This document presents an overview of heteronuclear multiple bond correlation (HMBC) spectroscopy. HMBC allows the detection of long-range couplings between protons and carbon atoms that are 2-4 bonds apart. Various experiments are discussed to suppress undesired one-bond correlations and determine long-range coupling constants. Examples of applying HMBC to determine connectivity in molecules like ethyl butenoate are also provided. The document concludes with references for further reading on developments in HMBC experiments.

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
f
a
e
c
b
d
f
a
e
c
b

10. a
b
c
d
e
a
b
c
d
e
f

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