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2006 Volume 23 Issue 10
2006, 23(10): 1069-1075
Abstract:
Photo-induced electron transfer(PET) is a crucial photophysical process for the design of fluorescence chemosensors.Various fluorescence molecular switches for metal ions,protons and small molecules have been designed and developed based on the variation of fluorescence intensity in the PET process.Compared to the traditional ones,those fluorescence chemosensors have a number of advantages in terms of response time and convenience in use.In addition,logic gates of different functions can be achieved via the design of the molecular switches.These molecular switches can be the basis for the design of molecular devices,molecular computers,and other complex molecular machines.In the present paper,recent development in fluorescence molecular switches based on PET process is reviewed,and its potential applications are proposed.
Photo-induced electron transfer(PET) is a crucial photophysical process for the design of fluorescence chemosensors.Various fluorescence molecular switches for metal ions,protons and small molecules have been designed and developed based on the variation of fluorescence intensity in the PET process.Compared to the traditional ones,those fluorescence chemosensors have a number of advantages in terms of response time and convenience in use.In addition,logic gates of different functions can be achieved via the design of the molecular switches.These molecular switches can be the basis for the design of molecular devices,molecular computers,and other complex molecular machines.In the present paper,recent development in fluorescence molecular switches based on PET process is reviewed,and its potential applications are proposed.
2006, 23(10): 1076-1080
Abstract:
N,O-Carboxymethyl chitosan(CMC)(Mw=3.08×105) with 1.84% carboxymethyl substitution was synthesized and used as an organic matrix to induce and control the nucleation and growth of CaCO3 crystals in aqueous solution,and the obtained CaCO3 particles were characterized by FT-IR,UV,TEM and XRD.The results show that CMCs regulated the formation of the particles and led to vaterite nano-crystals.When the CMC concentration was 5.0,2.0,1.4,1.1 and 0.8 g/L,the average diameter of the obtained CaCO3 particles was 15,20,50,150 and 100 nm,respectively.It could be concluded that the particles became smaller with the increase of the CMC concentration when the CMC concentration varied within the range of 5.0~1.1 g/L.Meanwhile,the CaCO3nanoparticles were stabilized by the adsorbed CMC molecules.
N,O-Carboxymethyl chitosan(CMC)(Mw=3.08×105) with 1.84% carboxymethyl substitution was synthesized and used as an organic matrix to induce and control the nucleation and growth of CaCO3 crystals in aqueous solution,and the obtained CaCO3 particles were characterized by FT-IR,UV,TEM and XRD.The results show that CMCs regulated the formation of the particles and led to vaterite nano-crystals.When the CMC concentration was 5.0,2.0,1.4,1.1 and 0.8 g/L,the average diameter of the obtained CaCO3 particles was 15,20,50,150 and 100 nm,respectively.It could be concluded that the particles became smaller with the increase of the CMC concentration when the CMC concentration varied within the range of 5.0~1.1 g/L.Meanwhile,the CaCO3nanoparticles were stabilized by the adsorbed CMC molecules.
2006, 23(10): 1081-1084
Abstract:
The effect of alcohol on microemulsions composed of Triton X-100,cyclohexane,co-surfactant and water was studied by means of emulsion breaking temperature,size distribution of nanosized silica,and TEM determination.It was found that interfacial film strength is closely related to the alcohol chain length,and branched isomers.In particular,the chain length of 1-octanol matches well with that of TX-100,so its interfacial film strength was highest,leading to the most number of micelle and optimum dispersion for preparing nanosized silica.For other alcohols,the chain length of 1-dodecanol exceeded the effective length of TX-100 the most,so its interfacial film strength was minimum, resulting in the worst dispersion of nanosized silica.Branched alcohol isomers formed U system easily,resulting in the decrease of the number of micelle and agglomeration of nanosized silica.
The effect of alcohol on microemulsions composed of Triton X-100,cyclohexane,co-surfactant and water was studied by means of emulsion breaking temperature,size distribution of nanosized silica,and TEM determination.It was found that interfacial film strength is closely related to the alcohol chain length,and branched isomers.In particular,the chain length of 1-octanol matches well with that of TX-100,so its interfacial film strength was highest,leading to the most number of micelle and optimum dispersion for preparing nanosized silica.For other alcohols,the chain length of 1-dodecanol exceeded the effective length of TX-100 the most,so its interfacial film strength was minimum, resulting in the worst dispersion of nanosized silica.Branched alcohol isomers formed U system easily,resulting in the decrease of the number of micelle and agglomeration of nanosized silica.
2006, 23(10): 1085-1089
Abstract:
Molecularly imprinted polymers(MIPs) were synthesized via thermal polymerization method with levofloxacin(LVFX) as template and methyacrylic acid as functional monomer.The UV and IR spectra indicated that the MIPs could recognize LVFX molecule through hydrogen-bond and ionic-bond interactions.Scatchard analysis showed that two kinds of recognition sites were formed,and the maximum apparent binding capacities were 9.76 μmol/g and 25.75 μmol/g,respectively.The selective adsorption of LVFX on MIPs could be completed in 10 min.On the basis of isothermal binding thermodynamics,the absorption to the template was spontaneous,and ΔΔH=-1.18 kJ/mol and ΔΔS=-0.27 J/(mol·K).
