Distance-Dependent Electronic Interactions Across DNA Base Pairs: Charge Transport,Exciton Coupling,and Energy Transfer

The π-stacked bases of B-DNA constitute a helical ruler present nowhere else in nature. When two chromophores are placed at the ends of a base-pair domain with fixed orientations of their transition dipole moments, insertion of an additional base pair between the chromophores increases the distance between the chromophores by ca. 3.4 Å and the angle between their transition dipoles by ca. 36°. The consequences of these changes on the dynamics and efficiency of photoinduced charge transport and upon exciton-coupled circular dichroism and fluorescence resonance energy transfer are discussed.