Binding Energies of the pi-Stacked Anisole Dimer: New Molecular Beam-Laser Spectroscopy Experiments and CCSD(T) Calculations

Research output: Research - peer-reviewArticle

  • Authors:
  • Klaus Muller-Dethlefs
  • Jan Rezac
  • Dana Nachtigallova
  • Federico Mazzoni
  • Massimiliano Pasquini
  • And 4 others
  • External authors:
  • Giangaetano Pietraperzia
  • Maurizio Becucci
  • Klaus Mueller-Dethlefs
  • Pavel Hobza

Abstract

Among noncovalent interactions, pi-pi stacking is a very important binding motif governed mainly by London dispersion. Despite its importance, for instance, for the structure of bio-macromolecules, the direct experimental measurement of binding energies in pi-pi stacked complexes has been elusive for a long time. Only recently, an experimental value for the binding energy of the anisole dimer was presented, determined by velocity mapping ion imaging in a two-photon resonant ionisation molecular beam experiment. However, in that paper, a discrepancy was already noted between the obtained experimental value and a theoretical estimate. Here, we present an accurate recalculation of the binding energy based on the combination of the CCSD(T)/CBS interaction energy and a DFT-D3 vibrational analysis. This proves unambiguously that the previously reported experimental value is too high and a new series of measurements with a different, more sensitive apparatus was performed. The new experimental value of 1800 +/- 100 cm(-1) (5.15 +/- 0.29 kcal mol(-1)) is close to the present theoretical prediction of 5.04 +/- 0.40 kcal mol(-1). Additional calculations of the properties of the cationic and excited states involved in the photodissociation of the dimer were used to identify and rationalise the difficulties encountered in the experimental work.

Bibliographical metadata

Original languageEnglish
Pages (from-to)6740-6746
Number of pages7
JournalChemistry: A European Journal
Volume21
Issue number18
DOIs
StatePublished - 2015