Ruthenium sensitizers RuL3 (yellow) cis-RuL2(NCS)2 (red) and RuL'(NCS)3 (green)
where L = 2,2'-bipyridyl-4,4'-dicarboxylic acid and L' = 2,2',2''-terpyridyl-4,4',4''-tricarboxylic acid.
The lower part of the picture shows nanocrystalline TiO2 films loaded with the respective sensitizer.