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2010 Volume 21 Issue 10
2010, 21(10): 1141-1144
doi: 10.1016/j.cclet.2010.06.011
Abstract:
A series of novel 7-(3-aminopyrrolo[3, 4-c]pyrazol-5(2H, 4H, 6H)-yl)quinolone derivatives were designed, synthesized and evaluated for in vitro antibacterial activities. Compounds 6g, 7g and 7h with the potencies similar to those of gemifloxacin, moxifloxacin, gatifloxacin and levofloxacin against Gram-positive organisms, worth further investigation.
A series of novel 7-(3-aminopyrrolo[3, 4-c]pyrazol-5(2H, 4H, 6H)-yl)quinolone derivatives were designed, synthesized and evaluated for in vitro antibacterial activities. Compounds 6g, 7g and 7h with the potencies similar to those of gemifloxacin, moxifloxacin, gatifloxacin and levofloxacin against Gram-positive organisms, worth further investigation.
2010, 21(10): 1145-1148
doi: 10.1016/j.cclet.2010.06.017
Abstract:
The synthesis of a new series of 3-(5-substituted benzimidazol-2-yl)-5-arylisoxazolines (6a-h) was achieved in excellent yields by the condensation of 1-(1H-benzimidazol-2-yl)-3-(substituted phenyl)prop-2-en-1-ones (5a-h) with hydroxylamine at room temperature. These 1-(1H-benzimidazol-2-yl)-3-(substituted phenyl)prop-2-en-1-ones (5a-h) were obtained by the condensation of 2-acetyl benzimidazoles (4a-d) with different aromatic aldehydes, which in turn were obtained by the oxidation of 2-(α-hydroxy)ethyl benzimidazoles (3a-d) prepared by the reaction of o-phenylenediamines (1a-d) with α-hydroxy propionic acid 2. The synthesized compounds were characterized by their IR, 1H NMR and MS analyses. These compounds were screened for their antibacterial and antifungal activity by standard methods and found some of them active.
The synthesis of a new series of 3-(5-substituted benzimidazol-2-yl)-5-arylisoxazolines (6a-h) was achieved in excellent yields by the condensation of 1-(1H-benzimidazol-2-yl)-3-(substituted phenyl)prop-2-en-1-ones (5a-h) with hydroxylamine at room temperature. These 1-(1H-benzimidazol-2-yl)-3-(substituted phenyl)prop-2-en-1-ones (5a-h) were obtained by the condensation of 2-acetyl benzimidazoles (4a-d) with different aromatic aldehydes, which in turn were obtained by the oxidation of 2-(α-hydroxy)ethyl benzimidazoles (3a-d) prepared by the reaction of o-phenylenediamines (1a-d) with α-hydroxy propionic acid 2. The synthesized compounds were characterized by their IR, 1H NMR and MS analyses. These compounds were screened for their antibacterial and antifungal activity by standard methods and found some of them active.
2010, 21(10): 1149-1152
doi: 10.1016/j.cclet.2010.04.012
Abstract:
In pursuit for better antiepileptic drug and the importance of semicarbazones and 2, 5-disubstituted 1, 3, 4-thiadiazoles as anticonvulsant pharmacophore, a series of novel N-({5-[(6-methyl-1-benzofuran-3-yl) methyl]-1, 3, 4-thiadiazol-2-yl}carba-mothioyl)-2/3/4-substitutedbenzamide were designed, synthesized and evaluated for their anticonvulsant activity. The findings of the present studies confirmed that the pharmacophore model with four binding sites is crucial for anticonvuisant activity. Structure-activity relationships among synthesized compounds were also established.
In pursuit for better antiepileptic drug and the importance of semicarbazones and 2, 5-disubstituted 1, 3, 4-thiadiazoles as anticonvulsant pharmacophore, a series of novel N-({5-[(6-methyl-1-benzofuran-3-yl) methyl]-1, 3, 4-thiadiazol-2-yl}carba-mothioyl)-2/3/4-substitutedbenzamide were designed, synthesized and evaluated for their anticonvulsant activity. The findings of the present studies confirmed that the pharmacophore model with four binding sites is crucial for anticonvuisant activity. Structure-activity relationships among synthesized compounds were also established.
2010, 21(10): 1153-1156
doi: 10.1016/j.cclet.2010.03.040
Abstract:
In order to investigate the effect of different C4 linkage moieties on the cytotoxicity of podophyllotoxin derivatives, novel 4-N-and 4-C-substituted 4'-O-demethylepipodophyllotoxin derivatives were designed and synthesized. All the compounds were tested against A549 and MCF-7 tumor cells in vitro, and six compounds showed significant cytotoxicity. The most active compound 9f was superior to GL-331, and exhibited potent cytotoxicity with IC50 value at 10-7 mol/L level.
