Estudo teórico da inclusão dos pesticidas Paraoxon, Paration e Metil-Paration em alfa-ciclodextrina

Abstract

With an increase in agricultural production, the pesticide use has intensified. Pesticides, when applied responsibly, can help protect the target ecosystem, but concomitantly, the wrong administration can lead to negative environmental impacts mainly through soil and water contamination. There are currently several processes for treating different matrices contaminated with pesticides. Among these, we have the use of cyclodextrins as physical-chemical remedies. In the present work, a theoretical study was carried out on inclusion compounds formed with the organophosphate pesticides paraoxon (PRX), methy parathion (MPTN) and parathion (PTN) in α-cyclodextrin (α-CD). The procedure to estimate the equilibrium constants for the inclusion of pesticides is discussed in terms of intervals for the supramolecular parameters used in the exploration of the potential energy surface (PES) by the semi-empirical quantum method GFN2-xTB. As a result, when investigating various inclusion modes, it was identified that proper exploration of PES provides a reliable prediction of the equilibrium constant for inclusions in the solution. Furthermore, with the study of different initial associations, for PTN/α-CD, was achieved excellent linear coordination (R2 =0,987) between theoretical and experimental data. This study indicates that the semi-empirical GFN2-xTB method can be used for the characterization of supramolecular systems. The data obtained in these studies can be used as a starting point for more accurate calculations using quantum methods such as DFT.