2007 Volume 18 Issue 8

Synthesis of 4"-benzyloxyimino-4"-deoxyavermectin B1a derivatives
Yue Mei Jia , Xiao Mei Liang , Xue Qin Fang , Jing Ping Wu , Dao Quan Wang , Chang Hui Rui , Xian Lin Fan , Hai Yan Zhao , Yun Xia Wang
2007, 18(8): 895-898  doi: 10.1016/j.cclet.2007.06.003
[Abstract](144) [FullText HTML] [PDF 210KB](0)
Six new 4"-benzyloxyimino-4"-deoxyavermectin B1a derivatives were synthesized from avermectin B1a by the selective protection of C-5-hydroxy group, oxidation of C-4"-hydroxy group, and deprotection followed by reaction with O-substituted hydroxylamine hydrochlorides. Their structures were confirmed by IR, 1H NMR, 13C NMR and MS. Insecticidal activities of the derivatives against Phopalosiphum pseudobrassicae, Spodoptera exigua and Pluteua xylosteua were evaluated.
Synthesis and preliminary cytotoxic evaluation of substituted indoles as potential anticancer agents
Chang Qing Shi , Zhang Qin Liu , Wen Qing Lin , Yuan Wei Chen
2007, 18(8): 899-901  doi: 10.1016/j.cclet.2007.05.052
[Abstract](247) [FullText HTML] [PDF 217KB](0)
A variety of indole derivatives were designed, synthesized and preliminarily evaluated for their in vitro cytotoxic activity in the A431 and H460 cell lines. All the compounds examined conferred unusual potency in a tumor cell cytotoxicity assay. The findings showed the indole derivatives would be a promising candidate for the development of new anticancer agents.
Total synthesis of human urotension-Ⅱ by microwave-assisted solid phase method
Hui Bin Zhang , Yu Shi Chi , Wen Long Huang , Shuai Jian Ni
2007, 18(8): 902-904  doi: 10.1016/j.cclet.2007.06.002
[Abstract](144) [FullText HTML] [PDF 279KB](0)
Human urotension-Ⅱ was synthesized efficiently on Wang resin under microwave irradiation using Fmoc/tBu orthogonal protection strategy. Disulphide bridge was formed on solid phase with the irradiation of microwave, then the whole peptide was cleaved from the resin. The purity of crude peptide cyclized under microwave irradiation was higher than that under room temperature.
Synthesis of 1-aryl-3-(3, 4-dihydro-2H-chromen-5-yl)ureas as TNF-α inhibitors
Xin Ming Zhou , Zhi Bing Zheng , Hong Ying Liu , Wu Zhong , Jun Hai Xiao , Li Li Wang , Song Li
2007, 18(8): 905-908  doi: 10.1016/j.cclet.2007.06.014
[Abstract](144) [FullText HTML] [PDF 227KB](0)
A new series of compounds, 1-aryl-3-(3, 4-dihydro-2H-chromen-5-yl) ureas, have been synthesized and their structures were confirmed by FAB-MS and 1H NMR. The preliminary pharmacological screening showed that these compounds inhibited TNF-α production in lipopolysaccharide (LPS)-stimulated THP-1 cells.
Silica triflate as an efficient reagent for the solvent-free synthesis of coumarins
Farhad Shirini , Katayoun Marjani , Hossein Taherpour Nahzomi , Mohammad Ali Zolfigol
2007, 18(8): 909-911  doi: 10.1016/j.cclet.2007.05.051
[Abstract](228) [FullText HTML] [PDF 209KB](0)
Silica triflate, as a new silica-based reagent, can be used for the efficient synthesis of 4-substituted coumarins via a Pechmann reaction under solvent-free reaction conditions. All reactions were performed at 80℃ in good to high yields.
Synthesis and structure characterization of novel calix[4](aza)crown derivatives
Zhi Qiang Shi , Ya Qing Feng , Wen Xiang Wang , He Wen Wang
2007, 18(8): 912-914  doi: 10.1016/j.cclet.2007.06.004
[Abstract](218) [FullText HTML] [PDF 312KB](0)
Three novel calix[4](aza)crown deravatives have been synthesized, including a new [2] pseudorotaxane in which calix[4]-azacrown behaves as a stopper, a novel ‘tren’ type calix [4] azacrown and a novel ‘spiro’ type calix [4] azacrown containing morpholine unit. The structures of these compounds have been confirmed by NMR and MS.
