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Silylated and acetylated β-cyclodextrins for gas chromatographic stationary phases

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Journal of Central South university of Technology 2001年第4期8卷 239-243页

作者： TANG Ke wen 1,2.,YI Jian ming 2.ZHOU Chun shan 1,ZHONG Shi an 1 (1. college of {2. and chemical engineering, Central South university, Changsha 410083, China 2. college of chemistry and chemical engineering, Yueyang Normal university college of chemistry and {2. engineering Central South University Changsha China college of chemistry and {2. engineering Yueyang Normal University Yueyang China

Two new chiral stationary phases, 2.3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2.6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means of infrared and NMR spectra. Capillary columns were coated with the two stationary phases by dynamic method. The chromatographic properties, and enantiomers separation, such as ketone, esters, alcohols and olefines, were investigated on the silylated and acetylated β cyclodextrin stationary phases. The experimental results show that the silylated and acetylated β cyclodextrins are suitable to be used as capillary gas chromatographic stationary phases, the relative polarity of DATBCD and DTABCD stationary phases is respectively 4143 and 392., the column efficiencies are respectively 3084 and 4198, and DATBCD is of stronger enantioselectivity than DTABCD, capacity factor of the first eluted enantiomer ( k 1) and separation factor(α)of α phenylethanol on DATBCD stationary phase are respectively 8.2. and 1.019.

关键词： capillary gas chromatography silylated and acetylated β-cyclodextrins enantiomeric separation

Adsorption and corrosion inhibition behavior of imidazole on cobalt electrodes studied by SERS and electrochemical methods

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Science China chemistry 2005年第6期48卷 497-503页

作者： GU Wei1, LIU Guokun2. REN Bin2. WU Deyin2. GU Renao1 & TIAN Zhongqun2.1. Department of chemistry, college of chemistry and chemical engineering, Suzhou university, Suzhou 2.5006, China 2. State Key Laboratory for Physical chemistry of Solid Surfaces and Department of chemistry, college of chemistry and chemical engineering, Xiamen university, Xiamen 361005, China Department of chemistry College of Chemistry and Chemical Engineering Suzhou University Suzhou China State Key Laboratory for Physical chemistry of Solid Surfaces and Department of chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen China

The interaction of imidazole with Co electrodes in an electrochemical system was studied by surface-enhanced Raman scattering (SERS) and electrochemical methods. The SER spectra of Co in an imidazole solution as a function of the applied potential were analyzed and the assignment of the Raman bands was made. It was found that there were three kinds of sur-face species on the Co surface in different potential regions and they were interchangeable de-pending on the potential. In a relatively negative potential region (?1.2.to ?0.9 V), imidazole was adsorbed on the surface and its orientation might change from a vertical configuration via the N-end of the pyridine ring to a tilted configuration via the C2.N3 double bond. In a more positive potential region (?0.8 to ?0.7 V), the SERS signal from the adsorbed imidazole weakened and finally disappeared, meanwhile the signal from the Co and imidazole complex strengthened gradually. At the open circuit potential (?0.6 V), we detected very strong bands from the Co ox-ides. By comparing the Tafel curves of the Co electrode in the solution without and with imidazole, we found that imidazole has a marked effect on the corrosion inhibition of the Co electrode. This result demonstrates that we may be able to reveal the complicated interaction of surface species with metal surface at the molecular level by combining the SERS and electrochemical methods.

关键词： cobalt, imidazole, inhibition, surface-enhanced Raman spectroscopy, Tafel plot.

Resolution of α-cyclohexyl-mandelic acid enantiomers by two-phase (O/W) recognition chiral extraction

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Science China chemistry 2007年第6期50卷 764-769页

作者： TANG KeWen1,2. ZHANG GuoLi2. HUANG KeLong2. LI Yuanjian3 & YI JianMin1,2.1 Department of chemistry and chemical {2., hunan Institute of Science and Technology, Yueyang 414000, China 2.college of chemistry and chemical {2., Central South university, Changsha 410083, China 3 college of Pharmaceutical Science, Central South university, Changsha 410078, China Department of chemistry and chemical {2. Hunan Institute of Science and Technology Yueyang China college of chemistry and {2. engineering Central South University Changsha China college of Pharmaceutical Science Central South University Changsha China

