Solute-solvent interactions in perfluorocarbon solutions of oxygen. An NMR study

Abstract

Fluorinated compounds, including alkanes, alkenes, aromatics, amines, and cyclic and heterocyclic fluorochemicals, are studied as solvents of oxygen, using for this purpose the paramagnetic relaxation induced by the presence of molecular oxygen onto the I3C nuclei of neighboring solvent molecules in the solution. Relaxation data are expressed by the variation rates qx of relaxation rates TI-' per mole fraction of dissolved oxygen. A general correlation is found between the solubility of oxygen (in mole fraction) and the relaxation coefficients qx, the lower qx values being associated to the higher solubilities. This was accounted for by the existence of large cavities in the liquid for the better solvents, which can thus accommodate small gaseous molecules more easily, while simultaneously the magnetic dipolar interaction between oxygen and solvent nuclei is decreased. The sequence found for compounds of decreasing solubility, aliphatic > cyclic > aromatic, can be rationalized on the basis of cavities of decreasing size from one class of solvents to the other. The order of solubility seems to depend mainly upon the shape of solvent molecules and not upon the details of molecular structure, thus discarding the alternative assumption of specific fluorine-oxygen forces and of a possible charge-transfer complex. The higher relaxation coefficients obtained for some typical analogous hydrocarbons can be rationalized by using the same concepts.

Molecular Imaging of Hypoxia

“…Measurements are possible from anoxia to hyperbaric conditions, although the best precision is generally obtained below 10 mm Hg (166,167). This approach is conceptually different from the use of nitroimidazoles, which react chemically, leading to trapped adducts in hypoxic environments.…”

Rotational Motion of a Solute Molecule in a Highly Viscous Liquid Studied by13C NMR: 1,3-Dibromoadamantane in Polymeric Chlorotrifluoroethene

“…s 01 (see Table 1). It is known that fluorinated organic compounds have exDecoupling of the 19 F spins of the solvent by strong RF [7] 50,000 …”

“…However, a small contribution of 19 F to other if a Lorentzian spectral density is assumed. This is dipolar T 1 and T 2 relaxation of 13 C, not exceeding a few illustrated in Fig.…”

“…ceptional abilities to dissolve oxygen (18,19), which could cause paramagnetic relaxation of guest molecules. Therefore, the polymeric oil was degassed under high vacuum and handled in an argon atmosphere.…”

Vatuximab(Trademark): Optimizing Therapeutic Strategies for Prostate Cancer Based on Dynamic MR Tumor Oximetry

“…The solubility of oxygen (and gases in general) in perfluorocarbons and hydrofluorocarbons is three to ten times higher than observed in the parent hydrocarbons or in water (101,102). It was shown that a model of continuous diffusion of oxygen, that accounts for the T 1 and T 2 relaxation of benzene, fails in the case of HFB, leading to either impossibly short residence times for oxygen or impossibly small distance of closest approach between fluorine and oxygen (93).…”