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2008 Volume 19 Issue 12
2008, 19(12): 1391-1394
doi: 10.1016/j.cclet.2008.09.055
Abstract:
The symmetrical diketone Ⅱ, which can be synthesized in gram scale using a well established method, was used as a starting material to prepare the 11a-methoxy ketomethylene Ⅵ. This is in continuation of our study aiming at the synthesis of multi-hydroxylated cephalostatin analogues, as for example cephalostatin 1 Ⅰ, a potent anti-tumor natural product. Compound Ⅵ underwent chemo- and regioselective hydroboration reaction at only one of △14,15 double bonds furnishing compound Ⅸ as a major product in a fair yield.
The symmetrical diketone Ⅱ, which can be synthesized in gram scale using a well established method, was used as a starting material to prepare the 11a-methoxy ketomethylene Ⅵ. This is in continuation of our study aiming at the synthesis of multi-hydroxylated cephalostatin analogues, as for example cephalostatin 1 Ⅰ, a potent anti-tumor natural product. Compound Ⅵ underwent chemo- and regioselective hydroboration reaction at only one of △14,15 double bonds furnishing compound Ⅸ as a major product in a fair yield.
2008, 19(12): 1395-1397
doi: 10.1016/j.cclet.2008.09.034
Abstract:
A series of quinolone derivatives containing benzimidazole, benzoxazole or benzothiazole ring were synthesized. The cytotoxicity of 12 new compounds was evaluated in KB, Be17402, A2780 and HT-29 cell lines. Most of synthesized compounds showed moderate inhibitory activity against cancer cells. The inhibitory activities of 6k, against KB and A2780 tumor cells are comparable to that of topotecan, one of topoisomerase I inhibitors.
A series of quinolone derivatives containing benzimidazole, benzoxazole or benzothiazole ring were synthesized. The cytotoxicity of 12 new compounds was evaluated in KB, Be17402, A2780 and HT-29 cell lines. Most of synthesized compounds showed moderate inhibitory activity against cancer cells. The inhibitory activities of 6k, against KB and A2780 tumor cells are comparable to that of topotecan, one of topoisomerase I inhibitors.
2008, 19(12): 1398-1400
doi: 10.1016/j.cclet.2008.09.046
Abstract:
Three new functional group containing borazine derivatives, 2,4,6-tri(allylamino)borazine, 2,4,6-tri(3-ethynylanilino)borazine, and 2,4,6-tri(4-propargyl oxyanilino)borazine were synthesized by aminolysis reaction of 2,4,6-trichloroborazine Cl3B3N3H3 (TCB). The new compounds were characterized by infrared (IR) spectra, nuclear magnetic resonance (NMR), and mass spectrometry (MS).
Three new functional group containing borazine derivatives, 2,4,6-tri(allylamino)borazine, 2,4,6-tri(3-ethynylanilino)borazine, and 2,4,6-tri(4-propargyl oxyanilino)borazine were synthesized by aminolysis reaction of 2,4,6-trichloroborazine Cl3B3N3H3 (TCB). The new compounds were characterized by infrared (IR) spectra, nuclear magnetic resonance (NMR), and mass spectrometry (MS).
2008, 19(12): 1401-1402
doi: 10.1016/j.cclet.2008.09.053
Abstract:
The mixture of cesium hydroxide and terminal alkynes in dry DMF in the presence of 4(Å), molecular sieves was stirred for 3.0 h at room temperature under N2, then aryltellurenyl bromide in THF was added, and the reaction mixture was stirred for 2.0 h. Alkynyl tellurides were obtained in about 90% yields by flash chromatography.
The mixture of cesium hydroxide and terminal alkynes in dry DMF in the presence of 4(Å), molecular sieves was stirred for 3.0 h at room temperature under N2, then aryltellurenyl bromide in THF was added, and the reaction mixture was stirred for 2.0 h. Alkynyl tellurides were obtained in about 90% yields by flash chromatography.
2008, 19(12): 1403-1406
doi: 10.1016/j.cclet.2008.07.016
Abstract:
Oxidative cyclocondensation of o-aminobenzamide with various aldehydes in water using I2/KI as catalyst and oxidizing agent is carded out giving the corresponding quinazolin-4(3H)-ones 3a-n in good to excellent yields.
Oxidative cyclocondensation of o-aminobenzamide with various aldehydes in water using I2/KI as catalyst and oxidizing agent is carded out giving the corresponding quinazolin-4(3H)-ones 3a-n in good to excellent yields.
