Used as a building block in metal-organic frameworks (MOFs) for gas storage and separation due to its rigid aromatic structure and strong binding sites. Acts as a chelating agent in catalysis and stabilizes metal ions in aqueous systems. Employed in surface modification of metal oxides for corrosion protection and functional coatings. Also explored in proton-conducting membranes for fuel cell applications because of its ability to retain phosphonic acid groups that facilitate proton transport.