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2009 Volume 20 Issue 2
2009, 20(2): 127-130
doi: 10.1016/j.cclet.2008.11.002
Abstract:
Highly efficient removal of allyloxycarbonyl (Alloc) group was achieved in the presence of CH3COONH4, Pd[P(C6H5)3]4, and NaBH4 in MeOH-THF, within 5 min in almost quantitative yields (>90%, isolated yield) without affecting acetyl, benzoyl, isopropylidene, benzylidene, allyl, benzyl, benzyl carbonate, or azido groups.
Highly efficient removal of allyloxycarbonyl (Alloc) group was achieved in the presence of CH3COONH4, Pd[P(C6H5)3]4, and NaBH4 in MeOH-THF, within 5 min in almost quantitative yields (>90%, isolated yield) without affecting acetyl, benzoyl, isopropylidene, benzylidene, allyl, benzyl, benzyl carbonate, or azido groups.
2009, 20(2): 131-135
doi: 10.1016/j.cclet.2008.10.038
Abstract:
The production of propylene carbonate (PC) from urea and 1,2-propanediol (PG) was investigated in a batch process. The catalytic performances of zinc chloride and magnesium chloride were investigated for this reaction system. The influences of various operation conditions on the PC yield were explored. In this work, MgCl2 and ZnCl2 showed the excellent catalytic activity toward PC synthesis, and the yields of propylene carbonate reached 96.5% and 92.4%, respectively. The optimum reaction conditions were as follows: ethanol/urea molar ratio of 4, catalyst concentration of 1.5%, reaction temperature of 160℃, reaction time of 3 h, respectively. The route from urea and 1,2-propanediol shows advantages, such as mild reaction condition and safe operation. The catalytic system is environmentally benign.
The production of propylene carbonate (PC) from urea and 1,2-propanediol (PG) was investigated in a batch process. The catalytic performances of zinc chloride and magnesium chloride were investigated for this reaction system. The influences of various operation conditions on the PC yield were explored. In this work, MgCl2 and ZnCl2 showed the excellent catalytic activity toward PC synthesis, and the yields of propylene carbonate reached 96.5% and 92.4%, respectively. The optimum reaction conditions were as follows: ethanol/urea molar ratio of 4, catalyst concentration of 1.5%, reaction temperature of 160℃, reaction time of 3 h, respectively. The route from urea and 1,2-propanediol shows advantages, such as mild reaction condition and safe operation. The catalytic system is environmentally benign.
2009, 20(2): 136-138
doi: 10.1016/j.cclet.2008.11.004
Abstract:
A series of hepatic targeting drugs, 5-Fu-cholic acid conjugate T1-T5, were synthesized. 5-Fu and cholic acid was selected as starting material, after N-hydroxymethylation, condensation, hydrogenolysis to obtain carboxylated 5-Fu 5a-e. Carboxylated 5-Fu 5a-e were condensated with intermediate 3-hydroxyethyl cholic acid benzyl ester 6 to get 7a-e, 7a-e were deprotected to get T1-T5.
A series of hepatic targeting drugs, 5-Fu-cholic acid conjugate T1-T5, were synthesized. 5-Fu and cholic acid was selected as starting material, after N-hydroxymethylation, condensation, hydrogenolysis to obtain carboxylated 5-Fu 5a-e. Carboxylated 5-Fu 5a-e were condensated with intermediate 3-hydroxyethyl cholic acid benzyl ester 6 to get 7a-e, 7a-e were deprotected to get T1-T5.
2009, 20(2): 139-142
doi: 10.1016/j.cclet.2008.10.037
Abstract:
A facile, efficient and substrate-selective oxidation of aldehydes to carboxylic acids with NaClO catalyzed by β-cyclodextrin in water has been developed. A series of aldehydes which could form inclusion complex with β-cyclodextrin (β-CD) were oxidized selectively with excellent yields.
A facile, efficient and substrate-selective oxidation of aldehydes to carboxylic acids with NaClO catalyzed by β-cyclodextrin in water has been developed. A series of aldehydes which could form inclusion complex with β-cyclodextrin (β-CD) were oxidized selectively with excellent yields.
2009, 20(2): 143-146
doi: 10.1016/j.cclet.2008.10.052
Abstract:
25,27-Dipropoxy-p-tert-butylcalix[4]crown-9 cone conformer 5 was readily synthesized via an intramolecular cyclization strategy in good yields. The structures of all the new compounds involved were confirmed by NMR, ESI-MS and elemental analyses. All of them were proved to be in the cone conformation.
25,27-Dipropoxy-p-tert-butylcalix[4]crown-9 cone conformer 5 was readily synthesized via an intramolecular cyclization strategy in good yields. The structures of all the new compounds involved were confirmed by NMR, ESI-MS and elemental analyses. All of them were proved to be in the cone conformation.