2008, 19(12): 1407-1410
doi: 10.1016/j.cclet.2008.07.001
Abstract:
The synthesis of a new series of six-membered N,N'-diarylsubstituted methylene-bis-dihydro-2H-1,3-benzoxazines (5a-e) was achieved in excellent yields by Mannich-type condensation of N,N'-diarylsubstituted methylene-bis-o-hydroxybenzyl amines (4a-e) with formaldehyde in chloroform at reflux. These amines (4a-e) were obtained by the reduction of N,N'-diarylsubstituted methylene-bis-o-hydroxybenzyl imines (3a-e) with NaBH4, which inturn were obtained by the condensation of methylene-bis-salicylaldehyde (2) with various substituted arylamines.
The synthesis of a new series of six-membered N,N'-diarylsubstituted methylene-bis-dihydro-2H-1,3-benzoxazines (5a-e) was achieved in excellent yields by Mannich-type condensation of N,N'-diarylsubstituted methylene-bis-o-hydroxybenzyl amines (4a-e) with formaldehyde in chloroform at reflux. These amines (4a-e) were obtained by the reduction of N,N'-diarylsubstituted methylene-bis-o-hydroxybenzyl imines (3a-e) with NaBH4, which inturn were obtained by the condensation of methylene-bis-salicylaldehyde (2) with various substituted arylamines.
2008, 19(12): 1411-1414
doi: 10.1016/j.cclet.2008.09.030
Abstract:
A novel application of horseradish peroxidase (HRP) in the oxidation of alcohol ethoxylate to alkylether carboxylie acid in the present of H2O2 was reported in this paper. We propose the mechanism for the catalytic oxidation reaction is that the hydrogen transfers from the substrate to the ferryl oxygen to form the α-hydroxy carbon radical intermediate. The reaction offers a new approach for further research structure and catalytic mechanism of HRP and production of alkylether carboxylic acid.
A novel application of horseradish peroxidase (HRP) in the oxidation of alcohol ethoxylate to alkylether carboxylie acid in the present of H2O2 was reported in this paper. We propose the mechanism for the catalytic oxidation reaction is that the hydrogen transfers from the substrate to the ferryl oxygen to form the α-hydroxy carbon radical intermediate. The reaction offers a new approach for further research structure and catalytic mechanism of HRP and production of alkylether carboxylic acid.
2008, 19(12): 1415-1418
doi: 10.1016/j.cclet.2008.09.025
Abstract:
Synthesis of novel 3-ary1-5-(3,5-dimethylisoxazol-4-y1)-2,3,5,6-tetrahydrobenzo[g][1,3,5]oxadiazocine-4-thiones 5 has been accomplished from 3,5-dimethylisoxazol-4-amine 1 by condensation with salicylaldehydes, followed by reduction, treatment with aryl isothiocyanates and subsequent smooth ring closure via acetal formation in the presence of formaldehyde.
Synthesis of novel 3-ary1-5-(3,5-dimethylisoxazol-4-y1)-2,3,5,6-tetrahydrobenzo[g][1,3,5]oxadiazocine-4-thiones 5 has been accomplished from 3,5-dimethylisoxazol-4-amine 1 by condensation with salicylaldehydes, followed by reduction, treatment with aryl isothiocyanates and subsequent smooth ring closure via acetal formation in the presence of formaldehyde.
2008, 19(12): 1419-1422
doi: 10.1016/j.cclet.2008.09.018
Abstract:
Eighteen 2',4'-difluoro-3-(carbamoyl)biphenyl-4-yl benzoates were synthesized from diflunisal in three steps with total yields from 72% to 86%. All compounds were identified by IR, 1H NMR, MS and elemental analysis. The anti-inflammatory activity and analgesic activity for 18 compounds were evaluated. The preliminary assay results showed that compounds 4a and 4p exhibited potent anti-inflammatory-analgesic activity.
Eighteen 2',4'-difluoro-3-(carbamoyl)biphenyl-4-yl benzoates were synthesized from diflunisal in three steps with total yields from 72% to 86%. All compounds were identified by IR, 1H NMR, MS and elemental analysis. The anti-inflammatory activity and analgesic activity for 18 compounds were evaluated. The preliminary assay results showed that compounds 4a and 4p exhibited potent anti-inflammatory-analgesic activity.
