The adsorption and reactions of the amino acid proline on rutile TiO2(110) surfaces

Adsorption of Proline and Glycine on the TiO2(110) Surface: A Density Functional Theory Study

“…The binding mode N(ON) converges to AN(ON). Experimental studies by Idriss et al [25] find indications for the anionic binding mode as most stable and estimate the binding energy to 110 kJ mol À1 in good agreement with the calculations presented here. Overall, the adsorption behavior of pro is very similar to gly, but zwitterionic structures seem to be less important.…”

“…For the (110) surface, both dissociative and zwitterionic adsorptions were found at 300 K. Upon heating, the zwitterionic species left the surface first, which indicates that the dissociative binding mode is the more stable one under these conditions. [25] Another study by Langel and Menken [27] focused on the interaction of amino acids with hydroxylated TiO 2 surfaces.…”

Probing the interaction of the amino acid alanine with the surface of ZnO

“…The interaction of these amino acids with TiO 2 surfaces has been found similar to that of carboxylic acids where binding occurs through the O atoms of the carboxylate function with two surface Ti atoms in a bridging configuration. In addition, evidence for a stable zwitterionic structure has been provided by the corresponding N1s XPS data [12,13]. On TiO 2 (1 1 0) experimental observations indicate that the zwitterionic structure is less stable than the anionic one.…”

“…Metal oxides have therefore been receiving increasing attention in the last few years with regard to biological systems. Examples of these studies include the investigation of proline adsorption on TiO 2 (1 1 0) and (0 1 1) single crystal surfaces by synchrotron XPS and TPD [11][12][13] and glycine on TiO 2 (1 1 0) single crystals by synchrotron UPS [14,15], by STM [16], and using plane wave DFT computation methods [17]. The interaction of these amino acids with TiO 2 surfaces has been found similar to that of carboxylic acids where binding occurs through the O atoms of the carboxylate function with two surface Ti atoms in a bridging configuration.…”

Adsorption structure of glycine on TiO2(1 1 0): A photoelectron diffraction determination

“…This interpretation was reinforced by their observation that the STM images showed no evidence of any asymmetry in the molecular features. An experimental investigation of proline, C 4 NH 8 COOH, on the stoichiometric TiO 2 (110) surface, using core-level photoemission [24,25], also indicates that both zwitterionic and dissociated (deprotonated) forms are present on the surface, but with the zwitterion desorbing at a lower temperature. Combined with the earlier results on glycine adsorption, the experiments therefore indicate that the preferred form of these adsorbed amino acids on TiO 2 (110) is the deprotonated form, with zwitterionic material being present only at higher coverages, particularly in multilayer films.…”