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2008 Volume 19 Issue 11
2008, 19(11): 1265-1267
doi: 10.1016/j.cclet.2008.09.022
Abstract:
An efficient synthetic route to muurolane type sesquiterpenes starting from (R)-carvone,employing allylic diazene rearrange-ment and the ring closing methesis (RCM) reaction as key steps,is described.The first asymmetric total synthesis of (-)-10α-hydroxy-4-muurolen-3-one B and (-)-10β-hydroxy-4-muurolen-3-one C was accomplished.Through the total synthesis,the absolute configurations of the natural products A,B and C were established.
An efficient synthetic route to muurolane type sesquiterpenes starting from (R)-carvone,employing allylic diazene rearrange-ment and the ring closing methesis (RCM) reaction as key steps,is described.The first asymmetric total synthesis of (-)-10α-hydroxy-4-muurolen-3-one B and (-)-10β-hydroxy-4-muurolen-3-one C was accomplished.Through the total synthesis,the absolute configurations of the natural products A,B and C were established.
2008, 19(11): 1268-1270
doi: 10.1016/j.cclet.2008.09.019
Abstract:
Four 4-monosubstituted pyrimidine pyridyl sulfonylureas were synthesized from pyridinesulfonamide and phenyl pyrimidyl-carbamate and screened for herbicidal activities.We also reported a convenient preparation process of phenyl pyrimidylcarbamates from pyrimidineamine and phenyl chloroformate.
Four 4-monosubstituted pyrimidine pyridyl sulfonylureas were synthesized from pyridinesulfonamide and phenyl pyrimidyl-carbamate and screened for herbicidal activities.We also reported a convenient preparation process of phenyl pyrimidylcarbamates from pyrimidineamine and phenyl chloroformate.
2008, 19(11): 1271-1273
doi: 10.1016/j.cclet.2008.09.024
Abstract:
Four new chiral 1,2,3,4-tetrahydroisoquinoline-derived β-amino alcohols were synthesized from L-DOPA in good yields.The structures of the target compounds were confirmed by 1H NMR,13C NMR and MS.
Four new chiral 1,2,3,4-tetrahydroisoquinoline-derived β-amino alcohols were synthesized from L-DOPA in good yields.The structures of the target compounds were confirmed by 1H NMR,13C NMR and MS.
2008, 19(11): 1274-1276
doi: 10.1016/j.cclet.2008.09.020
Abstract:
Wet carbon-based solid acid and potassium permanganate were used as new reagents for oxidation of alcohols to their corresponding aldehydes and ketones in heterogeneous mixtures.The experiments were done moderately at mild condition and high yields in suitable times were obtained.
Wet carbon-based solid acid and potassium permanganate were used as new reagents for oxidation of alcohols to their corresponding aldehydes and ketones in heterogeneous mixtures.The experiments were done moderately at mild condition and high yields in suitable times were obtained.
2008, 19(11): 1277-1280
doi: 10.1016/j.cclet.2008.09.010
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 K-10 supported cobalt(II) chloride.
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 K-10 supported cobalt(II) chloride.
2008, 19(11): 1281-1284
doi: 10.1016/j.cclet.2008.09.021
Abstract:
A new series of N1-acetylamino-(5-alkyl/aryl-1,3,4-thiadiazole-2-y1)-5-fluorouracil derivatives were designed and synthesized.These compounds have not been reported in literature,and their structure chemical were confirmed by IR,1H NMR and MS (HRMS).The results of antitumor inhibitory activity test showed that some compounds possess more potent antitumor inhibitory activity than 5-fluorouracil.
A new series of N1-acetylamino-(5-alkyl/aryl-1,3,4-thiadiazole-2-y1)-5-fluorouracil derivatives were designed and synthesized.These compounds have not been reported in literature,and their structure chemical were confirmed by IR,1H NMR and MS (HRMS).The results of antitumor inhibitory activity test showed that some compounds possess more potent antitumor inhibitory activity than 5-fluorouracil.
