Terbium(III) based coordination polymer microparticles as a luminescent probe for ascorbic acid

We report on terbium coordination polymer (Tb-CP) microparticles prepared from Tb(III) ion, dipicolinic acid (DPA; acting as a bridging ligand) and tris(hydroxymethyl)aminomethane (Tris; acting as an auxiliary ligand), and show that it can be used as a luminescent probe for ascorbate in aqueous solutions. The Tb-CP emits strong fluorescence due to an intramolecular energy transfer from DPA to the Tb (III) ion, and both fluorescence intensity and decay time are quenched by ascorbate. This finding led to a method for the quantitation of ascorbic acid in the 1 μM to 1 mM concentration range and with a detection limit at ∼200 nM. The strategy presented here is based on the construction of special functions directly from initial molecule/ion blocks and is expected to enable the design of various other CP materials for use as optical probes. (author)