Heteronuclear Multible Bond Correlation Spectroscopy.pptx

Heteronuclear Multible Bond Correlation Spectroscopy

1. HETERONUCLEAR MULTIBLE BOND CORRELATION SPECTROSCOPY PRESENTING BY- INDRAJIT SAMANTA M.PHARM; 1ST YEAR; 2ND SEMISTER DEPARTMENT OF PHARMACEUTICAL CHEMISTRY SPER,JAMIA HAMDARD ​ SUBMITTED TO- Dr. M. SHAQIQUZZAMAN PROFESSOR, DEPARTMENT OF PHARMACEUTICAL CHEMISTRY; SPER, JAMIA HAMDARD

2. LIST OF CONTENTS:

3. 2D-NMR classifica tion

4. Continue..

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 ( H eteronuclear M ultiple B ond C orrelation) spectroscopy is a modified version of HMQC suitable for determining long-range 1 H- 13 C 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. 1 H, 13 C HMBC is frequently used for assigning of quaternary and carbonyl carbons and thus connecting spin systems. You will see your 1 H spectrum as your direct F2 axis and your 13 C chemical shifts as your indirect F1 axis.

6. STRATEGIES TO 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 13 C-bound 1 H, 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

11. 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_(Worksheets)/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 : 0974-4304 Vol.3, No.3,pp 1410-1422, July-Sept 2011