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1998 Volume 9 Issue 12
1998, 9(12): 1073-1074
Abstract:
N-arylsulfonyimines were reduced easily to the corresponding N-arylsulfonylamines with potassium selenated borohydride (KBH2Se3) under reflux in formamide.
N-arylsulfonyimines were reduced easily to the corresponding N-arylsulfonylamines with potassium selenated borohydride (KBH2Se3) under reflux in formamide.
1998, 9(12): 1075-1078
Abstract:
Phosphopeptides were synthesized with bis-alkyloxy-N,N-dialkylphosphoramidite followed by oxidation. Many hydroxyl groups in oligopeptides can be O-phosphorylated in one step.
Phosphopeptides were synthesized with bis-alkyloxy-N,N-dialkylphosphoramidite followed by oxidation. Many hydroxyl groups in oligopeptides can be O-phosphorylated in one step.
1998, 9(12): 1079-1080
Abstract:
The first stereoselective total synthesis of 3 (R)-panaxynol 1 has been achieved by utilizing the Cadiot-Chodkiczwicz reaction, through coupling of 3 (R)-(t-butyldiphenylsilyloxy)-l-penten-4-yne with l-bromo-alkyne compound.
The first stereoselective total synthesis of 3 (R)-panaxynol 1 has been achieved by utilizing the Cadiot-Chodkiczwicz reaction, through coupling of 3 (R)-(t-butyldiphenylsilyloxy)-l-penten-4-yne with l-bromo-alkyne compound.
1998, 9(12): 1081-1084
Abstract:
Correlation between the helical structure and optical activity of two derivatives of R-(+)-1,1'-binaphthyl-2,2'-diol was derived from a study of their optical rotations, CD curves and X-ray crystal structures.
Correlation between the helical structure and optical activity of two derivatives of R-(+)-1,1'-binaphthyl-2,2'-diol was derived from a study of their optical rotations, CD curves and X-ray crystal structures.
1998, 9(12): 1085-1086
Abstract:
The inclusion complex of C(x) with p-tert-butyl calix [8] arene tetraphenyl ether was prepared. The stoichiometry and association constant Kass of this inclusion complex were determined.
The inclusion complex of C(x) with p-tert-butyl calix [8] arene tetraphenyl ether was prepared. The stoichiometry and association constant Kass of this inclusion complex were determined.
1998, 9(12): 1087-1090
Abstract:
The semiempirical method AM1 was used to calculate △HOF values of perylenequinone (PQ), and △HOF was used as a theoretical parameter to predict the scavenging ability of PQ hydroxyls. Owing to strong intramolecular hydrogen bonds and the electron-attracting property of the keto-function, hydroxyls of PQ were so weak in scavenging free radicals that the its effect was negligible in photodynamic therapy. However, when PQ was substituted with strong electron-donating groups, its scavenging activity was enhanced markedly.
The semiempirical method AM1 was used to calculate △HOF values of perylenequinone (PQ), and △HOF was used as a theoretical parameter to predict the scavenging ability of PQ hydroxyls. Owing to strong intramolecular hydrogen bonds and the electron-attracting property of the keto-function, hydroxyls of PQ were so weak in scavenging free radicals that the its effect was negligible in photodynamic therapy. However, when PQ was substituted with strong electron-donating groups, its scavenging activity was enhanced markedly.
1998, 9(12): 1091-1092
Abstract:
The suppression of diorganogermanium compounds on the Mai Hard reaction of histidine (His) and glycine (Gly) with glucose has been determined by fluorescence spectrum under physiological conditions. The title compounds show inhibition for the fluorescence intensity (FI) of glycosylated amino acids stronger than Ge-132.
The suppression of diorganogermanium compounds on the Mai Hard reaction of histidine (His) and glycine (Gly) with glucose has been determined by fluorescence spectrum under physiological conditions. The title compounds show inhibition for the fluorescence intensity (FI) of glycosylated amino acids stronger than Ge-132.
1998, 9(12): 1093-1094
Abstract:
A new trinortriterpenoid, 1-epibrachycarpone, was isolated from the aerial parts of Cleome chrysantha. Its structure was elucidated by spectral and X-ray crystallographic studies.
