Used as a key building block in metal-organic frameworks (MOFs) for gas storage and separation due to its rigid aromatic structure and dual phosphonic acid groups that strongly coordinate with metal ions. Employed in proton-conducting membranes for fuel cells, where the phosphonic acid moieties facilitate proton transport under low-humidity conditions. Also applied in surface modification of metal oxides for corrosion protection and as a linker in hybrid materials for catalysis and sensing applications.