Canonical, Deprotonated, or Zwitterionic? A Computational Study on Amino Acid Interaction with the TiO2 (101) Anatase Surface

Abstract

The interaction of 11 amino acids with the TiO2 (101) anatase surface was investigated by means of PBE-D2* periodic simulations, both from a static and dynamic points of view. Several adsorption states, with the amino acid in its canonical, zwitterionic, or deprotonated forms, were considered. The strongest interactions correspond to dative interactions between the electron pairs of N or O atoms of the amino acids and the Ti atoms of the surface. For glycine, the most stable configuration corresponds to the deprotonated (N,O) binding mode, at variance to that observed for the adsorption of glycine on rutile (110) surface, for which the dissociative (O,O) binding mode was determined to be the preferred one. For the remaining amino acids, the following general trend was identified: those amino acids with acidic or a basic lateral chain groups, except Arg, exhibit a deprotonated (N,O) binding mode as glycine, because the additional dative interactions with the side chain overcome the destabilizing effect ind...