A new trinortriterpenoid, 1-epibrachycarpone, was isolated from the aerial parts of Cleome chrysantha. Its structure was elucidated by spectral and X-ray crystallographic studies.
1998, 9(12): 1095-1096
Abstract:
Eight compounds were isolated from the ethanolic extracts of Lysimachia capillipes Hemsl. They were identified as capilliplactone 1,capillipnin 2,β-daucosterol 3,succinic acid 4, quercetin 5, 3',4',5,5',7-pentahydroxyflavone 6,quercetin-3-O-β-D-glucopyranoside 7 and kaempferol 8 on the basis of chemical and spectral methods. Among them, 1 and 2 were new, their structures were established as all-cis-5-deoxy-pentonic acid-y-lactone and 1,2,4,5-tetrahydroxy-3-n-pentyIbenzen-2,4-di-0-β-D-glucopyranoside through their spectral data (1HNMR, 13CNMR, DEPT, 1H-1H COSY, H1-13C COSY, HMBC etc).
Eight compounds were isolated from the ethanolic extracts of Lysimachia capillipes Hemsl. They were identified as capilliplactone 1,capillipnin 2,β-daucosterol 3,succinic acid 4, quercetin 5, 3',4',5,5',7-pentahydroxyflavone 6,quercetin-3-O-β-D-glucopyranoside 7 and kaempferol 8 on the basis of chemical and spectral methods. Among them, 1 and 2 were new, their structures were established as all-cis-5-deoxy-pentonic acid-y-lactone and 1,2,4,5-tetrahydroxy-3-n-pentyIbenzen-2,4-di-0-β-D-glucopyranoside through their spectral data (1HNMR, 13CNMR, DEPT, 1H-1H COSY, H1-13C COSY, HMBC etc).
1998, 9(12): 1097-1100
Abstract:
Two new sesquiterpenes:beishulenolide A 1 and peroxiatractylenolide Ⅲ 2 were isolated from Atractylodes macrocepkala Koids (compositae).Their structures were elucidated on the basis of spectral evidence, especially 2D-NMR methods and chemical conversion.
Two new sesquiterpenes:beishulenolide A 1 and peroxiatractylenolide Ⅲ 2 were isolated from Atractylodes macrocepkala Koids (compositae).Their structures were elucidated on the basis of spectral evidence, especially 2D-NMR methods and chemical conversion.
1998, 9(12): 1101-1104
Abstract:
A new taxane diterpenoid, named 7-deacetoxy taxinine J, together with ten known compounds were isolated from the needles of Taxus×media Hicksii. The structures of all compounds were elucidated and identified by spectroscopic methods. The structure of 7-deacetoxy taxinine J was further confirmed by X-ray crystallographic analysis. The structure of the known compound, taxinine E, was also revised.
A new taxane diterpenoid, named 7-deacetoxy taxinine J, together with ten known compounds were isolated from the needles of Taxus×media Hicksii. The structures of all compounds were elucidated and identified by spectroscopic methods. The structure of 7-deacetoxy taxinine J was further confirmed by X-ray crystallographic analysis. The structure of the known compound, taxinine E, was also revised.
1998, 9(12): 1105-1108
Abstract:
A rapid and sensitive 1.5 order adsorptive stripping voltammetric method for determination of trace mitoxantrone (MXT) is described. The accumulation behavior of MXT on a mercury film microelectrode was studied and the possibility of carrying out 1.5 order differential adsorptive stripping analysis using mercury-coated carbon fiber microelectrode was demonstrated. Optimal conditions for 1.5 order differential voltammetry monitoring are described. The stripping peak current is linearly proportional to the concentration of MAT in the range of 1.0×10-6mol/L-1.0×10-9 and detection limit is 1.5×10-10mol/L. The relative standard deviation (RSD) is 3.0% at 5.0×10-1 (n=8). MXT can be determined directly in biological samples at physiological levels without any separation procedure.