2008, 19(11): 1285-1289
doi: 10.1016/j.cclet.2008.06.056
Abstract:
Molecular wires with tetrathiafulvalene (TTF) as redox center were synthesized and characterized.UV-vis spectra and cyclic voltammetry showed these wires had good reversible redox behavior under ambient conditions and their HOMO energy levels (~-5.0 eV) matched well with the Fermi level of Au (~-5.1 eV).
Molecular wires with tetrathiafulvalene (TTF) as redox center were synthesized and characterized.UV-vis spectra and cyclic voltammetry showed these wires had good reversible redox behavior under ambient conditions and their HOMO energy levels (~-5.0 eV) matched well with the Fermi level of Au (~-5.1 eV).
2008, 19(11): 1290-1292
doi: 10.1016/j.cclet.2008.07.002
Abstract:
Protein tyrosine phosphatase 1B (PTP1B) plays an important role as a negative regulator and has been proved to be an effective target for the treatment of type 2 diabetes mellitus.Bis-(2,3-dibromo-4,5-dihydroxyphenyl)-methane 7 was first reported as a natural bromopbenol with significant inhibition against PTP1B which was isolated from red algae Rhodomela confervoides.Intrigued by its astonishing activity (IC50=2.4 μmol/L),compound 7 was synthesized with the overall yield of 24% and evaluated for its PTP1B inhibitory activity compared with natural compound.
Protein tyrosine phosphatase 1B (PTP1B) plays an important role as a negative regulator and has been proved to be an effective target for the treatment of type 2 diabetes mellitus.Bis-(2,3-dibromo-4,5-dihydroxyphenyl)-methane 7 was first reported as a natural bromopbenol with significant inhibition against PTP1B which was isolated from red algae Rhodomela confervoides.Intrigued by its astonishing activity (IC50=2.4 μmol/L),compound 7 was synthesized with the overall yield of 24% and evaluated for its PTP1B inhibitory activity compared with natural compound.
2008, 19(11): 1293-1296
doi: 10.1016/j.cclet.2008.07.014
Abstract:
A novel fluorinated polyurethane (FPU) with fluorine-containing pendent groups was prepared by using fluorinated polyether glycol (PTMG-g-HFP) as a soft segment,1,6-hexamethylene diisocyanate (HDI) or toluene diisocyanate (TDI) as a hard segment and 1,4-butanodiol (BDO) as a chain extender.FTIR,1H NMR,13C NMR and GPC were used to characterize the structure of the fluorinated polyurethane.Thermal stabilities of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were studied by TGA.XPS analysis at two different sampling depths for the fluorinated polyurethane was used to investigate the surface compositions of FPU.The results showed the fluorine enrichment on the surface of FPU.
A novel fluorinated polyurethane (FPU) with fluorine-containing pendent groups was prepared by using fluorinated polyether glycol (PTMG-g-HFP) as a soft segment,1,6-hexamethylene diisocyanate (HDI) or toluene diisocyanate (TDI) as a hard segment and 1,4-butanodiol (BDO) as a chain extender.FTIR,1H NMR,13C NMR and GPC were used to characterize the structure of the fluorinated polyurethane.Thermal stabilities of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were studied by TGA.XPS analysis at two different sampling depths for the fluorinated polyurethane was used to investigate the surface compositions of FPU.The results showed the fluorine enrichment on the surface of FPU.
2008, 19(11): 1297-1300
doi: 10.1016/j.cclet.2008.07.020
Abstract:
(+)-cis-(1S,2R)-Epoxypropylphosphonic acid,the enantiomer of fosfomycin,which is the industrial side-product in the preparation of the antibiotic fosfomycin,was converted into (-)fosfomycin by a seven-step procedure.The esterification of the dihydroxyphosphonic intermediate was the key step.The title compound was obtained in good yield and its optical purity was up to the medicine quality standard of Chinese Pharmacopoeia.
(+)-cis-(1S,2R)-Epoxypropylphosphonic acid,the enantiomer of fosfomycin,which is the industrial side-product in the preparation of the antibiotic fosfomycin,was converted into (-)fosfomycin by a seven-step procedure.The esterification of the dihydroxyphosphonic intermediate was the key step.The title compound was obtained in good yield and its optical purity was up to the medicine quality standard of Chinese Pharmacopoeia.
