Table of Content

24 August 2003, Volume 24 Issue 8

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Articles

Formation of Silver Nanoprisms and Their Optical Properties

HE Rong, QIAN Xue-Feng, YIN Jie, ZHU Zi-Kang, WANG Hai-Lin

2003, 24(8):  1341-1345. 

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Silver nanoprisms have been prepared by a soft solution approach under microwave irradiation from the solution of silver nitrate(AgNO₃) in the presence of poly(N-vinyl-2-pyrrolidone) without any other reducing agent.The reaction process was followed by X-ray powder diffraction, TEMand UV-Vis spectroscopy.The results showed that silver nanoprisms were formed from the spherical nanoparticles.Most of them were triangular(edge length 50-100 nm) or truncated triangular nanoprisms and two distinct quadrupole plasmon resonances in UV-Vis spectra were observed.With reaction progress, the colloid solution with a interesting color was obtained.The influences of the PVP/AgNO₃mass ratio, solid content and inorganic precursor on the optical properties and morphology of silver nanoparticles were investigated.

Influence of Rare Earth Irons on the Molecular Recognition Between Calmodulin and Monoclonal Antibody

LI Wei-Guo, QI Chao, DU Li, LIU Li-Yan, ZHAO Da-Qing

2003, 24(8):  1346-1350. 

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The molecular recognitions between monoclonal antibody 2C3 and calmodulin saturated with different metaLIons(La³⁺, Eu³⁺, Yb³⁺and Ca²⁺) were investigated by the enzyme linked immunosorbent assay(ELISA) and labeled fluorescence spectroscopy.The results indicate that after binding with different metaLIons, the calmodulin undergoes different conformational changes, which have a significant effect on its recognition ability to a metaLIon induced conformation-specific monoclonal antibody.The dissociation constants between the antibody and the calmodulin saturated with La³⁺, Eu³⁺, Yb³⁺are (26.8±2.5), (21.8±3.4) and (64.8±5.1) nmol/L, respectively, while the dissociation constants between the antibody and Ca²⁺-CaMor apoCaMare (157±4.2) and (177.2±2.8) nmol/L, respectively.This result indicates lanthanide-induced conformational changes of calmodulin are not similar with that induced by calcium, which maybe account for the facts that lanthanide and calcium ions lead to different effects on the regulating function of calmodulin in biological systems.

A Novel Method for Preparing Mesoporous Silica Pillared Montmorillonite Material and Its Structure Characterization

ZHOU Chun-Hui, LI Qing-Wei, GE Zhong-Hua, LI Xiao-Nian, NI Zhe-Ming

2003, 24(8):  1351-1355. 

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The mesoporous silica pillared clays, with porous montmorillonite(MMT) heterostructures, were synthesized by pillaring and template-assembly techniques.The purified MMTis modified by cetyltrimethylammonium bromide(CTAB).Mixtures of the modified MMT, dodecylamine(DDA) and tetraethylorthosilicate(TEOS) at MMT/DDA/TEO Smolar ratios of 1∶20∶150 were allowed to react for₈h.Then the resulted intercalates were centrifuged and dried in air.Finally after calcination at 540 ℃ for {4 h} to remove the organic templates, the novel silica porous MMTheterostructures(PMHs) were obtained.The resulted PMHs were characterized by XRD, TG, FTIRand N₂adsorption-desorption isotherms.The results indicate that the PMHs possess mesopore(average pore size of 2.17 nm), super-gallery height of 2.75 nm, a large BETspecific surface area of 821.6m₂/g and high thermal stability up to 800℃. Through changing the chain length of neutral amine used, the adjustment of pore and gallery height of PMHs has been explored.The mechanism of pore formation through gallery template-assembly was postulated, and the higher thermal stability of PMHs was ascribed to uniformity of pillars.

Preparation and Characterization of NASICON Material by Sol-Gel Method

ZHANG Shuang, QUAN Bao-Fu, ZHAO Zhi-Yong, ZOU Yong-Cun, HE Yue-Hua, CHEN Li-Hua

2003, 24(8):  1356-1359. 

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Solid electrolyte NASICONmaterial has been synthesized by Sol-Gel method.The structure and composition were determined by XRD, IRabsorption spectra, Raman spectra and NMR.The superionic electric characteristic was determined by conductivity measurement.The experimental results show that the powders sintered at 900 ℃ possess better properties compared with those of the samples sintered at 700, 800 and 1100 ℃.

Synthesis and Properties of Tetrabromo-2,3-naphthalocyanine Lead(Ⅱ)

HE Chun-Ying, WU Yi-Qun, SONG Ying-Lin, WANG Yu-Xiao, ZUO Xia

2003, 24(8):  1360-1365. 

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Tetrabromo-2,3-naphthalocyanine lead(PbNcBr₄) was synthesized in the presence of 1, 8-diazabicycloundec-7-ene(DBU) and its electronic absorption spectra, thermal stability, optical limiting property and the effect of bromine substituent on the above properties were investigated.There is one strong Q-absorption band in nearinfrared region.Bromine substituent attached to outer Nc ring results in the Q-band of PbNcBr₄shifting to the blue compared to the complex unsubstituted.The polarity of solvents have influences on the electronic absorption spectra greatly< The complex shows high thermal stabilities and appears to be more stable in N₂(the onset temperature 504.6 ℃) than in O₂(the onset temperature 326.8 ℃).The thermal stabilities decrease on account of bromine substituent attached to outer Nc ring and declining extent changes with the varieties of atmosphere(decreased by 175℃ in N₂, 25 ℃ in O₂).Decomposition mechanisms differ according to the varieties of atmosphere with one step in O₂and multi steps in N_2.At a relatively high linear transmittance of 88%, the limiting threshold is 148mJ/cm², the clamped fluence is 332 mJ/cm², and the damage fluence is about 3J/cm². The optical limiting behavior of PbNcBr₄is better than that of C₆₀whose limiting threshold is above 240 mJ/cm²with a linear transmittance of 70%. It can be regarded as a new kind of materials which has a better optical limiting property.

