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2010 Volume 21 Issue 3
2010, 21(3): 253-256
doi: 10.1016/j.cclet.2009.11.014
Abstract:
An efficient stereoselective synthesis of the rigid aza-bicyclo[3.2.0]heptane scaffold has been developed to provide 2-cyano-pyrrolidine alpha-amino amide 1 as DPP-4 inhibitor.
An efficient stereoselective synthesis of the rigid aza-bicyclo[3.2.0]heptane scaffold has been developed to provide 2-cyano-pyrrolidine alpha-amino amide 1 as DPP-4 inhibitor.
2010, 21(3): 257-260
doi: 10.1016/j.cclet.2009.11.023
Abstract:
A series of novel 4"-O-carbamoyl analogs of clarithromycin were synthesized and evaluated for their in vitro antibacterial activity. All of the desired compounds showed excellent activity against erythromycin-snsceptible S. pneumoniae, Particularly, 4-fluorobenzyl carbamate 7a demonstrated potent activity against erythromycin-resistant S. pneumoniae encoded by the mef gene, and remarkably improved activity against erythromycin-resistant S. pneumoniae encoded by the erm gene, and the erm and mef genes.
A series of novel 4"-O-carbamoyl analogs of clarithromycin were synthesized and evaluated for their in vitro antibacterial activity. All of the desired compounds showed excellent activity against erythromycin-snsceptible S. pneumoniae, Particularly, 4-fluorobenzyl carbamate 7a demonstrated potent activity against erythromycin-resistant S. pneumoniae encoded by the mef gene, and remarkably improved activity against erythromycin-resistant S. pneumoniae encoded by the erm gene, and the erm and mef genes.
2010, 21(3): 261-264
doi: 10.1016/j.cclet.2009.11.009
Abstract:
An acid catalyzed oxa-Pictet-Spengler reaction ‘on water’ leading to the synthesis of a variety of 1-aryl-6,7-dimethoxyisochro-mans is described. The aqueous chemistry is a much cleaner, efficient, cheaper and simple method for synthesis. The scope of reactions was extended to thia-Pictet-Spengler reaction to afford the some isothiochromans.
An acid catalyzed oxa-Pictet-Spengler reaction ‘on water’ leading to the synthesis of a variety of 1-aryl-6,7-dimethoxyisochro-mans is described. The aqueous chemistry is a much cleaner, efficient, cheaper and simple method for synthesis. The scope of reactions was extended to thia-Pictet-Spengler reaction to afford the some isothiochromans.
2010, 21(3): 265-268
doi: 10.1016/j.cclet.2009.11.016
Abstract:
An efficient synthesis of tetrahydroquinoline derivatives is reported via three component coupling reactions of aldehydes and anilines with various dienophiles in the presence of a catalytic amount of perchloric acid adsorbed on silica gel (HClO4-SiO2) under mild reaction conditions.
An efficient synthesis of tetrahydroquinoline derivatives is reported via three component coupling reactions of aldehydes and anilines with various dienophiles in the presence of a catalytic amount of perchloric acid adsorbed on silica gel (HClO4-SiO2) under mild reaction conditions.
2010, 21(3): 269-272
doi: 10.1016/j.cclet.2009.11.003
Abstract:
4,6-Diarylpyrimidin-2(1H)-one derivatives have been synthesized from three-component one-pot condensation of acetophe-none derivatives, aldehydes and urea in the presence of trimethylsilyl chloride and a catalytic amount of H3PMo12O40 under solvent-free conditions.
4,6-Diarylpyrimidin-2(1H)-one derivatives have been synthesized from three-component one-pot condensation of acetophe-none derivatives, aldehydes and urea in the presence of trimethylsilyl chloride and a catalytic amount of H3PMo12O40 under solvent-free conditions.
2010, 21(3): 273-276
doi: 10.1016/j.cclet.2009.11.049
Abstract:
Simple organic nitrogen bases, such as Et3N, pyridine, DBU, etc., were found to be convenient and useful reagents for deprotection of TBDMS groups on acidic hydroxyl groups. The efficiency of these bases has an apparent order: 1°amine > 2°amine > 3°amine and aliphatic base>aromatic base. In aqueous DMSO and at room temperature, phenolic TBDMS ethers were removed selectively in the presence of alcoholic TBDMS ethers. And catalytic base can make these reactions complete. This method is high-yielding, fast, clean, safe and cost-effective.