In order to investigate the effect of different C4 linkage moieties on the cytotoxicity of podophyllotoxin derivatives, novel 4-N-and 4-C-substituted 4'-O-demethylepipodophyllotoxin derivatives were designed and synthesized. All the compounds were tested against A549 and MCF-7 tumor cells in vitro, and six compounds showed significant cytotoxicity. The most active compound 9f was superior to GL-331, and exhibited potent cytotoxicity with IC50 value at 10-7 mol/L level.
2010, 21(10): 1157-1161
doi: 10.1016/j.cclet.2010.04.005
Abstract:
An improved strategy for the synthesis of 3, 3'-(oxy-p-phenylene) bis (2, 4, 5-tdphenylcyclopentadienone) was developed, which includes three steps:Friedel-Crafts reaction, oxidation and condensation. Importantly, the use of KMnO4 made the second step simple and efficient, which has potential application to synthesis of bis (cyclopentadienone)s. The course of oxidation has been confirmed by isolated intermediates.
An improved strategy for the synthesis of 3, 3'-(oxy-p-phenylene) bis (2, 4, 5-tdphenylcyclopentadienone) was developed, which includes three steps:Friedel-Crafts reaction, oxidation and condensation. Importantly, the use of KMnO4 made the second step simple and efficient, which has potential application to synthesis of bis (cyclopentadienone)s. The course of oxidation has been confirmed by isolated intermediates.
2010, 21(10): 1162-1164
doi: 10.1016/j.cclet.2010.05.031
Abstract:
Primary and secondary benzylic alcohols were oxidized to the corresponding carbonyl compounds in good to high yields by environmentally friendly and green oxidant, H2O2 catalyzed by Montmorillonite-K10 supported manganese(Ⅱ) chloride.
Primary and secondary benzylic alcohols were oxidized to the corresponding carbonyl compounds in good to high yields by environmentally friendly and green oxidant, H2O2 catalyzed by Montmorillonite-K10 supported manganese(Ⅱ) chloride.
2010, 21(10): 1165-1166
doi: 10.1016/j.cclet.2010.04.038
Abstract:
A facile approach for the first synthesis of ocimarin, naturally occurring coumarins, was developed by employing a cerium (Ⅲ) chloride heptahydrate-catalyzed Pechmann condensation of phenols and β-keto esters in a solvent-free system as key step, by which ocimarin was achieved by three steps starting from acetylacetic ether and resorcinol with total yield 23.2%. All structures of new compounds were confirmed by IR, 1H NMR and MS.
A facile approach for the first synthesis of ocimarin, naturally occurring coumarins, was developed by employing a cerium (Ⅲ) chloride heptahydrate-catalyzed Pechmann condensation of phenols and β-keto esters in a solvent-free system as key step, by which ocimarin was achieved by three steps starting from acetylacetic ether and resorcinol with total yield 23.2%. All structures of new compounds were confirmed by IR, 1H NMR and MS.
Strontium chloride-catalyzed one-pot synthesis of 4(3H)-quinazolinones under solvent-free conditions
2010, 21(10): 1167-1170
doi: 10.1016/j.cclet.2010.05.021
Abstract:
Strontium chloride was used as an efficient and recyclable catalyst in one-pot condensation of anthranilic acid, ortho esters and amines leading to the formation of 4(3H)-quinazolinone derivatives in good yields at room temperature under solvent-free conditions.
Strontium chloride was used as an efficient and recyclable catalyst in one-pot condensation of anthranilic acid, ortho esters and amines leading to the formation of 4(3H)-quinazolinone derivatives in good yields at room temperature under solvent-free conditions.
2010, 21(10): 1171-1174
doi: 10.1016/j.cclet.2010.06.014
Abstract:
A new practical method for the synthesis of unsymmetrical ureas was achieved by reaction of phenylurea with primary and secondary amines under neutral and mild condition in very good yields. The reaction took place in refluxing dioxane and does not require any catalyst or additives.
A new practical method for the synthesis of unsymmetrical ureas was achieved by reaction of phenylurea with primary and secondary amines under neutral and mild condition in very good yields. The reaction took place in refluxing dioxane and does not require any catalyst or additives.
2010, 21(10): 1175-1179
doi: 10.1016/j.cclet.2010.06.013
Abstract:
This report describes triethylammonium acetate (TEAA) ionic liquid catalyzed one pot synthesis of 6-amino-4-aryl-5-cyano-3-methyl-1-phenyl-1, 4-dihydropyrano[2, 3-c]pyrazoles by the reaction of aromatic aldehyde, malononitrile and 3-methyl-1-phenyl-2-pyrazolin-5-one at room temperature. TEAA plays dual role as reaction media and catalyst. It can also be easily recovered and reused in several runs. TEAA provides greener reaction protocol to present methodology which obviates the need of organic solvents, expensive and toxic catalyst.
This report describes triethylammonium acetate (TEAA) ionic liquid catalyzed one pot synthesis of 6-amino-4-aryl-5-cyano-3-methyl-1-phenyl-1, 4-dihydropyrano[2, 3-c]pyrazoles by the reaction of aromatic aldehyde, malononitrile and 3-methyl-1-phenyl-2-pyrazolin-5-one at room temperature. TEAA plays dual role as reaction media and catalyst. It can also be easily recovered and reused in several runs. TEAA provides greener reaction protocol to present methodology which obviates the need of organic solvents, expensive and toxic catalyst.
2010, 21(10): 1180-1182
doi: 10.1016/j.cclet.2010.05.018
Abstract:
An efficient procedure is reported for the synthesis of 3, 3, 6, 6-tetramethyl-9-aryl-1, 8-dioxooctahydroxanthenes using a one-pot condensation of arylaldehydes and 5, 5-dimethyl-1, 3-cyclohexandione in the presence of DABCO-bromine (TDB) as an acid catalyst. To the best of our knowledge this is the first time that DABCO-bromine is used as an acid catalyst in aqueous media for this type of reaction. This method provides several advantages such as use of water as solvent, easy and clean synthesis, simple work up and versatility.
An efficient procedure is reported for the synthesis of 3, 3, 6, 6-tetramethyl-9-aryl-1, 8-dioxooctahydroxanthenes using a one-pot condensation of arylaldehydes and 5, 5-dimethyl-1, 3-cyclohexandione in the presence of DABCO-bromine (TDB) as an acid catalyst. To the best of our knowledge this is the first time that DABCO-bromine is used as an acid catalyst in aqueous media for this type of reaction. This method provides several advantages such as use of water as solvent, easy and clean synthesis, simple work up and versatility.
2010, 21(10): 1183-1186
doi: 10.1016/j.cclet.2010.06.012
Abstract:
Sodium dihydrogen phosphate (NaH2PO4) efficiently catalyzes the condensation reaction of benzil, aldehydes, amines and ammonium acetate in a four-component reaction under solvent-free conditions. The reaction proceeds rapidly and affords the corresponding tetra-substituted imidazoles in high yields. Also an efficient route was developed for the synthesis of tri-substituted imidazoles from condensation of benzil, aldehydes and ammonium acetate using NaH2PO4.
Sodium dihydrogen phosphate (NaH2PO4) efficiently catalyzes the condensation reaction of benzil, aldehydes, amines and ammonium acetate in a four-component reaction under solvent-free conditions. The reaction proceeds rapidly and affords the corresponding tetra-substituted imidazoles in high yields. Also an efficient route was developed for the synthesis of tri-substituted imidazoles from condensation of benzil, aldehydes and ammonium acetate using NaH2PO4.
2010, 21(10): 1187-1190
doi: 10.1016/j.cclet.2010.04.031
Abstract:
A mild and efficient method for the conversion of alcohols to their corresponding methoxymethyl ethers and acetates using benzyltriphenylphosphonium tribromide (BTPTB) as catalyst is described. All reactions were performed under completely heterogeneous reaction conditions in good to high yields.
A mild and efficient method for the conversion of alcohols to their corresponding methoxymethyl ethers and acetates using benzyltriphenylphosphonium tribromide (BTPTB) as catalyst is described. All reactions were performed under completely heterogeneous reaction conditions in good to high yields.
2010, 21(10): 1191-1194
doi: 10.1016/j.cclet.2010.04.037
Abstract:
An environmentally benign and highly efficient one-pot preparation of α-aminophosphonates under solvent-free conditions was developed. By employing this method, 5-aminophosphonate substituted pyrimidine nucleosides were synthesized in good to excellent yields starting from 5-formyl-2'-deoxyuridine, aniline and dimethylphosphite.
An environmentally benign and highly efficient one-pot preparation of α-aminophosphonates under solvent-free conditions was developed. By employing this method, 5-aminophosphonate substituted pyrimidine nucleosides were synthesized in good to excellent yields starting from 5-formyl-2'-deoxyuridine, aniline and dimethylphosphite.
