Nuclear magnetic resonance (NMR) spectroscopy uses radio waves to determine molecular structure by analyzing the magnetic properties of atomic nuclei. It works by placing a sample in a strong magnetic field, which causes the magnetic nuclei in the sample to absorb and emit radio signals. Analyzing these signals provides information on the molecular structure, such as identifying carbon-hydrogen frameworks in organic molecules. NMR is used in fields like organic chemistry, biochemistry, and medical research to study molecular structure and interactions.

1. Nuclear Magnetic Resonance
SPECTROSCOPY
Submitted By:-
Juhi Verma
M.Sc -Iyr

2. Nuclear Magnetic Resonance
SPECTROSCOPY
Nuclear Magnetic Resonance Spectroscopy, or “NMR,” is a process
used to find out information about a compound’s magnetic
properties. It does so by recording the magnetic spectral patterns
given off by the nuclei within a sample’s atoms. Using NMR,
researchers can determine the molecular structure of a
compound.
Nuclear magnetic resonance spectroscopy(NMR) is a powerful
analytical technique used to characterize organic molecules by
identifying carbon-hydrogen frameworks within molecules.
It is a research technique that exploits the magnetic properties of
certain atomic nuclei.
It determines the physical and chemical properties of atoms or the
molecules in which they are contained.

3. Nuclear magnetic resonance spectroscopy is a spectroscopy
technique which based on electromagnetic radiation in the radio
frequency region 4 - 900MHz by nuclei of the atom
It is used to study wide variety of nuclei :-
1H ,19F, 13C, , 31P,15N
Only nuclei that contain odd mass numbers (such as 1H, 13C, 19F
and 31P) or odd atomic numbers (such as 2H and 14N) give rise to
NMR signals
In many atoms (such as 12C) these spins are paired against each
other, such that the nucleus of the atom has no overall spin.
However, in some atoms (such as 1H and 13C) the nucleus does
possess an overall spin

4. History
First described and measured by Isidor Rabi in 1938
In 1946, Felix Bloch & Edward Mills Purcell
refined the technique for use on liquids & solids
for which they shared the Nobel Prize in physics
in 1952.

5. Types of NMR
Two common types of NMR spectroscopy
are used to characterize organic structure:
• 1H NMR:- Used to determine the type and
number of H atoms in a molecule
• 13CNMR:- Used to determine the type of
carbon atoms in the molecule

6. Source of NMR
• The source of energy in NMR is radio
waves which have long wavelengths having
more than 10power 7nm, and thus low energy
and frequency.
• When low-energy radio waves interact with a
molecule, they can change the nuclear spins
of some elements, including 1H and 13C.

7. Type of Samples
Both liquid and solid type of samples can be used in NMR
spectroscopy.
In solid-phase media, samples like crystals, microcrystalline
powders, gels, anisotropic solutions, proteins, protein
fibrils or all kinds of polymers etc. can be used.
In liquid phase, different types of liquid solutions, nucleic
acid, protein, carbohydrates etc. can be used.
The sample is dissolved in a solvent, usually CDCl3(deutero-
chloroform), and placed in a magnetic field.

8. Effect of Magnetic Field
• When a charged particle such as a proton spins on its axis, it creates a
magnetic field. Thus, the nucleus can be considered to be a tiny bar
magnet.
• Normally, these tiny bar magnets are randomly oriented in space.
However, in the presence of a magnetic field B0, they are oriented with
or against this applied field.
• In a magnetic field, there are two energy states for a proton: a lower
energy state with the nucleus aligned in the same direction as Bo, and a
higher energy state in which the nucleus aligned against Bo.
• When an external energy source that matches the energy difference
between these two states is applied, energy is absorbed, causing the
nucleus to “spin flip” from one orientation to another
• A nucleus is in resonance when it absorbs RF radiation and “spin flips”
to a higher energy state. Thus, two variables characterize NMR: an
applied magnetic field B0, the strength of which is measured in tesla
(T), and the frequency n of radiation used for resonance, measured in
hertz (Hz), or megahertz (MHz).

9. Principle of NMR

11. Nuclear spin and the splitting of energy levels in a magnetic field
The rules for determining the net spin of a nucleus are as follows;
• If the number of neutrons and the number of protons are both even,
then the nucleus has NO spin.
• If the number of neutrons plus the number of protons is odd, then the
nucleus has a half-integer spin (i.e. 1/2, 3/2, 5/2)
• If the number of neutrons and the number of protons are both odd,
then the nucleus has an integer spin (i.e. 1, 2, 3)
The overall spin, I, is important. Quantum mechanics tells us that a
nucleus of spin I will have 2I + 1 possible orientations. A nucleus with
spin 1/2 will have 2 possible orientations. In the absence of an external
magnetic field, these orientations are of equal energy. If a magnetic
field is applied, then the energy levels split. Each level is given a
magnetic quantum number, m.

