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2009 Volume 20 Issue 12
2009, 20(12): 1393-1396
doi: 10.1016/j.cclet.2009.06.040
Abstract:
Four new chiral 1,2,3,4-tetrahydroisoquinoline-derived β-amino alcohols were synthesized from commercially available L-DOPA.These ligands were evaluated in the asymmetric addition of diethylzinc to benzaldehydes and showed different catalytic activities (up to 86% ee).The solvent played an important role in the enantioselective process.The transition state models were proposed to explain the reversion of the product configuration.
Four new chiral 1,2,3,4-tetrahydroisoquinoline-derived β-amino alcohols were synthesized from commercially available L-DOPA.These ligands were evaluated in the asymmetric addition of diethylzinc to benzaldehydes and showed different catalytic activities (up to 86% ee).The solvent played an important role in the enantioselective process.The transition state models were proposed to explain the reversion of the product configuration.
2009, 20(12): 1397-1399
doi: 10.1016/j.cclet.2009.06.036
Abstract:
Sitagliptin is the first new anti-diabetic drug in DPP-IV inhibitor class.The general synthesis of sitagliptin is by coupling of the β-amino acid fragment with the heterocycle fragment.Though the specific β-amino acid can be easily made from the corresponding R-amino acid by Arndt-Eistert homologation, the optically pure precursor R-amino acid is difficult to prepare.We herein reported a practical protocol to make the trifluorophenyl substituted R-amino acid 4 in >99.9% ee and 40.3% yield by the enzymatic resolution employing enantioselective hydrolysis and a general separation procedure.This protocol requires only cheap starting materials and friendly reaction condition.The procedure not only allows people to prepare the drug substance, but also provides an alternative method for prepareing the rare a-amino acid and the subsequent β-amino acid.
Sitagliptin is the first new anti-diabetic drug in DPP-IV inhibitor class.The general synthesis of sitagliptin is by coupling of the β-amino acid fragment with the heterocycle fragment.Though the specific β-amino acid can be easily made from the corresponding R-amino acid by Arndt-Eistert homologation, the optically pure precursor R-amino acid is difficult to prepare.We herein reported a practical protocol to make the trifluorophenyl substituted R-amino acid 4 in >99.9% ee and 40.3% yield by the enzymatic resolution employing enantioselective hydrolysis and a general separation procedure.This protocol requires only cheap starting materials and friendly reaction condition.The procedure not only allows people to prepare the drug substance, but also provides an alternative method for prepareing the rare a-amino acid and the subsequent β-amino acid.
2009, 20(12): 1400-1404
doi: 10.1016/j.cclet.2009.07.007
Abstract:
The efficient, green, facile, mild and straightforward conversion procedure for the oxidation of cyclic ketones to lactones at room temperature utilizing potassium peroxydisulfate (K2S 2O8) in acidic media is satisfactory to high yields without using traditional chlorinated solvents is reported.This oxidative reagent is cheap and friendly environmental procedure for industrial purposes than use of organic peracids.
The efficient, green, facile, mild and straightforward conversion procedure for the oxidation of cyclic ketones to lactones at room temperature utilizing potassium peroxydisulfate (K2S 2O8) in acidic media is satisfactory to high yields without using traditional chlorinated solvents is reported.This oxidative reagent is cheap and friendly environmental procedure for industrial purposes than use of organic peracids.
2009, 20(12): 1405-1407
doi: 10.1016/j.cclet.2009.06.019
Abstract:
The efficient synthesis of N-(diphenylmethylene) glycine alkyl esters was achieved for the first microwave irradiation under solvent-free condition, using PEG or quaternary ammonium salts as phase transfer catalysts (PTCs).Under the optimum conditions,N-(diphenylmethylene) glycine alkyl esters were obtained in excellent yields in most cases.
The efficient synthesis of N-(diphenylmethylene) glycine alkyl esters was achieved for the first microwave irradiation under solvent-free condition, using PEG or quaternary ammonium salts as phase transfer catalysts (PTCs).Under the optimum conditions,N-(diphenylmethylene) glycine alkyl esters were obtained in excellent yields in most cases.