2010, 21(10): 1195-1198
doi: 10.1016/j.cclet.2010.05.032
Abstract:
This letter presents excited state intramolecular proton transfer (ESIPT) of new conjugated derivatives containing hydroxy and imino groups. ESIPT occurrence in one photon process is confirmed by well-separated emission band for the derivatives. Twophoton absorption (TPA) induced ESIPT emission has been determined by Ti:sapphire femtosecond laser tuning from 700 nm to 800 nm at the internals of 20 nm.
This letter presents excited state intramolecular proton transfer (ESIPT) of new conjugated derivatives containing hydroxy and imino groups. ESIPT occurrence in one photon process is confirmed by well-separated emission band for the derivatives. Twophoton absorption (TPA) induced ESIPT emission has been determined by Ti:sapphire femtosecond laser tuning from 700 nm to 800 nm at the internals of 20 nm.
2010, 21(10): 1199-1202
doi: 10.1016/j.cclet.2010.04.036
Abstract:
The synthesis of mono-and bis-1, 3-diazabicyclo[3.1. 0]hex-3-ene derivatives with indole ring and p-phenylene spacer, which behave as photochromic materials, is reported. The structure-photochromic behavior relationship (SPBR) of the synthesized compounds has been analyzed.
The synthesis of mono-and bis-1, 3-diazabicyclo[3.1. 0]hex-3-ene derivatives with indole ring and p-phenylene spacer, which behave as photochromic materials, is reported. The structure-photochromic behavior relationship (SPBR) of the synthesized compounds has been analyzed.
2010, 21(10): 1203-1205
doi: 10.1016/j.cclet.2010.05.023
Abstract:
A novel chromone, named chaetoaurin (1), along with six known chromone derivatives (2-7), was isolated from the ethyl acetate extract of a solid-state fermented culture of Chaetomium aureus. Their structures were elucidated by extensive spectral analysis. All of these compounds were reported from C. aureus for the first time.
A novel chromone, named chaetoaurin (1), along with six known chromone derivatives (2-7), was isolated from the ethyl acetate extract of a solid-state fermented culture of Chaetomium aureus. Their structures were elucidated by extensive spectral analysis. All of these compounds were reported from C. aureus for the first time.
2010, 21(10): 1206-1208
doi: 10.1016/j.cclet.2010.05.034
Abstract:
Gibberellin A4 is effectively separated from mixture of gibberellin A4 and its analogue gibberellin A7, in the form of its crystalline complex with N, N, N', N'-tetramethylethylenediamine. After removing the tetramethylethylenediamine from the crystal by dilute HCl, gibberellin A4 is obtained a purity of 98.1% and a yield of 72.7%.
Gibberellin A4 is effectively separated from mixture of gibberellin A4 and its analogue gibberellin A7, in the form of its crystalline complex with N, N, N', N'-tetramethylethylenediamine. After removing the tetramethylethylenediamine from the crystal by dilute HCl, gibberellin A4 is obtained a purity of 98.1% and a yield of 72.7%.
2010, 21(10): 1209-1212
doi: 10.1016/j.cclet.2010.06.016
Abstract:
Two new steroidal alkaloids, veraussines A(1) and B(2) were isolated from the roots and rhizomes of Veratrum nigrum var. ussuriense. Their structures were determined as N-(ethoxycarbonyl)-1α, 2β, 3α, 15α-tetrahydroxy-5β-jervanin-12-en-11-one (1) and N-(methoxycarbonyl)-1α, 2β, 3α, 15α-tetrahydroxy-5β-jervanin-12-en-11-one(2)by spectroscopic analysis.
Two new steroidal alkaloids, veraussines A(1) and B(2) were isolated from the roots and rhizomes of Veratrum nigrum var. ussuriense. Their structures were determined as N-(ethoxycarbonyl)-1α, 2β, 3α, 15α-tetrahydroxy-5β-jervanin-12-en-11-one (1) and N-(methoxycarbonyl)-1α, 2β, 3α, 15α-tetrahydroxy-5β-jervanin-12-en-11-one(2)by spectroscopic analysis.
2010, 21(10): 1213-1215
doi: 10.1016/j.cclet.2010.06.015
Abstract:
A new brominated C15-acetogenin, namely, laurenidificin, was isolated from the marine red alga Laurencia nidifica. Its structure was determined on the basis of spectroscopic methods.
A new brominated C15-acetogenin, namely, laurenidificin, was isolated from the marine red alga Laurencia nidifica. Its structure was determined on the basis of spectroscopic methods.
2010, 21(10): 1216-1218
doi: 10.1016/j.cclet.2010.06.010
Abstract:
One new triterpene saponin was isolated from Panax japonicus C. A. Meyer var major(Burk.)C. Y. Wu et K. M. Feng, and established as oleanolic acid 3-O-[β-D-glucopyranosyl-(1→2)-β-D-glucuronopyranosyl-6'-O-n-butyl ester]which showed moderate antitumor activities against the A2780 cells and OVCAR-3 cells. Its structure was established by means of spectral data, particularly NMR, including HSQC and HMBC techniques.
