A diarylethene derived Fe3+ fluorescent chemosensor and its application in wastewater analysis

Abstract A diarylethylene derivative containing an acylhydrazone Schiff base moiety was designed and synthesized. Upon alternative irradiation with UV and visible lights, the compound showed distinct fluorescence switching properties based on fluorescence resonance energy transfer mechanism. On the other hand, the fluorescence can be efficiently quenched by 69 fold in the presence of Fe3+ ion in methanol. As a Fe3+ fluorescent chemosensor, the sensing mechanism, the influence of pH on sensing properties, and the practical application were also studied. In the complex, the breaking of the intramolecular H-bonding between the ―CO = NH― proton and the oxygen at the C = O of lactone, the weaking of electrons transfer, and the paramagnetic nature of Fe3+ induced a consequent decrease fluorescence. The compound was found to be stable in a wide range of pH and a highly efficient Fe3+ ion quencher with a detection limit of 4.6 × 10―6 mol L―1. Moreover, the fluorescent detection of Fe3+ was demonstrated by filter paper strips. A series of test papers with different Fe3+ concentrations were prepared and used as the standard card. The analytical application of measuring Fe3+ concentration in wastewater samples were evaluated by comparison with the standard card directly and quickly.