Spin probing hydrogen-bonding probes

I). We interpret the cholesterol-induced increase in hydrogen bonding below Tc (Figure 3A) as being due to an opening of the bilayer which allows more solvent to penetrate. Similar conclusions were reached from studies of doxyl stearic acid spin probes in frozen lipid vesicles... 

Hydrophilic spin probe 4-Oxo- TEMPO (Sigma) of 0.1 mM concentration was introduced in water dispersions of ShC nanoparticles of different concentrations (0.1, 1.0 and 10 mg/ml). Paramagnetic spin probe like TEMPOL effectively dissolves in hydration water [7,8] owing to capability of polar and paramagnetic NO group of probe to form hydrogen bonds with water molecules. 

I.S. Chuang, and G.E. Maciel, Probing Hydrogen Bonding and the Local Environment of Silanols on Silica Surfaces via Nuclear Spin Cross Polarization Dynamics, J. Am. Chem Soc., 118, pp. 401-406, 1996. 

For characterizing supramolecular interactions, it is of interest that g tensor principal values are sensitive to the polarity of the environment and are influenced by hydrogen bonding to an atom with significant spin density in a p orbital.For nitroxide spin probes, it was demonstrated that the two effects can be separated by correlating g,v.i to... 

Pace. M.D. Snow. A.W. Nitroxide spin-probe label of hydrogen-bonding and probe size effects in a linear epoxy polymer. Macromolecules 1995. 28 (15), 5300-5305. Starodoubtsev. S.G. Ryabova. A.A. Dembo, A.T. Dembo. K.A. Aliev, I.I. Wasserman, A.M. Khokhlov, A.R. Composite gels of poly(acrylamide) with incorporated bentonite. Interaction with cationic surfactants. ESR and SAXS study. Macromolecules 2002. 35 (16). 6362-6369. 

Chuang, I.-S. and Maciel, G.E. 1996. Probing hydrogen bonding and the local environment of silanols on silica surfaces via nuclear spin cross polarization dynamics. J. Am. Chem. Soc. 118 401-406. 

Recent work has demonstrated that spin probes can be incorporated into complex materials and used as local reporters of the polymer host. By a judicious choice of the polarity, size, and chemical structure of the probe, it is possible to explore specific regions of microphase-separated or self-assembled system, thus by-passing the often difficult synthetic procedures of preparing covalently bound spin labels. The site selected by the probes is based on the very same weak inter-molecular interactions (electrostatic, hydrogen bonding, metal coordination) that... 

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