Molecularly imprinted polymers(MIPs) were synthesized via thermal polymerization method with levofloxacin(LVFX) as template and methyacrylic acid as functional monomer.The UV and IR spectra indicated that the MIPs could recognize LVFX molecule through hydrogen-bond and ionic-bond interactions.Scatchard analysis showed that two kinds of recognition sites were formed,and the maximum apparent binding capacities were 9.76 μmol/g and 25.75 μmol/g,respectively.The selective adsorption of LVFX on MIPs could be completed in 10 min.On the basis of isothermal binding thermodynamics,the absorption to the template was spontaneous,and ΔΔH=-1.18 kJ/mol and ΔΔS=-0.27 J/(mol·K).
2006, 23(10): 1090-1093
Abstract:
The synthesis of 1,5-bis-(3-nitrophenyl)-1,4-pentadien-3-one though the Claisen-Schmidt condensation between 3-nitrobenzaldehyde and acetone was performed in methanol under ultrasound in the presence of anhydrous K2CO3.The results show that the best reaction conditions are that the molar ratio of 3-nitrobenzaldehyde vs acetone is 2,amount of methanol 3 mL,the molar ratio of anhydrous K2CO3 vs 3-nitrobenzaldehyde 0.4,the reaction is performed at 33℃ for 20 min in a 450 W ultrasound cleaner,and the yield is over 88%.Compared with previous methods in the literature,the present procedure has the advaotages of shorter reaction time,easier work-up,milder conditions and higher yields.
The synthesis of 1,5-bis-(3-nitrophenyl)-1,4-pentadien-3-one though the Claisen-Schmidt condensation between 3-nitrobenzaldehyde and acetone was performed in methanol under ultrasound in the presence of anhydrous K2CO3.The results show that the best reaction conditions are that the molar ratio of 3-nitrobenzaldehyde vs acetone is 2,amount of methanol 3 mL,the molar ratio of anhydrous K2CO3 vs 3-nitrobenzaldehyde 0.4,the reaction is performed at 33℃ for 20 min in a 450 W ultrasound cleaner,and the yield is over 88%.Compared with previous methods in the literature,the present procedure has the advaotages of shorter reaction time,easier work-up,milder conditions and higher yields.
Effect of Silica Nano-Particles on the Crystallization of Nylon-66 in Nylon-66/silica Nanocomposites
2006, 23(10): 1094-1098
Abstract:
Nylon66/silica nanocomposites were prepared on a twin-screw extruder.The crystallization behavior of nylon66 and the nanocompsites was studied by X-ray diffraction(XRD) and differential scanning calorimetry(DSC).The none-isothermal crystallization behavior of the nanocomposites was also discussed by revised Avrami method.It shows that nano-silica acted as the nucleating agent in nylon crystallization,and increased the crystallization rate of the nylon.
Nylon66/silica nanocomposites were prepared on a twin-screw extruder.The crystallization behavior of nylon66 and the nanocompsites was studied by X-ray diffraction(XRD) and differential scanning calorimetry(DSC).The none-isothermal crystallization behavior of the nanocomposites was also discussed by revised Avrami method.It shows that nano-silica acted as the nucleating agent in nylon crystallization,and increased the crystallization rate of the nylon.
2006, 23(10): 1099-1103
Abstract:
An amperometric biosensor for the determination of organophosphorus and carbamate pesticides is described.Acetylcholinesterase(AChE) immobilized on regenerated silk fibroin powder was thoroughly mixed with graphite powder,non-conducting epoxy resin,and electronic mediator 7,7,8,8-tetracyanoquinodimethane(TCNQ) to prepare the biosensor.The preparation conditions of the biosensor were optimized.The proposed method exhibited a good reproducibility and recovery ratio.The inhibition versus the logarithm of concentration was linear to omethoate and carbofuran over the concentration ranges of 5.0×10-5 g/L to 5.0×10-3 mg/L and 5.0×10-5 g/L to 1.0 mg/L with the detection limits of 1.9×10-5 mg/L and 4.7×10-5 mg/L,respectively.
An amperometric biosensor for the determination of organophosphorus and carbamate pesticides is described.Acetylcholinesterase(AChE) immobilized on regenerated silk fibroin powder was thoroughly mixed with graphite powder,non-conducting epoxy resin,and electronic mediator 7,7,8,8-tetracyanoquinodimethane(TCNQ) to prepare the biosensor.The preparation conditions of the biosensor were optimized.The proposed method exhibited a good reproducibility and recovery ratio.The inhibition versus the logarithm of concentration was linear to omethoate and carbofuran over the concentration ranges of 5.0×10-5 g/L to 5.0×10-3 mg/L and 5.0×10-5 g/L to 1.0 mg/L with the detection limits of 1.9×10-5 mg/L and 4.7×10-5 mg/L,respectively.
2006, 23(10): 1104-1107
Abstract:
Fluorinated polyurethane(FPU) emulsion was synthesized via copolymerization of fluorinated polyol,isophorone diisocyanate(IPDI),poly(1,4-butylene adipate) glycol(PBA),dimethlylol propionic acid(DMPA) and trimethylol propane(TMP).The extent of micro-phase separation in FPU film and the surface properties of the FPU film were studied.The results show that the extent of the micro-phase separation in the FPU increases with fluorine content.A layer of 150~200 μm thick from the surface is rich in fluorinated chains in the fluorinated polyurethane film.The water contact angle of the FPU dry films becomes significantly greater than that of polyurethane.The water(contact) angle was 70° when ω(DFA) was 1%.The water resistence becomes better.
