Molecular switches may also find most valuable applications in the field of light-activated therapies (LAT), especially against cancer. The main goal of photopharmacology is to improve selective cancer cells targeting in order to increase efficacy and reduce sides effect of conventional chemotherapeutics. One of the most widespread strategy is photodynamic therapy (PDT), in which malignant cells are destroyed by the photo-activated production of reactive oxygen species and in particular singlet oxygen ( 1 O 2 ),. In this framework, photoswitches may contribute to bypass one inherent problem of PDT namely the necessity to rely on the activation of O 2 , which can be problematic due to the hypoxic conditions found in some solid tumors. A different strategy may rely on the accumulation of the molecular switch into the cellular lipid membrane, followed by its light-induced conformational change, which results in the membrane destabilization and permeabilization hence triggering cell death. To apply this strategy, however, it is necessary that the chemical properties of the switch permit the formation of stable and persistent aggregate with the biological macrostructure, a condition which can be met by the inclusion of hydrophobic groups to facilitate the penetration in the lipid core. On the other hand, the two form of the switches should possess different interaction patterns with the biological membrane to assure that the lightinduced perturbation will be transferred as a strong perturbation of the macrostructure. The photoisomerization of double bonds, which is generally accompanied by large changes in space-occupation and steric hindrance, appears as the most promising event to build efficient membraneperturbing switches.