Template-directed synthesis of a luminescent Tb-MOF material for highly selective Fe3+ and Al3+ ion detection and VOC vapor sensing

Abstract

A flexible bidentate polyaromatic acid ligand 4,4′-oxybis(benzoic acid) (H₂oba) was used for the construction of a novel luminescent Tb(III)-based metal–organic framework (MOF), namely {(Me₂NH₂)[Tb(OBA)₂]·(Hatz)·(H₂O)_1.5}_n, with 3-amino-1,2,4-triazole (Hatz) as the template reagent. In the structure of the Tb-MOF, there co-exist single-stranded and double-stranded helical chains along the c axis, and the overall network shows a three-fold interpenetrated qtz net. This MOF is capable of selectively sensing Fe³⁺ and Al³⁺ ions in water via quenching the luminescence and tuning the emission ratio between the ligand-based and metal-based luminescence, respectively. More importantly, this MOF can realize fast detection for p-xylene (PX) vapor with a response time of less than 10 s and 40% fluorescence enhancement, while nitrobenzene (NB) vapor could lead to a quenching effect in 10 min with a 75% quenching efficiency. Remarkably, this is the first example of a multi-responsive luminescent Tb-MOF sensor for Fe³⁺ and Al³⁺ ions and VOC vapor detection. In connection to these, the probable sensing mechanisms were also discussed in this paper.