@article{7313,
  author = {G. C. P. van Zundert and S. Jaeqx and G. Berden and J. M. Bakker and K. Kleinermanns and J. Oomens and A. M. Rijs},
  title = {IR Spectroscopy of Isolated Neutral and Protonated Adenine and 9-Methyladenine},
  abstract = {IR spectroscopy is employed to study isolated adenine and its derivative 9-methyladenine in both their neutral and protonated forms. The IR spectra of neutral adenine and 9-methyladenine are measured in a molecular beam expansion via IR-UV ion-dip spectroscopy in the 525 to 1750 cm(-1) region. For adenine, UV excitation selects the 9H tautomer to give a conformer-selective IR spectrum. For 9-methyladenine, only one tautomer exists because of the methyl substitution at the N(9) position. The experimental spectra agree closely with spectra computed for these tautomers at the B3LYP/6-311++ G(df,pd) level of theory. These spectra complement previous tautomer-specific IR spectra in the hydrogen stretching range. The 9H-adenine spectrum obtained is compared to a previously recorded FTIR spectrum of adenine at 280 degrees C, which shows close agreement, although the 7H tautomer cannot be excluded from contributing. Protonated adenine and 9-methyladenine are generated by electrospray ionization and studied via IR multiple-photon dissociation (IRMPD) spectroscopy. Comparison of the experimental spectra with computed spectra allows identification of the protonation site, which suggests that the 1-9 tautomer is the dominant contributor to the spectra.},
  year = {2011},
  journal = {Chemphyschem},
  volume = {12},
  pages = {1921-1927},
  month = {Jul},
  isbn = {1439-4235},
  doi = {10.1002/cphc.201100133},
  language = {English},
}