2010 Volume 21 Issue 10

Synthesis and in vitro antibacterial activities of 7-(3-aminopyrrolo[3,4-c]pyrazol-5(2H,4H,6H)-yl) quinolone derivatives
Xin Guo , Yi Liang Li , Yu Fei Liu , Hui Yuan Guo , Yu Cheng Wang
2010, 21(10): 1141-1144  doi: 10.1016/j.cclet.2010.06.011
[Abstract](62) [FullText HTML] [PDF 251KB](0)
Abstract:
A series of novel 7-(3-aminopyrrolo[3, 4-c]pyrazol-5(2H, 4H, 6H)-yl)quinolone derivatives were designed, synthesized and evaluated for in vitro antibacterial activities. Compounds 6g, 7g and 7h with the potencies similar to those of gemifloxacin, moxifloxacin, gatifloxacin and levofloxacin against Gram-positive organisms, worth further investigation.
Synthesis and biological evaluation of some novel-3-(5-substituted benzimidazol-2-yl)-5-arylisoxazolines
Vanga Malla Reddy , Kunduru Ravinder Reddy
2010, 21(10): 1145-1148  doi: 10.1016/j.cclet.2010.06.017
[Abstract](60) [FullText HTML] [PDF 231KB](0)
Abstract:
The synthesis of a new series of 3-(5-substituted benzimidazol-2-yl)-5-arylisoxazolines (6a-h) was achieved in excellent yields by the condensation of 1-(1H-benzimidazol-2-yl)-3-(substituted phenyl)prop-2-en-1-ones (5a-h) with hydroxylamine at room temperature. These 1-(1H-benzimidazol-2-yl)-3-(substituted phenyl)prop-2-en-1-ones (5a-h) were obtained by the condensation of 2-acetyl benzimidazoles (4a-d) with different aromatic aldehydes, which in turn were obtained by the oxidation of 2-(α-hydroxy)ethyl benzimidazoles (3a-d) prepared by the reaction of o-phenylenediamines (1a-d) with α-hydroxy propionic acid 2. The synthesized compounds were characterized by their IR, 1H NMR and MS analyses. These compounds were screened for their antibacterial and antifungal activity by standard methods and found some of them active.
A novel series of 2,5-disubstituted 1,3,4-thiadiazoles as potential anticonvulsant agent
Harish Rajak , Chinmay K. Behera , Rajesh S. Pawar , Pradeep K. Singour , Murli Dhar Kharya
2010, 21(10): 1149-1152  doi: 10.1016/j.cclet.2010.04.012
[Abstract](62) [FullText HTML] [PDF 246KB](0)
Abstract:
In pursuit for better antiepileptic drug and the importance of semicarbazones and 2, 5-disubstituted 1, 3, 4-thiadiazoles as anticonvulsant pharmacophore, a series of novel N-({5-[(6-methyl-1-benzofuran-3-yl) methyl]-1, 3, 4-thiadiazol-2-yl}carba-mothioyl)-2/3/4-substitutedbenzamide were designed, synthesized and evaluated for their anticonvulsant activity. The findings of the present studies confirmed that the pharmacophore model with four binding sites is crucial for anticonvuisant activity. Structure-activity relationships among synthesized compounds were also established.
Design and synthesis of novel cytotoxic podophyllotoxin derivatives
Wen Li Xi , Qian Cai , Yan Bo Tang , Hua Sun , Zhi Yan Xiao
2010, 21(10): 1153-1156  doi: 10.1016/j.cclet.2010.03.040
[Abstract](71) [FullText HTML] [PDF 269KB](0)
Abstract:
In order to investigate the effect of different C4 linkage moieties on the cytotoxicity of podophyllotoxin derivatives, novel 4-N-and 4-C-substituted 4'-O-demethylepipodophyllotoxin derivatives were designed and synthesized. All the compounds were tested against A549 and MCF-7 tumor cells in vitro, and six compounds showed significant cytotoxicity. The most active compound 9f was superior to GL-331, and exhibited potent cytotoxicity with IC50 value at 10-7 mol/L level.
