A multifunctional benzothiadiazole-based fluorescence sensor for Al3+, Cr3+ and Fe3+

Abstract

A new benzothiadiazole-based MOF {[Zn(BIBT)(oba)]·DMA}_n (JXUST-3, BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and H₂oba = 4,4′-oxybisbenzoate) has been solvothermally synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy and TGA. The fluorescence studies suggest that JXUST-3 could simultaneously selectively sense trivalent metal ions including Al³⁺, Cr³⁺ and Fe³⁺ by a turn-off effect, and the detection limits are 0.055, 0.049 and 0.056 μM, respectively. Moreover, JXUST-3 exhibits relatively good thermal and chemical stabilities and reusability. The fluorescent test paper also displayed an obvious turn-off effect, indicating that JXUST-3 can be used as a potential multi-response fluorescent probe. The possible quenching mechanisms of JXUST-3 for Al³⁺ and Fe³⁺ were competitive energy absorption, and for Cr³⁺ ions, they were competitive energy absorption and weak interactions between Cr³⁺ and the framework. Therefore, JXUST-3 could be viewed as a transition metal MOF fluorescence sensor for Al³⁺, Cr³⁺ and Fe³⁺ by the turn-off effect, simultaneously.