- Molecular recognition studies on supramolecular systems. 32. Molecular recognition of dyes by organoselenium-bridged bis(β-cyclodextrin)s
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A series of novel bis(β-cyclodextrin)s tethered with organoselenium linkers, i.e., 6,6′-(o-phenylenediseleno)-bridged bis(β-cyclodextrin) (2), 6,6′-[2,2′-diselenobis(benzoyloxy)]-bridged bis(β-cyclodextrin) (3), and 6,6′-[2,2′-diselenobis[2-(benzoylamino)ethylamino]]-bridged bis(β-cyclodextrin) (4), were synthesized from β-cyclodextrin (1). The inclusion complexation behavior of 1-4 with some dyes, such as 8-anilinonaphthalenesulfonate (ANS), Brilliant Green, Crystal Violet, Tropaeolin OO, Auramine O, and Methyl Orange, was investigated in aqueous phosphate buffer solution (pH 7.20) at 25 °C by UV-vis, fluorescence, and circular dichroism spectrometry, as well as fluorescence lifetime measurements. The complex stability constants (KS) and Gibbs free energy changes (δG°) for the stoichiometric 1:1 inclusion complexation of 1-4 with the dyes were obtained by the spectrophotometric or spectropolarimetric titrations. The bis(β-cyclodextrin)s 2-4 showed much higher affinities toward these guest dyes than native β-cyclodextrin I with fairly good molecular selectivities. The cooperative binding abilities of these bis(β-cyclodextrin)s are discussed from the viewpoints of size/shape-fit interaction, induced-fit concept, and multiple recognition mechanism.
- Liu,Li,You,Wada,Inoue
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- Glow Discharge Plasma Reduction of Viologen Homologues and Organic Dyes in Solid and Solvated States
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A variety of viologen homologues (1,1'-disubstituted 4.4'-dipyridinium ions) were reduced both in solid and in DMF solution by a radio-frequency gaseous plasma.Reduction occured very rapidly and quantitatively with plasma exposure and resulted in the corresponding cation radicals.These radicals were oxidized on exposure to air but reduced again with repeated plasma exposure indicating that the reduction is an one-electron process.In a similar manner organic compounds such as methylene blue and brilliant green were also reduced effectively by the plasma.From kinetic study and ESR measurements approximate electron concentrations responsible for the reduction in the plasma were estimated.
- Osada, Yoshihito,Iriyama, Yu
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p. 5951 - 5956
(2007/10/02)
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