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中文
Table of Content
24 November 2000, Volume 21 Issue 11
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Articles
Preparation and UV Shielding Characteristic of ZnO-coated Ultrafine TiO
2
Particles
ZHAO Xu, YANG Shao-Feng, ZHAO Jing-Zhe, LIU Yan-Hua-XU Hui-Fang, WANG Zi-Chen
2000, 21(11): 1617-1620.
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The synthesis of ZnO coated ultrafine TiO
2
particles by factional homogeneous method is reported in this paper. The diameter of ZnO crystal is 10.2 nm, and the particle diameter of spherical TiO
2
is 40 nm. The influence of the content of ZnO on the coating affection and UV shielding characteristic is investigated. The UV shielding capability of ZnO-coated TiO
2
is higher than that of anatase ultrafine TiO
2
, rutile TiO
2
particles and commercial ZnO.
Enzymatic and Kinetic Properties of Selenium-containing Catalytic Antibody with cGPX Activity
WU Yi-Hui, MA Xue-Yan, DING Lan, LIU Lan-Ying, ZHAO Da-Qing, NI Jia-Zuan,
2000, 21(11): 1621-1626.
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Three selenium-containing catalytic antibodies mHB4, mHB5 and mHB7, which acted as mimics of cytosolic glutathione peroxidase(cGPX), were prepared by chemically introducing selenium into monoclonal antibodies HB4, HB5 and HB7. HB4, HB5 and HB7 were raised against a GSH derivative GSH S DNP dibenzyl ester. The cGPX activity of mHB4, mHB5, mHB7 were 170, 1 867, 32 U/μmol, respectively. The cGPX activity of mHB5 was 0.32 fold of natural rabbit liver cGPX and 1.51 fold of m4A4. About two atoms of selenium existed in each of mHB5 molecule determined by inductively-coupled plasma/mass spectroscopy(ICP-MS). The optimal activity of mHB5 was at between pH 8.4 and 8.8. The reaction catalyzed by mHB5 involved a Ping Pong mechanism. At pH 7.0 and 37 ℃, the apparent second order rate constants for reaction of mHB5 with H
2
O
2
and t ROOH were as followed:
k+1
(H
2
O
2
)=9.71×10
6
L/(mol·min),
k+1
( t ROOH)=5.99×10
5
L/(mol·min). Rate accelerations( k
cat
/ K
m
/ k
uncat
) 9.8×10
6
and 3.7×10
5
fold those of the uncatalytic reaction were observed.
Synthesis and Characterization of Nanocrystalline Materials SrMgTi
1-x
O
3
FU Ju-Xia, QIU Fa-Bin, WU Feng-Qing, GAO Wei, LUO Zhen, XU Bao-Kun, WU Jia-Kun
2000, 21(11): 1627-1630.
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SrMg
x
Ti
1-x
O
3
nanocrystalline materials( x =0.1—0.5) were prepared by the stearic acid gel method. Powder samples were characterized by XRD, TG, DAT, IR, XPS and TEM. The results showed that the grain size d changed with the variations of Mg content x , the temperature of calcination and the time of calcination. The result of XPS showed that the binding energy of O 1
s
spectra changed with the change of Mg
2+
content after the replacement of Mg
2+
for Ti
4+
.
The Solution Structure of Cytochrome b
5
Mutant(E44A/E48A/E56A/D60A)
WU Yi-Bing, LU Jun, QIAN Cheng-Ming, LI Er-Cheng, WANG Jin-Feng, TANG Wen-Xia, ZHU De-Xi, WANG Yun-Hua, WANG Wen-Hu, LU Jun-Xia, XIE Yi, HUANG Zhong-Xian
2000, 21(11): 1631-1632.
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The solution structure of bovine cytochrome b
5
mutant (E44A/E48A/E56A/D60A) has been obtained from
1
H NMR spectra measured at 600 MHz. The final RMSD values with respect to the average structure are (0.056±0.009) nm and (0.105±0.010) nm for backbone and all heavy atoms, respectively. The solution structure, when compared with the X-ray structure of wild type, has no significant changes in the whole folding and secondary structure. Small changes are restricted to local conformation near mutated sites.
Chemical Modification of Single-wall Carbon Nanotube
LI Bo, LIAN Yong-Fu, SHI Zu-Jin, GU Zhen-Nan
2000, 21(11): 1633-1635.
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Single-wall carbon nanotube (SWNT) was prepared by d.c. arc discharge method and purified by filtration method. After refluxed in HNO
3
, the ends of SWNT were opened and oxidized into carboxylate group, which may react with other reagents. For chemical modification of SWNT, the carboxyl terminated SWNT reacted with CH
3
(CH
2
)
15
NH
2
with the aid of the condensation agent DCC to obtain the derivatives of SWNT with the amido-alkyl chain which enhanced the solubility of SWNT in organic solvent. The results of micro IR prove the formation of amido group in SWNT sample(
v
(C—O)=1 647 cm
-1
). The FT Raman results show that SWNT sample preserve its structure after the condensation reaction( ω
r
=181 cm
-1
).
