Nanomolar Level Fluorogenic Detection of Cyanide with an Amide Functionalized Zirconium Metal-Organic Framework and its Application in Real-World Cyanide Monitoring
14 Pages Posted: 15 Jan 2022
Abstract
This work contains synthesis of a di-amide linker based Zr(IV) metal-organic framework (MOF, 1) and its characterisation with by PXRD, elemental analysis, FE-SEM, EDX and FT-IR analysis and application for the detection of toxic cyanide in aqueous medium. Furthermore, the physicochemical stability of the sensor was judged by the thermogravimetric analysis (TGA) and PXRD analysis. TGA curve of 1 displayed that the thermal stability of the probe was up to 230 °C. The MOF material was stable in sensing medium and in wide pH range (pH = 2-8) which were confirmed by PXRD analysis of the recovered samples. The surface area (BET) of this porous sensor was 672 m2/g with a pore volume of 0.36 cm3/g at p/po = 0.5. Guest free form of the MOF material (1′) displayed its high efficiency for the fluorescence recognition of cyanide (CN-) with an extraordinary limit of detection of 76.4 nM in aqueous medium. Comparable recognition time (10 min) as the other available chemosensors of CN- ion and sensing of CN- using easily portable paper strips make this probe an extraordinary chemosensor of CN- ion. Together with paper strip based sensing, detection of CN- in apple seeds, various real water samples and wide ranges of pH solutions are the special features of the probe. The abstraction of amide proton by CN- ion favours 'turn-on' sensing, which was revealed by 1H-NMR titration. This sensor of cyanide can also be used as luminescent switch due to its reversible nature of sensing.
Keywords: Metal-organic framework, amide functionalization, cyanide sensing, Fluorescence turn-on, real world applications
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