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2007 Volume 24 Issue 8
2007, 24(8): 853-857
Abstract:
A series of novel 1,8-naphthalimide fluorescent dyes have been designed and synthesized by introducing different aromatic units at 4-position through Suzuki and Stille coupling reactions,and their photophysical properties,e.g.UV-Vis absorption,photoluminescence and electrochemical behavior,were studied.All these compounds emit blue light,exhibiting photoluminescence (PL) with absorption and PL maxima in the range of 357~378 and 423~451 nm respectively in toluene.As increasing electron-donating capability of aromatic substituent,both absorption and photoluminescence are red shifted.The structures of the aromatic units significantly affect the PL properties of the compounds.The compound with methoxyphenyl substituent exhibits the highest PL quantum yield up to 0.98,while that bearing thienyl unit shows the lowest PL quantum yield of 0.17.Cyclic voltammogram measurements indicate that these compounds have high electron affinity attributed to the 1,8-naphthalimide unit.The aromatic units only affect the highest occupied molecular orbital (HOMO) energy levels,but not the lowest unoccupied molecular orbital (LUMO) energy levels,meaning that the LUMO energy levels are determined by 1,8-naphthalimide unit.
A series of novel 1,8-naphthalimide fluorescent dyes have been designed and synthesized by introducing different aromatic units at 4-position through Suzuki and Stille coupling reactions,and their photophysical properties,e.g.UV-Vis absorption,photoluminescence and electrochemical behavior,were studied.All these compounds emit blue light,exhibiting photoluminescence (PL) with absorption and PL maxima in the range of 357~378 and 423~451 nm respectively in toluene.As increasing electron-donating capability of aromatic substituent,both absorption and photoluminescence are red shifted.The structures of the aromatic units significantly affect the PL properties of the compounds.The compound with methoxyphenyl substituent exhibits the highest PL quantum yield up to 0.98,while that bearing thienyl unit shows the lowest PL quantum yield of 0.17.Cyclic voltammogram measurements indicate that these compounds have high electron affinity attributed to the 1,8-naphthalimide unit.The aromatic units only affect the highest occupied molecular orbital (HOMO) energy levels,but not the lowest unoccupied molecular orbital (LUMO) energy levels,meaning that the LUMO energy levels are determined by 1,8-naphthalimide unit.
2007, 24(8): 858-862
Abstract:
Bonding reaction of Furbenicillin Sodium (FBS) with bovine serum albumin (BSA) was studied by means of UV-Vis,fluorescence and infrared spectroscopy.The experimental results suggest that there is strong interaction between FBS and BSA,and FBS has a strong quenching effect on the BSA fluorescence.It is confirmed from fluorescence data that the quenching effect of FBS on the BSA fluorescence is a single static quenching process.The fluorescence quenching data was analyzed using the Stern-Volmer equation and double-logarithm equation.The binding constant and binding sites were 1.04×105 and 1.09 at ambient temperature (26℃),respectively.It is revealed from the above results that the bonding of FBS with BSA leads to a significant change of the secondary structure of BSA.
Bonding reaction of Furbenicillin Sodium (FBS) with bovine serum albumin (BSA) was studied by means of UV-Vis,fluorescence and infrared spectroscopy.The experimental results suggest that there is strong interaction between FBS and BSA,and FBS has a strong quenching effect on the BSA fluorescence.It is confirmed from fluorescence data that the quenching effect of FBS on the BSA fluorescence is a single static quenching process.The fluorescence quenching data was analyzed using the Stern-Volmer equation and double-logarithm equation.The binding constant and binding sites were 1.04×105 and 1.09 at ambient temperature (26℃),respectively.It is revealed from the above results that the bonding of FBS with BSA leads to a significant change of the secondary structure of BSA.
2007, 24(8): 863-867
Abstract:
The synthesis of a novel rotaxane containing α-CD (α-cyclodextrin) as the macrocycle,stilbene as the ‘string’ and the isophthalic acid as stopper via a palladium-catalyzed Suzuki coupling reaction in water at room temperature and supramolecular self-assembly was reported.Concentrated HCl was added to the reaction solution to change the pH value of the reaction solution after the reaction finished.The rotaxane could be separated from the reaction solution which contained excessive α-CD by extraction with n-butanol and then the rotaxane containing one α-CD macrocycle was purified by silica gel.The solubility of rotaxane could be tuned up by changing the structure of the ‘string’ in order to get the rotaxane which was soluble in organic solvent.The molar ratio of α-CD to the ‘string’ was 1:1 and the rotaxane was [2] rotaxane according to the results of 1H NMR spectroscopy and mass spectrometry of rotaxane.
The synthesis of a novel rotaxane containing α-CD (α-cyclodextrin) as the macrocycle,stilbene as the ‘string’ and the isophthalic acid as stopper via a palladium-catalyzed Suzuki coupling reaction in water at room temperature and supramolecular self-assembly was reported.Concentrated HCl was added to the reaction solution to change the pH value of the reaction solution after the reaction finished.The rotaxane could be separated from the reaction solution which contained excessive α-CD by extraction with n-butanol and then the rotaxane containing one α-CD macrocycle was purified by silica gel.The solubility of rotaxane could be tuned up by changing the structure of the ‘string’ in order to get the rotaxane which was soluble in organic solvent.The molar ratio of α-CD to the ‘string’ was 1:1 and the rotaxane was [2] rotaxane according to the results of 1H NMR spectroscopy and mass spectrometry of rotaxane.
2007, 24(8): 868-872
Abstract:
A novel glassy carbon electrode modified with spherical platinum nanoparticles was prepared by means of a one-step in situ chemical reduction growth method.Electrochemical method SEM and EDS for surface analysis were employed to characterize the platinum nanparticles modification on the electrode surface.The comparison of the electrochemical properties of bare glassy carbon electrode,platinum nanoparticles-modified electrode and bulk platinum electrode is performed.The surface coverage rate (1.28×10-7 mol/cm2) of platinum on glassy carbon electrode was calculated based on the linear relationship between peak current of Pt and scan rate.The results show that the modified electrode exhibited an effective response to the oxidation of L-Cysteine.Compared with that of Pt bulk electrode,the electrocatalytic oxidation potential of L-Cysteine on modified electrode has shifted negatively by 0.3 V with a remarkable enhancement in oxidation peak current.The linear relationship existed between the L-Cysteine concentration and the catalytic peak current in a range of 1.0×10-7 mol/L to 1.0×10-5 mol/L at the modified electrode.
A novel glassy carbon electrode modified with spherical platinum nanoparticles was prepared by means of a one-step in situ chemical reduction growth method.Electrochemical method SEM and EDS for surface analysis were employed to characterize the platinum nanparticles modification on the electrode surface.The comparison of the electrochemical properties of bare glassy carbon electrode,platinum nanoparticles-modified electrode and bulk platinum electrode is performed.The surface coverage rate (1.28×10-7 mol/cm2) of platinum on glassy carbon electrode was calculated based on the linear relationship between peak current of Pt and scan rate.The results show that the modified electrode exhibited an effective response to the oxidation of L-Cysteine.Compared with that of Pt bulk electrode,the electrocatalytic oxidation potential of L-Cysteine on modified electrode has shifted negatively by 0.3 V with a remarkable enhancement in oxidation peak current.The linear relationship existed between the L-Cysteine concentration and the catalytic peak current in a range of 1.0×10-7 mol/L to 1.0×10-5 mol/L at the modified electrode.
