A Molecular Picture of the Adsorption of Glycine in Mesoporous Silica through NMR Experiments Combined with DFT‑D Calculations

Nicolas Folliet (1) , Christel Gervais (1) , Dominique Costa (2) , Guillaume Laurent (1) , Florence Babonneau (1) , Lorenzo Stievano (3) , Jean-François Lambert (4) , Frederik Tielens (4)

1 LCMCP - Laboratoire de Chimie de la Matière Condensée de Paris
2 LPCS - Laboratoire de Physico-Chimie des Surfaces
3 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
4 LRS - Laboratoire de Réactivité de Surface

The adsorption behavior of the amino acid glycine in mesoporous silica has been investigated using a combination of quantum chemical calculations and NMR spectroscopy experiments. Glycine adsorption on two representative sites of an amorphous silica surface, vicinal silanols and a silanol nest, was investigated by DFT-D. The effect of water coadsorption on the energetics of adsorption and NMR shifts was characterized. It was found that the silanol nest is a more favorable site for glycine adsorption due to a local increased H-bond density. Co-adsorption with water is also favored, especially a water molecule between a SiOH and the ammonium moiety. NMR chemical shifts computed on these models fall into the observed 13C and 15N experimental range, suggesting that the presence of different energetically comparable adsorption configurations cannot be excluded.

Domaines: Matériaux; Chimie théorique et/ou physique

Nicolas Folliet, Christel Gervais, Dominique Costa, Guillaume Laurent, Florence Babonneau, et al.. A Molecular Picture of the Adsorption of Glycine in Mesoporous Silica through NMR Experiments Combined with DFT‑D Calculations. Journal of Physical Chemistry C, 2013, 117, pp.4104-4114. ⟨10.1021/jp312195a⟩. ⟨hal-00797997⟩