Hydrothermal Synthesis and Structure of A Novel [Co(phen)(μ₃-md)]_n

LI Chuan-Bi, ZHANG Li-Juan, SUN Ying-Hua, LI Yong, WANG Tie-Gang, XU Ji-Qing 

2003, 24(8):  1366-1367. 

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Anovel 1-Dcompound, [[Co(phen)(μ₃-md)]_n] n, was hydrothermally synthesized and characterized by single crystal X-ray diffraction analysis, elemental analysis and IRspectra.This compound was crystallized in monoclinic system, space group P₂/C with a=0.8329(18) nm, b=1.04135(11) nm, c=1.8348(5) nm, β=100.436(18)°, Dc=1.706 mg/cm³, R₁= 0.0379, wR₂=0.0866. The 1-Ddouble-chain structure of the title compound is formed by benzene-1,3-dicarboxylate connected with three Co atoms.

Studies on GC/MS and ESI/MS/MS Screening of MMAUria with Stable Isotope Labeling Method

ZHAO Ji-Yuan, WANG Yi-Ming, LUO Guo-An, ZHANG Ting, WU Jian-Xin, WANG Li-Wen

2003, 24(8):  1368-1372. 

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Early diagnosis of inborn errors of metabolism(IEM) is a challenging and undeveloped area in China.As one of the diseases with most frequency, methylmalonic aciduria(MMAUria) is studied by using GC/MSand ESI/MS/MSmethod.Information of almost all urinary metabolites can be obtained by GC/MSusing urease pretreatment and stable isotpe labeling.We also develop a way to analyze a urine sample in 2 minutes by ESI/MS/MS.Both the two methods have a good recovery.The combination of the two methods can not only be used for high-risk screening, but also for newborn screening.

Fabrication of Chemically-modified Electrode Containing Poly(allylamine)ferrocene Based on Sol-gel Technique and Its Electrocatalytic Oxidation of Ascorbic Acid

LI Ya-Zuo, ZHANG Su-Xia, LI Xiao-Fang, SUN Chang-Qing

2003, 24(8):  1373-1376. 

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The functional molecular poly(allylamine)ferrocene was modified on the surface of glassy carbon electrode by the sol-gel technique.The electrochemical behavior of the modified electrode was characterized by cyclic voltammetry in detail.The results obtained show that the modified electrode exhibited an excellent electrocatalytic response to the oxidation of ascorbic acid.The anodic overpotential was reduced by about 190 mVcompared with that obtained at a bare glassy carbon electrode for the oxidation of ascorbic acid.The modified electrode possesses several attractive features, such as simple preparation, fast response and so on.

A Novel Amperometric Immunosensor Based on Aggregation of Chitosan and CNBr-activated Alginate for Determining Schistosoma Japonicum

CHAO Xuan, HU Shun-Qin, SHEN Guo-Li, YU Ru-Qin

2003, 24(8):  1377-1380. 

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Anovel schistosoma japonicum(Sj) imunnosensor based on aggregation of chitosan and CNBr-activated alginate is developed.The complex formed by CNBr-activated alginate and antibody is aggregated on the surface of the paraffin-graphite-chitosan electrode by electrostatic adsorption(coacervation).The concentration of SjAg can be detected by determining the redox current of o-aminophenol oxidized by H₂O₂in the presence of HRP.The electrode can be reused by simple treatment.Moreover, the imunnosensor shows some improved performances including high sensitivity, selectivity and less non-specific adsorption.The sensor exhibits a linear response to SjAg in the concentration range from 0.64 to 40 μg/mL.The sensor was applied to the determination of SjAg in rabbit serum with satisfactory results.

Electronic Nose for the Determination of Formaldehyde in Air

ZHANG Liang-Yi, WEN Li-Jing, ZHOU Feng, ZHANG Song, YANG Peng-Yuan

2003, 24(8):  1381-1384. 

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This paper reports a portable electronic nose(e-nose) for the selective determination of formaldehyde in the presence of interference gases.The e-nose is composed of an array of four sensors, a signal regulating circuit, an electronic olfactory and a display.The fuzzy neural network(FNN) is applied to the analysis of the sensor responses.The reported results are satisfied with a pass rate of 81.3% within the permitted relative error in the mass concentration range of 0.001-0.25 mg/Land have no recognition error for the formaldehyde in the presence of interference gases.The enose is reliable for the recognition and determination of formaldehyde concentration in air.

Electrochemiluminescence of the Bentonite Modified Carbon Paste Electrode and Its Analytical Application

ZHENG Xing-Wang, ZHANG Zhu-Jun, WANG Qi

2003, 24(8):  1385-1389. 

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In this paper, it was found that the isoniazide could be effectively preconcentrated onto the carbon paste electrodes doped with bentonite.Then, based on the medium exchange and its sensitizing effect of isoniazide for the weak ECLsignal of electrooxidation luminol, the isoniazide could be sensitively and selectively detected witHECLmethod.In addition, it was also found that the blank ECLsignal of electrooxidation luminoLItself, compared to the unmodified CPE, was effectively decreased on the surface of bentonite modified CPE.In this case, a more higher ratio of the ECLsignal to the noise for detecting isoniazide with this chemically modified CPEwas obtained.Based on these findings, a more sensitive and selective ECLmethod for the determination of isoniazide was developed.At the same time, a new concept, to improve the sensitivity of luminol ECLsystem, based on using chemically modified CPE, was also first developed in this paper.Under the selecting experimental conditions, the relative ECLintensity was linear with isoniazide concentration in the range of 5.0×10^-9-8.0×10^-7mol/L.The correlation coefficient is 0.9984.

Studies on an Electrochemical DNA Biosensor Based on Gold Nanoparticle-labeled DNA Probe

CAI Hong, WANG Yan-Qin, HE Pin-Gang, FANG Yu-Zhi

2003, 24(8):  1390-1394. 

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An electrochemical detection method for the analyzing sequence-specific DNAusing gold nanoparticle labeled oligonucleotide DNAprobes has been developed.Target DNAwere covalently immobilized on a glass carbon electrode and incubated with gold nanoparticle-labeled DNAprobes, containing a complementary sequence.Binding events were monitored by electrochemical signal of gold nanoparticle hybridized to the electrode surface.The signal difference permits to distinguish the match of two perfectly complementary DNAstrands from the near-perfect match where just one base pair was wrong.The sensitivity of this electrochemical DNAbiosensor has been detected and a detection limit of 1.0 nmol/Lof oligonucleotides was achieved.

