NMR and UV study of 1,1'-(alpha,omega-alkanediyl)bis[thymine] and 1,1'-(alpha,omega-alkanediyl)bis[uracil]

Treatment of thymine or uracil with Br(CH2)(n)Br (n = 3-10) in the presence of t-BuOK gave 1,1'-(alpha,omega-alkanediyl)bis[thymine] or 1,1'-(alpha,omega-alkanediyl)bis[uracil] together with 1-(omega-bromoalkyl)thymine or 1-(omega-bromoalkyl)uracil. The structures of these products were determined on the basis of the coupling constants between 5- and 5-positions of uracil ring on the H-1 NMR spectra. Molecular aggregation of the thymine and uracil rings of these compounds in aqueous solution was studied on the basis of their H-1 NMR and UV spectra. A stacking interaction of the two thymine rings linked by shorter polymethylene chains such as trimethylene and tetramenthylene groups was observed.