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2008 Volume 19 Issue 8
2008, 19(8): 885-888
doi: 10.1016/j.cclet.2008.05.031
Abstract:
The reagent combination of Hantzsch 1,4-dihydropyridine and Pd/C was found to be an efficient reducing system for the selective reduction of aromatic azides.
The reagent combination of Hantzsch 1,4-dihydropyridine and Pd/C was found to be an efficient reducing system for the selective reduction of aromatic azides.
2008, 19(8): 889-892
doi: 10.1016/j.cclet.2008.04.035
Abstract:
Brønsted acidic ionic liquids based on imidazolium cation were employed as a series of environmentally benign catalysts and mediums in the alcoholysis of acetonitrile to synthesize ester.The results showed that Brønsted acidic ionic liquid [HSO3-pmim]HSO4 was an efficient catalyst and medium for the alcoholysis of acetonitrile which could be recycled easily without obvious decline in catalytic activity, the highest yield could reach 85%.
Brønsted acidic ionic liquids based on imidazolium cation were employed as a series of environmentally benign catalysts and mediums in the alcoholysis of acetonitrile to synthesize ester.The results showed that Brønsted acidic ionic liquid [HSO3-pmim]HSO4 was an efficient catalyst and medium for the alcoholysis of acetonitrile which could be recycled easily without obvious decline in catalytic activity, the highest yield could reach 85%.
2008, 19(8): 893-896
doi: 10.1016/j.cclet.2008.04.042
Abstract:
A simple, green and efficient method for the DHP protection of various alcohols and phenols and the subsequent removal of the corresponding protective group in the presence of a catalytic amount of the activated carbon supported H2SO4 is described.
A simple, green and efficient method for the DHP protection of various alcohols and phenols and the subsequent removal of the corresponding protective group in the presence of a catalytic amount of the activated carbon supported H2SO4 is described.
2008, 19(8): 897-900
doi: 10.1016/j.cclet.2008.05.045
Abstract:
Cobalt methanesulfonate in combination with acetic acid catalysed the chemoselective diacetylation of aldehyde with acetic anhydride at room temperature under solvent free conditions.After reaction, cobalt methanesulfonate can be easily recovered and mused many times.The reaction was mild and efficient with good to high yields.
Cobalt methanesulfonate in combination with acetic acid catalysed the chemoselective diacetylation of aldehyde with acetic anhydride at room temperature under solvent free conditions.After reaction, cobalt methanesulfonate can be easily recovered and mused many times.The reaction was mild and efficient with good to high yields.
2008, 19(8): 901-903
doi: 10.1016/j.cclet.2008.05.035
Abstract:
Four novel calix[4]arene derivatives 5-8 bearing four fluorogenic coumarin units attached via imino group acting also as binding sites at the upper rim have been prepared and characterized by IR, 1H NMR and MS.Compounds 5-8 adopt a cone conformation.Their complexation properties to different heavy and transition metal ions have been studied by UV-vis spectroscopy.Compounds 5, 6, 8 show selective recognition to Fe3+ and Cr3+.
Four novel calix[4]arene derivatives 5-8 bearing four fluorogenic coumarin units attached via imino group acting also as binding sites at the upper rim have been prepared and characterized by IR, 1H NMR and MS.Compounds 5-8 adopt a cone conformation.Their complexation properties to different heavy and transition metal ions have been studied by UV-vis spectroscopy.Compounds 5, 6, 8 show selective recognition to Fe3+ and Cr3+.
2008, 19(8): 904-906
doi: 10.1016/j.cclet.2008.05.047
Abstract:
School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
2008, 19(8): 907-910
doi: 10.1016/j.cclet.2008.05.036
Abstract:
Treatment of N-t-butylbenzenesulfonamide with an excess of BuLi, followed by the reaction with methyl 2-(4-methylphenyl)propanoate, gave the corresponding 2-carboxybenzenesulfonamide, which underwent a sequence of consecutive N-deprotective cyclization process mediated by TMSCl-NaI-MeCN reagent to afford the N-sulfonylimine.Following the bromination and ring expansion, 3-methyl-3-(4-methylphenyl)-2H-benzo[e][1,2]thiazine-1,1,4-trione was obtained.Optical resolution of the racemic benzosultam using (-)-menthoxyacetyl chloride, furnished the optically pure (+)-and (-)-3-methyl-3-(4-methylphenyl)-2H-benzo[e][1,2]thiazine-1,1,4-triones, which were fluorinated with FClO3 to produce the corresponding chiral N-F agents.