Preparation of Polyoxometalate Nanoparticles with Keggin Structure by Solid-state Reaction at Room Temperature
YOU Wan-Sheng, WANG Yi-Bo, WANG En-Bo, XU Lin, HU Chang-Wen, XIN Xin, Quan, LI Feng
2000, 21(11): 1636-1638.
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The polyoxometalate particles with Keggin structure, (NH
4
)
3
PMo
12
O
40
·9H
2
O(1) and (NH
4
)
3
PW
12
O
40
·7H
2
O(2), were prepared firstly by solid state reaction at room temperature. Their structure, particle sizes and appearances were characterized with elemental analyses, IR, XRD and TEM techniques. The size distribution of nanoparticle 1 is in the range of 5—14 nm, the mean size is 9 nm, and the size distribution of nanoparticle 2 is in the range of 3—12 nm, the mean size is 6 nm. It was found that the product H
2
C
2
O
4
·2H
2
O plays a critical role in preventing the nanoparticles from aggregating to large particles.
Synthesis, Structure and Interlayer Behavior of A New Tantalate KSr
2
Ta
3
O
10
with Perovskite-like Structure
FANG Liang, ZHANG Hui, WU Bo-Lin, YUAN Run-Zhang
2000, 21(11): 1639-1641.
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A new tantalate compound KSr
2
Ta
3
O
10
was synthesized by solid state reaction for the first time in the ternary system K
2
O SrO Ta
2
O
5
, and its single crystals were prepared using flux method. The chemical compositions, crystal structure, optical property, density and melting point of the new compound were characterized by EPMA, XRD, DTA and so on. KSr
2
Ta
3
O
10
crystallizes the orthorhombic system with unit cell parameters a= 0.784 4(1) nm, b =0.777 0(1) nm, c =3.012 7(1) nm and space group P2
1
2
1
2
1
, Z =8. The structure may be described as treble perovskite sheets [KSr
2
Ta
3
O
10
]
-
interleaved with K
+
. Further, it was found that KSr
2
Ta
3
O
10
has intercalation phenomenon. Na
+
, Li
+
, H
+
, NH
4
+
could exchange the interlayer cations K
+
of KSr
2
Ta
3
O
10
, and n hexylamine also could intercalate into the place between the layers of [KSr
2
Ta
3
O
10
]
-
.
Gas Chromatography with Microwave Plasma Torch Atomic Emission Spectrometry Detector for the Determination of Sn, P, Si and B
SHI Yu-Hua, LIU Miao, CAO Yan-Bo, PENG Zeng-Hui, SONG Qing-Yu, WU Li-Hang, YU Ai-Min, JIN Qin-Han
2000, 21(11): 1642-1646.
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The present paper deals with an argon microwave plasma torch atomic emission spectrometry detector(GC-MPT-AED) for gas chromatography, argon was used as the carrier gas, plasma support gas and make up gas. The effect of different kind of gases as the plasma scavenger gas, sheathing gas on the response characteristics for Sn, P, Si and B is discussed. Detection limits, dynamic range and relative standard de
via
tion of the elements Sn, P, Si and B was studied, and the content of element P in Rogor emulsifying oil was also determined.
Determination of Trace Amounts of Rare Earth Elements by ETV-ICP-AES Combined with Microcolumn Separation/Preconcentration
XIONG Hong-Chun, HU Bin, HUANG Wei-Hong, PENG Tian-You, CHEN Shi-Zhong, JIANG Zu-Cheng
2000, 21(11): 1647-1650.
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A sensitive and rapid method for electrothermal vaporization inductively coupled plasma atomic emission spectrometry determination of rare earth elements(Sc, Y, La and Yb) after separation/preconcentration by a micro column packed with immobilized 1-phenyl-3-methyl-4 bonzoyl-5-pyrazone on micro-crystalline naphthalene has been developed. Various influencing factors, such as the acidity of the aqueous solution, flow rate, volume of the sample, dimension of the micro column were investigated in detail. It was found that acetone could be used to dissolve the adsorbed material packed in micro-column. The detection limits for ETV-ICP-AES determinations of Sc, Y, La and Yb with PMBP as a chemical modifier are 14, 32, 190 and 26 pg/mL. The relative standard de
via
tions were 3.1%, 3.5%, 4.8% and 3.4% for Sc, Y, La and Yb, respectively ( n =9, c =10 ng/mL). The Sc, Y, La and Yb contents in a standard reference material of GBW07602(GSV-2) and a real tea sample determined by the proposed method are satisfactory.
Respective Determination of Ascorbic Acid and Dopamine by Controlling Potential Sweeping on the Polyalizarin Red Film Modified Electrode
WAN Qi-Jin, YU Jiu-Hong, WANG Gang, YANG Nian-Jun
2000, 21(11): 1651-1654.