Fluorinated polyurethane(FPU) emulsion was synthesized via copolymerization of fluorinated polyol,isophorone diisocyanate(IPDI),poly(1,4-butylene adipate) glycol(PBA),dimethlylol propionic acid(DMPA) and trimethylol propane(TMP).The extent of micro-phase separation in FPU film and the surface properties of the FPU film were studied.The results show that the extent of the micro-phase separation in the FPU increases with fluorine content.A layer of 150~200 μm thick from the surface is rich in fluorinated chains in the fluorinated polyurethane film.The water contact angle of the FPU dry films becomes significantly greater than that of polyurethane.The water(contact) angle was 70° when ω(DFA) was 1%.The water resistence becomes better.
2006, 23(10): 1108-1111
Abstract:
An asymmetrical double Schiff base Cu(Ⅱ) mononuclear complex HCuLe (Where H3Le is N-3-carboxylsalicylidene-N'-(5-chlorosalicylaldehyde-1,2-diaminoethane)) and its trinuclear complexes Cu(Ⅱ)M(Ⅱ)Cu(Ⅱ)(M=Co,Cu) were synthesized and characterized by means of elemental analysis,IR and electron spectrometries.The variable-temperature magnetic susceptibilities of(CuLe)2Co·H2O and (CuLe)2Cu·H2O at 5~300 K were analyzed by means of the Hamiltonian Ĥ=-2JŜM(ŜCu1+ŜCu2),leading to J1=-15.1 cm-1,J2=-61.8 cm-1,which indicated that the interaction between the central M(Ⅱ) ion and the terminal Cu(Ⅱ) ions was antiferromagnetical.
An asymmetrical double Schiff base Cu(Ⅱ) mononuclear complex HCuLe (Where H3Le is N-3-carboxylsalicylidene-N'-(5-chlorosalicylaldehyde-1,2-diaminoethane)) and its trinuclear complexes Cu(Ⅱ)M(Ⅱ)Cu(Ⅱ)(M=Co,Cu) were synthesized and characterized by means of elemental analysis,IR and electron spectrometries.The variable-temperature magnetic susceptibilities of(CuLe)2Co·H2O and (CuLe)2Cu·H2O at 5~300 K were analyzed by means of the Hamiltonian Ĥ=-2JŜM(ŜCu1+ŜCu2),leading to J1=-15.1 cm-1,J2=-61.8 cm-1,which indicated that the interaction between the central M(Ⅱ) ion and the terminal Cu(Ⅱ) ions was antiferromagnetical.
2006, 23(10): 1112-1115
Abstract:
A catalytic polarographic determination of fenbufen(FBF) in the presence of K2S2O8 was(described).In 0.2 mol/L HAc-NaAc(pH=5.0) buffer,the polarographic reduction of carbonyl group of FBF yielded an irreversible reduction wave at a peak potential Ep of-1.18 V(vs.SCE).When 4×10-4 mol/L K2S2O8 was present in the buffer,the reduced FBF intermediate was oxidized by persulfate,producing a catalytic wave at the original potential.The analytical sensitivity of the catalytic wave was 10 times higher than that of the corresponding reduction wave.The peak current of the catalytic wave varied linearly with the FBF concentration over the range from 7.08×10-6 mol/L to 2.36×10-5 mol/L(r=0.993 1,n=7) and from 2.36×10-8 mol/L to 7.08×10-6 mol/L(r=0.998 9,n=8) with a detection limit of 7.78×10-9 mol/L(3σ).RSD(n=11) was 1.2% at the concentration level of 4.72×10-7 mol/L.The proposed method was applied to the determination of FBF in the raw material,in tablets and in capsules without previous treatment.
A catalytic polarographic determination of fenbufen(FBF) in the presence of K2S2O8 was(described).In 0.2 mol/L HAc-NaAc(pH=5.0) buffer,the polarographic reduction of carbonyl group of FBF yielded an irreversible reduction wave at a peak potential Ep of-1.18 V(vs.SCE).When 4×10-4 mol/L K2S2O8 was present in the buffer,the reduced FBF intermediate was oxidized by persulfate,producing a catalytic wave at the original potential.The analytical sensitivity of the catalytic wave was 10 times higher than that of the corresponding reduction wave.The peak current of the catalytic wave varied linearly with the FBF concentration over the range from 7.08×10-6 mol/L to 2.36×10-5 mol/L(r=0.993 1,n=7) and from 2.36×10-8 mol/L to 7.08×10-6 mol/L(r=0.998 9,n=8) with a detection limit of 7.78×10-9 mol/L(3σ).RSD(n=11) was 1.2% at the concentration level of 4.72×10-7 mol/L.The proposed method was applied to the determination of FBF in the raw material,in tablets and in capsules without previous treatment.
