Computational Chemistry studies of some cyano(3-phenoxyphenyl) methyl isobutyrate derived insecticides and molecular design of novel ones

Abstract

This work was designed to study some isobutyrate derived insecticides (using computational chemistry) and to designed novels ones using quantitative structure activity relationship (QSAR) model. PM 7 quantum chemical descriptors were calculated for cyhalothrin (CYH), fenpropathrin (FEP), cypermethrin (CYP), deltamethrin (DEL), permethrin (PEM) and cyfluthrin (CYF).  Calculated descriptors were frontier molecular energies (including the energy of the highest occupied molecular orbital (E_HOMO), the energy of the lowest unoccupied molecular orbital (E_LUMO) and the energy gap (DE)), the binding energy (E_Bind), the electronic energy (E_Elect), the hydration energy (E_Hyd) and logP.  Those descriptors that exhibited excellent correlations with the experimental LD₅₀ values (of the studied insecticides) were used to derive quantitative structure activity relationship (QSAR). Correlation between the theoretical and experimental LD₅₀ values was excellent (R² = 0.9500). The active sites of reactivity for the insecticides were identified through Fukui function analysis and were supported by their HOMO and LUMO diagrams. Based on the derived quantitative structure activity relationship, eleven (11) novel insecticides were designed and their theoretical activities (which ranged from 1319 to 5630 mg/kg) were comparable and better (in some cases) to the known insecticides. Therefore, quantitative structure activity approached can be effective in molecular design and modelling of insecticides