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1995 Volume 6 Issue 6
1995, 6(6): 455-456
Abstract:
Seven title compounds were synthesized by condensation of 4'-demethylepipodophyllotoxin with 4.5-diaryl-3-mercapto-1.2.4-triazoles in the presence of CF3COOH (TFA).
Seven title compounds were synthesized by condensation of 4'-demethylepipodophyllotoxin with 4.5-diaryl-3-mercapto-1.2.4-triazoles in the presence of CF3COOH (TFA).
1995, 6(6): 457-458
Abstract:
Asymmetric reduction of some α-diketones such as 1-phenyl-1, 2-propanedione and substituted benzils with fungus Geotrichum sp.G38 afforded corresponding optically active α-ketols in excellent chemical and optical yields.
Asymmetric reduction of some α-diketones such as 1-phenyl-1, 2-propanedione and substituted benzils with fungus Geotrichum sp.G38 afforded corresponding optically active α-ketols in excellent chemical and optical yields.
1995, 6(6): 459-462
Abstract:
A series of 5-substituted-2-chloro-6-methyl-4, 7-dioxobenzothiazole derivatives hare been synthesized by interaction of 2-chloro-6-methyl-4, 7-dioxobenzothiazole with the appropriate alkylamine and alkyl mercaptan.Their structures are identified by UV, IR, 1H-NMR and MS spectrum analysis.
A series of 5-substituted-2-chloro-6-methyl-4, 7-dioxobenzothiazole derivatives hare been synthesized by interaction of 2-chloro-6-methyl-4, 7-dioxobenzothiazole with the appropriate alkylamine and alkyl mercaptan.Their structures are identified by UV, IR, 1H-NMR and MS spectrum analysis.
1995, 6(6): 463-464
Abstract:
Caulimovirus contains a highly conserved, low molecular weight protein which has a zinc finger-like motif CysX2CysX4HisX4Cys in common with the animal retroviruses.The zinc finger-like peptide of caulimovirus (17 residues) was synthesized by solid phase method for structural study.Both standard HF treatment and "low-high HF" treatment were used to cleave the peptide from the resin.The peptide cleaved with "low-high" HF had higher purity and yield than that with standard HF cleavage.Circular dichroic spectroscopy indicates that the peptide exhibits a random coil conformation in the absence of zinc but appears to form an ordered structure in the presence of zinc.
Caulimovirus contains a highly conserved, low molecular weight protein which has a zinc finger-like motif CysX2CysX4HisX4Cys in common with the animal retroviruses.The zinc finger-like peptide of caulimovirus (17 residues) was synthesized by solid phase method for structural study.Both standard HF treatment and "low-high HF" treatment were used to cleave the peptide from the resin.The peptide cleaved with "low-high" HF had higher purity and yield than that with standard HF cleavage.Circular dichroic spectroscopy indicates that the peptide exhibits a random coil conformation in the absence of zinc but appears to form an ordered structure in the presence of zinc.
1995, 6(6): 465-466
Abstract:
Four analogs of the Schistosoma mansoni P28 antigenic peptide P141 were designed according to the similarity in the structure of the amino acid residues and Chou-Fasman's secondary structurally conformational parameters Pα, Pβ and Pt values, also according to the hydrophilicity of the amino acid residues.They were syntliesized by using Merrifield solid phase peptide synthesis method.ELISA experiments showed their antigenicity.
Four analogs of the Schistosoma mansoni P28 antigenic peptide P141 were designed according to the similarity in the structure of the amino acid residues and Chou-Fasman's secondary structurally conformational parameters Pα, Pβ and Pt values, also according to the hydrophilicity of the amino acid residues.They were syntliesized by using Merrifield solid phase peptide synthesis method.ELISA experiments showed their antigenicity.
1995, 6(6): 467-468
Abstract:
The dry Wittig reaction of stable ylides with aldehydes were performed within several minutes under microwave irradiation.Remarkable rate enhancements and dramatic reductions of reaction times have been observed.
The dry Wittig reaction of stable ylides with aldehydes were performed within several minutes under microwave irradiation.Remarkable rate enhancements and dramatic reductions of reaction times have been observed.
1995, 6(6): 469-472
Abstract:
The rates and yields of two Diels-Alder reactions, employing a series of different solvents as the energy-transfer medium under microwave irradiation (frequency, 2450 MHZ) and conventional refluxing at ambient pressure, have been compared The more polar the solvent used, the more increasing in yield was got by microwave irradiation.
