1D-2D NMR- dhanashree kolhekar- BBAU, Lucknow.pptx

BABASAHEB BHIMRAO AMBEDKAR UNIVERSITY
[बाबासाहेब भीमराव अम्बेडकर विश्वविद्यालय]
Vidya Vihar Raebareli Road, Lucknow, Uttar Pradesh 226025.
Contact No.- 0522-24400096, 0522-2968833
(A CENTRAL GOVT. UNIVERSITY)
ACCREDITED ‘A++' GRADE BY NAAC 2023
NIRF RANT- 33 (2024)
ISO 14001:2015
Presented By :-
Dhanashree G. Kolhekar
Semester: 2nd
M.Pharm. [Pharm. Analysis]
Supervisor :-
Dr. CHIMPIRI SRUJANI
Assistant Professor
Pharm. Analysis
BBAU, Lucknow
PRESENTATION
In partial fulfillment of the requirement for the degree of Master of Pharmacy (Pharmaceutical Analysis)
ON TOPIC ENTITLED
1D 2D NMR
Department of Pharmaceutical Sciences
School of Pharmaceutical Sciences
Babasaheb Bhimrao Ambedkar
University

TABLE OF CONTENT-
HISTORY OF NUCLEAR MAGNETIC RESONANCE.
INTRODUCTION TO NUCLEAR MAGNETIC RESONANCE.
FUNDAMENTAL PRINCIPLE.
INSTRUMENTATION COMPONENTS.
1D NMR.
2D NMR.
COMPARISON BETWEEN DIFFERENT TYPES OF 1D & 2D NMR
SIMILARITIES BETWEEN 1D & 2D NMR.
CONCLUSION.
REFRENCES.

Historical Background
•1938: Isidor Rabi first observed nuclear magnetic resonance in
molecular beams of lithium chloride, extending the Stern–Gerlach
experiment (Nobel Prize 1944).
•1946: Felix Bloch and Edward M. Purcell independently
demonstrated NMR in bulk matter (liquids and solids), earning the
Nobel Prize in Physics in 1952.
•1960s–1970s: Development of Fourier transform NMR by
Richard Ernst dramatically improved sensitivity and resolution,
laying groundwork for multidimensional techniques (Nobel Prize
1991).

Introduction to NMR
•Definition: Nuclear Magnetic Resonance (NMR) is a spectroscopic technique that
exploits the magnetic properties of certain nuclei to elucidate molecular structure,
dynamics, and interactions.
•Historical Context: Developed in the mid-20th century, NMR has evolved into a
powerful tool in organic chemistry, biochemistry, and pharmaceutical sciences.
•Importance:
• Non-destructive analysis
• Provides detailed information on chemical environments (chemical shifts,
coupling constants)
• Used for purity analysis, structure confirmation, and quantitative studies.

Fundamental Principle
•Nuclear Spin and Magnetic Moment: Nuclei with an odd mass or atomic number
possess spin (I ≠ 0) and an associated magnetic moment. Under a static magnetic
field (B ), these spins align parallel (lower energy) or antiparallel (higher energy).
₀
•Resonance Condition: Transitions between spin states occur when radiofrequency
energy (ℏω) matches the Larmor frequency, ω = γB , where
₀ γ is the gyromagnetic
ratio.
•Chemical Shift (δ): Electronic environments shield nuclei to varying extents; the
resulting small shifts in resonance frequency relative to a standard (e.g., TMS) report
on functional groups and bonding.
•Spin–Spin Coupling (J-coupling): Through-bond interactions split peaks into
multiplets (doublets, triplets, etc.), revealing connectivity and dihedral angles.
•Relaxation: Longitudinal (T ) and transverse (T ) relaxation describe return to
₁ ₂
equilibrium and coherence decay, influencing sensitivity and experimental timing.

INSTRUMENTATION COMPONENTS –
An NMR spectrometer comprises three main assemblies :
1.Superconducting Magnet: Generates a stable, homogeneous B field
₀
(commonly 400–1000 MHz for ^1H) using cryogenically cooled coils.
2.RF Probe and Transmitter/Receiver: The probe houses coils for
transmitting pulses and detecting emitted signals. Tuned circuits match
impedance and optimize sensitivity.
3.Console and Workstation Computer: Controls pulse sequences, gradient
coils (for imaging or multidimensional NMR), and data acquisition; processes
free induction decays via Fourier transformation.
Additional hardware includes field-lock (deuterium channel) to maintain B₀
stability, shim coils for homogeneity, and gradient amplifiers for spatial
encoding and multidimensional experiments.