Simple organic nitrogen bases, such as Et3N, pyridine, DBU, etc., were found to be convenient and useful reagents for deprotection of TBDMS groups on acidic hydroxyl groups. The efficiency of these bases has an apparent order: 1°amine > 2°amine > 3°amine and aliphatic base>aromatic base. In aqueous DMSO and at room temperature, phenolic TBDMS ethers were removed selectively in the presence of alcoholic TBDMS ethers. And catalytic base can make these reactions complete. This method is high-yielding, fast, clean, safe and cost-effective.
2010, 21(3): 277-278
doi: 10.1016/j.cclet.2009.11.004
Abstract:
A new kind of aromatic diamine monomer containing pyridine unit, 2,6-bis[4-(4-aminophenoxy)phenoxy]pyridine (BAPP), was synthesized in three steps, using hydroquinone as starting material. A novel pyridine-containing polyimide was prepared from the resulting diamine BAPP with 4,4'-oxydiphthalic anhydride (ODPA) via a conventional two-step thermal imidization method. The resulting polyimide exhibits excellent solubility, film-forming capability and high thermal resistance.
A new kind of aromatic diamine monomer containing pyridine unit, 2,6-bis[4-(4-aminophenoxy)phenoxy]pyridine (BAPP), was synthesized in three steps, using hydroquinone as starting material. A novel pyridine-containing polyimide was prepared from the resulting diamine BAPP with 4,4'-oxydiphthalic anhydride (ODPA) via a conventional two-step thermal imidization method. The resulting polyimide exhibits excellent solubility, film-forming capability and high thermal resistance.
2010, 21(3): 279-282
doi: 10.1016/j.cclet.2009.11.005
Abstract:
A (polymer network/liquid crystal/chiral dopants) composite exhibiting a temperature-sensing switch of infrared spectrum has been developed. Because of the different change of the chiral dopant in the helical twisting power and the anchoring effect of the polymer network, the polymer stabilized liquid crystal (PSLC) films, of which the bandwidth of the selective reflection spectra increased with changing temperature, were obtained.
A (polymer network/liquid crystal/chiral dopants) composite exhibiting a temperature-sensing switch of infrared spectrum has been developed. Because of the different change of the chiral dopant in the helical twisting power and the anchoring effect of the polymer network, the polymer stabilized liquid crystal (PSLC) films, of which the bandwidth of the selective reflection spectra increased with changing temperature, were obtained.
2010, 21(3): 283-286
doi: 10.1016/j.cclet.2009.11.007
Abstract:
Eleven new imine derivatives 6 containing 1H-1,2,4-triazole and thiazole rings were synthesized by the condensation of 5-((1H-1,2,4-triazol-1-yl)methyl)-4-tert-butylthiazol-2-amine with various substituted benzaldehydes. The structures of the title com-pounds were characterized by 1H NMR, MS and elemental analysis. The plant-growth regulatory activities of these compounds were evaluated. The primary bioassay results indicated that these target compounds exhibited promising plant-growth regulatory activities.
Eleven new imine derivatives 6 containing 1H-1,2,4-triazole and thiazole rings were synthesized by the condensation of 5-((1H-1,2,4-triazol-1-yl)methyl)-4-tert-butylthiazol-2-amine with various substituted benzaldehydes. The structures of the title com-pounds were characterized by 1H NMR, MS and elemental analysis. The plant-growth regulatory activities of these compounds were evaluated. The primary bioassay results indicated that these target compounds exhibited promising plant-growth regulatory activities.
2010, 21(3): 287-289
doi: 10.1016/j.cclet.2009.11.030
Abstract:
A convenient approach for the preparation of sarpogrelate hydrochloride was developed. Two series of sarpogrelate hydrochloride analogues were designed and synthesized in order to improve their platelet aggregation inhibitory activities, biological tests suggested that these compounds have platelet aggregation inhibitory activities to some extent.
A convenient approach for the preparation of sarpogrelate hydrochloride was developed. Two series of sarpogrelate hydrochloride analogues were designed and synthesized in order to improve their platelet aggregation inhibitory activities, biological tests suggested that these compounds have platelet aggregation inhibitory activities to some extent.
2010, 21(3): 290-292
doi: 10.1016/j.cclet.2009.10.010
Abstract:
Four novel 5-substituted pyridine-2(1H)-one derivatives were designed and synthesized by using addition-elimination reactions. The structures of these novelly synthesized compounds were verified by 1H NMR, ESI-MS and single crystal X-ray diffraction. Furthermore, all four compounds (most notably compound 7a) were found to be highly efficient against hepatitis B virus (HBV) in cultured HepG22.2.15 cell, making them promising drug candidates for potential bioactive molecule against hepatitis B.
