Comparative Analysis of the Chemical Reactivity and Physicochemical Properties of Selective and Non-selective Herbicides
N’GUESSAN Kouakou Nobel
Laboratory of Thermodynamics and Environmental Physical Chemistry, UFR SFA, Nangui Abrogoua University, Abidjan, Côte d’Ivoire.
OYEDELE Sampson Oladapo
Institute for Research into New Energy (IREN), UFR SFA, Nangui Abrogoua University, Abidjan, Côte d’Ivoire.
BLEHOUE Clémence Ingrid
Department of Physics and Chemistry, Faculty of Science and Technology, Alassane Ouattara University of Bouaké, Côte d'Ivoire.
Traore Dramane
Laboratory of Thermodynamics and Environmental Physical Chemistry, UFR SFA, Nangui Abrogoua University, Abidjan, Côte d’Ivoire.
DEMBELE Georges Stéphane
Laboratory of Thermodynamics and Environmental Physical Chemistry, UFR SFA, Nangui Abrogoua University, Abidjan, Côte d’Ivoire.
Koudjina Simplice
Laboratory of Chemical Physics-Materials and Molecular Modeling (LCP3M) University of Abomey-Calavi (UAC), Cotonou, Bénin.
OUATTARA Wawohinlin Patrice
Laboratory of Thermodynamics and Environmental Physical Chemistry, UFR SFA, Nangui Abrogoua University, Abidjan, Côte d’Ivoire.
KONE Mamadou Guy-Richard *
Laboratory of Thermodynamics and Environmental Physical Chemistry, UFR SFA, Nangui Abrogoua University, Abidjan, Côte d’Ivoire.
BAMBA Kafoumba
Laboratory of Thermodynamics and Environmental Physical Chemistry, UFR SFA, Nangui Abrogoua University, Abidjan, Côte d’Ivoire.
ZIAO Nahossé
Laboratory of Thermodynamics and Environmental Physical Chemistry, UFR SFA, Nangui Abrogoua University, Abidjan, Côte d’Ivoire.
*Author to whom correspondence should be addressed.
Abstract
This study compared electronic reactivity and selected physicochemical properties of eight herbicides classified as selective or non-selective: glyphosate, butachlor, clethodim, fluazifop, fosamine, glufosinate, paraquat and propanil. Molecular geometries were optimised using density functional theory at the CAM-B3LYP/6-31G level. Frontier molecular orbitals, global reactivity descriptors and condensed Fukui indices were examined, while EPI Suite provided structure-based estimates of lipophilicity, water solubility, bioconcentration, bioaccumulation and persistence. The reported HOMO–LUMO energy gaps ranged from 2.933 to 9.081 eV. Clethodim exhibited the smallest gap and highest tabulated electrophilicity index, whereas glyphosate had the largest gap and greatest chemical hardness. The local reactivity indices suggested variation in preferred atomic sites across the molecular structures, with carbon atoms predominating in the reported assignments. Estimated lipophilicity, solubility and bioaccumulation-related descriptors also differed among the compounds. However, these results describe molecular and model-based properties rather than experimentally measured herbicidal activity, crop selectivity or environmental risk. Interpretation is constrained by the assumptions of the DFT approach and the applicability of the EPI Suite prediction models, particularly for ionisable structures. Furthermore, the software inputs and derivation of persistence values were incompletely specified, and some reported physicochemical results require reconciliation with the original outputs. The analysis therefore provides a comparative theoretical framework for the selected herbicides and identifies the need for computational verification and experimental assessment before broader biological or environmental conclusions are drawn.
Keywords: Glyphosate, selective herbicides, non-selective herbicides, density functional theory, physicochemical properties