Ab initio molecular dynamics study of ascorbic acid in aqueous solution

Francesca Costanzo (1)

1 Dipartimento di Chimica Fisica ed Inorganica

The ascorbic radical anion A^*- in aqueous solution is studied using ab initio molecular dynamics based on density functional theory. Calculations of the spin density indicate that both in vacuum and in solution the unpaired electron is largely shared between the two oxygens which in the fully reduced acid AH₂ constitute the acid hydroxyl groups, and the two carbon atoms connecting them. Of these two oxygens, the one carrying the remaining proton is found to be the site with the largest unpaired electron density and also the site with (marginally) the higher affinity for hydrogen bonds. The hydrophilic character is almost completely lost upon oxidation of A^*- to A. Reduction to AH^- strengthens the hydrogen bonding of the depronated oxygen and weakens the hydrogen bonding of the protonated O atom.

Mots clés: Physical Sciences

Francesca Costanzo. Ab initio molecular dynamics study of ascorbic acid in aqueous solution. Molecular Physics, 2007, 105 (01), pp.17-23. ⟨10.1080/00268970601126718⟩. ⟨hal-00513064⟩