A multifunctional fluorescence probe based on a new Cd-MOF for HSO4−, acidic amino acids, and continuous basic amino acids detection

A multifunctional probe Cd-MOF was successfully prepared by hydrothermal reaction using Cd2+ as a node, 1,3,5-triimidazoly benzene (L) and ligands D(+)-camphoric acid (D-H2cam) as linkers. It was characterized by single crystal X-ray diffraction (XRD), powder X-ray diffraction (PXRD), chromaticity coordinates (CIE), and thermogravimetric analysis (TGA). The study of fluorescence properties revealed that the fluorescence of Cd-MOF at 325 nm was significantly quenched in the presence of HSO4− or acidic amino acids (glutamate (Glu) or aspartic acid (Asp)) because of the formation of hydrogen bonds between analyte and Cd-MOF. Interestingly, the in-situ generated [Cd-MOF-Glu/Asp] system could be used for relay recognition of basic amino acids arginine (Arg) and lysine (Lys). Fluorescence could be 'turned on' under the same experimental conditions. This could be attributed to the destruction of the hydrogen bond between Cd-MOF and acidic amino acids. The sensing process possessed outstanding sensitivity and selectivity, rapid time responsiveness, and recyclability in aqueous solution. Finally, the sensing mechanisms of Cd-MOF and [Cd-MOF-Glu/Asp] systems were investigated by PXRD, UV spectroscopy, and DFT theoretical calculations.