2009, 20(12): 1408-1410
doi: 10.1016/j.cclet.2009.06.037
Abstract:
A simple and efficient procedure for the synthesis of substituted benzothiazoles through condensation of 2-aminothiophenol with aromatic aldehydes in the presence of H 2O2/HCl system in ethanol at room temperature is described.The target compounds have been characterized by 1H NMR,13C NMR, IR and MS.Short reaction time, easy and quick isolation of the products, and excellent yields are the main advantages of this procedure.
A simple and efficient procedure for the synthesis of substituted benzothiazoles through condensation of 2-aminothiophenol with aromatic aldehydes in the presence of H 2O2/HCl system in ethanol at room temperature is described.The target compounds have been characterized by 1H NMR,13C NMR, IR and MS.Short reaction time, easy and quick isolation of the products, and excellent yields are the main advantages of this procedure.
2009, 20(12): 1411-1444
doi: 10.1016/j.cclet.2009.06.021
Abstract:
Oxone (3.5 mol%) was found to be an effective catalyst for the condensation reactions of indoles with aldehydes to afford bisindolylmethanes in good to excellent yields within 10-30 min.The method is simple and economic.The catalyst is found to be recyclable.
Oxone (3.5 mol%) was found to be an effective catalyst for the condensation reactions of indoles with aldehydes to afford bisindolylmethanes in good to excellent yields within 10-30 min.The method is simple and economic.The catalyst is found to be recyclable.
2009, 20(12): 1415-1418
doi: 10.1016/j.cclet.2009.06.033
Abstract:
We have presented the synthesis and characterization of three new bromo substituted stilbene derivatives, p-3,4,5-trimethoxy-p'-2,3,4,5,6-pentabromo st abromo stilbene(C1), p-N,N-dimethylamino-p'-2,3,4,5,6-pentabromo stilbene (C2) and 2013/5/18 23:53 p-N,N-diphenylamino-p'-2,3,4,5,6-pentabromo stilbene (C3) in this letter.The UV/vis absorption and photoluminescence were investigated in various solvents.The maximal absorption wavelength of C1 exhibited blue-shift to those of C2 and C3 in different solvents.No florescence emission could be detected for these compounds at room temperature.Singlet oxygen could be efficiently produced with thesesensitizers under near-ultraviolet and visible light irradiation.
We have presented the synthesis and characterization of three new bromo substituted stilbene derivatives, p-3,4,5-trimethoxy-p'-2,3,4,5,6-pentabromo st abromo stilbene(C1), p-N,N-dimethylamino-p'-2,3,4,5,6-pentabromo stilbene (C2) and 2013/5/18 23:53 p-N,N-diphenylamino-p'-2,3,4,5,6-pentabromo stilbene (C3) in this letter.The UV/vis absorption and photoluminescence were investigated in various solvents.The maximal absorption wavelength of C1 exhibited blue-shift to those of C2 and C3 in different solvents.No florescence emission could be detected for these compounds at room temperature.Singlet oxygen could be efficiently produced with thesesensitizers under near-ultraviolet and visible light irradiation.
2009, 20(12): 1419-1422
doi: 10.1016/j.cclet.2009.06.034
Abstract:
In this paper, the synthesis and characterization of a triarylpyrazoline modified four-H-bonded molecular duplex are described.Its molecular structure has been confirmed by 1H NMR and ESI-MS.The duplex emits strong pure blue light peaking at 448 and 452 nm under UV photoexcitation in solution and solid state, respectively, and its relative photoluminescence quantum efficiency in solution is determined as 0.778 using quinine sulfate as reference.In concentration of >40 mmol/L, the duplex can gelate DMSO,and the organogel formed shows good pure blue photoluminescence too.This novel duplex, for its well-defined structure andefficient photoluminescence property, is a prospective candidate for pure blue electroluminescent emitter.
In this paper, the synthesis and characterization of a triarylpyrazoline modified four-H-bonded molecular duplex are described.Its molecular structure has been confirmed by 1H NMR and ESI-MS.The duplex emits strong pure blue light peaking at 448 and 452 nm under UV photoexcitation in solution and solid state, respectively, and its relative photoluminescence quantum efficiency in solution is determined as 0.778 using quinine sulfate as reference.In concentration of >40 mmol/L, the duplex can gelate DMSO,and the organogel formed shows good pure blue photoluminescence too.This novel duplex, for its well-defined structure andefficient photoluminescence property, is a prospective candidate for pure blue electroluminescent emitter.
2009, 20(12): 1423-1426
doi: 10.1016/j.cclet.2009.06.022
Abstract:
The trimeric phenylenevinylene with the symmetrical chiral end-groups (ChTPV) was synthesized.The liquid crystalline and luminescent properties of the ChTPV have been studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM), absorption and photoluminescence spectra.The results indicated that the ChTPV exhibits mesophase over a wide temperature range and a typical optical texture of smectic phase.In contrast with the spectra of the solution, that of the film showed blue-shift in maximal absorption and red-shift in maximal emission due to H-type aggregation with parallel alignment of the TPV transition dipole moment.
The trimeric phenylenevinylene with the symmetrical chiral end-groups (ChTPV) was synthesized.The liquid crystalline and luminescent properties of the ChTPV have been studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM), absorption and photoluminescence spectra.The results indicated that the ChTPV exhibits mesophase over a wide temperature range and a typical optical texture of smectic phase.In contrast with the spectra of the solution, that of the film showed blue-shift in maximal absorption and red-shift in maximal emission due to H-type aggregation with parallel alignment of the TPV transition dipole moment.
2009, 20(12): 1427-1430
doi: 10.1016/j.cclet.2009.06.015
Abstract:
The novel and facile one-pot method for sulfonyloxylactonization of alkenoic acids was reported:when (diacetoxyiodo)-benzene, various 4-pentenoic acids or 5-hexenoic acid and sulfonic acids were mixed in CH 2Cl2 at room temperature,sulfonyloxylactons were obtained in good to excellent yields in short times, some had two diastereoisomers.
The novel and facile one-pot method for sulfonyloxylactonization of alkenoic acids was reported:when (diacetoxyiodo)-benzene, various 4-pentenoic acids or 5-hexenoic acid and sulfonic acids were mixed in CH 2Cl2 at room temperature,sulfonyloxylactons were obtained in good to excellent yields in short times, some had two diastereoisomers.
2009, 20(12): 1431-1434
doi: 10.1016/j.cclet.2009.07.022
Abstract:
In order to find novel synthetic antitumor agents with superior cytotoxicity and overcoming multidrug resistance, a novel series of 4β-N-substituted podophyllotoxin derivatives were synthesized and evaluated as potential antitumor agents.Seven novel podophyllotoxin derivatives were synthesized by linking 4β-amino-4-deoxypodophyllotoxin with N-substituted 5-methylindol-3-yl-glyoxyl chlorides and tested against K562 and K562/A02 using SRB methods in vitro, KB and KBV using MTT methods in vitro.
In order to find novel synthetic antitumor agents with superior cytotoxicity and overcoming multidrug resistance, a novel series of 4β-N-substituted podophyllotoxin derivatives were synthesized and evaluated as potential antitumor agents.Seven novel podophyllotoxin derivatives were synthesized by linking 4β-amino-4-deoxypodophyllotoxin with N-substituted 5-methylindol-3-yl-glyoxyl chlorides and tested against K562 and K562/A02 using SRB methods in vitro, KB and KBV using MTT methods in vitro.
2009, 20(12): 1435-1438
doi: 10.1016/j.cclet.2009.06.016
Abstract:
In this study, a novel series of chiral 1,2-propanediol derivatives with different terminal alkyl chain length were synthesized and characterized by FT-IR,1H NMR and DSC.After doped into a nematic liquid crystal host, all the chiral dopants induced chiral nematic liquid crystals exhibiting a helix inversion with temperature variation.The results indicate that terminal alkyl chain length has a prominent influence on helical twisting property of the chiral dopants.With increasing the terminal alkyl chain length, the molecular twisting power increases, the helix inversion temperatures varies slightly while the phase transition temperature decreases.An odd-even effect may exist in the molecular twisting power of the chiral dopants.
