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2009 Volume 20 Issue 10
2009, 20(10): 235-1240
doi: 10.1016/j.cclet.2009.05.004
Abstract:
Under visible light illumination, 2,3-diaminophenazine (DAPN) was generated from the oxidation of o-phenylenediamine (OPDA) in Fe3+/H 2O2 solution.Hydroxyl radical (·OH) produced in this system was determined by directly measuring the concentration of DAPN.In comparison with the traditional methods, the determination is more accurate and simple.
Under visible light illumination, 2,3-diaminophenazine (DAPN) was generated from the oxidation of o-phenylenediamine (OPDA) in Fe3+/H 2O2 solution.Hydroxyl radical (·OH) produced in this system was determined by directly measuring the concentration of DAPN.In comparison with the traditional methods, the determination is more accurate and simple.
2009, 20(10): 1124-1126
doi: 10.1016/j.cclet.2009.05.026
Abstract:
A new sesquiterpene trilactone, named bilobanol (1), along with four known terpene trilactones (ginkgolide A, B, C and bilobalide) were isolated from the roots of Ginkgo biloba collected in Jiangsu Province, China.The structure elucidation was accomplished by 1D and 2D NMR methods, HR-ESI-MS, and CD spectrum.
A new sesquiterpene trilactone, named bilobanol (1), along with four known terpene trilactones (ginkgolide A, B, C and bilobalide) were isolated from the roots of Ginkgo biloba collected in Jiangsu Province, China.The structure elucidation was accomplished by 1D and 2D NMR methods, HR-ESI-MS, and CD spectrum.
2009, 20(10): 1141-1144
doi: 10.1016/j.cclet.2009.04.001
Abstract:
28-Carboxymethoxy lupane tritepenoids 3 and 4 were synthesized by alkylation of betulin with the THP protected 2-hydroxyethyl iodide followed by oxidation and reduction.Direct reaction of betulin (5) or betulone (10) with ethyl bromoacetate led to 28-O-acylation, instead of 28-O-alkylation.The targeted compounds 3 and 4 were not cytotoxic at the highest concentrationtested (75 mmol/L), suggesting that elongation of the chain length at the 28-position in both betulinic acid (1) and betulonic acid (2)was detrimental to the cytotoxicity.The acylation products 28-O-bromoacetates (8a, 8b and 11) and 28-O-methoxyacetate 13exhibited cytotoxicity against several cancer cell lines tested.
28-Carboxymethoxy lupane tritepenoids 3 and 4 were synthesized by alkylation of betulin with the THP protected 2-hydroxyethyl iodide followed by oxidation and reduction.Direct reaction of betulin (5) or betulone (10) with ethyl bromoacetate led to 28-O-acylation, instead of 28-O-alkylation.The targeted compounds 3 and 4 were not cytotoxic at the highest concentrationtested (75 mmol/L), suggesting that elongation of the chain length at the 28-position in both betulinic acid (1) and betulonic acid (2)was detrimental to the cytotoxicity.The acylation products 28-O-bromoacetates (8a, 8b and 11) and 28-O-methoxyacetate 13exhibited cytotoxicity against several cancer cell lines tested.
2009, 20(10): 1145-1149
doi: 10.1016/j.cclet.2009.04.032
Abstract:
The efficient cycloaddition reactions were carried out to afford the novel 3,5-disubstituted-dihydroisoxazoles from methyl undec-10-enoate and isoxazoles, triazole and tetrazolo-triazole from methyl undec-10-ynoate.The reactions occurred under relatively mild conditions and afforded the desired products in good yields.
The efficient cycloaddition reactions were carried out to afford the novel 3,5-disubstituted-dihydroisoxazoles from methyl undec-10-enoate and isoxazoles, triazole and tetrazolo-triazole from methyl undec-10-ynoate.The reactions occurred under relatively mild conditions and afforded the desired products in good yields.
2009, 20(10): 1150-1152
doi: 10.1016/j.cclet.2009.05.033
Abstract:
A practical protocol to obtain 1,1'-binaphthyl-2,2'-diamine was developed from 2-naphthol and 2-naphthylhydrazine under mild conditions:solvent-free, 125-130℃, atmospheric pressure.The convenient procedure makes the process amenable for large-scale synthesis of the versatile compound.
