Nuclear magnetic resonance studies of the interaction of molecular oxygen with organic compounds

Abstract

Proton nmr line broadenings and chemical shifts due to dissolved molecular oxygen were measured for various organic compounds. After corrections for the extra broadening in spin-spin multiplets, due to 7\ spin decoupling effects, the observed oxygen-induced broadening was similar for all compounds studied. It was concluded that there was no complex formation between the oxygen and the organic molecules. Small oxygen-induced chemical shifts could be observed and some possibilities for their origin were discussed.

Determination of Oxygen Permeability in Acrylic‐Based Hydrogels by Proton NMR Spectroscopy and Imaging

“…The presence of oxygen lead to a slight broadening of the water resonance, changing the full‐width at half‐height from 12 to 15 Hz in the absence of oxygen to ≈45 Hz after loading O 2 . Small line broadening and displacements of chemical shifts in the proton spectra of organic solvents due to dissolved oxygen have been observed . Thus, to calculate proton T 1 s, water peak areas were used.…”

“…Small line broadening and displacements of chemical shifts in the proton spectra of organic solvents due to dissolved oxygen have been observed. [ 69 ] Thus, to calculate proton T 1 s, water peak areas were used. In all cases, the observed behavior of the inversion-recovery data was monoexponential and their fi ts to Equation 9 lead to values of T 1 with standard deviations varying between 7 and 12 ms.…”

“…However, the fact that O 2 is paramagnetic causes a reduction of the relaxation times of other nuclei when the gas is present in the sample, due to electron–nuclear dipolar interactions. This phenomenon has been known since the earlier days of NMR and was a problem for the study of relaxation times in fluids and other types of samples …”

“…This phenomenon has been known since the earlier days of NMR and was a problem for the study of relaxation times in fl uids and other types of samples. [41][42][43] Consequently, the paramagnetic effect of oxygen upon relaxation times in fl uids has been widely studied and its measurement has been used to determine the solubility of oxygen in, i.e., aqueous media and fl uorocarbons. [44][45][46][47] Concerning this work, we are interested in the application of NMR to determine the solubility and diffusion coeffi cients of oxygen in hydrogels.…”