO2) on the degradation of anthracene (ANTH), pyrene (PYR) and benzo[a]anthracene (BaA) in aqueous solution were investigated using high performance liquid chromatography (HPLC). In preliminary experiments, it was observed that ClO2 could remove these three PAHs effectively within a short time. Several factors including reaction time, the concentration of ClO2 and pH of the reaction mixture influencing the degradation ratio of PAHs have been studied by batch experiments. The results showed that the degradation ratio of PAHs was affected by reaction time and the concentration of ClO2 instead of pH. The degradation ratio of ANTH, PYR and BaA could reach their maximum as approximately 99.0%, 67.5% and 89.5%, respectively, under the condition as follows: reaction time 3., 60 and 120 min, the concentration of ClO2 0.1, 0.4 and 0.5 mmol·L-1, and pH 7.2. ANTH was selected as the representative to study the reaction mechanism with ClO2. The oxidation products formed in the reaction of ANTH with ClO2 were tentatively identified by gas chromatography-mass spectrometry (GC-MS), and the results showed that the main product was 9, 10-anthraquinone, which could be biodegraded more easily and quickly than ANTH. Through analyzing the reaction properties of ANTH and ClO2, the possible pathway for the ANTH-ClO2 reaction was proposed based on the theory of single electron transfer (SET).

关键词： chlorine dioxide, anthracene, pyrene, benzo[a]anthracene, degradation, reaction mechanism.

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Er^(3.)-Yb^(3.) codoped borosilicate glass for optical thermometry

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Science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 848-851页

作者： FENG ZhiQing1,BAI Lan2,cao BaoSheng1,GONG LiDong3.& DONG Bin1,4 1 school of Science,Dalian Nationalities university,Dalian 116600,{3. 2 College of Electromechanical & Information engineering,Dalian Nationalities university,Dalian 116600,{3. 3.school of chemistry and chemical engineering,Dalian 116029,{3. 4 Institute of Physics,Chinese Academy of Sciences,Beijing 100190,{3. school of Science Dalian Nationalities University Dalian China College of Electromechanical & Information engineering Dalian Nationalities University Dalian China school of chemistry and chemical {3. Dalian China Institute of Physics Chinese Academy of Sciences Beijing China

Infrared to green up-conversion emissions centered at the wavelengths of about 524 and 550 nm of the Er3.-Yb3. codoped borosilicate glass are recorded,using a 978 nm semiconductor laser diode(LD) as an excitation *** fluorescence intensity ratio(FIR) of the green up-conversion emissions at about 524 and 550 nm in the Er3.-Yb3. codoped borosilicate glass has been studied as a function of temperature over the temperature range of 295-873.*** maximum sensitivity and the temperature resolution derived from the FIR of the green up-conversion emissions are approximately 0.003. K-1 and 0.2 K,*** is demonstrated that the prototype optical temperature sensor based on the FIR technique from the green up-conversion emissions in the Er3.-Yb3. codoped borosilicate glass plays a major role in temperature measurement.

关键词： Er3.-Yb3. codoped optical temperature sensor fluorescence intensity ratio

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Simple substituents make big differences in photophysical performances of 2,1,3.benzothiadizole-conjugated spiropyrans

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Chinese Journal of chemical engineering 2024年第8期72卷 53-59页

作者： Xiaoming Zhu Yunting Liu Mingyue cao Guangle Niu State Key Laboratory of Crystal Materials Shandong UniversityJinan 250100China school of chemistry and chemical {3. Beijing Institute of TechnologyBeijing 100081China

Developing multifunctional spiropyran dyes is of particular importance in diverse *** the present study,we synthesized two 2,1,3.benzothiadiazole-conjugated spiropyrans(BT-SP-NO2and BTSP-NMe2)with distinct *** donor-acceptor-structured spiropyrans exhibited typical twisted intramolecular charge transfer features and strong emissions in low-polarity solvents with fluorescence quantum yields(QYs)of up to 90.7%.Like traditional spiropyrans,the electron-acceptor-substituted BT-SP-NO2exhibited excellent photochromic behavior under multiple alternating UV—Vis irradiation,while the electron-donor-substituted BT-SP-NMe2was an acidochromic *** addition,the substituent groups distinctly affected the packing modes of these spiropyrans in the solid ***-NMe2showed a much stronger solid-state emission(QY of 59.0%)than ***,these two dyes were utilized as biocompatible probes for the specific light-up imaging of lipid droplets.

关键词： Spiropyran 2,1,3.Benzothiadiazole Photochromism Fluorescent dye Fluorescence imaging

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Temperature-controlled ionic liquid dispersive liquid phase microextraction combined with ultra-high-pressure liquid chromatography for the rapid determination of triclosan,triclocarban and methyl-triclosan in aqueous samples

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Science china chemistry 2010年第12期53卷 2600-2607页

作者： GUO JieHong 1,2,LI XingHong 2,cao XueLi 1,QU Lei 2,3.HOU DeKun 2 & XU XiaoBai 2 1 school of chemical and Environmental {3.,Beijing technology and Business university,Beijing 100048,china 2 State Key Laboratory of Environmental chemistry and Eco-toxicology Research Center of Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,china 3.Zhengzhou university,Zhengzhou 450001,china school of chemical and Environmental engineering Beijing Technology and Business University Beijing China State Key Laboratory of Environmental chemistry and Eco-toxicology Research Center of Eco-Environmental Sciences Chinese Academy of Sciences Beijing China Zhengzhou university Zhengzhou China

As extraction solvents,ionic liquids have green *** this study,an environmentally benign analytical method termed temperature-controlled ionic liquid dispersive liquid phase microextraction (TIL-DLME) combined with ultra-highpressure liquid chromatography (UHPLC)-tunable ultraviolet detection (TUV) was developed for the pre-concentration and determination of triclosan (TCS),triclocarban (TCC) and methyl-triclosan (M-TCS) in water *** parameters that may affect extraction efficiencies were examined and optimized,including the types and amount of ionic liquids,volume of the diluent,heating temperature,cooling time,salt effect and pH *** the optimum conditions,linearity of the method was observed in the ranges of 0.0100-100 μgL-1 for TCS and M-TCS,and 0.00500-50.0 μgL-1 for TCC with correlation coefficients (r2) > *** limits of detection (LODs) ranged from 1.15 to 5.3. *** in domestic water and TCC in reclaimed water were detected at the concentrations of 1.01 and 0.126 μgL-1,*** spiked recoveries of the three target compounds in reclaimed water,irrigating water,waste water and domestic water samples were obtained in the ranges of 68.4%-71.9%,61.6%-87.8%,58.9%-74.9% and 64.9%-92.4%,*** with the previous dispersive liquid-liquid microextraction method (DLLME) about the determination of TCS,TCC and M-TCS,this method is not only more environmentally friendly but also more sensitive.

关键词： ionic liquid temperature-controlled ionic liquid dispersive liquid phase microextraction UHPLC aqueous samples

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Access to advanced sodium-ion batteries by presodiation:Principles and applications

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Journal of Energy chemistry 2024年第5期92卷 162-175页

作者： Shihao Zhang Ruoyu cao Xiangjun Pu Along Zhao Weihua Chen Chunhua Song Yongjin Fang Yuliang cao College of chemistry and Molecular Sciences Hubei Key Laboratory of Electrochemical Power SourcesWuhan UniversityWuhan 430072HubeiChina College of chemistry&Green Catalysis Center Zhengzhou UniversityZhengzhou 450001HenanChina Shenzhen Janaenergy techonulogy Co. Ltd.Shenzhen 518000GuangdongChina school of chemistry and chemical {3. Jiangsu University of TechnologyChangzhou 213001JiangsuChina Zonergy Corporation NO.68 Fucang RoadYantan DistrictZigong 643030SichuanChina

Sodium-ion batteries(SIBs)are expected to offer affordability and high energy density for large-scale energy storage ***,the commercial application of SIBs is hurdled by low initial coulombic efficiency(ICE),continuous Na loss during long-term operation,and low sodium-content of cathode *** this scenario,presodiation strategy by introducing an external sodium reservoir has been rationally proposed,which could supplement additional sodium ions into the system and thereby markedly improve both the cycling performance and energy density of *** this review,the significance of presodiation is initially introduced,followed by comprehensive interpretation on technological properties,underlying principles,and associated approaches,as well as our perspectives on present inferiorities and future research ***,this contribution outlines a distinct pathway towards the presodiation methodology,of significance but still in its nascent phase,which may inspire the targeted guidelines to explore new chemistry in this field.

关键词： Presodiation Increased coulombic efficiency High reversible capacity Sodium ion batteries

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Synergistic effect of Co and Co_(6)Mo_(6)C for electroreduction of nitrate to ammonia on Co-MOF derived Co_(6)Mo_(6)C/Co/NC

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Nano Research 2024年第7期17卷 5807-5816页

作者： Xinyan Wang Yue cao Yan Hai Xiaoman Li Min Luo State Key Laboratory of High-efficiency Utilization of Coal and Green chemical engineering School of Chemistry and Chemical EngineeringNingxia UniversityYinchuan 750021China

Electrocatalytic nitrate reduction reaction(e-NO_(3.RR)offers a promising alternative method for nitrogen cycling and ammonia(NH3.production under ambient ***,the method is still in the dilemma of lowering the reaction overpotential and increasing the reaction *** successfully developed the composition-adjustable Co_(6)Mo_(6)C/Co/N-doped carbon(NC)catalysts by in situ carbonization of Co-based metal-organic framework(MOF)with the constrained phosphomolybdic *** adjusting the ratio of Co0 and Co_(6)Mo_(6)C,Co_(6)Mo_(6)C/Co/NC-3.could satisfy both NO_(3.−conversion at low potential and NH_(x)hydrogenation,and synthesize ammonia efficiently through the synergistic effect of Co0 and Co_(6)Mo_(6)*** achieved an ammonia yield rate as 123..2μg·h^(−1)·mgcat^(−1)and Faradaic efficiency of NH4+93.6%at−0.3. V *** hydrogen electrode(RHE).Importantly,density functional theory(DFT)calculations and experimental results have demonstrated for the first time the excellent adsorption of nitrite(NO_(2)^(−))by the Mo sites of Co_(6)Mo_(6)C during e-NO_(3.RR,avoiding the undesirable accumulation of NO_(2)^(−).

关键词： synergistic effect nitrate electroreduction Co_(6)Mo_(6)C ammonia synthesis

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Sustainable production of high-energy-density jet fuel via cycloaddition reactions

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Journal of Energy chemistry 2024年第8期95卷 712-722,I0016页

作者： Yan-Cheng Hu Yingying Zhao Ning Li Jing-Pei cao school of chemical engineering and {3. China University of Mining and TechnologyXuzhou 221116JiangsuChina school of Education Science Jiangsu Normal UniversityXuzhou 221116JiangsuChina CAS Key Laboratory of Science and technology on Applied Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina

Developing an energy supply-chain based on renewable biomass holds great potential to build a low carbon ***-energy-density(HED)jet fuel,featuring unique fused/strained cycloalkanes,is of great significance for volume-limited military aircrafts,as their high density and combustion heat can extend flight duration and increase the ***,the exploration of biomass-based routes towards HED fuel has drawn much attention over the past *** reaction features rapid construction of various carbocycles in an atom-and step-economical *** elegant strategy has been widely applied in the manufacture of sustainable HED *** we carefully summarize the progress achieved in this fascinating area and the review is categorized by the cycloaddition patterns including[4+2],[2+2],[4+4],and[2+1]***,the energy densities of the as-prepared biofuels and petroleumbased fuels(conventional Jet-A and advanced JP-10)are also *** review will provide important insights into rational design of new HED fuel with different ring-types/sizes and inspire the chemists to turn those literature studies into practical applications in military field.

关键词： High-energy-density fuel Biomass-based chemicals Cycloaddition Cycloalkanes Catalysis

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