Four novel 5-substituted pyridine-2(1H)-one derivatives were designed and synthesized by using addition-elimination reactions. The structures of these novelly synthesized compounds were verified by 1H NMR, ESI-MS and single crystal X-ray diffraction. Furthermore, all four compounds (most notably compound 7a) were found to be highly efficient against hepatitis B virus (HBV) in cultured HepG22.2.15 cell, making them promising drug candidates for potential bioactive molecule against hepatitis B.
2010, 21(3): 293-296
doi: 10.1016/j.cclet.2009.11.008
Abstract:
A novel series of 3,6-disubstituted 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles were synthesized by the condensation of 4-amino-5-[2-(4-chlorophenoxymethylbenzimidazole)-1-methylene]-3-mercapto-1,2,4-triazole with various (un)substituted aromatic acids in the presence of phosphorous oxychloride. These compounds were investigated for their inhibitory activity to E. coli methionine aminopeptidase (EcMetAP1). Some of the tested compounds showed significant inhibitory activity.
A novel series of 3,6-disubstituted 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles were synthesized by the condensation of 4-amino-5-[2-(4-chlorophenoxymethylbenzimidazole)-1-methylene]-3-mercapto-1,2,4-triazole with various (un)substituted aromatic acids in the presence of phosphorous oxychloride. These compounds were investigated for their inhibitory activity to E. coli methionine aminopeptidase (EcMetAP1). Some of the tested compounds showed significant inhibitory activity.
2010, 21(3): 297-300
doi: 10.1016/j.cclet.2009.11.029
Abstract:
A series of novel 7'-azaindiruubin (1a-g) and 7-azaindirubin (2a, 2c, 2e and 2f) derivatives were designed and synthesized. Their structures were characterized by 1H NMR and MS spectroscopy as well as by elemental analysis. Their inhibitory properties against CDK2/cylinA were evaluated in vitro. In contrast to indirubin, some of the described azaindimbins emerged as potent inhibitors of CDK2/cylinA and compound 2b had more potent activity. Biological tests also showed that nitrogen atom at 7-position of azaindirubin was more beneficial to enhance the kinase inhibitory activity.
A series of novel 7'-azaindiruubin (1a-g) and 7-azaindirubin (2a, 2c, 2e and 2f) derivatives were designed and synthesized. Their structures were characterized by 1H NMR and MS spectroscopy as well as by elemental analysis. Their inhibitory properties against CDK2/cylinA were evaluated in vitro. In contrast to indirubin, some of the described azaindimbins emerged as potent inhibitors of CDK2/cylinA and compound 2b had more potent activity. Biological tests also showed that nitrogen atom at 7-position of azaindirubin was more beneficial to enhance the kinase inhibitory activity.
2010, 21(3): 301-304
doi: 10.1016/j.cclet.2009.11.045
Abstract:
An environmental benign procedure for synthesis of 2-(N-formyl)-5-aryl/aryloxymethyl-1,3,4-thiadiazoles has been developed by reaction of 2-amino-5-aryl/aryloxymethyl-1,3,4-thiadiazoles with formic acid in PEG-400. The key advantages of this protocol are the shorter reaction time, higher yields, lower cost, simple workup, and environment-friendly compared to conventional organic solvent reaction. The present method does not involve any hazardous organic solvent or catalyst.
An environmental benign procedure for synthesis of 2-(N-formyl)-5-aryl/aryloxymethyl-1,3,4-thiadiazoles has been developed by reaction of 2-amino-5-aryl/aryloxymethyl-1,3,4-thiadiazoles with formic acid in PEG-400. The key advantages of this protocol are the shorter reaction time, higher yields, lower cost, simple workup, and environment-friendly compared to conventional organic solvent reaction. The present method does not involve any hazardous organic solvent or catalyst.
2010, 21(3): 305-308
doi: 10.1016/j.cclet.2009.11.019
Abstract:
The enantioselective reduction of acetophenone analogues catalyzed by carrot and celeriac was performed in moderate conversions and excellent enantiomeric excesses. The steric factors and electronic effects of the substituents at the aromatic ring were found to significantly affect the efficiency of the enantioselective reduction of acetophenone analogues, while they had a little effect on the enantioselectivity of aeetophenone analogues reduction. It was also found that the conversions of acetophenone analogues reduction at 33℃ by means of both biocatalysts were three times as great as those at room temperature.
