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Structural characterization of aluminium (III) and iron (III) complexes of coumarinic acid in aqueous solution from combined experimental and theoretical investigations

Abstract

Here we have studied the complexation of coumarin-3-carboxylic acid with Al(III) and Fe(III) at 37°C and in 0.16 mol L-1 NaCl. The protonation constant of coumarin-3-carboxylic acid was determined in order to evaluate the competition of the ligand for the metal cations and H+. Speciation profiles obtained by potentiometric titrations and supported by UV and 1H- and 13C- NMR data show that a complexation occurs at 1:1 ligand-to-Al(III) ratio and at 1:2 ligand-to-Fe(III) ratio. These data were supported by a computational evaluation which highlighted the different structural behaviour of the two metals in the complexes. Indeed, the Al(III) cation forms bidentate complexes involving a 6-membered ring by binding both the carboxyl oxygens of the ligand. In contrast, the Fe(III) ion preferentially forms monodentate tetrahedral complexes on the carboxylate moiety of the HCCA ligand.

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Publication details

The article was received on 13 Mar 2018, accepted on 16 May 2018 and first published on 18 May 2018


Article type: Paper
DOI: 10.1039/C8NJ01244J
Citation: New J. Chem., 2018, Accepted Manuscript
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    Structural characterization of aluminium (III) and iron (III) complexes of coumarinic acid in aqueous solution from combined experimental and theoretical investigations

    E. Furia, A. Beneduci, N. Russo and T. Marino, New J. Chem., 2018, Accepted Manuscript , DOI: 10.1039/C8NJ01244J

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