Direct Observation of the Primary Bond-Twisting Dynamics of Stilbene Anion Radical

Electrocatalytic oxidative Z/E isomerization of a stilbene favoured by the presence of an electroactive persistent radical

A push-pull-functionalized stilbene has been prepared, with an electroactive perchlorotriphenylmethyl (PTM˙) radical and dimethylamine units as electron-withdrawing and -donating moieties, respectively, showing an electrocatalytic redox-induced Z→E isomerization where the open-shell nature of PTM˙ plays a key role in the isomerization ocurrance.

Electronic effects on photochemistry: the diverse reaction dynamics of highly excited stilbenes and azobenzene

Ultrafast time-resolved mass spectrometry and structural dynamics experiments on trans-stilbene, cis-stilbene, and azobenzene, with excitation to high-lying electronic states, reveal a rich diversity of photochemical reaction dynamics. All processes are found to be quite unlike the well-known photochemistry on lower electronic surfaces. While in trans-stilbene, excitation at 6 eV induces a phenyl twisting motion, in cis-stilbene it leads to an ultrafast ring-closing to form 4a,4b-dihydrophenanthrene. Azobenzene dissociates on an ultrafast time scale, rather than isomerizing as it does on a lower surface. The photochemical dynamics of the sample molecules proceed along steep potential energy surfaces and conical intersections. Because of that, the dynamics are much faster than vibrational relaxation, the randomizing effects from vibrational energy scrambling are avoided, and excitation-energy specific reaction dynamics results.