2008, 19(11): 1301-1304
doi: 10.1016/j.cclet.2008.07.019
Abstract:
A simple and environmentally friendly method is described for the efficient conversion of alkyl halide to alkyl thiocyanate using tetrabutylammonium bromide (TBAB) as a phase transfer catalyst.The reactions occur in water and furnish the corresponding alkyl thiocyanate in high yields.No evidence for the formation of isothiocyanates as by-product of the reaction was observed and the products were obtained in pure form without further purification.
A simple and environmentally friendly method is described for the efficient conversion of alkyl halide to alkyl thiocyanate using tetrabutylammonium bromide (TBAB) as a phase transfer catalyst.The reactions occur in water and furnish the corresponding alkyl thiocyanate in high yields.No evidence for the formation of isothiocyanates as by-product of the reaction was observed and the products were obtained in pure form without further purification.
2008, 19(11): 1305-1308
doi: 10.1016/j.cclet.2008.07.017
Abstract:
Rapid and highly efficient synthesis of some 1-aroy1-3,5-dimethylpyrazoles is achieved by the cyclocondensation of corresponding aroyl hydrazides with 2,4-pentanedione in the absence of solvent and catalyst,under microwave irradiation.The reaction proceeds rapidly and is completed within 40-70 s giving a series of 1-aroy1-3,5-dimethylpyrazoles derivatives in high yields.All of the compounds have been characterized by FTIR,1H NMR,and mass spectroscopy.
Rapid and highly efficient synthesis of some 1-aroy1-3,5-dimethylpyrazoles is achieved by the cyclocondensation of corresponding aroyl hydrazides with 2,4-pentanedione in the absence of solvent and catalyst,under microwave irradiation.The reaction proceeds rapidly and is completed within 40-70 s giving a series of 1-aroy1-3,5-dimethylpyrazoles derivatives in high yields.All of the compounds have been characterized by FTIR,1H NMR,and mass spectroscopy.
2008, 19(11): 1309-1311
doi: 10.1016/j.cclet.2008.09.016
Abstract:
lsotetronic acids are of great agricultural and pharmacological relevance and occur in a number of natural products.A convenient synthetic pathway to β-aryl substituted isotetronic acid derivatives was developed via Suzuki cross-coupling of the corresponding β-bromo substituted isotetronic acid derivatives with arylboronic acids under palladium acetate catalysis.Good to excellent yields have been achieved.
lsotetronic acids are of great agricultural and pharmacological relevance and occur in a number of natural products.A convenient synthetic pathway to β-aryl substituted isotetronic acid derivatives was developed via Suzuki cross-coupling of the corresponding β-bromo substituted isotetronic acid derivatives with arylboronic acids under palladium acetate catalysis.Good to excellent yields have been achieved.
2008, 19(11): 1312-1314
doi: 10.1016/j.cclet.2008.09.026
Abstract:
A novel reaction-induced method with the aid of solvent for porous thermosetting epoxy was first carried out.Investigations of pore structure using scanning electron microscope (SEM) showed that porous epoxy networks with average pore size ranging from 3 to 20 μm were obtained.The pore structure generated by this method can be tailored by changing the solvent content.
A novel reaction-induced method with the aid of solvent for porous thermosetting epoxy was first carried out.Investigations of pore structure using scanning electron microscope (SEM) showed that porous epoxy networks with average pore size ranging from 3 to 20 μm were obtained.The pore structure generated by this method can be tailored by changing the solvent content.
2008, 19(11): 1315-1318
doi: 10.1016/j.cclet.2008.09.011
Abstract:
Two flavonoid triglycosides,kaempferol 3-O-{β-D-glucopyranosyl-(1→2)-[a-L-rhamnopyranosyl-(1→6)]-β-D-glucopyra-noside} (1) and kaempferol 3-O-{β-D-xylopyranosyl-(1→2)-[a-L-rhamnopyranosyl-(1→6)]-[β-D-glucopyranoside} (2),were isolated from the seed of Camellia oleifera Abel.The absolute configuration of compound 1 was established on the basis of its X-ray analysis.Their cytotoxic activities and anti-HIV-RT activities were evaluated.