An improved synthesis of bis (cyclopentadienone)
Ming Ming Yu , Xia Li , Miao Luan , Jun Na Gao , Qiu Zhi Shi , Ming Sheng Tang , Liu He Wei
2010, 21(10): 1157-1161  doi: 10.1016/j.cclet.2010.04.005
[Abstract](56) [FullText HTML] [PDF 307KB](0)
Abstract:
An improved strategy for the synthesis of 3, 3'-(oxy-p-phenylene) bis (2, 4, 5-tdphenylcyclopentadienone) was developed, which includes three steps:Friedel-Crafts reaction, oxidation and condensation. Importantly, the use of KMnO4 made the second step simple and efficient, which has potential application to synthesis of bis (cyclopentadienone)s. The course of oxidation has been confirmed by isolated intermediates.
A green and efficient oxidation of benzylic alcohols using H2O2 catalyzed by Montmorillonite-K10 supported MnCl2
Gholam Reza Najafi
2010, 21(10): 1162-1164  doi: 10.1016/j.cclet.2010.05.031
[Abstract](57) [FullText HTML] [PDF 389KB](0)
Abstract:
Primary and secondary benzylic alcohols were oxidized to the corresponding carbonyl compounds in good to high yields by environmentally friendly and green oxidant, H2O2 catalyzed by Montmorillonite-K10 supported manganese(Ⅱ) chloride.
First total synthesis of ocimarin
Jin Hui Yang , Yun Feng Li , Cong Bin Ji , Shi Zhi Jiang , Wan Yi Liu
2010, 21(10): 1165-1166  doi: 10.1016/j.cclet.2010.04.038
[Abstract](67) [FullText HTML] [PDF 205KB](1)
Abstract:
A facile approach for the first synthesis of ocimarin, naturally occurring coumarins, was developed by employing a cerium (Ⅲ) chloride heptahydrate-catalyzed Pechmann condensation of phenols and β-keto esters in a solvent-free system as key step, by which ocimarin was achieved by three steps starting from acetylacetic ether and resorcinol with total yield 23.2%. All structures of new compounds were confirmed by IR, 1H NMR and MS.
Strontium chloride-catalyzed one-pot synthesis of 4(3H)-quinazolinones under solvent-free conditions
Min Wang , Zhi Guo Song , Ting Ting Zhang
2010, 21(10): 1167-1170  doi: 10.1016/j.cclet.2010.05.021
[Abstract](57) [FullText HTML] [PDF 206KB](0)
Abstract:
Strontium chloride was used as an efficient and recyclable catalyst in one-pot condensation of anthranilic acid, ortho esters and amines leading to the formation of 4(3H)-quinazolinone derivatives in good yields at room temperature under solvent-free conditions.
An efficient and mild protocol for the synthesis of unsymmetrical ureas in the absence of catalyst and additives
Rahman Hosseinzadeh , Yaghoub Sarrafi , Nora Aghili
2010, 21(10): 1171-1174  doi: 10.1016/j.cclet.2010.06.014
[Abstract](49) [FullText HTML] [PDF 213KB](0)
Abstract:
A new practical method for the synthesis of unsymmetrical ureas was achieved by reaction of phenylurea with primary and secondary amines under neutral and mild condition in very good yields. The reaction took place in refluxing dioxane and does not require any catalyst or additives.
Greener approach towards the facile synthesis of 1,4-dihydropyrano[2,3-c]pyrazol-5-yl cyanide derivatives at room temperature
Ravi S. Balaskar , Sandip N. Gavade , Madhav S. Mane , Bapurao B. Shingate , Murlidhar S. Shingare , Dhananjay V. Mane
2010, 21(10): 1175-1179  doi: 10.1016/j.cclet.2010.06.013
[Abstract](57) [FullText HTML] [PDF 226KB](0)
Abstract:
This report describes triethylammonium acetate (TEAA) ionic liquid catalyzed one pot synthesis of 6-amino-4-aryl-5-cyano-3-methyl-1-phenyl-1, 4-dihydropyrano[2, 3-c]pyrazoles by the reaction of aromatic aldehyde, malononitrile and 3-methyl-1-phenyl-2-pyrazolin-5-one at room temperature. TEAA plays dual role as reaction media and catalyst. It can also be easily recovered and reused in several runs. TEAA provides greener reaction protocol to present methodology which obviates the need of organic solvents, expensive and toxic catalyst.
