Photophysics in the Presence of DNA and Mononucleotides

Emission quenching is also observed with mononucleotides. In that case the quenching efficiency decreases from GMP (guanosine 5 monophosphate) to AMP (adenosine 5 monophosphate) i.e. it also follows the redox potentials of the bases, as G is more easily oxidisable than A, although the oxidation potential valura reported in the literature are rather different from one author to the other [101-104], Moreover the quenching rate constant by GMP in a Kries of different TAP and HAT complexes plotted versus the reduction potential of the excited state (Fig. 12) [95] is consistent with an electron transfer process. Indeed, as will be demonstrated in Sect. 4.3.1, these quenchings (by the mono-and polynucleotides) originate from such processes. 

3 Photo-Electron Transfer Precedes in the Presence of Mononucleotides and DNA 

In this Section, two types of photo-electron transfer processes with the MLCT state of complexes will be successively discussed. We will first introduce the direct photo-electron transfer from a DNA base to the excited complex Sect. 4.3.1. Afterwards we will coiKider the electron transfer between an excited 

1 Photo-Electron Transfer from a DNA Base to the Excited Complex 

The photoreactions of Ru(TAP)3 in the presence of different mononucleotides have been used as models for the photoreactivity with CT-DNA and polynucleotides and for the photoreactions of other oxidising polyazaaromatic Ru(II) complexes [100]. Flash photolysis experiments with RufTAP) in the presence of GMP or AMP, demonstrate clearly the presence of a photo-induced 

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