Experimental access to HSQC spectra decoupled in all frequency dimensions

Pure Shift 1H NMR: A Resolution of the Resolution Problem?

“…Many existing NMR techniques can be adapted to use pure shift acquisition; Zangger and Sterks original paper [7] described pure shift TOCSY, and very recently a pure shift HSQC based on Pines BIRD method [3] has been published. [12] Early pure shift DOSY experiments [9] used a stimulated echo sequence; here we show the results of applying the Oneshot-based [15,16] sequence of Figure 2 b to a mixture containing the partial-cone and cone calix [4]arenes of Scheme 1 at 2.0 and 2.6 mm and the parent, unsubstituted, calixarene at 6.8 mm. Figure 3 shows that pure shift DOSY allows complete resolution of the substituted from the unsubstituted calixarenes, which differ in diffusion coefficient by 9 %; signal overlap prevents such a resolution in a normal Oneshot experiment.…”

Simultaneously Enhancing Spectral Resolution and Sensitivity in Heteronuclear Correlation NMR Spectroscopy

“…[27] Here, the combined effect of the BIRD sequence and the hard 1808 pulse is to invert only those protons not directly coupled to 13 C, thus refocusing the effects of couplings between the latter protons and protons that are directly coupled (bonded) to 13 C and whose signals are recorded in HSQC. The great advantage of the BIRD method here is that, in contrast to Zangger-Sterk type methods, [8,9,22,23] it incurs no extra sensitivity penalty; indeed, the sensitivity is generally increased.The BIRD sequence element has already been very effectively used to obtain pure shift 1 H-13 C HSQC spectra, [16] and pure shift 1D proton spectra of strongly coupled …”

“…The BIRD sequence element has already been very effectively used to obtain pure shift 1 H-13 C HSQC spectra, [16] and pure shift 1D proton spectra of strongly coupled…”

“…It is routine to suppress heteronuclear couplings (J XH ) by broadband decoupling, [3][4][5][6][7] but only recently have experimental methods for homonuclear broadband decoupling become practical. These "pure shift" or "chemical-shift resolved" or "d-resolved" methods [8][9][10][11][12][13][14][15][16][17][18][19] can give resolution improvements approaching an order of magnitude, far in excess of any gains to be realistically expected from increases in the static magnetic field. However, all of these methods suffer to a greater or lesser extent from reduced sensitivity compared to conventional measurements.…”

“…The BIRD sequence element has already been very effectively used to obtain pure shift 1 H-13 C HSQC spectra, [16] and pure shift 1D proton spectra of strongly coupled species. [12] In both cases, the pure shift dimension was constructed from multiple separate acquisitions of short chunks of data, requiring ancillary software for the generation of decoupled spectra.…”