Complexes, obtained by mixing anchoring groups like H2dcbpy (H2dcbpy = 4,4'-dicarboxy-2,2'-bipyridine) as well as an electron donating and/or protective groups held on the second bipyridine and a ruthenium photoactive centre (whose properties are intimately related to surrounding ligands), opened the field of dye molecular engineering on TiO2. Alkyl chains have been introduced and opened the generation of amphiphilic heteroleptic ruthenium polypyridyl photosensitisers. The presence of hydrophobic chains afforded a strong improvement in the stability of solar cells performances emerging probably from preventing dye desorption.

In a previous study FTIR data showed unambiguously that such heteroleptic complexes are chemisorbed on TiO2 surface in bidentate chelation mode using two carboxylate groups rather than forming an ester type linkage.
The nanocrystalline TiO2 (anatase) films were prepared on conducting glass using a previously described procedure. The electrodes were heated up to 450°C and then allowed to cool down before dipping into a dye solution for 20 hours. The dark red coloured films were tested in photovoltaïc cells with a redox electrolyte composed by 0.6 M butylmethylimidazolium, 50 mM iodine, 500 mM t-butylpyridine and 100 mM lithium iodide in a 1 to 1 solvent mixture of acetonitrile-valeronitrile.