Photoreactive and Inactive Crystals of 1-Alkylthymine Derivatives

Abstract

Abstract Two kinds of crystal structures were found for 1-octylthymine from X-ray structure analysis: Structure I was obtained from Crystal I recrystallized from ethyl acetate, and Structure II was obtained from Crystal II recrystallized from ethanol. The thymine bases in Crystal I had high reactivity for photodimerization. Crystal II, however, was inactive for the photodimerization of thymine bases. This paper presents the crystal structure of 1-octylthymine crystallized from ethanol (Crystal II) by X-ray crystal structure analysis. Thymines in Crystal II were concluded to be inactive for photodimerization because of unsuitable orientation of thymine bases in the crystal and because of insufficient space for rotation of thymine during photodimerization.