2009, 20(2): 147-149
doi: 10.1016/j.cclet.2008.10.034
Abstract:
Gibbilimbols B and D were synthesized from the facile rearrangement of sulfone in the presence of dibromodifluoromethane and alumina-supported KOH in dichloromethane, followed by refluxing the rearrangement products in conc. HCl and methanol and then treating with thiophenol in the presence of AIBN.
Gibbilimbols B and D were synthesized from the facile rearrangement of sulfone in the presence of dibromodifluoromethane and alumina-supported KOH in dichloromethane, followed by refluxing the rearrangement products in conc. HCl and methanol and then treating with thiophenol in the presence of AIBN.
2009, 20(2): 150-152
doi: 10.1016/j.cclet.2008.10.051
Abstract:
Biomimetic transformation of gentiopicroside was carried out by β-glucosidase at pH 7.0 for 3 days at 37℃. Two products,erythrocentaurin and 5,6-dihydro-5-formyl-6-methyl-1H,3H-pyrano[3,4-c]pyran-1-one were isolated and identified by 1H NMR,13C NMR, UV, IR, MS and elemental analyse. The possible mechanisms were discussed.
Biomimetic transformation of gentiopicroside was carried out by β-glucosidase at pH 7.0 for 3 days at 37℃. Two products,erythrocentaurin and 5,6-dihydro-5-formyl-6-methyl-1H,3H-pyrano[3,4-c]pyran-1-one were isolated and identified by 1H NMR,13C NMR, UV, IR, MS and elemental analyse. The possible mechanisms were discussed.
2009, 20(2): 153-157
doi: 10.1016/j.cclet.2008.10.049
Abstract:
Title compounds 2',2'-dimethylcholesta-2,4-dien[3,2-b]-pyran-4'-one (3), 2',2'-dimethyl-3β-substituted cholesta-4,6-dien[7,6-b]-pyran-4'-one (6a,b) and (6c) were prepared by the cyclization of 2-acetylcholesta-2,4-dien-3-ol (2), 6-acetyl-3β-substitutedcholesta-4,6-dien-7-ol (5a,b) and (5c) respectively, with pyrrolidine, dry benzene and dry acetone using Dean Stark separator through conventional heating. Furthermore, compounds were also found to be active against Mycobacterium tuberculosis.
Title compounds 2',2'-dimethylcholesta-2,4-dien[3,2-b]-pyran-4'-one (3), 2',2'-dimethyl-3β-substituted cholesta-4,6-dien[7,6-b]-pyran-4'-one (6a,b) and (6c) were prepared by the cyclization of 2-acetylcholesta-2,4-dien-3-ol (2), 6-acetyl-3β-substitutedcholesta-4,6-dien-7-ol (5a,b) and (5c) respectively, with pyrrolidine, dry benzene and dry acetone using Dean Stark separator through conventional heating. Furthermore, compounds were also found to be active against Mycobacterium tuberculosis.
2009, 20(2): 158-160
doi: 10.1016/j.cclet.2008.10.050
Abstract:
A rapid and heterogeneous Pd/C-catalyzed atom-efficient phenylation of aryl bromides by sodium tetraphenylborate takes place under focused microwave irradiation in water. The palladium catalyst can be easily recovered and reused.
A rapid and heterogeneous Pd/C-catalyzed atom-efficient phenylation of aryl bromides by sodium tetraphenylborate takes place under focused microwave irradiation in water. The palladium catalyst can be easily recovered and reused.
2009, 20(2): 161-164
doi: 10.1016/j.cclet.2008.10.048
Abstract:
Keggin type heteropolyacids was found to be an efficient and reusable catalyst for the synthesis of biologically active quinoxaline derivatives from the condensation of 1,2-diamine with 1,2-dicarbonyl compounds in excellent yields in water. This method provides a new and efficient protocol in terms of small quantity of catalyst, a wide scope of substrates, and simple work-up procedure.
Keggin type heteropolyacids was found to be an efficient and reusable catalyst for the synthesis of biologically active quinoxaline derivatives from the condensation of 1,2-diamine with 1,2-dicarbonyl compounds in excellent yields in water. This method provides a new and efficient protocol in terms of small quantity of catalyst, a wide scope of substrates, and simple work-up procedure.
2009, 20(2): 165-167
doi: 10.1016/j.cclet.2008.10.046
Abstract:
A novel Pd-catalyzed sequential reaction for the synthesis of fused tricyclic compounds with a dihydrofuran or isobenzofuranone unit was developed.
A novel Pd-catalyzed sequential reaction for the synthesis of fused tricyclic compounds with a dihydrofuran or isobenzofuranone unit was developed.