The rates and yields of two Diels-Alder reactions, employing a series of different solvents as the energy-transfer medium under microwave irradiation (frequency, 2450 MHZ) and conventional refluxing at ambient pressure, have been compared The more polar the solvent used, the more increasing in yield was got by microwave irradiation.
1995, 6(6): 473-476
Abstract:
A new Annonaceous acetogenin, named uvarigranin(Ⅰ), was isolated from the ethanol extract of the roots of Uvaria grandiflora Roxb, together with the known isodesacetyluvaricin (Ⅱ).Their plane structures and relative configurations were established on the basis of NMR and MS spectroscopic methods.Compound I belongs to a mono-t trahydrofuran (THF) type acetogenin with an unusual acetoxy group at the adjacent carbon on the THF ring.
A new Annonaceous acetogenin, named uvarigranin(Ⅰ), was isolated from the ethanol extract of the roots of Uvaria grandiflora Roxb, together with the known isodesacetyluvaricin (Ⅱ).Their plane structures and relative configurations were established on the basis of NMR and MS spectroscopic methods.Compound I belongs to a mono-t trahydrofuran (THF) type acetogenin with an unusual acetoxy group at the adjacent carbon on the THF ring.
1995, 6(6): 477-478
Abstract:
A new isoflavone designated as eurycarpin A (Ⅰ)has been isolated from the root of Glycyrrhiza eurycarpa P.C.Li.Based on spectroscopic data, its structure was established as 7, 2', 4'-trihydroxy-3'(3, 3-dimethylallyl) isoflavone.
A new isoflavone designated as eurycarpin A (Ⅰ)has been isolated from the root of Glycyrrhiza eurycarpa P.C.Li.Based on spectroscopic data, its structure was established as 7, 2', 4'-trihydroxy-3'(3, 3-dimethylallyl) isoflavone.
1995, 6(6): 479-482
Abstract:
Two new taxane diterpenoids from Taxus yunnanensis were elucidated by spectroscopic techniques, one of which was identified as a unique taxane with 2, 20-oxo group.
Two new taxane diterpenoids from Taxus yunnanensis were elucidated by spectroscopic techniques, one of which was identified as a unique taxane with 2, 20-oxo group.
1995, 6(6): 483-486
Abstract:
Four new taxanes were isolated from the roots of Taxus yunnanensis.Among them, two were determined to contain isobutyrate group and propionyloxy group on C-14 respectively, and one was determined as the least oxygenated taxane.The structures were elucidated by spectroscopic means.
Four new taxanes were isolated from the roots of Taxus yunnanensis.Among them, two were determined to contain isobutyrate group and propionyloxy group on C-14 respectively, and one was determined as the least oxygenated taxane.The structures were elucidated by spectroscopic means.
1995, 6(6): 487-490
Abstract:
MINDO/3 method has been used to study the thermolyses of 1, 5-cyclooctadiene and 4-vinylcyclohexene.The results obtained show that the activation energies of the reta-determining steps are 197.936 and 225.534 kJ.mol-1, respectively.
MINDO/3 method has been used to study the thermolyses of 1, 5-cyclooctadiene and 4-vinylcyclohexene.The results obtained show that the activation energies of the reta-determining steps are 197.936 and 225.534 kJ.mol-1, respectively.
1995, 6(6): 491-494
Abstract:
On the basis of the improved self-exchange model of reorganization phenomenon and accurate potential functions from ab initio calculation at HFSCF 6-31G■ and DZP levels, a new calculation method was presented for the inner-sphere reorganization energy, values for diatomic molecular redox couples in gas phase electron transfer process have been calculated.Results agree well with the experimental data, and the effectiveness and importance of this method have been demonstrated for calculation of innersphere reorganization energy in gas phase electron transfer process.
On the basis of the improved self-exchange model of reorganization phenomenon and accurate potential functions from ab initio calculation at HFSCF 6-31G■ and DZP levels, a new calculation method was presented for the inner-sphere reorganization energy, values for diatomic molecular redox couples in gas phase electron transfer process have been calculated.Results agree well with the experimental data, and the effectiveness and importance of this method have been demonstrated for calculation of innersphere reorganization energy in gas phase electron transfer process.
