摘要:

AbstractNile Blue can strongly bind to DNA and its affinity for DNA has been investigated by spectroscopy and spectroelectrochemistry. At low DNA concentrations, Nile Blue can bind to DNA(per nucleotide phosphate) to form a 1:1 association complex with the binding constant of 4.7 × 104L/mol and the major binding model of Nile Blue to DNA is “electrostatic binding”. However, the major binding model changes into “intercalative binding” at high DNA concentrations. In order to confirm which part of Nile Blue intercalating into DNA, the inclusion action of β‐cydodextrin (β‐CD) has been used to study the interaction. Nile Blue can be included into the hydrophobic cavity of β‐CD to form an inclusion complex with a stability constant of 1.9 × 103L/mol. The experimental results indicate that the naphthalene ring part of Nile Blue is included into β‐CD's hydrophobic cavity and the inclusion complex decomposes at high DNA concentrations. It may be deduced reasonably that the naphthalene ring part of Nile Blue molecule intercalates

ISSN:1001-604X    

DOI:10.1002/cjoc.20020200112

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2002

数据来源: WILEY

摘要:

AbstractA novel polyacrylaminothiourea chelating fiber was synthesized simply and rapidly from nitrilon (an acrylonitrile‐based synthetic fiber), which was applied to preconcentrate and separate of trace amount of Au(III), Pt(IV), Pd(IV) and Ir (IV) ions from solution of samples. The analyzed ions can be quantitatively concentrated by the fiber up to a flow rate of 20.0 mL/min at pH2, and can also be desorbed with 15 mL of 4 mol/L HCl + 3% thiourea from the fiber column with recoveries of 96.5%‐100%. The chelating fiber can be reused for ten times, the recoveries of these ions are still over 92%, and hundred to thousand times of excess of Fe(III), Al(III), Ca(II), Mg(II), Ni(II), Mn(II), Cu(II), Zn(II), and Cd (II) cause no interference on the determination of the analyzed ions by inductively‐coupled plasma atomic emission spectrometry (ICP‐AES). The static saturation adsorption capacities of the fiber for the analytes are in the range of 1.15‐2.80 mmol/g. The relative standard deviations for the determination of 20.0 ng/mL each of Au(III), Pt(IV), Pd(IV) and Ir (IV) are in the range of 0.7%‐3.0%. The recoveries for test from standard additions to real solution samples are between 96% and 100%. The concentration of each ion in powder sample detected by the method is in good agreement with the cert

ISSN:1001-604X    

DOI:10.1002/cjoc.20020200113

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2002

数据来源: WILEY

摘要:

AbstractAn on‐line UV spectrometric method for the quantitative determination of methanol increment of methanol‐water in the mobile phase (i.e., of greater concentration than that of the mobile phase) by frontal analysis (FA) of insulin in reversed phase liquid chromatography (RPLC) was presented. When the methanol increment concentration ranged from 0.05% to 0.50%,V(CH3OH)/V(H2O), a set of elution curves could be obtained at 198 nm by a diode‐array detector in the presence of 47% methanol,V(CH3OH)/V(H2O) containing 0.03% hydrochloric add,V(CH3OH‐H2O)/V(HCl) in the mobile phase. The plateau height of the elution curves of the methanol increment was found to be proportional to the methanol increment in the mobile phase. The methanol increment could be determined on a quantitative basis. When the method was used to investigate the elution curve of insulin by FA in RPLC, a small plateau, being the methanol increment, was detected before the usual insulin plateau of each elution curve. In this case the methanol increment was found to vary with insulin concentration in the mobile phase. When that concentration was between 0.025 mg/mL and 0.30 mg/mL, the methanol increment could be determined in the range from 0.03% to 0.19% with a deviation of ± 0.02% and a relative deviation of ± 10%. A nuclear magnetic resonance spectrometer (NMR) was also employed to confirm the obtained result. A methodology with a very rigorous experimental procedure for obtaining results of such accuracy is also included. The presented result may be used to prove that a displacement process definitely occurs as insulin is adsorbed by the RPLC stationary p

ISSN:1001-604X    

DOI:10.1002/cjoc.20020200114

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2002

数据来源: WILEY

摘要:

AbstractCyanobenzaldehydes (m‐,o‐, p‐) were synthesized by oxidation of corresponding tolunitriles with molecular oxygen, catalyzed by cobalt acetate and sodium br