2006, 23(10): 1116-1119
Abstract:
Natural cellulose in farm by-products such as bagasse or straw stalk was choosen as the material.After epoxy straw cellulose was treated with polyamines,polyamine straw cellulose spheres(SS-MB-TVTA,SS-MB-TEPA,SS-MB-TMDA) with good hydrodynamic and mechanical performance were prepared.They can adsorb heavy metals ions from water(for example,the static adsorption capacity of three kinds of polyamine straw cellulose spheres for Zn2+ were 17.58,4.04,and 6.54 mg/g,respectively).SS-MB-TVTA with better hydrodynamic property was chosen to prepare separation columns,which was applied to enrich and separate Zn2+.A method of analyzing trace amount of zinc in water after enrichment on SS-MB-TVTA by FAAS was established,and the Zn2+ concentrations in the water of Xihe River and Jialingjiang River were determined.
Natural cellulose in farm by-products such as bagasse or straw stalk was choosen as the material.After epoxy straw cellulose was treated with polyamines,polyamine straw cellulose spheres(SS-MB-TVTA,SS-MB-TEPA,SS-MB-TMDA) with good hydrodynamic and mechanical performance were prepared.They can adsorb heavy metals ions from water(for example,the static adsorption capacity of three kinds of polyamine straw cellulose spheres for Zn2+ were 17.58,4.04,and 6.54 mg/g,respectively).SS-MB-TVTA with better hydrodynamic property was chosen to prepare separation columns,which was applied to enrich and separate Zn2+.A method of analyzing trace amount of zinc in water after enrichment on SS-MB-TVTA by FAAS was established,and the Zn2+ concentrations in the water of Xihe River and Jialingjiang River were determined.
2006, 23(10): 1120-1123
Abstract:
The surface modification of polystyrene films via selective aggregation of polyether silicone oil(PSO) on their surfaces was studied.Because of the surface activity of the silicone oil chain segments,the(selective) migration of PSO was greatly increased.Owing to the good hydrophilicity of the polyether chain segments,the surface free energy(γ) of the blends was enhanced by 180%,and the polar portion of its γ increased nine times.Attenuated total reflectance Fourier transform infrared spectroscopy(ATR-FTIR) and contact angle measurement were used to detect the surface structure and surface properties.It was found that the influence of contact medium on the selective migration of polyether silicone oil was important.Glass substrate can induce more polyether chain segments to segregate at the polystyrene/substrate interface and air can induce more silicon oil chain segments to the polymer surface.
The surface modification of polystyrene films via selective aggregation of polyether silicone oil(PSO) on their surfaces was studied.Because of the surface activity of the silicone oil chain segments,the(selective) migration of PSO was greatly increased.Owing to the good hydrophilicity of the polyether chain segments,the surface free energy(γ) of the blends was enhanced by 180%,and the polar portion of its γ increased nine times.Attenuated total reflectance Fourier transform infrared spectroscopy(ATR-FTIR) and contact angle measurement were used to detect the surface structure and surface properties.It was found that the influence of contact medium on the selective migration of polyether silicone oil was important.Glass substrate can induce more polyether chain segments to segregate at the polystyrene/substrate interface and air can induce more silicon oil chain segments to the polymer surface.
2006, 23(10): 1124-1128
Abstract:
The silylated mesoporous molecular sieve was prepared via the organic-silylation of a pure silica KIT-1 with trimethylchlorosilane and dichlorodimethylsilane at 30℃ for 8 h,and characterized by means of FT-IR,XRD and nitrogen adsorption-desorption techniques.The FT-IR spectra show that the trimethylsilyl groups have been grafted to the surface of molecular sieve.Compared to the parent sieve,the resultant samples keep the original mesoporous structure with less specific BET surface area and BJH volume and smaller diameter of pores and show a higher stability toward water(boiling in water for 48 h,the sieve still remained the original mesoporous structure).The hydrophobicity of the sieve modified by trimethylchlorosilane is better than that of the one modified by dichlorodimethylsilane,its adsorption capacity for mixed cresol in dilution is 0.512 mmol/g.
The silylated mesoporous molecular sieve was prepared via the organic-silylation of a pure silica KIT-1 with trimethylchlorosilane and dichlorodimethylsilane at 30℃ for 8 h,and characterized by means of FT-IR,XRD and nitrogen adsorption-desorption techniques.The FT-IR spectra show that the trimethylsilyl groups have been grafted to the surface of molecular sieve.Compared to the parent sieve,the resultant samples keep the original mesoporous structure with less specific BET surface area and BJH volume and smaller diameter of pores and show a higher stability toward water(boiling in water for 48 h,the sieve still remained the original mesoporous structure).The hydrophobicity of the sieve modified by trimethylchlorosilane is better than that of the one modified by dichlorodimethylsilane,its adsorption capacity for mixed cresol in dilution is 0.512 mmol/g.