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The preparation of polyalizarin red film modified electrode(PARE) and its electrocatalytic properties to dopamine(DA) and ascorbic acid(AA) were investigated. DA and AA have different voltammetric behaviour on PARE. The electrode reaction of DA on PARE is a quasi reversible process, but the oxidation of AA on PARE is a completely irreversible reaction. The oxidation peak of DA can be separated from that of AA about 200 mV on PARE. Passing through sweep for two times in different potential ranges, DA and AA can be detected in the same system respectively. The reduction peak current of DA is proportional to its concentration in the range of 8×10
-6
—4×10
-3
mol/L and the detect limit can reach 8×10
-7
mol/L. The oxidation peak current of AA is linear with its concentration from 4.0×10
-5
mol/L to 2.0×10
-2
mol/L. Detect limit of it reaches 1.0×10
-5
mol/L. Compared to the direct derivative voltammetry, the analysis results are very satisfactory.
The Study on Recognition of Polydiacetylene Functionalized with Mannopyranoside Mimic Membrance for Escherichia Coli
FAN Yi, LI Ya-Jun, ZHANG Li-Gong, SHI Yu-Lu, JIANG Da-Peng
2000, 21(11): 1655-1657.
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People has known that the recognition between cells and bacteria is related to the glycolipid, as a receptor on the cell surface. Diacetylene moiety in the hydrocarbon region can be cross linked by UV irradiation to form the corresponding polydiacetylene polymer. Color changes of polydiacetylenes have been known to occur in response to a variety of environmental perturbations such as heating, pH, mechanical stress or in the case of biosensor, due to the strong π-π
*
absorption of the conjugation backbone. In this report, polydiacetylene mixed with mannopyranoside monolayer is prepared by Langmuir Blodgett film technology, E.coli K
12
adheres on the monolayer surface after gram strain. The result shows that the mannopyraoside could be recognitized by E.coli, but couldn 't be recognitized by O
111
B
4
and S.flexneri.
The VUV Spectra Properties of (Y,Gd)BO
3
;Eu
WU Xue-Yan, HONG Guang-Yan, ZENG Xiao-Qing, YOU Hong-Peng, Chang-Hong-Kim, Chong-Hong-Pyun, HyunSook-Bal, Byung-Yong-Yu, Il-Eok-Kwon, Cheol-Hee-Park
2000, 21(11): 1658-1660.
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The (Y,Gd)BO
3
;Eu phosphor was synthesized by solid state reaction. The UV spectra showed that in a certain range of Gd
3+
concentration, more Gd
3+
absorbed energy and transferred it to Eu
3+
with its increasing concentration. From the spectra in VUV region, it was observed that both the doping and the concentrations of Gd
3+
, Eu
3+
greatly affected the absorption of the host lattice. The absorbances at 147 nm and 170 nm increased when the Gd
3+
was doped which can be explained as that Gd
3+
transferred energy to BO
4
. The optical properties of (Y,Gd)BO
3
;Eu were the best when the concentration of Eu
3+
was about 0.04.
Comparison of a Low Microwave-powered Thermospray Nebulizer and a Pneumatic Nebulizer for ICP-AES
DING Lan, JIN Hai-Yan, LIU Miao, LIANG Feng, HUAN Yan-Fu, CAO Yan-Bo, ZHANG Han-Qi, JIN Qin-Han
2000, 21(11): 1661-1663.
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The analytical performance of two sample introduction systems, a low-microwave powered thermospray nebulizer and a pneumatic nebulizer, coupled to an inductively coupled plasma atomic emission spectrometer, was compared. Several parameters including the sample uptake rate, the carrier gas flow rate and the observation height(above the load coil) were optimized and compared. Under the optimized conditions, the background equivalent concentration of Mn 257 610 nm, memory effect, HCl concentration effect on emission intensity of some selected elements, detection limits(DLs) and relative standard de
via
tion(RSD) for Cd, Co, Cr, Mn, La with either nebulizer were studied. The DLs obtained with MWTN are lower than those with PN, but the RSDs are worse with MWTN than with PN.
Immobilization of Antigen and Antibody on Gold Surface and Determination Using Fluorescent Method
JIANG Xiong-Ping, XU Dan-Ke, LIU Yao-Qing, MA Li-Ren
2000, 21(11): 1664-1666.
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A Gold surface was modified with N-acetylcysteine to produce a self-assembled monolayer and then a single layer film of rabbit IgG was immmobilized on modified gold surface covalently using carbodiimide hydrochloride(EDC) and N-hydroxysuccinimide(NHS). The competitive method(Ⅰ), the sandwich method(Ⅱ) and the surplus method(Ⅲ) were developed to determine rabbit IgG or goat anti rabbit IgG, respectively. A luminescence analyzer connected with a fluorescence microscope was employed to detect the light intensity of labeled sheep anti rabbit IgG. The results of sensitivity and dynamic range were obtained as 25 mg/L and 25—600 mg/L for method(Ⅰ), 1.0 mg/L and 1—200 mg/L for method(Ⅱ) and 25 mg/L and 25—500 mg/L for method(Ⅲ), respectively.
Studies on the Reaction Between
N
-Phosphoryl Amino Acids and Ribonucleosides
HU Jian-Jun, JU Yong, ZHAO Yu-Fen
2000, 21(11): 1667-1670.