Synthesis of 12-alkoxycarbonylmethylene-1, 15-pentadecanolides
Jian Jun Li , Shu Hui Jin , Xiao Mei Liang , De Kai Yuan , Dao Quan Wang
2007, 18(8): 915-916  doi: 10.1016/j.cclet.2007.05.042
[Abstract](152) [FullText HTML] [PDF 205KB](0)
Six novel 12-alkoxycarbonylmethylene-1, 15-pentadecanolides (3) were synthesized from 2-nitrocyclo-dodecanone by the Michael addition with acrolein followed by ring enlargement, Nef reaction and Wittig-Horner reaction. Their structures were confirmed by 1H NMR, IR and elemental analysis. The preliminary bioassay showed that they have some fungicidal activity.
An alternative synthetic approach towards erythrinan and homoerythrinan alkaloids by tandem semipinacol/intramolecular Schmidt reaction
Pei Ming Gu , Yu Ming Zhao , Yong Qiang Tu , Min Wang , Shu Yu Zhang
2007, 18(8): 917-919  doi: 10.1016/j.cclet.2007.05.029
[Abstract](153) [FullText HTML] [PDF 248KB](1)
An alternative construction of A-B-D ting-system of erythrinan and homoerythrinan alkaloids by TiCl4-mediated tandem semipinacol/intramolecular Schmidt reaction of α-siloxyepoxyazide was addressed and the unusual epoxidation stereoselectivity was observed in preparation of the substrate once again.
Synthesis and properties of a star-shaped organic material with triphenylamine and N-vinyl carbazole units
Qing Guo He , Jian Gong Cheng , Feng Lian Bai
2007, 18(8): 920-922  doi: 10.1016/j.cclet.2007.05.055
[Abstract](188) [FullText HTML] [PDF 1692KB](0)
A starburst triphenylamine cored N-vinyl carbazole (V-Cz) branched compound was designed and synthesized via optimized Heck reaction in a yield of 40-60%. Moderate yield came from decomposition of V-Cz and self-coupling of triiodo-triphenylamine.TCz-TPA adopts a highly twisted propeller conformation by molecular mechanical optimization. It is readily soluble for its highly twisted conformation. Transparent and pinhole free films could be easily fabricated by spin-coating for its starburst structure. It emits blue-greenish light in CH2Cl2 peaked at 460 nm with a narrow full-width at half-maximum (FWHM) of 65 nm. As compared, the absorption peaks of the spin-coated film blue shifted and emission peak red shifted to 510 nm with a FWHM of 96 nm.
The synthesis and bioevaluation of the dicyclic arene-homospermidine conjugates
Peng Fei Cheng , Jian Hong Wang , Song Qiang Xie , Jin Zhao , Chao Jie Wang
2007, 18(8): 923-925  doi: 10.1016/j.cclet.2007.05.053
[Abstract](243) [FullText HTML] [PDF 209KB](0)
Four novel dicyclic arene-homospermidine conjugates (6a-d) were synthesized and evaluated for cytotoxicity in L1210, α-difluoromethylornithine (DFMO) treated L1210, melanoma B 16, spermidine (SPD) treated B 16, and Hela cells. In the DFMO-treated L1210 experiments, 6a-d were more sensitive to DFMO than naphthalene-homospermidine (6e), suggesting that 6a-d can utilize the polyamine transporter (PAT) to enter the cells as well as 6e. The diminished cytotoxicity in the SPD/B 16 experiments also supported this conclusion. In summary, the homospermidine is an efficacious vector to ferry dicyclic arenes into cells via PAT.
Aerobic oxidation of benzylic aldehydes to acids catalyzed by iron (Ⅲ) meso-tetraphenylporphyrin chloride under ambient conditions
Xian Tai Zhou , Hong Bing Ji , Qiu Lan Yuan , Jian Chang Xu , Li Xia Pei , Le Fu Wang
2007, 18(8): 926-928  doi: 10.1016/j.cclet.2007.05.031
[Abstract](135) [FullText HTML] [PDF 176KB](0)
Highly efficient aerobic oxidation of benzylic aldehydes to the corresponding acids catalyzed by iron (Ⅲ) meso-tetraphenylporphyrin chloride (Fe(TPP)Cl) under ambient conditions was developed. The catalyst has been proved to be an excellent catalyst for the system in the presence of molecular oxygen and isobutryaldehyde at room temperature.
