Using light to induce energy and electron transfer or molecular motions in multicomponent systems

Light-induced processes are at the basis of fundamental natural phenomena as well as of a variety of applications. Since the functions that can arise from the interaction between light and matter depend on the degree of complexity and organization of the receiving 'matter', the research on these processes has progressively moved from molecular to supramolecular (multicomponent) systems, thereby originating the field of supramolecular photochemistry. In this context, examples of photochemical molecular devices and machines--that is, multicomponent chemical systems capable to perform specific functions under light stimulation--have been developed. Here we report examples of molecular devices in solution, where light is employed (i) to create and transport electronic energy, (ii) to displace electrons, and (iii) to set molecular components in motion, mimicking the operation of mechanical machines and motors. These studies are of interest not only for increasing the basic understanding and testing of current theoretical treatments of photoinduced processes but also eventually for the growth of nanoscience.