Eu~(3+) or Sm~(3+)-Doped terbium-trimesic acid MOFs: Highly efficient energy transfer anhydrous luminophors

摘要

[Tb(TMA):RE3+] MOFs (MOF: Metal Organic Framework; TMA: trimesic acid or 1,3,5-benzenetricarboxylic acid, RE3+: Eu and Sm) with tunable color were synthesized by aqueous coprecipitation method. Using a chemical artifice, lanthanide cationic radius contraction, it was possible to obtain only anhydrous MOFs, a very important characteristic in luminescent compounds. TMA(3-) anions triplet states present higher energy levels compared to the main emitting states of Eu3+ (D-5(0)), Tb3+ (D-5(4)) and Sm3+ ((4)G(5/2)), supplying an efficient antenna effect. Based on the spectroscopic investigation, i.e. excitation/emission spectra and lifetimes of the excited states, the material shows a high quantum efficiency (eta = 83-86%) due to the very efficient energy transfer process TMA -> Tb -> Eu, combined to the presence of this high energy absorption ligand and the absence of water molecules.