2008, 19(12): 1423-1426
doi: 10.1016/j.cclet.2008.09.048
Abstract:
Fe(HSO4)3 has been used as an efficient and reeyclable catalyst for the one-pot synthesis of 14-aryl- or alkyl-14H-dibenzo[a,j]xanthene derivatives by the reaction of 2-naphtol and aldehydes. Different types of aromatic and aliphatic aldehydes are used in the reaction and in all cases the products were obtained in good to excellent yields.
Fe(HSO4)3 has been used as an efficient and reeyclable catalyst for the one-pot synthesis of 14-aryl- or alkyl-14H-dibenzo[a,j]xanthene derivatives by the reaction of 2-naphtol and aldehydes. Different types of aromatic and aliphatic aldehydes are used in the reaction and in all cases the products were obtained in good to excellent yields.
2008, 19(12): 1427-1430
doi: 10.1016/j.cclet.2008.09.029
Abstract:
A series of new 1-(alkenoyl/hydroxyalkenoyl)-4-benzoyl-thiosemicarbazides 2a-d and 2-benzamide-5-alkenyl/hydroxyalk-enyl-1,3,4-thiadiazoles 3a-d were synthesized from fatty acid hydrazides. Structure of all these compounds was confirmed by IR, 1H NMR, 13C NMR, mass spectra and elemental analysis. The bioassay results indicate that some compounds 2c, 2d, 3c and 3d have good antibacterial activity.
A series of new 1-(alkenoyl/hydroxyalkenoyl)-4-benzoyl-thiosemicarbazides 2a-d and 2-benzamide-5-alkenyl/hydroxyalk-enyl-1,3,4-thiadiazoles 3a-d were synthesized from fatty acid hydrazides. Structure of all these compounds was confirmed by IR, 1H NMR, 13C NMR, mass spectra and elemental analysis. The bioassay results indicate that some compounds 2c, 2d, 3c and 3d have good antibacterial activity.
2008, 19(12): 1431-1434
doi: 10.1016/j.cclet.2008.09.027
Abstract:
Direct chemoselective oxidation of 8-lactones via highly stable benzyl radical cyclization is reported. The one-pot conversion of premade substituted 5-aryl pentanoic acid and 8-benzyl-1-naphthoic acid in the presence of K2S2O8-CuCl2 results to the δ-lactones in moderate to good yields. The advantages of this methodology is using water as a solvent and utilizing available starting materials.
Direct chemoselective oxidation of 8-lactones via highly stable benzyl radical cyclization is reported. The one-pot conversion of premade substituted 5-aryl pentanoic acid and 8-benzyl-1-naphthoic acid in the presence of K2S2O8-CuCl2 results to the δ-lactones in moderate to good yields. The advantages of this methodology is using water as a solvent and utilizing available starting materials.
2008, 19(12): 1435-1439
doi: 10.1016/j.cclet.2008.09.028
Abstract:
An efficient three-component synthesis of 3A-dihydropyrimidinones using MCM-41 anchored sulfonic acid (MCM-41-R-SO3H) as a mild, heterogeneous catalyst for Biginelli reaction in CH3CN under reflux condition is described.
An efficient three-component synthesis of 3A-dihydropyrimidinones using MCM-41 anchored sulfonic acid (MCM-41-R-SO3H) as a mild, heterogeneous catalyst for Biginelli reaction in CH3CN under reflux condition is described.
2008, 19(12): 1440-1444
doi: 10.1016/j.cclet.2008.09.049
Abstract:
An efficient synthesis of cinchona alkaloid-derived ligands based on solvent-free microwave-assisted reaction was described. The coupling of 1,4-dichlorophthalazine or 3,6-dichloropyridazine with quinine, cinchonine or cinchonidine provide bis- or mono-cinchona alkaloid-derived ligands in moderate to good yields (52-89%) within 15 rain under optimum microwave conditions.
An efficient synthesis of cinchona alkaloid-derived ligands based on solvent-free microwave-assisted reaction was described. The coupling of 1,4-dichlorophthalazine or 3,6-dichloropyridazine with quinine, cinchonine or cinchonidine provide bis- or mono-cinchona alkaloid-derived ligands in moderate to good yields (52-89%) within 15 rain under optimum microwave conditions.
2008, 19(12): 1445-1446
doi: 10.1016/j.cclet.2008.09.037
Abstract:
A new cytotoxic bufadienolide was isolated from the traditional Chinese medicine-Chansu. The structure of new compound was elucidated on the basis of spectral methods including 2D NMR. And it showed strong in vitro eytotoxic activity against Hela cells with IC50 of 8.06×10-2 μmol/L.