TYPES OF NUCLEAR MAGNETIC RESONANCE EXPERIMENTS-
•One-Dimensional (1D): ^1H NMR, ^13C NMR, ^31P NMR for basic structural analysis.
•Two-Dimensional (2D): COSY, HSQC, HMBC reveal through-bond and through-space
correlations, elucidating complex architectures.
•Multidimensional: 3D/4D NMR applied to large biomolecules (proteins, nucleic acids) for
resonance assignment and dynamics.
•Solid-State NMR: Magic-angle spinning (MAS) and cross-polarization techniques characterize
insoluble or crystalline materials.
•Magnetic Resonance Imaging (MRI): Spatially resolved NMR for clinical and preclinical
imaging.

APPLICATIONS OF NMR–
•Structural Elucidation: Identify and confirm the structure of organic compounds.
•Purity Analysis: Detect impurities or unexpected by-products.
•Dynamics and Kinetics: Study molecular motions and reaction kinetics.
•Biomolecular Studies: Investigate proteins, peptides, and nucleic acids (often using 2D and higher-
dimensional techniques).
•Pharmaceutical Research: Validate the chemical identity and purity of drug substances and
formulations.
•Environmental monitoring and analysis (soil, water, and air pollutants, water quality, etc.)
•Geochemistry – age determination, soil, and rock composition, oil and gas surveying
•Chemical and Petrochemical industry – Quality control
•Identify structures of biomolecules, such as carbohydrates, nucleic acids
•Sequence biopolymers such as proteins and oligosaccharides
•Determination of the molecular mass of peptides, proteins, and oligonucleotides.
•Monitoring gases in patients’ breath during surgery.
•Identification of drug abuse and metabolites of drugs of abuse in blood, urine, and saliva.
•Analyses of aerosol particles.
•Determination of pesticides residues in food.

1D and 2D NMR
Techniques
NMR EXPERIMENTS CAN BE PERFORMED IN ONE DIMENSION (ID) OR TWO DIMENSION (2D)
DEPENDING UPON THE COMPLEXITY OF THE SYSTEM BEING STUDIED.

🧪 1D NMR (One-Dimensional Nuclear Magnetic Resonance)
1D NMR is the simplest form of NMR spectroscopy, where the resonance of nuclei
(commonly ^1H or ^13C) in a magnetic field is measured and presented as a one-
dimensional spectrum. This technique provides basic information about the chemical
environment of nuclei in a molecule, such as chemical shifts, integration (number of
nuclei), and splitting patterns due to spin-spin coupling. It is quick and easy to perform,
making it essential for routine analysis.
🔬 2D NMR (Two-Dimensional Nuclear Magnetic Resonance)
2D NMR is an advanced spectroscopic technique that extends the capabilities of 1D
NMR by incorporating a second frequency dimension. This allows for a more
comprehensive analysis of molecular structures, particularly useful for complex
molecules where 1D spectra may have overlapping signals. 2D NMR experiments, such
as COSY, HSQC, and NOESY, provide information on the connectivity between atoms,
both through bonds and through space, enhancing the understanding of molecular
architecture.

Definition
 ID NMR spectroscopy is simple technique in which pulse 90 degree is provided to sample which
is placed in uniform magnetic field. As a result a FID signal (raw form) is obtained. To get
meaningful data, Fourier Transform program on FID is applied to get desired signal. Data in form
of frequency vs intensity is plotted long x-axis and y-axis respectively.
 In ID NMR, the spectrum is typically displayed as a graph with the chemical shift on the x-axis
and the intensity on the y-axis. The chemical shift represents the resonance frequency of the
nuclei and is measured in parts per million (ppm) relative to a standard compound. The intensity
of the peaks in the spectrum reflects the number of nuclei in the sample that resonate at a
particular frequency.
 It is a type of spectroscopy where the energy states of spin-active nucleus placed in a static
magnetic field are interrogated by inducing transitions between the states via radiofrequency
irradiation.
 Contain sequence of radio frequency pulses.
 Plot-Chemical shift vs radiofrequency.
 Includes regular H-proton spectrum, C-13 spectra.
1D NMR Technique -

