2011 Volume 22 Issue 6

Nano-TiO2:An eco-friendly alternative for the synthesis of quinoxalines
Bi Bi Fatemeh Mirjalili , Ali Akbari
2011, 22(6): 573-756  doi: 10.1016/j.cclet.2010.12.016
[Abstract](230) [FullText HTML] [PDF 487KB](0)
Abstract:
Nano-TiO2 as an eco-friendly and efficient nanocatalyst was applied for quinoxaline preparation with improved yield.In this protocol, diketones and 1.2-diamines were condensed in the presence of catalyst at room temperature.
Total synthesis of cyclic heptapeptide euryjanicin B
Chun Mei Zhang , Jun Xiang Guo , Liang Wang , Xiao Yun Chai , Hong Gang Hu , Qiu Ye Wu
2011, 22(6): 631-634  doi: 10.1016/j.cclet.2010.12.039
[Abstract](213) [FullText HTML] [PDF 253KB](0)
Abstract:
The first synthesis of the naturally occurring cyclic peptide euryjanicin B has been achieved.A general method was described to synthesize the cyclic peptide by a two-step solid-phase/solution synthesis strategy.All the amino acids in this study are L-configuration, The linear heptapeptide was assembled by standard Fmoc chemistry on solid-phase and subsequently cyclization was carried out by solution method.
Efficient synthesis of hydroxyl functioned polyesters from natural polyols and sebacic acid
Zhuo Yuan Ning , Qing Shan Zhang , Qin Pei Wu , Yun Zheng Li , Dong Xia Ma , Jia Zhe Chen
2011, 22(6): 635-638  doi: 10.1016/j.cclet.2010.12.033
[Abstract](211) [FullText HTML] [PDF 200KB](0)
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Amphiphilic hydroxyl functioned polyester(HFP)can be used as compatibilizers for blends of starch and resins.We developed a synthetic method for effective preparation of HFPs.Water was removed by high flow rate N2 rather than high vacuum during polycondensation of sebacic acid with xylitol, sorbitol, or mannitol in the presence of dehydrative condensation catalyst and the product is with [η] of 27.2 mL/g, Mn of 1903, Mw of 167,693, Tg of-30.5 ℃, Tm of 44.0 ℃.Weight loss is 1.73% under 200 ℃.The integral distributions of molecular weight are 43.6 wt% and 63.8 wt% over 10,000 and 3000, respectively.The results indicated that higher molecular weight HFP was economically synthesized.
Synergistic catalysis of isolated Fe3+ and Fe2O3 on FeOx/HZSM-5 catalysts for Friedel-Crafts benzylation of benzene
Tao Lin , Xin Zhang , Rong Li , Ting Bai , Si Ying Yang
2011, 22(6): 639-642  doi: 10.1016/j.cclet.2010.12.034
[Abstract](220) [FullText HTML] [PDF 355KB](0)
Abstract:
FeOx/HZSM-5 catalyst with 8 wt.% Fe-loading(8-FeZ)exhibited significantly higher reactivity in the benzylation of benzene with benzyl chloride than FeOx/HZSM-5 catalyst with 2.5 wt.% Fe-loading(2.5-FeZ)because the synergistic catalysis between isolated Fe3+ and superfine Fe2O3 occurred on 8-FeZ in the reaction.
Preparation and application of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide
Xiu Juan Feng , Mei Yan , Xin Zhang , Ming Bao
2011, 22(6): 643-646  doi: 10.1016/j.cclet.2010.12.044
[Abstract](213) [FullText HTML] [PDF 820KB](0)
Abstract:
A new method for the preparation of SB A-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide was presented.The newly formed SBA-15-supported palladium catalyst(Ph-SBA-15-PPh3-Pd)exhibited high catalytic activity for the Heck reaction of 4-nitrobromobenzene with methyl acrylate.The catalyst can be reused several times without a loss of activity.
