It is an analytical technique uselful for detection of functional groups present in particular molecules and compounds.
It is highly applicable in pharmaceutical and chemical engineering.
this ppt contain all basic information related to the mass spectrometry like introduction, principle of MS, type of ions, fragmentation processes eg. mcLafferty rearrangement, alpha clevage, sigma bond clevage, retro-diels-alder reaction
Fluorescence spectroscopy becomes a widely used tool at the interface of biology, chemistry and physics, because of its precise sensitivity and recent technical advancements. The measurements can provide information on a wide range of molecular processes including the interactions of solvent molecules with fluorophores, rotational diffraction of biomolecules, distance between sites of biomolecules, conformational changes and binding interactions. These advances in fluorescence technology are decreasing the cost and complexity of previously complex processes. Fluorescence spectroscopy is a highly developed and non-invasive technique that enables the on-line measurements of substrate and product concentrations or the identification of characteristic process states.
this ppt contain all basic information related to the mass spectrometry like introduction, principle of MS, type of ions, fragmentation processes eg. mcLafferty rearrangement, alpha clevage, sigma bond clevage, retro-diels-alder reaction
Fluorescence spectroscopy becomes a widely used tool at the interface of biology, chemistry and physics, because of its precise sensitivity and recent technical advancements. The measurements can provide information on a wide range of molecular processes including the interactions of solvent molecules with fluorophores, rotational diffraction of biomolecules, distance between sites of biomolecules, conformational changes and binding interactions. These advances in fluorescence technology are decreasing the cost and complexity of previously complex processes. Fluorescence spectroscopy is a highly developed and non-invasive technique that enables the on-line measurements of substrate and product concentrations or the identification of characteristic process states.
Introduction,Instrumentation, Classification of electronic transitions, Substituent and solvent effects, Classification of electronic transitions
Substituent and solvent effects
Applications of UV Spectroscopy
UV spectral study of alkenes
UV spectral study of poylenes
UV spectral study of α, β-unsaturated carbonyl
UV spectral study of Aromatic compounds
Empirical rules for calculating λmax.
Applications of UV Spectroscopy, Empirical rules for calculating λmax.
Nmr nuclear magnetic resonance spectroscopyJoel Cornelio
Basics of NMR. Suitable for UG and PG courses.
Includes principle, instrumentation, solvents. chemical shift and factors affecting it. Some problems. resolving agents, coupling constant and much more
Quadrupole and Time of Flight Mass analysers.Gagangowda58
Description about important mass analysers Quadrupole and TOF: Principle, Construction and Working, Advantages and Disadvantages and their Applications.
Introduction, Basic Principles, Terminology, Instrumentation, Ionization techniques (EI, CI, FAB, MALDI, and ESI), Mass Analyzer (Magnetic sector instruments, Quadrupole, TOF, and ICR ), and Applications of Mass Spectrometry.
Introduction,Instrumentation, Classification of electronic transitions, Substituent and solvent effects, Classification of electronic transitions
Substituent and solvent effects
Applications of UV Spectroscopy
UV spectral study of alkenes
UV spectral study of poylenes
UV spectral study of α, β-unsaturated carbonyl
UV spectral study of Aromatic compounds
Empirical rules for calculating λmax.
Applications of UV Spectroscopy, Empirical rules for calculating λmax.
Nmr nuclear magnetic resonance spectroscopyJoel Cornelio
Basics of NMR. Suitable for UG and PG courses.
Includes principle, instrumentation, solvents. chemical shift and factors affecting it. Some problems. resolving agents, coupling constant and much more
Quadrupole and Time of Flight Mass analysers.Gagangowda58
Description about important mass analysers Quadrupole and TOF: Principle, Construction and Working, Advantages and Disadvantages and their Applications.
Introduction, Basic Principles, Terminology, Instrumentation, Ionization techniques (EI, CI, FAB, MALDI, and ESI), Mass Analyzer (Magnetic sector instruments, Quadrupole, TOF, and ICR ), and Applications of Mass Spectrometry.
