Ab initio study of the cyclodimerization of uracil through butane-like and oxetane-like conical intersections

作者：Delchev Vassil B^*; Domcke Wolfgang

来源：Journal of Photochemistry and Photobiology A: Chemistry , 2013, 271: 1-7.

DOI：10.1016/j.jphotochem.2013.07.015

• Ab initio calculations
• Conical intersections
• Excited states
• Photocyclodimerization
• Uracil

In the present work we explored the mechanisms of the formations of the uracil cyclobutane and oxetane cyclodimers using ab initio methods through excited states and the S-0-S-1 conical intersections. The excited-state reaction paths showed that the (1)pi pi* excited states of the stacked dimers can relax, in a barrierless manner, to the ground states via S-0-S-1 conical intersections. We found that the destruction of the cyclodimers occurs through (1)pi pi* excited states and the same S-0-S-1 conical intersections. In other words, the formation and the destruction of the uracil cyclodimers are competitive reactions initiated by UV light. Excited-state reaction paths show that the production of the cyclobutane dimer is much more favorable than the oxetane adduct.

• 出版日期2013-11-1