A time-resolved electron spin resonance study of the triplet states of quinoline, isoquinoline, their protonated cations and naphthalene

Abstract

Transient ESR spectra have been observed for the lowest triplet states of naphthalene, quinoline (QN), quinolinium (QNH +), isoquinoline (iso-QN) and isoquinolinium (iso-QNH +) in ethanol at 77 K. using a time-resolved ESR technique. With the aid of computer simulations, it is concluded that, following the protonation of QN, the sublevel initially populated by S 1→T 1 intersystem crossing changes from T y in QN to T z in QNH + ( y and z are close to the long and short in-plane molecular axes, respectively).