Facile preparation of codoped lanthanide metal–organic frameworks with efficient energy transfer for ratiometric temperature sensing.

A series of Ln-MOFs 1–3 and codoped Ln-MOFs [[(CH₃)₂NH₂][Eu_2xTb_2(1-x)(HL)(H₂O)₇]·2H₂O [x = 0.01 (4), 0.015 (5), 0.03 (6), 0.07 (7), 0.11 (8), 0.14 (9), 0.17 (10), 0.21 (11), 0.26 (12), 0.30 (13), 0.50 (14), 0.75 (15)] were synthesized. Isostructural Ln-MOFs display 2D Layers. Chemical compositions of Ln-MOFs were characterized by plasma mass spectrometry, X-ray photoelectron spectra, transmission electron microscopy and energy-dispersive X-ray spectroscopy elemental mapping. Remarkably, the luminescent color of codoped Ln-MOFs 4–15 can be gradually controlled and tunable emission colors with corresponding CIE coordinates gradually change from (0.3787, 0.5623) to (0.541, 0.399). A meticulous theoretical investigation of the Tb³⁺-to-Eu³⁺ energy transfer in codoped Ln-MOFs is also performed and calculated efficiency from Tb³⁺ to Eu³⁺ can exceed 49%. Furthermore, codoped Ln-MOF 9 allows for the design of a ratiometric luminescent thermometer with function of T = −721.36654I_Tb/I_Eu + 793.34658 over a wide range of 80 to 280 K. A series of codoped Ln-MOFs assembled by octacarboxylate-based resorcin[4]arene ligands were synthesized and characterized, where codoped Ln-MOF 9 allows for the design of a ratiometric luminescent thermometer over a wide range of 80 to 280 K. [ABSTRACT FROM AUTHOR]