Anchoring group and auxiliary ligand effects on the binding of ruthenium complexes to nanocrystalline TiO₂ photoelectrodes

An investigation of five ruthenium complexes with the thermodynamics and kinetics of binding to nanocrystalline TiO₂ was made. The ruthenium complexes were structurally different in the number of anchoring carboxy groups attached to coordinated bipyridyl ligands and in the number of auxillary ligands. All the available carboxyl groups were used by the complexes in the dry state with only one monocarboxy or dicarboxy ligand to bind to the surface. The structural difference between the complexes in the five dyes yielded similar maximum coverages ( >100nmol cm^-2) on nanocrystalline TiO₂ electrodes and exhibited different binding constants.