Off-on-off luminescent switching of a dye containing imidazo [4, 5-f] [1, 10]phenanthroline
Hai Guang Zhang , Xu Tang Tao , Kao Shan Chen , Chun Xue Yuan , Shi Na Yan , Min Hua Jiang
2011, 22(6): 647-650  doi: 10.1016/j.cclet.2010.12.005
[Abstract](222) [FullText HTML] [PDF 746KB](0)
Abstract:
A new acid-base fluorescent switch containing both imidazo [4,5-f] [1,10]-phenanthroline and triphenylamine groups has been synthesized.Its fluorescence emissions and absorptions can be reversibly changed through protonation/deprotonation of imidazole and amine moiety by controlling the intramolecular charge transfer(ICT)process, leading to off-on-off fluorescent molecular switching.
A novel simple bifunctional catalyst for the direct aldol reaction
Chang Lu Liu , Hao Zhang , Ning Wang
2011, 22(6): 651-654  doi: 10.1016/j.cclet.2010.12.025
[Abstract](182) [FullText HTML] [PDF 202KB](0)
Abstract:
A new acid-base fluorescent switch containing both imidazo[4,5-f][1,10]-phenanthroline and triphenylamine groups has been synthesized.Its fluorescence emissions and absorptions can be reversibly changed through protonation/deprotonation of imidazole and amine moiety by controlling the intramolecular charge transfer(ICT)process, leading to off-on-off fluorescent molecular switching.
Cerium(IV)ammonium nitrate(CAN)initiated O-alkylation of oximes with N-vinyl lactams
Jian Tao Wang , Xiao Dong Jia , Li Jun Peng , Long Min Wu
2011, 22(6): 655-658  doi: 10.1016/j.cclet.2010.12.027
[Abstract](183) [FullText HTML] [PDF 205KB](0)
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O-Alkylation of oximes with N-vinylpyrrolidin-2-one or iV-methyl-N-vinylacetamide was efficiently initiated by a catalytic amount of cerium(IV)ammonium nitrate(CAN), giving the corresponding oxime ether derivatives in good yield.
A novel and efficient synthesis of alkyl thiocyanates from alkyl halides in water using phase transfer catalysts
Maryam Gorjizadeh , Soheil Sayyahi
2011, 22(6): 659-662  doi: 10.1016/j.cclet.2010.11.025
[Abstract](185) [FullText HTML] [PDF 248KB](0)
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1,4-Bis(triphenylphosphonium)-2-butene dichloride(BTPBDC)and 1,4-bis(triphenyl phosphonium)-2-butene dithiocyanate(BTPBDT)were prepared and used as phase-transfer catalysts.Alkyl halides were converted efficiently to the corresponding alkyl thiocyanates under mild reaction conditions in water.No evidence for the formation of isothiocy anates as by-product of the reaction was observed.
Synthesis and bioactivity of novel coumarin derivatives containing(E)-methyl 2-(methoxyimino)-2-phenylacetates
Ai Ying Guan , Chang Ling Liu , Zhi Nian Li , Ming Xing Zhang
2011, 22(6): 663-666  doi: 10.1016/j.cclet.2010.12.028
[Abstract](191) [FullText HTML] [PDF 231KB](0)
Abstract:
Ten coumarin derivatives containing(E)-methyl 2-(methoxyimino)-2-phenylacetate were synthesized and bioassayed.The compounds were identified by IR, 1H NMR and elemental analyses.The test results indicated that compound 5j(R1 is methyl and R2 is n-C6H13)was the optimal structure in this paper with good fungicidal activity against CDM(85%)at 6.25 mg/L concentration.
