Cryogenic Nanothermometer Based on the MIL‐103(Tb,Eu) Metal–Organic Framework

The microporous metal–organic framework MIL‐103 doped with Tb 3+ and Eu 3+ , formulated as [(Tb 0.95 Eu 0.05 )(btb)(H 2 O)] · (solv) x [H 3 btb = 1,3,5‐tris(4‐carboxyphenyl)benzene; solv = H 2 O, CH 3 OH] has been shown to be a good platform for luminescent ratiometric thermometry. Although operative over a wide range of temperatures (10–320 K), this material exhibits, in the cryogenic range (<100 K), one of the best performances of metal–organic frameworks, with a relative thermal sensitivity of 2.85 %   K –1 at 14 K. The material exists in the form of nanoparticles, suitable for nanothermometry applications (e.g., microfluidics). Moreover, as MIL‐103 is nanoporous, its use as a multisensing platform deserves further consideration in the near future.