2009, 20(2): 168-170
doi: 10.1016/j.cclet.2008.10.029
Abstract:
A series of novel mono-and di-terpyridine derivatives with purinyl and pyrimidyl group were obtained from the reaction of 4'-pbromomethylphenyl-2,2':6,2"-terpyridine with 6-mercaptopurine, 2,6-dimercaptopurine and thymine, respectively. The active hydrogens on these alkaloids could be abstracted stepwise using different bases, which made the addition controllable.
A series of novel mono-and di-terpyridine derivatives with purinyl and pyrimidyl group were obtained from the reaction of 4'-pbromomethylphenyl-2,2':6,2"-terpyridine with 6-mercaptopurine, 2,6-dimercaptopurine and thymine, respectively. The active hydrogens on these alkaloids could be abstracted stepwise using different bases, which made the addition controllable.
2009, 20(2): 171-174
doi: 10.1016/j.cclet.2008.10.042
Abstract:
Oxalic acid has been used as a catalyst for intramolecular cyclisation of 2-hydroxychalcones to form flavones in good yields. The efficiency of the catalyst was proved with a variety of substrates ranging from electron-deficient to electron-rich aryl aldehydes and 2-hydroxychalcone.
Oxalic acid has been used as a catalyst for intramolecular cyclisation of 2-hydroxychalcones to form flavones in good yields. The efficiency of the catalyst was proved with a variety of substrates ranging from electron-deficient to electron-rich aryl aldehydes and 2-hydroxychalcone.
2009, 20(2): 175-177
doi: 10.1016/j.cclet.2008.11.003
Abstract:
In an attempt to search for more potent positive inotropic agents, a series of 1-(benzylamino)-3-(4,5-dihydro[1,2,4]trizaolo[4,3-a]quinolin-7-yloxy)propan-2-ol derivatives was synthesized in four steps using 6-hydroxy-3,4-dihydro-2(1H)-quinolinone as a starting material, and their positive inotropic activities were evaluated by measuring the coronary blood flow (CBF) and the left ventricular pressure (LVP) followed by calculating the rate of pressure development (dp/dtmax values) in the preparation of rat Langendorff's heart. Three compounds (5d, 5g, 5j) showed favorable activities, among which 5g was shown the most potent with dp/dtmax value of 9.7% and CBF value of 17.8% at a concentration of 1×10-5 mol/L in our in vitro study.
In an attempt to search for more potent positive inotropic agents, a series of 1-(benzylamino)-3-(4,5-dihydro[1,2,4]trizaolo[4,3-a]quinolin-7-yloxy)propan-2-ol derivatives was synthesized in four steps using 6-hydroxy-3,4-dihydro-2(1H)-quinolinone as a starting material, and their positive inotropic activities were evaluated by measuring the coronary blood flow (CBF) and the left ventricular pressure (LVP) followed by calculating the rate of pressure development (dp/dtmax values) in the preparation of rat Langendorff's heart. Three compounds (5d, 5g, 5j) showed favorable activities, among which 5g was shown the most potent with dp/dtmax value of 9.7% and CBF value of 17.8% at a concentration of 1×10-5 mol/L in our in vitro study.
2009, 20(2): 178-180
doi: 10.1016/j.cclet.2008.10.027
Abstract:
Seventeen 4-alkylamino/arylamino-substituted methotrexate (MTX) derivatives 6a-14a were designed and synthesized. Their inhibition activities against inducible nitric oxide synthase (iNOS) were evaluated in vitro. The pharmacological results showed that most of the prepared compounds displayed the potent inhibitory effects on iNOS.
Seventeen 4-alkylamino/arylamino-substituted methotrexate (MTX) derivatives 6a-14a were designed and synthesized. Their inhibition activities against inducible nitric oxide synthase (iNOS) were evaluated in vitro. The pharmacological results showed that most of the prepared compounds displayed the potent inhibitory effects on iNOS.
2009, 20(2): 181-183
doi: 10.1016/j.cclet.2008.10.035
Abstract:
A new aryl glycoside, 3"-O-galloyl-benzyl-O-a-L-rhamnopyranosyl-(1→6)-b-D-glucopyranoside, was isolated from Euphorbia helioscopia L., and its structure was elucidated on the basis of various spectroscopic data analysis.
A new aryl glycoside, 3"-O-galloyl-benzyl-O-a-L-rhamnopyranosyl-(1→6)-b-D-glucopyranoside, was isolated from Euphorbia helioscopia L., and its structure was elucidated on the basis of various spectroscopic data analysis.
