Luminescent Thermometer Based on a Praseodymium(iii) Cyanide-Based Metal-Organic Framework

Trivalent lanthanide ions have emerged as promising candidates for precise and remote temperature sensing. Among them, Pr³⁺-based luminescent thermometers remain underexplored, particularly those operating in the near-infrared (NIR) spectral region. This work presents the synthesis and thorough characterization of a novel Pr³⁺-based coordination polymer, {[Pr₂^IIIPt₃^II(CN)₁₂(4,4'-bpyO₂)₄(H₂O)₆]·4H₂O}_n (1), as a rare example of Pr³⁺ luminescent thermometry. Coordination between Pr³⁺ ions, cyanido-bridged Pt²⁺ centers, and 4,4'-bpyO₂ ligands enables efficient energy transfer, producing luminescence in visible and near-infrared regions. The polymer demonstrates distinct temperature-dependent luminescence over a wide range (12-386 K), with relative thermal sensitivities of ≅1%·K^-1 and a minimum temperature uncertainty of 0.2 K.