Highly Facile Strategy for Detecting D₂O in H₂O by Porphyrin-Based Luminescent Probes

Owing to their almost similarities in size, shape, and chemical reactivity, effectively distinguishing deuteroxide (D₂O) in water (H₂O) remains an ongoing challenge, and the examples of a D₂O probe are still quite scarce. Herein, since H₂O can decrease the lifetime of a singlet oxygen as a vital intermediate and an H/D exchange in the luminescence process of porphyrins, we systematically investigated the enhanced ultraviolet–visible (UV–vis), photoluminescence (PL), and electrochemiluminescence (ECL) of water-soluble tetrakis­(carboxphenyl)­porphyrin (TCPP) in D₂O. The findings showed that these luminescent properties had been greatly enhanced with the increase of the D₂O fraction in water. Consequently, we first developed the highly facile methods of detecting D₂O in H₂O by the UV–vis, PL, and ECL of TCPP, respectively. Impressively, the ECL analysis exhibited a great superiority with a lower detection limit of 0.29 nM. The work not only achieves the challenging task of distinguishing between H₂O and D₂O but also provides a unique strategy to enhance the luminescent performance of porphyrin.