Isostructured lanthanide-Brønsted acidic ionic liquid coordination polymers, {[Ln(C7H7N2O4)(H2O)4]Cl2}n (LnIMDC(H2O)4, Ln = Eu3+, Gd3+, or Tb3+, C7H7N2O4 = [IMDC]-) and {[Eu0.5Tb0.5(C7H7N2O4)(H2O)4]Cl2}n (Eu0.5Tb0.5IMDC(H2O)4)), have been synthesized using 1,3-bis(carboxymethyl) imidazolium chloride ([H2IMDC]Cl) as linkers. LnIMDC(H2O)4 (Ln = Eu3+ or Tb3+) and Eu0.5Tb0.5IMDC(H2O)4 exhibit good temperature sensing performance over a wide temperature range with maximum sensitivities Sr 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 Eu0.5Tb0.5IMDC(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 Eu0.5Tb0.5IMDC(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+.