2009, 20(2): 184-186
doi: 10.1016/j.cclet.2008.10.033
Abstract:
Two new methane-type monoterpene glycosides were isolated from the roots of Doellingeria scaber. Their structures were identified as trans-p-menthane-1a,2β,8-triol 8-O-β-D-(3',6'-diangeloyloxy)-glucopyranoside and trans-p-menthane-1a,2β,8-triol 8-O-β-D-(3'-angeloyloxy,6'-isobutyloxy)-glucopyranoside based on 1D and 2D NMR spectroscopy.
Two new methane-type monoterpene glycosides were isolated from the roots of Doellingeria scaber. Their structures were identified as trans-p-menthane-1a,2β,8-triol 8-O-β-D-(3',6'-diangeloyloxy)-glucopyranoside and trans-p-menthane-1a,2β,8-triol 8-O-β-D-(3'-angeloyloxy,6'-isobutyloxy)-glucopyranoside based on 1D and 2D NMR spectroscopy.
2009, 20(2): 187-189
doi: 10.1016/j.cclet.2008.10.032
Abstract:
A new depsidone, diffractione A (1), as well as six known phenolic compounds (2-7) were isolated from Usnea diffracta. Their structures were elucidated by 1D and 2D NMR spectroscopy together with HRESIMS analysis. All components were obtained for the first time from U. diffracta.
A new depsidone, diffractione A (1), as well as six known phenolic compounds (2-7) were isolated from Usnea diffracta. Their structures were elucidated by 1D and 2D NMR spectroscopy together with HRESIMS analysis. All components were obtained for the first time from U. diffracta.
2009, 20(2): 190-192
doi: 10.1016/j.cclet.2008.11.001
Abstract:
A new rearranged chamigrane sesquiterpene, named laurenokamurin, was isolated from the marine red alga Laurencia okamurai. Its structure was determined on the basis of spectroscopic methods.
A new rearranged chamigrane sesquiterpene, named laurenokamurin, was isolated from the marine red alga Laurencia okamurai. Its structure was determined on the basis of spectroscopic methods.
2009, 20(2): 193-196
doi: 10.1016/j.cclet.2008.10.030
Abstract:
A new triterpenoid saponin, 3-O-{β-D-xylopyranosyl-(1→2)-b-D-glucopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→2)]-a-L-arabinopyranosyl}-3β,16α,28α-trihydroxy-13β,28-epoxy-oleanan-30-al (ardipusilloside Ⅲ, 1), together with two known saponins,ardisiacrispins A (2) and B (3), were isolated from the whole plants of Ardisia pusilla A. DC. Their structures were elucidated by extensive spectral analysis and chemical evidences. Saponins 1 and 3 exhibited significant cytotoxicity against human glioblastoma U251MG cells.
A new triterpenoid saponin, 3-O-{β-D-xylopyranosyl-(1→2)-b-D-glucopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→2)]-a-L-arabinopyranosyl}-3β,16α,28α-trihydroxy-13β,28-epoxy-oleanan-30-al (ardipusilloside Ⅲ, 1), together with two known saponins,ardisiacrispins A (2) and B (3), were isolated from the whole plants of Ardisia pusilla A. DC. Their structures were elucidated by extensive spectral analysis and chemical evidences. Saponins 1 and 3 exhibited significant cytotoxicity against human glioblastoma U251MG cells.
2009, 20(2): 197-200
doi: 10.1016/j.cclet.2008.10.041
Abstract:
One new ceanothane-type triterpene and one new sesquiterpene, together with two known triterpenes were isolated from the fruits of Ziziphus jujuba Mill. (Rhamnaceae). Based on the spectral analyses, the structures of two new compounds were elucidated as 2a-aldehydo-A(1)-norlup-20(29)-en-27,28-dioic acid (zizyberanal acid) (1), and zizyberanone (2). While the two known triterpenes were identified as zizyberanalic acid (3) and ursolic acid (4).
One new ceanothane-type triterpene and one new sesquiterpene, together with two known triterpenes were isolated from the fruits of Ziziphus jujuba Mill. (Rhamnaceae). Based on the spectral analyses, the structures of two new compounds were elucidated as 2a-aldehydo-A(1)-norlup-20(29)-en-27,28-dioic acid (zizyberanal acid) (1), and zizyberanone (2). While the two known triterpenes were identified as zizyberanalic acid (3) and ursolic acid (4).
2009, 20(2): 201-203
doi: 10.1016/j.cclet.2008.10.040
Abstract:
Two new ent-kaurane diterpenoids taihangexcisoidesin A and B (1 and 2), were isolated from the EtOAc extract of the leaves of Isodon excisoides. Their structures were determined on the basis of spectroscopic methods.
Two new ent-kaurane diterpenoids taihangexcisoidesin A and B (1 and 2), were isolated from the EtOAc extract of the leaves of Isodon excisoides. Their structures were determined on the basis of spectroscopic methods.
