| Research Abstract |
In this study, I have proposed a new strategy of asymmetric photochemistry or a new concept of "supramolecular photochirogenesis," in which the chiral information of biomolecules is transferred to or multiplied in photoproducts through the solution-phase supramolecular interaction of chiral biomolecular hosts with prochiral guest substrates and the subsequent Uni.- and bimolecular photochemical reactions of the resulting host-guest complexes. All of the examined supramolecular photochirogenic approaches, employing modified cyclodextrins, (oligo)nucleotides, DNA, RNA, and protein as chiral biomolecular hosts, were successful in creating optically active photoproducts in good optical yields. Thus, the original idea of using the supramolecular interactions of chiral biomolecules in photochemical asymmetric synthesis has been demonstrated to be useful as a novel photochirogenic methodology, and is potentially extended to the other supramolecular systems. The major findings obtained in this
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thesis may be summarized as follows.
Chapter 1 is devoted to the supramolecular enantiodifferentiating photoisomerization of (Z)-cyclooctene included and sensitized by several modified α-,β-, and/or γ-cyclodextrins possessing a variety of chromophores. The inclusion complexation behavior and the subsequent enantiodifferentiating photosensitization mechanism are discussed in detail on the basis of the substituent, solvent, and temperature effects.
In Chapter 2, the same enantiodifferentiating photoisomerization of (Z)-cyclooctene to the chiral (E)-isomer was employed as a model system to assess the sensitizing and enantiodifferentiating abilities of double stranded DNA in aqueous solution. The sensitizing and enantiodifferentiating abilities of the relevant nucleosides and single- and double-stranded oligonucleotides of different sequences are also examined to assess the origin of enantiodifferentiating photoisomerization by DNA. A novel supramolecular enantiodifferentiating photoisomerization system, employing oligonucleotides, and DNA, will be proposed.
In Chapter 3 and 4, a novel bimolecular supramolecular asymmetric photocyclodimerization of 2-anthracenecarboxylate(AC) bound to bovine and human serum albumin (BSA, HSA) and is investigated in aqueous solutions. The binding behavior of AC to BSA and HSA in aqueous solutions is first assessed and the supramolecular enantioselective photocyclodimerization is performed under a variety of conditions in order to clarify the mechanisms of binding and the subsequent photoreactions to give the optically active photocyclodimers of AC. Less
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