Supramolecular systems combine molecular-level control of structure and reactivity with the ability to deploy a range of specific intermolecular interactions to access new function. These concepts have led to groundbreaking developments ranging from supramolecular surface patterning to molecular machines 2 and stimuli-responsive nanostructures. In the field of catalysis, supramolecular concepts have been developed to tune reactivity, selectivity as well as in-situ catalyst assembly, highlighting the enormous potential of this field of research. Over the last decade, pioneering studies have demonstrated the potential of supramolecular catalysis for energy conversion and storage, e.g. in the fields of water oxidation, CO2 reduction, and the hydrogen evolution reaction (HER). In light-driven HER catalysis, pioneering studies have demonstrated how supramolecular systems can be accessed by combining molecular catalysts with molecular photosensitizers. Often, component interactions are controlled by electrostatics, hydrogen bonding or -stacking. The design of molecular platforms is a central concept in supramolecular energy conversion, including HER, as it enables the merging of several functions in one molecule. Socalled photochemical dyads utilize these concepts to combine photosensitizer, charge-transfer system and HER catalyst in one (supra)molecular assembly. Figure : Left: Schematic illustration of the supramolecular photochemical system for visible light-driven hydrogen evolution. An anionic POM-platform molecule is covalently functionalized with a molecular Pt-HER catalyst. The system is electrostatically coupled to a cationic photosensitizer (PS). SED -sacrificial electron-donor. Right: molecular structure of the POM-PtX-platform (X = Cl, I, shown here: X = I, for crystallographic data see SI).