Treatment of N-t-butylbenzenesulfonamide with an excess of BuLi, followed by the reaction with methyl 2-(4-methylphenyl)propanoate, gave the corresponding 2-carboxybenzenesulfonamide, which underwent a sequence of consecutive N-deprotective cyclization process mediated by TMSCl-NaI-MeCN reagent to afford the N-sulfonylimine.Following the bromination and ring expansion, 3-methyl-3-(4-methylphenyl)-2H-benzo[e][1,2]thiazine-1,1,4-trione was obtained.Optical resolution of the racemic benzosultam using (-)-menthoxyacetyl chloride, furnished the optically pure (+)-and (-)-3-methyl-3-(4-methylphenyl)-2H-benzo[e][1,2]thiazine-1,1,4-triones, which were fluorinated with FClO3 to produce the corresponding chiral N-F agents.
2008, 19(8): 911-914
doi: 10.1016/j.cclet.2008.05.038
Abstract:
A convenient synthetic method with high yields for aryl-incorporated ditosylates by reaction of aryl-incorporated diols with TsCl in THF/NaOH/H20 solution was described.Some of these aryl-incorporated ditosylates reacted with diphenols to produce crown ethers in pleasant yield.
A convenient synthetic method with high yields for aryl-incorporated ditosylates by reaction of aryl-incorporated diols with TsCl in THF/NaOH/H20 solution was described.Some of these aryl-incorporated ditosylates reacted with diphenols to produce crown ethers in pleasant yield.
2008, 19(8): 915-917
doi: 10.1016/j.cclet.2008.05.020
Abstract:
A one-pot synthesis of 2-(1-acyloxypentyl) benzoic acids by trapping the carboxylate/alkoxide dianion with acylating reagents following Grignard addition with n-BuMgBr to 2-formylbenzoic acid was described.Compared with routine synthetic method, this novel procedure has the advantage of convenient operation and higher yields.
A one-pot synthesis of 2-(1-acyloxypentyl) benzoic acids by trapping the carboxylate/alkoxide dianion with acylating reagents following Grignard addition with n-BuMgBr to 2-formylbenzoic acid was described.Compared with routine synthetic method, this novel procedure has the advantage of convenient operation and higher yields.
2008, 19(8): 918-920
doi: 10.1016/j.cclet.2008.05.042
Abstract:
A novel camptothecin analogue, 9-methyl-10-hydroxycamptothecin (4), was unexpectedly synthesized from 10-hydroxycamptothecin in two steps.The key step included an efficient Mannich-type reaction.The overall yield was 47.2%.An ether analogue of 4, 9-methyl-10-benzylaminomethoxycamptothecin (5), was also prepared.These new camptothecin analogues were evaluated for in vitro cytotoxicity against four human cancer cell lines, and exhibited more potent antitumor activities than contrals camptothecin and topotecan against several cancer cells.
A novel camptothecin analogue, 9-methyl-10-hydroxycamptothecin (4), was unexpectedly synthesized from 10-hydroxycamptothecin in two steps.The key step included an efficient Mannich-type reaction.The overall yield was 47.2%.An ether analogue of 4, 9-methyl-10-benzylaminomethoxycamptothecin (5), was also prepared.These new camptothecin analogues were evaluated for in vitro cytotoxicity against four human cancer cell lines, and exhibited more potent antitumor activities than contrals camptothecin and topotecan against several cancer cells.
2008, 19(8): 921-924
doi: 10.1016/j.cclet.2008.05.008
Abstract:
The one-pot aza-Diels-Alder reaction of substituted aromatic amines, ethyl glyoxylate and benzyl vinylcarbamate or N-benzyloxycarbonyl 2-pyrroline was conducted in hexafluoroisopropanol, providing the desired 1,2,3,4-tetrahydroquinline derivatives in moderate yields.
The one-pot aza-Diels-Alder reaction of substituted aromatic amines, ethyl glyoxylate and benzyl vinylcarbamate or N-benzyloxycarbonyl 2-pyrroline was conducted in hexafluoroisopropanol, providing the desired 1,2,3,4-tetrahydroquinline derivatives in moderate yields.
2008, 19(8): 925-927
doi: 10.1016/j.cclet.2008.05.043
Abstract:
Twelve S-substituted 7-mercapto-4-methylcoumarin analogs were synthesized and evaluated for the inhibition to HBV in HepG2 2.2.1.5 cell.Among them, ten compounds exhibited potent inhibition to HBsAg and/or HBeAg with the IC50 values of subμmol/L level.The IC50 of anti-HBsAg activities of 5c and 5j reached 0.01 μmol/L respectively which were 16 fold more potent than that of 3TC.Compounds 3, 5e, 5g, 5h and 5i showed admirable inhibitory activity to both HBsAg and HBeAg.The bioassay results indicated the S-substituted 7-mercapto-4-methylcoumarin analogs merit attention as novel anti-HBV agents.
