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.