Hidden Isolated OH at the Charged Hydrophobic Interface Revealed by Two-Dimensional Heterodyne-Detected VSFG Spectroscopy.
Angew Chem Int Ed Engl
; 59(24): 9498-9505, 2020 06 08.
Article
em En
| MEDLINE
| ID: mdl-32189396
ABSTRACT
Water around hydrophobic groups mediates hydrophobic interactions that play key roles in many chemical and biological processes. Thus, the molecular-level elucidation of the properties of water in the vicinity of hydrophobic groups is important. We report on the structure and dynamics of water at two oppositely charged hydrophobic ion/water interfaces, that is, the tetraphenylborate-ion (TPB- )/water and tetraphenylarsonium-ion (TPA+ )/water interfaces, which are clarified by two-dimensional heterodyne-detected vibrational sum-frequency generation (2D HD-VSFG) spectroscopy. The obtained 2D HD-VSFG spectra of the anionic TPB- interface reveal the existence of distinct π-hydrogen bonded OH groups in addition to the usual hydrogen-bonded OH groups, which are hidden in the steady-state spectrum. In contrast, 2D HD-VSFG spectra of the cationic TPA+ interface only show the presence of usual hydrogen-bonded OH groups. The present study demonstrates that the sign of the interfacial charge governs the structure and dynamics of water molecules that face the hydrophobic region.
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Coleções:
01-internacional
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MEDLINE
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article