A practical protocol to obtain 1,1'-binaphthyl-2,2'-diamine was developed from 2-naphthol and 2-naphthylhydrazine under mild conditions:solvent-free, 125-130℃, atmospheric pressure.The convenient procedure makes the process amenable for large-scale synthesis of the versatile compound.
2009, 20(10): 1153-1156
doi: 10.1016/j.cclet.2009.06.001
Abstract:
Six new optically active poly(amide-imide)s (5a-f) were synthesized through the direct polycondensation reaction of N,N'-(4,4'-diphthaloyl)-bis-L-leucine (3) with six hydantoin derivatives (4a-f).Triphenyl phosphite (TPP)/pyridine in the presence of calcium chloride (CaCl 2) and N-methyl-2-pyrrolidone (NMP) were successfully applied for direct polycondensation.The polycondensation reactions produce a series of new poly(amide-imide)s (5a-f) in high yields, and inherent viscosity between 0.42 and 0.55 dL/g.The resulting poly(amide-imide)s (5a-f) were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis (TGA and DTG), solubility test and FT-IR spectroscopy.
Six new optically active poly(amide-imide)s (5a-f) were synthesized through the direct polycondensation reaction of N,N'-(4,4'-diphthaloyl)-bis-L-leucine (3) with six hydantoin derivatives (4a-f).Triphenyl phosphite (TPP)/pyridine in the presence of calcium chloride (CaCl 2) and N-methyl-2-pyrrolidone (NMP) were successfully applied for direct polycondensation.The polycondensation reactions produce a series of new poly(amide-imide)s (5a-f) in high yields, and inherent viscosity between 0.42 and 0.55 dL/g.The resulting poly(amide-imide)s (5a-f) were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis (TGA and DTG), solubility test and FT-IR spectroscopy.
2009, 20(10): 1157-1160
doi: 10.1016/j.cclet.2009.04.028
Abstract:
A new debenzylation of benzyl esters by silica-supported sodium hydrogen sulfate is described.The debenzylation could be achieved selectively and efficiently in good to excellent yields without affecting sensitive functional groups such as nitro,unsaturated bonds, and ethyl ester.
A new debenzylation of benzyl esters by silica-supported sodium hydrogen sulfate is described.The debenzylation could be achieved selectively and efficiently in good to excellent yields without affecting sensitive functional groups such as nitro,unsaturated bonds, and ethyl ester.
2009, 20(10): 1161-1165
doi: 10.1016/j.cclet.2009.04.014
Abstract:
Novel pyrimidine nucleoside-3,5-dicyanopyridine hybrids (4) or pyridine attached acylureas (5) were selectively and efficiently prepared from the reaction of 2'-deoxyuridin-5-yl-methylene malononitrile (1), malononitrile (2) and thiophenol (3) or from an unexpected uracil ring-opening and pyridine ring-forming sequence via the reaction of 1 and 3.It is the first time such a sequence has ever been reported.
Novel pyrimidine nucleoside-3,5-dicyanopyridine hybrids (4) or pyridine attached acylureas (5) were selectively and efficiently prepared from the reaction of 2'-deoxyuridin-5-yl-methylene malononitrile (1), malononitrile (2) and thiophenol (3) or from an unexpected uracil ring-opening and pyridine ring-forming sequence via the reaction of 1 and 3.It is the first time such a sequence has ever been reported.
2009, 20(10): 1166-1168
doi: 10.1016/j.cclet.2009.04.031
Abstract:
Calix[4]-crown-5-sulfonyl cyclothiourea derivatives 6 and 7 were synthesized from calix[4]-crown-5-monosulfonylethylenediamine derivatives 4 and 5 and carbon disulfide through nucleophilic addition and subsequent cyclization of intramolecule at room temperature in aqueous solution.The advantages of the novel protocol are the mild reaction condition, free organic solvent, simple final treatment, easy isolation of products and excellent yields.
Calix[4]-crown-5-sulfonyl cyclothiourea derivatives 6 and 7 were synthesized from calix[4]-crown-5-monosulfonylethylenediamine derivatives 4 and 5 and carbon disulfide through nucleophilic addition and subsequent cyclization of intramolecule at room temperature in aqueous solution.The advantages of the novel protocol are the mild reaction condition, free organic solvent, simple final treatment, easy isolation of products and excellent yields.
2009, 20(10): 1170-1174
doi: 10.1016/j.cclet.2009.06.004
Abstract:
A catalytic method was developed to synthesize substituted phenols from the corresponding aryl bromides and chlorides under mild conditions (yields=34-92%).4-Methoxylbenzyl alcohol was used as water surrogate and CuI/3,4,7,8-tetramethyl-1,10-phenanthroline was used as catalyst to achieve the C-O cross-coupling.
A catalytic method was developed to synthesize substituted phenols from the corresponding aryl bromides and chlorides under mild conditions (yields=34-92%).4-Methoxylbenzyl alcohol was used as water surrogate and CuI/3,4,7,8-tetramethyl-1,10-phenanthroline was used as catalyst to achieve the C-O cross-coupling.
2009, 20(10): 1175-1178
doi: 10.1016/j.cclet.2009.05.019
Abstract:
A convenient and facile one-pot synthesis of stable phosphorus ylides and 1,4-diionic organophosphorus compounds is reported by the reaction of triphenylphosphine, dialkylacetylenedicarboxylates and N-H, C-H or S-H acids in the presence of polyethyleneglycol (PEG), b-cyclodextrin (β-CD), glycerine (Gly) or ethyleneglycol (EG) in water.This methodology is of interest due to the use of water as a solvent, thus minimizing the cost operational hazards, and environmental pollution.
A convenient and facile one-pot synthesis of stable phosphorus ylides and 1,4-diionic organophosphorus compounds is reported by the reaction of triphenylphosphine, dialkylacetylenedicarboxylates and N-H, C-H or S-H acids in the presence of polyethyleneglycol (PEG), b-cyclodextrin (β-CD), glycerine (Gly) or ethyleneglycol (EG) in water.This methodology is of interest due to the use of water as a solvent, thus minimizing the cost operational hazards, and environmental pollution.
2009, 20(10): 1179-1182
doi: 10.1016/j.cclet.2009.04.027
Abstract:
In our efforts to identify novel potent anticancer agents, we synthesized a series of 2,7-disubstituted triazolo[1,5-a]pyrimidines (6-16).Their antiproliferative activity against Bel-7402, HT-1080 and WI-38 cell lines was tested by MTTassay in vitro.Four of the compounds (9-11 and 16) displayed promising antiproliferative activity superior to gefitinib, especially compound 9.A preliminary SAR study of these derivatives was performed.
In our efforts to identify novel potent anticancer agents, we synthesized a series of 2,7-disubstituted triazolo[1,5-a]pyrimidines (6-16).Their antiproliferative activity against Bel-7402, HT-1080 and WI-38 cell lines was tested by MTTassay in vitro.Four of the compounds (9-11 and 16) displayed promising antiproliferative activity superior to gefitinib, especially compound 9.A preliminary SAR study of these derivatives was performed.
2009, 20(10): 1183-1186
doi: 10.1016/j.cclet.2009.04.039
Abstract:
3,4-Dihydropyrimidin-2(1H)-ones (DHPMs) were oxidized with 1.2 equiv.of nitrosonium tetrafluoroborate (NO+BF4-) topyrimidin-2(1H)-ones in acetonitrile at room temperature in high yields.
3,4-Dihydropyrimidin-2(1H)-ones (DHPMs) were oxidized with 1.2 equiv.of nitrosonium tetrafluoroborate (NO+BF4-) topyrimidin-2(1H)-ones in acetonitrile at room temperature in high yields.
2009, 20(10): 1187-1190
doi: 10.1016/j.cclet.2009.04.026
Abstract:
Four naturally rare 5,6,7-trimethoxy-2,3-cis-dihydroflavonols (3-6) and two 5,6,7-trimethoxy-2,3-trans-dihydroflavonols (7-8)were designed and synthesized.Their antioxidative properties were evaluated by way of examining their scavenging capacities towards DPPH and O2·-.free radicals, as well as by measuring their inhibitory ability against LPO.Both the 2,3-trans and the 2,3-cis conformers exhibited certain quenching abilities to DPPH and O2·- radicals, while most of the synthetic dihydroflavonols demonstrated remarkable inhibition to LPO.