Principle-
Consist of 2 sections
 #Preparation
 #Detection
PREPARATION-
A 90°pulse is applied which rotates the equilibrium magnetization
along Z axis to Y axis
 This induces a signal in receiver coil.
 The signal decays due to t2 relaxation & is called as free
induction decay(fid)
 FOURIER TRANSFORMATION to get final ID spectrum.
TYPES-
1. REGULAR
 Sample reaches equilibrium.
 RF signal is transmitted.
 Signal is evolved(FID)
 Fourier transformation
 Final spectra is obtained

2) DECOUPLED
Heteronuclear coupling from another nucleus with magnetic
spin causes the signal to split & sensitivity to fall.
Apply decoupling is necessary.
GATED DECOUPLING
➤ Apply decoupling during relaxation time.
OTHER METHODS OF DECOUPLING-
-Off resonance
-Solvent suppression
-Deuterium substitution
NUCLEAR OVERHAUSER EFFECT
The local field of one nucleus is affected by another nucleus.
Causes reduction in intensity of signal.

1D NMR SPECTRAL ANALYSIS
Contain following information for analysis,
#Chemical shift
#Spin-Spin coupling
#Intensity
INTERPRETATION OF H-NMR
No: of signals-Indicates how many different kinds of protons are present.
Position of signals: Chemical shift.
Intensity of signals: No: of protons.
Splitting of signals: No: of nearby nuclei usually protons.
1. Proton NMR (1H NMR)
This is the most commonly used ID NMR technique, provides information about the hydrogen (proton)
environments in a molecule.
2. Carbon-13 NMR (13C NMR)
Unlike 1H NMR, this technique provides information about carbon environments in a molecule. It is less
sensitive than 1H NMR due to the lower natural abundance of the 13C isotope, but it is valuable for
studying the carbon skeleton, functional groups, and isotopic labeling in organic compounds.
3. Other Nuclei
NMR can also be performed on other nuclei such as nitrogen-15 (15N NMR), phosphorus-31 (31P NMR),
and fluorine-19 (19F NMR).

2D NMR Technique –
Definition -
 Unlike traditional one-dimensional NMR, which provides information about chemical shifts and coupling
constants, 2D NMR allows the correlation of two different types of interactions within a molecule.
 In 2D NMR, two independent radiofrequency pulses are applied to the sample, resulting in a series of data
points that form a matrix or spectrum. Each data point corresponds to a specific combination of
resonances from the molecule, providing information about their correlations.

Two-Dimensional NMR (2D-NMR)
Basis: interaction of nuclear spins (1H with 'H, 1H with 13C, etc.) plotted in two dimensions
Applications:
Simplifies analysis of more complex or ambiguous cases such as proteins
Obtain structural information not accessible by one-dimensional NMR methods
Techniques include:
1) Correlation Spectroscopy (COSY)
2) Heteronuclear Correlation Spectroscopy (HETCOR)
3) Heteronuclear Multiple-Quantum Coherence (HMQC)
4) Nuclear Overhauser Effect Spectroscopy (NOESY)
5) Incredible Natural Abundance Double Quantum Transfer Experiment (INADEQUATE)
6) Total Correlation Spectroscopy (TOCSY), Many others

Correlation Spectroscopy (COSY)
It is a fundamental two-dimensional (2D) NMR technique used to identify through-bond interactions
between hydrogen atoms (protons) in a molecule. It helps determine which protons are coupled (J-coupled)
to each other, which is essential in determining the structure and connectivity of molecules, especially
organic compounds.
📌 Applications of COSY:
1.Structure Elucidation: Identifies which hydrogens are neighbors, helping to map out a molecule's
backbone.
2.Assignment of Overlapping Peaks: Distinguishes overlapping signals in 1D NMR.
3.Conformational Analysis: Helps determine the spatial arrangement of atoms in flexible molecules.
4.Useful in Natural Products and Complex Organic Molecules.
📚 Example:
In ethanol (CH CH OH):
₃ ₂
•The methyl group (CH ) couples with the methylene (CH ), giving cross-peaks.
₃ ₂
•CH couples with the OH proton in hydrogen-bonding conditions, which may also be observed in COSY.
₂
✅ Conclusion:
COSY NMR is a powerful 2D technique for establishing connectivities between protons via scalar
couplings. It enhances the structural information obtainable from 1D spectra and is especially useful for
analyzing complex or overlapping spectra.

