Heteronuclear Multible Bond Correlation Spectroscopy

1. HETERONUCLEAR MULTIBLE
BOND CORRELATION
SPECTROSCOPY
PRESENTING BY-
INDRAJIT SAMANTA
M.PHARM; 1STYEAR; 2ND SEMISTER
DEPARTMENTOF PHARMACEUTICAL
CHEMISTRY
SPER,JAMIA HAMDARD
SUBMITTEDTO-
Dr. M. SHAQIQUZZAMAN
PROFESSOR,
DEPARTMENTOF PHARMACEUTICAL
CHEMISTRY;
SPER, JAMIA HAMDARD

2. LIST OF CONTENTS:
INTRODUCTION
STRATEGIESTO SUPPRESS UNDESIRED ONE-BOND
CORRELATIONS
HMBC Experiments for Determining Coupling Constants
Extending the Scope of Long-range Coupling Constants
Examples

3. 2D-NMR classification
2D NMR
HOMONUCLEAR
CORRELATION
NOESY COSY ROESY TOCSY
HETERO NUCLEAR
CORRELATION

4. Continue..
HETERO NUCLEAR
CORRELATION
indirect
HMBC HMQC HSQC
direct
HETCOR
LR-
HETCOR

5. INTRODUCTION:
• The 1986 report of the proton-detected HMBC experiment by Bax and Summers .
• HMBC (Heteronuclear Multiple Bond Correlation) is a variant of the HMQC pulse
sequence that allows one to correlate X-nucleus shifts that are typically 2-4 bonds
away from a proton.
• HMBC (Heteronuclear Multiple Bond Correlation) spectroscopy is a modified
version of HMQC suitable for determining long-range 1H-13C connectivities.
• A highly resolved inverse detected heteronuclear correlation spectroscopy where plot
is between two dissimilar nuclei attached at longer distance(2 or 3 bonds couplings).
• Hence also quaternary carbon atoms will be detected.
• 1H,13C HMBC is frequently used for assigning of quaternary and carbonyl carbons and thus
connecting spin systems.
• You will see your 1H spectrum as your direct F2 axis and your 13C chemical
shifts as your indirect F1 axis.

6. STRATEGIESTO SUPPRESS UNDESIRED
ONE-BOND CORRELATIONS
The TANGO HMBC experiment: The one-bond correlations can be eliminated in a
single scan by inserting a basic TANGO excitation element with two p/4-pulses for
13C-bound 1H, followed by a ‘spoiler’ gradient before the HMBC pulse sequence In
this pulse sequence, chemical shift evolution during the gradient pulses in t1 and
immediately preceding acquisition causes large frequency-dependent phase shifts.
Therefore, these spectra are usually displayed in magnitude mode.
The BIRD-HMBC sequence: The basic BIRD-HMBC pulse sequence, which
implements efficient low-pass J-filtering and provides narrow line shapes in spite of
magnitude mode spectral display.
Clean HMBC

7. HMBC Experiments for Determining
Coupling Constants
 J-resolved HMBC
J-IMPEACH-MBC
IMPACT-HMBC
Determination of RDCs

8. Extending the Scope of Long-range
Coupling Constants
• ACCORD-HMBC
• CIGAR-HMBC
• ACCORD-BIRD-HMBC
• Broadband
• J-compensated HMBC

9. HMBC of ethyl (E)-but-2-enoate
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10. a
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19. REFERENCES:
• Wolfgang Schoefberger et al, Recent Developments in Heteronuclear Multiple-
Bond Correlation Experiments, Annual Reports on NMR Spectroscopy,Volume 72
,2011 Elsevier Ltd. ISSN 0066-4103, DOI: 10.1016/B978-0-12-385857-3.00001-3
• https://chem.libretexts.org/Ancillary_Materials/Worksheets/Spectroscopy_(Works
heets)/19%3A_HMBC#:~:text=HMBC%20
• https://emerypharma.com/blog/a-step-by-step-guide-to-1d-and-2d-nmr-
interpretation/
• Peyman Sakhai et al, Broadband homodecoupled heteronuclear multiple bond
correlation spectroscopy, 8 January 2013,
https://doi.org/10.1016/j.jmr.2012.12.018
• Y.Vasav et al, Heteronuclear Multible Bond Correlation Spectroscopy- An
Overview, ISSN : 0974-4304Vol.3, No.3,pp 1410-1422, July-Sept 2011