Tandem Förster Resonance Energy Transfer Induced Luminescent Ratiometric Thermometry in Dye‐Encapsulated Biological Metal–Organic Frameworks

Abstract Luminescent ratiometric thermometers (LRTs) based on the emission intensity ratio with self‐reference functions guarantee a temperature sensing of fast response, high precision, and excellent spatial resolution. For monitoring temperature at the cellular level, the use of metal–organic frameworks (MOFs) as probes, especially biocompatible ones, is still in its nascency. By employing a biological MOF, Zn₃(benzene‐1,3,5‐tricarboxyl)₂(adenine)(H₂O) (ZnBTCA), as a host and thermosensitive fluorescent dyes as guests, a series of dye@ZnBTCA is synthesized and studied as potential LRT materials, featuring a unique mechanism of tandem Förster resonance energy transfer among the MOF host and the multiple dye guests. This scenario is significantly different from the commonly reported lanthanide or mixed‐lanthanide MOFs where energy transfer occurs between lanthanide ions. Acf‐RB@ZnBTCA, in particular, not only exhibits highly efficient ratiometric temperature‐sensing properties under physiological cellular conditions but also can be excited under visible light.