This paper presents a new chiral separation technology:two-phase(O/W)recognition chiral *** behavior of alpha-cyclohexyl-mandelic acid enantiomers was studied in the extraction system with D(L)-isobutyl tartrate in 1,2.dichloroethane organic phase and beta-CD derivatives in aqueous phase,and the influence of the kind and concentration of extractant and pH on extraction performance was *** experimental results indicate that two-phase(O/W)recognition chiral extraction is of strong chiral separation ***-^-CD,HE-beta-CD and Me-beta-CD have higher recognition ability for S-CHMA than that for R-CHMA,among which HP-beta-CD has the strongest ability;whereas,D-isobutyl tartrate has reversed recognition ability for *** the extraction system containing HP-beta-CD and D-isobutyl tartrate,e.e.% of S-CHMA in aqueous phase reached 2..6% by one stage extraction,and the distribution ratio for R-CHMA(k_R)and for S-CHMA(k_S)and separation factor(alpha)are 2.44,0.89 and 2.49,***,pH and concentration of extractant have great effects on chiral separation ***-phase(O/W)recognition chiral extraction has great significance for preparative separation of racemic compounds.

关键词： two-phase(W/0)recognition chiral extraction alpha-cyclohexyl-mandelic acid enantiomers

Hydroisomerization of n-heptane over bimetal-bearing H_3PW_(12.O_(40) catalysts supported on dealuminated USY zeolite

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Science China chemistry 2008年第2期51卷 120-127页

作者： WEI RuiPing1,2. GU YanBo1 & WANG Jun1 1 State Key Laboratory of Materials-Oriented chemical engineering, {2. of chemistry and chemical engineering, Nanjing Uni- versity of Technology, Nanjing 2.0009, China 2.{2. of chemistry and chemical engineering, Southeast university, Nanjing 2.1189, China State Key Laboratory of Materials-Oriented chemical engineering College of Chemistry and Chemical EngineeringNanjing University of TechnologyNanjing 210009China college of chemistry and {2. engineering Southeast UniversityNanjing 211189China

The bimetal-bearing (CePt or LaPt) 12.tungstophosphoric acid (H3PW12.40 (PW)) catalysts supported on dealuminated USY zeolite (DUSY) were prepared by impregnation and characterized by XRD, BET, IR, and H2.chemisorption. Their catalytic activities were tested in the hydroisomerization of n-heptane with a continuous atmospheric fixed-bed reactor. After the steam treatment combined with the acid leaching, as well as the supporting with PW and the bimetals, the DUSY support retains the Y zeolite porosity and the PW well keeps its Keggin structure in catalysts. The doping of Ce into the catalysts enhances the dispersion of Pt on the catalyst surface. The Pt-bearing PW catalysts doped with Ce or La, especially Ce, exhibit much higher catalytic activity and selectivity than the catalysts without dopants at lowered reaction temperatures. At the optimal reaction conditions, i.e., the reaction temperature of 2.0℃ and WHSV of 1.4 h1, the catalyst with a Pt loading of 0.4%, PW loading of 10% and a molar ratio of Ce to Pt of 15:1 shows a conversion of n-heptane of 70.3% with a high selectivity for isomerization products of 94.1%.

关键词： hydroisomerization of n-heptane bimetal catalyst heteropoly acid USY platinum

A thin-layer spectroelectrochemical study of 3,3',5,5'-tetramethylbenzidine at SnO_2.F film optically transparent electrode

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Science China chemistry 2004年第4期47卷 267-275页

作者： JIAO Kui1, YANG Tao2.& NIU Shuyan1,2.1. college of chemistry and Molecular {2., Qingdao university of Science and Technology, Qingdao 2.6042. China 2. college of chemistry and chemical engineering, Ocean university of China, Qingdao 2.6003, China Correspondence should be addressed to Jiao Kui college of chemistry and Molecular {2. Qingdao University of Science and Technology Qingdao China college of chemistry and {2. engineering Ocean University of China Qingdao China

The electrooxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) is dependent on the pH value of Britton-Robinson (B-R) buffer solution. In this work, the electrooxidation behavior of TMB was investigated with a SnO2.F film optically transparent thin-layer spectroelectrochemical cell. TMB underwent one two-electron electrooxidation process in the pH range from 2.0 to chemical reaction to yield an azo compound. Several spectroelectrochemical techniques, such as thin-layer cyclic voltammetry, thin-layer cyclic voltabsorptometry, thin-layer potential-controlled electrolysis absorptometry, thin-layer single-potential-step chronoabsorptometry, thin-layer dou-ble-potential-step chronoabsorptometry, thin-layer single-potential-step open-circuit relaxation chronoabsorptometry, were applied to this investigation. The formal potential E0’ and the electron transfer number corresponding to the electrooxidation of TMB in B-R buffer solution, and the reaction rate constant of the subsequent chemical reaction were determined.

