Photoinduced DNA-mediated charge transport

The construction of well-defined DNA assemblies containing donors and acceptors at discrete sites on the helix allows the probing of DNA as a model of molecular wire. Barton et al. have designed a DNA duplex with a [Ru(bpy/phen)2(dppz)]2+ derivative as an electron donor and [Rh(phi)2(bpy/phen)]3+ derivative as an electron acceptor tethered by flexible linker to the opposite ends of the assembles [91,96, 97]. Both complexes were free to intercalate but separated by a fixed distance. The intercalation sites for both complexes were characterized by employing duplex DNA bearing a tethered ruthenium or rhodium complex. For ruthenium complexes 

The use of DNA molecules as wires in electronic systems may open a new opportunity in nanoelectronics. DNA has the appropriate molecular recognition features and well-characterized self-assembly. There is evidence to suggest that DNA is only a marginally better electron conductor than proteins [116-118], As a result, many studies have focused on various methods of DNA modification leading to improvement in its conductive properties. It is possible to enhance the conductivity of DNA by coating it with a thin film of metal atoms, but the molecular recognition properties of the DNA are then destroyed. An effective approach to this problem is the incorporation of metal ions into the DNA double helix [118-121], Preliminary results suggest that a metal ion-DNA complex may be a much better conductor than B-DNA, because the former shows a metallic conduction whereas the latter behaves like a wide-band gap semiconductor [118]. 

Szacilowski K, Macyk W, Drzewiecka-Matuszek A, Brindell M, Stochel G. Bioinorganic Photochemistry. Frontiers and Mechanisms. Chem Rev 2005 105 2647-94. 

Pogozelski WK, Thomas DT. Oxidative strand scission of nucleic acids routes initiated by hydrogen abstraction from sugar moiety. Chem Rev 1998 98 1089-107. 

Burrows CJ, Muller JG. Oxidative nucleobase modifications leading to strand scission. Chem Rev 1998 98 1109-51. 

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