Twelve S-substituted 7-mercapto-4-methylcoumarin analogs were synthesized and evaluated for the inhibition to HBV in HepG2 2.2.1.5 cell.Among them, ten compounds exhibited potent inhibition to HBsAg and/or HBeAg with the IC50 values of subμmol/L level.The IC50 of anti-HBsAg activities of 5c and 5j reached 0.01 μmol/L respectively which were 16 fold more potent than that of 3TC.Compounds 3, 5e, 5g, 5h and 5i showed admirable inhibitory activity to both HBsAg and HBeAg.The bioassay results indicated the S-substituted 7-mercapto-4-methylcoumarin analogs merit attention as novel anti-HBV agents.
2008, 19(8): 928-930
doi: 10.1016/j.cclet.2008.05.044
Abstract:
In search of novel anticancer agents, a series of thalidomide analogs (6a-j) were designed and synthesized.Cytotoxicity of these compounds against human hepatoma cells (HepG2) was evaluated by MTT method.Compounds 6d, 6h and 6i showed significant cytotoxic activities comparable to or stronger than control 5-fluorouracil.
In search of novel anticancer agents, a series of thalidomide analogs (6a-j) were designed and synthesized.Cytotoxicity of these compounds against human hepatoma cells (HepG2) was evaluated by MTT method.Compounds 6d, 6h and 6i showed significant cytotoxic activities comparable to or stronger than control 5-fluorouracil.
2008, 19(8): 931-933
doi: 10.1016/j.cclet.2008.05.030
Abstract:
Two new alkaloids, uncaric acid A and hirsutaside A, were isolated from Uncaria hirsuta.Their structures were determined by spectroscopic evidences and chemical means.
Two new alkaloids, uncaric acid A and hirsutaside A, were isolated from Uncaria hirsuta.Their structures were determined by spectroscopic evidences and chemical means.
2008, 19(8): 934-936
doi: 10.1016/j.cclet.2008.05.034
Abstract:
A new compound 8-chloro-5,6,7-trihydroxy-2-(3-hydroxy-4-methoxyphenethyl)-5,6,7,8-tetrahydro-4H-chromen-4-one (1) was isolated from the Chinese eaglewood [Aquilaria sinensis (Lour.) Gilg].Its structure was elucidated on the basis of spectral data.Compound 1 showed cytotoxicity against human gastric cancer cell line (SGC-7901) in vitro by MTT method with the IC50 value of 14.6 μg/mL.
A new compound 8-chloro-5,6,7-trihydroxy-2-(3-hydroxy-4-methoxyphenethyl)-5,6,7,8-tetrahydro-4H-chromen-4-one (1) was isolated from the Chinese eaglewood [Aquilaria sinensis (Lour.) Gilg].Its structure was elucidated on the basis of spectral data.Compound 1 showed cytotoxicity against human gastric cancer cell line (SGC-7901) in vitro by MTT method with the IC50 value of 14.6 μg/mL.
2008, 19(8): 937-939
doi: 10.1016/j.cclet.2008.05.046
Abstract:
A new sesterterpenoid phellogine was isolated from the fruits of Phellodendron chinense var glabriusculum Schneid.Its structure was elucidated on the basis of spectral analysis.
A new sesterterpenoid phellogine was isolated from the fruits of Phellodendron chinense var glabriusculum Schneid.Its structure was elucidated on the basis of spectral analysis.
2008, 19(8): 940-942
doi: 10.1016/j.cclet.2008.05.037
Abstract:
A new dimeric psoralen-type furanocoumarin, notopterol-(18-O-20')-notopol (1), was isolated from Notopterygium incisum for the first time and its structure was elucidated by spectroscopic methods.
A new dimeric psoralen-type furanocoumarin, notopterol-(18-O-20')-notopol (1), was isolated from Notopterygium incisum for the first time and its structure was elucidated by spectroscopic methods.
2008, 19(8): 943-946
doi: 10.1016/j.cclet.2008.04.048
Abstract:
Two new compounds 7-hydroxy-5-O-(b-D-glucopyranoside) flavan (1) and (Z)-4',6'-dihydroxy-2'-O-(b-D-glucopyranoside) chalcone (2), along with eight known compounds, were isolated from the stem bark of Drypetes parvifolia (Euphorbiaceae).Their structures were established on the basis of spectroscopic analysis and chemical evidence
Two new compounds 7-hydroxy-5-O-(b-D-glucopyranoside) flavan (1) and (Z)-4',6'-dihydroxy-2'-O-(b-D-glucopyranoside) chalcone (2), along with eight known compounds, were isolated from the stem bark of Drypetes parvifolia (Euphorbiaceae).Their structures were established on the basis of spectroscopic analysis and chemical evidence
2008, 19(8): 947-950
doi: 10.1016/j.cclet.2008.05.032
Abstract:
Monoamine oxidase is flavoenzymes, widely distributed in mammals.It is well recognized that MAOs serve an important role in metabolism that they have close relationship with health.Along with the discoveries between MAOs and neurotic disease, more and more studies have been jumped in.In this paper, we design a new probe for assaying the activities of MAOs.The results showed that the probe [7-(3-aminopropoxy)coumarin] is simple, effective and sensitive for MAOB.
