Modulation of Excess Electron Transfer through LUMO Gradients in DNA Containing Phenanthrenyl Base Surrogates

The modulation of excess electron transfer (EET) within DNA containing a dimethylaminopyrene (C-AP) as an electron donor and 5-bromouracil (^Br dU) as an electron acceptor through phenanthrenyl pairs (phen-R) could be achieved by modifying the phenanthrenyl base surrogates with electron withdrawing and donating groups. Arranging the phenanthrenyl units to form a descending LUMO gradient increased the EET efficiency compared to the electron transfer through uniform LUMOs or an ascending LUMO gradient.

Acceleration of Long-Range Photoinduced Electron Transfer through DNA by Hydroxyquinolines as Artificial Base Pairs

The C-nucleoside based on the hydroxyquinoline ligand (Hq) is complementary to itself and forms stable Hq-Hq pairs in double-stranded DNA. These artificial Hq-Hq pairs may serve as artificial electron carriers for long-range photoinduced electron transfer in DNA, as elucidated by a combination of gel electrophoretic analysis of irradiated samples and time-resolved transient absorption spectroscopy. For this study, the Hq-Hq pair was combined with a DNA-based donor-acceptor system consisting of 6-N,N-dimethylaminopyrene conjugated to 2'-deoxyuridine as photoinducible electron donor, and methyl viologen attached to the 2'-position of uridine as electron acceptor. The Hq radical anion was identified in the time-resolved measurements and strand cleavage products support its role as an intermediate charge carrier. Hence, the Hq-Hq pair significantly enhances the electron hopping capability of DNA compared to natural DNA bases over long distances while keeping the self-assembly properties as the most attractive feature of DNA as a supramolecular architecture.

Electron transport in DNA initiated by diaminonaphthalene donors alternatively bound by non-covalent and covalent association

Non-covalent association can identify active donors for study of charge transfer in DNA but may not establish detailed correlations between donor structure and transfer efficiency.

Controlling electron rebound within four-base π-stacks in Z-DNA by changing the sugar moiety from deoxy- to ribonucleotide

Charge transfer through DNA is of great interest because of the potential of DNA to be a building block for nanoelectronic sensors and devices. The photochemical reaction of 5-halouracil has been used for probing charge-transfer processes along DNA. We previously reported on unique charge transfer following photochemical reaction of 5-bromouracil within four-base π-stacks in Z-DNA. In this study, we incorporated a guanosine instead of a deoxyguanosine into Z-DNA, and found that electron transfer occurs in a different mechanism through four-base π-stacks.