13. Chemical Shift
Chemical shift is seperation of spectral signal of H atom in
different chemical environment from that of a reference
compound.Its determine position of signals
TMS is the most common reference compound in NMR

14. • SHEILDING OF PROTONS
• High Electron density around a nucleus shields
nucleus from the external magnetic field and the
signals are upfield in the NMR spectrum
• deSHEILDING OF PROTONS
• Low Electron density around a nucleus deshields
nucleus from the external magnetic field and the
signals are downfield in the NMR spectrum

15. NMR Patterns
Interpreting NMR Signals:
• The number of signals will reflect the number of
equivalent (“like”) protons
• The intensity or size of the signal will infer a ratio of that
specific type of proton
• The position of the signal will infer “chemical shift,”
where the position of the peak in the NMR spectrum will
indicate how de-shielded or shielded the proton is
• Signal Splitting will be represented by the number of
peaks/lines that a proton signal will split into depending
on the other proton neighbors.

17. Factors affecting chemical shift
• Electronegative groups
• Magnetic anisotropy of  systems
• Hydrogen bonding

18. The interaction between the spins of proton with
that of another proton on adjacent carbon in a
molecule may cause the splitting of NMR
spectrum.This is known as Spin-Spin Coupling
or Splitting
The distance between the peaks in a given multiplet
in a measure of the magnitude of splitting effect.
It is referred to as Coupling constant and is
denoted by the symbol J. Numerical value of J is
expressed in Hz
Spin-Spin Coupling

19. Rules for Spin-Spin Coupling
• Chemically equivalent protons do not show
spin-spin coupling
• Only non equivalent protons couple
• Protons on adjacent carbon normally will
couple
• Protons seperated by four or more will not
couple

20. N+1 rule
• The multiplicty of signal is calculated by using n+1
rule
• This is one of the rule to predict the splitting of
proton signals.This is considered by the hydrogen
nuclei
Therefore n=Number of protons in nearby nuclei
• Zero H atom as neighbour n+1=0+1=1(singlet)
• One H atom as neighbour n+1=1+1=2(doublet)
• Two H atom as neighbour n+1=2+1=3(triplet)

21. Schematic Diagramof NMR

22. Applicatios of NMR in biology
• NMR is fundamental for determining and exploring the structure of
proteins, e.g. enzymes, receptors. It has been used to elucidate the
structure and function of numerous biological components.
• In determination of the structure of the CMAT receptor (an oncogene
that is involved in cancer metastasis) has allowed a variant to be
engineered that has an antagonistic effect.
• NMR thus plays a key role in the development of vaccines and
treatments for a range of diseases, including HIV, influenza,
tuberculosis and cancer, by allowing researchers to understand how
the disease-causing agents function and to identify potential drug
targets.
• NMR also provides a powerful tool for studying conformational
changes in proteins and chemical kinetic processes, which enables the
mode of action of enzymes, transporter proteins etc to be elucidated at
a molecular level.

23. • The development of technology, a huge number of low molecular weight
compounds have been synthesized by the chemists and a large number of
biological targets have been characterized by the biologist. These
compounds and their derivatives are the potential drug
• NMR help in study of metabolites Metabolites are the intermediates or
final products of different biochemical reactions happening in a biological
system. Metabolomics is a subset discipline of systems biology where the
metabolites from a specific biological system are assessed, identified and
quantified to gain information about the functional state of that biological
system. Theoretically, it can be used as an early diagnostic tool for
diseases. The malfunction of the biological system will cause a disorder in
the metabolites
• NMR is being used to characterise the transition of proteins in the brain
and to investigate the influence of such changes on neurodegenerative
disease processes, such as Alzheimer's disease, Parkinson's disease, and
Creutzfeldt-Jakob disease. Ultimately, such NMR studies may again lead
to the development of tests and treatments for diseases in man.

24. The future of NMR
• NMRisclearlyapowerfultoolinbiologicalresearch,butresearchersarestill
strivingforgreatersensitivityandresolutiontobroadenthescopeofpotential
applications.Consequently,newNMRtechniquesareconstantlybeing
developed.
• Thelatestadvances(inadditiontoincreasedmagneticfieldstrength)include
refrigeratedmagnettechnologythatallowscontinuousNMRoperation
withouttheneedforcryogenrefilling,givinggreaterexperimentflexibilityand
small-anglex-rayscattering(SAXS)NMRthatprovidesmorestructuraldetail
thanNMRaloneandcanbeperformedusingsmallersamples.