Two flavonoid triglycosides,kaempferol 3-O-{β-D-glucopyranosyl-(1→2)-[a-L-rhamnopyranosyl-(1→6)]-β-D-glucopyra-noside} (1) and kaempferol 3-O-{β-D-xylopyranosyl-(1→2)-[a-L-rhamnopyranosyl-(1→6)]-[β-D-glucopyranoside} (2),were isolated from the seed of Camellia oleifera Abel.The absolute configuration of compound 1 was established on the basis of its X-ray analysis.Their cytotoxic activities and anti-HIV-RT activities were evaluated.
2008, 19(11): 1319-1322
doi: 10.1016/j.cclet.2008.09.013
Abstract:
Three new compounds,including one chloro-furoeremophilanoid (1),one eremophiladiolide (2),a rare dimer of nor-furoeremophilanoid,ligulatrovine A (3),and a known furoeremophilanolide (4),were isolated from Ligularia atroviolacea.The structures of compounds 1-4 were elucidated by spectroscopic methods including ID and 2D NMR experiments as well as X-ray diffraction study.
Three new compounds,including one chloro-furoeremophilanoid (1),one eremophiladiolide (2),a rare dimer of nor-furoeremophilanoid,ligulatrovine A (3),and a known furoeremophilanolide (4),were isolated from Ligularia atroviolacea.The structures of compounds 1-4 were elucidated by spectroscopic methods including ID and 2D NMR experiments as well as X-ray diffraction study.
2008, 19(11): 1323-1326
doi: 10.1016/j.cclet.2008.09.006
Abstract:
Two new tetralone derivatives named xylariol A (1) and B (2) were isolated from the EtOAc extract of the culture broth of Xylaria hypoxylon AT-028 (Xylariaceae),and their structures were elucidated by MS,IR,ID-and 2D-NMR spectra,and by X-ray diffraction analysis. 1 and 2 showed moderate cytotoxic activities against Hep G2 cells in the in vitro cytotoxic assay with ICso values of 22.3 and 21.2 μg/mL,respectively.
Two new tetralone derivatives named xylariol A (1) and B (2) were isolated from the EtOAc extract of the culture broth of Xylaria hypoxylon AT-028 (Xylariaceae),and their structures were elucidated by MS,IR,ID-and 2D-NMR spectra,and by X-ray diffraction analysis. 1 and 2 showed moderate cytotoxic activities against Hep G2 cells in the in vitro cytotoxic assay with ICso values of 22.3 and 21.2 μg/mL,respectively.
2008, 19(11): 1327-1329
doi: 10.1016/j.cclet.2008.09.012
Abstract:
Two new benzofuran lignan glycosides,gelsemiunoside A and B,were isolated from the whole plant of Gelsemium elegans Benth.Their structures were elucidated on the basis of spectroscopic evidence.Furthermore,gelsemiunoside A and B were shown a potent cytotoxic activity by suppressing the proliferation of A375-S2 cells.
Two new benzofuran lignan glycosides,gelsemiunoside A and B,were isolated from the whole plant of Gelsemium elegans Benth.Their structures were elucidated on the basis of spectroscopic evidence.Furthermore,gelsemiunoside A and B were shown a potent cytotoxic activity by suppressing the proliferation of A375-S2 cells.
2008, 19(11): 1330-1332
doi: 10.1016/j.cclet.2008.07.024
Abstract:
This paper reports a new route for the preparation of layered alpha-zirconium phosphate (α-ZrP)-supponed metalloporphyrin MnTMPyp.MnTMPyP was intercalated into α-ZrP using α-ZrP·BA (i.e.pre-intercalated buitylamine was arranged by a monolayer mode in α-ZrP) as a starting material.The catalytic activity of the supported material for homovanillic acid (HVA) oxidation was investigated.The results showed a promising layered material-supported catalyst in catalytic system.
