Turn-On Luminescent Sensor toward Fe³⁺, Cr³⁺, and Al³⁺ Based on a Co(II) Metal–Organic Framework with Open Functional Sites

Abstract

A novel Co-based metal-organic framework (MOF) with the formula of {[Co₃(BIBT)₃(BTC)₂(H₂O)₂]·solvents}_<i>n</i> (<b>JXUST-2</b>, where <b>JXUST</b> denotes Jiangxi University of Science and Technology, BIBT = 4,7-bi(1<i>H</i>-imidazol-1-yl)benzo-[2,1,3]thiadiazole, and H₃BTC = 1,3,5-benzenetricarboxylic acid) has been solvothermally prepared, which takes 3D structure with a rare 3,4,6-c topology and contains intramolecular hydrogen bonds. Interestingly, the sensing investigations suggest that <b>JXUST-2</b> could be considered as a multifunctional fluorescence sensor toward Fe³⁺, Cr³⁺, and Al³⁺ via a turn-on effect with good reusability and detection limits of 0.13, 0.10, and 0.10 μM, respectively. The turn-on effect of <b>JXUST-2</b> could be ascribed to an absorbance caused enhancement (ACE) mechanism. Notably, <b>JXUST-2</b> is the first turn-on MOF fluorescent sensor for Fe³⁺, Cr³⁺, and Al³⁺ simultaneously.