Radical cation salts induced domino reaction of anilines with enol ethers:Synthesis of 1,2,3,4-tetrahydroquinoline derivatives
Xiao Dong Jia , Yan Ren , Cong Dde Huo , Wen Juan Wang , Xiang Ning Chen , Qiong Fu , Xi Cun Wang
2011, 22(6): 671-674  doi: 10.1016/j.cclet.2010.12.038
[Abstract](192) [FullText HTML] [PDF 318KB](0)
Abstract:
A domino reaction of anilines with cyclic and acyclic enol ethers induced by catalytic amounts of TBPA·+(5 mol%)was investigated and a series of 2,4-disubstituted-1,2,3,4-tetrahydroquinolines were synthesized.Different from cyclic enol ethers, when acyclic enol ethers were used in the reaction, they serve as surrogates of acetaldehyde, producing a series of 2-methyl-4-anilino-1,2,3,4-tetrahydroquinolines.A single electron transfer mechanism was proposed to rationalize the products formation.
An efficient method for the N-arylation of phenylurea via copper catalyzed amidation
Sandip N.Gavade , Ravi S.Balaskar , Madhav S.Mane , Pramod N.Pabrekar , Murlidhar S.Shingare , Dhananjay V.Mane
2011, 22(6): 675-678  doi: 10.1016/j.cclet.2010.12.018
[Abstract](174) [FullText HTML] [PDF 196KB](0)
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The coupling reaction of phenylurea with different functionalized aryl halides in the presence of air stable Cul, N,N-dimethylethylenediamine as a ligand, and K3PO4 as a base gives symmetrical and unsymmetrical diarylureas in relatively high yields.This method is milder than the palladium catalyzed arylation and avoids the use of toxic phosphine ligands.
Efficient synthesis and biological evaluation of 4-arylcoumarin derivatives
Jie Sun , c , Wei Xian Ding , Ke Yun Zhang , Yong Zou
2011, 22(6): 677-670  doi: 10.1016/j.cclet.2010.12.017
[Abstract](177) [FullText HTML] [PDF 240KB](0)
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Two bioactive natural 4-arylcoumarins, 5,7,4'-trimethoxy-4-phenylcoumarin(1a), 5,7-dimethoxy-4-phenylcoumarin(1b)and five closely related derivatives 1c-g were synthesized.In vitro evaluation with a catechol subunit for antioxidant and antimicrobial activity, these compounds using standard methods showed that compounds 1d, 1f displayed promise radical scavenging activity and 1f was found to be the most active one against Bacillus dysenteriae.
Intermolecular cyclocondensation reaction of 3,4-dihydropyrimidine-2-thione under the Mitsunobu reaction conditions
Yu Xia Da , Zhang Zhang , Zheng Jun Quan
2011, 22(6): 679-682  doi: 10.1016/j.cclet.2010.12.041
[Abstract](189) [FullText HTML] [PDF 274KB](0)
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A self-intermolecular cyclocondensation reaction of 3,4-dihydropyrimidine-2-thione(DHPM)to give a novel tricyclic structure containing DHPM core in the presence of diethyl azodicarboxylate(DEAD)and triphenylphosphine(TPP)at room temperature is reported.
Fe/MCM-41 as a promising heterogeneous catalyst for ozonation of p-chlorobenzoic acid in aqueous solution
Rui Huan Huang , Jie Liu , Lai Sheng Li , Qiu Yun Zhang , Li Xuan Zeng , Ping Lu
2011, 22(6): 683-686  doi: 10.1016/j.cclet.2010.11.037
[Abstract](190) [FullText HTML] [PDF 247KB](0)
Abstract:
Mesoporous MCM-41 and Fe loaded MCM-41(Fe/MCM-41), which were successfully prepared by a hydrothermal method and a dipping method respectively, were applied as heterogeneous catalysts for ozonation of p-chlorobenzoic acid(p-CBA)in aqueous solution.MCM-41 and Fe/MCM-41 were characterized by XRD, FT-IR and diffuse reflectance UV-vis(DR-UV-vis)techniques.The presence of either MCM-41 or Fe/MCM-41 improves p-CBA and total organic carbon(TOC)removal efficiency compared to ozonation alone.Under the experimental condition, TOC removal rate of Fe/MCM-41/O3 process is over 63.5% at 60 min oxidation time, 44.5% using MCM-41 as catalyst, only 37.7% with ozonation alone.The presence of /erf-butanol(TBA)in the Fe/MCM-41/ O3 process indicated that the oxidation mechanism of ρ-CBA occurs via OH in the liquid bulk.And Fe/MCM-41 is a promising catalyst.
