Ratiometric visualization fluorescence temperature sensing based on dual-lanthanide metal-organic frameworks

High-performance optical temperature sensors play an important role in various fields, and lanthanide metal-organic frameworks (Ln-MOFs) are expected to be luminescent temperature sensors due to their distinctive luminescent properties. Herein, a new three-dimensional (3D) Ln-MOF [Tb(TCA)(Phen)]·DEF (1) (H3TCA = 4,4′,4′'-nitrilotribenzoic acid, Phen = 1,10-phenanthroline, DEF= N, N-diethylformamide) is constructed with a rtl topology based on {Tb2(COO)4} secondary building units (SBUs). Meanwhile, dual-lanthanide Ln-MOFs [TbxEu1-x(TCA)(Phen)]·DEF (2-6) are also synthesized by varying the ratio of Tb3+: Eu3+ in the reaction mixture, which can be applied in practical LED applications originating from their visual luminescent color changes. Among them, 4 is an efficient ratiometric fluorescent thermometer over a wide temperature range from 283 to 393 K and has a large relative sensitivity Sr of 4.2407% K−1 at 393 K with good repeatability. Furthermore, the emission color of 4 gradually changes from yellow (283 K) to orange-red (393 K) as temperature increases for visual colorimetric temperature measurements, which attributed to the energy transfer between Tb3+ and Eu3+ ions.