Terpyridine-based complex nanofibers with Eu³⁺ as a highly selective chemical probes for UO₂²

Uranyl is a radioactive, toxic pollutant commonly found in the waste remaining after nuclear fuel reprocessing, and it poses several types of risks to human health; therefore, developing absorbents and chemical probes for this compound is crucial to overcoming these issues. This study examined the sensing abilities of terpyridine-appended benzenetricarboxyamide (T-BTA) as a chromogenic probe for detecting uranyl ions (UO₂²⁺). The complex with Eu³⁺ (1-Eu) spontaneously formed nanostructured fibers in H₂O owing to the triamide groups of T-BTA, which induced intermolecular hydrogen-bonding interactions. The strong blue emission of these nanofibers in H₂O was quenched upon adding UO₂²⁺ but not upon adding any other metal ion. This high selectivity was probably because of the interactions between the nitrigen atoms of the terpyridine moieties of 1 and UO₂²⁺. Furthermore, the 1-Eu nanofibers assumed spherical morphologies when UO₂²⁺ was added. To develop a convenient UO₂²⁺ sensor, an electrospun film incorporating 1-Eu (ESF-1-Eu) was manufactured, and it exhibited high selectivity for UO₂²⁺ over a variety of rival metal ions. The plot for luminescence change of ESF-1-Eu vs UO₂²⁺ concentrations in seawater samples showed a good linearty. Thus, the ESF-1-Eu shows potential as a useful sensor for detecting and removing UO₂²⁺ in H₂O.