A rapid and sensitive 1.5 order adsorptive stripping voltammetric method for determination of trace mitoxantrone (MXT) is described. The accumulation behavior of MXT on a mercury film microelectrode was studied and the possibility of carrying out 1.5 order differential adsorptive stripping analysis using mercury-coated carbon fiber microelectrode was demonstrated. Optimal conditions for 1.5 order differential voltammetry monitoring are described. The stripping peak current is linearly proportional to the concentration of MAT in the range of 1.0×10-6mol/L-1.0×10-9 and detection limit is 1.5×10-10mol/L. The relative standard deviation (RSD) is 3.0% at 5.0×10-1 (n=8). MXT can be determined directly in biological samples at physiological levels without any separation procedure.
1998, 9(12): 1109-1112
Abstract:
A novel chemically-modified electrode containing 1:12 phosphomolybdic anions was achieved on the surface of platinum electrode by the sol-gel technique. The electrode exhibits a high catalytic activity towards the electroreduction of BrO3- anions.
A novel chemically-modified electrode containing 1:12 phosphomolybdic anions was achieved on the surface of platinum electrode by the sol-gel technique. The electrode exhibits a high catalytic activity towards the electroreduction of BrO3- anions.
1998, 9(12): 1113-1114
Abstract:
A novel low temperature phase K4InTi4O11 (OH)·5H20 was prepared by the hydrothermal method. The product was characterized by XRD, SEM, TG, DTA and ICP. The results indicated that the product crystallizes in a cubic system with a cell parameter a=0.7868 nm. Moreover, it ecomposes to an amorphous phase after calcining at 340℃.
A novel low temperature phase K4InTi4O11 (OH)·5H20 was prepared by the hydrothermal method. The product was characterized by XRD, SEM, TG, DTA and ICP. The results indicated that the product crystallizes in a cubic system with a cell parameter a=0.7868 nm. Moreover, it ecomposes to an amorphous phase after calcining at 340℃.
1998, 9(12): 1115-1118
Abstract:
Self-assembly of octadecyl mercaptan on gold was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Results of CV experiments show that there are no structural defects exposed directly to the redox couple in solution, but EIS experiments indicate that collapsed sites exist in the monolayer. A method to estimate the degree of disorder in the Au/thiol monolayer surface is proposed by using admittance plane plot.
Self-assembly of octadecyl mercaptan on gold was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Results of CV experiments show that there are no structural defects exposed directly to the redox couple in solution, but EIS experiments indicate that collapsed sites exist in the monolayer. A method to estimate the degree of disorder in the Au/thiol monolayer surface is proposed by using admittance plane plot.
1998, 9(12): 1119-1122
Abstract:
The aggregation kinetics of basic yttrium carbonate particles in aqueous solution have been studied using dynamic light-scattering techniques. In 1.00 mol/l NaCl solution fast diffusion-limited aggregation behavior was observed with an increase in aggregate size over time described by a power law. The aggregates are characterized by a fractal dimension D=1.82. Smoluchowski and fractal theories were used to characterize the aggregation mechanism and to obtain the aggregation rate constant.
The aggregation kinetics of basic yttrium carbonate particles in aqueous solution have been studied using dynamic light-scattering techniques. In 1.00 mol/l NaCl solution fast diffusion-limited aggregation behavior was observed with an increase in aggregate size over time described by a power law. The aggregates are characterized by a fractal dimension D=1.82. Smoluchowski and fractal theories were used to characterize the aggregation mechanism and to obtain the aggregation rate constant.
1998, 9(12): 1123-1124
Abstract:
The determination of the second dissociation constant of carbonic acid in 5, 15 and 25 mass % ethanol-water mixed solvents has been made by emf method at 278.15 to 318.15K.The solute-solvent interaction was discussed.
The determination of the second dissociation constant of carbonic acid in 5, 15 and 25 mass % ethanol-water mixed solvents has been made by emf method at 278.15 to 318.15K.The solute-solvent interaction was discussed.
1998, 9(12): 1125-1128
Abstract:
Iron Mercury Tetrathiocyanate (FeHg(SCN)4) has been synthesized and its structure has been determined. It belongs to the tetragonal system, 14 space group. The Hg-S-C≡N-Fe bridge leads to the formation of an infinite three dimensional network. Irradiated by a 1.064 nm Nd:YAG laser beam, FeHg (SCN)4 showed a 0.532 nm second harmonic intensity which is 0.6 times as that of organic nonlinear optical crystal urea.
