title: Efficient photosensitized splitting of the thymine dimer/oxetane unit on its modifying beta-cyclodextrin by a binding electron donor.
abstract: Two modified beta-cyclodextrins (beta-CDs) with a thymine dimer and a thymine oxetane adduct respectively, TD-CD and Ox-CD, have been prepared, and utilized to bind an electron-rich chromophore, indole or N,N-dimethylaniline (DMA), to form a supramolecular complex. We have examined the photosensitized splitting of the dimer/oxetane unit in TD-CD/Ox-CD by indole or DMA via an electron-transfer pathway, and observed high splitting efficiencies of the dimer/oxetane unit. On the basis of measurements of fluorescence spectra and splitting quantum yields, it is suggested that the splitting reaction occurs in a supramolecular complex by an inclusion interaction between the modified beta-CDs and DMA or indole. The back electron transfer, which leads low splitting efficiencies for the covalently-linked chromophore-dimer/oxetane compounds, is suppressed in the non-covalently-bound complex, and the mechanism has been discussed.
authors.affiliation: Department of Chemistry, University of Science and Technology of China, and State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Hefei, Anhui. qhsong@ustc.edu.cn.
authors.forename: Wen-Jian
authors.initials: WJ
authors.lastname: Tang
authors.forename: Qin-Hua
authors.initials: QH
authors.lastname: Song
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Wang
authors.forename: Jing-Yu
authors.initials: JY
authors.lastname: Yu
authors.forename: Qing-Xiang
authors.initials: QX
authors.lastname: Guo
mesh_terms: D004583:Electrons; D004988:Ethers, Cyclic / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D010777:Photochemistry; D011740:Pyrimidine Dimers / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013056:Spectrophotometry, Ultraviolet; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D004988:Ethers, Cyclic; D011740:Pyrimidine Dimers; D047392:beta-Cyclodextrins; C005287:oxetane; C031215:betadex