One new triterpene saponin was isolated from Panax japonicus C. A. Meyer var major(Burk.)C. Y. Wu et K. M. Feng, and established as oleanolic acid 3-O-[β-D-glucopyranosyl-(1→2)-β-D-glucuronopyranosyl-6'-O-n-butyl ester]which showed moderate antitumor activities against the A2780 cells and OVCAR-3 cells. Its structure was established by means of spectral data, particularly NMR, including HSQC and HMBC techniques.
Direct determination of trace amounts of acetic acid using a novel ambient glow discharge ion source
2010, 21(10): 1219-1222
doi: 10.1016/j.cclet.2010.05.008
Abstract:
A novel ambient glow discharge ion source with improved line-cylinder electrodes is put forward and designed in this paper. The diameters of inner and outer electrodes are 0.16 and 4 mm respectively. With a special assembly method, a perfect coaxiality of the two electrodes is obtained. From the gas discharge experiment, it can be seen that the discharge can stably work in normal glow discharge mode. The operating currents of the ion source are in an order of milliamperes and can generate a much larger number and wider variety of reagent ions. The MS experiment shows that the ion source has higher detection sensitivity.
A novel ambient glow discharge ion source with improved line-cylinder electrodes is put forward and designed in this paper. The diameters of inner and outer electrodes are 0.16 and 4 mm respectively. With a special assembly method, a perfect coaxiality of the two electrodes is obtained. From the gas discharge experiment, it can be seen that the discharge can stably work in normal glow discharge mode. The operating currents of the ion source are in an order of milliamperes and can generate a much larger number and wider variety of reagent ions. The MS experiment shows that the ion source has higher detection sensitivity.
2010, 21(10): 1223-1226
doi: 10.1016/j.cclet.2010.04.016
Abstract:
A method using HPLC-DAD coupled with second-order calibration was developed to simultaneously determine metronidazole and tinidazole in plasma samples in this paper. The second-order calibration method based on APTLD (alternating penalty trilinear decomposition) algorithm was proposed to analyze the three-way HPLC-DAD data from both standard and prediction samples, which makes it possible that calibration can be performed even in the presence of unknown interferences with a simple and green chromatographic condition and short analysis time. The results showed that good recoveries were obtained although the chromatographic and spectral profiles of the analytes of interest as well as background were partially overlapped with each other in plasma samples.
A method using HPLC-DAD coupled with second-order calibration was developed to simultaneously determine metronidazole and tinidazole in plasma samples in this paper. The second-order calibration method based on APTLD (alternating penalty trilinear decomposition) algorithm was proposed to analyze the three-way HPLC-DAD data from both standard and prediction samples, which makes it possible that calibration can be performed even in the presence of unknown interferences with a simple and green chromatographic condition and short analysis time. The results showed that good recoveries were obtained although the chromatographic and spectral profiles of the analytes of interest as well as background were partially overlapped with each other in plasma samples.
2010, 21(10): 1227-1230
doi: 10.1016/j.cclet.2010.05.007
Abstract:
Gold nanoparticles (GNPs) have been widely used as probes and nanomaterials in certain biological and biomedical fields thanks to its special physical and chemical properties. However, it is still difficult to characterize GNPs-bioconjugates in solution, which has greatly limited further bioapplications of GNPs. In this study, we reported a single particle method for characterizing GNPsbiomolecules in solution using resonance light scattering correlation spectroscopy (RLSCS). The interaction of GNPs with bovine serum albumin (BSA) and thiol-modified oligonucletides were investigated.
Gold nanoparticles (GNPs) have been widely used as probes and nanomaterials in certain biological and biomedical fields thanks to its special physical and chemical properties. However, it is still difficult to characterize GNPs-bioconjugates in solution, which has greatly limited further bioapplications of GNPs. In this study, we reported a single particle method for characterizing GNPsbiomolecules in solution using resonance light scattering correlation spectroscopy (RLSCS). The interaction of GNPs with bovine serum albumin (BSA) and thiol-modified oligonucletides were investigated.