The enantioselective reduction of acetophenone analogues catalyzed by carrot and celeriac was performed in moderate conversions and excellent enantiomeric excesses. The steric factors and electronic effects of the substituents at the aromatic ring were found to significantly affect the efficiency of the enantioselective reduction of acetophenone analogues, while they had a little effect on the enantioselectivity of aeetophenone analogues reduction. It was also found that the conversions of acetophenone analogues reduction at 33℃ by means of both biocatalysts were three times as great as those at room temperature.
2010, 21(3): 309-311
doi: 10.1016/j.cclet.2009.11.046
Abstract:
A highly effective, new chiral 1,2,3,4-tetrahydroisoquinoline catalyst 1 for the diethylzinc addition to aryl aldehydes has been investigated. Using 10 mo1% of this chiral catalyst, secondary alcohols can be obtained in up to 87% yield and 99.5% ee under mild conditions.
A highly effective, new chiral 1,2,3,4-tetrahydroisoquinoline catalyst 1 for the diethylzinc addition to aryl aldehydes has been investigated. Using 10 mo1% of this chiral catalyst, secondary alcohols can be obtained in up to 87% yield and 99.5% ee under mild conditions.
2010, 21(3): 312-316
doi: 10.1016/j.cclet.2009.11.040
Abstract:
A highly efficient and regio-/stereoselective method of hydrosilylating terminal alkynes was developed using Pt(DVDS)-tri(t-butyl)phosphine catalyst system at room temperature. Trans-products or alpha-products were obtained almost exclusively depending on the alkynes and silanes employed.
A highly efficient and regio-/stereoselective method of hydrosilylating terminal alkynes was developed using Pt(DVDS)-tri(t-butyl)phosphine catalyst system at room temperature. Trans-products or alpha-products were obtained almost exclusively depending on the alkynes and silanes employed.
2010, 21(3): 317-321
doi: 10.1016/j.cclet.2009.11.001
Abstract:
Two new taraxastane-type triterpenoids, 20-taraxastene-3β,12β,16β-triol 1 and 3β-feruloyloxy-20-taraxastene-16β,28-diol 2, were isolated from the fruit of Cicuta virosa L. var latisecta Celak. There structures were ducidated by ESI-MS, 1D-and 2D-NMR spectroscopic methods.
Two new taraxastane-type triterpenoids, 20-taraxastene-3β,12β,16β-triol 1 and 3β-feruloyloxy-20-taraxastene-16β,28-diol 2, were isolated from the fruit of Cicuta virosa L. var latisecta Celak. There structures were ducidated by ESI-MS, 1D-and 2D-NMR spectroscopic methods.
2010, 21(3): 322-324
doi: 10.1016/j.cclet.2009.11.037
Abstract:
A new 5-O-(β-D-glucopyranosyl)-6'-O-benzoyl-2,5-dihydroxybenzoic acid was isolated from the ethyl acetate extract from the whole plants of Trifolium lupinaster L. Its structure was determined and deduced on the basis of their spectral data.
A new 5-O-(β-D-glucopyranosyl)-6'-O-benzoyl-2,5-dihydroxybenzoic acid was isolated from the ethyl acetate extract from the whole plants of Trifolium lupinaster L. Its structure was determined and deduced on the basis of their spectral data.
2010, 21(3): 325-328
doi: 10.1016/j.cclet.2009.11.006
Abstract:
Three new monophenanthrene compounds were isolated from an acetone extract of the tubers of Monomeria barbata Lindl. (Orchidaceae). Using spectroscopic methods, the structures of compounds 1-3 were determined as 1,4,7-trihydroxy-2-methoxy-9,10-dihydrophenanthrene (1), 1-(p-hydroxybenzoyl)-2-methoxy-4,7-dihydroxy-9,10-dihydrophenunthrene (2), 1,3,8-tri(p-hydroxybenzyl)-4-methoxy-phenanthrene-4,7-diol (3). These compounds showed cytotoxicities on four tumor cell lines (HepG2, HL-60, Skov-3, A431).
Three new monophenanthrene compounds were isolated from an acetone extract of the tubers of Monomeria barbata Lindl. (Orchidaceae). Using spectroscopic methods, the structures of compounds 1-3 were determined as 1,4,7-trihydroxy-2-methoxy-9,10-dihydrophenanthrene (1), 1-(p-hydroxybenzoyl)-2-methoxy-4,7-dihydroxy-9,10-dihydrophenunthrene (2), 1,3,8-tri(p-hydroxybenzyl)-4-methoxy-phenanthrene-4,7-diol (3). These compounds showed cytotoxicities on four tumor cell lines (HepG2, HL-60, Skov-3, A431).
2010, 21(3): 329-331
doi: 10.1016/j.cclet.2009.11.036
Abstract:
2-[3,5-Di-O-β-D-glucosyl-4-(3-methylbut-2-enyl)phenyl]benzofuran-6-ol, a new prenylated arylbenzofuran derivative was isolated from Morus alba L. Its structure was elucidated by various spectroscopic methods including MS, 1H NMR, 13C NMR, DEPT, 1H-1HCOSY, HMQC and HMBC.
2-[3,5-Di-O-β-D-glucosyl-4-(3-methylbut-2-enyl)phenyl]benzofuran-6-ol, a new prenylated arylbenzofuran derivative was isolated from Morus alba L. Its structure was elucidated by various spectroscopic methods including MS, 1H NMR, 13C NMR, DEPT, 1H-1HCOSY, HMQC and HMBC.
2010, 21(3): 332-336
doi: 10.1016/j.cclet.2009.11.015
Abstract:
A unusual flavone glycoside named Shamimarin (1) and a new compound Acetoxy-8-methyl-chromen-2H-one (2) were isolated from aerial parts of Rhododendron lepidotum L. Along with four known coumarins daphnin (3), daphnetin 8-O-β-D-glucopyrano-side (4), daphnetin (5) and umbelliferone (6). The structural elucidations were based on analyses of chemical and spectroscopic data by including ID and 2D NMR analyses.
A unusual flavone glycoside named Shamimarin (1) and a new compound Acetoxy-8-methyl-chromen-2H-one (2) were isolated from aerial parts of Rhododendron lepidotum L. Along with four known coumarins daphnin (3), daphnetin 8-O-β-D-glucopyrano-side (4), daphnetin (5) and umbelliferone (6). The structural elucidations were based on analyses of chemical and spectroscopic data by including ID and 2D NMR analyses.
2010, 21(3): 337-340
doi: 10.1016/j.cclet.2009.11.048
Abstract:
The electrocatalytic oxidation of methanol at the platinum electrode modified with Eu-Fe cyanide-bridged binuclear complexes (Eu-Fe film) was investigated for the first time by cyclic voltammetry. Compared with the bare platinum electrode, the results showed that the modified electrode had excellent electrocatalytic activity for the oxidation of methanol; the oxidation peak potential shifted more negatively and the peak current increased about twenty times. The electrooxidation of methanol at the modified electrode with Eu-Fe cyanide-bridged binuclear complexes material exhibited the better tolerance capacity to poison of intermediate species; the peak current was proportional to the concentration of methanol in the range of 0.5-2.0 mol/L (R2=0.9991, n=7), which was a comparatively wider linear range. Moreover, based on the linear relationship between the peak current and the square root of scan rate, electrocatalytic oxidation process of methanol was confirmed to be a diffusion control process. Furthermore, according to the counting of electron transfer number (nα) in the rate-limiting step and the slope of linear equation between acidity of electrolyte and the oxidation peak potential (Ep), the possible mechanism of the electrooxidation of methanol at the modified electrode was primarily discussed.
The electrocatalytic oxidation of methanol at the platinum electrode modified with Eu-Fe cyanide-bridged binuclear complexes (Eu-Fe film) was investigated for the first time by cyclic voltammetry. Compared with the bare platinum electrode, the results showed that the modified electrode had excellent electrocatalytic activity for the oxidation of methanol; the oxidation peak potential shifted more negatively and the peak current increased about twenty times. The electrooxidation of methanol at the modified electrode with Eu-Fe cyanide-bridged binuclear complexes material exhibited the better tolerance capacity to poison of intermediate species; the peak current was proportional to the concentration of methanol in the range of 0.5-2.0 mol/L (R2=0.9991, n=7), which was a comparatively wider linear range. Moreover, based on the linear relationship between the peak current and the square root of scan rate, electrocatalytic oxidation process of methanol was confirmed to be a diffusion control process. Furthermore, according to the counting of electron transfer number (nα) in the rate-limiting step and the slope of linear equation between acidity of electrolyte and the oxidation peak potential (Ep), the possible mechanism of the electrooxidation of methanol at the modified electrode was primarily discussed.
