Theoretical investigations of the proton transfer reaction in the hydrogen-bonded complex of 2-pyrimidinone with water
- Inst. of Physics, Warsaw (Poland)
- Univ. of Lund (Sweden)
The potential energy (PE) functions of the electronic ground and lowest {pi}{pi}{sup *} excited singlet states of the hydrogen-bonded cyclic complex of 2-pyrimidinone with water were theoretically investigated along the proton transfer (PT) reaction coordinate. The full geometry optimization was performed along the PT reaction path. In the geometry optimization the Hartree-Fock method and the configuration interaction method with single excitations (CIS) were used. The energy calculations at the optimized geometries were performed with the complete-active-space self-consistent-field (CASSCF) method and with the second-order perturbation theory, employing the CASSCF wave function as the reference. For the ground state, calculations were also performed with the Moller-Plesset second-order perturbation theory (MP2). We found that the hydroxy form of the 2-pyrimidinone:water complex is stable in the ground electronic state while the hydroxy-to-oxo transformation reaction of the complex is by about 0.67 eV exothermic on the lowest {sup 1} {pi}{pi}{sup *} excited state PE surface. However, there is a barrier of about 0.19 eV along the PT reaction path on this surface. The top of the barrier is below the energy of the vertical excitation S{sub o} {yields} {sup 1}{pi}{pi}{sup *}; thus, the photoexcited system has sufficient excess energy for the PT reaction to occur spontaneously. 25 refs., 5 figs., 6 tabs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG03-93ER61605
- OSTI ID:
- 121616
- Journal Information:
- Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 39 Vol. 99; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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