2009, 20(2): 204-206
doi: 10.1016/j.cclet.2008.10.043
Abstract:
The catalytic and signaling activities of insulin receptor kinase (IRK) are regulated by the autophosphorylation of three tyrosine residues in a cytoplasmic protein-tyrosine kinase domain at Tyro 1158, Tyro 1162 and Tyro 1163. In this study, time-course of the auphosphorylation of the core kinase (residues 978-1283) from IRK was directly investigated by online electrospray ionization mass spectrometry. It is found that two tyrosine residues were phosphorylated in reaction time range of 30 min. This study implies that mass spectrometric technique must be a powerful tool to directly monitor the biological macromolecular modification and will also provide the information of the order and the mechanism of autophosphorylation at the tyrosine sites coupled with tandem mass spectrometric technique.
The catalytic and signaling activities of insulin receptor kinase (IRK) are regulated by the autophosphorylation of three tyrosine residues in a cytoplasmic protein-tyrosine kinase domain at Tyro 1158, Tyro 1162 and Tyro 1163. In this study, time-course of the auphosphorylation of the core kinase (residues 978-1283) from IRK was directly investigated by online electrospray ionization mass spectrometry. It is found that two tyrosine residues were phosphorylated in reaction time range of 30 min. This study implies that mass spectrometric technique must be a powerful tool to directly monitor the biological macromolecular modification and will also provide the information of the order and the mechanism of autophosphorylation at the tyrosine sites coupled with tandem mass spectrometric technique.
2009, 20(2): 207-209
doi: 10.1016/j.cclet.2008.10.036
Abstract:
In the present work, a novel analytical method was proposed for the determination of toluene diisocyanate (TDI) in syntheticrubber track by ion chromatography (IC) coupled with an ultraviolet detector setting at 212 nm. TDI can be hydrolyzed to toluene diamine (TDA) which can be separated by cation-exchange IC easily. The optimum IC separation was performed on an IonPac CS12A column (150 mm×4.0 mm) using 20 mmol L-1 sodium sulfate, 10 mmol L-1 sulfuric acid and 10% acetonitrile as eluent.It was found that a higher signal response of TDA could be obtained under alkaline condition. A suppressor was used to change the acidic eluent into alkaline one. 0.8 mol L-1 potassium hydroxide was chosen as the optimum regeneration eluent. With the added suppressor and regenerant, signal response was magnified by about 16 times and lower limit of detection (LOD, 0.13μg L-1) was obtained. Within-day relative standard deviation (R.S.D.) was less than 3.6%. The recoveries of TDI spiked in synthetic-rubber track samples were 96.4-110.6%.
In the present work, a novel analytical method was proposed for the determination of toluene diisocyanate (TDI) in syntheticrubber track by ion chromatography (IC) coupled with an ultraviolet detector setting at 212 nm. TDI can be hydrolyzed to toluene diamine (TDA) which can be separated by cation-exchange IC easily. The optimum IC separation was performed on an IonPac CS12A column (150 mm×4.0 mm) using 20 mmol L-1 sodium sulfate, 10 mmol L-1 sulfuric acid and 10% acetonitrile as eluent.It was found that a higher signal response of TDA could be obtained under alkaline condition. A suppressor was used to change the acidic eluent into alkaline one. 0.8 mol L-1 potassium hydroxide was chosen as the optimum regeneration eluent. With the added suppressor and regenerant, signal response was magnified by about 16 times and lower limit of detection (LOD, 0.13μg L-1) was obtained. Within-day relative standard deviation (R.S.D.) was less than 3.6%. The recoveries of TDI spiked in synthetic-rubber track samples were 96.4-110.6%.
2009, 20(2): 210-212
doi: 10.1016/j.cclet.2008.11.006
Abstract:
A novel mode-filtered light gas sensor has been reported. It was constructed by inserting an optical fiber deposited by a thin silicone cladding of cryptophane A into a fused-silica capillary. When different concentration of methane gas was introduced to the sensor, the phenomenon that mode-filtered light intensity decreased with the increasing concentration of methane was observed. And a linear relationship was obtained within the methane concentration range of 0.0-16.0% (v/v). The detection limit was 0.06% (v/v). The mode-filtered light sensor has been exploited to respond to various concentrations of methane gas at room temperature.
A novel mode-filtered light gas sensor has been reported. It was constructed by inserting an optical fiber deposited by a thin silicone cladding of cryptophane A into a fused-silica capillary. When different concentration of methane gas was introduced to the sensor, the phenomenon that mode-filtered light intensity decreased with the increasing concentration of methane was observed. And a linear relationship was obtained within the methane concentration range of 0.0-16.0% (v/v). The detection limit was 0.06% (v/v). The mode-filtered light sensor has been exploited to respond to various concentrations of methane gas at room temperature.
