Mixed-Lanthanoid Metal–Organic Framework for Ratiometric Cryogenic Temperature Sensing

Abstract

A ratiometric thermometer based on a mixed-metal Ln(III) metal-organic framework is reported that has good sensitivity in a wide temperature range from 4 to 290 K and a quantum yield of 22% at room temperature. The sensing mechanism in the europium-doped compound Tb0.95Eu0.05HL (H4L = 5-hydroxy-1,2,4-benzenetricarboxylic acid) is based not only on phonon-assisted energy transfer from Tb(III) to Eu(III) centers, but also on phonon-assisted energy migration between neighboring Tb(III) ions. It shows good performance in a wide temperature range, especially in the range 4-50 K, reaching a sensitivity up to 31% K(-1) at 4 K.

Ligand‐Assisted Back Energy Transfer in Luminescent TbIII Complexes for Thermosensing Properties

“…The energy transfer process from Tb III to Eu III in a lanthanide coordination polymer has also been used for a ratiometric luminescent thermosensor . Thermosensitive paints that contain luminescent lanthanide complexes have also been widely investigated …”

Ratiometric Thermometer Based on a Lanthanoid Coordination Polymer

“…Recently, we reported a ratiometric thermometer based on the europium‐doped terbium compound of the ligand 5‐hydroxy‐1,2,4‐benzenetricarboxylic acid, which appeared to be highly sensitive in the cryogenic temperature range of 0–50 K . We further extended our investigations on the temperature‐dependent properties of such lanthanoid coordination polymers; herein we report a ratiometric thermometer based on an La III /Tb III coordination polymer.…”

“…Earlier we reported the compounds TbH L and EuH L , which were synthesized using the same ligand H 4 L under the same hydrothermal conditions . The new compound LaH L crystallizes in a different structure, which is most likely due to the different ionic radii of La III , Tb III , and Eu III , .…”

Metal–Organic Frameworks in Modern Physics: Highlights and Perspectives

“…Suitable MOF designs [54] ensure that the exciton energy can be transferred from several tens to several hundred nanometers. [55] Intriguingly, the structure of MOFs also affects the exciton migration path, as it was discovered that mixed Ru/Os structures constituted 1D or 3D hopping networks. [46] It has been shown that energy transfer by excitons can be described by a Dexter triplet-to-triplet (exchange) mechanism with multistep incoherent exciton hopping, or a Förster mechanism involving one-step jumping over longer distances.…”