2-(2,4-Difluorophenyl)-5-methylpyridine (DFPMPy), CAS number 583052-21-5, is a difluorinated heterocyclic derivative of arylpyridine with enhanced solubility by the methyl group. DFPMPy is often used as a cyclometalating ligand with the nitrogen electron lone pair and the delocalized π-electron cloud in the benzene ring being coordinated to a metal center. The metal-ligand complexes have demonstrated excellent photocatalytic capability in visible-light photoredox reactions. During the photoredox process, an electron migrates from the metal center to the ligands, also known as metal-ligand charge transfer (MLCT) after irradiation as the complex reaches the excited state. After the single-electron transfer, the excited complex regains an electron from another reagent and restart the photoredox catalytic cycle.
These complexes are also synthesized for light-emitting electrochemical cells with photoluminescent quantum yield up to 93%. The fluorine-substituents lower the highest occupied molecular orbital (HOMO) energy level resulting shifts in the emission spectrum. Arylpyridine-iridium complexes are widely investigated in water splitting to generate hydrogen. As photosensitizers, these complexes are also used in dye-sensitized solar cells (DSSCs).