A new cytotoxic bufadienolide was isolated from the traditional Chinese medicine-Chansu. The structure of new compound was elucidated on the basis of spectral methods including 2D NMR. And it showed strong in vitro eytotoxic activity against Hela cells with IC50 of 8.06×10-2 μmol/L.
2008, 19(12): 1447-1449
doi: 10.1016/j.cclet.2008.09.035
Abstract:
The continuous chemical investigation on the ethyl acetate (EtOAc) soluble fraction of the MeOH extract afforded two new lanostane triterpenoid derivatives including one with a rearranged lanostane skeleton. They were identified as 3,4-seco-8-(14→13R)abeo-17,13-friedo-9β-lanosta-4(28), 7,14(30),24-tetraen-26,23-olide-23-hydroxy-3-oic acid (1) and 7,14-mariesadien-3α-hydroxy-25-methoxy-26-oic acid (2). Structural determination of these compounds were carried out by the spectral studies especially by the two digital (2D)-NMR and high-resolution MS experiences.
The continuous chemical investigation on the ethyl acetate (EtOAc) soluble fraction of the MeOH extract afforded two new lanostane triterpenoid derivatives including one with a rearranged lanostane skeleton. They were identified as 3,4-seco-8-(14→13R)abeo-17,13-friedo-9β-lanosta-4(28), 7,14(30),24-tetraen-26,23-olide-23-hydroxy-3-oic acid (1) and 7,14-mariesadien-3α-hydroxy-25-methoxy-26-oic acid (2). Structural determination of these compounds were carried out by the spectral studies especially by the two digital (2D)-NMR and high-resolution MS experiences.
2008, 19(12): 1450-1452
doi: 10.1016/j.cclet.2008.09.054
Abstract:
A new cirmamic acid monoterpenoid ester, intermedin C (1), was isolated from the aerial parts of Schisandra propinqua var. intermedia. The structure of 1 was elucidated by spectroscopic methods including extensive 1D and 2D NMR techniques.
A new cirmamic acid monoterpenoid ester, intermedin C (1), was isolated from the aerial parts of Schisandra propinqua var. intermedia. The structure of 1 was elucidated by spectroscopic methods including extensive 1D and 2D NMR techniques.
2008, 19(12): 1453-1455
doi: 10.1016/j.cclet.2008.09.044
Abstract:
A new lavandulyl flavonoid was isolated from the rhizome of Sorphora flavescens. The structure of new compound was elucidated on the basis of spectral methods including 2D NMR. And it showed potent cytotoxic activity against Hela cells with IC50 of 1.1μmol/L.
A new lavandulyl flavonoid was isolated from the rhizome of Sorphora flavescens. The structure of new compound was elucidated on the basis of spectral methods including 2D NMR. And it showed potent cytotoxic activity against Hela cells with IC50 of 1.1μmol/L.
2008, 19(12): 1456-1458
doi: 10.1016/j.cclet.2008.09.042
Abstract:
From the ethanol extract of Selaginella moellendorffii Hieron., a new flavone O-glycoside and three known flavone C-glycosides have been isolated and identified as 5-carboxymethyl-4'-hydroxyflavone-7-O-β-D-glucopyranoside 1, 6,8-di-C-β-D-glucopyrano-sylapigenin 2, 6-C-β-D-glucopyranosyl-8-C-β-D-xylopyranosyl apigenin 3, 6-C-β-D-xylopyranosyl-8-C-β-D-glucopyranosylapi-genin 4, respectively. Their structures were elucidated by spectroscopic methods.
From the ethanol extract of Selaginella moellendorffii Hieron., a new flavone O-glycoside and three known flavone C-glycosides have been isolated and identified as 5-carboxymethyl-4'-hydroxyflavone-7-O-β-D-glucopyranoside 1, 6,8-di-C-β-D-glucopyrano-sylapigenin 2, 6-C-β-D-glucopyranosyl-8-C-β-D-xylopyranosyl apigenin 3, 6-C-β-D-xylopyranosyl-8-C-β-D-glucopyranosylapi-genin 4, respectively. Their structures were elucidated by spectroscopic methods.
2008, 19(12): 1459-1461
doi: 10.1016/j.cclet.2008.09.041
Abstract:
From the roots ethanol extract of Glehnia littoralis, two new lignan glycosides, named glehlinoside E (1) and F (2), were obtained. Their structures were determined to be (-)-secoisolariciresinol 4-O-β-D-(6-O-feruloyl) glucopyranoside (1) and (-)-secoisolariciresinol 4-O-β-D-(6-O-caffeloyl) glucopyranoside (2) by analysis of their spectral data, respectively.
