Liquid Crystalline Solvents as Mechanistic Probes. 11. The Syn -> Anti Thermal Isomerization Mechanism of Some Low-"Bipolarity" Azobenzenes

Article abstract of DOI:10.1021/jo00168a015

The effects of solvent order on the syn -> anti isomerization rates of 15 azobenzenes have been investigated.The activation parameters determined in a cholesteric phase consisting of a 35/65 (w/w) mixture of cholesteryl chloride/cholesteryl nonanoate and in several other solvents are more consistent with an isomerization mechanism which proceeds via inversion (in plane) rather than rotation (out of plane).A correction of our previously reported data is given.The anomalous behavior of the isomerization mechanism of di-ortho-methylated azobenzenes is demonstrated by means of isokinetic plots.