Studies on the Interaction of Daunomycin and the Specific Sequence of DNA

CHENG Gui-Fang, ZHANG Dong-Mei, DING Min, QU Hai-Yun, HE Pin-Gang, FANG Yu-Zhi

2003, 24(8):  1395-1399. 

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On the ground of UV-spectrophotometry and UV-spectroelectrochemistry, the interaction of daunomycin(DNR) and specific sequence of DNAhas been investigated.As the results obtained in this paper, DNRcan react with the sequence of oligonucleotide which is CpG, ApGand ApCsuccessively; the sequence of base pairs of double helix of DNAwhich are intercalated by DNRare (CpG)₂, (TpG)(CpA) and (CpT)(ApG).An important conclusion has been gained in this paper that if Gbases were not pairing in the helix of DNA, the spectroelectrochemical characteristic of the adducts containing that kind of DNAand DNRwould exhibit a remarkable difference with those adducts consisting of DNRand normal DNA.It indicates that this characteristic can be used to detect and determine the DNAhelix which has one base unpaired or mispairing.The results obtained in this paper are of clinical and pharmacaLImportance.

A Novel pHElectrode Based on Titanium Nitride

LU Xu-Lin, YUAN Hong-Yan, XIAO Dan

2003, 24(8):  1400-1402. 

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Titanium nitride was recommended as pH-sensitive materials to fabricate pHsensors.The TiNelectrode studied in this paper showed a linear response in the pHrange of 11-14 with a response slope of -60 mV/pH.The correlation coefficient was 0.998.The response time of the electrode was about 1min.It exhibits some advantages over the glass pHelectrode in more rigid structure and better selectivity toward cations of alkali metals, effectively overcoming the interference of Na⁺in high pHsolution.No interferences from commonly accompanying cations and anions were observed.The electrode also showed a high stability and a good reproducibility.The potential drift was less than 2m Vas measured in pH 13.5 and 14 solution for 2h.When the electrode was alternately measured in the solution of pH13.5 and 14 solution, the relative standard deviation estimated for six measurements were about 0.27% and 0.29%, respectively.In addition, the electrode was performed excellently in corrosion medium containing F^-. The lifetime of the electrode was over₃months.

A Novel Microwave-assisted Extraction Method for Extracting Flavonoids from Radix et Caulis Acanthopanacis Senticosi

DING Lan, LI Yi, LI Min-Jing, LIU Zhong-Ying, ZHANG Han-Qi

2003, 24(8):  1403-1405. 

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In this studYANovel microwave-assisted extraction(MAE) device was presented.In this newly developed system, a 3/4 wavelength microwave resonance cavity was used as the microwave coupling device for replacing a traditional microwave oven.This device is used to extract flavonoids from Radix et caulis acanthopanacis senticosi.The effects of solvent concentration, microwave forward power and solvent uptake rate on the extraction yield of flavonoids were investigated by using orthogonal experimental design.The results show that the effects of the solvent(ethanol) concentration and solvent uptake rate on the extraction yield of flavonoids are very significant, the effect of the interaction of solvent concentration and solvent uptake rate is significant and the effects of the other factors are general.Under the optimal conditions of MAEthe extraction yield of flavonoids by this system is 46% higher than that by Soxhlet method.The RSDof the method was lower than 6%.

Preliminary Computer Simulation of Spatial Structure of SARS Coronavirus E-protein

CHEN Yan-Tao, LUO Zhong-Lin, DING Jian-Dong

2003, 24(8):  1406-1409. 

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The HPcoarse-grained model has been applied to study three-dimensional spatial structures of a protein via lattice Monte Carlo simulation, in which residues exhibit different hydropathical energies.Reversed HPmodel has also been introduced to deal with protein under a lipid environment.The simulation approach seems very efficient.Preliminary computer experiment has been performed to study E-protein which is believed in the envelope of SARS(Severe Acute Respiratory Syndrome) associated coronavirus.Coil-globule transition has been reproduced in E-protein under a completely aqueous or lipid environment.Heterogeneity of this 76-residue polypeptide is verified to be important.Aqueous environment results in a hydrophobic core and hydrophilic loops.In contrast, lipid environment makes central segment as bridge or loop linking two relatively hydrophilic marginal segments.

Total Synthesis of Natural Macrocyclic Diterpene (±)-Sinulariol-A

LI Shu-Hua, PENG Li-Zeng, ZHANG Tao, LI Yu-Lin

2003, 24(8):  1410-1413. 

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The total synthesis of natural macrocyclic diterpene (±)-Sinulariol-A(1), a marine cembraniol, starting from geranioLIs described.The key steps are the chromium-induced intramolecular cyclization of the ω-formyl-β-methoxycarbonylallyl halide 9, the phosphine-catalyzed Morita-Baylis-Hillman addition of methyl acrylate to aldehyde 5 and chlorination reaction of ester 7.The 14-membered ring cis-hydroxy ester 10was then underwent reduction with LiAlH₄to produce the title compound(±)-1 in 85% yield.

Studies on the Synthesis of Four Natural₁,7-Diarylheptanoids

LI Shao-Bai, LIU Yun-Gen, ZHU Ming-Zhao

2003, 24(8):  1414-1418. 

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Diarylheptanoids constitute a distinct group of metabolites of natural plant characterized by two aromatic rings linked by a linear seven aliphatic chain.There have been few reports on the biological activities of diarylheptanoids, most of which appearing in the areas of anti-inflammatory, anti-oxidative, superoxide scavenging and anti-hepatotoxic effects.Some of them are used as traditional medicine in Asia.Compounds 1 and 2 were firstly isolated from the rhizomes of Zingiber offical respectively.1-(3′,4′-Dihydroxyphenyl)-7-(4″-hydroxyphenyl)-4-hepten-3-one(4) was firstly isolated from the flowers of A.japonica.Herein, we report the synthesis of these four natural1,7-diarylheptanoids, 5-hydroxy-1-(4′-hydroxy-3′-methoxyphenyl)-7-(4″-hydroxyphenyl)-3-heptanone (1), 1-(4′-hydroxy-3′-methoxyphenyl)-7-(4″-hydroxyphenyl)hept-4-en-3-one (2)(Gingerenone C), 5-hydroxy-1-(3′,4′-dihydroxyphenyl)-7-(4″-hydroxyphenyl)-3-heptanone (3) and 1-(3′,4′-dihydroxyphenyl)-7-(4″-hydroxyphenyl)hept-4-en-3-one (4).And compounds 1, 2 and 4 were firstly synthesized.