1995, 6(6): 495-496
Abstract:
A new fluorometric method for the determination of sulfonamides is described, based on the formation of a fluorescent inclusion complex of carbonic anhydrase (CA) with dansylamide (DNSA).The fluorescence maximum emission of the complex is at 460nm with excitation at 280nm.Dissociation constants were determined for the CA-sulfonamide complexes.Limits of detection for DNSA, sulfanilamide(SAN) and ptoluenesulfonamide (PTSN) were 0.84, 19.5 and 6.1ng/ml, respectively.The recommended method was applied to the determination of sulfonamides in cow milk at ng/ml level.
A new fluorometric method for the determination of sulfonamides is described, based on the formation of a fluorescent inclusion complex of carbonic anhydrase (CA) with dansylamide (DNSA).The fluorescence maximum emission of the complex is at 460nm with excitation at 280nm.Dissociation constants were determined for the CA-sulfonamide complexes.Limits of detection for DNSA, sulfanilamide(SAN) and ptoluenesulfonamide (PTSN) were 0.84, 19.5 and 6.1ng/ml, respectively.The recommended method was applied to the determination of sulfonamides in cow milk at ng/ml level.
1995, 6(6): 497-500
Abstract:
A GC-MS method for the confirmation of benzthiazide is reported for the first time.This method is based on the main decomposed product of the methylated.derivative and provides a reliable detection of this drug.The detection limit of the method is 1.0ng with selected ion monitoring.
A GC-MS method for the confirmation of benzthiazide is reported for the first time.This method is based on the main decomposed product of the methylated.derivative and provides a reliable detection of this drug.The detection limit of the method is 1.0ng with selected ion monitoring.
1995, 6(6): 501-504
Abstract:
A nickel hexacyanoferrate modifled microband gold electrode, which can be prepared by cyclic voltammetry, exhibits excellent electrocatalytic activity for NADH oxidation with an overpotential ca.340mV lower than that at the bare electrode.Quantitative analysis of the electrocatalytic reaction based on rotating disk voltammetry gives a rate constantk of the order of 103 L·mol-1·s-1.
A nickel hexacyanoferrate modifled microband gold electrode, which can be prepared by cyclic voltammetry, exhibits excellent electrocatalytic activity for NADH oxidation with an overpotential ca.340mV lower than that at the bare electrode.Quantitative analysis of the electrocatalytic reaction based on rotating disk voltammetry gives a rate constantk of the order of 103 L·mol-1·s-1.
1995, 6(6): 505-508
Abstract:
The flow rate sensitivity of membrane-covered oxygen gas sensor has been tested experimentally.As the oxygen sensor, gas flowmeter, and air pump are arranged in six types of connective modes, the flow rate sensitivity of oxygen sensor is notably different.Preliminary results on the positional flow rate sensitivity of oxygen gas sensor are reported.
The flow rate sensitivity of membrane-covered oxygen gas sensor has been tested experimentally.As the oxygen sensor, gas flowmeter, and air pump are arranged in six types of connective modes, the flow rate sensitivity of oxygen sensor is notably different.Preliminary results on the positional flow rate sensitivity of oxygen gas sensor are reported.
1995, 6(6): 509-512
Abstract:
A vitamin B1 (VB1) ion-selective microelectrode based on nitrobenzene and 1, 2-dichloroethane/water interfaces at the tip of a dual-section micropipette was examined by using cyclic voltammetry, asymmetric sweep rate cyclic voltammetry and stripping voltammetry.Trace VB1 could be determined down to 4.6×10-6mol/L in aqueous sample solution, and some transfer data of VB1 were obtained.
A vitamin B1 (VB1) ion-selective microelectrode based on nitrobenzene and 1, 2-dichloroethane/water interfaces at the tip of a dual-section micropipette was examined by using cyclic voltammetry, asymmetric sweep rate cyclic voltammetry and stripping voltammetry.Trace VB1 could be determined down to 4.6×10-6mol/L in aqueous sample solution, and some transfer data of VB1 were obtained.
1995, 6(6): 513-516
Abstract:
The regulative function of La3+on the self-assembled glutathione(GSH) monolayer Au electrode for the ion-gate response was studied in aqueous Fe(CN)6 solution at pH 5.6 and compared with the function of Ca2+.It was found that La3+ has stronger effect than Ca2+.
The regulative function of La3+on the self-assembled glutathione(GSH) monolayer Au electrode for the ion-gate response was studied in aqueous Fe(CN)6 solution at pH 5.6 and compared with the function of Ca2+.It was found that La3+ has stronger effect than Ca2+.
