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Fluorobenzene-nucleobase interactions: hydrogen bonding or pi-stacking?
Journal article

Fluorobenzene-nucleobase interactions: hydrogen bonding or pi-stacking?

  • Leist R Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
  • Frey JA
  • Leutwyler S
  • 2006-03-24
Published in:
  • The journal of physical chemistry. A. - 2006
Fluorobenzenes
Hydrogen Bonding
Molecular Structure
Nucleosides
Pyridones
Quantum Theory
Sensitivity and Specificity
Spectrometry, Fluorescence
Stereoisomerism
English Studies on modified DNA oligomers and polymerase reactions have previously demonstrated that canonical nucleobases can exhibit stable and even selective pairing with shape-complementary fluorobenzene nucleotides. Because of the fluorination of the pairing edges, hydrogen bonds are believed to be absent, and the local DNA stability has been attributed to pi-stacking and shape complementarity. Using two-color resonant two-photon ionization and fluorescence emission spectroscopies, we show here that supersonically cooled complexes of the nucleobase analogue 2-pyridone with seven substituted fluorobenzenes (1-fluorobenzene, 1,2- and 1,4-difluorobenzene, 1,3,5- and 1,2,3-trifluorobenzene, 1,2,4,5- and 1,2,3,4-tetrafluorobenzene) are hydrogen-bonded and not pi-stacked. The S1 <--> S0 vibronic spectra show intermolecular vibrational frequencies that are characteristic for doubly hydrogen bonded complexes. The bands shift to the blue with increasing hydrogen-bond strength; the measured spectral blue shifts deltanu are in excellent agreement with the ab initio calculated shifts. The spectral shifts are also linearly correlated with the calculated hydrogen-bond dissociation energies D0, published in a companion paper (Frey, J. A.; Leist, R.; Leutwyler, S. J. Phys. Chem. A 2006, 110, 4188). This correlation allows us to reliably estimate the ground-state dissociation energies as D0 approximately 6 kcal/mol of the 2-pyridone.fluorobenzene complexes from the observed spectral shifts.
Language
  • English
Open access status
closed
Identifiers
Persistent URL
https://folia.unifr.ch/global/documents/192290
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