Cesium hydroxide-catalyzed hydrothiolation of alkynyl selenides to highly stereo- and regioselectively synthesize(Z)-1-organoseleno-2-arylthio-1-alkenes
Ai He Yu , Ren Hua Qiu , Nian Yuan Tan , Li Feng Peng , Xin Hua Xu
2011, 22(6): 687-690  doi: 10.1016/j.cclet.2010.12.050
[Abstract](186) [FullText HTML] [PDF 194KB](0)
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In the presence of catalytic amount of cesium hydroxide the hydrothiolation of alkynyl selenides occurred at room temperature in DMF under nitrogen atmosphere to give exclusive(Z)-1-organoseleno-2-arylthio-1-alkene in excellent yields.It could provide a new and expedient way for the preparation of(Z)-1-arylseleno-2-arylthio-1-alkene.
An efficient oxidation of benzylic and alicylic compounds with water-soluble copper catalysts in t-butyl hydroperoxide at room temperature
Ateeq Rahman , S.M.Al Zahrani , Abdel Aziz Nait Ajjou
2011, 22(6): 691-693  doi: 10.1016/j.cclet.2010.12.035
[Abstract](201) [FullText HTML] [PDF 154KB](0)
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The water soluble catalytic system comprising of CuCl2 and 2,2-biquinoline-4,4-dicarboxylic acid dipotassium salt(BQC)is highly efficient organic metallic catalysts for selective oxidation of benzylic and alicyclic compounds to the corresponding ketones, ex:indan to indanone, ethyl benzene to acetophenone.
Pyromeconic acid derivatives from Conyza canadnsis(L.)Cronq
Bai Lian Liu , Guo Cai Wang , Hong Li Liu , Yi Dai , Wen Cai Ye , Yao Lan Li
2011, 22(6): 694-696  doi: 10.1016/j.cclet.2010.12.023
[Abstract](202) [FullText HTML] [PDF 227KB](1)
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A new pyromeconic acid derivative, pyromeconic acid-3-O-β-D-glucopyranoside-3'-(O-β-D-glucopyranoside)-6'-(O-4"-hydro-xybenzoate)(1), along with two known ones, were isolated from the whole plants of Conyza canadensis.Their structures were elucidated based on the analysis of their spectroscopic data.The in vitro antibacterial testing results showed that all of these three compounds were inactive towards two bacterial strains, Escherichia coli and Staphyloccocus aureus.
Triterpene saponins with XOD inhibitory activity from the roots of Ilex pubescens
Li Ping Lin , Wei Qu , Jing Yu Liang
2011, 22(6): 697-700  doi: 10.1016/j.cclet.2010.12.045
[Abstract](187) [FullText HTML] [PDF 211KB](0)
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A new triterpene saponin with 28-nor-urs-12(13),18(17)-dien-3β-ol as aglycone, named ilexsaponin C(1)was isolated from the roots of Ilex pubescens, together with three known saponins 2, 3 and 4.The structure of 1 was elucidated on the basis of spectral analysis including ID and 2D NMR and HR-ESI-MS.Saponins 1 and 4 exhibited significant XOD inhibitory activity in the test.
