| Abstract: | The photodimerization reaction of thymine bases incorporated in the modified oligo- and polyethyleneimines, in which α-alanine or ß-alanine unit was inserted between the main chain and the pendant thymine bases, was studied both in aqueous and in dimethyl sulfoxide solutions. It was found that the quantum yields for the photodimerization for the oligomers were closely related to the intramolecular interaction in the ground state, while those of the copolymers were not related to the ground state interaction. It was suggested that the singlet energy migration was present in the case of the polyethyleneimine derivatives. This result is discussed in terms of the effects of the nearest-neighboring thymine units, the structure of the side chain, and the singlet energy migration, particularly for the copolymers. |
