Developing Luminescent Ratiometric Thermometers Based on a Covalent Organic Framework (COF)
Covalent Organic Frameworks (COFs) an emerging class of crystalline porous materials, are proposed here as a new type of support for grafting lanthanide ions (Ln3+ and employing these hybrid materials as ratiometric luminescent thermometers. A TpBpy COF prepared from 1,3,5 triformylphloroglucinol (Tp) and 2,2' bipyridine 5,5' diamine (Bpy) grafted with Eu/Tb and Dy acetylacetone (acac) complexes can be successfully used as luminescent thermometers in the 10 360 K and 280 440 K ranges, respectively, exhibiting good sensing properties (thermal sensitivity up to 1.403 %K 1, temperature uncertainty T 1 K above 110 K) For the Eu/Tb systems we observe a quite unusual and rarely reported behavior in which there is no thermal quenching of the Tb3+emission, as a result of the absence of ion to ligand/host energy back transfer. The LnCOF materials proposed here could be a new class of materials employed for temperature sensing applications following up the well known Metal Organic Framework luminescent thermometers.
Angewandte Chemie