3. OBJECTIVES
• Introduction
• Working Principle
• Instrumentation
• Chemical shift
• Spin-spin coupling
• NMR Spectra interpretation
• Application
• Cons and Prons
• Conclusion
4. Introduction
• NMR is an analytical technique used to study the structure and
properties of molecules .
• When a sample is subjected to a strong magnetic field and radio
frequency radiation, NMR provides a valuable information about the
structure, dynamics & interactions of molecules
5. Working principle……..
• NMR relies on the fact that atomic nuclei with an odd number of
protons or neutrons have an inherent angular momentum or spin.
• When placed in a magnetic field, these nuclei align with or against
the field.
• Applying radiofrequency pulses to the sample causes nuclei to
transition between spin states, absorbing energy.
• Upon relaxation, the nuclei release this energy, producing a
detectable signal that can be analyzed to glean information about the
sample's environment.
6. Working principle
• NMR spectroscopy works by exploiting the magnetic properties of
atomic nuclei
• When placed in a strong magnetic field and exposed to
radiofrequency pulses, certain nuclei absorb and emit energy.
• By analysing these signals, NMR can provide information about a
molecular structure, chemical environment and interaction of
compounds.
• The resonant frequency at which nuclei absorb energy is influenced
by their local environment, allowing researchers to deduce structural
and molecular information.
9. Chemical shift
• This is the displacement of resonances from a reference compound.
• It's influenced by the local electron density around the nucleus
• this reveals information about chemical environments.
• It also describes the shift in resonant frequency of an atomic
nucleus(typically hydrogen) in a molecule due to the influence of the
surrounding electrons and magnetic field
• The shift is measured in ppm relative to a reference standard such as
tetramethylsilane (TMS)
• The chemical shift is used to identify different chemical environments
in a molecule and to study the structure, dynamics and interactions of
molecules
10. Spin-spin coupling
• Spin-spin coupling arises when two or more nuclei interact through
their magnetic fields.
• This coupling reveals the number of neighboring nuclei and their
relative positions.
• The splitting patterns in the NMR spectrum offer insights into
molecular connectivity
11. NMR Spectra interpretation
• NMR spectra show peaks corresponding to different nuclei in the
sample.
• The chemical shifts, splitting patterns, and peak integrations provide
information about the types of nuclei, their environment, and
structural arrangements in the molecule.
12. Application
• chemistry: to determine the molecular structures, studying chemical
reactions and analyzing compound’s purity
• biochemistry: to study biomolecular structures, protein folding
interactions and dynamics
• medicine: aids in medical imaging like MRI
• food science: helps in analyizing food components, studying
molecular changes during pressing
• forencics: used to identify chemical compounds in crime scene
investigations and analyzing evidence
13. CONS AND PRONS
PRONS
• Non-destructive analysis
(samples are not damaged)
• High structural information.
• Quantitative analysis.
• Versatility across compounds
• helps in identifying function
groups present in compounds,
aiding in compound
characterization
CONS
• Requires relatively large sample
quantities.
• Low sensitivity
• Expensive equipment.
• May not be suitable for all types of
molecules.
• Complex interpretation for
complex spectra.
14. CONCLUSION
• NMR spectroscopy is a technique that enables researchers to probe
the inner workings of molecules, revealing vital information about
their structure, dynamics, and interactions. While it has its challenges,
the wealth of insights it provides makes it a vital tool in the displine of
science.