2007, 24(8): 873-877
Abstract:
β-Ni(OH)2 precursor was prepared by direct depositing and then sample powder was obtained by calcining the prepared β-Ni(OH)2.The results of XRD,SEM and BET for the product show that the samples were cubic NiO.Its supercapacitor properties were studied by cyclic voltammetry (CV),constant current charge/discharge and electrochemical impedance spectroscopy (EIS).The results indicate that NiO exhibits typical Faraday capacitance characteristics.When pH is 11~12,deposition temperature is 30℃ and calcining temperature is 300℃,the specific capacitance of NiO could reach 346 F/g at 3×10-3 A/cm2.The resistance of electrode electrochemistry reaction is 0.24 Ω,the resistance related to the conductivity of the electrode and electrolyte is 0.085 Ω.The obtained NiO has a long cycle life.After 100 times cycles by 5×10-3 A/cm2,the specific capacitance remains 291.5 F/g and the coulombic efficiency is 93.5%.
β-Ni(OH)2 precursor was prepared by direct depositing and then sample powder was obtained by calcining the prepared β-Ni(OH)2.The results of XRD,SEM and BET for the product show that the samples were cubic NiO.Its supercapacitor properties were studied by cyclic voltammetry (CV),constant current charge/discharge and electrochemical impedance spectroscopy (EIS).The results indicate that NiO exhibits typical Faraday capacitance characteristics.When pH is 11~12,deposition temperature is 30℃ and calcining temperature is 300℃,the specific capacitance of NiO could reach 346 F/g at 3×10-3 A/cm2.The resistance of electrode electrochemistry reaction is 0.24 Ω,the resistance related to the conductivity of the electrode and electrolyte is 0.085 Ω.The obtained NiO has a long cycle life.After 100 times cycles by 5×10-3 A/cm2,the specific capacitance remains 291.5 F/g and the coulombic efficiency is 93.5%.
2007, 24(8): 878-882
Abstract:
A Schiff-base ligated aluminum complex was synthesized by the treatment of aluminum tris (isopropoxide) swith a neutral Schiff-base compound.NMR and X-ray analyses reveal that the compound is a dimmer.Aluminum ion is coordinated with nitrogen and oxygen atoms from the ligand to form a unit.The two units are bridged by methoxy groups to generate a bimetallic structure.The aluminum ion and methoxy oxygen form a rhombus core that contains the symmetry center of the molecule.The complex shows efficient activity towards the ring-opening polymerization of ε-caprolactone to give a biodegradable polylactone.Dynamic analysis shows that both the conversion of monomer and molecular mass of the resultant polymer increase linearly with reaction time,and the molecular mass fits well with the theoretical value,while the molecular mass distribution keeps unchanged,indicating a living polymerization fashion.The end groups of the oligo-meric product were characterized by NMR spectroscopic analysis.One is methoxy derived from initiator Al-OCH3 while the other is hydroxyl from terminator methanol,suggesting a coordination insertion mechanism.
A Schiff-base ligated aluminum complex was synthesized by the treatment of aluminum tris (isopropoxide) swith a neutral Schiff-base compound.NMR and X-ray analyses reveal that the compound is a dimmer.Aluminum ion is coordinated with nitrogen and oxygen atoms from the ligand to form a unit.The two units are bridged by methoxy groups to generate a bimetallic structure.The aluminum ion and methoxy oxygen form a rhombus core that contains the symmetry center of the molecule.The complex shows efficient activity towards the ring-opening polymerization of ε-caprolactone to give a biodegradable polylactone.Dynamic analysis shows that both the conversion of monomer and molecular mass of the resultant polymer increase linearly with reaction time,and the molecular mass fits well with the theoretical value,while the molecular mass distribution keeps unchanged,indicating a living polymerization fashion.The end groups of the oligo-meric product were characterized by NMR spectroscopic analysis.One is methoxy derived from initiator Al-OCH3 while the other is hydroxyl from terminator methanol,suggesting a coordination insertion mechanism.
2007, 24(8): 883-887
Abstract:
Magnetic Ni-Al hydrotalcites were synthesized with different amounts of magnetic substrate and Ni-Al hydrotalcite-like compounds.The influences of the amount of magnetic substrate,calcination temperature on the structure were studied.The obtained samples were characterized by SEM,XRD,FT-IR,DSC-TG,and VSM.The results indicate that the introduction of magnetic substrate endows Ni-Al hydrotalcite a super-magnetism feature.The magnetism depends on the amount of the magnetic substrate.The saturation magnetization of magnetic Ni-Al hydrotalcite is enhanced with the increasing of magnetic substrate.X-ray diffraction patterns show the layered structures of magnetic Ni-Al hydrotalcites are not affected by introducing a certain amount of magnetic substrate and the diffraction peaks decrease with increasing the amount of magnetic substrate.When the n(Ni2+)/n(Fe2+) molar ratio reaches 20,XRD diffraction peaks of the Fe3O4 phase begin to emerge.When the temperature is increased to 1 073 K,the spinel phase is observed.The DSC-TG curves show two endothermal peaks are not affected by introducing magnetic substrate,and is consistent with XRD result.
Magnetic Ni-Al hydrotalcites were synthesized with different amounts of magnetic substrate and Ni-Al hydrotalcite-like compounds.The influences of the amount of magnetic substrate,calcination temperature on the structure were studied.The obtained samples were characterized by SEM,XRD,FT-IR,DSC-TG,and VSM.The results indicate that the introduction of magnetic substrate endows Ni-Al hydrotalcite a super-magnetism feature.The magnetism depends on the amount of the magnetic substrate.The saturation magnetization of magnetic Ni-Al hydrotalcite is enhanced with the increasing of magnetic substrate.X-ray diffraction patterns show the layered structures of magnetic Ni-Al hydrotalcites are not affected by introducing a certain amount of magnetic substrate and the diffraction peaks decrease with increasing the amount of magnetic substrate.When the n(Ni2+)/n(Fe2+) molar ratio reaches 20,XRD diffraction peaks of the Fe3O4 phase begin to emerge.When the temperature is increased to 1 073 K,the spinel phase is observed.The DSC-TG curves show two endothermal peaks are not affected by introducing magnetic substrate,and is consistent with XRD result.
2007, 24(8): 888-892
Abstract:
A cyanation process of aryl halides with K4[Fe(CN)6]3H2O as the cyanation reagent in the presence of Pd(OAc)2 and Na2CO3 was studied.Factors affecting the reaction such as the ratio of reactants,time,temperature,amount of catalyst on the cyanation was investigated.Optimal reaction conditions were determined to be:130℃,n(K4[Fe(CN)6]·3H2O):n(ArBr):n(Pd(OAc)2)=200:1 000:1,and 1.5 h.The conversion of the bromobenzene could reach 99% and cyanobenzene could be obtained with a yield of 95%.Compared with the traditional cyanating agents,potassium hexacyanoferrate (Ⅱ) is non-toxic,affordble and readily available without the need of complicated pre-processing.The protocol is proceeded in the presence of small amounts of palladium catalyst and is easy to operate.It is not necessary to add any expensive ligand,and is less environment polluting and apparently is economically beneficial.Cyanation of other aryl halides was also performed.Both active aryl bromides and aryl iodides gave the corresponding benzonitriles with 91%~96% yields.
A cyanation process of aryl halides with K4[Fe(CN)6]3H2O as the cyanation reagent in the presence of Pd(OAc)2 and Na2CO3 was studied.Factors affecting the reaction such as the ratio of reactants,time,temperature,amount of catalyst on the cyanation was investigated.Optimal reaction conditions were determined to be:130℃,n(K4[Fe(CN)6]·3H2O):n(ArBr):n(Pd(OAc)2)=200:1 000:1,and 1.5 h.The conversion of the bromobenzene could reach 99% and cyanobenzene could be obtained with a yield of 95%.Compared with the traditional cyanating agents,potassium hexacyanoferrate (Ⅱ) is non-toxic,affordble and readily available without the need of complicated pre-processing.The protocol is proceeded in the presence of small amounts of palladium catalyst and is easy to operate.It is not necessary to add any expensive ligand,and is less environment polluting and apparently is economically beneficial.Cyanation of other aryl halides was also performed.Both active aryl bromides and aryl iodides gave the corresponding benzonitriles with 91%~96% yields.
2007, 24(8): 893-898
Abstract:
The binding abilities of chitosan of low molecular mass and its water-soluble derivatives (O-CMCS and O-HECS) with of plasmids DNA pBR322 and pUC18 were studied in vitro at different mass fractions and reactive time.The results show that raw chitosan had strong effect on both plasmids and the influencing degrees were stable.The effect of the chitosan derivatives on the plasmids depended on space effect and the quantity of the amido groups.At appropriate mass fractions (larger than 1×10-2) and relative molecular mass (2 000,5 000,8 000 and higher than 8 000),the chitosan derivatives may have strong abilities to combine with DNA.The influencing degrees of chitosan and its derivatives on the plasmids have nothing to do with time,because the combination is based on charge attraction and the process is transitory.The experiment focused on the relationship between chitosans (with molecular Mass of 3 000~5 000) and mRNA showed that raw chitosan and O-CMCS could hinder the duplication of mRNA,and O-CMCS had a greater influence.The results might be caused by stronger protonating ability and huge volume of O-CMCS.The experiment of E.coli transfection in vivo showed that chitosan and O-CMCS can not only bind DNA but also directly hinder the transfection from the DNA to E.coli.
The binding abilities of chitosan of low molecular mass and its water-soluble derivatives (O-CMCS and O-HECS) with of plasmids DNA pBR322 and pUC18 were studied in vitro at different mass fractions and reactive time.The results show that raw chitosan had strong effect on both plasmids and the influencing degrees were stable.The effect of the chitosan derivatives on the plasmids depended on space effect and the quantity of the amido groups.At appropriate mass fractions (larger than 1×10-2) and relative molecular mass (2 000,5 000,8 000 and higher than 8 000),the chitosan derivatives may have strong abilities to combine with DNA.The influencing degrees of chitosan and its derivatives on the plasmids have nothing to do with time,because the combination is based on charge attraction and the process is transitory.The experiment focused on the relationship between chitosans (with molecular Mass of 3 000~5 000) and mRNA showed that raw chitosan and O-CMCS could hinder the duplication of mRNA,and O-CMCS had a greater influence.The results might be caused by stronger protonating ability and huge volume of O-CMCS.The experiment of E.coli transfection in vivo showed that chitosan and O-CMCS can not only bind DNA but also directly hinder the transfection from the DNA to E.coli.
2007, 24(8): 899-904
Abstract:
Multi-walled carbon nanotubes (MWNTs) were pretreated ultrasonically in 36% HCl and then functionalized in 2.2 mol/L HNO3,and then dispersed in N,N-dimethylformamide (DMF).The MWNTs modified glassy carbon electrode (MWNTs/GCE) was prepared by dropping 2 μL of MWNTs (0.1 g/L) in DMF on the surface of a glassy carbon electrode.The MWNTs/GCE can catalyze the electro-oxidation of ascorbic acid (AA).On the cyclic voltammogram,AA has two well-separated oxiditive peaks in pH=4.0 B-R buffer solution at 0.187 V and 0.452 V (vs.SCE),respectively,the mechanism of which can be illustrated according to the molecular structure of AA and the electrocatalytic properties of the carboxylic acid group-functionalized MWNTs.The electro-oxidation of AA at MWNTs/GCE is an adsorption-controlled irreversible electrode process.The surface concentration of AA on the electrode was calculated to be 1.02×10-9 mol/cm2,and the standard rate constants of the electrode reactions of the two oxidative peaks of AA were calculated to be 1.03×10-2 s-1 and 3.94×10-3 s-1,respectively.AA was satisfactorily detected by using differential pulse voltammetry with a linear range from 5.0×10-7 mol/L to 5.0×10-2 mol/L and a detection limit of 5.0×10-8 mol/L (S/N=3).
Multi-walled carbon nanotubes (MWNTs) were pretreated ultrasonically in 36% HCl and then functionalized in 2.2 mol/L HNO3,and then dispersed in N,N-dimethylformamide (DMF).The MWNTs modified glassy carbon electrode (MWNTs/GCE) was prepared by dropping 2 μL of MWNTs (0.1 g/L) in DMF on the surface of a glassy carbon electrode.The MWNTs/GCE can catalyze the electro-oxidation of ascorbic acid (AA).On the cyclic voltammogram,AA has two well-separated oxiditive peaks in pH=4.0 B-R buffer solution at 0.187 V and 0.452 V (vs.SCE),respectively,the mechanism of which can be illustrated according to the molecular structure of AA and the electrocatalytic properties of the carboxylic acid group-functionalized MWNTs.The electro-oxidation of AA at MWNTs/GCE is an adsorption-controlled irreversible electrode process.The surface concentration of AA on the electrode was calculated to be 1.02×10-9 mol/cm2,and the standard rate constants of the electrode reactions of the two oxidative peaks of AA were calculated to be 1.03×10-2 s-1 and 3.94×10-3 s-1,respectively.AA was satisfactorily detected by using differential pulse voltammetry with a linear range from 5.0×10-7 mol/L to 5.0×10-2 mol/L and a detection limit of 5.0×10-8 mol/L (S/N=3).
