Here we have studied the complexation of caffeic, ferulic and p-coumaric acids with Al(III) under physiological conditions (i.e. at 37 °C and in 0.16 M NaCl). Solubility and protonation constants of these hydroxycinnamic acids were firstly determined in order to evaluate the competition of the ligands for the Al(III) and H+ ions. Speciation analysis made by potentiometric titrations and supported by UV and 1H-NMR data shows that a pH-dependent complexation occurs at 1[thin space (1/6-em)]:[thin space (1/6-em)]1 and 2[thin space (1/6-em)]:[thin space (1/6-em)]1 ligand-to-Al(III) ratios. Notably, these data combined with computational (DFT) results unequivocally indicate that the complexation site is the carboxylate group of the ligands thus excluding any involvement of the phenolic sites.

Complexation behaviour of caffeic, ferulic and p-coumaric acids towards aluminium cation: a combined experimental and theoretical approach

Beneduci A;FURIA, Emilia
;
Russo N;MARINO, Tiziana
2017

Abstract

Here we have studied the complexation of caffeic, ferulic and p-coumaric acids with Al(III) under physiological conditions (i.e. at 37 °C and in 0.16 M NaCl). Solubility and protonation constants of these hydroxycinnamic acids were firstly determined in order to evaluate the competition of the ligands for the Al(III) and H+ ions. Speciation analysis made by potentiometric titrations and supported by UV and 1H-NMR data shows that a pH-dependent complexation occurs at 1[thin space (1/6-em)]:[thin space (1/6-em)]1 and 2[thin space (1/6-em)]:[thin space (1/6-em)]1 ligand-to-Al(III) ratios. Notably, these data combined with computational (DFT) results unequivocally indicate that the complexation site is the carboxylate group of the ligands thus excluding any involvement of the phenolic sites.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11770/138438
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