Femto/Picosecond Transient Absorption Study of Ring‐Opening Dynamics in Perimidinespirocyclohexadienone Derivatives

Abstract

The ring-opening dynamics of perimidinespirocyclohexadienone derivatives has been studied by means of time-resolved spectroscopy in cyclohexane and acetonitrile solutions. It has been established that molecular isomerisation leading to the open isomer occurs against the background of the S 1-S 0 internal conversion of the cyclic form. In addition, the features of the observed spectral changes in the cyclohexane made it possible to distinguish formation of the photoproduct in the T 1 state and its relaxation via intersystem crossing to the singlet ground state. The corresponding assignments for transient absorption bands were performed on the basis of TD-DFT calculations.