jz8b02159_si_001.pdf (1.7 MB)
Twist and Return−Induced Ring Strain Triggers Quick Relaxation of a (Z)‑Stabilized Cyclobisazobenzene
journal contributionposted on 2018-07-31, 00:00 authored by Chavdar Slavov, Chong Yang, Andreas H. Heindl, Tim Stauch, Hermann A. Wegner, Andreas Dreuw, Josef Wachtveitl
Continuous irradiation of the thermodynamically stable (Z,Z)-cyclobisazobenzene does not lead to accumulation of a (Z,E) or (E,E) isomer as one might expect. Our combined experimental and computational investigation reveals that Z → E photoisomerization still takes place on an ultrafast time scale but induces large ring strain in the macrocycle, which leads to a very fast thermal back-isomerization, preventing photostationary accumulation of (E)-isomers.