Synthesis and Spectrum of Chiral Boc Protected Amino Acids Linked Porphyrins

ZHAO Xiao-Jing, RUAN Wen-Juan, ZHANG Yu-Ling, HAN Hua, ZHU Zhi-Ang

2003, 24(8):  1419-1423. 

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Meso-tetrakis(o-BocAlamido) porphyrin [H₂T(o-BocAla)APP, 1] and its zinc complex [ZnT(o-BocAla)APP, Zn-1, meso-tetrakis(o-BocThrmido)porphyrin [H₂To-ocAls)APP, and its zinc complex [ZnT(o-BocThr)APP, Zn-2 , meso-tetrakis(o-BocTyrmido) porphyrin [H₂T(o-BocTyr)APP, 3and its zinc complex [ZnT(o-BocTyr)APP, Zn-3] were synthesized and characterized by elemental analyses, FTIR, ¹HNMR, UV-Vis and CD.The FTIRspectra and ¹HNMR of these complexes were compared and discussed.The UV-Vis and CDspectra of complexes were also attributed and minutely discussed.Compared with ZnTPP, the bands of porphyrins 1, 2, 3 have visibly red-shifts.Obviously, the cotton signals of 1 and 2, 3 are opposite, maybe it was caused by hydroxyl group.

A Rapid Parallel Synthesis of₂-Amino-4H-imidazol-4-ones

DING Ming-Wu, SUN Yong, LIU Xiao-Peng

2003, 24(8):  1424-1426. 

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Fourteen unreported 2 -amino-4H-imidazol-4-ones 4 were rapidly synthesized bYANew parallel synthetic method, which included aza-Wittig reaction of iminophosphorane₁with phenyLIsocynate to give carbodiimide 2 and subsequent reaction of 2 with various amines in a parallel fashion.The structure of compound 4 was confirmed by means of ¹HNMR, MSand IR.The configuration of compound 4b was determined as in Zform since the coupling constant ³J( ¹³C, ¹H) between the carbonyl carbon and the olefinic hydrogen was 5.6 Hz.

One-pot Synthesis of the O-(3-Diosgenin) O′-[5′-(3′-Azido- 3′-deoxythymidine)]-H-phosphonate

XIAO Qiang, JU Yong, ZHAO Yu-Fen

2003, 24(8):  1427-1429. 

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Azido-3′-deoxythymidine(AZT) was the first clinically approved drug against HIVinfection, despite its undesirable side reactions, such as bone marrow suppression.In our aim to develop new chemical entity of anti-tumor and anti-HIV, the H-phosphonate 6 of AZTconjugate with diosgenin was synthesized by a tandem transesterification reaction for the first time.There are the merits of easy operation and high yield in the reported method.It could be extended to synthesize other diosgenin phosphonate conjugates such as carbohydrate and peptide.

Synthesis and Cleaving Activity of DNA Photocleaver Containing Bromoacetophenone

LI Li-Hua, LIU Dan, TANG Fei-Li, YUAN Gu

2003, 24(8):  1430-1431. 

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Anovel DNA photocleaver containing bromoacetophenone-polyamide was synthesized by DCC coupling reaction in the presence of DMAP, and its DNA cleaving activity was investigated by using pBluescript SK DNA by method of gelelectrophoresis.The result shows that the photocleaver containing bromoacetophenone-polyamide has a remarkable cleaving activity for pBluescript SK DNA.

Synthesis of Cross-linked Poly[styrene(iodosodiacetate)] and Its Application to Azo-arylselenenylation of Alkenes

ZHANG You-Chu, WU Lu-Ling, HUANG Xian

2003, 24(8):  1432-1434. 

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The 2% cross-linked poly[styrene(iodosodiacetate)] reacted with diarylselenides and sodium azides to afford a simple and mild synthetis method of 1-azido-2- arylselenoalkanes.

Studies on the Influences of Magnetic Fields on the Biocatalytic Properties of Schiff Base Complexes for Monooxygenation of Cyclohexane

CHEN Xin-Bin, YANG Yan, HUANG Pei-Zhong, ZHU Shen-Jie

2003, 24(8):  1435-1437. 

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The influences of magnetic fields on the biocatalytic properties of Schiff base mono- and dinuclear complexes for the monooxygenation of cyclohexane by PhIO were studied.It was found that the catalytic activities of these catalysts increase with the increase of the outside magnetic field intensity used, and the effects of magnetic field on the catalytic properties of these dinuclear complexes generally increase with the increase of the number of unpaired d electrons of the metaLIon and the magnetic exchange between the two metals in these dinuclear complexes.Furthermore, it was found that the effect of magnetic field on the iron complex was greater than that on the other metallic complexes, and the effect of magnetic field on the mononuclear complex was greater than that on the dinuclear complex.

Charge-separated State and Electronic Coupling for Photoinduced Electron Transfer Between 9,10-Dicyanoanthracene and Durene

YI Hai-Bo, DUAN Xiao-Hui, LI Xiang-Yuan, YANG Sheng-Yong

2003, 24(8):  1438-1441. 