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The interaction between
N
-phosphoryl amino acids and nucleosides in aqueous medium was studied and the products were analyzed on the basis of HPLC and LC-MS-MS techniques. The results demonstrated that peptides and oligonucleotides were simultaneously formed. Different selectivities were observed between the reaction of various kinds of
N
-phosphoryl amino acids and different nucleosides. The results gave some clue for the chemical characteristics of the origin of primordial genetic code.
1
H NMR Studies on Synthetic Isoflavones with p-Substituents on B Ring
LIU Peng, CHEN Rong-Feng, CHANG Jun-Biao, XIE Jing-Xi
2000, 21(11): 1671-1674.
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In this paper,
1
H NMR study on fourteen isoflavones with various p substituents on B ring is reported. The effects of substituents on the chemical shifts of A, B and C ring protons are discussed. Unambiguous assignments of unsubstituted B ring
1
H resonance spectra were made with the aid of superconductive NMR spectroanalysis. There is a linear relationship between the chemical shifts of B ring protons and the substituent parameters. The chemical shifts of 2'(6')-
1
H and 3'(5')-
1
H show a linear correlation with Hammett constants σ
p
and substituent parameter S
0
respectively. The resonance shifts of 3'(5')-
1
H arise from the electron and magnetic anisotropy effects, while the resonance shifts of 2'(6')-
1
H respond to the electron effects of the substituents primarily.
Two New Iridoid Glucosides from Clerodenrum Serratum
WEI Xiao-Mei, ZHU Qi-Xiu, CHEN Jin-Chun, CHENG Dong-Liang
2000, 21(11): 1675-1678.
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Four compounds were obtained from the leaves of Clerodendrum serratum. By means of spectroscopic techniques(such as IR, UV, MS,
1
H NMR ,
13
C NMR and 2D-NMR) and chemical evidences, their structures were elucidated as 7-
O
-
p
-coumaroyloxyugandoside(1), 7-
O
-cinnamoyloxyugandoside(2), acteoside(3) and martynoside(4) respectively. Compounds 1 and 2 were new iridoid glucosides, compunds 3 and 4 were phenylpropanoid glycosides which were obtained for the first time from this plant.
Studies on the Synthesis of 1-Aryloxy(α-substituted)acetyl-3-(substituted)- phenyl-2-diethylamino-2-sulfide(selenide)-1,3,2- diazaphospholidine-4-one and Their Herbicidal Activities
DENG Sheng-Lou, CHEN Ru-Yu, YANG Xiu-Feng
2000, 21(11): 1679-1683.
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In order to look for a new herbicide, a series of novel phosphorus heterocyclic compounds have been prepared by the reaction of P(NEt
2
)
3
with compounds containing 1,2 diamino groups at a high temperature. The structures of compounds Ⅱ were characterized by
1
H NMR and elemental analysis, some of which were characterized by
31
P NMR and MS. The compound Ⅱl was analyzed by X-ray diffraction. The coplanar heterocycle and d
π
-p
π
electronic phenomenon of P_N bond were found. The preliminary biological tests indicated that some of them showed a better selective herbicidal activity.
Studies on the Substituent Effects of New Schiff Base Complexes on the Catalytic Monooxygenation of Cyclohexane
CHEN Xin-Bin, YANG Yan, ZHU Shen-Jie, GUI Ming-De
2000, 21(11): 1679-1687.
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This paper reports the biomimetic catalytic effect of new Schiff base complexes Mn
2
L(L= bis[ N,N'-alkylene 2,2'-(arylmethylene)bis(3, 4-dimethylpyrrole-5-aldimino)]) on the mono-oxygena-tion of cyclohexane with PhIO. The results showed that contrary to electron-donating groups, electron withdrowing groups on the phenyl groups or/and the phenylene groups of the complexes could increase their catalytic activities in the biomimetic catalysis system; with respect to the catalytic monooxygenation, the substituent effects on the phenylene groups of the complexes are greater than those on the phenyl groups; there are linear relationships between the reaction kinetic constant k and the substituent constant σ : lg k = 0.165 8σ-6.090 for the complexes with substituents on the phenyl groups and lg k =0.739 4 [( σ
m
+σ
p
)/2]- 6.478 for the complexes with substituents on the phenylene groups.
Progress in Synthetic Peptide Vaccine
XU Jia-Xi
2000, 21(11): 1688-1693.
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Research progress in synthetic peptide vaccine has been reviewed. Various methods seeking for epitopic peptides, including enzyme hydrolysis and chemical cleavage, deductive method aided by computer, chemically synthetic peptide method and X-ray crystal structure, were discussed. Preparation methods and applications of various synthetic peptide antigens such as peptide-carrier complex antigen, polymeric peptide antigen, etc, used in vaccination recently have been introduced systematically.
The Mannich Reaction of 4-Methylacetophenone with Aromatic Aldehydes and Aromatic Amines
YANG Da-Cheng, ZHANG Guo-Lin, YANG Yu, ZHONG Yu-Guo
2000, 21(11): 1694-1696.