Four naturally rare 5,6,7-trimethoxy-2,3-cis-dihydroflavonols (3-6) and two 5,6,7-trimethoxy-2,3-trans-dihydroflavonols (7-8)were designed and synthesized.Their antioxidative properties were evaluated by way of examining their scavenging capacities towards DPPH and O2·-.free radicals, as well as by measuring their inhibitory ability against LPO.Both the 2,3-trans and the 2,3-cis conformers exhibited certain quenching abilities to DPPH and O2·- radicals, while most of the synthetic dihydroflavonols demonstrated remarkable inhibition to LPO.
2009, 20(10): 1191-1194
doi: 10.1016/j.cclet.2009.05.002
Abstract:
An 2-aminopyridyl-bridged calix[6]arene on the upper rim fixed in cone conformation (3) was successfully synthesized and its highly selective recognition towards fluoride ion was proved by fluorescent and 1H NMR titration experiments.
An 2-aminopyridyl-bridged calix[6]arene on the upper rim fixed in cone conformation (3) was successfully synthesized and its highly selective recognition towards fluoride ion was proved by fluorescent and 1H NMR titration experiments.
2009, 20(10): 1195-1197
doi: 10.1016/j.cclet.2009.05.014
Abstract:
The bacillamide 1 is a new algaecide from the marine bacterium Bacillus sp.SY-1.Its analogues bacillamide 3 and alkaloid 4 were firstly synthesized effectively from D-alanine.The key step was a coupling reaction via the mixed anhydride.All structures were confirmed by 1H NMR and 13C NMR.The final compounds were confirmed by 1HNMR,13C NMR and HRMS and the results are consistent with the reported natural products.
The bacillamide 1 is a new algaecide from the marine bacterium Bacillus sp.SY-1.Its analogues bacillamide 3 and alkaloid 4 were firstly synthesized effectively from D-alanine.The key step was a coupling reaction via the mixed anhydride.All structures were confirmed by 1H NMR and 13C NMR.The final compounds were confirmed by 1HNMR,13C NMR and HRMS and the results are consistent with the reported natural products.
2009, 20(10): 1198-1200
doi: 10.1016/j.cclet.2009.05.027
Abstract:
A facile procedure for the synthesis of 2,4,5-triarylimidazoles is being reported starting from benzil, aromatic aldehyde and ammonium acetate.The reactions were carried out with catalyst-free, solvent-free and under microwave irradiation conditions in high yield (80-99%) with short time (3-5 min) and environmental benign, as well as convenient operation.The structures of the compounds have been confirmed on the basis of their IR,1H NMR, and/or 13C NMR, MS, and elemental analyzer.
A facile procedure for the synthesis of 2,4,5-triarylimidazoles is being reported starting from benzil, aromatic aldehyde and ammonium acetate.The reactions were carried out with catalyst-free, solvent-free and under microwave irradiation conditions in high yield (80-99%) with short time (3-5 min) and environmental benign, as well as convenient operation.The structures of the compounds have been confirmed on the basis of their IR,1H NMR, and/or 13C NMR, MS, and elemental analyzer.
2009, 20(10): 1201-1202
doi: 10.1016/j.cclet.2009.05.001
Abstract:
Quinazolinediones are particularly attractive pharmacophores because of their wide range of bioactivities.A convenient synthetic pathway to three-substituted quinazoline-2,4-dione derivatives was developed from substituted anthranilamide via carbonylation with Boc anhydride and then cyclization in the presence of the base sodium methoxide.Good to excellent yields have been achieved.
Quinazolinediones are particularly attractive pharmacophores because of their wide range of bioactivities.A convenient synthetic pathway to three-substituted quinazoline-2,4-dione derivatives was developed from substituted anthranilamide via carbonylation with Boc anhydride and then cyclization in the presence of the base sodium methoxide.Good to excellent yields have been achieved.
2009, 20(10): 1204-1206
doi: 10.1016/j.cclet.2009.05.024
Abstract:
(-)-7-Isopropyl-cis-1-amino-2-indanol, a key chiral auxiliary and ligand in the highly stereo-selective asymmetric 6π-azaelectrocyclization,has been prepared previously by two methods.Each however involved using of one extreme condition,i.e.high temperature or high pressure, for the respective reaction.A modified reaction route employed mild condition for synthesis was presented in this report.
