Synthesis of 6-N-(benzothiazol-2-yl)deoxyadenosine and its exciton-coupled circular dichroism

6-N-(Benzothiazol-2-yl)deoxyadenosine (ABT) was synthesized and incorporated into DNAs. Although, the multipoint benzothiazole (BT) modification of oligodeoxynucleotides reduced the stability of duplexes with their complementary strands, it induced the strong exciton coupling between BT moieties. The circular dichroism (CD) spectra of this exciton coupling interaction were observed at wavelengths above 300 nm and overlapping with the UV absorption bands of nucleotides could be avoided. The shapes of the CD spectra due to this interaction were strongly influenced by the helicity of two BT groups.