2007, 24(8): 905-910
Abstract:
Two novel dinuclear Mn2+ ion coordination complexes Mn2(C7H4O2Cl)4(Phen)2(μ-H2O)(1) and[Mn2(btec)(bipy)2(H2O)6]·(H2O)2 (2),(phen=1,10-phenanthroline,bipy=2,2'-bipyridyl,H4btec=1,2,4,5-benzenetetracarboxylic acid) were synthesized by the normal and hydrothermal method.Their structures were determined by single crystal X-ray diffraction.Complex 1 crystallized in the monoclinic system with space group C2/c,a=2.339 3(5),b=1.558 5(3),c=1.559 6(3) nm,β=121.03(3)°,Z=4,R1=0.075 0,wR2=0.1602.Complex 2 crystallized in the monoclinic system with space group P2(1)/n,a=1.252 98(8),b=0.769 92(5),c=1.800 90(11) nm,β=100.163 0(10)°,Z=2,R1=0.029 6,wR2=0.082 7.In complex 1,two p-chloro-benzoic acid groups together with one water molecule act as the bridges to link the Mn2+ ion,forming a dinuclear structure.In complex 2,btec group act as the bridge to coordinate to two Mn2+ ions through two p-carboxylic O atoms in a mono-dentate mode,and complex 2 is therefore linked to a dinuclear structure.Complex 2 is further connected to a 2D structure by hydrogen bonds.The surface photovoltage spectra (SPS) of complexes 1 and 2 indicate that they all possess positive surface photovoltage (SPV) responses at 300~800 nm.They exhibit certain semiconductor behavior and take on p-type characteristic.In addition,the differences of their structures have certain effect on their SPV responses.
Two novel dinuclear Mn2+ ion coordination complexes Mn2(C7H4O2Cl)4(Phen)2(μ-H2O)(1) and[Mn2(btec)(bipy)2(H2O)6]·(H2O)2 (2),(phen=1,10-phenanthroline,bipy=2,2'-bipyridyl,H4btec=1,2,4,5-benzenetetracarboxylic acid) were synthesized by the normal and hydrothermal method.Their structures were determined by single crystal X-ray diffraction.Complex 1 crystallized in the monoclinic system with space group C2/c,a=2.339 3(5),b=1.558 5(3),c=1.559 6(3) nm,β=121.03(3)°,Z=4,R1=0.075 0,wR2=0.1602.Complex 2 crystallized in the monoclinic system with space group P2(1)/n,a=1.252 98(8),b=0.769 92(5),c=1.800 90(11) nm,β=100.163 0(10)°,Z=2,R1=0.029 6,wR2=0.082 7.In complex 1,two p-chloro-benzoic acid groups together with one water molecule act as the bridges to link the Mn2+ ion,forming a dinuclear structure.In complex 2,btec group act as the bridge to coordinate to two Mn2+ ions through two p-carboxylic O atoms in a mono-dentate mode,and complex 2 is therefore linked to a dinuclear structure.Complex 2 is further connected to a 2D structure by hydrogen bonds.The surface photovoltage spectra (SPS) of complexes 1 and 2 indicate that they all possess positive surface photovoltage (SPV) responses at 300~800 nm.They exhibit certain semiconductor behavior and take on p-type characteristic.In addition,the differences of their structures have certain effect on their SPV responses.
2007, 24(8): 911-916
Abstract:
Nine uniquely functionalized antifouling acrylamide monomers derived from capsaicin were designed and synthesized.The yield of the reaction and the mp were respectively analyzed,and their stuctures were characterized by 1H NMR and FTIR.Seven of them including BMA,TMBA,HMTBA,HMMBA,CHBA,BHBA,HDMBA were synthesized for the first time.Growth inhibition assay result in the laboratory shows that those synthesized monomers possess an antifouling activity against Nitzschia closterium in the order of HDMBA >DMBA≈BMA >TMBA≈HMTBA >CHBA >HMMBA >BHBA >HMBA.
Nine uniquely functionalized antifouling acrylamide monomers derived from capsaicin were designed and synthesized.The yield of the reaction and the mp were respectively analyzed,and their stuctures were characterized by 1H NMR and FTIR.Seven of them including BMA,TMBA,HMTBA,HMMBA,CHBA,BHBA,HDMBA were synthesized for the first time.Growth inhibition assay result in the laboratory shows that those synthesized monomers possess an antifouling activity against Nitzschia closterium in the order of HDMBA >DMBA≈BMA >TMBA≈HMTBA >CHBA >HMMBA >BHBA >HMBA.
2007, 24(8): 917-920
Abstract:
The reaction of p-methylphenyltrimethylsilyl ether (1) with 4,4'-dichlorodiphenylsulfone (2) in DMF and in the presence of tetrabutylammonium fluoride (TBAF) at 100℃ for 1 h afforded 4,4'-bis(4-methylphenoxy) diphenyl sulfone (3) in a yield of 92%.Then compopund 3 was oxidized in air to the corresponding intermediate 4,4'-bis(4-carboxyphenoxy) diphenyl sulfone (4) in a yield of 90% in the presence of a catalytic amount of N-bromosuccinimde (NBS) under photoirradiation.Subsequently the reaction of compound 4 with thionyl chloride yielded target compound 4,4'-bis(4-chloroformylphenoxy) diphenylsulfone (5) in a overall yield of about 74.5% (based on compound 1).The present method has the advantages of readily availability of starting materials,mild reaction conditions,convenient manipulation and good yields.
The reaction of p-methylphenyltrimethylsilyl ether (1) with 4,4'-dichlorodiphenylsulfone (2) in DMF and in the presence of tetrabutylammonium fluoride (TBAF) at 100℃ for 1 h afforded 4,4'-bis(4-methylphenoxy) diphenyl sulfone (3) in a yield of 92%.Then compopund 3 was oxidized in air to the corresponding intermediate 4,4'-bis(4-carboxyphenoxy) diphenyl sulfone (4) in a yield of 90% in the presence of a catalytic amount of N-bromosuccinimde (NBS) under photoirradiation.Subsequently the reaction of compound 4 with thionyl chloride yielded target compound 4,4'-bis(4-chloroformylphenoxy) diphenylsulfone (5) in a overall yield of about 74.5% (based on compound 1).The present method has the advantages of readily availability of starting materials,mild reaction conditions,convenient manipulation and good yields.
2007, 24(8): 921-924
Abstract:
Multi-wall carbon nanotubes modified glassy carbon electrode (MWNT/GCE) was prepared,and the electrocatalysis of vitamin B12(VB12) and analytic conditions of VB12 on the electrode were studied.The results indicate that two pairs of redox peaks of VB12 at MWCNT/GCE are obtained by cyclic voltammetry in the mixture of 0.1 mol/L KCl as supporting electrolyte and phosphatic buffer solution (pH=7.0).The formal potentials are -0.10 V and -0.85 V (vs.SCE),respectively.The 1st order derivative of the current of reduction peak at -0.85 V is linearly related to the concentration of VB12 in the range of 1×10-8~4×10-7 mol/L,which obeys the equation i'p=5.958×10-7+2.885c(R=0.995) and the detection limit can reach to 1.5×10-9 mol/L.This electrode has been applied to directly determining VB12 in tablets with a recovery of 97.3%~107.8%.
Multi-wall carbon nanotubes modified glassy carbon electrode (MWNT/GCE) was prepared,and the electrocatalysis of vitamin B12(VB12) and analytic conditions of VB12 on the electrode were studied.The results indicate that two pairs of redox peaks of VB12 at MWCNT/GCE are obtained by cyclic voltammetry in the mixture of 0.1 mol/L KCl as supporting electrolyte and phosphatic buffer solution (pH=7.0).The formal potentials are -0.10 V and -0.85 V (vs.SCE),respectively.The 1st order derivative of the current of reduction peak at -0.85 V is linearly related to the concentration of VB12 in the range of 1×10-8~4×10-7 mol/L,which obeys the equation i'p=5.958×10-7+2.885c(R=0.995) and the detection limit can reach to 1.5×10-9 mol/L.This electrode has been applied to directly determining VB12 in tablets with a recovery of 97.3%~107.8%.
2007, 24(8): 925-928
Abstract:
Five chiral β-amino alcohols were prepared from (S)-proline in an efficient manner and applied in the organocatalytic asymmetric epoxidation of α,β-enones.The effect of the catalyst structure,oxidant,solvent and reaction temperature on enantioselectivity was also studied.The results show that the catalyst structure,oxidant and solvent were important for the stereoselectivity and the conversion.However,the change in the enantioselectivity was not obvious when the reaction temperature was decreased from room temperature to -20℃.When tert-butyl hydroperoxide (TBHP) was used as the oxidant,and hexane as the solvent,at room temperature,(S)-2-(di-α-naphthylhydroxymethyl) pyrrolidine 2b was successfully applied in the organo-catalytic asymmetric epoxidation of α,β-enones with good yield and up to 84.6% enantiomeric excess.The structure of compound 4 was confirmed by 1H NMR,and the e.e.values were determined by HPLC analysis on chiral columns.
Five chiral β-amino alcohols were prepared from (S)-proline in an efficient manner and applied in the organocatalytic asymmetric epoxidation of α,β-enones.The effect of the catalyst structure,oxidant,solvent and reaction temperature on enantioselectivity was also studied.The results show that the catalyst structure,oxidant and solvent were important for the stereoselectivity and the conversion.However,the change in the enantioselectivity was not obvious when the reaction temperature was decreased from room temperature to -20℃.When tert-butyl hydroperoxide (TBHP) was used as the oxidant,and hexane as the solvent,at room temperature,(S)-2-(di-α-naphthylhydroxymethyl) pyrrolidine 2b was successfully applied in the organo-catalytic asymmetric epoxidation of α,β-enones with good yield and up to 84.6% enantiomeric excess.The structure of compound 4 was confirmed by 1H NMR,and the e.e.values were determined by HPLC analysis on chiral columns.
2007, 24(8): 929-932
Abstract:
The emulsifier-free emulsion polymerization of butylcyanoacrylate (BCA) was successfully carried out under the non-thermal effect of microwave irradiation.The morphologies and the sizes of the polybutylcyanoacrylate (PBCA) microspheres were characterized by TEM and PCS.The effects of citric acid concentration,monomer BCA concentration,and microwave power on the sizes of the PBCA microspheres were investigated.The results show that microwave irradiation could shorten the polymerization time,and the PBCA microspheres prepared by emulsifier-free emulsion polymerization under the non-thermal effect of microwave irradiation were smaller,more uniform than those obtained with conventional method.Under the same microwave power and monomer BCA concentration,the size of the PBCA microsphere increased with the increasing of the citric acid concentration.At the same citric acid concentration,the size of the PBCA microsphere decreased firstly and then increased with increasing the microwave power and the monomer BCA concentration.It was found that the microspheres with diameter almost 200 nm were obtained at a citric acid concentration of 0.005%,a monomer BCA concentration of 1.0%,and a microwave power of 600 W.
The emulsifier-free emulsion polymerization of butylcyanoacrylate (BCA) was successfully carried out under the non-thermal effect of microwave irradiation.The morphologies and the sizes of the polybutylcyanoacrylate (PBCA) microspheres were characterized by TEM and PCS.The effects of citric acid concentration,monomer BCA concentration,and microwave power on the sizes of the PBCA microspheres were investigated.The results show that microwave irradiation could shorten the polymerization time,and the PBCA microspheres prepared by emulsifier-free emulsion polymerization under the non-thermal effect of microwave irradiation were smaller,more uniform than those obtained with conventional method.Under the same microwave power and monomer BCA concentration,the size of the PBCA microsphere increased with the increasing of the citric acid concentration.At the same citric acid concentration,the size of the PBCA microsphere decreased firstly and then increased with increasing the microwave power and the monomer BCA concentration.It was found that the microspheres with diameter almost 200 nm were obtained at a citric acid concentration of 0.005%,a monomer BCA concentration of 1.0%,and a microwave power of 600 W.
2007, 24(8): 933-936
Abstract:
Two iron (hydr) oxides,goethite and akaganeite,were prepared by hydrolysis method.The adsorption of Cr(Ⅵ) on these iron (hydr) oxides from solution was investigated.Both goethite and akaganeite have a high efficiency for the removal of chromium.The adsorption process can be described by Langmuir isotherm model.The maximum adsorption capacities of α-FeO(OH) and β-FeO(OH) were 50.25 mg/g and 42.02 mg/g,respectively.For the solution samples with 10 mg/L Cr(Ⅵ),the residual Cr after treatment by both α-FeO(OH) and β-FeO(OH) can meet the safety standard for drinking water.The effect of coexistent ions on the adsorption was also studied.The presence at 200 mg/L Cl-,200 mg/L SO42- or 100 mg/L F- shows no obvious effect on the adsorption efficiency for Cr(Ⅵ).With the increase of ionic strength,the adsorption efficiency decreases.The presence of 100 mg/L H2PO4- and HCO3sup>- makes the removal efficiency of Cr(Ⅵ) decreased by 15%~20% for the same amount of adsorbent α-FeO(OH) or β-FeO(OH).
Two iron (hydr) oxides,goethite and akaganeite,were prepared by hydrolysis method.The adsorption of Cr(Ⅵ) on these iron (hydr) oxides from solution was investigated.Both goethite and akaganeite have a high efficiency for the removal of chromium.The adsorption process can be described by Langmuir isotherm model.The maximum adsorption capacities of α-FeO(OH) and β-FeO(OH) were 50.25 mg/g and 42.02 mg/g,respectively.For the solution samples with 10 mg/L Cr(Ⅵ),the residual Cr after treatment by both α-FeO(OH) and β-FeO(OH) can meet the safety standard for drinking water.The effect of coexistent ions on the adsorption was also studied.The presence at 200 mg/L Cl-,200 mg/L SO42- or 100 mg/L F- shows no obvious effect on the adsorption efficiency for Cr(Ⅵ).With the increase of ionic strength,the adsorption efficiency decreases.The presence of 100 mg/L H2PO4- and HCO3sup>- makes the removal efficiency of Cr(Ⅵ) decreased by 15%~20% for the same amount of adsorbent α-FeO(OH) or β-FeO(OH).