Monoamine oxidase is flavoenzymes, widely distributed in mammals.It is well recognized that MAOs serve an important role in metabolism that they have close relationship with health.Along with the discoveries between MAOs and neurotic disease, more and more studies have been jumped in.In this paper, we design a new probe for assaying the activities of MAOs.The results showed that the probe [7-(3-aminopropoxy)coumarin] is simple, effective and sensitive for MAOB.
2008, 19(8): 951-954
doi: 10.1016/j.cclet.2008.05.014
Abstract:
The inclusion interaction between three types of methylated-β-cyclodextrins (Me-β-CDs) and albendazole (ABZ) was studied by spectrofluorimetry.The result showed that Me-β-CDs reacted with ABZ to form an inclusion complex, 1:1 stoichiometry for Me-β-CDs-ABZ complex was established and its association constant have been determined from fluorescence data by Benesi-Hildebrand's method (double reciprocal plots).It was noted that 2,6-DM-β-CD exhibited stronger binding ability than other Me-β-CDs.Based on the significant enhancement of fluorescence intensity of inclusion complex, a simple and highly sensitive fluorimetric method is proposed for the determination of ABZ in the presence of 2,6-DM-β-CD.The proposed method was successfully applied to the determination of ABZ in tablets and human urine.
The inclusion interaction between three types of methylated-β-cyclodextrins (Me-β-CDs) and albendazole (ABZ) was studied by spectrofluorimetry.The result showed that Me-β-CDs reacted with ABZ to form an inclusion complex, 1:1 stoichiometry for Me-β-CDs-ABZ complex was established and its association constant have been determined from fluorescence data by Benesi-Hildebrand's method (double reciprocal plots).It was noted that 2,6-DM-β-CD exhibited stronger binding ability than other Me-β-CDs.Based on the significant enhancement of fluorescence intensity of inclusion complex, a simple and highly sensitive fluorimetric method is proposed for the determination of ABZ in the presence of 2,6-DM-β-CD.The proposed method was successfully applied to the determination of ABZ in tablets and human urine.
2008, 19(8): 955-958
doi: 10.1016/j.cclet.2008.04.023
Abstract:
A novel hydrogen peroxide biosensor has been fabricated based on covalently linked horseradish peroxidase (HRP) onto Lglutathione self-assembled monolayers (SAMs).The SAMs-based electrode was characterized by electrochemical methods, and direct electrochemistry of HRP can be achieved with formal potential of-0.242 V (vs.saturated Ag/AgCl) in pH7 phosphate buffer solution (PBS), the redox peak current is linear to scan rate and rate constant can be calculated to be 0.042 s-1.The HRP-SAMs-based biosensors show its better electrocatalysis to hydrogen peroxide in the concentration range of 1×10-6 mol/L to 1.2×10-3 mol/L with a detection limit of 4×10-7 mol/L.The apparent Michealis-Menten constant is 3.12 mmol/L.The biosensor can effectively eliminate the interferences of dopamine, ascorbic acid, uric acid, catechol and p-acetaminophen.
A novel hydrogen peroxide biosensor has been fabricated based on covalently linked horseradish peroxidase (HRP) onto Lglutathione self-assembled monolayers (SAMs).The SAMs-based electrode was characterized by electrochemical methods, and direct electrochemistry of HRP can be achieved with formal potential of-0.242 V (vs.saturated Ag/AgCl) in pH7 phosphate buffer solution (PBS), the redox peak current is linear to scan rate and rate constant can be calculated to be 0.042 s-1.The HRP-SAMs-based biosensors show its better electrocatalysis to hydrogen peroxide in the concentration range of 1×10-6 mol/L to 1.2×10-3 mol/L with a detection limit of 4×10-7 mol/L.The apparent Michealis-Menten constant is 3.12 mmol/L.The biosensor can effectively eliminate the interferences of dopamine, ascorbic acid, uric acid, catechol and p-acetaminophen.