ISSN:1001-604X    

DOI:10.1002/cjoc.20020200115

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2002

数据来源: WILEY

摘要:

AbstractThe syntheses of three new optically active β‐mercaptoalcohols, (R)‐1,1‐diphenyl‐2‐mercapto‐3‐methyl‐1‐butanol, (R)‐1,1‐diphenyl‐2‐mercapto‐4‐methyl‐1‐pentanol, and (R)‐1,1‐diphenyl‐2‐mercapto‐l‐benzenepropanol from the corresponding amino adds are described. The enantiomeric excesses of these β‐mercaptoalcohols were deter

ISSN:1001-604X    

DOI:10.1002/cjoc.20020200116

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2002

数据来源: WILEY

摘要:

AbstractA series ofC2‐symmetrical chiral 2,5‐bis(4′‐alkyloxazolin‐2‐yl) thiophenes (thiobox) have been synthesized from thiophene‐2, 5‐dicarboxylic acid by sequential amidation with a chiral ethanolamine, conversion of hydroxyl to chloro group, and base‐promoted oxazoline ring formation. As demonstrated by ( ‐ )‐2, 5‐Ws[4′‐( S)‐isopropyloxazolin‐2′‐yl] thiophene, these thiobox systems exhibited remarkable chirality recognition of 1, 1′‐bi‐2‐naphthol giving rise to pronounced shifts in thelH NMR signals of the latter axial chiral compound

ISSN:1001-604X    

DOI:10.1002/cjoc.20020200117

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2002

数据来源: WILEY

摘要:

AbstractThe emission spectra of a series of naphthalene end‐labeled oligo‐oxyethylene (N‐Pn‐N) and their facilitated transport of cations across liquid membranes have been investigated. Alkali‐metal cations enhance or inhibit the intramolecular excimer formation of N‐Pn‐N remarkably, suggesting that the polyether chain of N‐Pn‐N in solution complexes with the cations, and the orientation of the terminal chromophores depends on the cation size and the length of the polyether chain. These compounds are able to act as carriers to facilitate transport of alkali‐metal cations through organic liquid membranes. The transport efficiencies are comparable with those of cyclic carriers such as crown ethers, and show rem

ISSN:1001-604X    

DOI:10.1002/cjoc.20020200118

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2002

数据来源: WILEY

摘要:

AbstractNew type of substituted 1H‐pyrazole‐4‐carboxamides were obtained by regioselective synthesis under the catalysis of different bases. The structures of the title compounds were confirmed by elemental analysis,1H NMR, IR, MS and X‐ray crystallography. Compounds 1 were transacylated into their corresponding amides 3 in the presence of sodium hydride. Preliminary bioassays indicated that some compounds showed fungicidal activities againstRhizoctonia solaniandSclerotinia scler

ISSN:1001-604X    

DOI:10.1002/cjoc.20020200119

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2002

数据来源: WILEY

摘要:

AbstractA series of homoallyl β',γ'‐unsaturated amines were synthesized via 1,2‐addition of α,β‐unsaturated imines with allylsamarium bromide in excellent yields under mild and neutral c

ISSN:1001-604X    

DOI:10.1002/cjoc.20020200120

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2002

数据来源: WILEY

摘要:

AbstractBiogenic silica with amazing diversity of nanostructure shells, fibers and granules in diatoms and sponges is radiated by proteins and polysaccharides and forms at ambient pressure and temperatures. Chemical synthetic methods, in contrast, have to rely on extreme pH and/or surfactants to induce the condensation of silica precursors into specific patterns. One kind of benign synthesis method through plant cell wall template‐directed ordered biosilica materials under ambient conditions is intriguing in this context. Organized silica materials in intercellular spaces of epidermal cells of tall fescue leaves were synthesized through molecular recognition between Si‐OH and polysaccharide‐OH or glycoprotein‐OH of main components of plant cell walls and cellular processing as well when Si(OEt)4was supplied rather than monosilicic acid. The biosynthesis of structural silica in tall fescue plant was correlated with the Si species applied, reflecting the slower condensation from tetraethoxysilane (TEOS) and thus providing greater opportunities for structural control by the underlying matrix of cell walls. The composition was estimated by energy dispersive X‐ray (EDX) spectra on a scanning electron microscope. All organized structures showed carbon, oxygen and silicon peaks, indicating that their formations differ from natural siliceou

ISSN:1001-604X    

DOI:10.1002/cjoc.20020200121

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2002

数据来源: WILEY