Our research goal is to transfer external stimuli into functionality on the molecular level. We focus on controlling intermolecular interactions in host-guest systems such as Metal-Organic Frameworks and at hybrid interfaces by light. Combining multiscale simulations with experimental methods (e.g. time-resolved vibrational spectroscopy and scanning probe techniques), we investigate dynamic phenomena ranging from directed molecular motion to electron transfer processes and self-assembly mechanisms in well-defined molecular environments. Using this approach we study in particular the dynamics of photo-responsive molecular units with an emphasis on molecular machines. By correlating the dynamic phenomena on the molecular level with the resulting functionality of the molecular systems (e.g. photo-catalysis or selective drug release), we aim to derive new concepts for the development of smart stimuli-responsive nanomaterials.