Heteronuclear Correlation Spectroscopy (HETCOR)
It is a 2D NMR technique used to identify interactions between different types of nuclei—commonly ^1H
(proton) and ^13C (carbon)—that are directly bonded to each other. It is a powerful tool for structural
elucidation, especially when combined with other techniques like COSY.
📈 HETCOR Spectrum Interpretation:
•The horizontal axis (X-axis) typically represents ^1H chemical shifts.
•The vertical axis (Y-axis) represents ^13C or other heteronuclear chemical shifts.
•Cross-peaks indicate a proton-carbon (or proton-nitrogen, etc.) pair that is directly bonded.
📌 Applications of HETCOR:
1.Structure Elucidation: Assigns carbon or other heteronuclear signals by linking them to known proton
signals.
2.Clarifies Overlapping Signals: Especially useful when ^13C NMR signals are ambiguous or congested.
3.Complex Molecule Analysis: Widely used in organic, pharmaceutical, and natural product chemistry.
📚 Example:
In ethanol (CH CH OH):
₃ ₂
•HETCOR can show cross-peaks between the methyl protons and the ^13C of the methyl group.
•Similarly, the methylene protons will correlate with the methylene carbon.
✅ Conclusion:
HETCOR NMR is an essential tool for correlating protons to heteronuclei in a molecule, particularly for
assigning carbon spectra and understanding bonding relationships. It significantly improves the clarity of
structural analysis by enabling direct proton-to-carbon (or other nucleus) assignments in complex
compounds.

Heteronuclear Multiple-Quantum Coherence (HMQC)
It is a 2D NMR technique used to correlate protons (^1H) with directly bonded heteronuclei (commonly ^13C or
^15N) via scalar coupling. It is similar to HETCOR but generally more sensitive and faster, making it useful for
high-resolution structural analysis.
🧪 Principle:
HMQC relies on the transfer of magnetization through scalar (J) coupling between a proton and a heteronucleus. It
uses multiple-quantum coherence states, which involve the simultaneous flipping of both nuclei, to correlate the two
types of atoms.
•The coherence refers to the combined behavior of the proton and its attached carbon or nitrogen during the pulse
sequence.
•The resulting 2D spectrum shows cross-peaks at positions corresponding to pairs of directly bonded nuclei.
📌 Applications of HMQC:
1.Rapid Structure Assignment: Helps quickly assign carbon or nitrogen atoms based on known proton shifts.
2.High Sensitivity: Ideal for samples with low concentration or naturally low abundance nuclei (^13C, ^15N).
3.Pharmaceutical Analysis: Widely used in small molecule and drug development for detailed structure
confirmation.
📚 Example:
In an alkyl chain, the methylene protons (–CH2–) will show cross-peaks with their directly attached carbon, allowing
easy identification of chain segments.
✅ Conclusion:
HMQC NMR is a powerful 2D technique for directly correlating protons to their bonded heteronuclei, offering
greater sensitivity and speed than traditional methods like HETCOR. It is highly valuable in organic synthesis,
natural product chemistry, and drug development for accurate structural assignments.

