Photoisomerization of cis,cis-and cis,trans-l,4-Di-o-tolyl-1,3-butadiene in Glassy Media at 77 K:One-Bond-Twist and Bicycle-Pedal Mechanisms

摘要

Viscous media enhance torsional barriers of olefins in the lowest excited singlet state and inhibit one-bond-twist (OBT) cis-trans photoisomerization.Two mechanisms involving concerted rotation about two bonds in S_1,initially postulated to explain retinyl photoisomerization within the protein environment in rhodopsin and bacteriorhodopsin,have been applied generally to account for photoisomerization in volume-confining media.