A Eu/Tb mixed lanthanide coordination polymer with rare 2D thick layers: Synthesis, characterization and ratiometric temperature sensing

Highlights: • A new Eu/Tb mixed metal-organic framework (Eu_0.0316Tb_0.9684BTPTA) was synthesized. • This 3D framework is comprised of 2D thick layers. • The intensity ratio of Tb³⁺ and Eu³⁺ was used for temperature sensing. - Abstract: A series of lanthanide coordination polymers LnBTPTA (Ln = Eu, Tb, Eu_xTb_1−x), was synthesized using a tricarbocylic ligand 4,4′,4′′-(benzene-1,3,5-triyltris(1H-pyrazole-3,1-diyl))tribenzoic acid (H₃BTPTA). X-ray single crystal analyses reveal that the asymmetric unit cell contains seven crystallographically independent metal ions and seven crystallographically independent ligands which is quite unusual. The 3D framework is comprised of 2D thick layers stacked through van der Waals force, π-π interactions and hydrogen bonding interactions. Eu_0.0316Tb_0.9684BTPTA presents a dual-emission of Tb³⁺ at 543 nm and Eu³⁺ at 617 nm, and the intensity ratio shows an excellent linear relationship with the temperature changing in 25–225 K. The relative sensitivity 0.45–5.12% K⁻¹ is much higher than those have been reported in the same detection range.