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Issue 30, 2012
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Ultrafast nonradiative decay by hypoxanthine and several methylxanthines in aqueous and acetonitrile solution

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Abstract

Excited state lifetimes of hypoxanthine and four methylxanthine compounds (paraxanthine, theophylline, theobromine, and caffeine) were studied by femtosecond transient absorption spectroscopy in aqueous and acetonitrile solution. Transient absorption signals recorded at visible and UV probe wavelengths reveal that internal conversion from the photoexcited state to the electronic ground state takes place in water on the hundreds of femtoseconds time scale. Excited-state relaxation occurs approximately threefold more slowly in acetonitrile solution than in water. Structural considerations suggest that the deactivating conical intersection for the methylxanthines differs from that responsible for nonradiative decay by hypoxanthine, adenine, and guanine. All compounds studied have ultrashort excited state lifetimes similar to those of adenine and guanine, suggesting that these xanthine derivatives could have been photostable building blocks in prebiotic environments exposed to intense UV radiation.

Graphical abstract: Ultrafast nonradiative decay by hypoxanthine and several methylxanthines in aqueous and acetonitrile solution

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Publication details

The article was received on 24 Apr 2012, accepted on 07 Jun 2012 and first published on 11 Jun 2012


Article type: Paper
DOI: 10.1039/C2CP41296A
Citation: Phys. Chem. Chem. Phys., 2012,14, 10677-10682

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    Ultrafast nonradiative decay by hypoxanthine and several methylxanthines in aqueous and acetonitrile solution

    J. Chen and B. Kohler, Phys. Chem. Chem. Phys., 2012, 14, 10677
    DOI: 10.1039/C2CP41296A

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