Anions are typically too hydrophilic to freely pass through biological membranes. This also applies to those drugs that are anionic at physiological pH. Synthetic anion transporters, i.e. small, lipophilic molecules that facilitate diffusion of anions across lipophilic barriers, may accelerate the diffusion of anionic drugs by many orders of magnitude and thus could dramatically increase their effectiveness. Moreover, transporters whose activity could be controlled by light, pH or other stimuli could enable the targeted delivery of drugs to the desired place and at the right time. The aim of this project is to develop the first switchable transporters for anionic drugs, and hence to demonstrate a new strategy for targeted drug delivery. As part of it, we will undertake research on the construction of transporters switchable by changes in pH or irradiation with light of a specific wavelength. We hope that this research will lead to the development of a new strategy for smart drug delivery, which may find practical applications in the future, e.g. in the treatment of cancer.