(-)-7-Isopropyl-cis-1-amino-2-indanol, a key chiral auxiliary and ligand in the highly stereo-selective asymmetric 6π-azaelectrocyclization,has been prepared previously by two methods.Each however involved using of one extreme condition,i.e.high temperature or high pressure, for the respective reaction.A modified reaction route employed mild condition for synthesis was presented in this report.
2009, 20(10): 1207-1210
doi: 10.1016/j.cclet.2009.05.017
Abstract:
One new triterpenoid saponin, quinquenoside L 17 (1), was isolated from the leaves and stems of Panax quinquefolium L., and its structure was elucidated as 20-O-[(β-D-xylopyranosyl-(1-6)-O-β-D-glucopyranosyl)]-6-O-β-D-glucopyranosyl-dammar-24-ene3,6,12,20-tetraol, by the combination analysis of one-dimensional NMR and two-dimensional NMR, mass spectrometry, CD spectrum and chemical evidences.
One new triterpenoid saponin, quinquenoside L 17 (1), was isolated from the leaves and stems of Panax quinquefolium L., and its structure was elucidated as 20-O-[(β-D-xylopyranosyl-(1-6)-O-β-D-glucopyranosyl)]-6-O-β-D-glucopyranosyl-dammar-24-ene3,6,12,20-tetraol, by the combination analysis of one-dimensional NMR and two-dimensional NMR, mass spectrometry, CD spectrum and chemical evidences.
2009, 20(10): 1211-1214
doi: 10.1016/j.cclet.2009.06.002
Abstract:
Two new eudesmane sesquiterpene lactones were isolated from the stalk of Lactuca sativa var.anagustata L and their structures were elucidated by means of spectroscopic methods, including 2D NMR (1H-1H COSY, HMBC and NOESY) as 1β-O-β-Dglucopyranosyl-4a-hydroxyl-5a, 6β, 11βH-eudesma-12, 6α-olide (1) and 1β-hydroxyl-15-O-(-methoxyphenylacetyl)-5a, 6β,11bH-eudesma-3-en-12, 6a-olide (2).
Two new eudesmane sesquiterpene lactones were isolated from the stalk of Lactuca sativa var.anagustata L and their structures were elucidated by means of spectroscopic methods, including 2D NMR (1H-1H COSY, HMBC and NOESY) as 1β-O-β-Dglucopyranosyl-4a-hydroxyl-5a, 6β, 11βH-eudesma-12, 6α-olide (1) and 1β-hydroxyl-15-O-(-methoxyphenylacetyl)-5a, 6β,11bH-eudesma-3-en-12, 6a-olide (2).
2009, 20(10): 1215-1217
doi: 10.1016/j.cclet.2009.05.006
Abstract:
Two new phenolic glycosides, 2,3-dihydroxybenzoic acid methyl ester 3-O-β-D-glucopyranosyl-(1-6)-β-D-glucopyranoside (1)and 2,5-dihydroxylbenzofuran 5-O-β-D-xylopyranosyl-(1-6)-O-β-D-glucopyranoside (2), were isolated as the minor chemical constituents from the roots of Gentiana rigescens, along with 15 known compounds.Their structures were elucidated by detailed spectroscopic analysis, including 1D, 2D NMR and chemical method.All of these compounds were isolated for the first time from the title plant.Moreover, compounds 1 and 2 were tested for the antifungal activities on three plant pathogens Peronophythora litchi,Glomerella cingulata, and Glorosprium musarum
Two new phenolic glycosides, 2,3-dihydroxybenzoic acid methyl ester 3-O-β-D-glucopyranosyl-(1-6)-β-D-glucopyranoside (1)and 2,5-dihydroxylbenzofuran 5-O-β-D-xylopyranosyl-(1-6)-O-β-D-glucopyranoside (2), were isolated as the minor chemical constituents from the roots of Gentiana rigescens, along with 15 known compounds.Their structures were elucidated by detailed spectroscopic analysis, including 1D, 2D NMR and chemical method.All of these compounds were isolated for the first time from the title plant.Moreover, compounds 1 and 2 were tested for the antifungal activities on three plant pathogens Peronophythora litchi,Glomerella cingulata, and Glorosprium musarum
2009, 20(10): 1218-1220
doi: 10.1016/j.cclet.2009.05.020
Abstract:
Phytochemical investigation of the whole plants of Dicranostigma leptopodum (Maxim) Fedde has lead to the isolation of five alkaloids:dicranostigmine (1), isocorydine (2), corydine (3), protopine (4) and sinoacutine (5).Oxomorphine alkaloid (5) was isolated from the genus Dicranostigma for the first time and the new compound structure (1) was elucidated by various spectroscopic methods including 2D NMR techniques (gCOSY, HMQC, HMBC and NOESY) and HRESI-MS.
