Controllable selectivity of photosensitized oxidation of olefins included in vesicles
Li, HR; Wu, LZ; Tung, CH
Source PublicationTETRAHEDRON
Abstract9,10-Dicyanoanthracene (DCA) sensitized photooxidation of alpha-pinene, trans-stilbene and trans,trans-1,4-diphenyl-1,3-butadiene in mixed surfactant vesicles was investigated. While the oxidation in homogeneous solution yields the products derived from both the energy transfer and the electron transfer pathways, that within vesicles selectively yields either the singlet oxygen mediated or the superoxide radical anion mediated products depending on the status and location of the substrate and sensitizer molecules in the reaction medium. Upon incorporating the alkene in the bilayer membranes of one set of vesicles and DCA in another set of vesicles, the isolation of the substrate from the sensitizer prevents them from undergoing electron transfer. The singlet oxygen produced in the DCA-containing vesicles diffuses into the alkene-containing vesicles and reacts with the alkene. Thus, only the singlet oxygen oxidation products are obtained, and no product derived from the superoxide radical anion is detected. In contrast, incorporating both the sensitizer and the substrate within the same set of vesicles results in the two dissimilar molecules close to one another in the restricted space of the bilayer membranes of the vesicles. Thus, electron transfer from the alkenes to (1)DCA* is enhanced, and the efficiency of the intersystem crossing from (1)DCA* to (3)DCA* is reduced. The photosensitized oxidation in this case only gives the products derived from the electron transfer pathway. Moreover, the reaction of singlet oxygen with DPB in vesicles results exclusively in the 1,2-cycloaddition products rather than the 1,4-cycloaddition product. This result indicates that the organized semirigid environment in vesicles prevents the olefin molecules from conformational change. (C) 2000 Elsevier Science Ltd. All rights reserved.
KeywordSelective Oxidation Olefins Vesicles
Indexed BySCI
WOS IDWOS:000089340900011
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Cited Times:17[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Corresponding AuthorTung, CH
Affiliation1.Chinese Acad Sci, Inst Photog Chem, Beijing 100101, Peoples R China
2.Chinese Acad Sci, Inst Chem, Ctr Mol Sci, Beijing 100080, Peoples R China
Recommended Citation
GB/T 7714
Li, HR,Wu, LZ,Tung, CH. Controllable selectivity of photosensitized oxidation of olefins included in vesicles[J]. TETRAHEDRON,2000,56(38):7437-7442.
APA Li, HR,Wu, LZ,&Tung, CH.(2000).Controllable selectivity of photosensitized oxidation of olefins included in vesicles.TETRAHEDRON,56(38),7437-7442.
MLA Li, HR,et al."Controllable selectivity of photosensitized oxidation of olefins included in vesicles".TETRAHEDRON 56.38(2000):7437-7442.
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