Photoisomerization of 2,3-diphenylcyclopropane-1-carboxylic acid derivatives

Abstract

Contrary to what is known about cis-1,2-diphenylcyclopropane and its derivatives, we find that they have triplet energies of ca. 311 kJ mol -1, do not undergo intersystem crossing upon direct excitation, undergo the less common adiabatic photoisomerization to the corresponding trans isomers, and show emission from excited 1,3-diradical intermediates. © The Royal Society of Chemistry and Owner Societies 2003.