Extending the ‘Grochala–Albrecht–Hoffmann approximation’ to the determination of the first excited state potential energy profile of a reaction step

In this communication, a very simple method is proposed to calculate the potential energy profile of a reaction step for a system in its first electronic excited state. It is based on an extension of the Grochala–Albrecht–Hoffmann rule. Theoretical arguments supporting this extension are given. The proposed method is validated on two examples that are interesting from a biological point of view: photocycloadditions [2+2] involved in the formation of pyrimidic dimers under DNA exposition to UV radiation.