Dual-Color Visual Ratiometric Fluorescence Sensing for H₂O and D₂O Mixtures Using a Hexanuclear Ln(III) Cluster-Based Metal–Organic Framework

Abstract

High-purity heavy water (D 2 O) is a strategic material owing to its important application in the fields of nuclear energy and scientific research. D 2 O always tends to get contaminated by H 2 O owing to its strong hygroscopicity. Herein, a bimetallic hexanuclear Ln(III) cluster-based metal−organic framework (Eu 0.5 Tb 0.5 -TZB-MOF) has been synthesized for fluorescence sensing of the D 2 O−H 2 O binary mixtures. Eu 0.5 Tb 0.5 -TZB-MOF can be used to immediately differentiate D 2 O or H 2 O via fluorescent color responses that are obvious to the naked eye and allow for quantitative ratiometric analysis using simple spectrophotometry. Fluorescence titration experiments demonstrate that both trace H 2 O in D 2 O and trace D 2 O in H 2 O can be quantitatively detected. Mechanistic studies demonstrate that the weaker vibrational quenching of the O−D oscillator compared to the O−H oscillator, in addition to the terbium-to-europium energy transfer, triggered the fluorescence signal response.

Immobilization of europium and terbium ions with tunable ratios on a dispersible two-dimensional metal–organic framework for ratiometric photoluminescence detection of D2O

“…, 1.1 wt% and 1.8 wt%, for Eu-Tb-ZrBTB(1 : 10) and Eu-ZrBTB, respectively. With these LOD values, Eu-Tb-ZrBTB(1 : 10) and Eu-ZrBTB were also compared with other lanthanide-based materials reported for D 2 O detection, 53,54,72 as summarized in Table S3 †…”