Neutral vs zwitterionic glycine forms at the water/silica interface : structure, energies, and vibrational features from B3LYP periodic simulations
B3LYP periodic calculations with a triple-xi-polarized Gaussian basis set have been used to study adsorption of glycine on a hydroxylated silica surface (2.2 OH/nm2) model derived from the (001) surface of edingtonite. The simulation envisages glycine adsorbed either as a gas-phase molecule or when...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1992. - 24(2008), 24 vom: 16. Dez., Seite 14027-34 |
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| Weitere Verfasser: | , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2008
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| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article Research Support, Non-U.S. Gov't Water 059QF0KO0R Silicon Dioxide 7631-86-9 Glycine TE7660XO1C |
| Zusammenfassung: | B3LYP periodic calculations with a triple-xi-polarized Gaussian basis set have been used to study adsorption of glycine on a hydroxylated silica surface (2.2 OH/nm2) model derived from the (001) surface of edingtonite. The simulation envisages glycine adsorbed either as a gas-phase molecule or when microsolvated by up to five H20 molecules. Both neutral and zwitterionic forms of glycine have been considered and their structural, energetic, and spectroscopic vibrational features compared internally and with experiments. As a gas phase glycine sticks in its neutral form at the silica surface, the zwitterion being highly unstable and with transition-state character. When glycine is microsolvated at the silica interface, two H20 molecules render the zwitterion population comparable to that of the neutral form whereas with four H2O molecules the neutral glycine population is wiped out in favor of the zwitterion. With four H20 molecules the most stable structure shows no direct contact between glycine and the silica surface, H20 acting as a mediator via H-bond interactions. The B3LYP energies and structural data were also supported by comparing the scaled harmonic vibrational features with literature FTIR data of glycine adsorbed on an amorphous silica surface either from the gas phase or in water solution |
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| Beschreibung: | Date Completed 01.05.2009 Date Revised 21.11.2013 published: Print Citation Status MEDLINE |
| ISSN: | 1520-5827 |
| DOI: | 10.1021/la8029352 |