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In the presence of catalytical amount of concentrated hydrochloric acid, 4 methylacetophenone can react directly with benzaldehyde, 4-methylbenzaldehyde and some aromatic amines in ethanol solution at 26~32 ℃ to afford 1-(4-methylphenyl)-3 aryl-3-arylamino-1-propanones with 61%~96% yield. There are seven new compounds among the 17 substances prepared. The IR and
1
H NMR spectra and elemental analyses of these Mannich bases are given and they are consistent with the structures of these compounds.
Studies on γ-Al
2
O
3
Supported Cr Promoted SO
4
2-
/ZrO
2
Solid Superacid Catalysts
LEI Ting, HUA Wei-Ming, TANG Yi, YUE Ying-Hong, GAO Zi
2000, 21(11): 1697-1702.
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The Cr-SZ/Al
2
O
3
series solid superacid catalysts were prepared first by supporting Cr promoted SO
4
2-
/ZrO
2
(SZ) solid superacid catalysts, Cr-SZ, on γ-Al
2
O
3
support. The variation rules of their superacidities, medium strong acidities and weak acidities were investigated by using model reactions. The surface area, sulfur content and zirconia crystallization as well as the catalytic activity of samples for n butane isomerization at low temperature were also studied in detail. It was shown that the both introducing Cr species and supporting Cr-SZ on γ-Al
2
O
3
were beneficial to stabilize the tetragonal ZrO
2
crystal phase that are supposed to be one of the basic conditions of superacidity. Moreover the SO
3
contents of the supported samples were much larger than those of both Cr-SZ and SZ sample. The catalytic activities of some Cr-SZ samples for n butane isomerization were improved greatly after supporting them on γ-Al
2
O
3
. The improvement of both acidity and dehydrogenation ability of samples containing Cr makes contribution to the increasing of their catalytic activities for n butane isomerization. Cr-SZ/Al
2
O
3
sample with proper acidity and dehydrogenation ability shows a high activity for n butane isomerization.
Modeling Enzyme-phage Peptide Recognition——Docking Method Based on Surface Electrostatic Complementary and Solvation Energy
LI Fei, WANG Yu-Hong, LI Wei, ZHOU Hui, MAO You-Gang, SHEN Jia-Cong
2000, 21(11): 1703-1707.
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A novel Docking algorithm is presented which combines a simple electrostatic complementary model with a solvation energy model. A computer program ESCOLD(Electro Static Complementary Optimization for Ligand Docking) has been developed for Docking of phage peptide to a target enzyme. In three test cases where the phage peptides(with six amide residues binding to enzyme) of X-ray crystallographically determined complexes are redocked, the family of the orientations closest to the experimental binding geometry was correctly identified with the solvation energy score.
Theoretical Studies on the C—H Bond Insertion Reaction of Carbenes with Ethers (Ⅲ)——Insertion Reaction of CX
2
(X=H, F, Cl) with Ethyl Methyl Ether
FENG Da-Cheng, LIN Qi-Jun, MA Wan-Yong, WANG Huan-Jie
2000, 21(11): 1708-1712.
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The insertion reactions between CX
2
(X=H, F, Cl) and C—H bonds of ethyl methyl ether have been studied at MP2/6 31G(d) level by using ab initio calculation. The potential barriers for three different C—H bonds(namely α'-C—H bonds in methyl group, α-C—H bonds and β-C—H bonds in ethyl group) are 123.8, 32.5, 157.3 kJ/mol(X=Cl) and 254 3, 130 0, 304 2 kJ/mol(X=F) respectively. No potential barrier is present in the insertion reaction between methylene and C—H bonds adjacent to the oxygen atom and the potential barrier for the insertion between methylene and β-C—H bond in ethyl group is 3.4 kJ/mol. C—H bonds of α-C in ethyl group of ethyl methyl ether are the most favourable to CX
2
insertion, C—H bonds in methyl group come next and β-C—H bongs in ethyl group are the most unfavourable.
The UV-Vis and Fluorescence Spectra of the Amphiphilic Porphyrins Sensitive to the Micellar Microenvironments
MA Chen, ZHANG Yun-Hong, LI Qian-Shu
2000, 21(11): 1713-1716.
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Electronic absorption, fluorescence emission and fluorescence excitation spectra of amphiphilic porphyrins in THF(tetrahydrofuran) solutions and CTAB(cetyltrimethylammonium bromide) micellar solutions are acquired and studied. Tetra(4-hydroxylphenyl)porphyrin (P
0
) and its analogs with one (P
1
), two (P
2
) and three hexadecyl chains (P
3
) exist as the monomers in homogeneous THF, and their similar spectral characteristics indicate that the effects of the substituted hexadecyl groups on the electronic states of porphyrins are negligible in the homogeneous phase of non polar THF solutions. While the absorption spectral characteristics of amphiphilic porphyrins in neutral CTAB micellar solutions are different in the peak positions and FWHH of the Soret bands. P
0
is proposed to be solubilized in the inner core of CTAB micelles, P
1
is probably solubilized near the interface of CTAB micelles. P
2
has a certain aggregating ability, P
3
is the easiest to aggregate according to the FWHH(41.6 nm) of the Soret band. The substituted hexadecyl chains of the amphiphilic porphyrins also affect the pH-dependent fluorescence emission spectra on the relative intensity of Q bands. The fluorescences are quenched at different extents to nearly zero with increasing pH values.
