摘要:

AbstractA porphyrin‐phthalocyanine heterodimer linked by piperazine has been synthesized and characterized by spectroscopic methods. UV‐visible absorption spectra indicated the presence of weak intramolecular interaction between the two chromophores. Selective excitation of the porphyrin moiety leads to energy transfer process to the phthalocyanine subunit. Furthermore, on the bases of the solvent‐dependent fluorescence data, a competing electron transfer reaction is shown to occur in this heterodimer. The efficiency of both photophysical processes depends strongly on solvent polarity and is related to the separation distance of the two chromophores and their relative orientation. The value of ΔG 0ETobtained using the Rehm‐Weller equation clearly indicates that the heterodimer exists preferably in the “boat form” upon excitation in good agreement with the experimental results of co‐occurence of energy and electron transfer process observed for

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160202

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

年代:1998

数据来源: WILEY

摘要:

AbstractInfluence of norbornadiene and its derivatives on the photoluminescence (PL) of quantum‐confined cadmium sulfide clusters (Q‐CdS) prepared in reverse micelles wm investigated. It was found that norbornadiene‐2,3‐dicarboxylic acid (3) and its monopotassium salt (4) quenched PL intensity by 77% and 62%, respectively, whereas its dipotassium salt (a), norbornadiene (1) and norbornadiene‐2,3‐dimethylcarboxylate (2) had no effect on PL intensity. The formation constants for adducts formed between defect sites at the surface of Q‐CdS clusters and 3 or 4 were also determined. PL quenching effect was attributed to the presence of ionizable proton which is considered to be able to trap photogenerated electrons and remove them from possible decay process. Measurements of the PL decay by single photon counting technique also supported these steady‐sta

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160203

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

年代:1998

数据来源: WILEY

摘要:

AbstractSix novel oxovanadium(IV) binuclear complexes have been synthesized and characterized, namely, [(VO)2(CA)L2]SO4[L denotes 5‐methyl‐1,10‐phenanthroline (Me‐phen); 2,9‐dimethyl‐1,10‐phenanthroline (Me2‐phen); 5‐chloro‐1,10‐phenanthroline (Cl‐phen); diaminoethane (en); 1,3‐diaminopropane (pn) and 1,2‐diaminopropane (ap) respectively.], where CA represents the dianion of chloranilic acid. Based on elemental analyses, molar conductivity and room temperature magnetic moment measurements, IR and electronic spectral studies, it is proposed that there complexes have CA‐bridged structures and consist of two vanadium(IV) ions in a square‐pyramidal environment. The complexes [(VO)2(CA)(Me‐phen)2]SO4(1) and [(VO)2(CA)(Me2‐phen)2]SO4(2) were characterized by variable temperature magnetic susceptibility measurements (4∼300 K) and the observed data were fitted to the modified Bleaney‐Bowers equation by the least‐squares method, giving the exchange integralJ=‐15.8 cm−1for 1 andJ=‐10.6 cm−lfor 2. This result indicates that there is a weak antiferromagnetic spin‐exchange intera

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160204

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

年代:1998

数据来源: WILEY

摘要:

AbstractA set of novel graph‐theoretical parameters, called the atomic distance‐edge (ADE) vector, was developed. Baaed on the connecting C‐C bond number between central carbon atom and the other ones, various carbon atoms of alkanes were classified as four types, i.e., type 1, 2, 3 and 4 for primary, secondary, ternary and quaternary carbon, respectively; and then four regression equations were obtained to link carbon‐13 chemical shift (CS) of each type of atoms. Furthermore, these regression models were used to predict the carbon‐13 nuclear magnetic resonance spectra of alkanes and it was found that the estimated CS were in agreement with the experimenta

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160205

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

年代:1998

数据来源: WILEY

摘要:

AbstractThe transfer of lanthanum ion facilitated by diantipyrylmethane (DAM) across the water/nitrobenzene (w/nb) interface and the adsorption of emulsifier OP at the w/nb interface has been studied by the cyclic voltammetry. The mechanism of the charge transfer reactions is discussed. It has been concluded that the transfer of rare earth metal ion (La3+) facilitated by neutral ionophore (DAM) at the w/nb interface is E mechanism and the nonionic surfactant (emulsifier OP) can participate in the charge transfer process M an ionophore, charge transfer catalyst and inhibitor.

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160206

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

年代:1998

数据来源: WILEY

摘要:

AbstractA computer‐assisted method is described for optimization of multi‐component, mobile phase selection for separation of five phosphoamidothioate enantiomers with a series of silica and chiral columns in normal phase HPLC. The method is based on the triangular solvent selection concept using a statistical scanning method. The optimization of the separation over the experimental region is based on a special polynomial estimation from seven experimental runs, and resolution (Rs) is used as the selection criterion. Excellent agreement was obtained between predicted and experimental d

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160207

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

年代:1998

数据来源: WILEY

摘要:

AbstractA model peptide, TDK, was studied by circular dichroism to elucidate the effect of organic solvent on α‐helical formation. The a‐helicities enhanced by various alcohol solvents, especially fluorine‐substituted alcohols were systematically compared. The relations between a‐helical formation of a peptide and external environment were also discussed in detail. These environmental elements mainly include hydrophobicity, dielectric constant and acidity of the

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160208

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

年代:1998

数据来源: WILEY

摘要:

AbstractSeveral new tetrahydroisoquinolinium salts, analogues of atracurium, were designed and synthesized. These compounds were prepared from optically pure tetrahydropapaverine and hexamethylene diglycidate.

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160209

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

年代:1998

数据来源: WILEY

摘要:

AbstractIn order to get good antitumor agents especially better than 5‐fluorouracil, tegafur and l‐hexylcarbamoyl‐5‐fluorouracil (HCFU), fourty nine 1‐carbamoyl‐5‐fluorouracil having aromatic ring were synthesized from 5‐fluorouracil and isocyanates or mines. Antitumor activity was tested in the L1210 tumor system, and 5 compounds gave better value of therapeutic ratio than 5‐fluorouracil, tegafur, HCFU. 1‐(4‐Methoxybenzylcarbamoyl)‐5‐fluorour

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160210

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

年代:1998

数据来源: WILEY

摘要:

Abstract1,3‐Dipolar cycloaddition to C70of an azomethine ylide, which was generatedin situfrom refluxing a mixture of cyclohexanone andDL‐valine in chlorobenzene under N2, afforded a monoadduct and a bisadduct. Even for longer reaction time, however, only monoadduct waa obtained from the reaction of C70with an azomethine ylide generated from refluxing a mixture of 2‐undecanone and 2‐aminoisobutyric acid in chlorobenzene under N2. The electrochemical properties of all the products were studied by cyclic volt

ISSN:1001-604X    

DOI:10.1002/cjoc.19980160211

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

年代:1998

数据来源: WILEY