H2BC

Heteronuclear 2-bond correlations: A two-dimensional NMR pulse sequence for long-range correlation of 1H and 13C nuclei. The experiment has several attractive features compared to the widely used HMBC experiment

  • typically strong enhancement of correlations over two bonds while suppressing those over more bonds
  • independence of long-range 1H-13C coupling constants,
  • full homo- and heteronuclear decoupling in the indirect dimension and heteronuclear decoupling in the acquisition dimension,
  • pure 2D absorption peak shapes,
  • a pulse sequence duration significantly shorter than that of HMBC.

The experiment is quite complementary to HMBC and does not effect correlations to quaternary carbons that must be obtained by HMBC.

Sequence

Pulse sequence H2BC with a 3rd order low-pass J filter for correlating 1H and 13C nuclei via 1JCH and 1H-1H couplings. Filled and open bars refer to pi /2 and pi pulses, respectively, while the dashed boxes represent 13C decoupling.

  • tau 1 = ½ [1Jmin + 0.07(1Jmax - 1Jmin)]-1
  • tau = tau 2 = [1Jmax + 1Jmin]-1
  • tau 3 = ½ [1Jmax - 0.07(1J max - 1Jmin)]-1
  • delta ' = delta + t( pi H) where delta is the gradient delay.

T denotes the constant-time delay. The gradient strength G1 is G and -G for echo and antiecho selection, respectively.

The recommended phase cycle is

  • phi 1 = {x, -x, -x, x},
  • phi 2 = {x, x, 4(-x), x, x},
  • phi 3 = {4(x), 4(y), 4(-x), 4(-y)}
  • Receiver phase {x, -x}.

Animation

Have a look at a animation showing the evolution of the t1 delay.

Results

H2BC-spectrum of Strychnine H2BC (red) and HSQC spectrum (green) of strychnine dissolved in CDCl3. Recorded on a 600 MHz spectrometer with 3rd order low-pass J filters set for the range 125 Hz < 1J < 170 Hz, T = 21.9 ms and relaxation delay 2 seconds. The inserted lines connect signals in the HSQC spectrum with the two bond correlations in the H2BC spectrum, thereby tracing connections from carbon 11 and 8, via 13, to 16 and between 17 and 18.
Strychnine Strychnine

Poster

Download the H2BC-poster that won 'best poster award' at SMASH 2005 in Verona, Italy.

References

  1. Nils T. Nyberg, Jens Ø. Duus, Ole W. Sørensen Heteronuclear 2-Bond Correlation: Suppressing Heteronuclear Three-Bond or Higher NMR Correlations while Enhancing Two-Bond Correlations Even for Vanishing 2JCH J. Am. Chem. Soc. 127 6154-6155 2005

  2. Nils T. Nyberg, Jens Ø. Duus, Ole W. Sørensen Editing of H2BC NMR spectra Magnetic Resonance in Chemistry 43 971-974 2005

  3. Bent O. Petersen, Evguenii Vinogradov, William Kay, Peter Würtz, Nils T. Nyberg, Jens Ø Duus, and Ole W. Sørensen H2BC: A new technique for NMR analysis of complex carbohydrates Carbohydrate Research 341 550-556 2006

Code and procedures

For Bruker.

For Varian, please use the code and procedures for the edited H2BC.

 
Document: H2BC (index.shtml)
Last modified: 2006-03-17