Energy transfer mediated by asymmetric hydrogen-bonded interfaces

Abstract

Amidine-appended ferrocene derivatives form a supramolecular assembly with Ru(II)(bpy-COOH)(L)₂²⁺ complexes (bpy-COOH is 4-CO₂H-4′-CH₃-bpy and L = bpy, 2,2′-bipyridine or btfmbpy, 4,4′-bis(trifluoromethyl)-2,2′-bipyridine). Steady-state, time-resolved spectroscopy and kinetic isotope effects establish that the metal-to-ligand charge transfer excited states of the Ru(II) complexes are quenched by proton-coupled energy transfer (PCEnT). These results show that proton motion can be effective in mediating not only electron transfer (ET) but energy transfer (EnT) as well.