ODESSA, a New 1D NMR Exchange Experiment for Chemically Equivalent Nuclei in Rotating Solids

Recent Advances in Solid‐State MAS NMR Methodology for Probing Structure and Dynamics in Polymeric and Supramolecular Systems

“…Slow exchange can also be probed by one-dimensional analogues of the full two-dimensional 13 C exchange experiments. In the ODESSA (one-dimensional exchange spectroscopy by sideband alternation) experiment, [229] the redistribution of magnetisation within a particular sideband manifold due to molecular reorientation is monitored following the inversion of alternate sidebands during the preparation period. A time-reversed variant has been presented which overcomes the sideband phase distortions that occur with multiple reorienting sites.…”

Order–disorder phenomena in crystalline phases of compounds E(XMe3)4 where E = C, Si, Ge and X = Si, Sn

“…Mainly for reasons of signal-to-noise ratio achievable within reasonable amounts of spectrometer time, it may sometimes be preferable to perform 2D EXSY experiments not on a nonspinning sample, but on a slowly spinning sample (where`slow' is defined as considerably less than the spread of the chemical shielding tensor). Under slow-spinning MAS conditions, either one-dimensional MAS NMR experiments monitoring exchange amongst crystallographically equivalent sites 11,12 or 2D EXSY experiments may be performed; the latter then need to be performed in a rotation-synchronized manner. 19,20 We may now proceed and have a look at the results obtained by such solid-state NMR experiments in conjunction with high-resolution powder X-ray diffraction studies The effects of a two-site exchange amongst the`blue site' and the`red site' as depicted in a symbolic contour plot of a 2D EXSY experiment on a nonspinning powder sample.…”

“…The underlying exchange-matrix formalism is easily extended from the simple two-site case to more complicated cases where exchange amongst more sites occurs. Recording one-dimensional variable-temperature MAS NMR spectra for subsequent lineshape analysis obviously requires the exchange to take place amongst crystallographically inequivalent sites giving rise to spectrally resolved resonances in the slow-exchange limit (alternative MAS NMR experiments exist which permit monitoring chemical exchange amongst crystallographically equivalent sites via isolated spin-1/2 nuclei in one-dimensional experiments; 11,12 groups. It is not a trivial task to determine precisely the absolute temperature inside a spinning rotor, despite some existing calibration methods.…”

13C and 31P high resolution solid state NMR studies of cyclophosphamide and its analogues

“…1) are anticancer agents [1][2][3][4]. These compounds were studied in advance by X-ray crystallography [5][6][7][8][9][10][11][12][13], ODESSA experiment [14,15], and XRPD [16]. These oxazaphosphinanes are solid, so solid state NMR (SS NMR) study is very useful for them [17].…”