This paper reports a new route for the preparation of layered alpha-zirconium phosphate (α-ZrP)-supponed metalloporphyrin MnTMPyp.MnTMPyP was intercalated into α-ZrP using α-ZrP·BA (i.e.pre-intercalated buitylamine was arranged by a monolayer mode in α-ZrP) as a starting material.The catalytic activity of the supported material for homovanillic acid (HVA) oxidation was investigated.The results showed a promising layered material-supported catalyst in catalytic system.
Simultaneous laser-induced fluorescence and contactless-conductivity detection for microfluidic chip
2008, 19(11): 1333-1336
doi: 10.1016/j.cclet.2008.06.057
Abstract:
A combined detection system involving simultaneous LIF and contactless-conductometric measurements at the same place of the microfluidic chip was described.The LIF measurement was designed according to the confocal principle and a moveable contactless-conductivity detector was used in C4D.Both measurements were mutually independent and advantageous in analyses of mixtures.Various experimental parameters affecting the response were examined and optimized.The performances were demonstrated by simultaneous detection of Rhodamine B.And the results showed that the combined detection system could be used sensitively and reliably.
A combined detection system involving simultaneous LIF and contactless-conductometric measurements at the same place of the microfluidic chip was described.The LIF measurement was designed according to the confocal principle and a moveable contactless-conductivity detector was used in C4D.Both measurements were mutually independent and advantageous in analyses of mixtures.Various experimental parameters affecting the response were examined and optimized.The performances were demonstrated by simultaneous detection of Rhodamine B.And the results showed that the combined detection system could be used sensitively and reliably.
2008, 19(11): 1337-1340
doi: 10.1016/j.cclet.2008.07.013
Abstract:
The electrochemical behaviour and electrode reaction mechanism of ziram (zinc-dimethyl dithiocarbamate) on a hanging mercury drop electrode were investigated in Britton-Robinson (B-R) buffer by using cyclic and square wave voltammetry (SWV).Based on these studies a voltammetric method for determination of ziram was developed and applied to determine the ziram in synthetic and spiked vegetable samples,satisfactory results were obtained in both eases.
The electrochemical behaviour and electrode reaction mechanism of ziram (zinc-dimethyl dithiocarbamate) on a hanging mercury drop electrode were investigated in Britton-Robinson (B-R) buffer by using cyclic and square wave voltammetry (SWV).Based on these studies a voltammetric method for determination of ziram was developed and applied to determine the ziram in synthetic and spiked vegetable samples,satisfactory results were obtained in both eases.
2008, 19(11): 1341-1344
doi: 10.1016/j.cclet.2008.09.004
Abstract:
The interaction of the novel tetra-carboxylphenyl calix[4]arene (TCPC) with the bovine heart cytochrome c (Cc) was first investigated by fluorescence spectroscopy and molecular modeling methods.The formation of a stable 1:1 complex was monitored by fluorescence titration,and its binding constant is 1.916×107 L mol-1. Molecular modeling reveals the recognition mechanism of TCPC to the Cc surface,that is,the electrostatic interaction drives TCPC to the Cc surface,and the van der Waals interaction orientates TCPC parallel to the cleft of Cc.
The interaction of the novel tetra-carboxylphenyl calix[4]arene (TCPC) with the bovine heart cytochrome c (Cc) was first investigated by fluorescence spectroscopy and molecular modeling methods.The formation of a stable 1:1 complex was monitored by fluorescence titration,and its binding constant is 1.916×107 L mol-1. Molecular modeling reveals the recognition mechanism of TCPC to the Cc surface,that is,the electrostatic interaction drives TCPC to the Cc surface,and the van der Waals interaction orientates TCPC parallel to the cleft of Cc.
2008, 19(11): 1345-1348
doi: 10.1016/j.cclet.2008.07.018
Abstract:
A new chromatographic purification of single-walled carbon nanotubes using high-speed countercurrent chromatography is reported.The purification was accomplished on the basis of experiment that dispersed the single-walled carbon nanotubes with sodium dodecyl sulfate,and the result mixture was separated using the two phase system composed of n-butanol/water=1/1 (v/v).The sizes of SWNTs separated were observed by scanning electron microscopy.The results demonstrated that the high-speed countercurrent chromatography possessed a good efficency for purification of single-walled carbon nanotubes.