1995, 6(6): 517-518
Abstract:
The catalytic behaviours of SiO2-supported HRh (DPPE)2 catalyst for CO hydrogenation and hydroformylation of propene were reported.
The catalytic behaviours of SiO2-supported HRh (DPPE)2 catalyst for CO hydrogenation and hydroformylation of propene were reported.
1995, 6(6): 519-520
Abstract:
The (dppe)Rh (μ-CO)2M (CO)3 (M=Cr, Mo, W) heterobinuclear metal carbonyl compounds were synthesized and characterized by IR and 1NMR.Their catalytic activities for CO hydrogenation were determined.
The (dppe)Rh (μ-CO)2M (CO)3 (M=Cr, Mo, W) heterobinuclear metal carbonyl compounds were synthesized and characterized by IR and 1NMR.Their catalytic activities for CO hydrogenation were determined.
1995, 6(6): 521-522
Abstract:
Fe2O3/ZrO2 catalysts were used for CO hydrogenation.For 7%wt Fe2O3/ZrO2, the F-T products distribution significantly deviated from the Schulz-Flory rule and selectivity to light olefins was enhanced.
Fe2O3/ZrO2 catalysts were used for CO hydrogenation.For 7%wt Fe2O3/ZrO2, the F-T products distribution significantly deviated from the Schulz-Flory rule and selectivity to light olefins was enhanced.
1995, 6(6): 523-526
Abstract:
We report here the photovoltaic behavior of a series of substituted ethenyl aniline derivatives containing donor and acceptor groups.This work indicates that the photovoltaic response is closely correlated with the substituents.The molecular structure/photovoltaic response relationship is presented and discussed in terms of the charge separation in an intramolecular charge transfer compound.
We report here the photovoltaic behavior of a series of substituted ethenyl aniline derivatives containing donor and acceptor groups.This work indicates that the photovoltaic response is closely correlated with the substituents.The molecular structure/photovoltaic response relationship is presented and discussed in terms of the charge separation in an intramolecular charge transfer compound.
1995, 6(6): 527-530
Abstract:
29Si and 7Li NMR have been used to study the sol-gel process.It has been found that the doping components (such as TlNO3, LiNO2, and Cd(NO3)2) could promote the hydrolysis and condensation reactions and their ratio, thus they could influence the gelation time.The lithium species has been demonstrated to remain as free hydration ions during the whole sol-gel process and not to participate in forming the inorganic network.
29Si and 7Li NMR have been used to study the sol-gel process.It has been found that the doping components (such as TlNO3, LiNO2, and Cd(NO3)2) could promote the hydrolysis and condensation reactions and their ratio, thus they could influence the gelation time.The lithium species has been demonstrated to remain as free hydration ions during the whole sol-gel process and not to participate in forming the inorganic network.
1995, 6(6): 531-532
Abstract:
The complex formation equilibria of M2+ ions (M=Co, Ni, Cu, Zn) with 6-aminopenicillanic acid (6-APA) have been studied through potentiometric titrations.The results show that all of metal ions form 1:1 complexes (M(APA)+, M(APA) (OH)) with 6-APA in solution.Formation constants of the complexes were determined at 40℃ in aqueous solution having a fixed ionic strength (0.1M NaClO4) and correlated with the second-order rate constants for metal-ion catalysed hydrolysis of penicillin.
The complex formation equilibria of M2+ ions (M=Co, Ni, Cu, Zn) with 6-aminopenicillanic acid (6-APA) have been studied through potentiometric titrations.The results show that all of metal ions form 1:1 complexes (M(APA)+, M(APA) (OH)) with 6-APA in solution.Formation constants of the complexes were determined at 40℃ in aqueous solution having a fixed ionic strength (0.1M NaClO4) and correlated with the second-order rate constants for metal-ion catalysed hydrolysis of penicillin.
1995, 6(6): 533-536
Abstract:
Three new heterotrinuclear complexes have been synthesized and characterized, namely {[Gd(L)2]2 [Cu (pbaOH)]} (ClO4)4, where pbaOH denotes 2-hydroxy-1, 3-propylenebis(oxamato), L stands for 1, 10-phenanthroline (phen), 5-nitro-1, 10-phenan-throline (NO2-phen) or 2, 2'-bipyridyl (bpy).The temperature dependence of the magnetic susceptibility of {[Gd(phen)2 (ClO4)2]2 [Cu (pbaOH)]} (ClO4)2 has been studied in the 4-300K range, giving the exchange integral J=6.69 cm-1.This indicates a weak ferromagnetic interaction between the copper(Ⅱ) and gadolinium (Ⅲ) ions.
