Photoinduced electron-transfer (PET) processes in molecular assemblies combining phenothiazine (PTZ) or π-extended tetrathiafulvalene (exTTF) donors (D), Ru(II) bisterpyridine photosensitizers (P) and polyoxometalate (POM) acceptors (A) have been studied. For this purpose, molecular dyads (i.e., D–P) were prepared by the functionalization of terpyridine-based ligands with the PTZ and exTTF donor units and subsequent ruthenium coordination to obtain heteroleptic, bisterpyridine complexes. In addition, the complexes are equipped with a terminal alkyne group, which was used for the linkage with a Keggin-type POM. In this regard, molecular triads (i.e., D–P–A) were prepared by a Sonogashira cross-coupling of the positively charged Ru(II) complex and the negatively charged POM. Electrochemical and photophysical studies were performed and revealed a significant quenching of the Ru(II)-based emission with increasing donor strength, which suggested an intramolecular electron transfer from the donor chromophore to the Ru(II) site and the formation of charge-separated states (CSS). The introduction of the POM framework revealed no further quenching of the emission, this was tentatively ascribed to a minor influence of the electron acceptor on the excited states of the Ru(II) complexes.

Molecular dyads and triads comprising phenothiazine or exTTF donors, Ru(II) bisterpyridine complexes and polyoxometalates

254th National Meeting (2017)

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