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Mobility of Small Molecules in Interlayers of Hectorite Gels: ESR Study with an Uncharged Spin Probe

Published online by Cambridge University Press:  28 February 2024

M. B. McBride
M. B. McBride*
Affiliation:
Cornell University, College of Agriculture and Life Sciences, Department of Soil, Crop and Atmospheric Sciences, 910 Bradfield Hall, Ithaca, New York 14853
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Abstract

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Electron spin resonance (ESR) spectroscopy was used to measure the rotational mobility of an uncharged nitroxide spin probe (4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy) in hectorite gels of variable water content. Physical adsorption segregated the probe molecules into two populations: probes in the solution or a solution-like phase, and motionally restricted probes in the adsorbed phase. Although the spectra of these two populations were discrete, indicating that exchange between them was slow on the time scale relevant to ESR, their overlap prevented a straightforward determination of mobility of the adsorbed probes. Even though adsorption was weak, effects of the adsorbed population on the spectral lineshape were detectable for suspensions containing as little as 20 grams clay per liter of water. Orientation of the adsorbed probes on the fully hydrated hectorite surfaces was similar to that of a positively charged nitroxide probe, suggesting that steric factors rather than electrostatic forces control short-range organic molecule interaction with the silicate. The possibility of reaching false conclusions about probe mobility and interlamellar water viscosity when using a weakly adsorbing probe is discussed.

Keywords

ESRHectoriteMolecular mobility
Type
Research Article
Information
Clays and Clay Minerals , Volume 42 , Issue 4 , August 1994 , pp. 455 - 461
Copyright
Copyright © 1994, Clay Minerals Society

References

Finch, E. D., and Harmon, J. F., (1974) Viscosity of cellular protoplasm: What do spin probes tell us?: Science 186, 157–158.CrossRefGoogle ScholarPubMed
Fripiat, J., Cases, J., Francois, M., and Letellier, M., (1982) Thermodynamic and microdynamic behavior of water in clay suspensions and gels: J. Colloid and Interface Science 89, 378–400.CrossRefGoogle Scholar
Israelachvili, J. N., and Adams, G. E., (1978) Measurement of forces between two mica surfaces in aqueous electrolyte solutions in the range 0–100 nm: J. Chem. Soc. Faraday Trans. 1, 74, 975–1001.CrossRefGoogle Scholar
Israelachvili, J. N., McGuiggan, P. M., and Homola, A. M., (1988) Dynamic properties of molecularly thin liquid films: Science 240, 189–190.CrossRefGoogle ScholarPubMed
Kemper, W. D., Maasland, D. E. L., and Porter, L. K., (1964) Mobility of water adjacent to mineral surfaces: Soil Sci. Soc. Amer. Proc. 28, 164–167.CrossRefGoogle Scholar
McBride, M. B., (1979) Mobility and reactions of VO2+ on hydrated smectite surfaces: Clays and Clay Minerals 27, 91–96.CrossRefGoogle Scholar
McBride, M. B., (1986) Paramagnetic probes of layer silicate surfaces: in Geochemical Processes at Mineral Surfaces, Davis, J. A., and Hayes, K. F., eds., American Chem. Soc. Washington, D.C., pp. 362–388.Google Scholar
McBride, M. B., Pinnavaia, T. J., and Mortland, M. M., (1975) Electron spin relaxation and the mobility of manganese (II) exchange ions in smectites: American Mineralogist 60, 66–72.Google Scholar
Nordio, P. L., (1976) General magnetic resonance theory: in Spin Labeling, Berliner, L. J., ed., Academic Press, New York, 5–52.CrossRefGoogle Scholar
Pashley, R. M., and Israelachvili, J. N., (1984) Molecular layering of water in thin films between mica surfaces and its relation to hydration forces: J. Colloid Interface Sci. 101, 511–523.CrossRefGoogle Scholar
Sachs, F., and Latorre, R., (1974) Cytoplasmic solvent structure of single barnacle muscle cells studied by electron spin resonance: Biophysical Journal 14, 316–326.CrossRefGoogle ScholarPubMed
Snipes, W., and Keith, A. D., (1974) “Comment on viscosity of cellular protoplasm: what do spin probes tell us?” Science 186, 158.CrossRefGoogle Scholar
Sposito, G., and Prost, R., (1982) Structure of water adsorbed on smectites: Chemical Reviews 82, 553–573.CrossRefGoogle Scholar
van der Marel, H. W., and Beutelspacher, H., (1976) Atlas of Infrared Spectroscopy of Clay Minerals and their Admixtures: Elsevier, New York.Google Scholar