2007, 24(8): 937-940
Abstract:
Under supersonic condition Ce4+ may oxidize sulfur compound such as benzothiophene in diesel fuel into sulfonea.By choosing a proper solvent (DMF) to extract sulfonea,the sulfur content in diesel fuel is reduced from 554 mg/L to 25 mg/L with a desulfurization ratio of 95.5% and the sulfur content of diesel oil by oxidization is in line with the quality standard of diesel oil in World Fuel standard Ⅲ.The Ce4+ oxidation medium may be regenerated and be recycling by electrochemistry method and DMF is also regenerated and recycled.There are no wastes to discard with the best economic efficiency.And this desulfurization method is in accordance with the trend of development of green chemistry.Its best optimal operating conditions are reaction temperature 70℃;pH 0.69;oxidation time 50 min;volume ratio of diesel oil to water 1:9.The Ce4+ oxidation medium regenerate conditions are anode Pb;cathode C;voltage 3.1 V.The regenerated oxidation medium Ce4+ has the same desulfurization ability as the new one.
Under supersonic condition Ce4+ may oxidize sulfur compound such as benzothiophene in diesel fuel into sulfonea.By choosing a proper solvent (DMF) to extract sulfonea,the sulfur content in diesel fuel is reduced from 554 mg/L to 25 mg/L with a desulfurization ratio of 95.5% and the sulfur content of diesel oil by oxidization is in line with the quality standard of diesel oil in World Fuel standard Ⅲ.The Ce4+ oxidation medium may be regenerated and be recycling by electrochemistry method and DMF is also regenerated and recycled.There are no wastes to discard with the best economic efficiency.And this desulfurization method is in accordance with the trend of development of green chemistry.Its best optimal operating conditions are reaction temperature 70℃;pH 0.69;oxidation time 50 min;volume ratio of diesel oil to water 1:9.The Ce4+ oxidation medium regenerate conditions are anode Pb;cathode C;voltage 3.1 V.The regenerated oxidation medium Ce4+ has the same desulfurization ability as the new one.
2007, 24(8): 941-944
Abstract:
Chelating resins with thiourea groups in their main chains (PETU-Ⅰ~PETU-Ⅳ) were obtained the polyaddition of butyl bis (alkoxy carbonyl isothiocyanate) with diethylene triamine,triethylene tetraamine,tetraethylene pentamine,and polyethylene polyamine respectively.FTIR results show that the resins contain thiourea groups,and the resins show good thermal stability and swelling property.The adsorption of metal ions on PETU was investigated by batch tests.Adsorption capacities of the 4 kinds of resins for Au(Ⅲ) are 2.48,2.68,4.74 and 6.44 mmol/g respectively,those for Ag(Ⅰ) are 2.15,3.53,3.74 and 3.98 mmol/g respectively,and those for other ions such as Cu(Ⅱ) and Zn(Ⅱ) were below 0.36 mmol/g.The separation factors of PETU-Ⅳ for Au-Cu and Au-Zn are above 1 000,and that of PETU-Ⅱfor Ag-Cu and Ag-Zn are above 10,which justifies that PETU shows excellent adsorption and selectivity performance for Au(Ⅲ) and Ag(Ⅰ).The adsorption capacities of PETU decreased little in five adsorption-desorption cycles,which showed that PETU had good regeneration properties.
Chelating resins with thiourea groups in their main chains (PETU-Ⅰ~PETU-Ⅳ) were obtained the polyaddition of butyl bis (alkoxy carbonyl isothiocyanate) with diethylene triamine,triethylene tetraamine,tetraethylene pentamine,and polyethylene polyamine respectively.FTIR results show that the resins contain thiourea groups,and the resins show good thermal stability and swelling property.The adsorption of metal ions on PETU was investigated by batch tests.Adsorption capacities of the 4 kinds of resins for Au(Ⅲ) are 2.48,2.68,4.74 and 6.44 mmol/g respectively,those for Ag(Ⅰ) are 2.15,3.53,3.74 and 3.98 mmol/g respectively,and those for other ions such as Cu(Ⅱ) and Zn(Ⅱ) were below 0.36 mmol/g.The separation factors of PETU-Ⅳ for Au-Cu and Au-Zn are above 1 000,and that of PETU-Ⅱfor Ag-Cu and Ag-Zn are above 10,which justifies that PETU shows excellent adsorption and selectivity performance for Au(Ⅲ) and Ag(Ⅰ).The adsorption capacities of PETU decreased little in five adsorption-desorption cycles,which showed that PETU had good regeneration properties.
2007, 24(8): 945-948
Abstract:
CaSO4·2H2O whiskers in micrometer scale were prepared with CaCl2 and (NH4)2SO4 as the main raw materials via an ultrasonic process at room temperature.The product with better smoothness and higher aspect ratio was obtained.The method is friendly with environment and simple in manipulation under mild conditions.The effects of volume of anhydrous alcohol,concentration of hexadecyltrimethylammonium bromide (CTAB),ultrasonic time,heat-treatment and aging time on the morphology and size of CaSO4·2H2O were investigated in details.It has been found that the volume of anhydrous alcohol is important to the growth of CaSO4·2H2O whiskers.Anhydrous alcohol with excessive or insufficient volume is unfavorable to the preparation of the target product and the aspect ratio of CaSO4·2H2O whiskers is controlled by the concentration of CTAB.When the volume of anhydrous alcohol is 20 mL,the concentration of CTAB is 0.9 mmol/L and ultrasonic time is 1 h,the target product was prepared.The whisker became shiver,which coincide with the results of TG.Different from the general preparation process of inorganic compounds,aging time has no influence on the aspect ratio of CaSO4 whisker.The structure and thermostability of the product were characterized by X-ray diffraction and thermal gravimetric analysis,respectively.The growth mechanism of CaSO4·2H2O whiskers is discussed simply according to the experiment result.Some regulative rules of preparing CaSO4·2H2O whisker with high aspect ratio have been obtained.
CaSO4·2H2O whiskers in micrometer scale were prepared with CaCl2 and (NH4)2SO4 as the main raw materials via an ultrasonic process at room temperature.The product with better smoothness and higher aspect ratio was obtained.The method is friendly with environment and simple in manipulation under mild conditions.The effects of volume of anhydrous alcohol,concentration of hexadecyltrimethylammonium bromide (CTAB),ultrasonic time,heat-treatment and aging time on the morphology and size of CaSO4·2H2O were investigated in details.It has been found that the volume of anhydrous alcohol is important to the growth of CaSO4·2H2O whiskers.Anhydrous alcohol with excessive or insufficient volume is unfavorable to the preparation of the target product and the aspect ratio of CaSO4·2H2O whiskers is controlled by the concentration of CTAB.When the volume of anhydrous alcohol is 20 mL,the concentration of CTAB is 0.9 mmol/L and ultrasonic time is 1 h,the target product was prepared.The whisker became shiver,which coincide with the results of TG.Different from the general preparation process of inorganic compounds,aging time has no influence on the aspect ratio of CaSO4 whisker.The structure and thermostability of the product were characterized by X-ray diffraction and thermal gravimetric analysis,respectively.The growth mechanism of CaSO4·2H2O whiskers is discussed simply according to the experiment result.Some regulative rules of preparing CaSO4·2H2O whisker with high aspect ratio have been obtained.