A new chromatographic purification of single-walled carbon nanotubes using high-speed countercurrent chromatography is reported.The purification was accomplished on the basis of experiment that dispersed the single-walled carbon nanotubes with sodium dodecyl sulfate,and the result mixture was separated using the two phase system composed of n-butanol/water=1/1 (v/v).The sizes of SWNTs separated were observed by scanning electron microscopy.The results demonstrated that the high-speed countercurrent chromatography possessed a good efficency for purification of single-walled carbon nanotubes.
2008, 19(11): 1349-1352
doi: 10.1016/j.cclet.2008.09.002
Abstract:
Two phenylethanoid glycosides (PhGs) were isolated and purified from the aerial parts of Plantago asiatica for the first time by high performance centrifugal partition chromatography (HPCPC) using ethyl acetate-n-butanol-ethanol-water (0.5:0.5:0.1:1,v/v/v/v). A total of 45.6 mg of compound 1 and 293.8 mg of compound 2 were purified from 1341 mg of the n-butanol extract of P.asiatica.The structures of the two PhGs were tentatively identified as plantamajoside and acteoside or isoacteoside by electrospray ionization multi stage tandem mass spectrometry (ESI-MSn) in the negative ion mode.
Two phenylethanoid glycosides (PhGs) were isolated and purified from the aerial parts of Plantago asiatica for the first time by high performance centrifugal partition chromatography (HPCPC) using ethyl acetate-n-butanol-ethanol-water (0.5:0.5:0.1:1,v/v/v/v). A total of 45.6 mg of compound 1 and 293.8 mg of compound 2 were purified from 1341 mg of the n-butanol extract of P.asiatica.The structures of the two PhGs were tentatively identified as plantamajoside and acteoside or isoacteoside by electrospray ionization multi stage tandem mass spectrometry (ESI-MSn) in the negative ion mode.
2008, 19(11): 1353-1357
doi: 10.1016/j.cclet.2008.09.005
Abstract:
A new benzoimidazole-naphthalimide derivative 4 was synthesized and its photophysical properties were studied.This compound showed highly selectively and sensitive colorimetric and ratiometric sensing ability for fluoride anion.
A new benzoimidazole-naphthalimide derivative 4 was synthesized and its photophysical properties were studied.This compound showed highly selectively and sensitive colorimetric and ratiometric sensing ability for fluoride anion.
2008, 19(11): 1358-1362
doi: 10.1016/j.cclet.2008.06.045
Abstract:
The kinetic study of in-situ copolymerization of aniline with o-and p-methylaniline by ammonium persulfate (APS) has been carried out.UV-vis spectroscopic method was used to investigate the course of copolymerization.Structural characterization was studied by FT-IR spectral analysis.The electronic spectra of the copolymers poly(aniline-co-p-toluidine) and poly(aniline-co-o-tolnidine) show blue shift.The shift has been observed in the bands corresponding to π→π* transition as well as in the exciton transition.The increase in absorbance recorded during the reaction for different concentration of aniline,o-and p-toluidine at various intervals of time of polymerization reaction indicates a growth in the polymer formation.The resulting first-order rateconstant was used to calculate the rate of copolymer formation using the rate equation-d[A]/dt=kcn.
The kinetic study of in-situ copolymerization of aniline with o-and p-methylaniline by ammonium persulfate (APS) has been carried out.UV-vis spectroscopic method was used to investigate the course of copolymerization.Structural characterization was studied by FT-IR spectral analysis.The electronic spectra of the copolymers poly(aniline-co-p-toluidine) and poly(aniline-co-o-tolnidine) show blue shift.The shift has been observed in the bands corresponding to π→π* transition as well as in the exciton transition.The increase in absorbance recorded during the reaction for different concentration of aniline,o-and p-toluidine at various intervals of time of polymerization reaction indicates a growth in the polymer formation.The resulting first-order rateconstant was used to calculate the rate of copolymer formation using the rate equation-d[A]/dt=kcn.