Clean synthesis of 1,8-dioxooctahydroxanthenes promoted by DABCO-bromine in aqueous media
Mohammadali Bigdeli
2010, 21(10): 1180-1182  doi: 10.1016/j.cclet.2010.05.018
[Abstract](47) [FullText HTML] [PDF 194KB](0)
Abstract:
An efficient procedure is reported for the synthesis of 3, 3, 6, 6-tetramethyl-9-aryl-1, 8-dioxooctahydroxanthenes using a one-pot condensation of arylaldehydes and 5, 5-dimethyl-1, 3-cyclohexandione in the presence of DABCO-bromine (TDB) as an acid catalyst. To the best of our knowledge this is the first time that DABCO-bromine is used as an acid catalyst in aqueous media for this type of reaction. This method provides several advantages such as use of water as solvent, easy and clean synthesis, simple work up and versatility.
One-pot synthesis of tri-and tetra-substituted imidazoles using sodium dihydrogen phosphate under solvent-free conditions
Zahed Karimi-Jaberi , Mohammad Barekat
2010, 21(10): 1183-1186  doi: 10.1016/j.cclet.2010.06.012
[Abstract](49) [FullText HTML] [PDF 209KB](0)
Abstract:
Sodium dihydrogen phosphate (NaH2PO4) efficiently catalyzes the condensation reaction of benzil, aldehydes, amines and ammonium acetate in a four-component reaction under solvent-free conditions. The reaction proceeds rapidly and affords the corresponding tetra-substituted imidazoles in high yields. Also an efficient route was developed for the synthesis of tri-substituted imidazoles from condensation of benzil, aldehydes and ammonium acetate using NaH2PO4.
A mild and efficient method for the methoxymethylation and acetylation of alcohols promoted by benzyltriphenylphosphonium tribromide
Farhad Shirini , Gholam Hossein Imanzadeh , Seyyed Ali Reza Mousazadeh , Iraj Mohammadpoor-Baltork , Masoumeh Abedin
2010, 21(10): 1187-1190  doi: 10.1016/j.cclet.2010.04.031
[Abstract](58) [FullText HTML] [PDF 493KB](0)
Abstract:
A mild and efficient method for the conversion of alcohols to their corresponding methoxymethyl ethers and acetates using benzyltriphenylphosphonium tribromide (BTPTB) as catalyst is described. All reactions were performed under completely heterogeneous reaction conditions in good to high yields.
An efficient and green preparation of 5-aminophosphonate substituted pyrimidine nucleosides under solvent-free conditions
Xin Ying Zhang , Ying Ying Qu , Xue Sen Fan
2010, 21(10): 1191-1194  doi: 10.1016/j.cclet.2010.04.037
[Abstract](49) [FullText HTML] [PDF 226KB](0)
Abstract:
An environmentally benign and highly efficient one-pot preparation of α-aminophosphonates under solvent-free conditions was developed. By employing this method, 5-aminophosphonate substituted pyrimidine nucleosides were synthesized in good to excellent yields starting from 5-formyl-2'-deoxyuridine, aniline and dimethylphosphite.
Excited state intramolecular proton transfer of novel conjugated derivatives containing hydroxy and imino groups
Xiao Lin Zhong , Fang Gao , Qi Wang , Hong Ru Li , Sheng Tao Zhang
2010, 21(10): 1195-1198  doi: 10.1016/j.cclet.2010.05.032
[Abstract](49) [FullText HTML] [PDF 332KB](0)
Abstract:
This letter presents excited state intramolecular proton transfer (ESIPT) of new conjugated derivatives containing hydroxy and imino groups. ESIPT occurrence in one photon process is confirmed by well-separated emission band for the derivatives. Twophoton absorption (TPA) induced ESIPT emission has been determined by Ti:sapphire femtosecond laser tuning from 700 nm to 800 nm at the internals of 20 nm.
Synthesis and photochromic behavior of mono-,and biphotochromic system linked by p-phenylene bridge
N. O. Mahmoodi , K. Tabatabaeian , A. Ghavidast
2010, 21(10): 1199-1202  doi: 10.1016/j.cclet.2010.04.036
[Abstract](44) [FullText HTML] [PDF 334KB](0)
Abstract:
The synthesis of mono-and bis-1, 3-diazabicyclo[3.1. 0]hex-3-ene derivatives with indole ring and p-phenylene spacer, which behave as photochromic materials, is reported. The structure-photochromic behavior relationship (SPBR) of the synthesized compounds has been analyzed.