2010, 21(3): 341-345
doi: 10.1016/j.cclet.2009.10.026
Abstract:
The kinetics of dissolved O2 reduction and hydrogen evolution reactions on copper surface was studied in naturally aerated and air and O2-saturated 0.50 mol/L H2SO4 solutions using polarization measurements combined with the rotating disc electrode (RDE). The Koutecky-Levich plot indicated that the dissolved O2 reduction at the copper electrode was an apparent four-electron process. A correlation between the presence of dissolved O2 and the formation of Cu2O, confirmed from XRD, was discussed. Ascorbic acid (AA) was tested as a safe inhibitor for copper corrosion in H2SO4 solutions at 25℃. Measurements were carried out as a function of dissolved oxygen concentration using Tafel polarization measurements. The addition of AA slowed down the reduction reaction of dissolved O2 more effectively than the anodic reaction. Dissolved O2 was found to enhance the inhibition performance of AA. Adsorption via hydrogen bonding was considered.
The kinetics of dissolved O2 reduction and hydrogen evolution reactions on copper surface was studied in naturally aerated and air and O2-saturated 0.50 mol/L H2SO4 solutions using polarization measurements combined with the rotating disc electrode (RDE). The Koutecky-Levich plot indicated that the dissolved O2 reduction at the copper electrode was an apparent four-electron process. A correlation between the presence of dissolved O2 and the formation of Cu2O, confirmed from XRD, was discussed. Ascorbic acid (AA) was tested as a safe inhibitor for copper corrosion in H2SO4 solutions at 25℃. Measurements were carried out as a function of dissolved oxygen concentration using Tafel polarization measurements. The addition of AA slowed down the reduction reaction of dissolved O2 more effectively than the anodic reaction. Dissolved O2 was found to enhance the inhibition performance of AA. Adsorption via hydrogen bonding was considered.
2010, 21(3): 346-348
doi: 10.1016/j.cclet.2009.11.043
Abstract:
The determination method of catechol by fluorescence quenching was developed. The assay was based on the combination of the unique property of gold nanoparticles with tyrosinase enzymatic reaction. In the presence of tyrosinase, the fluorescence of gold nanoparticles was quenched by catechol which can be employed to detect catechol. Under the optimal conditions, a linear range 5.0×10-7-1.0×10-3 mol L-1 and a detection limit 1.0×10-7 mol L-1 of catechol were obtained, o-Quinone intermediate produced from the enzymatic catalyzed oxidation of catechol was considered to play the main role in the fluorescence quenching.
The determination method of catechol by fluorescence quenching was developed. The assay was based on the combination of the unique property of gold nanoparticles with tyrosinase enzymatic reaction. In the presence of tyrosinase, the fluorescence of gold nanoparticles was quenched by catechol which can be employed to detect catechol. Under the optimal conditions, a linear range 5.0×10-7-1.0×10-3 mol L-1 and a detection limit 1.0×10-7 mol L-1 of catechol were obtained, o-Quinone intermediate produced from the enzymatic catalyzed oxidation of catechol was considered to play the main role in the fluorescence quenching.
2010, 21(3): 349-352
doi: 10.1016/j.cclet.2009.10.008
Abstract:
The electrochemistry behavior of dopamine was investigated by cyclic voltammetry and differential pulse voltammetry at a poly (gallic acid) film modified glassy carbon electrode. Two electrons and two protons participated in the diffusion-controlled electrocatalytic oxidation of dopamine with a diffusion coefficient of 2.186×10-5 cm2/s. The interference of ascorbic acid with the determination of dopamine could be efficiently eliminated. This work provided a simple approach to selectively and sensitively detect dopamine in the presence of high concentration of ascorbic acid.
The electrochemistry behavior of dopamine was investigated by cyclic voltammetry and differential pulse voltammetry at a poly (gallic acid) film modified glassy carbon electrode. Two electrons and two protons participated in the diffusion-controlled electrocatalytic oxidation of dopamine with a diffusion coefficient of 2.186×10-5 cm2/s. The interference of ascorbic acid with the determination of dopamine could be efficiently eliminated. This work provided a simple approach to selectively and sensitively detect dopamine in the presence of high concentration of ascorbic acid.
