Photoactivity of Covalently Linked Noble Metal-Free Cu(I)-Photosensitizer-Polyoxometalate Dyads

Covalent photosensitizer-polyoxometalate dyads are promising systems to combine light-harvesting and charge-storage within one molecular compound. Here, we report the synthesis and photophysical characterization of two noble-metal-free photosensitizer–polyoxometalate (PS–POM) dyads based on heteroleptic Cu(I) diimine/biphosphine complexes covalently linked to Dawson-type polyoxotungstates. The dyads were assembled via phosphonate anchoring of functionalized phenanthroline ligands, followed by Cu(I) coordination. Time-resolved spectroscopy reveals rapid visible-light-induced electron transfer from the Cu(I) photosensitizer to the POM, generating a short-lived charge-separated state with sub-nanosecond recombination. These results demonstrate the feasibility of Cu(I)-based PS–POM dyads and provide design principles for noble-metal-free photoactive assemblies.