NOESY (Nuclear Overhauser Effect Spectroscopy) -
It is a 2D NMR technique used to determine spatial proximity between non-bonded protons in a molecule. Unlike
COSY or HETCOR, which show through-bond interactions, NOESY reveals through-space interactions—important
for determining 3D molecular structures.
🧪 Principle:
NOESY is based on the nuclear Overhauser effect, a phenomenon where relaxation of one nucleus affects another
nearby nucleus, altering signal intensity. This occurs due to dipole-dipole interactions between spatially close
protons.
•NOE is distance-dependent, making NOESY ideal for understanding molecular conformation and folding.
•Useful in analyzing both small organic compounds and large biomolecules like proteins and nucleic acids.
📌 Applications of NOESY:
1.3D Structure Determination – Especially in proteins, peptides, and nucleic acids.
2.Conformational Analysis – Reveals folding, ring flips, and stereochemistry.
3.Stereochemistry & Configuration – Helps in distinguishing isomers based on spatial arrangement.
4.Drug Discovery – Understands ligand–receptor binding via proximity relationships.
📚 Example:
In a cyclic compound or protein: NOESY can show that two hydrogen atoms far apart in the sequence are close in
space due to folding.
✅ Conclusion:
NOESY NMR is an essential 2D technique for analyzing spatial relationships between protons. It complements
other NMR methods by revealing how atoms are positioned in three-dimensional space, aiding in conformational
and stereochemical analysis of molecules.

INADEQUATE
It is a 2D NMR spectroscopy technique used to identify directly bonded carbon–carbon (^13C–^13C)
pairs. Although challenging due to the low natural abundance of ^13C (only ~1.1%), INADEQUATE
provides definitive information about carbon skeleton connectivity, making it invaluable for structure
elucidation in complex organic molecules.
🧪 PRINCIPLE:
•INADEQUATE works on the principle of double quantum coherence.
•It detects scalar coupling (^1J_CC) between two directly bonded ^13C atoms.
•Since natural ^13C abundance is low, the probability of two adjacent ^13C atoms is rare (≈0.01%), making
the experiment sensitive and data acquisition-intensive.
•Despite this, INADEQUATE gives unambiguous carbon–carbon connectivity, which is especially useful
when ^1H NMR or ^1H–^13C correlations are not enough.
📌 Applications of INADEQUATE:
1.Carbon Skeleton Elucidation – Useful in natural products, alkaloids, steroids, and complex organics.
2.Confirmation of Molecular Frameworks – When ^1H NMR and HSQC/HMBC are insufficient.
3.Structural Revisions – Can correct misassigned structures based on proton-only data.
4.Labeling Studies – Powerful when using ^13C-enriched compounds for metabolic or synthetic analysis.
📚 EXAMPLE:
In a substituted aromatic compound, INADEQUATE can show which carbon atoms are directly bonded,
helping identify substitution patterns or ring structures.

⚙️Pulse Sequence & Instrumentation:
•Requires high-field NMR spectrometer with excellent sensitivity and stability.
•The pulse sequence:
• Excites double quantum coherence (involving both coupled ^13C nuclei).
• Allows evolution and transfer of magnetization.
• Detects single quantum coherence to generate a 2D map.
📈 INADEQUATE Spectrum Interpretation:
•X-axis & Y-axis: Both represent ^13C chemical shifts.
•Diagonal line: Represents ^13C single quantum signals.
•Cross-peaks (off-diagonal): Indicate direct ^13C–^13C bonds.
Each cross-peak connects two bonded ^13C atoms, providing a carbon–carbon connectivity map of
the molecule.
✅ CONCLUSION:
INADEQUATE NMR is a gold-standard method for determining direct carbon–carbon
connectivity in a molecule, providing unambiguous structural insights. Despite its challenges—
such as low sensitivity and long acquisition times—it is exceptionally valuable for resolving complex
molecular architectures, especially in research and drug development involving natural products or
novel chemical entities.

🧪 Total Correlation Spectroscopy (TOCSY)
TOCSY (Total Correlation Spectroscopy) is a 2D NMR technique that extends the concept of through-bond spin-
spin coupling seen in COSY, allowing you to observe correlations between all protons within the same spin
system, not just directly coupled ones. It’s especially useful for complex organic molecules and biomolecules like
peptides, carbohydrates, and nucleotides.
🧪 Principle:
TOCSY uses isotropic mixing (a spin-locking technique) that allows magnetization transfer through a network
of coupled protons. Unlike COSY, which only shows direct coupling, TOCSY reveals extended coupling chains
—helpful when analyzing molecules with repeating units or overlapping signals.
•The key mechanism is J-coupling (scalar coupling).
•Magnetization is transferred throughout the spin system via a mixing pulse (usually MLEV or DIPSI sequences).
📈 TOCSY SPECTRUM INTERPRETATION:
X-axis and Y-axis:
Both show proton (^1H) chemical shifts.Diagonal peaks: Proton signals (like 1D NMR).Cross-peaks: Show
correlations between all protons in the same spin system, including indirect ones.
For example, in a sugar ring or amino acid residue, all the protons of the unit will correlate with each other through
TOCSY.
📚 EXAMPLE:
In glucose:
•TOCSY allows correlation from H-1 to H-6 within the glucose ring, even though some of these protons are not
directly coupled.

