future investigations in the optimization of biomimetic photoswitches potentially useful in modern light-induced therapeutic strategies INTRODUCTION During last decades, molecular switches have gained an increased interest as molecular agents capable to convert an external stimulus into a useful mechanical action. Molecular switches can lead to an extremely high spatial and temporal selectivity, even reaching the single molecule resolution, hence they allow a way to precisely manipulate complex molecular systems and aggregates. Furthermore, different stimuli can be used to trigger the conformational changes at the base of the switching action, including temperature changes, pH gradient, as well as the application of electrochemical or optical perturbations. The specific use of light to initiate and control a swiching action is at the base of photo-active molecular switches functioning, also known as photo-switches. In this case, the absorption of visible or near-UV photons, results in the population of an excited state manifold which may evolve to open ground-state forbidden reactive channels leading to chemical reactions or large configuration changes. The most common photochemical processes involved in photoswiches actioning include Z/E isomerization, ring opening/closing, and excited state proton or hydrogen transfer. The photoswitching action may results in the strong change of the physico-chemical properties of the switch itself and its coupling with the environment, hence they can be used to enforce information storage, coding, and transduction. As a most paradigmatic example, the photoinduced Z/E isomerization of retinal inside rhodopsin constitute the first event triggering the complex cascade leading to vision in superior animals. Photoswitches have also been largely exploited to obtain smart materials, whose mechanical and structural properties can be tuned by light stimuli, molecular machines, or drug delivering agents. From a photochemical point of view, photoswitching usually requires that the excited state potential energy surface (PES) evolves towards non-adiabatic point, i.e. crossing between the ground and the different excited states such as conical intersections (CI). The photochemical quantum yield of switching will be largely dependent on the topology of the CI and on the geometrical deformation needed to access these non-adiabatic points.