Ultrafast kinetics of supramolecules with a Ru(II)- or Os(II)-polypyridyl light absorber, cis-Rh(III)Cl2-polypyridyl electron collector, and 2,3-bis(2-pyridyl)pyrazine bridge

A series of photoexcited mixed-metal supramolecules are shown to undergo electron transfer from a metal-to-ligand charge transfer state (MLCT) to generate a metal-to-metal charge transfer state (MMCT) in ∼7 ps. Unlike the MLCT/MMCT free energy difference, the MMCT/ground state energy varies in the series, thus relaxation times span ∼20 ps to ∼30 ns.61