Lipase immobilized on HOOC-MCF: A highly enantioselective catalyst for transesterification resolution of (R, S)-1-phenylethanol
Ping Xue , Xiang Hui Yan , Zheng Wang
2007, 18(8): 929-932  doi: 10.1016/j.cclet.2007.06.005
[Abstract](142) [FullText HTML] [PDF 227KB](0)
Pseudomonas cepacia lipase (PSL) immobilized on the carboxyl-functionalized meso-cellular foams (HOOC-MCF) was used for the transesterification resolution of (R, S)-1-phenylethanol in organic solvent. The results showed that the ee value of (S)-1-phenylethanol and (R)-1-phenylethyl acetate reached 99% with 50% conversion of 1-phenylethanol using toluene as solvent.Furthermore, it was found that PSL/HOOC-MCF exhibited high enantioselectivity in organic solvent with log P≤2 such as toluene and hexane.
A novel phosphate ligand used for the Rh-catalyzed hydroformylation of cyclohexene in a thermoregulated PEG biphase system
Wei Wei , Yan Hua Wang , Jing Yang Jiang , Zi Lin Jin
2007, 18(8): 933-935  doi: 10.1016/j.cclet.2007.05.044
[Abstract](250) [FullText HTML] [PDF 199KB](0)
A novel phosphate ligand, tri-(methoxyl polyethylene glycol)-phosphate (TMPGPA), has been synthesized and used in the Rhcatalyzed hydroformylation of cyclohexene in a thermoregulated PEG biphase system. Under the optimized conditions, pressure=5 Mpa (H2:CO=1:1), P/Rh=10 (molar ratio), reaction time=4 h and temperature=120℃, the conversion of cyclohexene and the yield of aldehyde are 99%. The catalyst retained in PEG phase can be easily separated from the organic phase containing product by simple phase separation and reused ten times without obvious loss in activity.
Efficient oxidation of benzyl alcohol with heteropolytungstate as reaction-controlled phase-transfer catalyst
Zhi Huan Weng , Jin Yan Wang , Xi Gao Jian
2007, 18(8): 936-938  doi: 10.1016/j.cclet.2007.06.007
[Abstract](238) [FullText HTML] [PDF 194KB](0)
A series of heteropolytungstates has been synthesized and utilized as catalysts to catalyze oxidation of benzyl alcohol with aqueous hydrogen peroxide. The results indicated that three of these catalysts showed the properties of reaction-controlled phasetransfer catalysis, and they had excellent catalytic ability to the oxidation of benzyl alcohol. No other by-products were detected by gas chromatography. Once the hydrogen peroxide was consumed completely, the catalyst precipitated from solvent, and the results of the catalyst recycle showed that the catalyst had high stability.
Interaction between N-phosphoryl-α-, β- and γ-amino acids and nucleosides
Li Ming Qiang , Shu Xia Cao , Yan Chun Guo , Xin Cheng Liao , Yu Fen Zhao
2007, 18(8): 939-942  doi: 10.1016/j.cclet.2007.05.032
[Abstract](147) [FullText HTML] [PDF 244KB](0)
The reactions of four different N-(O, O'-diisopropyl) phosphoamino acids (DIPP-aa), such as N-phosphoryl-L-α-alanine (DIPPL-α-Ala), N-phosphoryl-D-α-alanine (DIPP-D-α-Ala), N-phosphoryl-β-alanine (DIPP-β-Ala) and N-phosphoryl-γ-amino butyric acid (DIPP-γ-Aba), and four nucleosides, adenosine (A), guanosine (G), cytdine (C) and uridine (U), were studied by electrospray ionization tandem mass spectrometry (ESI-MS/MS) and HPLC/ESI-MS. DIPP-L-α-Ala and D1PP-D-α-Ala produced the same phosphorylated nucleosides, dinucleotides and phosphoroligopeptide. However, DIPP-β-Ala and DIPP-γ-Aba gave no relevant products.
