Hypersensitive ratiometric temperature sensing in a bimetallic lanthanide metal–organic framework

Abstract

Ratiometric luminescent temperature sensing based on a single matrix is highly desirable at present. However, the adjustments of the temperature response range and sensitivity are still a huge challenge. Herein, a novel series of isostructural three-dimensional (3D) lanthanide metal–organic frameworks (Ln-MOFs) {[Ln₄(ebdc)₆(DMF)_2.75(H₂O)₇]}_n (HPU-99, where Ln = Eu and Eu_xTb_1−x, H₂ebdc = 5-ethynyl-isophthalic acid) are synthesized by a solvothermal method using a 5-ethynyl-isophthalic acid ligand (H₂ebdc). Notably, a series of Ln-MOFs Eu_xTb_1−x-HPU-99 (x = 0.05, 0.1, 0.2) are obtained by adjusting the proportion of Eu³⁺/Tb³⁺ in the bimetallic materials, which exhibit temperature dependent luminescent behavior with a fluorescence color gradient and demonstrate that chemical components would affect the ratiometric luminescent temperature sensing performance. Furthermore, the luminescence of HPU-99 is altered after the argentophilic alkynyl groups anchor the silver nanoclusters (Ag NCs). This work showcases that bimetallic Ln-MOFs have great potential in luminescent sensing at an atomically precise level.