Modified calix[4]arene with pyrene sulfonyl linkage: Fluorescence and electrochemical sensor for the detection of paraquat in potatoes via host–guest chemistry

Abstract

In this presented work, we propose a new calix[4]arene-pyrene based supramolecular fluorescence system C4Py, constructed for the recognition of paraquat (PQ) herbicide. The proposed method shows fluorescence “turn-off” effect while binding of PQ with C4Py, by quenching the fluorescence intensity of C4Py. Excellent selectivity for PQ is demonstrated by a comparison with other various types of pesticides. The limit of detection is found to be 7.14 µM by fluorescence experiment. The recognition event has been confirmed by 1H NMR as well as MALDI-TOF analysis. This approach was validated by PQ with spiking experiments using potatoes as real sample, exhibiting 7.692 ppm limit of detection. For the further confirmation of C4Py: PQ binding, the electrochemical study was also carried out using cyclic voltammetry and differential pulse voltammetry. The results of electrochemical study demonstrated a decrease of the oxidation peak current on increasing concentration of PQ into C4Py solution confirming binding of PQ with C4Py.