Phytochemical investigation of the whole plants of Dicranostigma leptopodum (Maxim) Fedde has lead to the isolation of five alkaloids:dicranostigmine (1), isocorydine (2), corydine (3), protopine (4) and sinoacutine (5).Oxomorphine alkaloid (5) was isolated from the genus Dicranostigma for the first time and the new compound structure (1) was elucidated by various spectroscopic methods including 2D NMR techniques (gCOSY, HMQC, HMBC and NOESY) and HRESI-MS.
2009, 20(10): 1221-1223
doi: 10.1016/j.cclet.2009.05.032
Abstract:
One new monoterpenoid indole alkaloid, 11-methoxyburnamine-17-O-3',4',5'-trimethoxybenzoate (1), was isolated from Rauvolfia yunnanensis Tsiang.Its structure was identified by spectroscopic evidences.
One new monoterpenoid indole alkaloid, 11-methoxyburnamine-17-O-3',4',5'-trimethoxybenzoate (1), was isolated from Rauvolfia yunnanensis Tsiang.Its structure was identified by spectroscopic evidences.
2009, 20(10): 1227-1230
doi: 10.1016/j.cclet.2009.05.031
Abstract:
Two new 24-hydroxylated asterosaponins, sodium (20R,24S)-6α-O-(4-O-sodiumsulfato-β-D-quinovopyranosyl)-5a-cholest9(11)-en-3b,24-diol 3-sulfate (1) and sodium (20R,24S)-6α-O-[3-O-methyl-b-D-quinovopyranosyl-(1→2)-β-D-xylopyranosyl(1→3)-β-D-glucopyranosyl]-5a-cholest-9(11)-en-3β,24-diol 3-sulfate (2), were isolated from the starfish Culcita novaeguineae.Their structures were elucidated by extensive spectral analysis and chemical evidences.
Two new 24-hydroxylated asterosaponins, sodium (20R,24S)-6α-O-(4-O-sodiumsulfato-β-D-quinovopyranosyl)-5a-cholest9(11)-en-3b,24-diol 3-sulfate (1) and sodium (20R,24S)-6α-O-[3-O-methyl-b-D-quinovopyranosyl-(1→2)-β-D-xylopyranosyl(1→3)-β-D-glucopyranosyl]-5a-cholest-9(11)-en-3β,24-diol 3-sulfate (2), were isolated from the starfish Culcita novaeguineae.Their structures were elucidated by extensive spectral analysis and chemical evidences.
2009, 20(10): 1231-1234
doi: 10.1016/j.cclet.2009.05.012
Abstract:
A new polyhydroxysteroidal glycoside, (20R,24R)-16-O-(4-O-methyl-2-acetamido-2-deoxy-β-D-galactopyranosyl)-24-ethyl5a-cholest-8(14)-en-3β,6β,7β,16α-tetrol (anthenoside A, 1), was isolated from the starfish Anthenea chinensis.Its structure was elucidated by extensive spectral analysis and chemical evidences.1 exhibited significant cytotoxicity against human tumor K-562,BEL-7402 and U87MG cells.
A new polyhydroxysteroidal glycoside, (20R,24R)-16-O-(4-O-methyl-2-acetamido-2-deoxy-β-D-galactopyranosyl)-24-ethyl5a-cholest-8(14)-en-3β,6β,7β,16α-tetrol (anthenoside A, 1), was isolated from the starfish Anthenea chinensis.Its structure was elucidated by extensive spectral analysis and chemical evidences.1 exhibited significant cytotoxicity against human tumor K-562,BEL-7402 and U87MG cells.
