Molecular Dyads and Triads Based on Phenothiazine and π‐Extended Tetrathiafulvalene Donors, Bis(terpyridine)ruthenium(II) Complexes, and Polyoxometalates

Molecular dyads were prepared by the functionalization of organic electron‐donor units, that is, a phenothiazine (PTZ) moiety and a π‐extended tetrathiafulvalene (exTTF) moiety, with bis(terpyridine)Ru II complexes. In addition, the complexes were equipped with a terminal alkyne group, which was used for the coupling with a Keggin‐type polyoxometalate (POM). In this regard, molecular triads were prepared, whereby the central Ru II complex should act as a photosensitizer and the POM as an electron acceptor. Certain spectral changes were observed upon attachment of the donors and the POM framework to the Ru II complexes. In particular, the emission of the Ru II complex became significantly reduced with increasing donor strength, which suggested an intramolecular electron transfer by reductive emission quenching. The introduction of the POM framework revealed no further quenching of the emission and is tentatively ascribed to the minor influence of the electron acceptor on the excited states of the Ru II complex.