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In this work, ab initio and DFTcalculations have been performed to investigate the state transitions in photoinduced electron transfer reactions between 9,10-dicyanoanthracene(DCA) and durene(DUR).The face-to-face structure of complex has been optimized by using M＜ller-Plesset method, and the counterpoise method is adopted to consider the basis set superposition error correction of interaction energy.Four low-lying excited singlet states of complex have been investigated by using the method of configuration interaction singles(CIS).It is concluded that the transitions from the S₀state to the S₁and S₂states do not lead to the charge separation.The transition from S₀state to S₃state is found to produce a charge-separated state directly, but the small oscillator strength indicates that the intensity of the charge transfer(CT) absorption is probably quite weak.The decays of charge-separated state to the locally excited states and the ground state have been examined.According to the generalized Mulliken-Hush model, the electronic coupling matrix elements in the charge recombination(CR) processes have been evaluated.Our investigation makes it clear that the direct CT absorption is rather weak, while the CR process from the CTstate to a locally excited state or to the ground state seems possible.

Computation and Simulation of Hydrolysis of ClONO₂on Ice Aerosol

WANG Yu-Wen, LI Quan-Song, CHEN Xue-Bo, FANG Wei-Hai

2003, 24(8):  1442-1446. 

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The MP₂and B₃LYPmethods have been used to study the mechanism of the hydrolysis of chlorine nitrate.The calculation was performed with 6-31G^*and 6-31G^**basis sets.On one hand, one to three water molecules act as a bridge, which makes the hydrolysis of ClONO₂take place easily.On the other hand, the solvent is considered to be uniformly dielectric and its effects were considered by using Onsager model of solvent cage.The relationship between the reactivity and structure for the complexes of ClONO₂with H₂O in neutral water was discussed in details.

Intermolecular Vibrational Frequencies of Complex C₆H₅CH₃...Ar

HU Yi-Hua, WU Huai-Xuan, CHEN Li, LIU Mei-Xi, WANG Xiao-Juan, YANG Shi-He

2003, 24(8):  1447-1450. 

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Acombined experimental and theoretical studies of resonant ionization spectra for van der Waals complexes C₆H₅CH_3...Ar and C₆D₅CD_3...Ar are reported.By using resonant ionization spectrometry, together with time-of-flight mass spectrometry, in supersonic molecular beam, the internal rotation for CH₃and intermolecular vibration for atom Ar in the complexes are exhibited, all observed bands are rationally assigned by isotope effect and calculated at the internal rotational levels and external vibrational levels, and three modes frequencies of van der waals vibrations for complex C₆H₅CH_3...Ar are obtained.

Physicochemical Research on Effect of Pour Point Depressant on Wax Precipitation and Dissolution of Waxy Oil

LI Chuan-Xian, ZHANG Chun-Guang, SUN De-Jun, SUN Jie

2003, 24(8):  1451-1455. 

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The heating cooling procedures were studied with differential scanning calorimeter.Equilibrium wax dissolution temperature(WDT), wax precipitation temperature(WPT) and solubility as well as saturation of undoping and doping pour point depressant were measured and analyzed thermodynamically.The results show that equilibrium WDT is higher than WPT, and pour point depressant(PPD) can make the WDT increase and the WPT decrease, resulting in large depression of pour point of waxy oil.The relationship between wax solubility saturation and temperature accords to Van′t Hoff equation.The dissolving enthalpy and entropy of the wax of pour point depressant doped oiLIncreased, but the precipitation enthalpy and entropy of the wax of pour point depressant doped oil decreased.PPDmakes the critical radius and the potential barrier of nucleation of wax crystaLIncrease, and makes the separation of wax from waxy oil difficult.

Effect of Methanol on Electrochemical Behavior of Microperoxidase

WANG Xiao-Feng, HUANG Xiao-Hua, JIANG Hui-Jun, FENG Yu-Ying, XING Wei, DING Xiao-Lan, LU Tian-Hong

2003, 24(8):  1456-1458. 

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The electrochemical and electrocatalytic properties as well as the structures of MP-11 in the solution without and with 20% methanol were compared by using the electrochemical and Circular dichroism methods.It was found that in the presence of methanoLIn the solution, the reversibility of the electrochemical reaction and electrocatalytic activity of MP-11 for the reduction of H₂O₂increase because in the presence of methanoLIn the solution, the exposure extent of heme in the MP-11 molecule increases, the contents of the α-helix and β-turn structures increase and the content of the random coil structure decreases in the MP-11 molecule.

A Study of TiO₂Photo-catalyst Modified by Air Electrode

HUANG Xing-Jiu, YE Gang, WANG Lian-Chao, LIU Wei, CAI Nai-Cai, LIU Jin-Huai

2003, 24(8):  1459-1463. 

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Anovel composite electrode which has both of the functions of synthesizing H₂O₂and photocatalysis is reported.This double function composite electrode was prepared by loading the photocatalyst TiO₂/Con a novel substrate which can synthesize H₂O₂The porous properties of TiO₂/Cphotocatalysis layer can make the novel carrier synthsizing H₂O₂efficiently.The current efficiency attained a value of 82%(J=15mA/cm²), and the novel carrier made TiO₂gaining an anodic bias which is very important for improving the photocatalytic activity of TiO₂In this novel system, photochemistry and photocatalysis oxidization were combined near the interface of electrode/solution and thus the degradation rate of organic molecules enhanced rapidly.

In-situ IR Spectroscopic Study of Oxidation of NaH₂PO₂on Pt Electrodes in Acidic Solutions

JIANG Tai-Xiang, WU Hui-Huang

2003, 24(8):  1464-1467. 

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The mechanism of electrochemical oxidation of hypophosphite on a polycrystalline platinum electrode was studied by SNIFTIRS (i.e. Subtractively Normalized Interfacial FTIR Spectroscopy) as well as by cyclic voltammetry.The in-situ IR reflectance spectra were analyzed as a function of the Pt electrode potentials in 0.5 mol/L H₂SO₄+0.1 mol/L NaH₂PO₂solution.The in-situ IRband characteristics are those near 2100, 1250 and 1110cm^-1, assigned as the presence of adsorbed hydrogen atom on Pt and non-adsorbed H₃PO₄molecule or phosphate species, respectively.It was concluded that both hydrogen atoms and H₂PO₂are the adsorbed species on Pt in the potential range where the oxidation occurs, and the final oxidation product was H₃PO₄rather than phosphate, different from the oxidation of hypophosphite on Ni electrode.Accordingly, a new mechanism was proposed for the hypophosphite oxidation on Pt electrodes in acidic media, i.e. in the potential range lower than 0.8 V(vs.SCE) the adsorbed H₂PO₂was directly oxidized to phosphate via phosphite, and in the potential range higher than 0.8 V the oxygen-adsorbed species on Pt participates in the oxidation of H₂PO₂into phosphate.

