Molecular systems exhibiting intramolecular proton transfer in the excited electronic state from one distinct ground-state proton station to another are investigated in a joint collaborative research thrust by ultrafast spectroscopy, theoretical simulations and organic synthesis. The proposed project aims to establish a new class of photochromic, bidirectional molecular proton transfer switches with superior properties and to gain detailed experimental and theoretical insight into their ultrafast dynamics. A long-term goal is an extension towards proton transport across several stations, opening vast potential for a multitude of interesting applications.