2010, 21(10): 1231-1234
doi: 10.1016/j.cclet.2010.04.040
Abstract:
A high-performance capillary electrophoresis with amperometry detection method (CE-AD) has been developed for the analysis of flavonoids and anthraquinones (emodin, kaempferol, apigenin, luteolin and rhein) in chrysanthemum. Under optimum conditions, these five analytes were base-line separated within 17 min using a borate-phosphate running buffer (1.5×10-2mol/L borate-3×10-2 mol/L phosphate running buffer, pH 9.0) at a working potential of +0.90 V (vs. SCE) and a separation voltage of 19 kV. The linear relationship between concentration and current response was obtained with detection limits (S/N=3) ranging from 1.0×10-7 to 2.1×10-7 g/mL for all analytes. This proposed method was successfully used in the analysis of four kinds of chrysanthemum with relatively simple extraction procedures, the assay results were satisfactory.
A high-performance capillary electrophoresis with amperometry detection method (CE-AD) has been developed for the analysis of flavonoids and anthraquinones (emodin, kaempferol, apigenin, luteolin and rhein) in chrysanthemum. Under optimum conditions, these five analytes were base-line separated within 17 min using a borate-phosphate running buffer (1.5×10-2mol/L borate-3×10-2 mol/L phosphate running buffer, pH 9.0) at a working potential of +0.90 V (vs. SCE) and a separation voltage of 19 kV. The linear relationship between concentration and current response was obtained with detection limits (S/N=3) ranging from 1.0×10-7 to 2.1×10-7 g/mL for all analytes. This proposed method was successfully used in the analysis of four kinds of chrysanthemum with relatively simple extraction procedures, the assay results were satisfactory.
2010, 21(10): 1235-1238
doi: 10.1016/j.cclet.2010.04.007
Abstract:
Tetracycline selective electrode using molecularly imprinted polymer particles as quasi-ionophore was constructed the first time, and its performance was carefully characterized. Due to the specific recognition of tetracycline by the particles, the selectivity coefficients for routine interferences were less than 10-4. Benefited from the absence of tetracycline in the sensitive membrane and the optimized composition of the inner filling solution, the limit of detection of the electrode was reduced to about 2.5×10-8 mol/L. It exhibited a good electrode slope 57.6 mV/decade near the theoretical Nernstian one, with a wide linear working range from 6.0×10-8 to 1.0×10-3 mol/L. The fabricated electrode should be used in pH 2-4, response time of which was less than 200 s when the concentration of tetracycline was higher than 1.0×10-6 mol/L and no more than 30 min at the concentration of 1.0×10-8 mol/L.
Tetracycline selective electrode using molecularly imprinted polymer particles as quasi-ionophore was constructed the first time, and its performance was carefully characterized. Due to the specific recognition of tetracycline by the particles, the selectivity coefficients for routine interferences were less than 10-4. Benefited from the absence of tetracycline in the sensitive membrane and the optimized composition of the inner filling solution, the limit of detection of the electrode was reduced to about 2.5×10-8 mol/L. It exhibited a good electrode slope 57.6 mV/decade near the theoretical Nernstian one, with a wide linear working range from 6.0×10-8 to 1.0×10-3 mol/L. The fabricated electrode should be used in pH 2-4, response time of which was less than 200 s when the concentration of tetracycline was higher than 1.0×10-6 mol/L and no more than 30 min at the concentration of 1.0×10-8 mol/L.
2010, 21(10): 1239-1242
doi: 10.1016/j.cclet.2010.05.022
Abstract:
A mixed self-assembled monolayers (SAMs) of thioctic acid (T-COOH) and thioctic acid amide (T-NH2) were used to immobilize tyrosinase for fabricating biosensor. The results showed that the mixed SAMs prepared from solution at the ratio of 1:4provided an excellent microenvironment for enzymatic reaction between tyrosinase and substrate. The biosensor exhibited a fast response and high sensitivity for sensing substrate.
A mixed self-assembled monolayers (SAMs) of thioctic acid (T-COOH) and thioctic acid amide (T-NH2) were used to immobilize tyrosinase for fabricating biosensor. The results showed that the mixed SAMs prepared from solution at the ratio of 1:4provided an excellent microenvironment for enzymatic reaction between tyrosinase and substrate. The biosensor exhibited a fast response and high sensitivity for sensing substrate.
2010, 21(10): 1243-1246
doi: 10.1016/j.cclet.2010.05.020
Abstract:
A novel potassium ions sensor based on mode-filtered light detection was reported. The analyzer was consisting of an optical fiber immobilized with a dye of bromocresol green and a fused-silica capillary. It was found that mode-filtered light intensity decreased with the concentration of potassium ions and a linear detection range of 0.25-20 mmol/L(R2=0.9977) was obtained with a detection limit of 9×10-5 mol/L as well as fast response, good reproducibility and reversibility in the working concentration range.