2007, 24(8): 949-952
Abstract:
MnO2 with a high surface area of 177 m2/g as electrode for electrochemical capacitor was prepared with Ag foil as the catalyst at room temperature.The results of XRD and SEM showed that the MnO2 is α-MnO2 microspheres with cactus-like morphology composed of nanofibres.AC impedances,cyclic voltammetry and constant current charge-discharge tests indicated that α-MnO2 microspheres had an excellent electrochemical capacitance with the highest capacitance of 187.1 F/g and retained 90% of the initial capacity over 1 000 cycles within the potential range of 0~0.8 V versus SCE in 1 mol/L Na2SO4.
MnO2 with a high surface area of 177 m2/g as electrode for electrochemical capacitor was prepared with Ag foil as the catalyst at room temperature.The results of XRD and SEM showed that the MnO2 is α-MnO2 microspheres with cactus-like morphology composed of nanofibres.AC impedances,cyclic voltammetry and constant current charge-discharge tests indicated that α-MnO2 microspheres had an excellent electrochemical capacitance with the highest capacitance of 187.1 F/g and retained 90% of the initial capacity over 1 000 cycles within the potential range of 0~0.8 V versus SCE in 1 mol/L Na2SO4.
2007, 24(8): 953-956
Abstract:
By sol-gel in-situ polymerization method,a reactive hybrid sol was prepared with tetrethorylsilane (TEOS) as silicon source,vinyltrithorylsilane (VTEOS) as coupling agent via hydrolysis and condensation,then acrylic acid containing AIBN was added to it and polymerized in-situ.After being aged,continuous PAA/SiO2 hybrid fibers were prepared by drawing from this hybrid sol.The mechanism of hybrid reaction,spinnablity of the hybrid sol,structure and micromorphology and performance of the fiber were studied by FT-IR,TGA,SEM and experiment of immersion in water.The results show that the hybrid sol can be drawn into fibers when its viscosity become 1 400~3 000 mPa·s,its spinning time reaches 1 h,PAA was linked with SiO2 networks by chemical bonds.In the interior of the fiber,a homogeneous and continuous phase was formed by organic and inorganic components,and the hybrid fiber is better in resistance to heat and to water than pure PAA.
By sol-gel in-situ polymerization method,a reactive hybrid sol was prepared with tetrethorylsilane (TEOS) as silicon source,vinyltrithorylsilane (VTEOS) as coupling agent via hydrolysis and condensation,then acrylic acid containing AIBN was added to it and polymerized in-situ.After being aged,continuous PAA/SiO2 hybrid fibers were prepared by drawing from this hybrid sol.The mechanism of hybrid reaction,spinnablity of the hybrid sol,structure and micromorphology and performance of the fiber were studied by FT-IR,TGA,SEM and experiment of immersion in water.The results show that the hybrid sol can be drawn into fibers when its viscosity become 1 400~3 000 mPa·s,its spinning time reaches 1 h,PAA was linked with SiO2 networks by chemical bonds.In the interior of the fiber,a homogeneous and continuous phase was formed by organic and inorganic components,and the hybrid fiber is better in resistance to heat and to water than pure PAA.
2007, 24(8): 957-960
Abstract:
The sedimentation/demixing speed model of emulsion in gravitational field or centrifugal field was set up.The relationship between the conductivity and centrifugal time was obtained by accelerating the speed of sedimentation/demixing via centrifuging.The stable time (tc) of emulsion in centrifugal field could be achieved and the stable time (tg) of emulsion in gravitational field could also be calculated by means of the model.The centrifuge-conductance method has been developed to quickly evaluate the stability of O/W emulsion in this paper.For instance,the tc of emulsion A composed of 4% Pluronic F68,1.2% lecithin,8% mannite and 10% IPM was 22 min when the centrifugal speed was 8 000 r/min.According to the model,the tg was 69 d and the Centrifugal demixing constant (KA) was 48%.These data demonstrate that a stable O/W emulsion can be formed using the above mentioned formulation.
The sedimentation/demixing speed model of emulsion in gravitational field or centrifugal field was set up.The relationship between the conductivity and centrifugal time was obtained by accelerating the speed of sedimentation/demixing via centrifuging.The stable time (tc) of emulsion in centrifugal field could be achieved and the stable time (tg) of emulsion in gravitational field could also be calculated by means of the model.The centrifuge-conductance method has been developed to quickly evaluate the stability of O/W emulsion in this paper.For instance,the tc of emulsion A composed of 4% Pluronic F68,1.2% lecithin,8% mannite and 10% IPM was 22 min when the centrifugal speed was 8 000 r/min.According to the model,the tg was 69 d and the Centrifugal demixing constant (KA) was 48%.These data demonstrate that a stable O/W emulsion can be formed using the above mentioned formulation.
2007, 24(8): 961-964
Abstract:
2-Arylglutarates with high yields (73%~87%) were prepared by addition-rearrangement reactions of phenylsulfonylacetates containing 4-nitro or 2-nitro with α,β-unsaturated esters under K2CO3-TEBA phase transfer catalyst conditions.The effects of substistution groups at the phenyl ring of reactant-arylsulfonylacetates on the addition-rearrangement reaction were examined.Arylsulfonylacetate containing 4-nitro or 2-nitro at the phenyl ring was found to carry out the addition-rearrangement reaction to form 2-arylglutarates under K2CO3-TEBA phase transfer catalyst conditions.The mechanism is proposed that the Michael adduct reactions of arylsulfonylacetates with α,β-unsaturated esters resulted in the Michael adducts,which might rearrange to the inter mediate through intramolecular nucleophilic substitution,which might further lose sulfur dioxide and then led to 2-arylglutarates.The Michael adduct reactions of arylsulfonylacetates containing electron-donating groups (for example:methyl) or weakly absorbing groups (for example:chloro) at 4-position or 2-position of the phenyl ring with α,β-unsaturated esters normally resulted in 2-arylsulfonylacetates.
2-Arylglutarates with high yields (73%~87%) were prepared by addition-rearrangement reactions of phenylsulfonylacetates containing 4-nitro or 2-nitro with α,β-unsaturated esters under K2CO3-TEBA phase transfer catalyst conditions.The effects of substistution groups at the phenyl ring of reactant-arylsulfonylacetates on the addition-rearrangement reaction were examined.Arylsulfonylacetate containing 4-nitro or 2-nitro at the phenyl ring was found to carry out the addition-rearrangement reaction to form 2-arylglutarates under K2CO3-TEBA phase transfer catalyst conditions.The mechanism is proposed that the Michael adduct reactions of arylsulfonylacetates with α,β-unsaturated esters resulted in the Michael adducts,which might rearrange to the inter mediate through intramolecular nucleophilic substitution,which might further lose sulfur dioxide and then led to 2-arylglutarates.The Michael adduct reactions of arylsulfonylacetates containing electron-donating groups (for example:methyl) or weakly absorbing groups (for example:chloro) at 4-position or 2-position of the phenyl ring with α,β-unsaturated esters normally resulted in 2-arylsulfonylacetates.