Electrochemical Studies of Reaction Between Dactinomycin and DNA

WANG Su-Fen, PENG Tu-Zhi, LI Jian-Ping

2003, 24(8):  1468-1471. 

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The electrochemical behavior of Dactinomycin(Act-D) and the interaction between Act-Dand DNAwere investigated by using electrochemical method.In 0.1 mol/L NaH₂PO₄-Na₂HPO₄buffer(pH=7.0), Act-Dshowed a pair of oxidative and reductive peaks at -0.19 and -0.51 Vin the cyclic voltammetry.Act-Dreacted with DNAand formed an non-electroactive complex, resulting in a decrease of reductive current.The diffusion coefficient of Act-D(D), binding constant(K) and binding site size(s) of Act-Dand DNAwere obtained simultaneously by nonlinear fitting analysis of electrochemical data based on an electrochemical equation for examining the interaction between irreversible redox compounds and DNA.The results were: Df=2.0×10^-5cm²·s^-1, K=5.87×10⁹cm³·mol^-1, s=8.3. The overall results demonstrate that Act-Dbinds tightly to eight base pairs of ct DNA.The two cyclic penta-depsipeptides of Act-Dreinforce the interaction with DNA.

Spectroscopic Characterization of Glutathione S-Transferase of Asaphis dichotoma

YANG Hai-Ling, GAO Bo, ZENG Qing-Yin, FU Xue-Qi, NIE Li-Jia, ZHU Sheng-Geng, ZHOU Xian-Wan

2003, 24(8):  1472-1476. 

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AnoveLIsoenzyme of glutathione S-transferase(adGST) was purified from the liver intestine of the seashell(Asaphis dichotoma) by GST-Sepharose 4 Baffinity chromatography and reverse HPLC.The enzyme was composed of two subunits with a molecular weight of 23000 for each determined by SDS-PAGE, MALDITOF-MSand gel filtration.The characteristic peak of ultraviolet absorbance spectra of the ad GSTwas at 280 nm, and that of fluorescence excitation spectrum was at 280 nm and that of the fluorescence emission spectrum was at 350 nm.The CDspectra and FTIRspectroscopy show that the ad GSThas a total secondary structure content of about 35% α-helix and 30% sheets.The adGSTwas a kind of global protein.

Studies on the Electrochemical Behavior of Polymer Electrolyte MembraneFuel Cell (PEMFC) by AC Impedance Method

GUO Jian-Wei, MAO Zong-Qiang, XU Jing-Ming

2003, 24(8):  1477-1481. 

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Based on ACimpedance analysis of polymer electrolyte membrane fuel cell(PEMFC) in different states, it is proposed that LR₁can be used to represents its equivalent circuit.The simulation result for LR₁shows that, with the discharge voltage decreasing at various humidification temperatures, inductance Ldecreases whereas system resistance R₁and charge transfer resistance R₂increase.Moreover, it is beneficial to decrease inductance by improving catalyst layer and increasing the amount of drainage.Higher humidification temperature decreases R₁and R₂, though at lower discharge voltage R₂has a large deviance.In a word, the synthesis of LR₁is the internal resistance, which drops at a higher discharge voltage with the humidification temperature arising.The reason for internal resistance decreasing at a lower discharge voltage is that, water prevents both processes of reaction gas from attaining catalyst and the charge transferring, which makes internal cell under capacitance state.The microanalysis agrees with the macro-phenomena, particularly at a higher discharge voltage.

UV-Vis-NIR Reflectance Spectra Characterization of AbsorptanceProperties of Colored Powdery Materials

GUO Hong-You, LI Xiu-Yan, WU Nian-Zu, WANG Ping

2003, 24(8):  1482-1484. 

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UV-Vis-NIRreflectance spectra were used to characterize the absorptivities of colored powdery materials to solar radiation.It was found that the plots of lg(1/R)(Rmeans the reflectance of coating to solar radiation) against Vcolored/V(TiO₂)(volume ratio of the colored powdery materials to TiO₂) were straight lines in the range of Vcolored/V(TiO₂) less than 0.05.From the slopes and intercepts of the straight lines, the absorption coefficients and the maximum depth of penetration can be measured quantitatively.The method can be applied to characterization of the colored powdery materials.

Volumetric Properties of Alanine in Aqueous Glucose and Sucrose Solutions at 298.15K

LI Shu-Qin, SANG Wen-Qiang, LIN Rui-Sen

2003, 24(8):  1485-1488. 

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Densities of L-alanine in aqueous glucose and sucrose solutions were measured at 298.15 Kby an oscillating-tube densimeter.Apparent molar volumes Vφ, limiting partial molar volumes V^0φand number of hydration of alanine Nh were calculated.The transfer volumes from water to sugar-water mixtures were obtained and discussed in terms of the structural hydration interaction model.The results obtained were compared with that in glycerol-water and ethylene glycol-water mixtures.It is concluded that the magnitude of enhancement effect on volume is related to the number of OH groups.

Two Array Manners and Packing Modes in Colloidal Crystals

CONG Hai-Lin, CAO Wei-Xiao

2003, 24(8):  1489-1491. 

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Amonodispersed latex from styrene(St), methyl methacrylate(MMA) and acrylic acid(AA) was synthesized with the soap free emulsion polymerization, and the formation of colloidal crystal by evaporating the water of the latex was investigated.It has been confirmed that there exist two array manners, i.e., hexagonal and square array, and two packing modes, i.e., hexagonal packing and face-centered cubic packing in the forming process of colloidal crystals.The square array originated from the dislocation of the particle in the hexagonal array, the area of it depends on the temperature in the forming process.At a lower temperature such as at 0℃, relatively large areas of square array were observed in the formed colloidal crystal.

Synthesis of Spherical Vaterite CaCO₃Particles by Solid-state Reaction at Room Temperature

REN Yin-Zhe, QI Li-Min, MA Ji-Ming

2003, 24(8):  1492-1494. 