From the roots ethanol extract of Glehnia littoralis, two new lignan glycosides, named glehlinoside E (1) and F (2), were obtained. Their structures were determined to be (-)-secoisolariciresinol 4-O-β-D-(6-O-feruloyl) glucopyranoside (1) and (-)-secoisolariciresinol 4-O-β-D-(6-O-caffeloyl) glucopyranoside (2) by analysis of their spectral data, respectively.
2008, 19(12): 1462-1464
doi: 10.1016/j.cclet.2008.09.051
Abstract:
A new triterpene glycoside, leueospilotaside C, along with two known saponin, was isolated from sea cucumber Holothuria leucospilota collected from the South China Sea, and its structure was elucidated as 3-O-{4'-O-sodiumsulfate-β-D-xylopyranosyl}-holosta-22,25-epoxy-9-ene-3β, 12α, 17α-triol (1) by extensive spectroscopic analysis and chemical methods. The glycosides have the same triterpene aglycone, but differ in the oligosaccharide moieties.
A new triterpene glycoside, leueospilotaside C, along with two known saponin, was isolated from sea cucumber Holothuria leucospilota collected from the South China Sea, and its structure was elucidated as 3-O-{4'-O-sodiumsulfate-β-D-xylopyranosyl}-holosta-22,25-epoxy-9-ene-3β, 12α, 17α-triol (1) by extensive spectroscopic analysis and chemical methods. The glycosides have the same triterpene aglycone, but differ in the oligosaccharide moieties.
2008, 19(12): 1465-1469
doi: 10.1016/j.cclet.2008.09.039
Abstract:
The interaction between sanguinarine and guanosine was investigated by using UV-vis and fluorescence spectra at pH 7.2. The binding of sanguinarine to guanosine was substantiated by the hypochromism and bathochromism in the absorption spectra and the emission quenching in fluorescence spectra. The fluorescence lifetime results, the varieties of the fluorophore absorption spectra and the decrease of the binding constant with the increasing temperature all indicate that the fluorescence quenching is static. The ratio and constant of the binding cytidine to sanguinarine are 2 and 6.44×107, respectively. The result shows that the binding of sanguinarine to guanosine is not only exothermic but also entropy-driven with △H=-8.53 kJ/mol, △S=0.12 kJ/(mol K), and △G=-44.57 kJ/mol at 298.15 K.
The interaction between sanguinarine and guanosine was investigated by using UV-vis and fluorescence spectra at pH 7.2. The binding of sanguinarine to guanosine was substantiated by the hypochromism and bathochromism in the absorption spectra and the emission quenching in fluorescence spectra. The fluorescence lifetime results, the varieties of the fluorophore absorption spectra and the decrease of the binding constant with the increasing temperature all indicate that the fluorescence quenching is static. The ratio and constant of the binding cytidine to sanguinarine are 2 and 6.44×107, respectively. The result shows that the binding of sanguinarine to guanosine is not only exothermic but also entropy-driven with △H=-8.53 kJ/mol, △S=0.12 kJ/(mol K), and △G=-44.57 kJ/mol at 298.15 K.
2008, 19(12): 1470-1474
doi: 10.1016/j.cclet.2008.09.014
Abstract:
A novel method is developed for the determination of cefradine by using sodium nitroprusside as chromogenic reagent. The experiment indicates that a russety product is formed by the reaction of cefradine with sodium nin'oprusside in basic solution, and the maximum absorption wavelength (λmax) of russety product is 505 nm. And the sensitization of tetradecyl benzyl dimethyl ammonium chloride for the reaction of cefradine with sodium nitroprusside is remarkable. The apparent molar absorption coefficient (ε505)is 2.81×103 L/mol cm. The linear equation is A=0.0657+0.00804C (μg/mL) in the range of 1.50-55.0μg/mL of cefradine with a correlation coefficient r=0.9992, and the detection limit is 1.38μg/mL. This method has been applied to determine cefradine in capsule and tablet samples.
A novel method is developed for the determination of cefradine by using sodium nitroprusside as chromogenic reagent. The experiment indicates that a russety product is formed by the reaction of cefradine with sodium nin'oprusside in basic solution, and the maximum absorption wavelength (λmax) of russety product is 505 nm. And the sensitization of tetradecyl benzyl dimethyl ammonium chloride for the reaction of cefradine with sodium nitroprusside is remarkable. The apparent molar absorption coefficient (ε505)is 2.81×103 L/mol cm. The linear equation is A=0.0657+0.00804C (μg/mL) in the range of 1.50-55.0μg/mL of cefradine with a correlation coefficient r=0.9992, and the detection limit is 1.38μg/mL. This method has been applied to determine cefradine in capsule and tablet samples.