关键词： 3,3′,5,5′-tetramethylbenzidine tin oxide film optically transparent electrode thin-layer spectroelectro-chemistry electrooxidation

Preparation of well-defined polystyrene/silica hybrid nanoparticles by ATRP

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Science China chemistry 2008年第1期51卷 51-57页

作者： OU BaoLi1,2.LI DuXin2.1 college of chemistry and {2. engineering,hunan university of Science and Technology,Xiangtan 4112.1, China 2.State Key Laboratory of Powder Metallurgy,Central South university,Changsha 410083, China college of chemistry and {2. engineering Hunan University of Science and Technology Xiangtan China State Key Laboratory of Powder Metallurgy Central South University Changsha China

Immobilization of the atom transfer radical polymerization (ATRP) macroinitiators at the silica nanoparticle surfaces was achieved through surface modification with excess toluene-2.4-diisocynate (TDI), after which the residual isocyanate groups were converted into ATRP macroinitiators. Structurally well-defined polystyrene chains were grown from the nanoparticle surfaces to yield individual particles composed of a silica core and a well-defined, densely grafted outer polystyrene by ATRP, which was initiated by the as-synthesized silica-based macroinitiator. FTIR, NMR and gel permeation chro-matography (GPC) were used to characterize the polystyrene/silica hybrid particles.

关键词： silica nanoparticles surface modification atom transfer radical polymerization polystyrene hybrid particle

Preparation of polystyrene/silica nanocomposites by radical copolymerization of styrene with silica macromonomer

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Science China chemistry 2007年第3期50卷 385-391页

作者： OU BaoLi1,2.& LI DuXin2.1 college of chemistry and {2. engineering, hunan university of Science and Technology, Xiangtan 4112.1, China 2.State Key Laboratory of Powder Metallurgy, Central South university, Changsha 410083, China college of chemistry and {2. engineering Hunan University of Science and Technology Xiangtan China State Key Laboratory of Powder Metallurgy Central South University Changsha China

A two-stage process has been developed to generate the silica-based macromonomer through surface-modification of silica with polymerizable vinyl groups. The silica surfaces were treated with excess 2.4-toluene diisocynate (TDI), after which the residual isocyanate groups were converted into polymerizable vinyl groups by reaction with hydroxypropylacrylate (HPA). Thus, polystyrene/silica nanocomposites were prepared by conventional radical copolymerization of styrene with silica macromonomer. The main effecting factors, such as ratios of styrene to the macromonomer, together with polymerization time on the copolymerization were studied in detail. FTIR, DSC and TGA were utilized to characterize the nanocomposites. Experimental results revealed that the silica nanoparticles act as cross-linking points in the polystytene/silica nanocomposites, and the glass transition temperatures of the nanocomposites are higher than that of the corresponding pure polystyrene. The glass transition temperatures of nanocomposites increased with the increasing of silica contents, which were further ascertained by DSC.

关键词： silica nanoparticles surface modification styrene radical copolymerization nanocomposites

Synthesis and Characterization of Polyurethane/Poly (Urethane Modified Bismaleimide-Bismaleimide) IPNs

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Chinese chemical Letters 2000年第6期11卷 525-526页

作者： Yuan Li CAI Peng Sheng LIU (college of chemistry and {2. engineering, Xiangtan university, hunan 411105) college of chemistry and {2. engineering Xiangtan University

PU/P(UBMI-BMI) IPNs with excellent thermal stability and mechanical properties were synthesized and characterized. The interpenetrating occurs in the hard segment domains of PU, which leads to enhancement of hydrogen ... 详细信息

关键词： PU/P(UBMI-BMI) IPNs synthesis characterization

Insight into the development of electrolytes for aqueous zinc metal batteries from alkaline to neutral

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Chinese chemical Letters 2024年第2期35卷 232-241页

作者： An Duan sha Luo Wei Sun School of Materials and Energy University of Electronic Science and Technology of ChinaChengdu 611731China

Aqueous zinc metal batteries are considered as promising candidates for next-generation electrochemical energy storage devices,especially for large-scale energy storage,due to the advantages of high-safety,high energy density and low *** the bridge connecting cathode and anode,electrolyte provides a realistic operating *** alkaline and neutral aqueous zinc metal batteries,issues associated with electrolyte and anode are still *** this review,we reveal the development and evolution of electrolytes for aqueous zinc metal batteries from alkaline to neutral via the description of fundamentals and challenges in terms of comparison and *** also elaborate the strategies in electrolytes regulation and highlight the basic roles and progresses in additives engineering.

关键词： Aqueous electrolytes Zinc metal batteries pH-dependent chemistry Electrolyte regulation Additives engineering