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Submicrometer-sized, spherical vaterite particles were synthesized by solid-state reaction at room temperature in the presence of poly(acrylic acid)(PAA).The obtained products were characterized by XRD, IRand SEM.It was revealed that with increasing PAA amount, the crystal polymorph of CaCO₃particles varied gradually from pure calcite through a mixture of calcite and vaterite to pure vaterite, and the particle size decreased generally.It was proposed that in solid-state reaction, PAAinduced the formation of vaterite and the phase transformation from vaterite to calcite was prevented completely due to the absence of H₂O, resulting in the formation of pure vaterite particles.

A New Facile Synthesis Method of Branched PEG

HE Ming-Lei, SU Zhi-Guo 

2003, 24(8):  1495-1498. 

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The modification of bioactive proteins (peptides, enzymes) by using polyethylene glycol(PEG) has still been a hot filed of research.It has been reported that branched PEG is distinctly superior to linear PEG in the modification of some enzymes.However the existing synthetic methods of branched PEG make it very expensive to be used in research and practice.In this paper, a kind of branched PEG was synthesized via conventional methods used in the synthesis of polypeptide(protection, condensation, and deprotection) using lysine and m PEG5000 as starting materials.In this method, the most important reaction of forming branched PEG was fulfilled in one step by condensation reaction in organic phase.It makes this method remarkably different from other methods.The reaction condition is mild and the yield of the product(61%) is higher.The characterization of products in different steps is consistent with their structures.The ¹HNMR spectrum of our end product branched PEG tallies with its structure.

Studies on the Supported Rare Earth Catalyst of Gas Phase Polymerization of 1,3-Butadiene

ZHANG Yi-Feng, NI Xu-Feng, LI Jun-Fei, LI Wei-Shi, SHEN Zhi-Quan

2003, 24(8):  1499-1502. 

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The supported rare earth catalytic system was synthesized and used in the gas phase polymerization of 1,3-butadiene (Bd) successfully.It is found that the catalyst of silica gel supported Nd(naph)₃-Al(i-Bu)₃-Al(i-Bu)₂Cl has a rather high catalytic activity and high sterospecificity.The catalytic system was found to have an excellent activity when n(Al)/n(Nd)=40-60, n(Cl)/n(Nd)=3-7. Adding a suitable amount of monomer, both Bd and isoprene(Ip) as seed in the preparation of catalyst can greatly increase the catalytic activity of the catalytic system, and Bd is found more effective.The polymerization rate increases rather rapidly and reaches the maximum within 10 min, then decreases slowly.The obtained p(Bd) has a molecule weight about 10⁵-10⁶with cis-1,4 structure above 98% and gel content less than 6%.

Synthesis of Oligomers for PEDEK with Different Endgroups

CAO Jian, DING Hong, NA Hui, LI Xian-Feng, ZHANG Chun-Ling, WU Zhong-Wen

2003, 24(8):  1503-1505. 

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In order to take oligomers as the model compounds to study the microstructure of PEDEK, two linear oligomers with different chain ends were synthesized.Their properties have been investigated by means of MS, ¹HNMR, ICP, IR, DSCand WAXD.The hydroxy-ended oligomer Adue to its intermolecular hydrogen bond has very similar X-ray diffractions to the polymer, while oligomer B′s diffractions are much different from those of the polymer.

Analyses on Electron Beam-Curing Reaction of Epoxy Resin

ZHANG Zuo-Guang, SUI Gang, ZHONG Wei-Hong

2003, 24(8):  1506-1510. 

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The curing process of bisphenol epoxy resin irradiated witHElectron beam (EB) was studied.The effect of different initiators and diluents on radiation reaction was analyzed.IR, ESR, GC-MS were used to study radiation reaction mechanism of epoxy resin by using epoxy propane as a model compound.The cation ring-opening polymerization process including decomposition of diaryliodonium salts under EBradiation and production of protonic acid that initiate polyreaction can be deduced.By analyzing an irradiated area of epoxy resin, it can be seen that intensive scattering of EBoccurs in the resin system.The EB curing reactions spread inwards layer upon layer around active center when epoxy resin system is irradiated and whole cured area consists of many lamellar structures.

Estimation of Kinetic Parameters for Chemical Reactions Based on Monte Carlo Simulation

ZHAN Xiao-Li, LUO Zheng-Hong, CHEN Feng-Qiu, YANG Yong-Rong

2003, 24(8):  1511-1514. 

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Anew method for estimating kinetic parameters of chemical reactions was described.The method combines kinetic experiment data with Monte Carlo simulation result.According to the element reactions, the operating process of Monte Carlo simulation was determined at first, and then the least error between simulative results and experimental results was applied to auto adjust and optimize the kinetic parameters.Therefore, the kinetic parameters were estimated.The new method was applied to estimate kinetic parameters of propylene ammoxidation and the estimative results were analyzed and discussed.The research results show that the new method is feasible and effective without knowing kinetic equations in advance.

Microdomain Structure and Dynamics of Poly(L-alanine)-b-poly (ethylene glycol) Monomethyl Ether Diblock Coploymer Characterized by High Resolution Solid-state NMR

WU Guo-Lin, SUN Ping-Chuan, MA Jian-Biao

2003, 24(8):  1515-1518. 

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The microdomain structure of poly(L-alanine)-b-poly(ethylene glycol)monomethyl ether, MPEG-PLA, used as a new amphiphilic diblock copolymer was characterized by proton spin diffusion experiments with ¹³C detection and ¹ Hwideline separation 2D¹H, ¹³CNMR experiment(WISE-NMRspectroscopy).The MPEG chains could form crystalline as well as amorphous phases, but the degree of crystallinity is considerably lower in the diblock polymer compared with MPEGhomopolymer.And the PLAblocks are very rigid as α-helix and β-sheet forms.The results imply that the region of α-helix forms is quite larger than β-sheet forms.

Studies on the Secondary Structure of Partially HydrolyzedPoly(acrylamide) in the Process of Chemical Oil Recovery

LIAO Guang-Zhi, ZHOU Ji-Sheng, LIU Feng-Qi, MA Ji-Ming

2003, 24(8):  1519-1521. 

