Antagonistic interaction of Pb2+- Al3+ ion pair with Sugar derived Carbon dots: Visual monitoring of Al 3+ ions

In the present study, Maillard reaction assisted route is followed to yield carbon dots from commercialy available table sugar. The system is characterized using High-resolution transmission electron microscopy (HR-TEM), X-ray Photo electron spectroscopy (XPS), X-ray diffraction analysis (XRD), Fourier Transform Infra-Red spectroscopy (FTIR), Dynamic light scattering analysis (DLS) and photoluminescence spectroscopy. The system is found to be highly susceptible for aggregation in the presence of Pb2+ ions, which induced quenching of luminescence of these dots. The aggregation of carbon dots is destroyed and the luminescence was restored in prescence of trace amounts (parts per trillion) of Al3+ ions. This highly specific observation introduces the concept of Ion antagonism of the said ions. The visible re-dispersal of carbon dots in presence of Al3+ ions enables naked eye monitoring of theseions, whose quantification is achieved through simple turbidimetry. Based on this, the presence of Humic acid functionalities on the carbon core is suggested. Hence through this study, apart from the identification of a novel antagonistic ion-pair, a prediction on the surface functional groups on the carbon core is made in the case of carbon dots derived from sucrose via Maillard reaction.