Multi-Emitting Ratiometric Temperature Sensing and Tunable White Light Emitting Based on Effective Energy Transfer in...

Isostructured lanthanide-Brønsted acidic ionic liquid coordination polymers, {[Ln(C₇H₇N₂O₄)(H₂O)₄]Cl₂} (LnIMDC(H₂O)₄, Ln = Eu³⁺, Gd³⁺, or Tb³⁺, C₇H₇N₂O₄ = [IMDC]^-) and {[Eu_0.5Tb_0.5(C₇H₇N₂O₄)(H₂O)₄]Cl₂} (Eu_0.5Tb_0.5IMDC(H₂O)₄)), have been synthesized using 1,3-bis(carboxymethyl) imidazolium chloride ([H₂IMDC]Cl) as linkers. LnIMDC(H₂O)₄ (Ln = Eu³⁺ or Tb³⁺) and Eu_0.5Tb_0.5IMDC(H₂O)₄ exhibit good temperature sensing performance over a wide temperature range with maximum sensitivities S_r of 2.73%·K^-1 (392 K) and 2.74%·K^-1 (362 K), and 2.21% K^-1 (383 K), respectively. Meanwhile, the white light emission of Eu_0.5Tb_0.5IMDC(H₂O)₄ was achieved with Commission Internationale de l'Eclairage coordinates of (0.323, 0.328), a correlated color temperature of 5942 K, and a color rendering index (CRI) of 90. Moreover, the temperature response of the as-synthesized Eu_0.5Tb_0.5IMDC(H₂O)₄@PDMS film was monitored. The energy transfer efficiency and phosphorescence lifetime in the abovementioned coordination polymers were investigated to explore the energy transfer efficiency between [IMDC]^- and Ln³⁺ as well as between Tb³⁺ and Eu³⁺.