2010, 21(3): 353-356
doi: 10.1016/j.cclet.2009.11.044
Abstract:
In this study, we have fabricated molecularly imprinted polypyrrole (PPy) packed electrode columns and investigated their effects on separation of tryptophan (Trp) enantiomers by using potential control. The results indicate that the imprinted PPy electrode columns could efficiently enhance the L-Trp uptake and separate Trp enantiomers effectively, implying the great potential for the enantioselective recognition of other amino acids enantiomers.
In this study, we have fabricated molecularly imprinted polypyrrole (PPy) packed electrode columns and investigated their effects on separation of tryptophan (Trp) enantiomers by using potential control. The results indicate that the imprinted PPy electrode columns could efficiently enhance the L-Trp uptake and separate Trp enantiomers effectively, implying the great potential for the enantioselective recognition of other amino acids enantiomers.
2010, 21(3): 357-360
doi: 10.1016/j.cclet.2009.10.015
Abstract:
Chelate tetra(acetylacetonato) tin (Ⅳ) was prepared and used as catalyst for polytrimethylene terephthalate synthesis. It exhibited higher catalytic activity than tetrabutyl titanate, butyltinhydroxide oxide and dibutyltin oxide. Decrease in reaction time, content of terminal carboxyl group, color intensity and increase in intrinsic viscosity were observed. The unique molecular structure can be considered as factor remarkably improving the catalytic activity of tetra(acetylacetonato) tin (Ⅳ).
Chelate tetra(acetylacetonato) tin (Ⅳ) was prepared and used as catalyst for polytrimethylene terephthalate synthesis. It exhibited higher catalytic activity than tetrabutyl titanate, butyltinhydroxide oxide and dibutyltin oxide. Decrease in reaction time, content of terminal carboxyl group, color intensity and increase in intrinsic viscosity were observed. The unique molecular structure can be considered as factor remarkably improving the catalytic activity of tetra(acetylacetonato) tin (Ⅳ).
2010, 21(3): 361-364
doi: 10.1016/j.cclet.2009.11.031
Abstract:
A novel star-comb polybutadiene (SC-PB) was synthesized with n-butyllithium (n-BuLi) as initiator, epoxidized star liquid polybutadiene (ESPB) as coupling agent, cyclohexane as solvent by living anionic polymerization and grafting-onto technology. The SC-PB was subsequently hydrogenated by homogeneous catalysis (catalytic hydrogenation using nickel naphthenate/ triisobutyl aluminum), to transform the SC-PB into the corresponding star-comb poly(ethylene-co-butene) (SC-PEB). The SC-PB was characterized by SEC-TALLS, 1H NMR, DSC and WAXD techniques. The hydrogenation degree and crystaninity degree of SC-PEB were also determined.
A novel star-comb polybutadiene (SC-PB) was synthesized with n-butyllithium (n-BuLi) as initiator, epoxidized star liquid polybutadiene (ESPB) as coupling agent, cyclohexane as solvent by living anionic polymerization and grafting-onto technology. The SC-PB was subsequently hydrogenated by homogeneous catalysis (catalytic hydrogenation using nickel naphthenate/ triisobutyl aluminum), to transform the SC-PB into the corresponding star-comb poly(ethylene-co-butene) (SC-PEB). The SC-PB was characterized by SEC-TALLS, 1H NMR, DSC and WAXD techniques. The hydrogenation degree and crystaninity degree of SC-PEB were also determined.
2010, 21(3): 365-368
doi: 10.1016/j.cclet.2009.11.020
Abstract:
Photoreaction of 9-vinylcarbazole in acetonitrile in the presence of titanium dioxide and a catalytic amount of magnesium perchlorate gave 3,6-di(9-carbazolyl)-1,2-dioxane as a photooxygenated product via photodimerization of 9-vinylcarbazole. The photoreaction proceeds via an electron transfer mechanism, where magnesium perchlorate accelerated formation of the photo-oxygenated product.
Photoreaction of 9-vinylcarbazole in acetonitrile in the presence of titanium dioxide and a catalytic amount of magnesium perchlorate gave 3,6-di(9-carbazolyl)-1,2-dioxane as a photooxygenated product via photodimerization of 9-vinylcarbazole. The photoreaction proceeds via an electron transfer mechanism, where magnesium perchlorate accelerated formation of the photo-oxygenated product.
