Quantum chemistry computations on chlorpyrifos pesticide based on Density Functional Theory

In this study, quantum chemistry computations based on DensityFunctional Theory (DFT) were performed using the B۳LYP methodand the basis set ۳۱-۶G(d,p) for examining the effect oforganophosphate pesticides on Serine amino acid via hydrogen bondsin water. The interaction between ۶ chlorpyrifos compounds and theirderivatives led to the formation of ۶ different complexes, and thestability energies of these systems were measured. The dipolemoment values are close and approximately from ۳.۶ eV to ۴.۷ eV.The enthalpy and Gibbs free values are positive, indicating theendothermic and nonspontaneous nature of the formation process ofthese complexes. The band gaps, calculated from the energydifference of HOMO and LUMO orbitals, are close and about ۵.۱ eV.Given the close band gap of Serine amino acid, the formation ofstrong hydrogen bonds in all the complexes is likely. The quantummechanicaldescriptors of chlorpyrifos complexes were computed,examined, and used for determining the best complexes. The lengthand angles of the compound bonds before and after the formation ofthe complexes were computed and compared, and the changes in theangles and the general shape of the structures were studiedindividually. In the QTAIM data, the S۱...H-O bonds in all thecomplexes and the intra-molecular hydrogen bond in the O...H-OSerine amino acid had an electrostatic nature. The C-H, N-H, P-O,and C-N bonds were of the covalent type

کلیدواژه ها:

Quantum chemistry computations ، organophosphate ، pesticide ، Density Functional Theory ، hydrogen bond ، chlorpyrifos