Chromones from an ascomycete,Chaetomium aureus
Li Mei Li , Qiang Zou , Guo You Li
2010, 21(10): 1203-1205  doi: 10.1016/j.cclet.2010.05.023
[Abstract](69) [FullText HTML] [PDF 241KB](2)
Abstract:
A novel chromone, named chaetoaurin (1), along with six known chromone derivatives (2-7), was isolated from the ethyl acetate extract of a solid-state fermented culture of Chaetomium aureus. Their structures were elucidated by extensive spectral analysis. All of these compounds were reported from C. aureus for the first time.
Separation of gibberellin A4 from A4 and A7 mixture by selective complex
Lai Wen Hu , Yong Yao Zhang , Yun Guo , Cong Wang , Zhi Min Jin
2010, 21(10): 1206-1208  doi: 10.1016/j.cclet.2010.05.034
[Abstract](57) [FullText HTML] [PDF 367KB](0)
Abstract:
Gibberellin A4 is effectively separated from mixture of gibberellin A4 and its analogue gibberellin A7, in the form of its crystalline complex with N, N, N', N'-tetramethylethylenediamine. After removing the tetramethylethylenediamine from the crystal by dilute HCl, gibberellin A4 is obtained a purity of 98.1% and a yield of 72.7%.
Two new steroidal alkaloids from Veratrum nigrum var.ussuriense
Xue Feng Zhou , Zhi Gang Gao , Xu Ran Han , Wei Jie Zhao , Shi Sheng Wang
2010, 21(10): 1209-1212  doi: 10.1016/j.cclet.2010.06.016
[Abstract](55) [FullText HTML] [PDF 209KB](0)
Abstract:
Two new steroidal alkaloids, veraussines A(1) and B(2) were isolated from the roots and rhizomes of Veratrum nigrum var. ussuriense. Their structures were determined as N-(ethoxycarbonyl)-1α, 2β, 3α, 15α-tetrahydroxy-5β-jervanin-12-en-11-one (1) and N-(methoxycarbonyl)-1α, 2β, 3α, 15α-tetrahydroxy-5β-jervanin-12-en-11-one(2)by spectroscopic analysis.
Laurenidificin,a new brominated C15-acetogenin from the marine red alga Laurencia nidifica
Xu Liu , Xiao Ming Li , Chun Shun Li , Nai Yun Ji , Bin Gui Wang
2010, 21(10): 1213-1215  doi: 10.1016/j.cclet.2010.06.015
[Abstract](47) [FullText HTML] [PDF 226KB](0)
Abstract:
A new brominated C15-acetogenin, namely, laurenidificin, was isolated from the marine red alga Laurencia nidifica. Its structure was determined on the basis of spectroscopic methods.
A new triterpene saponin from Panax japonicus C.A.Meyer var major (Burk.) C.Y.Wu et K.M.Feng
Hong Zhao , Lin Shi , Jia Qing Cao , Wei Li , Xia Wen , Yu Qing Zhao
2010, 21(10): 1216-1218  doi: 10.1016/j.cclet.2010.06.010
[Abstract](47) [FullText HTML] [PDF 211KB](0)
Abstract:
One new triterpene saponin was isolated from Panax japonicus C. A. Meyer var major(Burk.)C. Y. Wu et K. M. Feng, and established as oleanolic acid 3-O-[β-D-glucopyranosyl-(1→2)-β-D-glucuronopyranosyl-6'-O-n-butyl ester]which showed moderate antitumor activities against the A2780 cells and OVCAR-3 cells. Its structure was established by means of spectral data, particularly NMR, including HSQC and HMBC techniques.
