Highly pH-Stable Ln-MOFs as Sensitive and Recyclable Multifunctional Materials: Luminescent Probe, Tunable Luminescent, and Photocatalytic Performance

Reasonably designing highly pH-stable lanthanide metal–organic frameworks (Ln-MOFs) is of great importance for multifunctional applications. Herein, three isostructural Ln-MOFs, namely, {[Ln(tcmb)(H2O)2]·2H2O}n (1-Ln, where Ln = Eu, Tb, Gd), have been synthesized and characterized. Experiments results showed that 1-Tb displayed high thermal, pH, and luminescence stability, which provided the possibility for its practical application. Because of the excellent luminescence performances of Ln-MOFs, the luminescent sensing and photocatalytic properties were investigated. 1-Tb exhibits high sensitivity, selectivity for sensing Fe3+, CrO42–/Cr2O72– ions in the presence of other competition ions. In addition, 1-Gd demonstrates the high photocatalytic activity for degrading tetracycline (TC) under visible light, with the degradation efficiency achieving 82% approximately. To prepare multicolor luminescence materials, by adjusting the relative proportion of Eu3+ and Tb3+ we constructed bimetallic Ln-MOFs 1-EuxTb1–x with excellent linear color tunability from green to red, suggesting that 1-EuxTb1–x can be the candidates for optical imaging and barcode research.