“…Guided by the fact that the ancillary ligand should provide strong binding of the dye to the semiconductor surface, which is usually achieved by the incorporation of anchoring carboxy-group(s) into the ligand, and simultaneously aiming at decreasing the Ir 4+ /Ir 3+ redox potential, we have synthesized new aromatic β-diketones containing a carboxymethyl group and donating thiophene or 4-piperydylphenyl moieties, which shift the unoccupied orbital localization towards the anchoring functionality. 11,38 Such 1,3-diketones are readily available via soft acylation 39 that allows for introducing various functional fragments into the aromatic rings of the 1,3-diketones making the electronic and structural properties of the ligands more tunable. 40 The ester group of the already coordinated 1,3-diketonate can be easily hydrolyzed producing the corresponding complex iridium( iii ) salt, which is suitable for sensitization of titania photoanodes.…”