Color-tunable hypersensitive temperature sensor based on metal organic framework doped with Eu3+ and Dy3+ via phonon-assisted energy transfer

In this work, catena-[(μ-benzene-1,3,5-tricarboxylato)-(1,10-phenanthroline)-( N , N -dimethylformamide)-gadolinium(iii)- N,N -dimethylformamide solvate] (denoted as Gd-MOF) co-doped with Eu 3+ and Dy 3+ was successfully synthesized. The entire X-ray diffraction peaks of the sample match well with the Gd-MOF phase. A detailed characterization by inductively coupled plasma mass spectrometry (ICP-MS) shows that the actual concentration is basically consistent with the design concentration. The temperature sensing properties of Gd-MOF:Eu 3+ ,Dy 3+ were analyzed by temperature-dependent fluorescence spectra from 213 to 453 K. As temperature rises, the emission color of Gd-MOF:Eu 3+ ,Dy 3+ changes from yellow to red. The relative sensitivity reaches a maximum of 5.87%/K at 383 K in the Gd-MOF:1%Eu 3+ ,30%Dy 3+ sample. The high relative sensitivity of this MOF is due to the phonon-assisted energy transfer from Dy 3+ to Eu 3+ , which is proved via fluorescence decay curves and fluorescence spectra. The major route of this energy transfer is 4 F 9/2 (Dy 3+ ) → 5 D 1 (Eu 3+ ).