Photophysical properties of a dinuclear rack-type Ru(II) complex and of its components

The luminescence spectra and lifetimes (at room temperature and 77 K) and triplet-triplet transient absorption spectrum (at room temperature) of a rack-type complex (4) made of two Ru(II) ions, a bridging ligand (3) containing a bis-(bipyridyl)pyrimidine subunit (2) covalently linked to an anthracene moiety (1) and two 2,2′:6′,2″-terpyridine ligands have been investigated. Comparison with the luminescence properties and transient absorption spectra of the 1, 2, and 3 subunits shows that in the supramolecular species 4 excitation energy flows with unitary efficiency to the lowest excited state, which is a triplet Ru → 3CT level, regardless of which chromophoric subunit is excited.