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17 O NMR spectroscopy: Referencing in diamagnetic and paramagnetic solutions
Author(s) -
Gerothanassis Ioannis P.,
Lauterwein Jürgen
Publication year - 1986
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260241205
Subject(s) - diamagnetism , chemistry , nitromethane , paramagnetism , chemical shift , nuclear magnetic resonance spectroscopy , nuclear magnetic resonance , solvent , analytical chemistry (journal) , gadolinium , stereochemistry , magnetic field , condensed matter physics , organic chemistry , physics , quantum mechanics
Several referencing techniques for measuring 17 O NMR chemical shifts in diamagnetic and paramagnetic solutions have been examined. 1,4‐Dioxane is recommended as an external reference standard for diamagnetic solutions because the 17 O resonance position is independent of temperature between 27 and 90°C. At 40°C the 17 O chemical shift, within experimental error, corresponds to that of doubly distilled water. Nitromethane cannot be considered as a suitable internal reference because of large solvent effects on the 17 O chemical shift. Further, in organic solutions its lanthanide‐induced chemical shifts are not negligible. For the study of paramagnetic solutions the combined use of a cylindrical and a spherical cell is proposed: the 17 O resonance of either the magnetically active solvent or a convenient compound added to the solution is recorded in both cells; the chemical shift difference between the two measurements is the bulk magnetic susceptibility shift.