MBOB: Multiple-Bond and One-Bond Correlation

Without any compromise in HMBC sensitivity MBOB allows edited 2D Broadband HMBC and one-bond correlation spectra to be extracted from the same dataset.

The merits of MBOB are:

• Uniform excitation over a range of long-range XH coupling constants.
• The time it would normally take to record an HSQC or HMQC spectrum is saved. Read NMR Newsletter note

Sequence

_i = duration of low-pass J filter (LPJF),
_F = low pass J filter delay.

• 1^st order LPJF:
  • _F = {0, ₁}
  • ₁=(J^max + J^min)^-1
• 2^nd order LPJF:
  • _F = { 0, ₁, ₂, ₁+ ₂ }
  • ₁ = ( 2×(J^min + 0.146(J^max - J^min)))^-1
  • ₂ = ( 2×(J^max - 0.146(J^max - J^min)))^-1
• 3^rd order LPJF:
  • _F = { 0, ₁, ₂, ₃, ₁ + ₂, ₁ + ₃, ₂ + ₃, ₁ + ₂ + ₃ }
  • ₁ = ( 2×(J^min + 0.070(J^max - J^min)))^-1
  • ₂ = ( J^max + J^min)^-1
  • ₃ = ( 2×(J^max - 0.070(J^max - J^min)))^-1

= excitation delay.

= gradient delay

Gradient ratios:

• +5.0 : -3.0 for echo
• -3.0 : +5.0 for antiecho

Results

Expansion of a conventional = 65 ms 2^nd order LPJF HMBC spectra of 15 µl of ethyl trans-cinnamate in 600 µl CDCl₃ at 25° C.

References

• Meissner, A. and Sorensen, O.W. Economizing spectrometer time and broadband excitation in small-molecule heteronuclear NMR correlation spectroscopy. Broadband HMBC Magn.Reson.Chem. 38 981-984 2000


• Schulte-Herbrüggen, T., Meissner, A., Papanikos, A., Meldal, M., and Sorensen, O.W. Optimizing delays in the MBOB, broadband HMBC, and broadband XLOC NMR pulse sequences J.Magn.Reson. 156 282-294 2002

Code and procedures

For Varian and Bruker.