Two new diarylheptanoids from the pericarps of Juglans regia L.
Jun Xi Liu , Duo Long Di , Xin Yi Huang , Chen Li
2007, 18(8): 943-946  doi: 10.1016/j.cclet.2007.05.028
[Abstract](142) [FullText HTML] [PDF 306KB](0)
Two new cyclic diarylheptanoids juglanin A (1) and juglanin B (2) were isolated from the pericarps of Juglans regia L. Their structures were elucidated by various spectroscopic methods including 2D NMR techniques (COSY, HMQC, HMBC, NOESY) and HR-ESIMS.
A new cyclostellettamine from sponge Amphimedon compressa
Nian Jun Xu , Xue Sun , Xiao Jun Yan
2007, 18(8): 947-950  doi: 10.1016/j.cclet.2007.06.006
[Abstract](152) [FullText HTML] [PDF 263KB](0)
A new compound, 8, 8'-dienecyclostellettamine, was isolated from the marine sponge Amphimedon compressa. Its structure was elucidated by spectroscopic methods including 1D and 2D NMR, UV, IR, ESI-MS, MALDI-MS techniques. It is probably an important precursor of the manzamine alkoids, and also showed vigorous antibacterial activities.
A new naphthoquinoneimine derivative from the marine algal-derived endophytic fungus Aspergillus niger EN-13
Yi Zhang , Xiao Ming Li , Chang Yun Wang , Bin Gui Wang
2007, 18(8): 951-953  doi: 10.1016/j.cclet.2007.05.054
[Abstract](148) [FullText HTML] [PDF 232KB](0)
Cultivation of an endophytic fungus Aspergillus niger EN-13 that was isolated from the inner tissue of the marine brown alga Colpomenia sinuosa resulted in the characterization of a new naphthoquinoneimine derivative, namely, 5, 7-dihydroxy-2-[1-(4-methoxy-6-oxo-6H-pyran-2-yl)-2-phenylethylamino]-[1, 4]naphthoquinone. The structure of the new compound was established on the basis of various NMR spectroscopic analyses including 2D NMR techniques, EI-MS, and HR-ESI-MS. This compound displayed moderate antifungal activity.
Fusarielin E, a new antifungal antibiotic from Fusarium sp.
Yue Gai , Ling Ling Zhao , Chang Qi Hu , Hui Ping Zhang
2007, 18(8): 954-956  doi: 10.1016/j.cclet.2007.05.048
[Abstract](130) [FullText HTML] [PDF 239KB](0)
A new antifungal antibiotic, fusarielin E, was isolated from the marine-derived fungus Fusarium sp. Its structure was established on the basis of various NMR spectroscopic analyses and HR-FAB-MS. Fusarielin E displayed significant biological activity against Pyricularia oryzae.
Two new brominated diterpenes from Laurencia decumbens
Nai Yun Ji , Xiao Ming Li , Chuan Ming Cui , Bin Gui Wang
2007, 18(8): 957-959  doi: 10.1016/j.cclet.2007.06.011
[Abstract](140) [FullText HTML] [PDF 236KB](0)
Two new brominated diterpenes, namely, laurendecumtriol and 11-deacetylpinnaterpene C, were isolated and identified from the marine red alga Laurencia decumbens. Their structures were established on the basis of various NMR spectroscopic techniques and HR-ESI-MS analyses.
Synthesis and characterization of poly(methyl methacrylate-co-polyhedral oligomeric silsesquioxane) hybrid nanocomposites
Ben Hong Yang , Hong Yao Xu , Cun Li , Shan Yi Guang
2007, 18(8): 960-962  doi: 10.1016/j.cclet.2007.05.041
[Abstract](140) [FullText HTML] [PDF 275KB](0)
A novel poly(methyl methacrylate-co-polyhedral oligomeric silsesquioxane) hybrid nanocomposite was synthesized by free radical polymerization and characterized by 1H NMR, 29Si NMR, and TGA technologies. Compared with PMMA homopolymer, the nanocomposite has better thermal stability.
