Two-dimensional Cd(ii) coordination polymer encapsulated by Tb(3+) as a reversible luminescent probe for Fe(3+)

A two-dimensional luminescent cadmium(ii) coordination polymer, [Cd(modbc)(2)](n) (Cd-P); modbc = 2-methyl-6-oxygen-1,6-dihydro-3,4′-bipyridine-5-carbonitrile, was successfully synthesized by a solvothermal reaction and fully characterized. Cd-P exhibited excellent luminescence emission, and detected Cu(2+), Co(2+), Fe(2+), Hg(2+), Ni(2+) and Fe(3+) ions with high sensitivity and showed good anti-interference performance. After encapsulation of Tb(3+) ions in Cd-P, the as-obtained fluorescent functionalized Tb(3+)@Cd-P maintained distinct chemical stabilities in different pHs and metal salt solutions. Subsequently, we explored the potential application of Tb(3+)@Cd-P as a probe for Fe(3+) ions. A new and convenient method for individual identification of Fe(3+) ions by the combination of Cd-P and Tb(3+)@Cd-P was successfully established. A possible sensing mechanism is discussed in detail.