Three new heterotrinuclear complexes have been synthesized and characterized, namely {[Gd(L)2]2 [Cu (pbaOH)]} (ClO4)4, where pbaOH denotes 2-hydroxy-1, 3-propylenebis(oxamato), L stands for 1, 10-phenanthroline (phen), 5-nitro-1, 10-phenan-throline (NO2-phen) or 2, 2'-bipyridyl (bpy).The temperature dependence of the magnetic susceptibility of {[Gd(phen)2 (ClO4)2]2 [Cu (pbaOH)]} (ClO4)2 has been studied in the 4-300K range, giving the exchange integral J=6.69 cm-1.This indicates a weak ferromagnetic interaction between the copper(Ⅱ) and gadolinium (Ⅲ) ions.
1995, 6(6): 537-538
Abstract:
A new ligand, formylferrocene 5-norbornene-2-carboxylic hydrazonc (HL), and its transition metal (Co2+, Ni2+ and Hg2+) complexes have been synthesized and characterized by elemental analyses, i.r.and 1Hn.m.r.spectra.The single crystal of nickel complex has been obtained and determined by X-ray diffraction method.
A new ligand, formylferrocene 5-norbornene-2-carboxylic hydrazonc (HL), and its transition metal (Co2+, Ni2+ and Hg2+) complexes have been synthesized and characterized by elemental analyses, i.r.and 1Hn.m.r.spectra.The single crystal of nickel complex has been obtained and determined by X-ray diffraction method.
1995, 6(6): 539-542
Abstract:
In this letter the calculated results for the title molecules and ion by DV-Xα method are given.The results show that the insertion of CO into Zr-H bond takes place by forming a σ dative bond, and CO into Zr-C bond by forming a feedback π bond, but that of CO into Zr-O bond easily gives rise to the break of the structure.Also, the Cσ atom of Cp2Zr(OCH)2 can not be hydrogenated except for the broken O-C bond.Perhaps these are the basis of ZrO2 catalysis producing light olefin.
In this letter the calculated results for the title molecules and ion by DV-Xα method are given.The results show that the insertion of CO into Zr-H bond takes place by forming a σ dative bond, and CO into Zr-C bond by forming a feedback π bond, but that of CO into Zr-O bond easily gives rise to the break of the structure.Also, the Cσ atom of Cp2Zr(OCH)2 can not be hydrogenated except for the broken O-C bond.Perhaps these are the basis of ZrO2 catalysis producing light olefin.
1995, 6(6): 543-544
Abstract:
The pervaporation behaviours of aqueous ethanol mixtures through the poly (ethylene oxide) (PEO)/chitosan (CS) blend membrane have been investigated.The results show that both CS and PBO/CS membranes preferentially permeate ethanol at lower ethanol concentration in feed, and the selectivity of chitosan membrane toward alcohol can be greatly improved by introducing water-soluble polymer PBO into chitosan.
The pervaporation behaviours of aqueous ethanol mixtures through the poly (ethylene oxide) (PEO)/chitosan (CS) blend membrane have been investigated.The results show that both CS and PBO/CS membranes preferentially permeate ethanol at lower ethanol concentration in feed, and the selectivity of chitosan membrane toward alcohol can be greatly improved by introducing water-soluble polymer PBO into chitosan.
1995, 6(6): 545-548
Abstract:
Isotopic ratio measurement was carried out for dysprosium, using the absolute isotopic ratio of europium of our laboratory standard, R151/153=0.9161(15)on 2σ basis, to calibrate the mass spectrometer, yielding the atomic weight of dysprosium, Ar (Dy)=162.500(2) on 2σ basis.In addition, a summary is given for the three rare earth elements examined in this series of atomic weight determinations.
Isotopic ratio measurement was carried out for dysprosium, using the absolute isotopic ratio of europium of our laboratory standard, R151/153=0.9161(15)on 2σ basis, to calibrate the mass spectrometer, yielding the atomic weight of dysprosium, Ar (Dy)=162.500(2) on 2σ basis.In addition, a summary is given for the three rare earth elements examined in this series of atomic weight determinations.
