Etude des interactions dans le système supramoléculaire pesticide /Cyclodextrine native

Abstract

In this work, we studied the complexation of the Methomyl molecule with β-cyclodextrin. This study, we only considered the 1:1 stoichiometry. We simulated the inclusion of Methomyl in β-CD using the semi-empirical PM6 method, DFT, and the ONIOM2 and NBO methods. The complexation and interaction energies for the two considered orientations are reported. We found that orientation (B) is more stable, and statistical thermodynamic calculations at 1 atm and 298.15K have demonstrated that in a vacuum, the complexation process is exothermic and enthalpically favorable. The calculated negative complexation energy suggests that the inclusion complexes are stable. The HOMO and LUMO orbital investigations confirm the better stability of orientation (B). Finally, the NBO analysis was conducted on complexes optimized using the ONIOM2 method to quantify the donor-acceptor interactions between Methomyl and β-CD. In the solvent, the HOMO and LUMO orbital investigations confirm the better stability of orientation (A) of the inclusion complex. We observe that molecular interaction and the solvent environment lead to a modification of the reactivity and stability of the compounds