2007, 24(8): 965-967
Abstract:
The interaction of cetyltrimethylammonium bromide (CTAB) with bovine serum albumin (BSA) was investigated by fluorescence spectroscopy and synchronous fluorescence under simulative physiological conditions.In the mechanism study,it shows that the fluorescence quenching of BSA by CTAB is static quenching together with the formation of a complex of BSA and CTAB.The binding constant KA(305 K:7.09×104 L/mol;310 K:4.97×104 L/mol) and thermodynamic parameters (ΔH=-55.85 kJ/mol;ΔS=-90.26 J/(mol·K)/-90.55 J/(mol·K);ΔG=-28.32(kJ/mol)/-27.87(kJ/mol) at different temperatures were calculated according to Lineweaver-Burk equation.The thermodynamic paramters show hydrogen bond and Van der Waals interactions play important roles to stabilize the complex.The result of synchronous fluorescence indicates that the polarity around the tryptophan residues has decreased and the hydrophobicity has increased.
The interaction of cetyltrimethylammonium bromide (CTAB) with bovine serum albumin (BSA) was investigated by fluorescence spectroscopy and synchronous fluorescence under simulative physiological conditions.In the mechanism study,it shows that the fluorescence quenching of BSA by CTAB is static quenching together with the formation of a complex of BSA and CTAB.The binding constant KA(305 K:7.09×104 L/mol;310 K:4.97×104 L/mol) and thermodynamic parameters (ΔH=-55.85 kJ/mol;ΔS=-90.26 J/(mol·K)/-90.55 J/(mol·K);ΔG=-28.32(kJ/mol)/-27.87(kJ/mol) at different temperatures were calculated according to Lineweaver-Burk equation.The thermodynamic paramters show hydrogen bond and Van der Waals interactions play important roles to stabilize the complex.The result of synchronous fluorescence indicates that the polarity around the tryptophan residues has decreased and the hydrophobicity has increased.
2007, 24(8): 968-970
Abstract:
The essential oil from Malania Olceifera Chum was extracted by steam distillation,and the chemical components were identified and determined by gas chromatography-mass spectrometry (GC-MS) method.The results show that the yield of essential oil was 1.3% from peel and flesh of Malania Olceifera Chum,and 6 compounds (99.37%) of 10 chromatographic components in the oil were identified.The major constituents include benzaldehyde (78.79%),benzyl alcohol (14.69%),mandelonitrile (4.74%),benzoic acid (0.15%),benzyl benzoate (0.12%),α-cyanobenzyl benzoate (0.88%).The yield of oil extracted from the branches and leaves was 0.3%,which contains 6 chromatographic components and 4 compounds (99.6%) in that were identified,the major components were benzaldehyde (61.88%),benzyl alcohol (1.51%),mandelonitrile (24.80%) and benzoic acid (11.32%).The yield of benzaldehyde was 80.8%,purity was 98% by vacuum rectification in N2.
The essential oil from Malania Olceifera Chum was extracted by steam distillation,and the chemical components were identified and determined by gas chromatography-mass spectrometry (GC-MS) method.The results show that the yield of essential oil was 1.3% from peel and flesh of Malania Olceifera Chum,and 6 compounds (99.37%) of 10 chromatographic components in the oil were identified.The major constituents include benzaldehyde (78.79%),benzyl alcohol (14.69%),mandelonitrile (4.74%),benzoic acid (0.15%),benzyl benzoate (0.12%),α-cyanobenzyl benzoate (0.88%).The yield of oil extracted from the branches and leaves was 0.3%,which contains 6 chromatographic components and 4 compounds (99.6%) in that were identified,the major components were benzaldehyde (61.88%),benzyl alcohol (1.51%),mandelonitrile (24.80%) and benzoic acid (11.32%).The yield of benzaldehyde was 80.8%,purity was 98% by vacuum rectification in N2.
2007, 24(8): 971-973
Abstract:
A synthetic process of adenosine was performed from inosine by a conversion of functional groups with an overall yield of 62%.With sodium acetate as catalyst,inosine was esterified with acetic anhydride in the yield of 92% to give 2',3',5'-triacetyl inosine,which was treated with pyridine and phosphorus oxychloride to form a pyridinium solution,followed by performing an amination at 40℃ and 0.25~0.30 MPa to achieve adenosine in the yield of 67%.The structure of adenosine was confirmed by means of 1H NMR,MS.This simple synthesis of adenosine is accessible to an industrial scale.
A synthetic process of adenosine was performed from inosine by a conversion of functional groups with an overall yield of 62%.With sodium acetate as catalyst,inosine was esterified with acetic anhydride in the yield of 92% to give 2',3',5'-triacetyl inosine,which was treated with pyridine and phosphorus oxychloride to form a pyridinium solution,followed by performing an amination at 40℃ and 0.25~0.30 MPa to achieve adenosine in the yield of 67%.The structure of adenosine was confirmed by means of 1H NMR,MS.This simple synthesis of adenosine is accessible to an industrial scale.
2007, 24(8): 974-976
Abstract:
Direct methanol fuel cell (DMFC) has attracted more and more attention due to its many advantages.However,DMFC has some main problems that prevent its practical application.One of the problems of DMFC is the low electrocatalytic activity of its cathodic Pt catalyst for the oxygen reduction.The present paper covers carbon-supported tetra-phenyl cobalt porphyrin (CoTPP) and Pt(CoTPP-Pt/C) catalysts prepared.The electrochemical measurements demonstrate that the electrocatalytic activity of CoTPP-Pt/C catalyst for the oxygen reduction is higher than that of carbon supported Pt(Pt/C) catalyst.The current density of the oxygen reduction at CoTPP-Pt/C catalyst is about 30% higher than that of Pt/C catalyst.However,the methanol resistant ability of the CoTPP-Pt/C catalyst is similar to that of Pt/C catalyst.Thus,it should be improved.
Direct methanol fuel cell (DMFC) has attracted more and more attention due to its many advantages.However,DMFC has some main problems that prevent its practical application.One of the problems of DMFC is the low electrocatalytic activity of its cathodic Pt catalyst for the oxygen reduction.The present paper covers carbon-supported tetra-phenyl cobalt porphyrin (CoTPP) and Pt(CoTPP-Pt/C) catalysts prepared.The electrochemical measurements demonstrate that the electrocatalytic activity of CoTPP-Pt/C catalyst for the oxygen reduction is higher than that of carbon supported Pt(Pt/C) catalyst.The current density of the oxygen reduction at CoTPP-Pt/C catalyst is about 30% higher than that of Pt/C catalyst.However,the methanol resistant ability of the CoTPP-Pt/C catalyst is similar to that of Pt/C catalyst.Thus,it should be improved.