N1,N2-Bis [1-(2-hydroxyphenyl)methylidene]ethanedihydrazide as a neutral ionophore for preparation of a new Ho3+ PVC-membrane sensor
Hassan Ali Zamani
2011, 22(6): 701-704  doi: 10.1016/j.cclet.2010.10.056
[Abstract](187) [FullText HTML] [PDF 403KB](0)
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N1,N2-Bis [1-(2-hydroxyphenyl)methylidene]ethanedihydrazide(MEH)was used as new compound which plays the role of an excellent ion carrier in the fabrication of a Ho(Ⅲ)membrane electrode.The electrode shows a good selectivity for Ho(Ⅲ)ion with respect to most common cations including alkali, alkaline earth, transition and heavy metal ions.This electrode has a wide linear dynamic range from 1.0×10-6 to 1.0×10-2 mol/L with a Nernstian slope of 19.8±0.3 mV per decade and a low detection limit of 5.8×10-7 mol/L in the pH range of 2.5-9.8, while the response time was rapid( < 10 s).The suggested sensor was applied to the determination of Ho(Ⅲ)ions in tap water and river water samples.
Electrocatalytic determination of epinephrine and uric acid using a novel hydroquinone modified carbon paste electrode
Mohammad Mazloum-Ardakani , Zahra Taleat , Hadi Beitollahi , Hossein Naeimi
2011, 22(6): 705-708  doi: 10.1016/j.cclet.2010.11.035
[Abstract](184) [FullText HTML] [PDF 328KB](0)
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A sensitive and selective electrochemical method for the determination of epinephrine(EP)was developed using a modified carbon paste electrode(MCPE)with 2,2'- [3,6-dioxa-l,8-octanediylbis(nitriloethylidyne)]-bis-hydroquinone(DOH).Cyclic vol-tammetry was used to investigate the redox properties of this modified electrode at various solution pH values and at various scan rates.In differential pulse voltammetry, the modified electrode could separate the oxidation peak potentials of EP and uric acid(UA)present in the solution but at the unmodified CPE the peak potentials were indistinguishable.This method was also examined for determination of EP in EP injection.
Effect of temperature on the ML of Au doped(Zn,Cd)S mixed phosphor
Jagjeet Kaur , N.S.Suryanarayana , Vikas Dubey
2011, 22(6): 709-712  doi: 10.1016/j.cclet.2010.12.006
[Abstract](186) [FullText HTML] [PDF 302KB](0)
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In this paper the effect of temperature on the mechanoluminescence of Au doped phosphors of(Zn,Cd)S is described.It is found that the ML disappears beyond a particular temperature.The temperature dependence of ML intensity follows the relationiI=IT0(1-T/TC)n, where IT0 is a constant, n is the slop of log IT versus log(1- T/TC)plot which lies between 0.9 and 1.10, TC is the temperature at which ML disappear.It is found that the ML intensity in(Zn,Cd)S:Au disappear at 600 K.
Electrochemical behavior of Ru(H2bpp)2(PF6)2 and its interaction with bovine serum albumin(BSA)
Qiao Hua Wei , Li Jing Han , Jing Hua Chen , Fang Nan Xiao , Shen Liang Zeng , Guo Nan Chen
2011, 22(6): 713-716  doi: 10.1016/j.cclet.2010.12.040
[Abstract](201) [FullText HTML] [PDF 275KB](0)
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In this paper, it was found that Ru(H2bpp)2(PF6)2(H2bpp=2,6-bis(pyrazol-3-yl)pyridine)complex had excellent electrochemical activity at the carbon paste electrode in the buffer solution of Tris-HCl(pH 7.0)with a couple reversible redox peaks at 0.296 V and 0.348 V, respectively.Voltammetry was used to investigate the electrochemical behavior of Ru(H2bpp)2(PF6)2 and the interaction between Ru(H2bpp)2(PF6)2 and bovine serum albumin(BSA).In the present of BSA, the oxidation peak current of Ru(H2bpp)2(PF6)2 complex was decreased linearly and the decrease of oxidation peak current of Ru(H2bpp)2(PF6)2 is proportional to BSA concentration from 0.1 to 2.5 mg/L with a detection limit 0.02 mg/L.