Synthesis of EPR-g-styrene by anionic coupling technique
Xiang Li Xi , Zi Qiang Zhao , Qian Zhang , Yan Shi , Xiao Ping Cai , Zhi Feng Fu
2007, 18(8): 963-965  doi: 10.1016/j.cclet.2007.05.046
[Abstract](230) [FullText HTML] [PDF 250KB](0)
Ethylene-propylene rubber (EPR) graft copolymers were prepared successfully by anionic coupling technique between chlorinated EPR (Cl-EPR) and living anionic polystyrene chain. The EPR-g-styrene was characterized by hydrogen nuclear magnetic resonance (1H NMR) and gel penetration chromatogram (GPC).
Synthesis of polypiperazine-amide thin-film membrane on PPESK hollow fiber UF membrane
Fa Jie Yang , Da Ling Yang , Shou Hai Zhang , Xi Gao Jian
2007, 18(8): 966-968  doi: 10.1016/j.cclet.2007.05.047
[Abstract](142) [FullText HTML] [PDF 471KB](1)
A new interfacial polymerization (IP) procedure is developed in order to synthesize polypiperazine-amide thin-film membrane on the inner surface of poly(phthalazinone ether sulfone ketone) (PPESK) hollow fiber ultrafiltration (UF) membrane. A hollow fiber composite membrane with good performance was prepared and studied by FT-IR and scanning electron microscopy.
PS-HQ: More convenient in situ polymeric cocatalyst for the PdCl2-catalyzed acetalization in supercritical carbon dioxide
Zhao Yang Wang , Huan Feng Jiang , Chao Rong Qi , Yan Xia Shen , Shao Rong Yang
2007, 18(8): 969-972  doi: 10.1016/j.cclet.2007.05.026
[Abstract](139) [FullText HTML] [PDF 209KB](0)
Polystyrene-supported hydroquinone (PS-HQ) is presented as an in situ polymeric cocatalyst to replace polystyrene-supported benzoquinone (PS-BQ) in the PdCl2-catalyzed acetalization of methyl acrylate with methanol in supercritical carbon dioxide (scCO2) under oxygen atmosphere. Due to deletion of H2O2 oxidation step, PS-HQ is more convenient and relatively inexpensive.
Synthesis of a benzoxazine monomer containing maleimide and allyloxy groups
Yan Tang , Qing Lai Zhao , Ke Zeng , Pei Kai Miao , Ke Zhou , Wen Rui Tang , Hong Fei Zhou , Tao Liu , Yi Peng Wang , Gang Yang
2007, 18(8): 973-976  doi: 10.1016/j.cclet.2007.05.057
[Abstract](150) [FullText HTML] [PDF 274KB](3)
A novel benzoxazine monomer 3-(4-allyloxy)phenyl-3, 4-dihydro-2H-6-(N-maleimido)-1, 3-benzoxazine (AMB) was synthesized and structure was confirmed by FT-IR, 1H NMR. Thermal analysis (DSC) of AMB showed the introduction of allyloxy group decreased melting point and exhibited a narrow and symmetric curing exothermic window.
Photopolymerization induced by a benzophenone derivative photoinitiator
Ying Wang , Pu Xiao , Gang Qiang Wu , Su Qing Shi , Jun Nie
2007, 18(8): 977-980  doi: 10.1016/j.cclet.2007.06.012
[Abstract](154) [FullText HTML] [PDF 374KB](0)
A benzophenone derivative photoinitiator, HBP-TDI-HQ-TDI-HBP (HTCTH), was synthesized based on 4-hydroxy benzophenone (HBP), toluene-2, 4-diisocyanate (TDI) and hydroquinone (HQ). HTCTH was a more effective photoinitiator which had longer wavelength absorption in the UV-vis absorption spectra than the low molecular counterpart benzophenone (BP). It showed that both rate of polymerization (Rp) and final conversion (P) increased with increase of amine and HTCTH concentration in photopolymerization.
Catalytical oxidation of styrene by molecularly imprinted polymer with phenylacetic acid as template and hemin as co-monomer
Jun Wang , Zhi Yong Chen , Mei Ping Zhao , Yuan Zong Li
2007, 18(8): 981-984  doi: 10.1016/j.cclet.2007.06.009
[Abstract](145) [FullText HTML] [PDF 228KB](0)
This letter used the molecular imprinting technology to build up the microenvironment around co-monomer hemin to mimic the cytochrome P450 catalyzing the epoxidation of styrene. The results showed that the conversion rates of products were obviously enhanced by molecularly imprinted polymers, compared to free hemin solution, using three kinds of oxidants. The used axial ligand in polymers synthesis also improved the total conversion rates.
Determination of resveratrol in red wine by solid phase extraction-flow injection chemiluminescence method
Juan Juan Ren , Hai Yan Liu , Yu Hong Hao , Pin Gang He , Yu Zhi Fang
2007, 18(8): 985-988  doi: 10.1016/j.cclet.2007.06.013
[Abstract](144) [FullText HTML] [PDF 239KB](0)
A sensitive flow injection chemiluminescence method has been developed for the detection of resveratrol in red wine based on the fact that resveratrol can greatly enhance chemiluminescence reaction between KMnO4 and HCHO in sulfuric acid medium.Analytes were pre-concentrated on solid sorbents (C18 solid-phase extraction cartridges). Under the optimum conditions, the proposed method allows the measurement of resveratrol over the range of 1.32×10-8 to 1.32×10-5 mol/L with a detection limit of 3.30×10-9 mol/L, and the relative standard deviation for 1.32×10-5 mol/L resveratrol (n=11) is 3.8%. This method has been successfully applied for the determination of the resveratrol in red wine. Furthermore, the possible reaction mechanism was also discussed.
Multiwavelength spectrophotometric determination of acidity constants of 1-(2-thiazolylazo)-2-naphthol in methanol-water mixtures
Ali Niazi , Ateesa Yazdanipour , Majid Ramezani
2007, 18(8): 989-992  doi: 10.1016/j.cclet.2007.06.010
[Abstract](146) [FullText HTML] [PDF 428KB](1)
The acid-base properties of 1-(2-thiazolylazo)-2-naphthol (TAN) in mixtures of methanol-water at 25℃ and an ionic strength of 0.1 mol/L are studied by a multi-wavelength spectrophotometric method. The acidity constants of all related equilibria are estimated using the whole spectral fitting of the collected data to an established factor analysis model. DATAN program was used for determination of acidity constants. The corresponding pKa values in methanol-water mixtures were determined. There is a linear relationship between acidity constants and the mole fraction of methanol in the solvent mixtures.
Catalytic combustion of methane over nano ZrO2-supported copper-based catalysts
Fen Fen Qu , Wei Chu , Li Min Shi , Mu Hua Chen , Jin Yan Hu
2007, 18(8): 993-996  doi: 10.1016/j.cclet.2007.06.001
[Abstract](160) [FullText HTML] [PDF 506KB](0)
The nano ZrO2-supported copper-based catalysts for methane combustion were investigated by means of N2 adsorption, TEM, XRD, H2-TPR techniques and the test of methane oxidation. Two kinds of ZrO2 were used as support, one (ZrO2-1) was obtained from the commercial ZrO2 and the other (ZrO2-2) was issued from the thermal decomposition of zirconium nitrate. It was found that the CuO/ZrO2-2 catalyst was more active than CuO/ZrO2-1. N2 adsorption, H2-TPR and XRD measurements showed that larger surface area, better reduction property, presence of tetragonal ZrO2 and higher dispersion of active component for CuO/ZrO2-2 than that of CuO/ZrO2-1. These factors could be the dominating reasons for its higher activity for methane combustion.
High quality Sb-doped SnO2 electrodes with high oxygen evolution potential prepared by in situ hydrothermal synthesis method
Ai Sheng Huang , Guo Hua Zhao , Hong Xu Li
2007, 18(8): 997-1000  doi: 10.1016/j.cclet.2007.05.034
[Abstract](160) [FullText HTML] [PDF 1226KB](0)
High quality Sb-doped SnO2 electrode, with high oxygen evolution potential of 3.0 V, was successfully synthesized on the Ti substrates by in situ hydrothermal synthesis method.
