Tautomerism of uracil probed via infrared spectroscopy of singly hydrated protonated uracil

Joost M. Bakker, Rajeev K. Sinha, Thierry Besson, Maurizio Brugnara, Paolo Tosi, Jean Yves Salpin, Philippe Maître

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95 Citations (Scopus)


Tautomerism of the nucleobase uracil is characterized in the gas phase through IR photodissociation spectroscopy of singly hydrated protonated uracil created with tandem mass spectrometric methods in a commercially available Fourier transform ion cyclotron resonance mass spectrometer. Protonated uracil ions generated by electrospray ionization are re-solvated in a low-pressure collision cell filled with a mixture of water vapor seeded in argon. Their structure is investigated by IR photodissociation spectroscopy in the NH and OH stretching region (2500-3800 cm-1) with a tabletop IR laser source and in the 1000-2000 cm-1 range with a free-electron laser. In both regions the IR photodissociation spectrum exhibits well-resolved spectral signatures that point to the presence of two different types of structure for monohydrated protonated uracil, which result from the two lowest-energy tautomers of uracil. Ab initio calculations confirm that no water-catalyzed tautomerization occurs during the re-solvation process, indicating that the two protonated forms of uracil directly originate from the electrospray process.

Original languageEnglish
Pages (from-to)12393-12400
Number of pages8
JournalJournal of Physical Chemistry A
Issue number48
Publication statusPublished - 04-12-2008

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry


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