Effet de solvant sur les dérivés de l’acide cinnamique. Étude quantique

Abstract

Complexation is the main phenomenon responsible of metal retention in soils. Humic substances (HS) are the major components implied. Their complexing properties are due to functional groups such as phenolic and carboxylic functions. Nevertheless the study of metallo-humic interactions is limited by the size and polyfonctionality of HS. The use of low molecular sized model molecules of some cinnamic acid derivatives, having similar fixation sites in competition as those met in HS, enables to gain more insight into the complexation phenomenon. The complexation of three ligands : caffeic acid, dihydrocaffeic acid, dopacitic acid by Al (III) with solvent effect by using mixed salvation approach, was studied. Quantium chemistry methods combined to electronic spectroscopy have enabled to characterize the structures of formed complexes, the first site of fixation, effect of the electronic delocalization thus the effect of carbonic chain length.