A Predictive Screening Tool to Evaluate the Efficiency of Z/E Photoisomerizable Molecular Switches

Abstract The evaluation of the Z/E photoisomerization efficiency is an essential task to design novel photoactive molecular devices based on this type of photoreactivity. In this study, a predictive tool to screen the photoinduced Z/E isomerization efficiency of molecular switches is presented, based on three key properties: i) structure of the ground state minimum, ii) nature of the electronic transition populating the optically bright state, and iii) the presence of crossings between the optically bright state and the one lower in energy. Our methodology allows to calculate these properties by few and computationally affordable calculations, enabling the computational screening of large sets of potential photoswitches. After presenting the formal aspects, the tool is applied to model systems of paradigmatic classes of photoswitches (retinal, green fluorescent protein, hemithioindigo, chiroptical, and stilbene compounds), including novel derivatives. A comparison with the available experimental data is performed to validate our approach.