Photophysics of phenylcycloalkenes. Effect of double-bond constraint

Abstract

The photophysics of 2-phenyl-2-norbornene in a low-temperature glass and in inert-gas matrices has been compared with the photophysics of 1-phenylcyclobutene and other styrene derivatives. Surprisingly, non-radiative relaxation from the S₁ level in phenylnorbornene was found to be more rapid than in the case of phenylcyclobutene. This result, together with the lack of phosphorescence from phenylnorbornene, even in a matrix at 10 K, indicates that in some styrenes non-radiative processes other than rotational relaxation may be very important.