2009, 20(10): 1241-1244
doi: 10.1016/j.cclet.2009.05.003
Abstract:
A novel method for determination of formaldehyde sulfoxylate, sulfite, thiocyanate, and thiosulfate in foodstuffs by ion chromatography separation with postcolumn derivation and UV detection has been developed.All species are separated at Dionex IonPac AG22A and AS22Awith mobile phase of a mixture of 4.5 mmol/L sodium carbonate and 0.8 mmol/L sodium bicarbonate at a flow-rate of 1.0 mL/min.The postcolumn derivation solution was 0.24% iodine in 0.2% phosphate acid and the detection wavelength was set at 288 nm.The detection limits (LOD, signal-to-noise ratio of 3) of formaldehyde sulfoxylate, sulfite,thiocyanate, and thiosulfate were 0.004, 0.006, 0.006, and 0.007 mg/L, respectively.Within-day relative standard deviations (RSD,n=10) of formaldehyde sulfoxylate, sulfite, thiocyanate, and thiosulfate were 3.24%, 3.76%, 2.68%, and 2.07%, respectively.The recoveries of the four anions were in the range of 67.2-116.5%.
A novel method for determination of formaldehyde sulfoxylate, sulfite, thiocyanate, and thiosulfate in foodstuffs by ion chromatography separation with postcolumn derivation and UV detection has been developed.All species are separated at Dionex IonPac AG22A and AS22Awith mobile phase of a mixture of 4.5 mmol/L sodium carbonate and 0.8 mmol/L sodium bicarbonate at a flow-rate of 1.0 mL/min.The postcolumn derivation solution was 0.24% iodine in 0.2% phosphate acid and the detection wavelength was set at 288 nm.The detection limits (LOD, signal-to-noise ratio of 3) of formaldehyde sulfoxylate, sulfite,thiocyanate, and thiosulfate were 0.004, 0.006, 0.006, and 0.007 mg/L, respectively.Within-day relative standard deviations (RSD,n=10) of formaldehyde sulfoxylate, sulfite, thiocyanate, and thiosulfate were 3.24%, 3.76%, 2.68%, and 2.07%, respectively.The recoveries of the four anions were in the range of 67.2-116.5%.
2009, 20(10): 1245-1247
doi: 10.1016/j.cclet.2009.04.025
Abstract:
A La3+-Cu/Pt modified electrode was fabricated by electrodepositing process in CuSO 4 solution by adding a small amount oflanthium compound, and it was employed for direct current (DC) amperometric detection of spectinomycin by anion-exchange chromatography.Without derivatization, this method can simultaneously determine the main component and impurities in spectinomycin pharmaceutical raw material.Ease of preparation, being applied in DC detection mode and good catalytic stability confirmed the interests of this modified electrode as amperometric sensor for the determination of spectinomycin.
A La3+-Cu/Pt modified electrode was fabricated by electrodepositing process in CuSO 4 solution by adding a small amount oflanthium compound, and it was employed for direct current (DC) amperometric detection of spectinomycin by anion-exchange chromatography.Without derivatization, this method can simultaneously determine the main component and impurities in spectinomycin pharmaceutical raw material.Ease of preparation, being applied in DC detection mode and good catalytic stability confirmed the interests of this modified electrode as amperometric sensor for the determination of spectinomycin.
2009, 20(10): 1248-1250
doi: 10.1016/j.cclet.2009.04.019
Abstract:
Multi-walled carbon nanotube multilayers were modified onto a newly proposed gold hair microelectrode via a simple layer-bylayer assembling method.The resulting electrode showed a sensitive oxidation response to estradiol with detection limit as low as 1.0×10-8mol/L, foreseeing a promising approach to the fabrication of high-sensitive microsensors.
Multi-walled carbon nanotube multilayers were modified onto a newly proposed gold hair microelectrode via a simple layer-bylayer assembling method.The resulting electrode showed a sensitive oxidation response to estradiol with detection limit as low as 1.0×10-8mol/L, foreseeing a promising approach to the fabrication of high-sensitive microsensors.
2009, 20(10): 1251-1254
doi: 10.1016/j.cclet.2009.05.007
Abstract:
Wormlike micelles, obtained in anionic surfactant sodium oleate (NaOA) solutions in the presence of sodium phosphate (Na 3 PO 4), were studied using the steady and dynamic rheological methods.The laboratory simulation flooding experiments were used to investigate the effects of flooding for the wormlike micelles system.The results show that the oil recovery is 32.7%.This flooding system is a new type and has high activity with a low cost.
