Fast response and high sensitivity europium metal organic framework fluorescent probe with chelating terpyridine sites for Fe³⁺.

Iron is one of the most important elements in the metabolic process for all living system. However, both its deficiency and excess from normal permissible limits can induce serious disorders. We synthesized a europium-based metal-organic framework (Eu-MOF), EuL(3) (L = 4'-(4-carboxyphenyl)-2,2': 6',2″-terpyridine), under hydrothermal conditions, and used it as a solid luminescence sensor for Fe(3+) ions. The robust EuL(3) shows fast response (∼ 1 min) and high sensitivity (Stern-Volmer constant K(SV) = 4.1 × 10(3) L/mol) for Fe(3+) ions in aqueous solution or biological systems due to the existence of chelating terpyridine and open channels. The simple and portable test paper based on the EuL(3) fluorescent sensor system provides a convenient and reliable detection of Fe(3+) in every day applications. This pioneering work contributes to extend the potential application of Ln-MOFs to the biological and environmental areas.