2008, 19(11): 1363-1366
doi: 10.1016/j.cclet.2008.07.012
Abstract:
A short-chain triblock copolymer EO9-DMS7-EO9 was synthesized by coupling reaction of allyl-terminated poly(ethylene oxide) and Si-H-terminated poly(dimethylsiloxane).The structure and purity of synthesized copolymer was carefully character-ized.Self-assembly behavior of EO9-DMS7-EO9 triblock copolymer in water was investigated.And it was found that along with the increase of copolymer concentration,morphology of self-assembled aggregates transits from sphere to rod.A plausible under-standing of the morphology transition for the investigated triblock copolymer was proposed.
A short-chain triblock copolymer EO9-DMS7-EO9 was synthesized by coupling reaction of allyl-terminated poly(ethylene oxide) and Si-H-terminated poly(dimethylsiloxane).The structure and purity of synthesized copolymer was carefully character-ized.Self-assembly behavior of EO9-DMS7-EO9 triblock copolymer in water was investigated.And it was found that along with the increase of copolymer concentration,morphology of self-assembled aggregates transits from sphere to rod.A plausible under-standing of the morphology transition for the investigated triblock copolymer was proposed.
2008, 19(11): 1367-1370
doi: 10.1016/j.cclet.2008.06.040
Abstract:
Electroless Ni-P/nano-CeO2 composite coating was prepared in acidic condition,and its microstructure and corrosive property were compared with its CeO2-free counterpart.Scanning electronic microscopy (SEM) and X-ray diffraction (XRD) spectrometer were used to examine surface morphology and structure of the as-plated coating.Differential scanning calorimeter (DSC) and transmission electronic microscopy (TEM) were used to study the coating's phase change at high temperature.The coating's corrosive behavior in 3%NaCI+5%H2SO4 solution was also investigated.The results showed that Ni-P coating had partial amorphous structure mixed with nano-crystals,while the Ni-P/CeO2 coating had perfect amorphous structure.In high-temperature condition,Ni3P precipitation and Ni crystallization took place in both coatings but at different temperatures,while the Ni-P/CeO2 coating had sintered phase of NiCe2O4 spinels.The anti-corrosion property was better in the CeO2-containing coating,and this was due to its less liability to undergo local-cell corrosion than its CeO2-free counterpart.Ni-P/CeO2 coating's pure amorphous structure was the result of Ni's hindered crystal-typed deposition and P's promoted deposition.
Electroless Ni-P/nano-CeO2 composite coating was prepared in acidic condition,and its microstructure and corrosive property were compared with its CeO2-free counterpart.Scanning electronic microscopy (SEM) and X-ray diffraction (XRD) spectrometer were used to examine surface morphology and structure of the as-plated coating.Differential scanning calorimeter (DSC) and transmission electronic microscopy (TEM) were used to study the coating's phase change at high temperature.The coating's corrosive behavior in 3%NaCI+5%H2SO4 solution was also investigated.The results showed that Ni-P coating had partial amorphous structure mixed with nano-crystals,while the Ni-P/CeO2 coating had perfect amorphous structure.In high-temperature condition,Ni3P precipitation and Ni crystallization took place in both coatings but at different temperatures,while the Ni-P/CeO2 coating had sintered phase of NiCe2O4 spinels.The anti-corrosion property was better in the CeO2-containing coating,and this was due to its less liability to undergo local-cell corrosion than its CeO2-free counterpart.Ni-P/CeO2 coating's pure amorphous structure was the result of Ni's hindered crystal-typed deposition and P's promoted deposition.
2008, 19(11): 1371-1374
doi: 10.1016/j.cclet.2008.09.008
Abstract:
A novel anodic oxidization equipment was designed to fabricate a large number of porous anodic alumina (PAA) templates in one time.This approach improved the efficiency of the preparation of the PAA templates remarkably in a normal lab and is expected to be used for the large-scale production in the future.
A novel anodic oxidization equipment was designed to fabricate a large number of porous anodic alumina (PAA) templates in one time.This approach improved the efficiency of the preparation of the PAA templates remarkably in a normal lab and is expected to be used for the large-scale production in the future.