2008, 19(12): 1475-1478
doi: 10.1016/j.cclet.2008.09.033
Abstract:
A novel degradable pH-sensitive hydrogel with pendent carboxyl groups was designed and synthesized from ethylenediami-netetraacetic dianhydride (EDTAh) and butanediamine (BDA) with dicyclohexylcarbodiimide (DCC) as a condensating agent and BDA as a crosslinking agent. The obtained polymers were characterized by 13C NMR, 1H NMR and FTIR. The swelling experiments of the hydrogel in pH 3, 7, and 12 media indicated much higher swelling ratio in pH 12 media than in pH 3 and pH 7 media, exhibiting sound pH sensitivity. The pH sensitivity of this type of hydrogel may be regulated through controlling the type and the dose of the crosslinking agent.
A novel degradable pH-sensitive hydrogel with pendent carboxyl groups was designed and synthesized from ethylenediami-netetraacetic dianhydride (EDTAh) and butanediamine (BDA) with dicyclohexylcarbodiimide (DCC) as a condensating agent and BDA as a crosslinking agent. The obtained polymers were characterized by 13C NMR, 1H NMR and FTIR. The swelling experiments of the hydrogel in pH 3, 7, and 12 media indicated much higher swelling ratio in pH 12 media than in pH 3 and pH 7 media, exhibiting sound pH sensitivity. The pH sensitivity of this type of hydrogel may be regulated through controlling the type and the dose of the crosslinking agent.
2008, 19(12): 1479-1482
doi: 10.1016/j.cclet.2008.09.023
Abstract:
A series of analogs of endomorphin-2(EM-2) with phenylglycine (Phg) in position 3 or 4 were synthesized. In electrospray ionization Fourier transform ion cyclotron resonance (ESI-FT-ICR) MS/MS spectra of these compounds, some b, y, a, and internal ions were observed and slight mass differences between the calculated and observed results are obtained. Their sequences were derived successfully. However, the MS/MS patterns of these analogs with DPhg and Lphg were very similar. It is hard to distinguish them by MS/MS spectra. Moreover, if the third position was substituted by phenylglyeine (L or D), a rearrangement could occur in MS/MS experiment to lose proline residue.
A series of analogs of endomorphin-2(EM-2) with phenylglycine (Phg) in position 3 or 4 were synthesized. In electrospray ionization Fourier transform ion cyclotron resonance (ESI-FT-ICR) MS/MS spectra of these compounds, some b, y, a, and internal ions were observed and slight mass differences between the calculated and observed results are obtained. Their sequences were derived successfully. However, the MS/MS patterns of these analogs with DPhg and Lphg were very similar. It is hard to distinguish them by MS/MS spectra. Moreover, if the third position was substituted by phenylglyeine (L or D), a rearrangement could occur in MS/MS experiment to lose proline residue.
2008, 19(12): 1483-1486
doi: 10.1016/j.cclet.2008.09.040
Abstract:
Chloroperoxidase (CPO) was immobilized by konjac glucornannan (KGM) on the 1-butyl-3-methyl imidazolium tetrafluor-oborate [BMIM][BF4]/Nafion modified glassy carbon electrode. The electrochemical behaviors of the immobilized CPO were investigated by cyclic voltammetry. The results showed that CPO was successfully immobilized on the GCE and underwent fast direct electron transfer reactions with the formal potential at -0.3 V vs. SCE. The modified electrode showed a good catalytic activity for electrocatalytical reduction of O2 and H2O2.
Chloroperoxidase (CPO) was immobilized by konjac glucornannan (KGM) on the 1-butyl-3-methyl imidazolium tetrafluor-oborate [BMIM][BF4]/Nafion modified glassy carbon electrode. The electrochemical behaviors of the immobilized CPO were investigated by cyclic voltammetry. The results showed that CPO was successfully immobilized on the GCE and underwent fast direct electron transfer reactions with the formal potential at -0.3 V vs. SCE. The modified electrode showed a good catalytic activity for electrocatalytical reduction of O2 and H2O2.
