Circular dichroism of nucleoside derivatives. VI. The optically active bands of adenine nucleoside derivatives.

The circular dichroism data on 17 adenine nucleosides show that the 260- and 207-mmu absorption systems of the adenine chromophore each contain at least two electronic transitions. The CD maxima are commonly found at around 260, 220, and 200 mmu, and occasionally at 240 mmu. Solvent studies suggest that these CD bands arise from pi-pi(*) transitions. A weak absorption band that obeys the McConnell criteria of an n-pi(*) band is resolved at about 290 mmu in hydrocarbon solvents. This band exhibits very little rotatory power.