2006, 23(10): 1129-1134
Abstract:
P(NIPAAm-co-AAm) and interpenetrating polymer network(IPN) hydrogels,PAAc/P(NIPAAm-co-AAm) with different compositions were prepared from acrylic acid(AAc),N-isopropylacrylamide(NIPAAm),and acrylamide(AAm) through free radical polymerization,in which N,N'-methylenebisacry-lamide(BIS) was used as a crosslinking agent.The swelling and drug releasing properties of these hydrogels with different thermosensitive properties were studied.The influence of the amount of AAm on the properties of these hydrogels was investigated.Experimental results revealed that these copolymer gels showed negative temperature sensitivity.When the molar ratio of AAm to NIPAm increased to 3:1 from 1:3,the effective crosslinking density of the copolymer gels increased to 3.071×10-6 mol/cm3 from 2.518×10-6 mol/cm3,and the equilibrium swelling ratio decreased to 15.36 from 18.65;thermosensitivity became weaker,and sodium salicylate releasing ratio of the copolymer gels reduced from 95.30% to 75.55%,and salicylic acid releasing ratio increased from 29.87% to 66.12%.However,IPN gels showed positive temperature sensitivity.With increasing the molar ratio of AAm to NIPAm from 1:3 to 3:1,the effective crosslinking density of IPN gels decreased from 31.06×10-6 mol/cm3 to 26.92×10-6 mol/cm3,and the equilibrium swelling ratio increased to 8.792 from 1.816;thermosensitivity of the IPN gels increased,and sodium salicylate releasing ratio increased from 41.56% to 59.65%,and salicylic acid releasing ratio also increased from 43.77% to 66.55%.
P(NIPAAm-co-AAm) and interpenetrating polymer network(IPN) hydrogels,PAAc/P(NIPAAm-co-AAm) with different compositions were prepared from acrylic acid(AAc),N-isopropylacrylamide(NIPAAm),and acrylamide(AAm) through free radical polymerization,in which N,N'-methylenebisacry-lamide(BIS) was used as a crosslinking agent.The swelling and drug releasing properties of these hydrogels with different thermosensitive properties were studied.The influence of the amount of AAm on the properties of these hydrogels was investigated.Experimental results revealed that these copolymer gels showed negative temperature sensitivity.When the molar ratio of AAm to NIPAm increased to 3:1 from 1:3,the effective crosslinking density of the copolymer gels increased to 3.071×10-6 mol/cm3 from 2.518×10-6 mol/cm3,and the equilibrium swelling ratio decreased to 15.36 from 18.65;thermosensitivity became weaker,and sodium salicylate releasing ratio of the copolymer gels reduced from 95.30% to 75.55%,and salicylic acid releasing ratio increased from 29.87% to 66.12%.However,IPN gels showed positive temperature sensitivity.With increasing the molar ratio of AAm to NIPAm from 1:3 to 3:1,the effective crosslinking density of IPN gels decreased from 31.06×10-6 mol/cm3 to 26.92×10-6 mol/cm3,and the equilibrium swelling ratio increased to 8.792 from 1.816;thermosensitivity of the IPN gels increased,and sodium salicylate releasing ratio increased from 41.56% to 59.65%,and salicylic acid releasing ratio also increased from 43.77% to 66.55%.
2006, 23(10): 1135-1139
Abstract:
Ag-doped nano-BaTiO3 powder was prepared by Sol-gel method from Ba(CH3COO)2,Ti(OC4H9)4 and AgNO3.The effects of pH value,calcining temperature and calcining time on the structure,morphology and antibacterial properties of Ag-doped nano-BaTiO3 were investigated.The microcrystallite was also characterized by XRD,SEM and particle analysis technique.The results show that optimized preparation condition should be pH=3.5,calcinated for 2 hours at temperature 800℃.Ag-doped nano-BaTiO3 powder has better uniformity and dispersibility prerovskite-type structure of cubic system.The particle analysis technique shows that particle diameter is the range of while preserving 40~100 nm and the mean particle diameters is around 65 nm.Ag-doped nano-BaTiO3 powder has distinctive antibacterial activities to Staphylocouus aureusand,Escherichia coi and Pseudomonas aeruginosa.The inhibition diameters are 20.0,19.5 and 15.7 mm respectively based cylinder plate assay.
Ag-doped nano-BaTiO3 powder was prepared by Sol-gel method from Ba(CH3COO)2,Ti(OC4H9)4 and AgNO3.The effects of pH value,calcining temperature and calcining time on the structure,morphology and antibacterial properties of Ag-doped nano-BaTiO3 were investigated.The microcrystallite was also characterized by XRD,SEM and particle analysis technique.The results show that optimized preparation condition should be pH=3.5,calcinated for 2 hours at temperature 800℃.Ag-doped nano-BaTiO3 powder has better uniformity and dispersibility prerovskite-type structure of cubic system.The particle analysis technique shows that particle diameter is the range of while preserving 40~100 nm and the mean particle diameters is around 65 nm.Ag-doped nano-BaTiO3 powder has distinctive antibacterial activities to Staphylocouus aureusand,Escherichia coi and Pseudomonas aeruginosa.The inhibition diameters are 20.0,19.5 and 15.7 mm respectively based cylinder plate assay.
2006, 23(10): 1140-1144
Abstract:
Ligand free Ullmann coupling reactions of aryl halides catalyzed by Pd/C were studied in O/W Triton X10 microemulsion(ME) in comparison with biphase systems.The yield of biphenyl in a Triton X10 ME system was found higher than that in the biphase system.The reactivities in different ME were also studied.The amount of sodium formate,base type,the amount of Pd/C,temperature on the conversion and selectivity of the coupling reaction were investigated.High conversion(up to 100%) and selectivity(up to 98%) of the reaction could be achieved when 10%(molar fraction) sodium fomate,2%(molar fraction) Pd/C,potassium carbonate and sodium hydroxide as base,80℃ reaction temperature and tetrabutylammo-nium chloride were used.Therefore,the microemulsion is an alternative reaction medium for Ullmann reaction.