2008, 19(11): 1375-1378
doi: 10.1016/j.cclet.2008.09.001
Abstract:
The explosion characteristics of chlorine dioxide gas have been studied for the first time in a cylindrical exploder with a shell capacity of 201.The experimental results have indicated that the lower concentration limit for the explosive decomposition of chlorine dioxide gas is 9.5% ([ClO2]/[airl]),whereas there is no corresponding upper concentration limit.The maximum pressure of explosion relative to the initial pressure was measured as 0.024 MPa at 10% ClO2 and 0.641 MPa at 90% ClO2.The induction time (the time from the moment of sparking to explosion) at 10% ClO2 was 2195 ms,but at 90% ClO2 the induction time was just 8 ms.The explosion reaction mechanism of ClO2 is of a degenerate chain-branching type involving the formation of a stable intermediate (Cl2O3),from which the chain branching occurs.
The explosion characteristics of chlorine dioxide gas have been studied for the first time in a cylindrical exploder with a shell capacity of 201.The experimental results have indicated that the lower concentration limit for the explosive decomposition of chlorine dioxide gas is 9.5% ([ClO2]/[airl]),whereas there is no corresponding upper concentration limit.The maximum pressure of explosion relative to the initial pressure was measured as 0.024 MPa at 10% ClO2 and 0.641 MPa at 90% ClO2.The induction time (the time from the moment of sparking to explosion) at 10% ClO2 was 2195 ms,but at 90% ClO2 the induction time was just 8 ms.The explosion reaction mechanism of ClO2 is of a degenerate chain-branching type involving the formation of a stable intermediate (Cl2O3),from which the chain branching occurs.
2008, 19(11): 1379-1382
doi: 10.1016/j.cclet.2008.07.007
Abstract:
A realistic dynamics simulation study is reported for the trans-cis photoisomerization of azobenzene triggered by the n→π* excitation and the results show that the formation of cis isomer follows the rotational motion around the N=N bond.The simulation find that the CNN bond angle bending vibrations also play a significant role in the vibronic coupling between the HOMO and LUMO,which essentially leads a nonadiabatic transition of the molecule to the electronic ground state.
A realistic dynamics simulation study is reported for the trans-cis photoisomerization of azobenzene triggered by the n→π* excitation and the results show that the formation of cis isomer follows the rotational motion around the N=N bond.The simulation find that the CNN bond angle bending vibrations also play a significant role in the vibronic coupling between the HOMO and LUMO,which essentially leads a nonadiabatic transition of the molecule to the electronic ground state.
2008, 19(11): 1383-1386
doi: 10.1016/j.cclet.2008.07.025
Abstract:
Density functional theoretical calculations have been made on the electronic structure of (CH)n(BCO)6-n(n=0-6) at B3LYP/6-311+G(d) level.The nuclear-independent chemical shifts (NICS) values calculated using the gauge-including atomic orbitals (GIAO) method were used to assess on the aromaticities of these molecules.The results shows that (CH)n(BCO)6-n(n=0-6)species are aromatic.
Density functional theoretical calculations have been made on the electronic structure of (CH)n(BCO)6-n(n=0-6) at B3LYP/6-311+G(d) level.The nuclear-independent chemical shifts (NICS) values calculated using the gauge-including atomic orbitals (GIAO) method were used to assess on the aromaticities of these molecules.The results shows that (CH)n(BCO)6-n(n=0-6)species are aromatic.
2008, 19(11): 1387-1390
doi: 10.1016/j.cclet.2008.07.010
Abstract:
The catalytic activity of Cu-ZSM-5 in trichloroethylene (TCE) combustion increases with the increasing skeletal Cu amount and however decreases with the increase of surface amorphous CuO,which is detected by infrared spectroscopy (IR) and diffuse reflectance ultraviolet-visible spectroscopy (DRS-UV-vis),therefore the skeletal Cu species are concluded to be the active sites for the TCE combustion.
The catalytic activity of Cu-ZSM-5 in trichloroethylene (TCE) combustion increases with the increasing skeletal Cu amount and however decreases with the increase of surface amorphous CuO,which is detected by infrared spectroscopy (IR) and diffuse reflectance ultraviolet-visible spectroscopy (DRS-UV-vis),therefore the skeletal Cu species are concluded to be the active sites for the TCE combustion.