In this study, a novel series of chiral 1,2-propanediol derivatives with different terminal alkyl chain length were synthesized and characterized by FT-IR,1H NMR and DSC.After doped into a nematic liquid crystal host, all the chiral dopants induced chiral nematic liquid crystals exhibiting a helix inversion with temperature variation.The results indicate that terminal alkyl chain length has a prominent influence on helical twisting property of the chiral dopants.With increasing the terminal alkyl chain length, the molecular twisting power increases, the helix inversion temperatures varies slightly while the phase transition temperature decreases.An odd-even effect may exist in the molecular twisting power of the chiral dopants.
2009, 20(12): 1439-1443
doi: 10.1016/j.cclet.2009.06.017
Abstract:
A simple and efficient method for the iodination of aromatic compounds has been achieved in the presence of iodine and 1,4-bis(triphenylphosphonium)-2-butene peroxodisulfate.
A simple and efficient method for the iodination of aromatic compounds has been achieved in the presence of iodine and 1,4-bis(triphenylphosphonium)-2-butene peroxodisulfate.
2009, 20(12): 1444-1448
doi: 10.1016/j.cclet.2009.06.039
Abstract:
Silica-bonded S-sulfonic acid (SBSSA) was prepared by the reaction of 3-mercaptopropylsilica (MPS) and chlorosulfonic acidin chloroform.This solid acid has been employed as a recyclable catalyst for the synthesis of coumarins from phenols and β-ketoesters at 80 ℃ under solvent-free conditions.
Silica-bonded S-sulfonic acid (SBSSA) was prepared by the reaction of 3-mercaptopropylsilica (MPS) and chlorosulfonic acidin chloroform.This solid acid has been employed as a recyclable catalyst for the synthesis of coumarins from phenols and β-ketoesters at 80 ℃ under solvent-free conditions.
2009, 20(12): 1449-1452
doi: 10.1016/j.cclet.2009.06.023
Abstract:
A homologous series of benzothiazole derivatives, 6-methoxy-2-(4-alkanoyloxybenzylidenamino)benzothiazoles, were synthesized and characterized using FT-IR, 1H and 13C NMR, mass spectrometry and elemental analysis.Enantiotropic nematic phase was observed throughout the entire series.Smectic C phase only emerged from the decanoyloxy derivative onwards.The terminal methoxyl group and the ester linkage influenced the mesomorphic behavior of the present series.
A homologous series of benzothiazole derivatives, 6-methoxy-2-(4-alkanoyloxybenzylidenamino)benzothiazoles, were synthesized and characterized using FT-IR, 1H and 13C NMR, mass spectrometry and elemental analysis.Enantiotropic nematic phase was observed throughout the entire series.Smectic C phase only emerged from the decanoyloxy derivative onwards.The terminal methoxyl group and the ester linkage influenced the mesomorphic behavior of the present series.
2009, 20(12): 1453-1456
doi: 10.1016/j.cclet.2009.07.009
Abstract:
Boric acid (BO3H3) is an inexpensive, efficient and mild catalyst for the synthesis of 1,1-diacetate (acylal) from the various aromatic and heteroaryl aldehydes with acetic anhydride at room temperature under solvent-free condition.The present method does not involve any hazardous organic solvents or catalysts.This method gives notable advantages such as excellent chemoselectivity,mild reaction condition, short reaction times and excellent yield.
Boric acid (BO3H3) is an inexpensive, efficient and mild catalyst for the synthesis of 1,1-diacetate (acylal) from the various aromatic and heteroaryl aldehydes with acetic anhydride at room temperature under solvent-free condition.The present method does not involve any hazardous organic solvents or catalysts.This method gives notable advantages such as excellent chemoselectivity,mild reaction condition, short reaction times and excellent yield.
2009, 20(12): 1457-1460
doi: 10.1016/j.cclet.2009.07.006
Abstract:
Oxathioacetalyzation of carbonyl compounds with 2-mercaptoethanol and deprotection of the obtained 1,3-oxathiolanes is easily performed in the presence of silica sulfuric acid (SSA).All reactions were performed under mild and completely heterogeneous reaction conditions in good to high yields.
