The potential energy (PE) surfaces of the electronic ground and the lowest excited states relevant to photophysics of interconversion of the 2-hydroxypyridine/2(1H)-pyridone system are characterized by ab initio calculations. The energy calculations at the optimized geometries are performed with the aid of the second-order perturbation theory, employing the complete-active-space self-consistent-field (CASSCF) wave function as the reference (CASPT2). Results confirm the earlier hypothesis based on the CASSCF calculations (Chem. Phys. Lett. 1993, 211, 293) that the photoinduced dissociation-association (PIDA) mechanism is probably responsible for excited-state tautomerization observed in this system. Absorption of the second photon in the excited electronic state is suggested to provide the "driving" force for the PIDA mechanism.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry