Luminescence switching of CdTe quantum dots in presence of p-sulfonatocalix[4]arene to detect pesticides in aqueous solution.

A simple, rapid, and sensitive identification method of fenamithion and acetamiprid is developed using supramolecular nano-sensitizers combining of CdTe quantum dots (QDs) and p-sulfonatocalix[4]arene as additive by fluorescent spectroscopic technique in water. Depending on p-sulfonatocalix[4]arene, the selectivity of CdTe QDs is tuned between fenamithion and acetamiprid. The luminescence of free CdTe QDs is quenched selectively to fenamithion. While in the presence of p-sulfonatocalix[4]arene, it shows that the fluorescence intensity of QDs is enhanced selectively to acetamiprid due to the cooperation of QDs and p-sulfonatocalix[4]arene. Based on the response characteristics of the QDs, a fluorescent method is performed for tuning selective determination of the pesticides. Under optimum conditions described, it is found that the pesticides effect on the luminescence of the CdTe QDs in concentrations dependence are described by a Stern-Volmer-type equation or a Langmuir binding isotherm equation in the range of 0-10(-4)M (fenamithion) and 0-10(-3)M (acetamiprid), with the corresponding detection limits (3sigma) of 1.2 x 10(-8)M (fenamithion) and 3.4 x 10(-8)M (acetamiprid), respectively. The possible mechanism is discussed.