(2-Hydroxyphenyl)diphenylphosphine is an organophosphorus compound featuring a phenolic hydroxyl group and a diphenylphosphine moiety. This bifunctional structure makes it a versatile ligand precursor and synthetic building block. Its primary application is in the field of materials chemistry, particularly as a ligand for the synthesis of luminescent metal complexes. It is widely used to prepare cyclometalated iridium(III) and platinum(II) complexes, which are key components in organic light-emitting diodes (OLEDs) and other photoelectronic devices. The phenolic oxygen and phosphorus donor atoms allow for stable chelation to transition metals, tuning the photophysical properties of the resulting complexes. As an organic synthesis building block, the compound serves as a precursor for phosphine ligands and can participate in various metal-catalyzed coupling reactions. Its reactivity stems from both the nucleophilic phosphine group and the acidic phenolic proton.