Interaction between Janus Green B and bovine serum albumin:Electrochemistry and spectroscopy studies
Neslihan ö zdemir , Serkan ö zdemir , Ender Biçer
2011, 22(6): 717-720  doi: 10.1016/j.cclet.2010.12.007
[Abstract](194) [FullText HTML] [PDF 404KB](0)
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In this study, voltammetric and spectroscopic investigation of the interaction between Janus Green B(JGB)and bovine serum albumin(BSA)was reported.The interaction was observed at Britton-Robinson buffer(pH 7.0).When JGB was added to solution containing BSA, the peak currents of BSA decrease with the increasing of JGB concentrations which is due to the interaction of JGB and BSA.The binding constant of JGB with BSA was obtained by voltammetric data.Also, this interaction was supported by means of UV-vis spectroscopic measurements.The UV-vis absorption spectra of JGB in the presence of BSA decrease with the increasing of BSA concentrations.
A novel method to prepare SPR sensor chips based on photografting molecularly imprinted polymer
Qing Quan Wei , Tian Xin Wei
2011, 22(6): 721-724  doi: 10.1016/j.cclet.2010.11.024
[Abstract](190) [FullText HTML] [PDF 509KB](0)
Abstract:
A novel method to prepare surface plasmon resonance(SPR)sensor chips based on grafted imprinted polymer is explored.Benzophenone photografting system is used to grow molecularly imprinted polymer(MIP)films from the modified surface of gold substrate.The surface morphology and thickness of MIP films were investigated by scanning electronic microscope(SEM).The adsorption properties of sensor chip were studied by SPR spectroscopy.The results demonstrate that nano-MIP films can be constructed on the surface of gold substrate with the good adsorption of template molecules.
A novel chemosensor-bipyridyl end capped hyperbranched conjugated polymer
Xin Meng , Qing Guo He , Hui Min Cao , Jian Gong Cheng
2011, 22(6): 725-728  doi: 10.1016/j.cclet.2010.12.024
[Abstract](170) [FullText HTML] [PDF 389KB](0)
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A novel hyperbranched conjugated chemosensor with bipyridyl groups as periphery groups(BPY-HPV)was synthesized.BPY-HPV was highly sensitive to metal ions(Cu2+, Ni2+)for the strong coordination interaction(Ksv at the order of 107 mol-1 L)monitored by fluorescence spectroscopy.Moreover, by hydrogen bonds and charge transfer interaction, BPY-HPV shows strong interaction with 1,1,2,2-tetrachloroethane whatever in CH2C12(Ksv~106 mol-1 L)or film.
Study on electrochemical fingerprints of different Chrysanthemums by using B-Z oscillation system
Wang Xing Cheng , Jia Chen , Cheng Wu Fang , De Ling Wu
2011, 22(6): 729-732  doi: 10.1016/j.cclet.2010.12.047
[Abstract](196) [FullText HTML] [PDF 286KB](0)
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A sensitive and convenient method for the study of electrochemical fingerprints of Chrysanthemums from different regions is studied by Belousov-Zhabotinskii(B-Z)oscillation system with malonate as a dissipative material.The results indicated that the electrochemical fingerprints of Chrysanthemums from different regions show significantly different characteristics, and can be used to identify the regions of Chrysanthemums.
Hydrolysis kinetics of benzyl phenyl ether in high temperature liquid water
Xiao Yu Wu , Xiu Yang Lü
2011, 22(6): 733-737  doi: 10.1016/j.cclet.2010.12.026
[Abstract](203) [FullText HTML] [PDF 305KB](1)
Abstract:
The application of high temperature liquid water(HTLW)to decomposition of lignin as efficient and green solution for phenolic compounds recovery was studied.Benzyl phenyl ether(BPE), the lignin model compound, was treated at temperatures ranging from 220 to 250 8C.BPE undergo hydrolysis in HTLW, and main products were phenol and benzyl alcohol with the minimum selectivities of 75.7% and 82.8%, respectively.Lower temperature led to higher selectivity in 220-250 8C temperature range.The kinetics on BPE hydrolysis was studied and the activation energy was determined as 150.3±12.5 kJ/mol with the first-order kinetic equations.Based on products distribution, the reaction mechanism for decomposition of benzyl phenyl ether was proposed.The investigated process provides insights into the design of a commercial method for utilization of lignin.
