Influence of High Pressure on the Pedal-like Motion and Photoreactivity in the Cocrystals of 1,2-Di(4-pyridyl)ethylene with trans-2-(4-Fluorophenyl)vinylboronic Acid

The photochemical properties of 1,2-di(4-pyridyl)ethylene (bpe) and trans-2-(4-fluorophenyl)vinylboronic acid (fpvb) cocrystals have been investigated using complementary techniques: single-crystal X-ray diffraction, including high-pressure experiments, solid-state and solution nuclear magnetic resonance, and density functional theory calculations. The photochemistry of bpe and fpvb cocrystals strongly depends on the arrangement of bpe molecules. The [2 + 2] photodimerization of bpe occurs in the case of the bpe/fpvb ratio of 1:1, while a ratio of 1:2 is observed in photoinert objects. In the photoreactive cocrystals, a pedal-like motion occurs in bpe molecules. This phenomenon strongly affects photoreactivity because it changes the mutual geometry of two reactant molecules. The intermolecular geometry and the kinetics of the pedal-like motion, and thereby, the kinetics of the [2 + 2] photodimerization of bpe, have been modified by means of high pressure.