Direct determination of trace amounts of acetic acid using a novel ambient glow discharge ion source
Xiao Hao Wang , Kun Liu , Fei Tang , Jiu Ming He , Xue Ye Wei , Zeper Abliz
2010, 21(10): 1219-1222  doi: 10.1016/j.cclet.2010.05.008
[Abstract](51) [FullText HTML] [PDF 1423KB](0)
Abstract:
A novel ambient glow discharge ion source with improved line-cylinder electrodes is put forward and designed in this paper. The diameters of inner and outer electrodes are 0.16 and 4 mm respectively. With a special assembly method, a perfect coaxiality of the two electrodes is obtained. From the gas discharge experiment, it can be seen that the discharge can stably work in normal glow discharge mode. The operating currents of the ion source are in an order of milliamperes and can generate a much larger number and wider variety of reagent ions. The MS experiment shows that the ion source has higher detection sensitivity.
Simultaneous determination of metronidazole and tinidazole in plasma by using HPLC-DAD coupled with second-order calibration
Li Qun Ouyang , Hai Long Wu , Ya Juan Liu , Jian Yue Wang , Yong Jie Yu , Hong Yan Zou , Ru Qin Yu
2010, 21(10): 1223-1226  doi: 10.1016/j.cclet.2010.04.016
[Abstract](55) [FullText HTML] [PDF 339KB](0)
Abstract:
A method using HPLC-DAD coupled with second-order calibration was developed to simultaneously determine metronidazole and tinidazole in plasma samples in this paper. The second-order calibration method based on APTLD (alternating penalty trilinear decomposition) algorithm was proposed to analyze the three-way HPLC-DAD data from both standard and prediction samples, which makes it possible that calibration can be performed even in the presence of unknown interferences with a simple and green chromatographic condition and short analysis time. The results showed that good recoveries were obtained although the chromatographic and spectral profiles of the analytes of interest as well as background were partially overlapped with each other in plasma samples.
Characterization of gold nanoparticle bioconjugation by resonance light scattering correlation spectroscopy
Xin Qiu , Li Chuan Tang , Chao Qing Dong , Ji Cun Ren
2010, 21(10): 1227-1230  doi: 10.1016/j.cclet.2010.05.007
[Abstract](43) [FullText HTML] [PDF 1443KB](0)
Abstract:
Gold nanoparticles (GNPs) have been widely used as probes and nanomaterials in certain biological and biomedical fields thanks to its special physical and chemical properties. However, it is still difficult to characterize GNPs-bioconjugates in solution, which has greatly limited further bioapplications of GNPs. In this study, we reported a single particle method for characterizing GNPsbiomolecules in solution using resonance light scattering correlation spectroscopy (RLSCS). The interaction of GNPs with bovine serum albumin (BSA) and thiol-modified oligonucletides were investigated.
Simultaneous determination of flavonoids and anthraquinones in chrysanthemum by capillary electrophoresis with amperometry detection
Yin Yan Zhang , Zi Cheng Li , Jin Kun Zhu , Zhi Yong Yang , Qing Jiang Wang , Pin Gang He , Yu Zhi Fang
2010, 21(10): 1231-1234  doi: 10.1016/j.cclet.2010.04.040
[Abstract](56) [FullText HTML] [PDF 259KB](0)
Abstract:
A high-performance capillary electrophoresis with amperometry detection method (CE-AD) has been developed for the analysis of flavonoids and anthraquinones (emodin, kaempferol, apigenin, luteolin and rhein) in chrysanthemum. Under optimum conditions, these five analytes were base-line separated within 17 min using a borate-phosphate running buffer (1.5×10-2mol/L borate-3×10-2 mol/L phosphate running buffer, pH 9.0) at a working potential of +0.90 V (vs. SCE) and a separation voltage of 19 kV. The linear relationship between concentration and current response was obtained with detection limits (S/N=3) ranging from 1.0×10-7 to 2.1×10-7 g/mL for all analytes. This proposed method was successfully used in the analysis of four kinds of chrysanthemum with relatively simple extraction procedures, the assay results were satisfactory.
Tetracycline selective electrode based on molecularly imprinted polymer particles
Zhi Yong Guo , Pan Pan Gai , Jing Duan , Hui Na Zhang , Sui Wang
2010, 21(10): 1235-1238  doi: 10.1016/j.cclet.2010.04.007
[Abstract](47) [FullText HTML] [PDF 562KB](0)
Abstract:
Tetracycline selective electrode using molecularly imprinted polymer particles as quasi-ionophore was constructed the first time, and its performance was carefully characterized. Due to the specific recognition of tetracycline by the particles, the selectivity coefficients for routine interferences were less than 10-4. Benefited from the absence of tetracycline in the sensitive membrane and the optimized composition of the inner filling solution, the limit of detection of the electrode was reduced to about 2.5×10-8 mol/L. It exhibited a good electrode slope 57.6 mV/decade near the theoretical Nernstian one, with a wide linear working range from 6.0×10-8 to 1.0×10-3 mol/L. The fabricated electrode should be used in pH 2-4, response time of which was less than 200 s when the concentration of tetracycline was higher than 1.0×10-6 mol/L and no more than 30 min at the concentration of 1.0×10-8 mol/L.
Attachment of tyrosinase on mixed self-assembled monolayers for the construction of electrochemical biosensor
Xue Ping Ji , Xian Rui Li , Na Wang , Rui Xing Ni , Xiao Hong Liu , Hua Ai Xiong
2010, 21(10): 1239-1242  doi: 10.1016/j.cclet.2010.05.022
[Abstract](44) [FullText HTML] [PDF 308KB](0)
Abstract:
A mixed self-assembled monolayers (SAMs) of thioctic acid (T-COOH) and thioctic acid amide (T-NH2) were used to immobilize tyrosinase for fabricating biosensor. The results showed that the mixed SAMs prepared from solution at the ratio of 1:4provided an excellent microenvironment for enzymatic reaction between tyrosinase and substrate. The biosensor exhibited a fast response and high sensitivity for sensing substrate.
A novel sensor of potassium ions based on mode-filtered light detection
Xiao Hong Zhao , Li Ping Yang , Suo Zhu Wu , Wen Ping Cheng , Shao Min Shuang , Chuan Dong
2010, 21(10): 1243-1246  doi: 10.1016/j.cclet.2010.05.020
[Abstract](33) [FullText HTML] [PDF 257KB](0)
Abstract:
A novel potassium ions sensor based on mode-filtered light detection was reported. The analyzer was consisting of an optical fiber immobilized with a dye of bromocresol green and a fused-silica capillary. It was found that mode-filtered light intensity decreased with the concentration of potassium ions and a linear detection range of 0.25-20 mmol/L(R2=0.9977) was obtained with a detection limit of 9×10-5 mol/L as well as fast response, good reproducibility and reversibility in the working concentration range.
A new fluorinated poly (ether amide) bearing xanthene group
Ting Li , Shou Ri Sheng , Mei Hong Wei , Cheng Chen , Cai Sheng Song
2010, 21(10): 1247-1250  doi: 10.1016/j.cclet.2010.04.017
[Abstract](50) [FullText HTML] [PDF 232KB](0)
Abstract:
A new fluorinated poly (ether amide) bearing xanthene group was prepared from 9, 9-bis[4-(2-trifluoromethyl-4-aminophenox-y) phenyl]xanthene (BTFAPX) with 9, 9-bis[4-(4-carboxyphenoxy) phenyllxanthene(BCAPX)in the presence of triphenyl phos-phate and pyridine (Py). The polymer had the weight-average molecular weight (Mw) of 69, 000 and number-average molecular weight (Mn) of 39, 000, showed the glass transition temperature (Tg) of 267℃, 5% weight loss temperature(Td5)over 460℃ both in N2 and air, and char yield of 62% at 800℃ in N2. This polymer was amorphous and readily soluble in amide-type solvents such as N, N-dimethylacetamide (DMAc), and even in m-cressol, Py and tetrahydrofuran (THF) at room temperature, and exhibited tensile strength of 74 MPa, elongation at break of 6%, tensile moduli of 2.2 GPa. The polymer had low dielectric constant of 3.69 (100 Hz), low moisture absorption of 0.56%, and high transparency with an ultraviolet-visible absorption cut-off wavelength at 334 nm.
Triple-transforming gel prepared by β-cyclodextrin,diphenylamine and lithium chloride in N,N-dimethylacetamide
Yuan Yuan Li , Wen Jing Zhao , Hua Cheng Zhang , Tao Sun , Wei An , Fei Fei Xin , Ai You Hao
2010, 21(10): 1251-1254  doi: 10.1016/j.cclet.2010.04.018
[Abstract](53) [FullText HTML] [PDF 1192KB](0)
Abstract:
This paper describes a triple-transforming gel system(gel-sol-gel')for the first time, which is a thermo-responsive and multicomponent organogel prepared by β-cyclodextrin (β-CD), diphenylamine(DPA)and lithium chloride (LiCl) in N, N-dimethylacetamide (DMAC) in a suitable proportion based on the supramolecular interactions. In the triple-transforming gel system, a gel (gel A) could be formed by β-CD, DPA and LiCl in DMAC at room temperature based on stirring, then the gel could transform into a clear solution based on heating, and then the other gel (gel B) can be formed at a relatively high temperature(Tgel, the gelation temperature by heating). The two gel states in the triple-transforming gel system have different microstructures. This gel system was characterized by OM, SEM, IR and rheology.
Synthesis and characterization of biodegradable amphiphilic PEG-grafted poly (DTC-co-CL)
Qiu Jin Zhang , Wei Pu Zhu , Zhi Quan Shen
2010, 21(10): 1255-1258  doi: 10.1016/j.cclet.2010.04.032
[Abstract](58) [FullText HTML] [PDF 284KB](0)
Abstract:
A novel biodegradable copolymer, poly (5, 5-dibromomethyltrimethylene carbonate-co-ε-caprolactone)(poly(DBTC-co-CL)) with pendant bromine groups, was synthesized via ring-opening polymerization(ROP)of ε-caprolactone(CL)and 5, 5-dibromomethyltrimethylene carbonate (DBTC) using stannous octoate (Sn(Oct)2) as catalyst. Then the pendant bromine groups were completely converted into azide form, which permitted "click" reaction with alkyne-terminated polyethylene (A-PEG) by Huisgen 1, 3-dipolar cycloadditions preparing biodegradable amphiphilic poly (DTC-co-CL)-g-PEG graft copolymer. The graft copolymer was characterized by nuclear magnetic resonance(NMR)and size-exclusion chromatography (SEC).
Preparation of sulphonate-containing core/shell latex particles via seeded emulsion copolymerization
Ji Shuai Wang , Wei Deng , Yun Shen Chen , Cheng You Kan
2010, 21(10): 1259-1262  doi: 10.1016/j.cclet.2010.04.019
[Abstract](51) [FullText HTML] [PDF 828KB](0)
Abstract:
In this study, P(St-MAA)seed latex particles were first prepared via soap-free emulsion polymerization of styrene(St)and methacrylic acid (MAA), then the seed particles were allowed to swell with St at room temperature, and the P(St-MAA)/P(St-NaSS) core/shell latex particles were then synthesized via seeded emulsion copolymerization of St and sodium styrene sulphonate (NaSS) using AIBN as initiator in the presence of N, N'-methylenebisacrylamide (BAA, water-soluble crosslinker). Results showed that the polymerization could be carried out smoothly when the ratio of BAA to total monomers was less than 3 mol%, the narrow dispersed P(St-MAA)seed particles with the diameter of 150 nm and the P(St-MAA)/P(St-NaSS)core/shell latexes with the particle size of about 200 nm were synthesized. When the 25/75 mole ratio of NaSS/(St+MAA)and 2 mol% of BAA were used in the seeded emulsion polymerization, the resulted P(St-MAA)/P(St-NaSS) latex product showed a low weight loss after water extraction, and the NaSS unit content in the whole particle and in the shell reached 11.7 mol% and 34.6 mol%, respectively.
Synthesis and structure determination of pyrazine-containing macrocyclic polyazomethines
Liang Chun Wu , Long Qing Liu , Hai Shan Jin , Ming Liang Ma , Xiao Li Zhao , Ke Wen
2010, 21(10): 1263-1266  doi: 10.1016/j.cclet.2010.05.017
[Abstract](34) [FullText HTML] [PDF 816KB](0)
Abstract:
Two pyrazine-containing macrocyclic polyazomethines 2 and 3 were synthesized by direct[2+2]and[3+3]condensation reactions between 2, 2'-[pyrazine-2, 3-diylbis(oxy)]dibenzaldehyde (1) and hydrazine. Both 2 and 3 were characterized by NMR, HRMS, and their structures were determined via X-ray crystal diffraction studies.
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