Study of iodide as selective quencher of triplet excited states of pterin and lumazine

M. PAULA DENOFRIO; CAROLINA LORENTE; PETER R. OGILBY; ANDRéS H. THOMAS

Encuentro; XI Encuentro Latinoamericano de Fotoquímica y Fotobiología (ELAFOT); 2012

It has been demonstrated that pteridines are able to act as efficient sensitizers in photoinduced oxidations. These processes havebeen well characterized for thosecases where it was used 2-aminopteridine-4(3H)-one (pterin; denoted Ptr) and pteridine-2,4(1,3H)-dione (lumazine; denoted Lum). as photosensitizers and the nucleotides 2′-deoxyguanosine 5′-monophosphate (dGMP) and 2′-deoxyadenosine 5′-monophosphate (dAMP) as targets.(1-5) It is interesting to establish the nature, singlet (1S*) or triplet (3T*), of the electronic excited states involved in such processes. In this regard, the development and optimization of routine techniques that allow distinguishing from which excited state the photosensitization occurs becomes relevant. In thissense, a good example is the use of certain species which under controlled working conditions can deactivate selectively an excited electronic state.(6) In this work, we present results of the selective deactivationof triplet excited states of Ptr and Lumby iodide anion. The method was applied to the reactions of dGMPand dAMP photosensitizationpreviously studied.           (1) Petroselli, G.; Erra-Balsells, R.; Cabrerizo, F. M.; Lorente, C.; Capparelli, A. L.; Braun, A. M.; Oliveros, E.; Thomas, A. H. Org. Biomol. Chem. (2007), 5, 2792-2799. (2) Gabriela Petroselli, M. Laura Dantola, Franco M. Cabrerizo, Alberto L. Capparelli, Carolina Lorente, Esther Oliveros and Andres H. Thomas, J. Am. Chem. Soc. (2008), 130, 3001-3011. (3) M. P. Denofrio, S. Hatz, C. Lorente, F. M. Cabrerizo, P. R. Ogilby, A. H. Thomas, Photochem. Photobiol. Sci. (2009), 8, 1539?1549. (4) M. P. Denofrio, A. H. Thomas, C. Lorente, J. Phys. Chem. A (2010), 114,10944?10950. (5) M. Paula Denofrio, M. Laura Dántola, Patricia Vicendo, Esther Oliveros,Andrés H. Thomas and Carolina Lorente. Photochem. Photobiol. Sci., (2012), 11, 409 (6) M. S. Kritsky, T. A. Lyudnikova, E. A. Mironov and I. V. Moskaleva, J. Photochem. Photobiol., B, (1997), 39, 43?48.