Ligand free Ullmann coupling reactions of aryl halides catalyzed by Pd/C were studied in O/W Triton X10 microemulsion(ME) in comparison with biphase systems.The yield of biphenyl in a Triton X10 ME system was found higher than that in the biphase system.The reactivities in different ME were also studied.The amount of sodium formate,base type,the amount of Pd/C,temperature on the conversion and selectivity of the coupling reaction were investigated.High conversion(up to 100%) and selectivity(up to 98%) of the reaction could be achieved when 10%(molar fraction) sodium fomate,2%(molar fraction) Pd/C,potassium carbonate and sodium hydroxide as base,80℃ reaction temperature and tetrabutylammo-nium chloride were used.Therefore,the microemulsion is an alternative reaction medium for Ullmann reaction.
2006, 23(10): 1145-1149
Abstract:
The magnesium oxide nanocrystallites were prepared by means of a sol-gel method with malic acid and magnesium nitrate as raw materials.Under different preparing conditions,the particle size can vary from 7 nm to 20 nm.The intermediate gel and final product were characterized by FI-IR,TG-DTA,XRD and TEM.The effects of the ratio of the raw materials,calcined temperature and time,the initial pH value and the amount of ethanol on the particle size and morphology of the sample were analyzed.The results show that the conditions of the molar ratio of Mg2+ to malic acid being 1:1.5,calcined temperature 500~700℃,calcined time 3 h,the initial pH value 3~7 and the volume ratio 1:4 are favorable for the formation of nanosized magnesium oxide.The UV-Vis Spectra show that the UV-shielding capacity of the nanosized magnesium oxide is better than that of normal magnesium oxide.
The magnesium oxide nanocrystallites were prepared by means of a sol-gel method with malic acid and magnesium nitrate as raw materials.Under different preparing conditions,the particle size can vary from 7 nm to 20 nm.The intermediate gel and final product were characterized by FI-IR,TG-DTA,XRD and TEM.The effects of the ratio of the raw materials,calcined temperature and time,the initial pH value and the amount of ethanol on the particle size and morphology of the sample were analyzed.The results show that the conditions of the molar ratio of Mg2+ to malic acid being 1:1.5,calcined temperature 500~700℃,calcined time 3 h,the initial pH value 3~7 and the volume ratio 1:4 are favorable for the formation of nanosized magnesium oxide.The UV-Vis Spectra show that the UV-shielding capacity of the nanosized magnesium oxide is better than that of normal magnesium oxide.
2006, 23(10): 1150-1155
Abstract:
Differential Scanning Calorimetry and Small Angle X-ray Diffractometry were used to characterize the phase transitions in lamellar liquid crystal systems containing water,alkyl polysorbates,sorbitan esters,stearyl alcohol and oil.The order-disorder transition temperatures of the gelled O/W and W/O globular onion lamellar phases LO1 and LO2 and planar gelled lamellar phase Lβ were measured as a function of system compositions.The results confirm that stearyl alcohol plays an important role in stabilizing the liquid crystalline phases,and the optimal stabilization of the globular(onion) phase is obtained at a surfactant to alcohol ratio of 1:1.Decreasing this ratio leads to the appearance of a planar phase coexisting with the onion phase and to a separate stearyl alcohol phase.The difference in transition temperature between the onion LO and planar Lβ phases suggests that these phases have different compositions.Decreasing the polarity of the oil extends the melting range of the Lβ phases,but also increases the degree of heterogeneity of liquid crystal phase.
Differential Scanning Calorimetry and Small Angle X-ray Diffractometry were used to characterize the phase transitions in lamellar liquid crystal systems containing water,alkyl polysorbates,sorbitan esters,stearyl alcohol and oil.The order-disorder transition temperatures of the gelled O/W and W/O globular onion lamellar phases LO1 and LO2 and planar gelled lamellar phase Lβ were measured as a function of system compositions.The results confirm that stearyl alcohol plays an important role in stabilizing the liquid crystalline phases,and the optimal stabilization of the globular(onion) phase is obtained at a surfactant to alcohol ratio of 1:1.Decreasing this ratio leads to the appearance of a planar phase coexisting with the onion phase and to a separate stearyl alcohol phase.The difference in transition temperature between the onion LO and planar Lβ phases suggests that these phases have different compositions.Decreasing the polarity of the oil extends the melting range of the Lβ phases,but also increases the degree of heterogeneity of liquid crystal phase.
2006, 23(10): 1156-1160
Abstract:
A series of 2-halogenopurine derivatives was synthesized from guanine through diazotization.All the products were characterized by 1H NMR,MS and elemental analysis.Fungicidal activities of all the compounds were tested.Good fungicidal activity was observed for 5a,5c,5g and 5h against Bacillus subtillis,5b and 5c against Aspergillus niger,and 5f against Cardida tropicals.Density functions of all the compounds were calculated using Gaussian 98,and the effect of different groups on the net charges of C(2) were discussed.
A series of 2-halogenopurine derivatives was synthesized from guanine through diazotization.All the products were characterized by 1H NMR,MS and elemental analysis.Fungicidal activities of all the compounds were tested.Good fungicidal activity was observed for 5a,5c,5g and 5h against Bacillus subtillis,5b and 5c against Aspergillus niger,and 5f against Cardida tropicals.Density functions of all the compounds were calculated using Gaussian 98,and the effect of different groups on the net charges of C(2) were discussed.