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The secondary structure parameters of partially hydrolyzed poly(acrylamide)(HPAM) in the process of chemical oil recovery have been determined by means of GPC-light scattering cooperation.It was found that the mean molecular mass of HPAM had decreased to 4 to 8 times, the molecular mass distribution of HPAM became broad.It has been deduced that the molecular mass decrease of HPAM results from the HPAM degradation and the mechanical degradation is a determinant because the molecular mass distributions of HPAM after degradation were narrower than the results estimated with the random degradation theory.The chain flexibility somewhat decreased when HPAM solution flowed in underground sandstones in the period of 6 to 8 months, that is, (<S²> n/<M>_n)^1/2increased from original 0.065 to 0.075 for HPAM in flooding 2 and 4 years and 0.081 for 6 years, which maybe imply HPMA further hydrolyzed under the underground weak basic condition of the oilfield.

Synthesis and Properties of Crosslinkable Fluorinated Poly(aryl ethers) Terminated with Phenylethynyl Moieties

HU Wei, LIU Bai-Jun, WANG Dong, MA Xiao-Ye, RAO Xian-Hua, LI Ting, JIANG Zhen-Hua, WU Zhong-Wen

2003, 24(8):  1522-1524. 

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The crosslinkable trifluoromethylated poly(aryl ethers) terminated with phenylethynyl moieties(11F-PAE-PEP)s were prepared in two step syntheses.The structure of 11F-PAE-PEP was confirmed by FTIR and ¹HNMR.The crosslinking behavior was studied by DSC.There is a remarkable increase of Tg after crosslinking of the poly(aryl ethers).The Tg values of crosslinked polymers were 437 and 446K, respectively.The crosslinked polymers could not be soluble in common organic solvents, such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidinone, chloroform, and tetrahydrofuran.The temperatures at a 5% mass loss of the crosslinked polymers in air were above 789 K.They showed a good optical property, too.This kind of polymers will be the promising materials used as the microelectronics and optical waveguide devices.

Synthesis of Polybis(2-pyrrolylethoxy)phosphazene and ItsOxidation Crosslinking Reaction and Electroconductivity

LIU Cheng-Mei, CUI Xiao-Jing, WU Chuan-Bao

2003, 24(8):  1525-1527. 

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Akind of reactive inorganic polymer-poly(dichloro)phosphazene was prepared by ring-opening polymerization at a high temperature.Then a new conductive polyphosphazene containing pyrrole groups was synthesized by nucleophilic reaction between the inorganic polymer and sodium salts of N-hydroxyethylpyrrole.The chemical structure and properties of the polymers were characterized by ¹H, ³¹PNMR, FTIR, DSC, TGA and GPC.The experimental results indicate that the molecular weights of pyrrole-containing soluble polymer are Mn=4.1×10⁵, Mw=9.2×10⁵( Mw/ Mn=2.24) and the Tg is 237 K.Ahigh qulity film was obtained from the soluble polymer through spin-coating method.Using FeCl₃as oxidiant, the polymer film underwent crosslinking reaction to form conjugated polypyrrole.After the oxidation reaction, the color of polymer film turned into light black from almost transparent and the conductivity was determined to be 1.7×10^-5S/cm, it is 1×10⁵times greater than that of the original film.The crosslinked polymer shows a high thermal stability.

Influence of Intermolecular Entanglements on CrystallizationBehavior of Macromolecules

FAN Zhong-Yong, YU Ying, WANG Yi-Ren, BU Hai-Shan

2003, 24(8):  1528-1530. 

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Ultra-high molar mass polyethylene(UHPE) or HDPEwas melted at various temperatures or at a constant temperature for various time, and then crystallization from the melt was investigated.The crystallization behavior of UHPE was found to be different from those of HDPE.It was found that the crystallization temperature decreased as the heating time or heating temperature increased.During the melting process, thermal motion of the chains leads to a change of chain conformation from parallel-extended chains to interpenetrated random coils, accompanied by the occurrence of entanglements.As a result, the crystallization temperature shifts to a lower temperature.In addition, the samples of UHPE with less entanglement were prepared by a freeze-drying procedure from dilute solution was proved the effect of entanglements on crystallization behavior of macromolecules.Apreliminary study on the crystallization of the samples indicates that entanglements have a pronounced effect on the crystallization behavior of macromolecules.

Atom Transfer Radical Polymerization of StyreneInitiated by 2-Bromocyclohexanone

WANG Guan-Jun, SHI Yan, FU Zhi-Feng, YANG Wan-Tai

2003, 24(8):  1531-1533. 

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The atom transfer radical polymerization of styrene was carried out with an α-haloketone, 2-bromocyclohexanone, as the initiator in the presence of CuBr/Cu/2,2′-bipyridine or CuBr/ N,N,N′,N″,N″-pentamethyldiethylenetriamine catalytic system.The polymerization proceeded in a living fashion with that the number average molecular weight increased linearly with the increase of monomer conversion and the polydispersity was relatively low through the polymerization process, especially with CuBr/N,N,N′,N″,N″-pentamethyldiethylenetriamine as the catalyst.The initiation efficiency of 2-bromocyclohexanone in both catalysis systems was about 80%. ¹HNMR and ¹³CNMR verified the presence of 2-oxocyclohexyl and bromine atom at the botHEnds of polystyrene chains respectively, which were derived from the 2-bromocyclohexanone.

Separation of Vincoside-lactam from Camptotheca acuminata Fruit with Resins

WANG Rui-Fang, LI Jia-Zheng, SHI Zuo-Qing, SHI Rong-Fu, WANG Zhong, OU Lai-Liang

2003, 24(8):  1534-1536. 

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The content of CPTand VCS-LTcould be improved to 4.88%, 21.52%, respectively from 0.379%, 1.524% in crude extract solution after refined by X-5 resin.Then the refined solution was chromatographically separated with hypercrosslinked resin and the contents of VCS-LTcould be improved to about 60%(CPT15%).The achromaticity needle crystal was obtained after several recrystallization and its structure was confirmed by IR, ¹HNMR, ¹³CNMR, MSand element analysis.