Lanthanide-based metal–organic framework materials as bifunctional fluorescence sensors toward acetylacetone and aspartic acid

Abstract

A family of novel lanthanide-based metal–organic frameworks (Ln-MOFs) with bifunctional fluorescence sensing properties, namely, {[(CH₃)₂NH₂]₅[Ln₅(TBAPy)₅]·solvent}_n (Ln = Gd (1), Tb (2), and Dy (3); H₄TBAPy = 1,3,5,7-tetra(4-carboxybenzene)pyrene), was synthesized and structurally characterized. Structural analysis reveals that Ln-MOFs1–3 are isomorphic, and Gd-MOF1 has a three-dimensional structure with a porosity of 20.40%. Due to the existence of the pyrene ring featuring a conjugated system, Ln-MOFs1–3 exhibit strong fluorescence emission. Interestingly, Ln-MOFs1–3 could be considered as good bifunctional fluorescence sensors toward acetylacetone and aspartic acid via a turn-on effect. The detection limits of Tb-MOF2 toward acetylacetone and aspartic acid are 0.129 and 0.025 ppm, respectively. Furthermore, the probable sensing mechanisms for target analytes were also discussed in detail.