pH influence on the complexation site of Al(III) with protocatechuic acid. A spectroscopic and theoretical approach - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy [1994-...] Année : 2013

pH influence on the complexation site of Al(III) with protocatechuic acid. A spectroscopic and theoretical approach

Résumé

Electronic spectroscopy techniques with the aid of quantum chemical calculations, and notably the Time-Dependent Density Functional Theory, can be used to probe the structure of metal complexes in solution. Here, we report the characterization of Al(III)-protocatechuate in aqueous solution, at pH = 6.5. The exploitation of the UV-vis spectra of the system by chemometric methods highlights the formation of a single complex of stoichiometry 1:1. From different structural hypothesis, the comparison of theoretical and experimental spectra shows that Al(III) forms a monodentate complex with the carboxylate function. This hypothesis is confirmed by the calculation of the complexation reaction pathways. Previous studies report the formation of a chelate involving the ortho-dihydroxyl group, at pH = 3.5. These results illustrate the important dependence of the protonation state of the carboxylic function on the Al(III) fixation site on the studied ligand.

Dates et versions

hal-00807472 , version 1 (03-04-2013)

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J.P. Cornard, C. Lapouge, E. André. pH influence on the complexation site of Al(III) with protocatechuic acid. A spectroscopic and theoretical approach. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy [1994-..], 2013, 108, pp.280 - 287. ⟨10.1016/j.saa.2013.02.005⟩. ⟨hal-00807472⟩
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