The field of supramolecular catalysis has been traditionally inspired by Nature, and as such many enzyme mimics have been reported. These generally consist of a catalyst in a cage, or a catalyst with a binding site. However, enzymes are generally far more sophisticated and as a result the current supramolecular systems generally fail to achieve the typical catalyst properties displayed by enzymes. In this proposal we aim to generate more sophisticated enzyme mimics and devices based thereon using strategies to build a peptide-like second coordination sphere around an active site. We have chosen to apply this approach for the development of hydrogenase mimics, as there is a large gap between the properties of the current functional synthetic mimics and the actual metalloenzyme. Next to that, proton reduction catalysis to afford renewable dihydrogen (H2) is important in the context of green energy as the efficient production and usage of this chemical fuel is intimately linked to the development of solar to fuel devices. As such, part of the project is oriented to integration of these synthetic mimics into longevous electrode materials. During this project we will develop strategies to place well-defined Fe2S2 hydrogenase mimics inside M12L24 nanospheres that are internally decorated with functionalized peptide chains. This will allow us to study exactly how the peptide environment has an influence on crucial catalyst properties such as rate and overpotential at which the mimic starts to produce hydrogen. The spheres will also be combined with light-harvesting components for light driven proton reduction. Detailed photophysical studies will unravel relate important parameters such as charge separation and recombination, to the efficiencies of photocatalysis. In a related strategy, the polypeptides and hydrogenase mimics will be brought together using MOF synthesis, which allows the generation of novel functional devices.