Skip to main content
Chemistry LibreTexts

2D NMR: Indirect Detection

The advantages of the indirect detection

The reverse detection technique became increasingly popular due to the software improvements of the spectrometers from one hand and to the increase of the sensitivity of the detection of a X nucleus by the indirect way. In fact the reverse detection solves the problem of the low concentrations. Moreover, it allows to reach the NMR parameters such as chemical shifts, coupling constants and relaxation time spin lattice for nuclei impossible to study by the direct detection (Fig. 28).

For example it is not always obvious to get NMR spectra for nuclei such as 57Fe, 183W, 187Os and sometimes even 15N in direct observation. Consequently, the reverse detection becomes the only possible way either for 1H-15N correlation in the case of peptides or proteins or also for 1H-X correlation in the case of organometallic compounds. In each of these examples the reverse detection allowed to determine the chemical shift of the heteronucleus together with the coupling constants J(X-H).

Fig. 28: Scheme for a reverse detection pulse sequence.

The arrows figure the magnetization transfer from the proton towards the 13C and then from the 13C towards the proton.

The available pulse sequences

The HSQC (Heteronuclear Single Quantum Coherence) is specially used for the structural determination of small proteins. The HMBC (Heteronuclear Multiple Bond Coherence) is optimized for long range couplings and works better than a COLOC.

Bibliography

  1. La détection inverse en RMN ; M Boudonneu Analusis N°1, vol.18, 1990
  2. La RMN concepts et méthodes; D. Canet inter éditions 1991
  3. La spectroscope de RMN, H. Gunther MASSON 1994.
  4. NMR in protein studies. M. P. Williamson. Chem. in Britain April 1991(335-337).
  5. RMN 2D BRUKER 1993 Poly. 1, 2 et 3.
  6. Resonance Magnétique Nucléaire; Evolution instrumentale et analyse de structure; J.P. Girault le technoscope de biofutur n°38 sept 90
  7. Sensitivity enhancement by signal averaging in pulsed by Fourier transform NMR spectroscopy; D. L.Rabenteck; J. of Chem. Ed. Vol. 61, n°70, Oct 1984
  8. Sequence Cosy Poly. BRUKER 1993.
  9. Topic in chemical instrumentation part 3 and 4. 2 D Methods W. King and K. R. Williams J. of Chem. Educ. vol.67n°4.
  10. Topics in chemical instrumentation (Definition) W. King and K. R. Williams
  11. Two Dimensional NMR spectroscopy; Applications for chemists and biochemists; W. R. Crousmum, R. M. K. Carlson. Vol 9.
  12. Two dimensional NMR Aspect 2000 - 3000 BRUKER
  13. G. E. Reeman et Moms, J. ChemSoc, Chem.Comm, 684 (1978).
  14. H. Kessler, W. Bernel and C. Giresinger, J. AM. Chem. Soc. 107, 1083 (1985).

Contributors

Template:Bria