Computational study of influence of the ability of lapachol and its derivatives to chelate iron (ii) cation on the antioxidant properties Djafarou Ngouh Pajoudoro , Désiré Bikele Mama Department of Chemistry, Faculty of Science, University of Douala, Cameroon The study of the chelation of Lapachol and its derivatives by Fe 2+ cation has been performed at B3LYP/6- 311++G(d,p) level in four media study: gas phase, water, acetonitrile, benzene and toluene . This investigation exclusively focused on bi-dentate and tri-dentate binding of Fe 2+ of twenty two complexes indicated proportionality between the MIA values and the retained charge on Fe 2+ cation for k 2 -(O 1 ,O 2 ) modes. But, an inverse an inverse proportionality has been observed between these two parameters for k 3 -(O 2 , C=C) modes. The higher stability has been yielded for a tri-dentate coordination mode in which the Fe 2+ cation is simultaneously attached to the two carbon atoms of the ethylenic bond (C=C) and sp 2 O 3 oxygen atom. In this coordination mode in gas phase, the topological analysis of complexes exhibits the fact that the electron density has shown to be concentrated between the oxygen atom of the ligand attached to Fe 2+ and this metal cation. Moreover, the hydrogen bond (HB) strength calculated using the quantum mechanics atom in molecule (QMAIM) theory for isolated ligands situated between 23.92 and 30.15 kJ/mol is in the range of normal HBs. Collectively; all the complexation processes have been found to be highly exothermic. Our results have also shown that the electron extraction from Fe 2+ ...La i complexes is most difficult than in the one in free ligand. This electron transfer from ligand to Fe 2+ cation is more pronounced in the complexation mode integrating the C=C double bond. References 1. L. Mammino, “Investigation of the antioxidant properties of hyperjovinol a through its Cu(II) coordination ability”, Journal of Molecular Modeling , vol. 19, pp.2127-2142, 2013. 2. X.Yunsheng; Z. Youguang,; A.Lin,; Yunyan, D.; L Yi, ,”Density Functional Theory of the Structure-Antioxidant Activity of Polyphenolic Deoxybenzoins” Journal of Food Chemistry, vol 151,pp.198–206,2014. 3. Y. Chen, H. Xiao, J. Zheng, and G. Liang, “Structure thermodynamics-antioxidant activity relationships of selected natural phenolic acids and derivatives: an experimental and theoretical evaluation,” PLoS ONE , vol. 10, pp.3, 2015.
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