2008, 19(8): 959-961
doi: 10.1016/j.cclet.2008.05.033
Abstract:
An improved electrochemiluminescence polymerase chain reaction (ECL-PCR) method was developed and applied to detect Fusarium wilt.Briefly, the internal transcribed spacer (ITS) sequence of Fusarium oxysporum f.sp Cubense (FOC) was amplified by PCR.Two universal fragments, which were complimentary to Ru(bpy)32+ (TBR) labeled probe and Biotin labeled probe, respectively, were connected to the tail of primers so that all the PCR products got universal sequences.Then biotin labeled probes and TBR labeled probes were hybridized with the PCR products at the same time.Through the specific interaction between biotin and streptavidin, the PCR products were captured by streptavidin coated magnetic bead and then detected by ECL assay.The experiment results showed that the healthy banana samples and infected ones can be discriminated by this ECL-PCR method.This improved ECL-PCR approach is useful in Fusarium wilt detection due to its high sensitivity, simplicity and stability.
An improved electrochemiluminescence polymerase chain reaction (ECL-PCR) method was developed and applied to detect Fusarium wilt.Briefly, the internal transcribed spacer (ITS) sequence of Fusarium oxysporum f.sp Cubense (FOC) was amplified by PCR.Two universal fragments, which were complimentary to Ru(bpy)32+ (TBR) labeled probe and Biotin labeled probe, respectively, were connected to the tail of primers so that all the PCR products got universal sequences.Then biotin labeled probes and TBR labeled probes were hybridized with the PCR products at the same time.Through the specific interaction between biotin and streptavidin, the PCR products were captured by streptavidin coated magnetic bead and then detected by ECL assay.The experiment results showed that the healthy banana samples and infected ones can be discriminated by this ECL-PCR method.This improved ECL-PCR approach is useful in Fusarium wilt detection due to its high sensitivity, simplicity and stability.
2008, 19(8): 962-964
doi: 10.1016/j.cclet.2008.05.027
Abstract:
A novel method for the determination of two quinolone drugs norfloxacin (NOR) and levofloxacin (LVX) was described by capillary electrophoresis with electrochemiluminescence detection.The good relationship (r≥0.9991) between peak area and concentration of analytes was established over two orders of magnitude.The limits of detection (LOD, S/N=3) in standard solution are 4.8×10-7 mol/L for NOR and 6.4×10-7mol/L for LVX, respectively.The limits of quantitation (LOQ, S/N=10) in real human urine samples are 1.2×10-6 mol/L for NOR and 1.4×10-6 mol/L for LVX, respectively.The present method was successfully applied to the determination of NOR and LVX in human urine and the study of pharmacokinetics of NOR.
A novel method for the determination of two quinolone drugs norfloxacin (NOR) and levofloxacin (LVX) was described by capillary electrophoresis with electrochemiluminescence detection.The good relationship (r≥0.9991) between peak area and concentration of analytes was established over two orders of magnitude.The limits of detection (LOD, S/N=3) in standard solution are 4.8×10-7 mol/L for NOR and 6.4×10-7mol/L for LVX, respectively.The limits of quantitation (LOQ, S/N=10) in real human urine samples are 1.2×10-6 mol/L for NOR and 1.4×10-6 mol/L for LVX, respectively.The present method was successfully applied to the determination of NOR and LVX in human urine and the study of pharmacokinetics of NOR.
2008, 19(8): 965-968
doi: 10.1016/j.cclet.2008.04.027
Abstract:
TiO2 nanoparticles were homogeneously coated on multi-walled carbon nanotubes by hydrothermal deposition, this nano-composite may be a promising material for myoglobin immobilization in view of its high biocompatibility and large surface.The glassy carbon electrode modified with Mb-TiO2/MWCNTs films exhibited a pair of well defined, stable and nearly reversible cycle voltammetric peaks.The electron transfer between Mb and electrode surface, Ks of 3.08 s-1, was greatly facilitated in the TiO2/MWCNTs film.The electrocatalytic reductions of hydrogen peroxide were studied, the apparent Michaelis-Menten constant is calculated to be 83.10 μmol/L, which shows a large catalytic activity of Mb in the TiO2/MWCNTs film to H2O2.
TiO2 nanoparticles were homogeneously coated on multi-walled carbon nanotubes by hydrothermal deposition, this nano-composite may be a promising material for myoglobin immobilization in view of its high biocompatibility and large surface.The glassy carbon electrode modified with Mb-TiO2/MWCNTs films exhibited a pair of well defined, stable and nearly reversible cycle voltammetric peaks.The electron transfer between Mb and electrode surface, Ks of 3.08 s-1, was greatly facilitated in the TiO2/MWCNTs film.The electrocatalytic reductions of hydrogen peroxide were studied, the apparent Michaelis-Menten constant is calculated to be 83.10 μmol/L, which shows a large catalytic activity of Mb in the TiO2/MWCNTs film to H2O2.
