Highly Stable MOF-76(Sm) Luminescence Sensor for Efficient Identification of D2O and H2O

Abstract

Heavy water (D₂O) is an essential solvent with extensive applications, notably as a neutron moderator in nuclear reactors, and plays a vital role in the fields of nuclear energy production and chemical analysis. Nevertheless, the strong interaction between H₂O and D₂O leads to the pronounced hygroscopic nature of D₂O, and the significant similarities in their physical and chemical properties further complicate the distinction between these two substances. Consequently, it is imperative to develop a methodology for the detection of D₂O content in H₂O. In this work, we synthesized a water-stable MOF-76(Sm) luminescent sensor with lanthanide metal Sm and 1,3,5-benzenetricarboxylate anion. The Sm³⁺ ions in the MOF-76(Sm) can be effectively sensitized by the ligand and show a good luminescence response to the D₂O–H₂O system. Compared with the O–H bond of water, MOF-76(Sm) has a smaller vibration quenching of Sm³⁺ ions by the O–D bond of heavy water, which leads to the enhancement of the luminescence of D₂O, and realizes the quantitative detection of D₂O content in H₂O. A series of experiments have demonstrated that this sensing material exhibits a robust fluorescence response across the entire range of the D₂O–H₂O system, enabling the quantitative detection of D₂O in H₂O. Furthermore, the material can be recycled and reused, underscoring its practical application value. The MOF-76(Sm) is expected to function as a precise, sensitive, and comprehensive quantitative instrument for evaluating the D₂O content in water systems, all while ensuring its recyclability. This study offers empirical support for the advancement and utilization of the lanthanide element samarium, as well as for the broader application of current metal-organic framework (MOF) materials.