Dynamics of ultrafast singlet and triplet charge transfer in anthraquinone-DNA conjugates.

The efficiency of singlet and triplet charge radical ion-pair formation and the dynamics of radical-pair charge recombination in DNA-anthraquinone conjugates have been investigated by means of femtosecond time-resolved transient absorption spectroscopy. Singlet charge separation is more efficient than intersystem crossing, resulting in inefficient formation of the long-lived triplet radical ion pair. Both singlet charge separation and charge recombination are faster when guanine rather than adenine is the neighboring purine base.