Abstract:
The mechanisms of the photocolouring reactions of spiropyrans are considered and the vibrational mechanism for the dissociation of the C(2)–O bond in spiropyrans is analysed taking into account the relative positions of the π,π* and n,π* levels. The nature of the photochemically active state in spiropyrans has been established by examining the electronic nature of the low-lying excited states in organic molecules with heteroatoms. A mechanism is proposed for the photocolouring of spiropyrans, which explains the dependence of the efficiency of the C(2)–O bond dissociation reaction in spiropyrans on their structure. The bibliography includes 63 references.