2008, 19(8): 969-972
doi: 10.1016/j.cclet.2008.04.028
Abstract:
An analytical method was developed using a solid phase extraction (SPE) cleanup and gas chromatography for detecting the residues of difenoconazole in Chinese cabbage and soil.The recovery and the relative standard deviation of this method in Chinese cabbage was 87.6-99.0%, 1.71-10.50%, respectively; in soil was 92.4-95.5%, 4.93-10.70%, respectively.Further degradation of difenoconazole residue in Chinese cabbage and soil was studied to evaluate residue behavior and environmental safety of difenoconazole.Degradation rate of difenoconazole in both Chinese cabbage and soil followed the first order kinetics with the half-lives of 6.6-7.8 and 54.2-55.0 days, respectively.
An analytical method was developed using a solid phase extraction (SPE) cleanup and gas chromatography for detecting the residues of difenoconazole in Chinese cabbage and soil.The recovery and the relative standard deviation of this method in Chinese cabbage was 87.6-99.0%, 1.71-10.50%, respectively; in soil was 92.4-95.5%, 4.93-10.70%, respectively.Further degradation of difenoconazole residue in Chinese cabbage and soil was studied to evaluate residue behavior and environmental safety of difenoconazole.Degradation rate of difenoconazole in both Chinese cabbage and soil followed the first order kinetics with the half-lives of 6.6-7.8 and 54.2-55.0 days, respectively.
2008, 19(8): 973-976
doi: 10.1016/j.cclet.2008.05.022
Abstract:
A capillary electrophoresis method with UV detection was developed for high sensitively determining genistein.In this method, the online acid barrage stacking was applied.Four key factors influencing the stacking efficiency were systematically optimized.Genistein can be detected within 5 rain at the concentration of 10 nmol/L, which was 300 times lower than that from conventional hydrodynamic injection.The repeatability, linear range, and limit of detection of the method were investigated with satisfactory result.
A capillary electrophoresis method with UV detection was developed for high sensitively determining genistein.In this method, the online acid barrage stacking was applied.Four key factors influencing the stacking efficiency were systematically optimized.Genistein can be detected within 5 rain at the concentration of 10 nmol/L, which was 300 times lower than that from conventional hydrodynamic injection.The repeatability, linear range, and limit of detection of the method were investigated with satisfactory result.
2008, 19(8): 977-980
doi: 10.1016/j.cclet.2008.05.010
Abstract:
A novel chemosensor 1 (CS1) bearing one coumarin and two carbodithioate groups was synthesized and its fluorescent sensing behavior toward metal ions was investigated.Ag+ addition to a CH3COCH3/H2O (3:7, v:v) solution of CS1 gave a significantly quenched fluorescence.Other ions including Pb2+, Zn2+, Cu2+, Ca2+, Cd2+, Co2+, Mg2+, Mn2+, Hg2+, Ag+, Ni2+ induced no or much smaller spectral changes.This constitutes an ON–OFF Ag+-selective fluorescent chemosensor.
A novel chemosensor 1 (CS1) bearing one coumarin and two carbodithioate groups was synthesized and its fluorescent sensing behavior toward metal ions was investigated.Ag+ addition to a CH3COCH3/H2O (3:7, v:v) solution of CS1 gave a significantly quenched fluorescence.Other ions including Pb2+, Zn2+, Cu2+, Ca2+, Cd2+, Co2+, Mg2+, Mn2+, Hg2+, Ag+, Ni2+ induced no or much smaller spectral changes.This constitutes an ON–OFF Ag+-selective fluorescent chemosensor.
2008, 19(8): 981-984
doi: 10.1016/j.cclet.2008.05.021
Abstract:
A procedure for the simultaneous kinetic spectrophotometric determination of cephalexin and trimethoprim was described.It was based on the different reaction rate of oxidation of these compounds with yellow ammonium cerous (Ⅳ) sulfate in acidic medium and colorless cerous (Ⅲ) sulfate was produced.The overlapped kinetic data was quantitatively resolved by the use of chemometric methods, partial least squares (PLS), principal component regression (PCR) and radial basis function-artificial neural network (RBF-ANN).The proposed method was also applied to the simultaneous determination of cephalexin and trimethoprim in pharmaceutical preparation and human urine with satisfied results, which compared well with those obtained by HPLC.
A procedure for the simultaneous kinetic spectrophotometric determination of cephalexin and trimethoprim was described.It was based on the different reaction rate of oxidation of these compounds with yellow ammonium cerous (Ⅳ) sulfate in acidic medium and colorless cerous (Ⅲ) sulfate was produced.The overlapped kinetic data was quantitatively resolved by the use of chemometric methods, partial least squares (PLS), principal component regression (PCR) and radial basis function-artificial neural network (RBF-ANN).The proposed method was also applied to the simultaneous determination of cephalexin and trimethoprim in pharmaceutical preparation and human urine with satisfied results, which compared well with those obtained by HPLC.
2008, 19(8): 985-987
doi: 10.1016/j.cclet.2008.05.024
Abstract:
In this work, a new microextraction method termed ionic liquid based dispersive liquid-liquid microextraction (IL-DLLME) was demonstrated for the extraction of 2-methylaniline, 4-chloroaniline, 1-naphthylamine and 4-aminobiphenyl in aqueous matrices.After extraction the ionic liquid (IL) phase was injected directly into the high performance liquid chromatography (HPLC) system for determination.Some parameters that might affect the extraction efficiency were optimized.Under the optimum conditions, good linear relationship, sensitivity and reproducibility were obtained.The limits of detection (LOD, S/N=3) for the four analytes were in the range of 0.45-2.6 μg L-1.The relative standard deviations (R.S.D., n=6) were in the range of 6.2-9.8%.This method was applied for the analysis of the real water samples.The recoveries ranged from 93.4 to 106.4%.The main advantages of the method are high speed, high recovery, good repeatability and volatile organic solvent-free.
In this work, a new microextraction method termed ionic liquid based dispersive liquid-liquid microextraction (IL-DLLME) was demonstrated for the extraction of 2-methylaniline, 4-chloroaniline, 1-naphthylamine and 4-aminobiphenyl in aqueous matrices.After extraction the ionic liquid (IL) phase was injected directly into the high performance liquid chromatography (HPLC) system for determination.Some parameters that might affect the extraction efficiency were optimized.Under the optimum conditions, good linear relationship, sensitivity and reproducibility were obtained.The limits of detection (LOD, S/N=3) for the four analytes were in the range of 0.45-2.6 μg L-1.The relative standard deviations (R.S.D., n=6) were in the range of 6.2-9.8%.This method was applied for the analysis of the real water samples.The recoveries ranged from 93.4 to 106.4%.The main advantages of the method are high speed, high recovery, good repeatability and volatile organic solvent-free.
2008, 19(8): 988-991
doi: 10.1016/j.cclet.2008.04.024
Abstract:
Surface-attached micropatterned polyelectrolyte brushes on planar solid surfaces are generated using free radical polymerization photo-initiated by self-assembled initiator monolayers.It is shown that the formed patterns can be either negative or positive with different patterning processes.
Surface-attached micropatterned polyelectrolyte brushes on planar solid surfaces are generated using free radical polymerization photo-initiated by self-assembled initiator monolayers.It is shown that the formed patterns can be either negative or positive with different patterning processes.
2008, 19(8): 992-995
doi: 10.1016/j.cclet.2008.05.028
Abstract:
Environment friendly thermosetting composites were prepared by blending wheat gluten (WG) as matrix, calcium carbonate (CaCO3) as filler and glycerol as plasticizer followed by compression molding the mixture at 120 8C to crosslink the WG matrix.Morphology observation showed that the CaCO3 particles were finely dispersed in matrix.Incorporation of CaCO3 up to 10 wt% into the composites caused Young's modulus and tensile strength to increase markedly.On the other hand, the moisture absorption and elongation at break decreased slightly.
Environment friendly thermosetting composites were prepared by blending wheat gluten (WG) as matrix, calcium carbonate (CaCO3) as filler and glycerol as plasticizer followed by compression molding the mixture at 120 8C to crosslink the WG matrix.Morphology observation showed that the CaCO3 particles were finely dispersed in matrix.Incorporation of CaCO3 up to 10 wt% into the composites caused Young's modulus and tensile strength to increase markedly.On the other hand, the moisture absorption and elongation at break decreased slightly.
2008, 19(8): 996-999
doi: 10.1016/j.cclet.2008.05.026
Abstract:
In this paper, a novel SPME mode, PDMS-coated solid glass microspheres (SGMs), were prepared by sol-gel method.Using homemade thermal desorption unit coupled with CGC-FID, six PAHs as model analytes, the performance of the new mode was characterized.The new extractive phase exhibited high thermal stability and satisfactory extraction capability.The detection limits were 0.01-0.045 ng/mL, and the linearity was from 0.5 ng/mL to 96 ng/mL.The R.S.D.s of repeatability for retention time and peak area were all within 0.074% and 6.7%, respectively.The recoveries of the PAHs were 78-127% from the sarnples taken from river water.
