A predictive screening tool to evaluate the efficiency of Z/E photoisomerizable molecular switches

The evaluation of the Z/E photoisomerization efficiency is an essential task to design photoactive molecular devices. Nevertheless, this photoreactivity can be correctly described only by applying extensive and expensive computational methods. In this study, a predictive tool to screen the photoinduced Z/E isomerization efficiency of molecular switches is presented, based on three key properties: the structure of the ground state minimum, the nature of the electronic transition populating the optically bright state, and the presence of crossings between the optically bright state and the one lower in energy. Our methodology allows evaluating these properties by few and affordable calculations, potentially enabling the screening of large sets of 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 derivatives. A comparison with the available experimental data is performed to validate our approach. Cis-trans photoisomerization is a key process for many processes in biology and materials science, but only careful and time-consuming quantum chemistry methods can describe such reaction in detail. Here, a predictive tool is presented requiring few and affordable calculations, evaluating the efficiency of paradigmatic and modified photoswitches.