Stacking interaction of nucleobases: NMR investigations. III. Molecular aspects of the solvent dependence.

The stacking interaction between nucleic acid bases has been investigated by the determination of the self-association of 6-methylpurine in various mixtures of water and nonaqueous solvents in order to elucidate the solvent effect. The parameters of stacking association as well as of local solvent-solute interactions have been measured by means of NMR technique. The influences of local hydration and of solvent-solvent interactions on the stacking ability are discussed.