Effect of hydrogen bonding and hydrophobic interaction on the formation of supramolecular hydrogels formed by L-phenylalanine derivative hydrogelator
Xin Jian Fu , Shu Qin Cao , Ning Xia Wang , Sheng Zu Zhang , Hong Wang , Ya Jiang Yang
2007, 18(8): 1001-1004  doi: 10.1016/j.cclet.2007.05.015
[Abstract](131) [FullText HTML] [PDF 365KB](0)
A new hydrogelator, pyridinium bromide salt of N-6-bromohexanoyl-L-phenylamino octadecane, was synthesized. Supramolecular hydrogels can be formed through the self-assembly of this hydrogelator in water. In this work, D2O was used instead of H2O as solvent for FT-IR measurement due to the fact that it is impossible to obtain useful FT-IR information on the hydrogen bonding in water. The investigation of FT-IR and steady-state fluorescence indicated that the driving forces for the self-assembly were mainly hydrogen bonding and hydrophobic interaction. Based on the data of XRD and molecular modeling, the possible mechanism of the formation of hydrogelator aggregates was proposed.
Antioxidant activity of polyaniline nanofibers
Jia Wang , Li Hua Zhu , Jing Li , He Qing Tang
2007, 18(8): 1005-1008  doi: 10.1016/j.cclet.2007.05.056
[Abstract](148) [FullText HTML] [PDF 1565KB](0)
Well-confined uniform polyaniline (PANT) nanofibers were synthesized by using photo-assisted chemical oxidative polymerization of aniline in the presence of different dopant acids, and the radical scavenging ability of the produced PANI nanofibers was determined by the DPPH assay. It was found that the antioxidant activity of PANI nanofibers was higher than conventional PANI, and increased with decreasing of averaged diameter of the nanofibers. The enhanced antioxidant activity was concerned with increased surface area of PANI nanofibers.
Assembling and releasing performance of supramolecular hydrogels formed from simple drug molecule as the hydrogelator
Yu Jiang Wang , Liang Yan , Li Ming Tang , Jian Yu
2007, 18(8): 1009-1012  doi: 10.1016/j.cclet.2007.05.008
[Abstract](199) [FullText HTML] [PDF 966KB](0)
A simple drug compound, 4-oxo-4-(2-pyridinylamino) butanoic acid (defined as AP), was able to gel water at 4 wt%concentration under various conditions. In the superstructure, AP molecules assembled into fibrous aggregates driving by hydrogen bonds and π-π stacking interaction. The gels with different backbone structures released drug molecules in different speeds.
Self-regeneration of activated carbon modified with palladium catalyst for electrochemical dechlorination
Yan Qing Cong , Zu Cheng Wu
2007, 18(8): 1013-1016  doi: 10.1016/j.cclet.2007.05.039
[Abstract](151) [FullText HTML] [PDF 1118KB](0)
Catalyst regeneration and the retention of high catalytic activity are still the critical issues in environmental application. A novel fluidized gas-liquid-solid electrochemical reactor was developed to simultaneously remove chlorinated pollutants and in situ regenerate the spent catalyst. Activated carbon modified with palladium catalyst (AC-Pd) was prepared for electrochemical dechlorination. For the 4-chlorophenol wastewater of initial concentration 200 mg L-1, the removal efficiency could nearly reach 100% in less than 30 min. Catalytic activity of AC-Pd catalyst was preserved effectively even in consecutive cycling run without special regeneration. *OH radicals, generated by electrochemical reaction, played a critical role in self-regeneration of AC-Pd. High catalytic activity of spent AC-Pd catalyst provided an attractive alternative in wastewater treatment.
In situ introduction of dispersed metallic Ag nanoparticles into the channels of mesoporous carbon CMK-3
Ai Bing Chen , Wei Ping Zhang , Yong Liu , Xiu Wen Han , Xin He Bao
2007, 18(8): 1017-1020  doi: 10.1016/j.cclet.2007.05.038
[Abstract](135) [FullText HTML] [PDF 798KB](0)
An in situ reduction method has been developed to fabricate metallic Ag nanoparticles inside the channels of mesoporous carbon CMK-3. This approach combines function of the CMK-3 surface by oxidation using HNO3 with the subsequent absorption of Ag+.The resultant nanocomposite materials were characterized by nitrogen adsorption, X-ray diffraction, Auger electron spectroscopy and transmission electron microscopy. Compared with the conventional impregnation method, our approach shows that Ag nanoparticles of 2-4 nm can be uniformly incorporated into CMK-3.
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