2009, 20(2): 213-216
doi: 10.1016/j.cclet.2008.10.047
Abstract:
A novel method for the determination of five carbamate pesticides (metolcarb, carbofuran, carbaryl, isoprocard and diethofencard) in water samples was developed by dispersive liquid-liquid microextraction (DLLME) coupled with high performance liquid chromatography-diode array detector (HPLC-DAD). Some experimental parameters that influence the extraction efficiency were studied and optimized to obtain the best extraction results. Under the optimum conditions for the method, the calibration curve was linear in the concentration range from 5 to 1000 ng mL-1 for all the five carbamate pesticides,with the correlation coefficients (r2) varying from 0.9984 to 0.9994. Good enrichment factors were achieved ranging from 80 to 177-fold, depending on the compound. The limits of detection (LODs) (S/N=3) were ranged from 0.1 to 0.5 ng mL-1. The method has been successfully applied to the analysis of the pesticide residues in environmental water samples.
A novel method for the determination of five carbamate pesticides (metolcarb, carbofuran, carbaryl, isoprocard and diethofencard) in water samples was developed by dispersive liquid-liquid microextraction (DLLME) coupled with high performance liquid chromatography-diode array detector (HPLC-DAD). Some experimental parameters that influence the extraction efficiency were studied and optimized to obtain the best extraction results. Under the optimum conditions for the method, the calibration curve was linear in the concentration range from 5 to 1000 ng mL-1 for all the five carbamate pesticides,with the correlation coefficients (r2) varying from 0.9984 to 0.9994. Good enrichment factors were achieved ranging from 80 to 177-fold, depending on the compound. The limits of detection (LODs) (S/N=3) were ranged from 0.1 to 0.5 ng mL-1. The method has been successfully applied to the analysis of the pesticide residues in environmental water samples.
2009, 20(2): 217-220
doi: 10.1016/j.cclet.2008.10.026
Abstract:
A carbon paste electrode modified with electropolymerized films of isonicotinic acid was developed. The modified electrode shows excellent electrocatalytic activity toward the oxidation of both dopamine (DA) and epinephrine (EP). Separation of the reduction peak potentials for dopamine and epinephrine was about 357 mV in pH 5.3 phosphate buffer solution (PBS) and the character was used for the detection DA and EP simultaneously. The peak currents increase linearly with DA and EP concentration over the range of 8.0×10-5 to 7.0×10-4 mol/L and 5.0×10-6 to 1.0×10-4 mol/L with detection limits of 2×10-5 and 1×10-6 mol/L, respectively. The interference studies showed that the modified electrode exhibits excellent selectivity in the presence of large excess of ascorbic acid (AA).
A carbon paste electrode modified with electropolymerized films of isonicotinic acid was developed. The modified electrode shows excellent electrocatalytic activity toward the oxidation of both dopamine (DA) and epinephrine (EP). Separation of the reduction peak potentials for dopamine and epinephrine was about 357 mV in pH 5.3 phosphate buffer solution (PBS) and the character was used for the detection DA and EP simultaneously. The peak currents increase linearly with DA and EP concentration over the range of 8.0×10-5 to 7.0×10-4 mol/L and 5.0×10-6 to 1.0×10-4 mol/L with detection limits of 2×10-5 and 1×10-6 mol/L, respectively. The interference studies showed that the modified electrode exhibits excellent selectivity in the presence of large excess of ascorbic acid (AA).
2009, 20(2): 221-224
doi: 10.1016/j.cclet.2008.10.039
Abstract:
Simultaneous determination of epinephrine (EP) and dopamine (DA) at 2,3-dimercaptosuccinic acid (DMSA) modified electrode was studied. The oxidation peaks of the mixture of EP and DA appeared at the same potential, but the cathodic peak currents were only linear to the concentration of DA, whereas the anodic peak currents were equal to the sum of individual anodic peak currents of EP and DA. Therefore, a novel electrochemical method for the simultaneous determination of EP and DA at a DMSA modified electrode (DMSA/Au electrode) by cyclic voltammetry was established. The DMSA self-assembled electrode showed good sensitivity, selectivity and stability and could be used to determine DA and EP, simultaneously, in the real application with satisfactory results.
Simultaneous determination of epinephrine (EP) and dopamine (DA) at 2,3-dimercaptosuccinic acid (DMSA) modified electrode was studied. The oxidation peaks of the mixture of EP and DA appeared at the same potential, but the cathodic peak currents were only linear to the concentration of DA, whereas the anodic peak currents were equal to the sum of individual anodic peak currents of EP and DA. Therefore, a novel electrochemical method for the simultaneous determination of EP and DA at a DMSA modified electrode (DMSA/Au electrode) by cyclic voltammetry was established. The DMSA self-assembled electrode showed good sensitivity, selectivity and stability and could be used to determine DA and EP, simultaneously, in the real application with satisfactory results.