Iron Mercury Tetrathiocyanate (FeHg(SCN)4) has been synthesized and its structure has been determined. It belongs to the tetragonal system, 14 space group. The Hg-S-C≡N-Fe bridge leads to the formation of an infinite three dimensional network. Irradiated by a 1.064 nm Nd:YAG laser beam, FeHg (SCN)4 showed a 0.532 nm second harmonic intensity which is 0.6 times as that of organic nonlinear optical crystal urea.
1998, 9(12): 1129-1132
Abstract:
A process for in situ synthesis of terbium complex with salicylic acid by a two-step sol-gel method in silica matrix has been proposed. The luminescence properties of the silica gels codoped with terbium and salicylic acid have also been discussed with respect to that of the gel doped with terbium and that of pure terbium complex with salicylic acid.
A process for in situ synthesis of terbium complex with salicylic acid by a two-step sol-gel method in silica matrix has been proposed. The luminescence properties of the silica gels codoped with terbium and salicylic acid have also been discussed with respect to that of the gel doped with terbium and that of pure terbium complex with salicylic acid.
1998, 9(12): 1133-1136
Abstract:
The nature of bonding in the title compound has been studied by using CASSCF and FOCI techniques. The ground state of IrC has been found to be 2△ arising primarily from:..1б22б21π41δ33б2 configuration, which forms a triple bond between Ir and C atoms (one б; two π). The lowest quartet state is 4Φ state which has the configuration:..1б22б21π42δ13б1 and lies higher than the ground state by 1.25eV. The molecular constants of the ground state calculated at CASSCF level by using Morse's mode are:Re=1.6904Å, De=4.86eV, We=l139 cm-1, and B0=0.5219cm-1 comparable with the spectrum values (Re=1.6858Å, De=6.44 eV, We=1051cm-1 and B0=0.5251cm-1).
The nature of bonding in the title compound has been studied by using CASSCF and FOCI techniques. The ground state of IrC has been found to be 2△ arising primarily from:..1б22б21π41δ33б2 configuration, which forms a triple bond between Ir and C atoms (one б; two π). The lowest quartet state is 4Φ state which has the configuration:..1б22б21π42δ13б1 and lies higher than the ground state by 1.25eV. The molecular constants of the ground state calculated at CASSCF level by using Morse's mode are:Re=1.6904Å, De=4.86eV, We=l139 cm-1, and B0=0.5219cm-1 comparable with the spectrum values (Re=1.6858Å, De=6.44 eV, We=1051cm-1 and B0=0.5251cm-1).
1998, 9(12): 1137-1140
Abstract:
The fraction of 4-coordinated borons and motional narrowing of lithium ion for oxysulfide glasses in the Li2S-B203(-LiBr) systems are measured by the 11B and 7Li NMR technique. The structrural modifications resulted from the modifier Li2S and dopant LiBr components and their effects on ionic conduction are discussed.
The fraction of 4-coordinated borons and motional narrowing of lithium ion for oxysulfide glasses in the Li2S-B203(-LiBr) systems are measured by the 11B and 7Li NMR technique. The structrural modifications resulted from the modifier Li2S and dopant LiBr components and their effects on ionic conduction are discussed.
1998, 9(12): 1141-1144
Abstract:
The title complex was synthesized by dissolving tyrosine (tyr) in an aqueous solution of Nd (C104)3 at NpH5, and its crystal structure was determined by X-ray diffraction methods. The complex is a novel pentadecanuclear with the 15 Nd3+ ions connected by μ3-OH- ions. The tyrosine ligands are all in their anionic form, and each coordinates to the neodymium ions via the nitrogen atom of the amino group and the two carboxyl oxygen atoms. The molecule a barrel structure.
The title complex was synthesized by dissolving tyrosine (tyr) in an aqueous solution of Nd (C104)3 at NpH5, and its crystal structure was determined by X-ray diffraction methods. The complex is a novel pentadecanuclear with the 15 Nd3+ ions connected by μ3-OH- ions. The tyrosine ligands are all in their anionic form, and each coordinates to the neodymium ions via the nitrogen atom of the amino group and the two carboxyl oxygen atoms. The molecule a barrel structure.