Amide as an efficient ligand in the palladium-catalyzed Suzuki coupling reaction in water/ethanol under aerobic conditions
Hai Yang Liu , Kun Wang , Hai Yan Fu , Mao Lin Yuan , Hua Chen , Rui Xiang Li
2011, 22(6): 738-740  doi: 10.1016/j.cclet.2010.12.048
[Abstract](180) [FullText HTML] [PDF 220KB](1)
Abstract:
Amide, which is derived from proline and is inexpensive and air-stable, has been synthesized and characterized by 1H NMR,13C NMR, and MS.It was found to be an efficient ligand in the palladium-catalyzed Suzuki cross-coupling reaction.In the Pd/amide catalytic system, aryl bromides can be coupled with phenylboronic acid in ethanol/water(1:2;v/v)in excellent yields even with a low Pd loading of 0.01 mol%.Moreover, the scope of the reaction is broad, and a wide variety of functional groups are tolerant.
Ethylene glycol aluminum as a novel catalyst for the synthesis of poly(ethylene terephthalate)
Bin Xiao , Li Ping Wang , Ren Hao Mei , Gong Ying Wang
2011, 22(6): 741-744  doi: 10.1016/j.cclet.2010.12.036
[Abstract](195) [FullText HTML] [PDF 252KB](2)
Abstract:
Ethylene glycol aluminum was prepared efficiently and characterized by FT-IR and NMR.It exhibited higher catalytic activity and had profitable effect than titanium glycolate and ethylene glycol antimony for the synthesis of poly(ethylene terephthalate)(PET).It was only used as polycondensation catalyst because it was sensitive to water.For this catalyst, the degree of esterification of the theoretical amount of water was produced up to 95% at 260 ℃, while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PET polyester, polymerized at 280℃, 70 Pa for 39 min, was 0.87 dL/g and 23.0 μmol/g, respectively.Ethylene glycol aluminum was a promising catalyst for the synthesis of PET polyester.
Dielectric analysis on phase transition and micelle shape of polyoxyethylene trisiloxane surfactant in dilute aqueous solution
Ya Wen Zhou , Wei Zhou , Fu Han , Bao Cai Xu
2011, 22(6): 745-748  doi: 10.1016/j.cclet.2010.12.01
[Abstract](184) [FullText HTML] [PDF 830KB](0)
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The cloudy Silwet L-77 aqueous solution on the concentration range from 0.5% to 50% was investigated by dielectric relaxation spectroscopy.The concentration dependence of phase microstructure was confirmed by means of analyzing the dielectric parameters of bulk solution.The relaxation behavior was assigned to the interfacial polarization between the micelle and the medium, and the relaxation distribution parameter was used to figure the shape transition from sphere to ellipsoid with the concentration increasing.The synchronous reduction of permittivity and conductivity indicated the formation of the lamellar phase.As compensation, the quantity of the surfactant liquid phase gradually decreased, whose shape constantly kept ellipsoidal.
Synthesis of polyethylenimine grafted with copolymers of polyethylene glycol and polycaprolactone and its potential for siRNA delivery
Wei Huang , Ming Lv , Zhong Gao Gao
2011, 22(6): 749-752  doi: 10.1016/j.cclet.2010.12.057
[Abstract](180) [FullText HTML] [PDF 295KB](0)
Abstract:
Copolymers mPEG-PCL were prepared and grafted onto polyethylenimine(PEI)to synthesize copolymers mPEG-PCL-g-PEI with low cytotoxicity.The mPEG-PCL-g-PEI could condense siRNA to form nanoparticles with positive zeta potential.These nanoparticles could delivery siRNA into cells to effectively inhibit the expression of target gene, which suggested that mPEG-PCL-g-PEl could serve as a highly efficient vector for siRNA delivery.
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