Oxathioacetalyzation of carbonyl compounds with 2-mercaptoethanol and deprotection of the obtained 1,3-oxathiolanes is easily performed in the presence of silica sulfuric acid (SSA).All reactions were performed under mild and completely heterogeneous reaction conditions in good to high yields.
2009, 20(12): 1461-1464
doi: 10.1016/j.cclet.2009.07.008
Abstract:
Two series of tanshinone ⅡA derivatives were synthesized and evaluated for their antitumor activities as Cdc25 phosphatase inhibitors.Most of them demonstrated potent Cdc25 inhibitory activity and powerful cytotoxicity against A549 tumor cell line,producing IC50 values in very low micromolar range.At last, the preliminary SAR was discussed.
Two series of tanshinone ⅡA derivatives were synthesized and evaluated for their antitumor activities as Cdc25 phosphatase inhibitors.Most of them demonstrated potent Cdc25 inhibitory activity and powerful cytotoxicity against A549 tumor cell line,producing IC50 values in very low micromolar range.At last, the preliminary SAR was discussed.
2009, 20(12): 1465-1468
doi: 10.1016/j.cclet.2009.05.025
Abstract:
In continuation of our chemical investigation on some medicinal plants of the genus Tephrosia, re-investigation of the methylenechloride/methanol (1:1) extract of the air-dried aerial part of Tephrosia apollinea afforded a new prenylated flavonoid 1,in addition to an aromatic ester, a sesquiterpene, a lignan and several known prenylated flavonoids.The structures were established by (1H NMR,13C NMR, DEPT,1H-1H COSY, HMQC, HMBC, NOESY and HRMS).Relative configurations of 9 and 10 wereconfirmed by X-ray analysis.
In continuation of our chemical investigation on some medicinal plants of the genus Tephrosia, re-investigation of the methylenechloride/methanol (1:1) extract of the air-dried aerial part of Tephrosia apollinea afforded a new prenylated flavonoid 1,in addition to an aromatic ester, a sesquiterpene, a lignan and several known prenylated flavonoids.The structures were established by (1H NMR,13C NMR, DEPT,1H-1H COSY, HMQC, HMBC, NOESY and HRMS).Relative configurations of 9 and 10 wereconfirmed by X-ray analysis.
2009, 20(12): 1469-1471
doi: 10.1016/j.cclet.2009.06.035
Abstract:
Two new prenylflavonoids, mornigrol E(1) and mornigrol F(2) were isolated from Morus nigra L.Their structures were elucidated on the basis of spectroscopic methods, especially 2D-NMR techniques.
Two new prenylflavonoids, mornigrol E(1) and mornigrol F(2) were isolated from Morus nigra L.Their structures were elucidated on the basis of spectroscopic methods, especially 2D-NMR techniques.
2009, 20(12): 1472-1474
doi: 10.1016/j.cclet.2009.07.014
Abstract:
A new sesquiterpene, named vladimenal (1), was isolated from the roots of Vladimiria souliei.The structure was elucidated on the basis of spectroscopic analysis.
A new sesquiterpene, named vladimenal (1), was isolated from the roots of Vladimiria souliei.The structure was elucidated on the basis of spectroscopic analysis.
2009, 20(12): 1475-1477
doi: 10.1016/j.cclet.2009.06.029
Abstract:
Aptamer-silver nanoparticles (AgNPs) based surface-enhanced Raman scattering (SERS) sensor has been developed for Hg2+detection by employing the structure-switching aptamer in the presence of spermine.This simple method shows excellent sensitivity and selectivity owing to the sensitive SERS detection technique and high specificity of aptamer for binding Hg2+.
Aptamer-silver nanoparticles (AgNPs) based surface-enhanced Raman scattering (SERS) sensor has been developed for Hg2+detection by employing the structure-switching aptamer in the presence of spermine.This simple method shows excellent sensitivity and selectivity owing to the sensitive SERS detection technique and high specificity of aptamer for binding Hg2+.
