The effect of hydration on the photo-deactivation pathways of 4-aminopyrimidine

Jaroslaw J. Szymczak, Thomas Müller, Hans Lischka

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13 Scopus citations


The influence of water on the photo-deactivation process of 4-aminopyrimidine has been investigated by means of microsolvation and continuum solvation models. Two- and four-water models were used for the former purpose. Vertical excitations, stationary points on the first excited singlet surface, conical intersections (minima on the crossing seam) and reaction paths have been investigated at the state-averaged complete active space self-consistent field (CASSCF) and multistate CAS perturbation theory to second order (MS-CASPT2) levels of theory. A destabilizing effect of 0.2-0.3 eV has been observed for nπ states while the ππ state is almost unaffected. The two-water model gives already a good representation of hydration effects, especially when combined with the continuum model. A small enhancement of energy barriers (∼0.1 eV) is observed leading to the conclusion that the photodynamics of 4-aminopyrimidine should be affected only little by these solvent effects.

Original languageEnglish
Pages (from-to)110-117
Number of pages8
JournalChemical Physics
Issue number1
StatePublished - Sep 14 2010


  • Conical intersection
  • Continuum solvation
  • Excited states
  • Hydrogen bonds
  • Microsolvation
  • Reaction path


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