⚙️PULSE SEQUENCE & INSTRUMENTATION:
•Requires a high-resolution NMR instrument.
•Pulse sequence involves:
• Excitation of proton spins.
• Application of a spin-lock mixing period (e.g., 40–80 ms), allowing magnetization to spread
across all coupled nuclei.
• Detection of the resulting signals to generate a 2D spectrum.
📌 Applications of TOCSY:
1.Amino Acid and Sugar Analysis – Identifies spin systems of individual residues.
2.Peptide/Protein Assignment – Helps in sequential assignment of residues.
3.Metabolomics & Natural Products – Decodes complex, overlapping proton environments.
4.Mixture Analysis – Differentiates multiple spin systems even within mixtures.
✅ CONCLUSION:
TOCSY NMR is a powerful tool for identifying entire spin systems within a molecule by
transferring magnetization across multiple bonded protons. It is especially important for resolving
complex, overlapping NMR signals and is widely used in structural biology, natural product
chemistry, and metabolomics.

COMPARISON BETWEEN DIFFERENT TYPES OF 1D & 2D NMR
ASPECTS 1D NMR 2D NMR
Principle Measures resonance frequencies Measures correlations between spins
Resolution Lower resolution Higher resolution
Information Chemical shifts and peak integrals Chemical shifts, coupling constants, and
spin-spin correlations
Spectrum Provides a spectrum with one
dimension (frequency or time)
Provides a spectrum with two
dimensions (frequency-frequency or
time-frequency)
Peaks
Each peak corresponds to a
specific nuclear environment
Peaks are cross-peaks that represent
interactions between nuclei
Sensitivity Lower sensitivity Higher sensitivity

Signal Interpretation
Provides information about the molecular
framework
Provides detailed structural information,
such as connectivity, and spatial
proximity of atoms
Complexity of Experiment Simpler experiment setup and data
interpretation
More complex experiment setup and
data interpretation
Applications
Routine analysis of small organic molecules,
identification of functional groups,
quantification of compounds, purity
assessment
Structure determination of complex
organic compounds, analysis of mixtures,
protein structure analysis, drug discovery.
EXAMPLES
Proton (1H) NMR, Carbon (13C) NMR, DEPT,
APT, etc.
COSY, TOCSY, NOESY, HSQC, HMBC,
ROESY, INADEQUATE, HMQC, etc.
GRAPHICAL PRESENTATION OF
PULSE SEQUENCES-

SIMILARITIES BETWEEN 1D & 2D NMR.
Nuclear Spins Both techniques utilize nuclear spins
Spectral Data Both provide spectral data of the sample
Detects Chemical Shifts
Both techniques utilize the concept of chemical shifts, which result from
the influence of local electron density on the magnetic environment of a
nucleus. Chemical shifts are observed in both ID and 2D NMR spectra and
can be used to identify functional groups, differentiate between different
molecular species, and probe molecular conformation
Spin-Spin Couplings
Both 1D and 2D NMR can detect and characterize spin-spin coupling
between nuclei in a molecule. Spin-spin coupling manifests as splitting of
NMR signals and provides information about the connectivity and spatial
relationships between atoms in a molecule.
Signal Intensities
In both ID and 2D NMR, the intensities of NMR signals are proportional
to the number of nuclei contributing to each signal. The relative peak
heights in the spectra provide information about the relative abundance
or concentration of specific molecular species.

Molecular Structure Both can be used to analyze the molecular structure
Relaxation Times Both techniques can measure relaxation times
Information on
Connectivity Both can provide information on the connectivity of atoms
Utilizes Fourier
Transform
Both ID and 2D NMR techniques rely on Fourier transformation to convert
time-domain NMR signals into frequency-domain spectra. The
transformation allows the separation and analysis of individual NMR
signals, enabling the extraction of valuable information about the
molecular system.
Principle
Both techniques are based on the principle of clear magnetic resonance,
where the behavior of atomic nuclei atomic nuclei in a magnetic field is
analyzed.
Nuclei Both techniques can be used to study various atomic nuclei, including
hydrogen (1H), Carbon (13C), Nitrogen (15N), others.

Spectral Information
Both technique provide spectral information, including chemical shifts, which
reflect the local chemical environment of the nuclei, and coupling constants,
which reveal the interactions between neighboring nuclei.
Analysis of
Both techniques are widely used in the analysis of organic compounds, helping to
determine their molecular structures, identify functional groups, and study their
conformations.
Sensitivity
Both techniques can provide quantitative information about the relative
abundance of different nuclei within a sample.
Applications Both techniques find applications in various fields, including chemistry,
biochemistry, pharmaceuticals, materials science, and environmental analysis.
Instrumentation
Both techniques require specialized NMR instruments, typically equipped with
magnets, radiofrequency (RF) coils, detectors, and data acquisition systems.

CONCLUSION –
• NMR spectroscopy is based on the principle that certain atomic nuclei possess a property called spin,
which gives rise to a magnetic moment. NMR spectroscopy is widely used in various fields, including
chemistry, biochemistry, and medicine, to determine the arrangement of atoms in a molecule, analyse
chemical reactions, and investigate molecular interactions. It provides detailed information about the
connectivity, stereochemistry, and conformation of molecules.
🧪 1D NMR (One-Dimensional NMR)
1D NMR is the foundational technique in NMR spectroscopy, providing essential information about the
chemical environment of nuclei within a molecule. It is particularly effective for small to moderately
complex molecules, offering insights into:
•Chemical Shifts: Indicating the electronic environment surrounding nuclei.
•Integration: Revealing the relative number of nuclei contributing to a signal.
•Spin-Spin Coupling: Providing information on the connectivity between atoms through splitting
patterns.
Due to its simplicity and speed, 1D NMR is widely used for routine structural elucidation and purity
assessment.

🔬 2D NMR (Two-Dimensional NMR)
2D NMR extends the capabilities of 1D NMR by correlating interactions between different nuclei,
making it invaluable for analyzing complex molecules, such as proteins and nucleic acids. It provides
detailed information on:
•Through-Bond Correlations: Identifying which atoms are connected via chemical bonds (e.g.,
COSY, HSQC).
•Through-Space Interactions: Determining spatial proximity between atoms (e.g., NOESY).
•Molecular Dynamics: Offering insights into the flexibility and conformational changes within
molecules.
By spreading spectral information across two dimensions, 2D NMR resolves overlapping signals and
facilitates comprehensive structural analysis.
While 1D NMR is ideal for quick and straightforward analysis of simpler molecules, 2D NMR is
essential for unraveling the complexities of larger, more intricate structures. Together, they form a
complementary suite of techniques that are fundamental to modern chemical and biochemical
research.

REFERENCES AND SOURCES –
 Spectrophotometric identification of organic compounds by Silverstein, Barsler and Morril.
Fifth edition;227-267.
 Instrumental methods of chemical analysis by Gurdeep.R.Chatwal and Sham.k.Anand.
Himalaya publishing house:4.73-5.63
 ID and 2D NMR experiment methods by Dr.Shaoxiong. Wu: April 14:2011
 https://www.thermofisher.com/au/en/home/life-science/protein-biology/protein-biology-
learning-center/protein-biology-resource-library/pierce-protein-methods/overview-mass-
spectrometry.html
 https://www.slideshare.net/akshukumarsharma/mass-spectroscopy 55382941
 http://www.chem.ucalgary.ca/courses/350/Carey5th/Ch13/ch13-ms.html
 https://en.wikipedia.org/wiki/Mass_spectrometry
 https://www.chemguide.co.uk/analysis/masspec/howitworks.html
 https://www.slideshare.net/solairajananant/mass-spectrometry-38534267
 https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/spectrpy/massspec/masspec1.htm

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