2008, 19(12): 1487-1490
doi: 10.1016/j.cclet.2008.09.017
Abstract:
A new method for the determination of atrazine, simazine and prometryn in water samples by on-line sweeping concentration technique in micellar electrokinetic chromatography (MEKC) was developed. Various parameters affecting sample enrichment and separation efficiency were systematically studied. Compared with the conventional MEKC method, up to 60-200-fold improve-merit in concentration sensitivity was achieved in terms of peak height by using this sweeping injection technique. The compound strychnine was used as the internal standard for the improvement of the experimental reproducibility. The limits of detection (S/ N=3:1) for atrazine, simazine and prometryn were 9, 10 and 0.5 ng mL-1, respectively. This method has been successfully applied to the analysis of atrazine, simazine and prometryn in lake, steam and ground water.
A new method for the determination of atrazine, simazine and prometryn in water samples by on-line sweeping concentration technique in micellar electrokinetic chromatography (MEKC) was developed. Various parameters affecting sample enrichment and separation efficiency were systematically studied. Compared with the conventional MEKC method, up to 60-200-fold improve-merit in concentration sensitivity was achieved in terms of peak height by using this sweeping injection technique. The compound strychnine was used as the internal standard for the improvement of the experimental reproducibility. The limits of detection (S/ N=3:1) for atrazine, simazine and prometryn were 9, 10 and 0.5 ng mL-1, respectively. This method has been successfully applied to the analysis of atrazine, simazine and prometryn in lake, steam and ground water.
2008, 19(12): 1491-1494
doi: 10.1016/j.cclet.2008.09.052
Abstract:
A method for determination of lactose in food samples by Osteryoung square wave voltammetry (OSWV) was developed. It was based on the nucleophilic addition reaction between lactose and aqua ammonia. The carbonyl group of lactose can be changed into imido group, and this increases the electrochemical activity in reduction and the sensitivity. The optimal condition for the nucleophilic addition reaction was investigated and it was found that in NH4Cl-NH3 buffer of pH 10.1, the linear range between the peak current and the concentration of lactose was 0.6-8.4 mg L-1, and the detection limits was 0.44 mg L-1. The proposed method was applied to the "determination of lactose in food samples and satisfactory results were obtained.
A method for determination of lactose in food samples by Osteryoung square wave voltammetry (OSWV) was developed. It was based on the nucleophilic addition reaction between lactose and aqua ammonia. The carbonyl group of lactose can be changed into imido group, and this increases the electrochemical activity in reduction and the sensitivity. The optimal condition for the nucleophilic addition reaction was investigated and it was found that in NH4Cl-NH3 buffer of pH 10.1, the linear range between the peak current and the concentration of lactose was 0.6-8.4 mg L-1, and the detection limits was 0.44 mg L-1. The proposed method was applied to the "determination of lactose in food samples and satisfactory results were obtained.
2008, 19(12): 1495-1498
doi: 10.1016/j.cclet.2008.09.050
Abstract:
The micron-sized mierospheres with superparamagnetic property were synthesized with vinyl acetate and divinylbenzene by microsuspension polymerization. After the complete alcoholysis, these hydroxyl-functionalized microspheres were activated by divinylfone and modified with mercaptoethanol to prepare the thiophilic magnetic adsorbent, which was used to specifically isolate immunoglobulin G (IgG) from human serum. This thiophilic magnetic adsorbent performed an evident salt-dependent adsorption behavior for IgG. Due to their salt-promoted adsorption towards IgG under high salt concentration, the absorbed antibodies could be extracted in low salt concentration with high purity.
The micron-sized mierospheres with superparamagnetic property were synthesized with vinyl acetate and divinylbenzene by microsuspension polymerization. After the complete alcoholysis, these hydroxyl-functionalized microspheres were activated by divinylfone and modified with mercaptoethanol to prepare the thiophilic magnetic adsorbent, which was used to specifically isolate immunoglobulin G (IgG) from human serum. This thiophilic magnetic adsorbent performed an evident salt-dependent adsorption behavior for IgG. Due to their salt-promoted adsorption towards IgG under high salt concentration, the absorbed antibodies could be extracted in low salt concentration with high purity.
2008, 19(12): 1499-1503
doi: 10.1016/j.cclet.2008.09.056
Abstract:
Reaction of Zn(NO3)2·6H2O with 3-(4-carboxylphenylamino)-1-ferrocenyl-2-butylen-1-one (HL) and 4,4'-bipyridine (4,4'-bipy) in methanol solution resulted in a novel ladder-like coordination polymer {[Zn2L2(μ2-L)2(4,4'-bipy)2]·MeOH}n (1). Its crystal structure, thermal and electrochemical properties axe presented.
