Luminescent Nanothermometers Obtained by Post‐Synthetic Modification of Metal‐Organic Framework MIL‐68

Abstract

Metal‐organic frameworks (MOFs) bearing lanthanide ions are excellent platforms for designing luminescent thermometers. However, so far, post‐synthetic modification of MOFs linkers has not been explored as a route to produce such thermometers, despite its potential to design the lanthanide coordination sphere and, thus, tune the emission properties of the material. Here, nanocrystals of MIL‐68‐NH2 were post‐synthetically modified via a cross‐linking reaction with 1,4‐Bis{4‐[(E)‐3‐(N,N‐dimethylamino)prop‐2‐enoyl]phenoxy}butane (HL), followed by coordination to Eu3+ and Tb3+ ions. The luminescence properties of the material were assessed. Tb90Eu10‐MIL‐68‐HL was found to be an excellent cryogenic (< 100 K) ratiometric luminescent nanothermometer exhibiting a maximum relative sensitivity of 9.4 % K–1 at 12 K.

Dual Emission in a Ligand and Metal Co-Doped Lanthanide-Organic Framework: Color Tuning and Temperature Dependent Luminescence

“…The maximum value of the relative sensitivity S m = 2.51 %K −1 is obtained at 80 K. These results indicate that 7 can function as a ratiometric luminescence thermometer in the tested region from 80 to 300 K showing its best performance in the 80 to 150 K region. The maximum relative sensitivity of 2.51 %K −1 shown by 7 compares well with the typical values obtained with many luminescent thermometers based on lanthanide organic frameworks [8][9][10]43]. Therefore, combined ligand and metal doping can be an effective route for the preparation of improved luminescent temperature sensors.…”

“…Recently, a considerable amount of research effort has been directed towards the development of lanthanide ratiometric thermometers [6] which are based on the temperature-induced changes in the photophysical behavior of at least two emission centers, thereby providing a more reliable and accurate self-referenced signal with reduced dependence on the experimental conditions. The majority lanthanide luminescent thermometers reported in the literature are based on measuring the ratio between the emission intensities of Tb 3+ and Eu 3+ centers at different temperatures [7][8][9][10] while those that involve the emission of a bridging ligand [11] or an encapsulated organic dye [12] are relatively rare.…”

Microwave-assisted synthesis to prepare metal-organic framework for luminescence thermometry

“…Indeed, in the literature, many cryogenic luminescent thermometers based on mixed Eu-Tb MOFs exhibits a chain topology of the inorganic network. [35][36][37] Thus, the distance Ln-Ln is very short favoring the occurrence of energy transfer between two Ln 3+ or energy migration.…”

Tuning of Thermometric Performances of Mixed Eu–Tb Metal–Organic Frameworks through Single‐Crystal Coordinating Solvent Exchange Reactions

“…However, this field is still in its infancy and many progresses are still necessary to reach maturity. The literature in this area, thus, includes only two studies involving a PSM that led to the turn‐on of the photoluminescence and the temperature sensing capability of a non‐luminescent pristine material [ 29 ] and the investigation of the thermometric performances of an Eu 3+ ‐based MOF and its guest, as well as the guest and coordinated solvent molecule exchanged analogs. [ 30 ]…”

“…However, this field is still in its infancy and many progresses are still necessary to reach maturity. The literature in this area, thus, includes only two studies involving a PSM that led to the turn-on of the photoluminescence and the temperature sensing capability of a non-luminescent pristine material [29] and the investigation of the thermometric performances of an Eu 3+ -based MOF and its guest, as well as the guest and coordinated solvent molecule exchanged analogs. [30] Herein, we discuss the thermometric properties of the rigid MOF [Tb 1.9 Eu 0.1 (N-BDC) 3 (DMF) 4 ] (EuTb-NBDC) (N-BDC = 2-amino-1,4-benzenedicarboxylate, DMF = N,N-dimethylformamide) which was found to exhibit a very good sensitivity for the medium temperatures (100 K < T < 293 K), with a maximum relative sensitivity (S m ) of 2.6% K −1 at 190 K being very competitive with the other mixed Eu-Tb MOFs operating in the same temperature range.…”