Effect of electron donating/withdrawing groups on molecular photoswitching of functionalized hemithioindigo derivatives: a computational multireference study

M. Lea, V. Stavros, R. J. Maurer, ChemPhotoChem, DOI: 10.1002/cptc.202100290 (2022)

"The mechanism of photoswitching for hemithioindigo cannot be described by pure dihedral rotation around the central carbon-carbon bond. A complementary motion, often pyramidalization, is required to facilitate radiationless internal conversion. This computational study, explores how the inclusion of electron-withdrawing and electron-donating substituents alters the excited state potential energy surfaces and the mechanism of photoisomerization. The predicted changes in energy landscapes reflect the acceleration or slowing of the photoisomerization process for different derivatives that is also observed in experiment."