Reaction of Zn(NO3)2·6H2O with 3-(4-carboxylphenylamino)-1-ferrocenyl-2-butylen-1-one (HL) and 4,4'-bipyridine (4,4'-bipy) in methanol solution resulted in a novel ladder-like coordination polymer {[Zn2L2(μ2-L)2(4,4'-bipy)2]·MeOH}n (1). Its crystal structure, thermal and electrochemical properties axe presented.
2008, 19(12): 1504-1508
doi: 10.1016/j.cclet.2008.09.038
Abstract:
Isothermal oxidation behavior of chromium with and without nanometric sol-gel CeO2 coating is studied at 1000℃ in air. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to examine the surface morphology and microstructure of their oxide films. It is found that ceria coating greatly improves the anti-oxidation property of chromium. Laser Raman spectrometer and X-ray diffraction spectrometer (XRD) are also used to study the stress level in oxide films formed on ceria-coated and ceria-free Cr. The difference in oxidation behavior is mainly attributed to the fact that ceria greatly reduces the growth speed and grain size of Cr2O3 film, and this fine grain-sized Cr2O3 film probably has better high temperature plasticity, i.e. oxide film can relieve parts of compressive stress by means of creeping. XRD and Raman testing results both show the stress declination due to nano-CeO2 application, and their deviation is analyzed concerning to the rare earth effect.
Isothermal oxidation behavior of chromium with and without nanometric sol-gel CeO2 coating is studied at 1000℃ in air. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to examine the surface morphology and microstructure of their oxide films. It is found that ceria coating greatly improves the anti-oxidation property of chromium. Laser Raman spectrometer and X-ray diffraction spectrometer (XRD) are also used to study the stress level in oxide films formed on ceria-coated and ceria-free Cr. The difference in oxidation behavior is mainly attributed to the fact that ceria greatly reduces the growth speed and grain size of Cr2O3 film, and this fine grain-sized Cr2O3 film probably has better high temperature plasticity, i.e. oxide film can relieve parts of compressive stress by means of creeping. XRD and Raman testing results both show the stress declination due to nano-CeO2 application, and their deviation is analyzed concerning to the rare earth effect.
2008, 19(12): 1509-1512
doi: 10.1016/j.cclet.2008.09.031
Abstract:
The sofid-state ECL behavior of a water-insoluble bis-cyclometalated (pq)2Ir(N-phMA) complex is presented, in which pq is a 2-phenylquinoline anion and N-phMA is N-phenyl methacrylamide, a monoanionic bidentate ligand. The MWNTs/(pq)2Ir(N-phMA) film, MWNTs/Ru(bpy)32+ film and (pq)2Ir(N-phMA) directly modified glassy carbon electrode were fabricated; only the MWNTs/(pq)2Ir(N-phMA) film can produce steady ECL in the presence of tri-n-propylamine as a coreactant.
The sofid-state ECL behavior of a water-insoluble bis-cyclometalated (pq)2Ir(N-phMA) complex is presented, in which pq is a 2-phenylquinoline anion and N-phMA is N-phenyl methacrylamide, a monoanionic bidentate ligand. The MWNTs/(pq)2Ir(N-phMA) film, MWNTs/Ru(bpy)32+ film and (pq)2Ir(N-phMA) directly modified glassy carbon electrode were fabricated; only the MWNTs/(pq)2Ir(N-phMA) film can produce steady ECL in the presence of tri-n-propylamine as a coreactant.
2008, 19(12): 1513-1516
doi: 10.1016/j.cclet.2008.09.045
Abstract:
Three possible lower barrier dissociation pathways of the deportonated glyoxylic acid in aqueous solution axe predicated by means of B3LYP and CCSD(T) (single-point) methods. The calculated results suggest that the formation of formate ion is the energetically most favorable process, and that the decomposition reaction is occurring through nucleophilic attack of negatively charged carboxylic oxygen on the a-carbon. This is in good agreement with the proposed mechanisms of the mass spectrometry experiment.
Three possible lower barrier dissociation pathways of the deportonated glyoxylic acid in aqueous solution axe predicated by means of B3LYP and CCSD(T) (single-point) methods. The calculated results suggest that the formation of formate ion is the energetically most favorable process, and that the decomposition reaction is occurring through nucleophilic attack of negatively charged carboxylic oxygen on the a-carbon. This is in good agreement with the proposed mechanisms of the mass spectrometry experiment.
