Surface solvation and hindered isomerization at the water/silica interface explored with second harmonic generation.
J Chem Phys
; 150(19): 194701, 2019 May 21.
Article
en En
| MEDLINE
| ID: mdl-31117767
ABSTRACT
Resonantly enhanced second harmonic generation (SHG) spectra of Coumarin 152 (C152) adsorbed at the water-silica interface show that C152 experiences a local dielectric environment slightly more polar than that of bulk water. This result stands in contrast to recently reported time-resolved fluorescence experiments and simulations that suggest an alkane-like permittivity for interfacial water at strongly associating, hydrophilic solid surfaces. Taken together, these results imply that while the static electric field across the aqueous-silica interface may be large, restricted water dynamics lead to apparent nonpolar solvation behavior similar to that experienced by solutes in confinement. Resonance-enhanced SHG spectra and time-resolved fluorescence of C152 adsorbed to aqueous-hydrophobic silica surfaces show that when water's ability to hydrogen bond with the silica surface is eliminated, a solute's interfacial solvation and corresponding ability to photoisomerize converge to an intermediate limit similar to that experienced in bulk acetone or methanol. While water structure and dynamics at solid-liquid interfaces have received considerable attention, results presented below show how strong solvent-substrate interactions can create conflicting pictures of solute reactivity across buried interfaces.
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1
Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
J Chem Phys
Año:
2019
Tipo del documento:
Article
País de afiliación:
Estados Unidos