Abstract
The vibronic spectrum of the adenine-thymine (A-T) base pair was obtained by one-color resonant two-photon ionization (R2PI) spectroscopy in a free jet of thermally evaporated A and T under conditions favorable for formation of small clusters. The onset of the spectrum at 35 064 cm-1 exhibits a large red shift relative to the π-π* origin of 9H-adenine at 36 105 cm-1. The IR-UV spectrum was assigned to cluster structures with HNH ⋯ O=C/N ⋯ HN hydrogen bonding by comparison with the IR spectra of A and T monomers and with ab initio calculated vibrational spectra of the most stable A-T isomers. The Watson-Crick A-T base pair is not the most stable base-pair structure at different levels of ab initio theory, and its vibrational spectrum. Experiments with methylated A and T were performed to further support the structural assignment.
Original language | English |
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Pages (from-to) | 838-842 |
Number of pages | 5 |
Journal | ChemPhysChem |
Volume | 4 |
Issue number | 8 |
DOIs | |
State | Published - 18 Aug 2003 |
Externally published | Yes |
Keywords
- Ab initio calculations
- IR spectroscopy
- Laser spectroscopy
- Nucleobases
- UV/Vis spectroscopy
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry