DNA Charge Transport. Putting all the Pieces Together
2018 Edinburgh Instruments Lecture in Photophysics and Photochemistry: Professor Frederick D. Lewis (Northwestern University, Dept. of Chemistry)
Host: Professor Michael Therien
Friday, April 20, 2018 - 5:00pm to 6:30pm
Location: French Family Science Center 2231
Rosenthal, Janet

Link for Professor Lewis

Abstract:  Two decades ago several Northwestern colleagues began a collaborative investigation of photoinduced charge separation in DNA.  Initial studies employed femtosecond transient absorption spectroscopy to determine composite charge separation and charge recombination times for DNA hairpins possessing aromatic hydrocarbon linkers serving as hole donors and the natural base guanine as the hole acceptor.  Since no intermediates were observed in the charge separation process, it was assumed to occur as a single step process – superexchange or tunneling.  Subsequent studies both of DNA strand cleavage and of the dynamics of charge separation and charge transport over multiple bases served to eliminate tunneling as the likely mechanism except at short distances.  Advances in synthetic DNA hairpin design and in transient spectroscopy have made it possible to directly observe all of the key intermediates in the charge separation processes: the initially-formed contact radical-ion pair, the final charge-separated state, and both the localized and delocalized purine cation radicals which are the essential hole carriers in the charge separation process.  The synergy between advances in DNA structure, spectroscopy, and theory have provided the foundation for assembly of a unified theory.