Equilibrium Solubility of Ternary System Cs
2
CO
3
-EtOH-H
2
O at 30 ℃
HU Man-Cheng, LIU Zhi-Hong, GAO Shi-Yang, XIA Shu-Ping, HAO Li-Xia, YUO Xian-Li
2000, 21(11): 1717-1718.
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Solubility of Cs
2
CO
3
-C
2
H
5
OH H
2
O ternary system at 30 ℃ has been studied by using micro equipment for solubility determination. There appear two phases, alcoholic phase and water phase, in the liquid phase. The solubility of Cs
2
CO
3
in water, C
2
H
5
OH and mixed solvent has been determined. The phase diagram indicated that C
2
H
5
OH might be strongly salted out by Cs
2
CO
3
from this system and the equilibrium solid phase is Cs
2
CO
3
·3.5H
2
O.
Studies on Synthesis and Electrochemical Activity of Oxadiazole Derivatives Incorporting Thiophene Ring
ZHANG Zhi-Ming, LI Guo-Wen, MA Yu-Guang, WU Fang, TIAN Wen-Jing, SHEN Jia-Cong
2000, 21(11): 1719-1722.
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A series of novel oxadiazole derivatives containing π-excessive five-memberd ring heterocycle-thiophene(R—OXD) have been prepared as the electron transport layer in organic electroluminescent (OEL) devices. Their molecule structures were characterized by
1
H NMR and elemental analysis. The results of cyclic voltammetry measurements imply that all these R—OXD but F OXD have a higher electron affinity(
E
A
) than 2-(4-biphenyl)-5-(t-butylphenyl) 1,3,4 oxadiazole(PBD) which implies that they are better electron acceptors than PBD. So they are potentially better materials as the electron transfer.
Determination of Response Function by Atom-bond Electronegativity Equalization Method
WANG Chang-Sheng, YANG Zhong-Zhi
2000, 21(11): 1723-1726.
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The response function β(r,r′) is a very important quantity in density functional theory(DFT). With the familiar Berkowitz Parr relation: β(r,r′) =- s(r,r′)+f(r)f(r′)S , it can be proved that the negative internal softness kernels equalize to the response function in the atom bond electronegativity equalization model(ABEEM). In this paper, the Fukui function f a—b of a chemical bond a—b and the response function β(a—b,g) and β(a—b,g—h) that is related with a chemical bond a—b are defined based on DFT and ABEEM, and therefore a new method for determining response function is proposed. With this method, the response function and therefore the softness matrix of the closed system are easily obtained. It is shown from many test examples that the response functions obtained in this way can correctly predict the more active site among the various kinds of chemical bonds.
Stochastic Simulation of CSTR-BZ Reaction System
WEI Qing-Li, WANG Gui-Chang, CAI Zun-Sheng, ZHAO Xue-Zhuang
2000, 21(11): 1727-1732.
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The CSTR-BZ reaction system described by SNB model, in which oscillatory dynamics is varied with flowrate k f, is studied by stochastic analysis. The implication of the minimum reaction concentration is discussed, and the continuous effect of flow rate is also investigated. Comparison with deterministic analysis approach and the results of experiment in CSTR-BZ reaction shows that deterministic description based on mass action law can still be applied effectively.
Studies of SO
2
Poisoning Mechanism for Perovskite LaCoO
3
Model Catalyst
ZHU Yong-Fa, TAN Rui-Qin, FENG Jie, JI Shi-Shan, CAO Li-Li
2000, 21(11): 1733-1737.
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In this work, the SO
2
poisoning mechanism of model catalyst and powder catalyst of LaCoO
3
has been investigated. The changes of the structure and the chemical states of the elements have been characterized using XRD, TEM, AES and XPS. The results showed that the perovskite structure of LaCoO
3
was destroyed by the invading of S. Some La
2
(SO
4
)
3
and CoO species were formed on the surface of the poisoned sample, while La
2
(SO
4
)
3
, La
2
(SO
3
)
3
and CoO species were the main production in the interior of the LaCoO
3
layer, which led to the loss of the catalysis activity. The content of S in the layer increased with the increase of temperature and time. After the sample was poisoned at a relatively high temperature or for a fairly long time, the distribution of S in the LaCoO
3
layer became homogeneous with the depth and the concentration being decreased, suggesting that a dynamic equilibrium was achieved between the poisoning reaction and the decomposition of the sulphurous salts.
Force Titration of ω-Mercapto-n-undecylamine Self-assembled Monolayers by Chemical Force Microscopy
FU Qiang, ZHANG Hua, HE Hui-Xin, LIU Zhong-Fan
2000, 21(11): 1738-1741.
