The photochemistry of 1-cyano-2-methyl-3-phenylpropone and ring substituted derivatives

Abstract

The E- and Z-isormers of 1-cyano-2-methyl-3-phenylpropane and ring-substituted derivatives of the E-isomer, are shown to fluoresce and undergo Z–E-isomerization and di-π-methane rearrangement on irradiation. The rate constants for these processes, obtained from fluorescence lifetimes and quantum yields, can be analysed in terms of an initial interaction between the two π systems, facilitated by partial charge-transfer, followed by two diverging pathways, one, towards a diradicaloid species leading to cyclopropane formation, the other towards a ‘zwitterion’ is species and relaxation to the ground state and resulting in singlet state Z–E- isomerization.