2006, 23(10): 1161-1165
Abstract:
Cuprous iodide semiconductor film consisted of a large amount of triangular sheets was prepared by means of electrochemical method.The electrochemical properties of the film were investigated in four 0.5 mol/L Na2SO4 solutions with pH values set at 0,2,4 and 7 via Electrochemical Impedance Spectroscopy(EIS).The result reveals that the pH value of electrolyte can affect the electrochemical properties.The lower the pH value is,the larger the reaction resistance is with the increase of pH,the surface scate density of the semiconductor was increased as the CuI lewis acid tends to absorb OH- ion its surface easily.The flat-band potential measured in 0.5 mol/L Na2SO4 solution with pH=0 is 0.002 3 V(vs.SCE).
Cuprous iodide semiconductor film consisted of a large amount of triangular sheets was prepared by means of electrochemical method.The electrochemical properties of the film were investigated in four 0.5 mol/L Na2SO4 solutions with pH values set at 0,2,4 and 7 via Electrochemical Impedance Spectroscopy(EIS).The result reveals that the pH value of electrolyte can affect the electrochemical properties.The lower the pH value is,the larger the reaction resistance is with the increase of pH,the surface scate density of the semiconductor was increased as the CuI lewis acid tends to absorb OH- ion its surface easily.The flat-band potential measured in 0.5 mol/L Na2SO4 solution with pH=0 is 0.002 3 V(vs.SCE).
2006, 23(10): 1166-1169
Abstract:
The alloy electrode of amorphous Ni-S-Mn electrodeposited on the surface of nickel net and used in water electrolysis was prepared and studied.The electrocatalytic activity of Ni-S-Mn electrode for hydrogen evolution reaction was evaluated by means of cathodic polarization curves and related electrochemical parameters.The results show that the overpotential of hydrogen evolution reaction is 180 mV and 80 mV less than Ni and Ni-S electrodes,respectively.This illustrates that the electrocatalytic activity of so-prepared Ni-S-Mn electrode is better than those of Ni and Ni-S electrodes.The potential scan with a small-amplitude triangular wave,SEM,TEM and XRD methods were applied to the analyses of the roughness,morphology and microstructure of the electrode surface.Finally,the role of element Mn was discussed in detail.
The alloy electrode of amorphous Ni-S-Mn electrodeposited on the surface of nickel net and used in water electrolysis was prepared and studied.The electrocatalytic activity of Ni-S-Mn electrode for hydrogen evolution reaction was evaluated by means of cathodic polarization curves and related electrochemical parameters.The results show that the overpotential of hydrogen evolution reaction is 180 mV and 80 mV less than Ni and Ni-S electrodes,respectively.This illustrates that the electrocatalytic activity of so-prepared Ni-S-Mn electrode is better than those of Ni and Ni-S electrodes.The potential scan with a small-amplitude triangular wave,SEM,TEM and XRD methods were applied to the analyses of the roughness,morphology and microstructure of the electrode surface.Finally,the role of element Mn was discussed in detail.
2006, 23(10): 1170-1172
Abstract:
The chiral resolution of malathion and fipronil enantiomers was performed by high-performance liquid chromatography with amylose tri-(S)-1-phenylethylcarbamate as chiral stationary phase.The mobile phase was n-hexane,with ethanol,1-propanol,2-propanol,1-butanol or 2-butanol used as polar modifiers.The flow rate was 1.0 mL/min and detecting wavelength was 230 nm.The best resolution factor for malathion was 0.85 with n-hexane/isopropanol as the mobile phase.The two enantiomers of fipronil could achieve baseline separation with the best resolution factor of 1.98.The optical rotations were determined by a circular dichroism detector.The elution order for malathion was +/- and that of fipronil was -/+ at 230 nm.The circular dichroism spectra for the enantiomers were also studied.
The chiral resolution of malathion and fipronil enantiomers was performed by high-performance liquid chromatography with amylose tri-(S)-1-phenylethylcarbamate as chiral stationary phase.The mobile phase was n-hexane,with ethanol,1-propanol,2-propanol,1-butanol or 2-butanol used as polar modifiers.The flow rate was 1.0 mL/min and detecting wavelength was 230 nm.The best resolution factor for malathion was 0.85 with n-hexane/isopropanol as the mobile phase.The two enantiomers of fipronil could achieve baseline separation with the best resolution factor of 1.98.The optical rotations were determined by a circular dichroism detector.The elution order for malathion was +/- and that of fipronil was -/+ at 230 nm.The circular dichroism spectra for the enantiomers were also studied.
2006, 23(10): 1173-1175
Abstract:
Effects of catalyst FeSO4 on molecular mass distribution,contents of carboxyl and carbonyl groups,and adhesive properties of the oxidized starches were investigated.The results show that the catalyst reduced the oxidation time of cassawa starch to 0.5 h,and increased the carboxyl and carbonyl contents in the oxidized starches by more than 105% and 12%,respectively.Gel Permeation Chromatography analysis showed that the molecular mass of the oxidized starch prepared with the catalyst was smaller,and the molecular mass distribution was more uniform than that of the starches oxidized without a catalyst.The solid content of the adhesive prepared by catalytically oxidized starch was as high as 28.9%.The adhesive strength of the adhesive was 57 N after drying for 15 min.
