Pulsed field ionization electron spectroscopy and molecular structure of aluminum uracil

Serge A. Krasnokutski, Dong Sheng Yang

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10 Scopus citations


Al-uracil (Al-C 4H 4N 2O 2) was synthesized in a laser-vaporization supersonic molecular beam source and studied with pulsed field ionization-zero electron kinetic energy (ZEKE) photoelectron spectroscopy and density functional theory (DFT). The DFT calculations predicted several low-energy Al-uracil isomers with Al binding to the diketo, keto-enol, and dienol tautomers of uracil. The ZEKE spectroscopic measurements of Al-uracil determined the ionization energy of 43 064(5) cm -1 [or 5.340(6) eV] and a vibrational mode of 51 cm -1 for the neutral complex and several vibrational modes of 51, 303, 614, and 739 cm -1 for the ionized species. Combination of the ZEEK spectrum with the DFT and Franck-Condon factor calculations determined the preferred isomeric structure and electronic states of the Al-uracil complex. This isomer is formed by Al binding to the 04 atom of the diketo tautomer of uracil and has a planar C s symmetry. The ground electronic states of the neutral and ionized species are 2A″ and 1A′, respectively. The 2A″ neutral state has a slightly shorter Al-O4 distance than the 1A′ ion state. However, the 1A′ ion state has stronger metal-ligand binding compared to the 2A″ state. The increased Al-O4 distance from the 2A″ state to the 1A′ state is attributed to the loss of the π binding interaction between Al and O4 in the singlet ion state, whereas the increased metal-ligand binding strength is due to the additional charge-dipole interaction in the ion that surpasses the loss of the π orbital interaction.

Original languageEnglish
Pages (from-to)10567-10573
Number of pages7
JournalJournal of Physical Chemistry A
Issue number42
StatePublished - Oct 25 2007

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry


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