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Chemical force microscopy(CFM) was used to measure the adhesion forces between Au coated Si
3
N
4 tip functionalized with —OH and —NH
2
groups and gold sample functionalized with —NH
2
groups. The curves of the adhesion force as the function of the solution pH values(force titration curve) was obtained. The p
K
1/2
of surface —NH
2
groups estimated from the force titration curve is 8.4 by —OH functionalized tip and 9.0 by —NH
2
functionalized tip.
A Novel Computational Algorithm for Determining the Structure of Protein-phage Peptide Complexes
LI Fei, LI Wei, SHEN Jia-Cong
2000, 21(11): 1742-1744.
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A novel docking algorithm based on the geometric match is proposed for protein-phage peptide complexes. The radii of gyration of protein-phage peptide complexes are used as the criterion of geometric match on the interface, which can be used to screen out the ligand structures with a good geometry fit without any prior description for the contact surface. The energy is evaluated for the structures with a good geometry fit. The algorithm is used to calculate the rigid and flexible docking of four protein phage peptide complexes and predict successfully the native like structures of phage peptides.
Studies of Chiral Discrimination of Diniconazole by Molecular Mechanics
YANG Guo-Sheng, YAN Bo, LEI Lin, WANG Wen-Gang, LIU Cheng-Bu
2000, 21(11): 1745-1747.
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The conformations of the complexes which are formed in the interaction between chiral stationary phase(CSP) and diniconazole enantiomers have been optimized by molecular mechanics. Using molecular mechanics, we calculated the bond lengths, bond angles, dihedral angles and total energies of those complexes respectively. The results show that both R-and S-species of diniconazole can form complexes ( R-CSP and S-CSP) with chiral stationary phase by two hydrogen bonds. The hydrogen bonds of S-CSP are stronger than those of R-CSP. As compared with R-CSP complex, S-CSP complex is more stable, and has a longer retention time than R species in chiral separation. Based on the factor that there are high rotational barriers for the main single bonds in both R-CSP and S-CSP complexes, we can get the same conclusion as in experiments that the separation results have little changes with the temperature. The π-π interaction between R-or S-species of diniconazole and CSP was not found.
Studies on the Active Species of Propylene Oxide Polymerization Initiated by Double Metal Cyanide Complex Catalyst
LIU Xiao-Hua, KANG Mao-Qing, WANG Xin-Kui
2000, 21(11): 1748-1750.
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The effects of organic ethers such as diethyl ether, ethylene glycol diethyl ether and diethyl glycol diethyl ether on the structure of double metal cyanide complex catalyst and the structural changes of such catalyst in the process of propylene oxide polymerization were investigated by EXAFS. The results show that Co in all DMC catalysts is still coordinated by six cyanogens, while Zn is coordinated by O atom in organic complex. The more numerous the number of the ether bond, the higher the coordination numbers of O to Zn ion, the more active the catalyst we make. Five or six O atoms coordinated Zn ion may be the real active center in the process of propylene oxide polymerization.
Studies on Complexation-induced Micellization of Block-graft Copolymer SEPG and PS(OH)
PAN Quan-Ming, LIU Shi-Yong, XIE Jing-Wei, JIANG Ming
2000, 21(11): 1751-1755.
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The complexation in toluene between SEPG, which was prepared by atom transfer radical polymerization(ATRP) with a block-graft architecture, and PS(OH)
via
hydrogen-bonding was investigated by viscometry and laser light scattering(LLS). In the process of complexation the soluble complex-micelles were formed. The viscosity measurements confirm the stable micellization based on hydrogen bonding. The LLS results revealed the dependence of the size and its distribution of the complex-micelles on both hydroyl content in PS(OH) and blend composition.
A Theoretical Model of Supramolecular SLCP Induced by H-bonds
YAN Hua, LI Bo-Geng, LI Bao-Fang, PAN Zu-Ren
2000, 21(11): 1756-1761.
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The supramolecular SLCP induced by H-bonds is an oriented blend. By introduction of the self assembly into Flory Huggins theory, the free energy of mixing and chemical potential of components in isotropic phase were described. The free energy of mixing and chemical potential of components in nematic phase were calculated based on Maier-Saupe theory. The theoretical model on the equilibrium phase diagram of the oriented blend was thus set up. Direction and saturation of hydrogen bonds in self-assembly determine the capability of Host-Guest complex. This is a balance point at which the supramolecule has the highest stability, the Ti is the highest, so there is a peak in the phase diagram. The factors which affect the capability of the Host-Guest complex balance point are the interaction parameter of hydrogen bonds and carboxyl concentration in the copolymer. The stability increases with increase in interaction parameter of H-bond and carboxyl concentration; furthermore, the peak shifts to a low concentration of low mass molecule. There is a critical value for the molecular weight, which affects the stability of mesophase. Over it, Ti is independent on the molecular weight, and the self-assembly is decoupled completely.