A novel potassium ions sensor based on mode-filtered light detection was reported. The analyzer was consisting of an optical fiber immobilized with a dye of bromocresol green and a fused-silica capillary. It was found that mode-filtered light intensity decreased with the concentration of potassium ions and a linear detection range of 0.25-20 mmol/L(R2=0.9977) was obtained with a detection limit of 9×10-5 mol/L as well as fast response, good reproducibility and reversibility in the working concentration range.
2010, 21(10): 1247-1250
doi: 10.1016/j.cclet.2010.04.017
Abstract:
A new fluorinated poly (ether amide) bearing xanthene group was prepared from 9, 9-bis[4-(2-trifluoromethyl-4-aminophenox-y) phenyl]xanthene (BTFAPX) with 9, 9-bis[4-(4-carboxyphenoxy) phenyllxanthene(BCAPX)in the presence of triphenyl phos-phate and pyridine (Py). The polymer had the weight-average molecular weight (Mw) of 69, 000 and number-average molecular weight (Mn) of 39, 000, showed the glass transition temperature (Tg) of 267℃, 5% weight loss temperature(Td5)over 460℃ both in N2 and air, and char yield of 62% at 800℃ in N2. This polymer was amorphous and readily soluble in amide-type solvents such as N, N-dimethylacetamide (DMAc), and even in m-cressol, Py and tetrahydrofuran (THF) at room temperature, and exhibited tensile strength of 74 MPa, elongation at break of 6%, tensile moduli of 2.2 GPa. The polymer had low dielectric constant of 3.69 (100 Hz), low moisture absorption of 0.56%, and high transparency with an ultraviolet-visible absorption cut-off wavelength at 334 nm.
A new fluorinated poly (ether amide) bearing xanthene group was prepared from 9, 9-bis[4-(2-trifluoromethyl-4-aminophenox-y) phenyl]xanthene (BTFAPX) with 9, 9-bis[4-(4-carboxyphenoxy) phenyllxanthene(BCAPX)in the presence of triphenyl phos-phate and pyridine (Py). The polymer had the weight-average molecular weight (Mw) of 69, 000 and number-average molecular weight (Mn) of 39, 000, showed the glass transition temperature (Tg) of 267℃, 5% weight loss temperature(Td5)over 460℃ both in N2 and air, and char yield of 62% at 800℃ in N2. This polymer was amorphous and readily soluble in amide-type solvents such as N, N-dimethylacetamide (DMAc), and even in m-cressol, Py and tetrahydrofuran (THF) at room temperature, and exhibited tensile strength of 74 MPa, elongation at break of 6%, tensile moduli of 2.2 GPa. The polymer had low dielectric constant of 3.69 (100 Hz), low moisture absorption of 0.56%, and high transparency with an ultraviolet-visible absorption cut-off wavelength at 334 nm.
2010, 21(10): 1251-1254
doi: 10.1016/j.cclet.2010.04.018
Abstract:
This paper describes a triple-transforming gel system(gel-sol-gel')for the first time, which is a thermo-responsive and multicomponent organogel prepared by β-cyclodextrin (β-CD), diphenylamine(DPA)and lithium chloride (LiCl) in N, N-dimethylacetamide (DMAC) in a suitable proportion based on the supramolecular interactions. In the triple-transforming gel system, a gel (gel A) could be formed by β-CD, DPA and LiCl in DMAC at room temperature based on stirring, then the gel could transform into a clear solution based on heating, and then the other gel (gel B) can be formed at a relatively high temperature(Tgel, the gelation temperature by heating). The two gel states in the triple-transforming gel system have different microstructures. This gel system was characterized by OM, SEM, IR and rheology.
This paper describes a triple-transforming gel system(gel-sol-gel')for the first time, which is a thermo-responsive and multicomponent organogel prepared by β-cyclodextrin (β-CD), diphenylamine(DPA)and lithium chloride (LiCl) in N, N-dimethylacetamide (DMAC) in a suitable proportion based on the supramolecular interactions. In the triple-transforming gel system, a gel (gel A) could be formed by β-CD, DPA and LiCl in DMAC at room temperature based on stirring, then the gel could transform into a clear solution based on heating, and then the other gel (gel B) can be formed at a relatively high temperature(Tgel, the gelation temperature by heating). The two gel states in the triple-transforming gel system have different microstructures. This gel system was characterized by OM, SEM, IR and rheology.