2009, 20(12): 1478-1482
doi: 10.1016/j.cclet.2009.07.013
Abstract:
In this paper, humic acid (HA) was ultra-filtered into different molecular weight sections and was characterized by multielementanalysis, UV254/TOC, FT-IR and three-dimensional fluorescence spectrometric.Since humic acids of different molecular weights have different hydrophilic and molecular size, the maximum adsorption capacity of basic ion exchange resins appears on the humic acid whose molecular weight ranges from 6000 to 10,000 Da.
In this paper, humic acid (HA) was ultra-filtered into different molecular weight sections and was characterized by multielementanalysis, UV254/TOC, FT-IR and three-dimensional fluorescence spectrometric.Since humic acids of different molecular weights have different hydrophilic and molecular size, the maximum adsorption capacity of basic ion exchange resins appears on the humic acid whose molecular weight ranges from 6000 to 10,000 Da.
2009, 20(12): 1483-1486
doi: 10.1016/j.cclet.2009.05.030
Abstract:
A new method for the simultaneous determination of fluorine and iodine in urine by ion chromatography (IC) with electrochemical pretreatment has been developed.The pretreatment was performed in a novel electrochemical oxidation-neutralization device (EOND), in which iodide of the sample was oxidized to iodate and the alkaline digestion sample solution was neutralized.Under the optimized conditions, the limits of detection (LOD, S/N=3) were 2.5 μg/L for fluoride and 20 μg/L for iodate, respectively.The recoveries were in the range of 93-102% for fluoride and 86-98% for iodate.
A new method for the simultaneous determination of fluorine and iodine in urine by ion chromatography (IC) with electrochemical pretreatment has been developed.The pretreatment was performed in a novel electrochemical oxidation-neutralization device (EOND), in which iodide of the sample was oxidized to iodate and the alkaline digestion sample solution was neutralized.Under the optimized conditions, the limits of detection (LOD, S/N=3) were 2.5 μg/L for fluoride and 20 μg/L for iodate, respectively.The recoveries were in the range of 93-102% for fluoride and 86-98% for iodate.
2009, 20(12): 1487-1490
doi: 10.1016/j.cclet.2009.07.005
Abstract:
The refolding of the reduced/denatured insulin from bovine pancreas as the model protein was investigated with weak anionexchange chromatography (WAX) coupled with MALDI-TOF MS.The results indicated that the disulfide bonds almost cannot be formed correctly with the common mobile phase by WAX.However, with the urea gradient elution and in the presence of GSSG/ Cyst as the ratio 1:6 in the mobile phase employed, the disulfide exchange of reduced/denatured insulin can be accelerated resulting in forming the correct three disulfide bonds.The protein refolding efficiency of reduced/denatured insulin can be increased from 3% to 34%.The effects of urea gradient and the oxidant and reductant groups, such as GSSG/GSH, Cyst, and GSSG/Cyst, on the forming the disulfide bonds of reduced/denatured insulin were investigated in detail.The results were further tested by the separation of the WAX fraction of reduced/denatured insulin with RPLC and MALDI-TOF MS.
The refolding of the reduced/denatured insulin from bovine pancreas as the model protein was investigated with weak anionexchange chromatography (WAX) coupled with MALDI-TOF MS.The results indicated that the disulfide bonds almost cannot be formed correctly with the common mobile phase by WAX.However, with the urea gradient elution and in the presence of GSSG/ Cyst as the ratio 1:6 in the mobile phase employed, the disulfide exchange of reduced/denatured insulin can be accelerated resulting in forming the correct three disulfide bonds.The protein refolding efficiency of reduced/denatured insulin can be increased from 3% to 34%.The effects of urea gradient and the oxidant and reductant groups, such as GSSG/GSH, Cyst, and GSSG/Cyst, on the forming the disulfide bonds of reduced/denatured insulin were investigated in detail.The results were further tested by the separation of the WAX fraction of reduced/denatured insulin with RPLC and MALDI-TOF MS.
