摘要:

The efficiency of photoinduced charge separation across surfactant interfaces of micelles and vesicles depends in part on the location of electron donors and acceptors relative to the interface. Achievement and assessment of control of such location by the addition of pendant alkyl chains to donors and acceptors are reviewed. The net photo-ionization efficiency can be measured by electron spin resonance of radical ions in frozen surfactant solutions. Assessment of relative locations of radical ions with respect to a surfactant interface has been achieved by analysis of electron spin-echo modulation with deuterated water at the interface. Alkylmethylviologen electron acceptors are shown to be particularly useful for location control of photo-ionization efficiency in vesicles and less so in micelles. Electron donors investigated for location control include alkylated rutheniumtris(bipyridyl) species and alkylphenothiazine sulphonate derivatives. Photoinduced conversion of alkylmethylviologen radical ion to surfactant radicals is shown to enhance the net photo-ionization efficiency. Comparative photo-ionization efficiency results in vesicles, micelles and reverse micelles reveal structural aspects of effective location control by pendant alkyl chains.

ISSN:0144-235X    

DOI:10.1080/01442359009353249

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Recent investigations into the reactions of alkyl radicals are reviewed. Reactions discussed are: heats of formation, association, addition, dissociation, hydrogen atom transfer and oxidation. A trend towards the greater use of direct time-resolved methods for measuring rate coefficients is noted and future developments, based on the availability of high-qualityab initiopotential energy surfaces, are anticipated.

ISSN:0144-235X    

DOI:10.1080/01442359009353250

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The far-infrared spectra of a series of haloacetyl halides, CH2XC(O)X, in the vapour phase have been recorded at a resolution of 0-10cm−1in the 350-35 cm−1region. The fundamental asymmetric torsional frequencies of the more stabletrans(two halogen atoms orientedtransto one another) and high-energy conformers have been observed. From these data the asymmetric torsional potential functions governing internal rotation about the C-C bond have been determined. Only fiuoroacetyl fluoride and fluoroacetyl chloride have thecisconformation for the high-energy form whereas all the other haloacetyl halides have thegaucheconformation for the high-energy form. For those molecules in this series which have thegaucheform as the high-energy rotamer the importance of using the value for the torsional dihedral angle in the determination of the potential function governing internal rotation is reviewed. It is shown how complete equilibrium geometries, which have been determined byab initioHartree-Fock gradient calculations, can be used in conjunction with microwave and/or electron diffraction studies to obtain more reliable experimental structural parameters for these molecules. Finally, the reliability of theab initiotechniques used at predicting trends in the optimized geometries and potential functions governing internal rotation are assessed.

ISSN:0144-235X    

DOI:10.1080/01442359009353251

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0144-235X    

DOI:10.1080/01442359009353252

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor