The excited state properties of uracil, thymine and four analogous uracil compounds have been studied in acetonitrile by steady-state and time-resolved spectroscopy. The excited state lifetimes were measured using femtosecond UV fluorescence upconversion. The excited state lifetimes of uracil and its 1- and 3-methyl substituted derivatives are well described by one ultrafast (≤100 fs) component. Five substituted compounds show a more complex behavior, exhibiting longer excited state lifetimes and bi-exponential fluorescence decays. These longer decays are substantially faster in acetonitrile than in aqueous solution showing that the excited state deactivation mechanism is in part governed by the solvent. © 2006 Elsevier B.V. All rights reserved.

*** IBB - CNR ***

Laboratoire Francis Perrin, CEA/DSM/DRECAM/SPAM - CNRS URA 2453, CEA Saclay, F-91191 Gif-sur-Yvette, France

Dipartimento di Chimica, Universita Federico II, Complesso Universitario Monte S. Angelo, Via Cintia, I-80126 Napoli, Italy

Istituto Biostrutture e Bioimmagini, CNR, V. Mezzocannone 6, 80134 Napoli, Italy

Crespo-Hernandez, C.E., Cohen, B., Hare, P.M., Kohler, B., (2004) Chem. Rev., 104, p. 197

Pecourt, J.-M.L., Peon, J., Kohler, B., (2000) J. Am. Chem. Soc., 122, p. 9348

Malone, R.J., Miller, A.M., Kohler, B., (2003) Photochem. Photobiol., 77, p. 158

Cohen, B., Crespo-Hernandez, C.E., Kohler, B., (2004) Faraday Discuss. Chem. Soc., 127, p. 137

Crespo-Hernández, C.E., Kohler, B., (2004) J. Phys. Chem. B, 108, p. 11182

Blancafort, L., Cohen, B., Hare, P.M., Kohler, B., Robb, M.A., (2005) J. Phys. Chem. A, 109, p. 4431

Peon, J., Zewail, A.H., (2001) Chem. Phys. Lett., 348, p. 255

Pancur, T., Schwalb, N.K., Renth, F., Temps, F., (2005) Chem. Phys., 313, p. 199

Gustavsson, T., Sharonov, A., Markovitsi, D., (2002) Chem. Phys. Lett., 351, p. 195

Onidas, D., Markovitsi, D., Marguet, S., Sharonov, A., Gustavsson, T., (2002) J. Phys. Chem. B, 106, p. 11367

Matsika, S., (2004) J. Phys. Chem. A, 108, p. 7584

Matsika, S., (2005) J. Phys. Chem. A, 109, p. 7538

Improta, R., Barone, V., (2004) J. Am. Chem. Soc., 126, p. 14320

Zgierski, M.Z., Patchkovskii, S., Fujiwara, T., Lim, E.C., (2005) J. Phys. Chem. A, 109, p. 9384

Ismail, N., Blancafort, L., Olivucci, M., Kohler, B., Robb, M.A., (2002) J. Am. Chem. Soc., 124, p. 6818

Blancafort, L., Robb, M.A., (2004) J. Phys. Chem. A, 108, p. 10609

Marian, C.M., (2005) J. Chem. Phys., 122, p. 104314

Marian, C., Nolting, D., Weinkauf, R., (2005) Phys. Chem. Chem. Phys., 7, p. 3306

Nielsen, S.B., Sølling, T.I., (2005) Chem. Phys. Chem., 6, p. 1276

Perun, S., Sobolewski, A.L., Domcke, W., (2005) Chem. Phys., 313, p. 107

Canuel, C., Mons, M., Piuzzi, F., Tardivel, B., Dimicoli, I., Elhanine, M., (2005) J. Chem. Phys., 122, p. 0743161

Häupl, T., Windolph, C., Jochum, T., Brede, O., Hermann, R., (1997) Chem. Phys. Lett., 280, p. 520

Gustavsson, T., Sarkar, N., Lazzarotto, E., Markovitsi, D., Barone, V., Improta, R., (2006) J. Phys. Chem. B, 110, p. 12843

Markovitsi, D., Onidas, D., Talbot, F., Marguet, S., Gustavsson, T., Lazzarotto, E., (2006) J. Photochem. Photobiol. A: Chem., 183, p. 1

Clark, L.B., Peschel, G.G., Tinoco, I., (1965) J. Phys. Chem., 69, p. 3615

Clark, L.B., Tinoco Jr., I., (1965) J. Am. Chem. Soc., 87, p. 11

Pecourt, J. -M. L., Peon, J., Kohler, B., (2000) J. Am. Chem. Soc., 122, p. 9348

Malone, R. J., Miller, A. M., Kohler, B., (2003) Photochem. Photobiol., 77, p. 158

Crespo-Hern ndez, C. E., Kohler, B., (2004) J. Phys. Chem. B, 108, p. 11182

Zgierski, M. Z., Patchkovskii, S., Fujiwara, T., Lim, E. C., (2005) J. Phys. Chem. A, 109, p. 9384

Marian, C. M., (2005) J. Chem. Phys., 122, p. 104314

Nielsen, S. B., S lling, T. I., (2005) Chem. Phys. Chem., 6, p. 1276

H upl, T., Windolph, C., Jochum, T., Brede, O., Hermann, R., (1997) Chem. Phys. Lett., 280, p. 520

Clark, L. B., Peschel, G. G., Tinoco, I., (1965) J. Phys. Chem., 69, p. 3615

Clark, L. B., Tinoco Jr., I., (1965) J. Am. Chem. Soc., 87, p. 11