Long-range charge transfer through DNA by replacing adenine with diaminopurine.

A positive charge migrates along DNA mainly via a series of short-range charge transfer (CT) processes between G-C base pairs, which have relatively high HOMO levels. As such, the CT efficiency sharply decreases with the insertion of A-T base pairs between the G-C base pairs. We have previously demonstrated that the CT efficiency through DNA can be dramatically increased by using deazaadenine (Z), an analogue of A, to adjust the HOMO levels of the A-T base pairs closer to those of the G-C base pairs (Nat. Chem. 2009, 1, 156). In the present study, we have expanded this approach to show that the CT efficiency can also be increased by replacing A bases with diaminopurine (D).