Wormlike micelles, obtained in anionic surfactant sodium oleate (NaOA) solutions in the presence of sodium phosphate (Na 3 PO 4), were studied using the steady and dynamic rheological methods.The laboratory simulation flooding experiments were used to investigate the effects of flooding for the wormlike micelles system.The results show that the oil recovery is 32.7%.This flooding system is a new type and has high activity with a low cost.
Electrochemical performance of sulfur composite cathode materials for rechargeable lithium batteries
2009, 20(10): 1255-1258
doi: 10.1016/j.cclet.2009.04.036
Abstract:
The structure and characteristic of carbon materials have a direct influence on the electrochemical performance of sulfur-carbon composite eleceof elemental sulfur and activated carbon, which is characterized as high specific surface area and microporous structure.The composite, contained 70% sulfur, as cathode in a lithium cell based on organic liquid electrolyte was tested at room temperature.It showed two reduction peaks at 2.05 V and 2.35 V, one oxidation peak at 2.4 V during cyclic voltammogram test.The initial discharge specific capacity was 1180.8 mAh g -1 and the utilization of electrochemically active sulfur was about 70.6% assuming a complete reaction to the product of Li 2S.The specific capacity still kept as high as 720.4 mAh g-1after 60 cycles retaining 61% of the initial discharge capacity.
The structure and characteristic of carbon materials have a direct influence on the electrochemical performance of sulfur-carbon composite eleceof elemental sulfur and activated carbon, which is characterized as high specific surface area and microporous structure.The composite, contained 70% sulfur, as cathode in a lithium cell based on organic liquid electrolyte was tested at room temperature.It showed two reduction peaks at 2.05 V and 2.35 V, one oxidation peak at 2.4 V during cyclic voltammogram test.The initial discharge specific capacity was 1180.8 mAh g -1 and the utilization of electrochemically active sulfur was about 70.6% assuming a complete reaction to the product of Li 2S.The specific capacity still kept as high as 720.4 mAh g-1after 60 cycles retaining 61% of the initial discharge capacity.
2009, 20(10): 1259-1262
doi: 10.1016/j.cclet.2009.04.030
Abstract:
New supramolecular hydrogels with the maximal sol-gel transition temperature (Tgel) of 95℃ were obtained by using gelators formed from 1,3,5-benzenetricarboxylic acid (BTA) and para-hydroxyl pyridine (PHP) or meta-hydroxyl pyridine (MHP).Thesingle crystal structure of the complex formed from BTA and ortho-hydroxyl pyridine (OHP) indicated that the molecules assembled into superstructure via both hydrogen bonds and π-πstacking interaction.
New supramolecular hydrogels with the maximal sol-gel transition temperature (Tgel) of 95℃ were obtained by using gelators formed from 1,3,5-benzenetricarboxylic acid (BTA) and para-hydroxyl pyridine (PHP) or meta-hydroxyl pyridine (MHP).Thesingle crystal structure of the complex formed from BTA and ortho-hydroxyl pyridine (OHP) indicated that the molecules assembled into superstructure via both hydrogen bonds and π-πstacking interaction.
2009, 20(10): 1263-1266
doi: 10.1016/j.cclet.2009.05.018
Abstract:
An initial model of the HBV epsilon RNA was built by the Biopolymer module of Insight Ⅱ.While its three-dimensional structure was obtained through structure optimization based on molecular dynamics simulation, the two active sites were found.A comparison with the experimental result indicated that the active sites may be the binding sites of the epsilon RNA in the RT-epsilon interaction.The result will be helpful to further discussion about the mechanism of RT-epsilon interaction and the study of HBV genome replication.
An initial model of the HBV epsilon RNA was built by the Biopolymer module of Insight Ⅱ.While its three-dimensional structure was obtained through structure optimization based on molecular dynamics simulation, the two active sites were found.A comparison with the experimental result indicated that the active sites may be the binding sites of the epsilon RNA in the RT-epsilon interaction.The result will be helpful to further discussion about the mechanism of RT-epsilon interaction and the study of HBV genome replication.