2010, 21(3): 369-372
doi: 10.1016/j.cclet.2009.11.002
Abstract:
Dense ceramic membranes with protonic and electronic conductivity have attracted considerable interest in recent years. In this paper, the powders of SrCe0.75Zr0.20Tm0.05O3-δ were synthesized via the liquid citrate method, and the membranes of SrCe0.75Zr0.20Tm0.05O3-δ were prepared by pressing followed by sintering. X-ray diffraction (XRD) was used to characterize the phase structure of both the powder and sintered membrane. The microstructure of the sintered membranes was studied by scanning electron microscopy (SEM). Hydrogen permeation through the SrCe0.75Zr0.20Tm0.05O3-δ membranes was carried out using gas permeation setup at 900℃. Hydrogen permeation flux of SrCe0.75Zr0.20Tm0.05O3-δ membrane reaches up to 0.042 mL/ min cm2 at H2 partial pressure of 0.4 atm. The hydrogen permeation fluxes obtained in this paper are similar to that of SrCe0.75Tm0.05O3-δ and Zr doping can increase mechanical strength of SrCe0.75Zr0.20Tm0.05O3-δ membranes and the resistance to reducing circumstance.
Dense ceramic membranes with protonic and electronic conductivity have attracted considerable interest in recent years. In this paper, the powders of SrCe0.75Zr0.20Tm0.05O3-δ were synthesized via the liquid citrate method, and the membranes of SrCe0.75Zr0.20Tm0.05O3-δ were prepared by pressing followed by sintering. X-ray diffraction (XRD) was used to characterize the phase structure of both the powder and sintered membrane. The microstructure of the sintered membranes was studied by scanning electron microscopy (SEM). Hydrogen permeation through the SrCe0.75Zr0.20Tm0.05O3-δ membranes was carried out using gas permeation setup at 900℃. Hydrogen permeation flux of SrCe0.75Zr0.20Tm0.05O3-δ membrane reaches up to 0.042 mL/ min cm2 at H2 partial pressure of 0.4 atm. The hydrogen permeation fluxes obtained in this paper are similar to that of SrCe0.75Tm0.05O3-δ and Zr doping can increase mechanical strength of SrCe0.75Zr0.20Tm0.05O3-δ membranes and the resistance to reducing circumstance.
2010, 21(3): 373-375
doi: 10.1016/j.cclet.2009.11.027
Abstract:
DNA photocleavage properties of halogenated mono-hydroxyl corrole 1-5 were investigated. It was found that these corroles were able to photocleavage supercoiled pBR 322 DNA (SC) into nicked-circular DNA (NC). The activity of these corroles follows an order of 4 > 3 > 2≈ 1 > 5. The photosensitized singlet oxygen (φ△) quantum yield by these corroles also follows that same order, showing the photocleavage activity is related to the heavy atom effect of halogen atoms on corroles.
DNA photocleavage properties of halogenated mono-hydroxyl corrole 1-5 were investigated. It was found that these corroles were able to photocleavage supercoiled pBR 322 DNA (SC) into nicked-circular DNA (NC). The activity of these corroles follows an order of 4 > 3 > 2≈ 1 > 5. The photosensitized singlet oxygen (φ△) quantum yield by these corroles also follows that same order, showing the photocleavage activity is related to the heavy atom effect of halogen atoms on corroles.
2010, 21(3): 376-378
doi: 10.1016/j.cclet.2009.11.041
Abstract:
Quasi-classical trajectory (QCT) calculations have been carried out to study the generalized polarization dependent differential cross sections (PDDCSs) for the reactions H+LiH+(v=0,j=0)→H2+Li+ and H++LiH(v=0,j=0)→H2++Li occurring on the two lowest-lying electronic states of the LiH2+ system, using the ab initio potential energy surfaces (PESs) of Martinazzo et al. [3]. Four PDDCSs, i.e., (2π/σ)(dσ00/dωt), (2π/σ)(dσ20/doωt), (2π/σ)(dσ22+/dωt), (2π/σ)(dσ21-/dωt) have been discussed in detail.
Quasi-classical trajectory (QCT) calculations have been carried out to study the generalized polarization dependent differential cross sections (PDDCSs) for the reactions H+LiH+(v=0,j=0)→H2+Li+ and H++LiH(v=0,j=0)→H2++Li occurring on the two lowest-lying electronic states of the LiH2+ system, using the ab initio potential energy surfaces (PESs) of Martinazzo et al. [3]. Four PDDCSs, i.e., (2π/σ)(dσ00/dωt), (2π/σ)(dσ20/doωt), (2π/σ)(dσ22+/dωt), (2π/σ)(dσ21-/dωt) have been discussed in detail.