In this paper, a novel SPME mode, PDMS-coated solid glass microspheres (SGMs), were prepared by sol-gel method.Using homemade thermal desorption unit coupled with CGC-FID, six PAHs as model analytes, the performance of the new mode was characterized.The new extractive phase exhibited high thermal stability and satisfactory extraction capability.The detection limits were 0.01-0.045 ng/mL, and the linearity was from 0.5 ng/mL to 96 ng/mL.The R.S.D.s of repeatability for retention time and peak area were all within 0.074% and 6.7%, respectively.The recoveries of the PAHs were 78-127% from the sarnples taken from river water.
2008, 19(8): 1000-1003
doi: 10.1016/j.cclet.2008.05.025
Abstract:
The roducfive demetalafion of manganese corroles was investigated in CH2Cl2/HCl (aqueous) solvent by using SnCl2 as reducing agent.It was found that the demetalation yields depend on the substituents of corrole macrocycle significantly.Electronrich manganese corrole undergoes reductive demetalation more easily than electron-deficient ones.The isolated reductive demetalation yield of manganese 5,10,15-tris(phenyl)corrole in present system is moderate (46%).As for electron-deficient Mn(III) 5,10,15-tris(pentafluorophenyl)corrole, the acid-induced demetalation in HOAc-H2SO4 (V/V=3:1) is preferable with an isolated yield of 67%.
The roducfive demetalafion of manganese corroles was investigated in CH2Cl2/HCl (aqueous) solvent by using SnCl2 as reducing agent.It was found that the demetalation yields depend on the substituents of corrole macrocycle significantly.Electronrich manganese corrole undergoes reductive demetalation more easily than electron-deficient ones.The isolated reductive demetalation yield of manganese 5,10,15-tris(phenyl)corrole in present system is moderate (46%).As for electron-deficient Mn(III) 5,10,15-tris(pentafluorophenyl)corrole, the acid-induced demetalation in HOAc-H2SO4 (V/V=3:1) is preferable with an isolated yield of 67%.
2008, 19(8): 1004-1007
doi: 10.1016/j.cclet.2008.05.013
Abstract:
The screen-printed nanoporous TiO2 thin film was employed to fabricate dye-sensitized solid-state solar cells using CuI as hole-transport materials.The solar cell based on nanoporous TiO2 thin film with large pores formed by the addition of polystyrene balls with diameter of 200 nm to the TiO2 paste exhibits photovoltaic performance enhancement, which is attributed to the good contact of CuI with surface of dye-sensitized thin film due to easy penetration of CuI in the film withlarge pores.
The screen-printed nanoporous TiO2 thin film was employed to fabricate dye-sensitized solid-state solar cells using CuI as hole-transport materials.The solar cell based on nanoporous TiO2 thin film with large pores formed by the addition of polystyrene balls with diameter of 200 nm to the TiO2 paste exhibits photovoltaic performance enhancement, which is attributed to the good contact of CuI with surface of dye-sensitized thin film due to easy penetration of CuI in the film withlarge pores.
2008, 19(8): 1008-1011
doi: 10.1016/j.cclet.2008.05.029
Abstract:
Two possible reaction mechanisms of VS+(3Σ-, 1Γ) with CO in the gas phase have been studied by using B3LYP/TZVP and CCSD(T)/6-311+G (3df, 3pd) methods:the O/S exchange reaction (VS++CO→VO++CS) and the S-transfer reaction (VS++CO→V++COS).The two reactions proceed via two-step and one-step mechanism, respectively.The barriers of the triplet and singlet PESs are 30.6 and 50.9 kcal/mol, respectively, for O/S exchange reaction and 7.3 and 50.2 kcal/mol, respectively, for the S-transfer reaction.The results indicate that the triplet ground state reaction is more favorable, and the S-transfer reaction is more favorable than the O/S exchange reaction, which is in good agreement with the experimental observation.
Two possible reaction mechanisms of VS+(3Σ-, 1Γ) with CO in the gas phase have been studied by using B3LYP/TZVP and CCSD(T)/6-311+G (3df, 3pd) methods:the O/S exchange reaction (VS++CO→VO++CS) and the S-transfer reaction (VS++CO→V++COS).The two reactions proceed via two-step and one-step mechanism, respectively.The barriers of the triplet and singlet PESs are 30.6 and 50.9 kcal/mol, respectively, for O/S exchange reaction and 7.3 and 50.2 kcal/mol, respectively, for the S-transfer reaction.The results indicate that the triplet ground state reaction is more favorable, and the S-transfer reaction is more favorable than the O/S exchange reaction, which is in good agreement with the experimental observation.