Studies on the Tacticity of Poly(methyl methacrylate) Synthesized by Atom Transfer Radical Polymerization
QIAN Jun, GUO Jian-Hua, HAN Zhe-Wen, WU Ping-Ping
2000, 21(11): 1762-1765.
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Two series of PMMA samples have been synthesized by Atom Transfer Radical Polymerization(ATRP) with and without catalytic promoter(aluminum isopropoxide, (i-PrO)
3
Al in the temperature range of 0~100 ℃. Their tacticity has been determined by
13
C Nuclear Magnetic Resonance(NMR). The results showed that the polymers by ATRP were all predominantly syndiotactic, and the tendency to form syndiotactic sequences decreased with the polymerization temperature increase. The tacticity of PMMA was influenced by catalytic promoter, [(i-PrO)
3
Al], because it coordinates with the ester carbonyl group of polymer chain end. The activation parameters governing the tacticity of ATRP were calculated. The results indicate that the same type of active species is present in ATRP and conventional radical system.
Fabrication and Structure Studies of ZnSe;Cu/Polyelectrolytes Multilayer Films
ZHANG Hao, HAO En-Cai, YANG Bai, SHEN Jia-Cong
2000, 21(11): 1766-1770.
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Cu doped ZnSe nanocrystals were synthesized in aqueous solution, the optical properties of which could be controlled accordingly. By the layer-by-layer self-assembly method, the ZnSe;Cu/polyelectrolytes multilayer film was fabricated successfully, which was characterized by UV-Vis absorption spectra, XPS and TEM
et al
.. The surface structure of nanoparticles and the valence of copper could be controlled by the surface modification with reflux, indicated by the increasing of fluorescence efficiency and the XPS results. Moreover, the average size of ZnSe;Cu nanocrystals was found to be~3 nm without obvious aggregation. The films assembled in this way can make brighter luminescence possible.
Synthesis and Characterization of Poly(urethane-imide)s Containing a Disperse Red Type Chromophore in the Side chain
ZHU Na, SUI Yu, YIN Jie, LIU Yan-Gang, ZHU Zi-Kang, WANG Zong-Guang
2000, 21(11): 1771-1775.
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Four novel poly(urethane imide)s(PUIs) containing a diazo nonlinear optical chromophore in the side chain were synthesized by a two step process, which includes preparation of diazo chromophore containing diisocyanates followed by the condensation reaction with dianhydrides. The PUIs obtained were characterized by FTIR spectroscopy, UV-Vis spectroscopy, DSC and TGA. All PUIs exhibit a maximum UV-Vis absorption of the diazo chromophore at the wavelength of about 490 nm. They are soluble in aprotic solvents such as NMP, DMAc, DMF, DMSO and 1,4-butyrolactone. Some are even soluble in common low boiling point solvents such as THF. The high organo solubility of PUIs results from the existence of the flexible urethane moiety in the backbone and a side chain chromophore, which leads to loose chain packing and enlarge free volume. The intrinsic viscosities of PUIs are 0.16~0.31 dL/g. The PUIs possess glass transition temperatures( T
g
) at 171~211 ℃, which are much higher than the corresponding side chain nonlinear optical(NLO) polyurethanes. PUIs based on 4,4′-(hexafluoroisopropylidene) diphthalic anhydride(6FDA) and tolulene 2,4-diisocyanate(TDI) possess higher T
g
than those based on 3,3′ , 4,4′-diphenylether-tetracarboxylic acid dianhydride(OPDA) and methylenediphenylene diisocyanate(MDI). Two steps of weight loss are found in TGA curves of PUIs. The initial decomposition temperatures of PUIs are around 300 ℃, which is attributed to the thermal decomposition of the urethane moiety and the side chain chromophore.
Preparation and Characterization of Temperature-sensitive Poly(N-isopropylacrylamide)/Poly(vinyl alcohlo) Hydrogels
ZHANG Xian-Zheng, ZHUO Ren-Xi
2000, 21(11): 1776-1778.
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Poly(
N
-isopropylacrylamide)/poly(vinyl alcohol)(PNV) hydrogels were prepared by repetitive freezing and thawing. This kind of hydrogels was formed through physical crosslinking,
i.e.
hydrogen bonds during the freezing process. The swelling ratio and deswelling/reswelling kinetics were measured gravimetrically and this novel hydrogel exhibits a temperature-sensitivity. This hydrogel may be useful both in biomedical and biotechnological fields.
Decomposition Kinetic Model of Peroxide-mixtured Initiator and Its Application
SHAN Guo-Rong, WENG Zhi-Xue, HUANG Zhi-Ming, PAN Zu-Ren
2000, 21(11): 1779-1781.
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After studying the measurement method of peroxide concentration by iodometry, the decomposition kinetics of five types of peroxides were investigated in detail. On the basis of the additive property for rate, a decomposition kinetic model of peroxide-mixtured initiator has been deduced. The model values of decomposition rate constant coincided with the experimental data. The kinetic behavior of the vinyl chloride suspension polymerization with peroxide mixture as initiators can be predicated by using the model of decomposition rate constant of peroxide mixture and simulating the model of vinyl chloride polymerization.
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