2010, 21(10): 1255-1258
doi: 10.1016/j.cclet.2010.04.032
Abstract:
A novel biodegradable copolymer, poly (5, 5-dibromomethyltrimethylene carbonate-co-ε-caprolactone)(poly(DBTC-co-CL)) with pendant bromine groups, was synthesized via ring-opening polymerization(ROP)of ε-caprolactone(CL)and 5, 5-dibromomethyltrimethylene carbonate (DBTC) using stannous octoate (Sn(Oct)2) as catalyst. Then the pendant bromine groups were completely converted into azide form, which permitted "click" reaction with alkyne-terminated polyethylene (A-PEG) by Huisgen 1, 3-dipolar cycloadditions preparing biodegradable amphiphilic poly (DTC-co-CL)-g-PEG graft copolymer. The graft copolymer was characterized by nuclear magnetic resonance(NMR)and size-exclusion chromatography (SEC).
A novel biodegradable copolymer, poly (5, 5-dibromomethyltrimethylene carbonate-co-ε-caprolactone)(poly(DBTC-co-CL)) with pendant bromine groups, was synthesized via ring-opening polymerization(ROP)of ε-caprolactone(CL)and 5, 5-dibromomethyltrimethylene carbonate (DBTC) using stannous octoate (Sn(Oct)2) as catalyst. Then the pendant bromine groups were completely converted into azide form, which permitted "click" reaction with alkyne-terminated polyethylene (A-PEG) by Huisgen 1, 3-dipolar cycloadditions preparing biodegradable amphiphilic poly (DTC-co-CL)-g-PEG graft copolymer. The graft copolymer was characterized by nuclear magnetic resonance(NMR)and size-exclusion chromatography (SEC).
Preparation of sulphonate-containing core/shell latex particles via seeded emulsion copolymerization
2010, 21(10): 1259-1262
doi: 10.1016/j.cclet.2010.04.019
Abstract:
In this study, P(St-MAA)seed latex particles were first prepared via soap-free emulsion polymerization of styrene(St)and methacrylic acid (MAA), then the seed particles were allowed to swell with St at room temperature, and the P(St-MAA)/P(St-NaSS) core/shell latex particles were then synthesized via seeded emulsion copolymerization of St and sodium styrene sulphonate (NaSS) using AIBN as initiator in the presence of N, N'-methylenebisacrylamide (BAA, water-soluble crosslinker). Results showed that the polymerization could be carried out smoothly when the ratio of BAA to total monomers was less than 3 mol%, the narrow dispersed P(St-MAA)seed particles with the diameter of 150 nm and the P(St-MAA)/P(St-NaSS)core/shell latexes with the particle size of about 200 nm were synthesized. When the 25/75 mole ratio of NaSS/(St+MAA)and 2 mol% of BAA were used in the seeded emulsion polymerization, the resulted P(St-MAA)/P(St-NaSS) latex product showed a low weight loss after water extraction, and the NaSS unit content in the whole particle and in the shell reached 11.7 mol% and 34.6 mol%, respectively.
In this study, P(St-MAA)seed latex particles were first prepared via soap-free emulsion polymerization of styrene(St)and methacrylic acid (MAA), then the seed particles were allowed to swell with St at room temperature, and the P(St-MAA)/P(St-NaSS) core/shell latex particles were then synthesized via seeded emulsion copolymerization of St and sodium styrene sulphonate (NaSS) using AIBN as initiator in the presence of N, N'-methylenebisacrylamide (BAA, water-soluble crosslinker). Results showed that the polymerization could be carried out smoothly when the ratio of BAA to total monomers was less than 3 mol%, the narrow dispersed P(St-MAA)seed particles with the diameter of 150 nm and the P(St-MAA)/P(St-NaSS)core/shell latexes with the particle size of about 200 nm were synthesized. When the 25/75 mole ratio of NaSS/(St+MAA)and 2 mol% of BAA were used in the seeded emulsion polymerization, the resulted P(St-MAA)/P(St-NaSS) latex product showed a low weight loss after water extraction, and the NaSS unit content in the whole particle and in the shell reached 11.7 mol% and 34.6 mol%, respectively.
2010, 21(10): 1263-1266
doi: 10.1016/j.cclet.2010.05.017
Abstract:
Two pyrazine-containing macrocyclic polyazomethines 2 and 3 were synthesized by direct[2+2]and[3+3]condensation reactions between 2, 2'-[pyrazine-2, 3-diylbis(oxy)]dibenzaldehyde (1) and hydrazine. Both 2 and 3 were characterized by NMR, HRMS, and their structures were determined via X-ray crystal diffraction studies.
Two pyrazine-containing macrocyclic polyazomethines 2 and 3 were synthesized by direct[2+2]and[3+3]condensation reactions between 2, 2'-[pyrazine-2, 3-diylbis(oxy)]dibenzaldehyde (1) and hydrazine. Both 2 and 3 were characterized by NMR, HRMS, and their structures were determined via X-ray crystal diffraction studies.
