Synthesis of Amphiphilic Ru-II Heteroleptic Complexes Based on Benzo[1,2-b:4,5-b]dithiophene: Relevance of the Half-Sandwich Complex Intermediate and Solvent Compatibility

The detailed synthesis and characterization of four ruthenium(II) complexes [RuLL(NCS)(2)] is reported, in which L represents a 2,2-bipyridine ligand functionalized at the 4,4 positions with benzo[1,2-b:4,5-b]dithiophene derivatives (BDT) and L is 2,2-bipyridine-4,4-dicarboxylic acid unit (dcbpy) (NCS=isothiocyanate). The reaction conditions were adapted and optimized for the preparation of these amphiphilic complexes with a strong lipophilic character. The photovoltaic performances of these complexes were tested in TiO2 dye-sensitized solar cell (DSSC) achieving efficiencies in the range of 3-4.5% under simulated one sun illumination (AM1.5G).