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Triple-Interpenetrated Lanthanide-Organic Framework as Dual Wave Bands Self-Calibrated pH Luminescent Probe

Hou, Sheng-Li, Dong, Jie, Tang, Meng-Hua, Jiang, Xiao-Lei, Jiao, Zhuo-Hao, Zhao, Bin
Analytical chemistry 2019 v.91 no.8 pp. 5455-5460
anions, cations, encapsulation, ferric oxide, health status, ligands, luminescence, magnetic materials, magnetism, monitoring, nanoparticles, nitrates, pH, protons, solvents, water quality
pH value is a key parameter in reflecting the health status, reaction process, and water quality. The construction of highly sensitive pH luminescent ratiometric is important but challenging. Herein we designed and synthesized a unique triple-interpenetrated luminescent lanthanide-organic framework {[Eu(PPTA)₀.₅(NO₃)(DMF)₂]·H₂O}ₙ(V104) based on an amphoteric ligand 4,4′,4′′,4′′′-(1,4-phenylenebis(pyridine-4,2,6-triyl))tetrabenzoic acid (H₄PPTA). Compound V104 possesses high solvent and acid/alkaline stabilities. Luminescent investigations reveal that V104 exhibits dual emission peaks at 390 and 480 nm, and these two peaks can separately detect OH– and H⁺ among various anions and cations. Importantly, V104 can serve as a self-calibrated pH ratiometric to quantitatively detect pH value, and the sensitivity can reach 403.2% per pH for OH–, and 129.5% per pH for H⁺. Furthermore, by encapsulating magnetic γ-Fe₂O₃ nanoparticles in V104, the pH sensor can be readily separated from the analyte by external magnet and recycled at least four times, suggesting as-synthesized γ-Fe₂O₃@V104 has potential for monitoring pH fluctuations in water. To our knowledge, this is the first self-calibrated ratiometric pH-sensor based on two responsive wave bands which can separately detect OH– and H⁺.