2009, 20(12): 1491-1494
doi: 10.1016/j.cclet.2009.06.030
Abstract:
A rapid and simple preconcentration step applying packed-fiber solid-phase extraction columns has been investigated to vitamin B 12.The extraction performance of the new method was investigated preliminarily on vitamin functional drink.The analysis used a reversed-phase C18 column, with a photo-diode array detector at 220 nm.The samples were preconcentrated with packed-fiber solid-phase extraction columns.Good linearity was observed in vitamin functional drink.The repeatability of extraction performance, expressed as relative standard deviations, was from 3.5% to 4.3%.The limit of detection (LOD) is 5 ng mL-1(S/N=3).Finally, the method had been applied for the determination of vitamin B 12 in vitamin functional drink.
A rapid and simple preconcentration step applying packed-fiber solid-phase extraction columns has been investigated to vitamin B 12.The extraction performance of the new method was investigated preliminarily on vitamin functional drink.The analysis used a reversed-phase C18 column, with a photo-diode array detector at 220 nm.The samples were preconcentrated with packed-fiber solid-phase extraction columns.Good linearity was observed in vitamin functional drink.The repeatability of extraction performance, expressed as relative standard deviations, was from 3.5% to 4.3%.The limit of detection (LOD) is 5 ng mL-1(S/N=3).Finally, the method had been applied for the determination of vitamin B 12 in vitamin functional drink.
2009, 20(12): 1495-1497
doi: 10.1016/j.cclet.2009.06.031
Abstract:
New matrix, metal-phthalocyanine (MPc), of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used for analysis of small molecules (usually < 500 Da).By using MPcs as matrices, small molecular samples were moved to high mass-to-charge region where there was no interference caused by the traditional matrices.The mass of the target analyte was obtained by simple calculation.
New matrix, metal-phthalocyanine (MPc), of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used for analysis of small molecules (usually < 500 Da).By using MPcs as matrices, small molecular samples were moved to high mass-to-charge region where there was no interference caused by the traditional matrices.The mass of the target analyte was obtained by simple calculation.
2009, 20(12): 1498-1501
doi: 10.1016/j.cclet.2009.07.016
Abstract:
In this work, a novel hollow fiber membrane extractor was set up to extract inorganic anions from ethyl acetate using deionized water.Inorganic anions in slightly soluble organic solvents can be determined by the in-line hollow fiber membrane extractor coupled with ion chromatography at first time.Different aspects of the extraction procedure such as magnetic stirring speed,extraction flow rate and extraction time were optimized to achieve high extraction efficiency and good separation results.Satisfactory linear range, limits of detection and good repeatability were obtained.The procedure was applied to analyze inorganic anions in two commercial ethyl acetate samples.
In this work, a novel hollow fiber membrane extractor was set up to extract inorganic anions from ethyl acetate using deionized water.Inorganic anions in slightly soluble organic solvents can be determined by the in-line hollow fiber membrane extractor coupled with ion chromatography at first time.Different aspects of the extraction procedure such as magnetic stirring speed,extraction flow rate and extraction time were optimized to achieve high extraction efficiency and good separation results.Satisfactory linear range, limits of detection and good repeatability were obtained.The procedure was applied to analyze inorganic anions in two commercial ethyl acetate samples.
2009, 20(12): 1502-1505
doi: 10.1016/j.cclet.2009.06.013
Abstract:
A novel poly(ethylene glycol) (PEG) analogue composed of aliphatic polyester backbone and pendant oligo(ethylene glycol) short chains is reported.The PEG analogue is a copolymer synthesized by ring-opening alternating copolymerization of succinicanhydride with 2-((2-(2-metho xyethoxy)ethoxy)methyl)oxirane.The structure of the copolymer was confirmed by 1H NMRspectrum.The effects of the monomer feed ratio on the copolymerization were studied and the polymerization mechanism was given.The PEG analogue disclosed is water-soluble and expected to have promising applications in biomedical fields as a substitute of PEG due to the existence of degradable ester bond in the backbone.
A novel poly(ethylene glycol) (PEG) analogue composed of aliphatic polyester backbone and pendant oligo(ethylene glycol) short chains is reported.The PEG analogue is a copolymer synthesized by ring-opening alternating copolymerization of succinicanhydride with 2-((2-(2-metho xyethoxy)ethoxy)methyl)oxirane.The structure of the copolymer was confirmed by 1H NMRspectrum.The effects of the monomer feed ratio on the copolymerization were studied and the polymerization mechanism was given.The PEG analogue disclosed is water-soluble and expected to have promising applications in biomedical fields as a substitute of PEG due to the existence of degradable ester bond in the backbone.