Effects of catalyst FeSO4 on molecular mass distribution,contents of carboxyl and carbonyl groups,and adhesive properties of the oxidized starches were investigated.The results show that the catalyst reduced the oxidation time of cassawa starch to 0.5 h,and increased the carboxyl and carbonyl contents in the oxidized starches by more than 105% and 12%,respectively.Gel Permeation Chromatography analysis showed that the molecular mass of the oxidized starch prepared with the catalyst was smaller,and the molecular mass distribution was more uniform than that of the starches oxidized without a catalyst.The solid content of the adhesive prepared by catalytically oxidized starch was as high as 28.9%.The adhesive strength of the adhesive was 57 N after drying for 15 min.
2006, 23(10): 1176-1178
Abstract:
Monolauryl citrate was synthesized by regioselective esterification.Reaction of citric acid with paraformaldehyde gave anhydromethylene citric acid(Ⅰ) with a yield of 63%;the reaction of compound(Ⅰ) with acetic anhydride gave the corresponding anhydride(Ⅱ) with a yield of 87%;the esterification of compound(Ⅱ) with lauryl alcohol gave anhydrocitric acid monoester(Ⅲ) with a yield of 76%.Refluxing(Ⅲ) with 1 equivalent of base in aqueous dioxane,the monolauryl citrate was obtained with a yield of 83%.All the compounds were characterized by means of 1H NMR,IR and Elemental Analysis.
Monolauryl citrate was synthesized by regioselective esterification.Reaction of citric acid with paraformaldehyde gave anhydromethylene citric acid(Ⅰ) with a yield of 63%;the reaction of compound(Ⅰ) with acetic anhydride gave the corresponding anhydride(Ⅱ) with a yield of 87%;the esterification of compound(Ⅱ) with lauryl alcohol gave anhydrocitric acid monoester(Ⅲ) with a yield of 76%.Refluxing(Ⅲ) with 1 equivalent of base in aqueous dioxane,the monolauryl citrate was obtained with a yield of 83%.All the compounds were characterized by means of 1H NMR,IR and Elemental Analysis.
2006, 23(10): 1179-1181
Abstract:
In an acetic acid-sodium acetate buffer medium,trace amounts of copper has sensitive catalytic activity toward the reduction of calcon with ascorbic acid in the presence of active agent O-phenanthroline.The optimum condition and kinetic parameter of the reaction were studied and a new method was established for the determination of trace amounts of copper.The detection limit in this method is 1.54×10-10 g/mL.The linear range is between 0~1.1×10-7 g/mL.This method was applied to the determination of copper in Mongolian medicine and hair sample with satisfactory results.
In an acetic acid-sodium acetate buffer medium,trace amounts of copper has sensitive catalytic activity toward the reduction of calcon with ascorbic acid in the presence of active agent O-phenanthroline.The optimum condition and kinetic parameter of the reaction were studied and a new method was established for the determination of trace amounts of copper.The detection limit in this method is 1.54×10-10 g/mL.The linear range is between 0~1.1×10-7 g/mL.This method was applied to the determination of copper in Mongolian medicine and hair sample with satisfactory results.
2006, 23(10): 1182-1184
Abstract:
The process of reducing and dissolving LiCoO2 in the lithium-ion battery by Na2S2O3 in the presence of H2SO4 was studied.It had high reaction rate and LiCoO2 dissolved completely with no contamination.The solubility rate of LiCoO2 was 99.5%.The optimal process conditions are that the concentration of H+ is 3.5 mol/L,the concentration of Na2S2O3 is 0.25 mol/L,reaction temperature is 90℃,reaction time is 2.3 h.Fe and Al in the system were removed by precipitation at pH≈5.Co(OH)2 was obtained by preci-pitation at pH=9.5~10,it was then purified by reprecipitation.Co3O4 was obtained by calcining Co(OH)2 at 500℃ for 2 h,the purity of which was 99.3%.The recovery rate of Co was 97%.Li2CO3 was obtained by adding Na2CO3 to the mother liquor,the purity of which was 97.8%.The one-time recovery for Li was 73%.The mother liquor can be reused after being cooled to below 10℃ and Na2SO4·10H2O is recovered.
The process of reducing and dissolving LiCoO2 in the lithium-ion battery by Na2S2O3 in the presence of H2SO4 was studied.It had high reaction rate and LiCoO2 dissolved completely with no contamination.The solubility rate of LiCoO2 was 99.5%.The optimal process conditions are that the concentration of H+ is 3.5 mol/L,the concentration of Na2S2O3 is 0.25 mol/L,reaction temperature is 90℃,reaction time is 2.3 h.Fe and Al in the system were removed by precipitation at pH≈5.Co(OH)2 was obtained by preci-pitation at pH=9.5~10,it was then purified by reprecipitation.Co3O4 was obtained by calcining Co(OH)2 at 500℃ for 2 h,the purity of which was 99.3%.The recovery rate of Co was 97%.Li2CO3 was obtained by adding Na2CO3 to the mother liquor,the purity of which was 97.8%.The one-time recovery for Li was 73%.The mother liquor can be reused after being cooled to below 10℃ and Na2SO4·10H2O is recovered.
