Do probe molecules influence water in confinement?
| Autor: | Nancy E. Levinger, Laura A. Swafford, Bharat Baruah, Debbie C. Crans |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Magnetic Resonance Spectroscopy
Spectrophotometry Infrared Inorganic chemistry Molecular Conformation Infrared spectroscopy Electrons Micelle Materials Chemistry Molecule Physical and Theoretical Chemistry Micelles Ions Aqueous solution Chemistry Chemistry Physical Chemical shift Water Hydrogen Bonding Vanadium Signal lines Tungsten Compounds Surfaces Coatings and Films NMR spectra database Models Chemical Chemical physics Molecular Probes Polyoxometalate Solvents Protons |
| Zdroj: | The journal of physical chemistry. B. 112(33) |
| ISSN: | 1520-6106 |
| Popis: | The water inside reverse micelles can differ dramatically from bulk water. Some changes in properties can be attributed to the interaction of water molecules with the micellar interface, forming a layer of shell water inside the reverse micelle. The work reported here monitors changes in intramicellar water through chemical shifts and signal line widths in 51V NMR spectra of a large polyoxometalate probe, decavanadate, and from infrared spectroscopy of isotopically labeled water, to obtain information on the water in the water pool in AOT reverse micelles formed in isooctane. The studies reveal several things about the reverse micellar water pool. First, in agreement with our previous measurements, the proton equilibrium of the decavanadate solubilized within the reverse micelles differs from that in bulk aqueous solution, indicating a more basic environment compared to the starting stock solutions from which the reverse micelles were formed. Below a certain size, reverse micelles do not form when the polyoxometalate is present; this indicates that the polyanionic probe requires a layer of water to solvate it in addition to the water that solvates the surfactant headgroups. Finally, the polyoxometalate probe appears to perturb the water hydrogen-bonding network in a fashion similar to that in the interior surface of the reverse micelles. These measurements demonstrate the dramatic differences possible for water environments in confined spaces. |
| Databáze: | OpenAIRE |
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