Multi-functional lanthanide-CPs based on tricarboxylphenyl terpyridyl ligand as ratiometric luminescent thermometer and highly sensitive ion sensor with turn on/off effect

Abstract

A series of isostructural lanthanide coordination polymers (Ln-CPs) formulated as [Ln(tcptpy)(H₂O)₂·2H₂O]_n {Ln³⁺ = Sm³⁺ (1), Eu³⁺ (2), Gd³⁺ (3), Tb³⁺ (4), Dy³⁺ (5); H₃tcptpy = 4-(2,4,6-tricarboxylphenyl)-4,2′:6′,4′′-terpyridine} has been afforded and characterized systematically. Their structures were established by single-crystal X-ray diffraction. All the complexes feature two dimensional (2D) layers with (4,4)-connected topology. By virtue of the isostructural frameworks, a family of binary co-doped Ln-CPs [Tb_1−xEu_xtcptpy]_n was achieved for ratiometric temperature sensors, among which Tb_0.897Eu_0.103tcptpy exhibits a good linear response to the temperature range from 305–340 K, with a maximum relative sensitivity (S_m) of 8.41% K⁻¹ at 340 K. Moreover, Tb-CPs exhibit excellent applications as luminescent sensors for the detection of nitrobenzene and Fe³⁺ cations with high selectivity and sensitivity based on a luminescence quenching approach. The possible mechanisms of the fluorescence quenching effect were also investigated.