2009, 20(2): 225-228
doi: 10.1016/j.cclet.2008.10.028
Abstract:
This study assessed the treatment of azo dye Acid Orange 7(AO7) containing wastewater by laboratory-scale up-flow constructed wetland (UFCW) with and without supplementary aeration. The supplementary aeration could effectively control the ratio of anaerobic and aerobic zones in the UFCW reactor. The results clearly show the supplementary aeration boosted the biodegradation of organic pollutants and mineralization of intermediate aromatic amines formed by AO7 degradation.
This study assessed the treatment of azo dye Acid Orange 7(AO7) containing wastewater by laboratory-scale up-flow constructed wetland (UFCW) with and without supplementary aeration. The supplementary aeration could effectively control the ratio of anaerobic and aerobic zones in the UFCW reactor. The results clearly show the supplementary aeration boosted the biodegradation of organic pollutants and mineralization of intermediate aromatic amines formed by AO7 degradation.
2009, 20(2): 229-230
doi: 10.1016/j.cclet.2008.10.031
Abstract:
A novel aromatic dianhydride monomer, 3,3'-oxybis[(3,4-dicarboxyphenoxy)phenol] dianhydride, was successfully synthesized in three steps using 3,3'-oxybis(phenol) as starting material, which was reacted with 4,4'-oxydianiline (ODA) via a conventional thermal or chemical imidization method to produce a new polyimide. The resulting polyimide exhibited excellent solubility, and film-forming capability.
A novel aromatic dianhydride monomer, 3,3'-oxybis[(3,4-dicarboxyphenoxy)phenol] dianhydride, was successfully synthesized in three steps using 3,3'-oxybis(phenol) as starting material, which was reacted with 4,4'-oxydianiline (ODA) via a conventional thermal or chemical imidization method to produce a new polyimide. The resulting polyimide exhibited excellent solubility, and film-forming capability.
2009, 20(2): 231-234
doi: 10.1016/j.cclet.2008.10.044
Abstract:
Reported here is fabrication of optically active micelles with broad range of morphologies in water, such as spheres, cylinders,and vesicles, from self-assembly of poly(ethylene glycol) monomethyl ether-b-poly-(methacryloyl-L-leucine methyl ester) (MPEG-b-PMALM) copolymer, which was prepared via atom transfer radical polymerization (ATRP) from vinyl monomer bearing chiral amino acid moieties, N-methacryloyl L-leucine methyl ester (MALM), using bromine (Br) end-capped poly(ethylene golycol) monomethylether (MPEG-Br) as macroinitiator in the presence of CuBr/Me6TREN as catalytic system.
Reported here is fabrication of optically active micelles with broad range of morphologies in water, such as spheres, cylinders,and vesicles, from self-assembly of poly(ethylene glycol) monomethyl ether-b-poly-(methacryloyl-L-leucine methyl ester) (MPEG-b-PMALM) copolymer, which was prepared via atom transfer radical polymerization (ATRP) from vinyl monomer bearing chiral amino acid moieties, N-methacryloyl L-leucine methyl ester (MALM), using bromine (Br) end-capped poly(ethylene golycol) monomethylether (MPEG-Br) as macroinitiator in the presence of CuBr/Me6TREN as catalytic system.
2009, 20(2): 235-237
doi: 10.1016/j.cclet.2008.10.002
Abstract:
A novel conjugated polymer containing azobenzene and oxadiazole units was synthesized through multi-step synthesis. The structures and properties of monomer and polymer were characterized and evaluated with IR, 1H NMR, UV, TGA and GPC,respectively. Polymer with long side chain of alkoxy shows good solubility, thermal stability and photoisomerization property.
A novel conjugated polymer containing azobenzene and oxadiazole units was synthesized through multi-step synthesis. The structures and properties of monomer and polymer were characterized and evaluated with IR, 1H NMR, UV, TGA and GPC,respectively. Polymer with long side chain of alkoxy shows good solubility, thermal stability and photoisomerization property.
2009, 20(2): 238-240
doi: 10.1016/j.cclet.2008.11.005
Abstract:
The liquid-phase direct catalytic amination of benzene to aniline was performed in acetic acid water solvent using a series of vanadium (Ⅲ, Ⅳ, Ⅴ) complexes with N,O-or O,O-ligands as catalysts and hydroxylamine hydrochloride as the aminating agent.The vanadium complexes exhibited much higher selectivity towards the production of aniline than NaVO3 or VOSO4. Under the optimized conditions, an aniline yield of 42.5% and a TON of 48 with a high selectivity of above 99.9% was obtained using 0.2 mmol of [VO(OAc)2] as the catalyst.
