Luminescence quenching of the excited tris-bipyridyl ruthenium(II) ion by copper(II)-cyclodextrin complexes

The quenching of the luminescence intensity and lifetime of the electronically excited species Ru(bipy)₃²⁺ by a series of copper (II) cyclodextrin complexes is studied. It is found that conventional Stern-Volmer behaviour is not followed. A modified version of the Stern-Volmer equation, one which assumes purely static quenching, is in good agreement with experimental data. Inclusion of the Ru(bipy)₃²⁺ by the metallo-cyclodextrin complex is observed to play a key role in the quenching mechanism.