2009, 20(12): 1506-1509
doi: 10.1016/j.cclet.2009.07.012
Abstract:
Poly(d,l-lactide-co-p-dioxanone) (P(LA-co-PDO)) copolymers with different chain microstructures were synthesized by onestep or two-step bulk ring-opening polymerizations of d,l-lactide (LA) and p-dioxanone (PDO) monomers using stannous octoate [Sn(Oct)2 ]/n-dodecanol as the initiating system.The average sequence lengths of the lactidyl (LLA) and dioxanyl (LPDO) units were calculated from the 1H NMR spectra.It was found that both LLA and LPDO values from the two-step syntheses were significantly longer than those from the corresponding one-step syntheses, indicating more blocky structure achieved for the twostep copolymers.Corresponding to this difference in microstructure, the two-step copolymers were semi-crystalline, while the one-step copolymers were completely amorphous.In conclusion, the crystallinity of P(LA-co-PDO) copolymers could be adjusted conveniently to meet specific applications by changing the microstructure of the copolymers via different polymerization routes.
Poly(d,l-lactide-co-p-dioxanone) (P(LA-co-PDO)) copolymers with different chain microstructures were synthesized by onestep or two-step bulk ring-opening polymerizations of d,l-lactide (LA) and p-dioxanone (PDO) monomers using stannous octoate [Sn(Oct)2 ]/n-dodecanol as the initiating system.The average sequence lengths of the lactidyl (LLA) and dioxanyl (LPDO) units were calculated from the 1H NMR spectra.It was found that both LLA and LPDO values from the two-step syntheses were significantly longer than those from the corresponding one-step syntheses, indicating more blocky structure achieved for the twostep copolymers.Corresponding to this difference in microstructure, the two-step copolymers were semi-crystalline, while the one-step copolymers were completely amorphous.In conclusion, the crystallinity of P(LA-co-PDO) copolymers could be adjusted conveniently to meet specific applications by changing the microstructure of the copolymers via different polymerization routes.
2009, 20(12): 1510-1513
doi: 10.1016/j.cclet.2009.07.004
Abstract:
Four novel copoly(ester-imide)s based on 3,3',4,4'-biphenyltetracarboxylic dianhydride, bis(trimellitic acid anhydride) phenyl ester and di-p-aminophenyl ester of dicarboxylic acids were synthesized via two-step method in order to investigate whether two imide mesogenic units with different conformation and polarity could control the formation of LC-phase.Polarizes light microscopy (PLM) and differential scanning calorimetry (DSC) have shown that three polymers formed the nematic phase with "thread schlieren texture" and a polymer formed the nematic phase with "Inversion walls texture".
Four novel copoly(ester-imide)s based on 3,3',4,4'-biphenyltetracarboxylic dianhydride, bis(trimellitic acid anhydride) phenyl ester and di-p-aminophenyl ester of dicarboxylic acids were synthesized via two-step method in order to investigate whether two imide mesogenic units with different conformation and polarity could control the formation of LC-phase.Polarizes light microscopy (PLM) and differential scanning calorimetry (DSC) have shown that three polymers formed the nematic phase with "thread schlieren texture" and a polymer formed the nematic phase with "Inversion walls texture".
2009, 20(12): 1514-1517
doi: 10.1016/j.cclet.2009.06.027
Abstract:
A series of polydimethylsiloxanes containing two primary hydroxyl groups at one single chain end were synthesized by five-step reactions which included esterification, hydroxyl protection, anionic ring-opening polymerization, hydrosilylation and deprotection.The prepared compounds in each step were characterized.The results showed that each step synthesis was successfully carried out and objective products could be achieved.
A series of polydimethylsiloxanes containing two primary hydroxyl groups at one single chain end were synthesized by five-step reactions which included esterification, hydroxyl protection, anionic ring-opening polymerization, hydrosilylation and deprotection.The prepared compounds in each step were characterized.The results showed that each step synthesis was successfully carried out and objective products could be achieved.