The liquid-phase direct catalytic amination of benzene to aniline was performed in acetic acid water solvent using a series of vanadium (Ⅲ, Ⅳ, Ⅴ) complexes with N,O-or O,O-ligands as catalysts and hydroxylamine hydrochloride as the aminating agent.The vanadium complexes exhibited much higher selectivity towards the production of aniline than NaVO3 or VOSO4. Under the optimized conditions, an aniline yield of 42.5% and a TON of 48 with a high selectivity of above 99.9% was obtained using 0.2 mmol of [VO(OAc)2] as the catalyst.
2009, 20(2): 241-244
doi: 10.1016/j.cclet.2008.10.053
Abstract:
We herein report a one-step, wet-chemical approach to synthesizing gold nanoplates in large quantities via the AuCl4- thermal reduction process by aniline, without introducing additional capping agent or surfactant. It is found that the reduction kinetics of AuCl4- is greatly altered by varying the initial molar ratio of aniline to AuCl4-. Moreover, further investigation reveals that the insitu formed polyaniline could serve effectively as a capping agent to preferably adsorb the {111} facets of gold crystals during a slow reduction process, directing the formation of gold nanoplates.
We herein report a one-step, wet-chemical approach to synthesizing gold nanoplates in large quantities via the AuCl4- thermal reduction process by aniline, without introducing additional capping agent or surfactant. It is found that the reduction kinetics of AuCl4- is greatly altered by varying the initial molar ratio of aniline to AuCl4-. Moreover, further investigation reveals that the insitu formed polyaniline could serve effectively as a capping agent to preferably adsorb the {111} facets of gold crystals during a slow reduction process, directing the formation of gold nanoplates.
2009, 20(2): 245-249
doi: 10.1016/j.cclet.2008.10.010
Abstract:
Calorimetric measurements in 0.8[xB2O3-(1-x)SiO2]-0.2Na2O glasses and melts are performed in HF calorimetry at 298 K and lead borate calorimetry at 973 K, respectively. Mixing enthalpy is affected by both temperature and composition. At 298 K, the mixing enthalpies are slightly negative and components are miscible at that temperature in the whole composition range. At 973 K,the sign of the mixing enthalpies reflect the tendency to phase separation at silica-rich compositions, which is avoided for kinetic reasons as shown by SEM results. Therefore, one is tempted to consider the quenched 0.8[xB2O3-(1-x)SiO2-0.20Na2O] glasses and melts as single-phase materials.
Calorimetric measurements in 0.8[xB2O3-(1-x)SiO2]-0.2Na2O glasses and melts are performed in HF calorimetry at 298 K and lead borate calorimetry at 973 K, respectively. Mixing enthalpy is affected by both temperature and composition. At 298 K, the mixing enthalpies are slightly negative and components are miscible at that temperature in the whole composition range. At 973 K,the sign of the mixing enthalpies reflect the tendency to phase separation at silica-rich compositions, which is avoided for kinetic reasons as shown by SEM results. Therefore, one is tempted to consider the quenched 0.8[xB2O3-(1-x)SiO2-0.20Na2O] glasses and melts as single-phase materials.
2009, 20(2): 250-252
doi: 10.1016/j.cclet.2008.10.011
Abstract:
A novel cobalt-free perovskite based on Ba0.5Sr0.5Fe0.8Zn0.2O3-δ (BSFZ) were prepared by EDTA-citric acid method. The lattice constants of the BSFZ perovskite were characterized by in situ high-temperature X-ray diffraction (HTXRD). The thermal expansion coefficient of BSFZ is 10.5×10-6 K-1, which is lower than that of cobalt-based perovskite materials. The BSFZ membrane was also used to construct reactors for the partial oxidation of methane (POM) to syngas. Results show that the BSFZ membrane can be operated for the POM reaction for more than 100 h without any fractures. The CO selectivity of 97% is obtained.The steady oxygen permeation flux reaches around 2.5 mL/min cm2 during POM reaction.
A novel cobalt-free perovskite based on Ba0.5Sr0.5Fe0.8Zn0.2O3-δ (BSFZ) were prepared by EDTA-citric acid method. The lattice constants of the BSFZ perovskite were characterized by in situ high-temperature X-ray diffraction (HTXRD). The thermal expansion coefficient of BSFZ is 10.5×10-6 K-1, which is lower than that of cobalt-based perovskite materials. The BSFZ membrane was also used to construct reactors for the partial oxidation of methane (POM) to syngas. Results show that the BSFZ membrane can be operated for the POM reaction for more than 100 h without any fractures. The CO selectivity of 97% is obtained.The steady oxygen permeation flux reaches around 2.5 mL/min cm2 during POM reaction.