FTIR is a characterisation technique to evaluate the composition of the sample such as nanoparticles, nanospheres, chemical drugs and composites etc. It is time efficient as useful for bulk sample analysis.
The detailed information of UV Visible Spectroscopy, it includes the information regarding electronic transitions, Electromagnetic radiations, Various shifts.
UV - Visible Spectroscopy detailed information is included .The Spectroscopy study provide the information and the absorbance as well the concentration of the drugs is studied.
Country wise comparison of essential drugs on the basis of rational drug use ...AJAYKUMAR4872
The provision of Essential medicine is one of the eight pillars of WHO’s primary health care strategy. According to WHO, essential medicines are those drugs that fulfill the priority health care need of people. Essential drug is defined as the appropriate medicine intended to be available in the content of functioning health system every time in adequate amount in the appropriate dosage form with assured quality and adequate information at affordable price that each and every individual can afford.
Iron deficiency anemia is the most advanced stage of iron deficiency which is characterized not only by low hemoglobin and Hematocrit levels but also by a reduction or depletion of iron stores, by low serum iron levels and decreased transferrin saturation.
UV spectroscopy is an analytical method used to detct the numbers of double and triple bonds present in dienes ,trienes and polyenes compounds.The energy corresponds to EM radiation in the ultraviolet (UV) region, 100-350 nm, and visible (VIS) regions 350-700 nm of the spectrum is known as UV spectrum.
Quality is absolute and universally recognizable. It is often loosely related to a comparison of features and characteristics of products, as ANSI/ASQ defines as relative quality.For Example, high-priced German automobiles are often thought of as being of higher quality than the lower priced models of other manufacturers.A management approach for an organization, centered on quality, based on the participation of all its members and aiming at long-term success through customer satisfaction, and benefits to all members of the organization and to society which can be called as Total Quality Management(TQM).
Q.R are planned and documented by an inspections of a review item
The review item may be a product, a group of related products or a part of a product
If the error identified earlier the cost of implication is less and the penalty for failing to conduct adequate reviews.
Documentation control - principles of GMPAJAYKUMAR4872
Documentation is an essential part of QA and relates to all aspects of GMP.
The pharmaceutical industry must have a good document framework (infrastructure).
It is important for a manufacturer to get the documentation right in order to get the product right.
Analytical Method Validation is a process that is used to demonstrate the suitability of an analytical method for an intended purpose.Regulations and quality standards that have an impact on analytical laboratories require analytical methods to be validated.
ISO:9000 family means organization of a product or service assuring continued quality assurance to customer delight.ISO 9000 was created to produce an international set of process quality standards.It consists of Written procedures that were inspected to ensure consistency
Electromagnetic radiation consists of waves of the electromagnetic field, propagating through space, carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, light, ultraviolet, X-rays, and gamma rays. All of these waves form part of the electromagnetic spectrum.EMR is released when excited atoms or molecules return to ground state and this process is called emisssion.
EMR has both electric (E) and magnetic (H) components that propagate at right angles to each other.
It is the documented act of proving that any procedure, process, equipment, material, activity or system actually leads to the expected result.
It is the confirmation by examination and the provision of objective evidence that the particular requirements for a specific intended use are fulfilled.
It is an analytical technique useful for the determination of molecular mass, molecular formula and fragmentation pattern of particular molecule and compounds. It has greater application in pharmaceutical and medicinal fields.
It is spectroscopy technique to determine number of hydrogen atoms present in the molecules and atoms.It is useful method for separation of molecules and compounds from mixtures components highly recommended in pharmaceutical and chemical engineering fields.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
3. Advancing spectroscopic analysis for over 65 years
1944 First IR spectrometer, the Model 12
1954 First commercial IR microscope
1957 First low-cost IR instruments
1975 First micro-processor controlled instrument, the
Model 281
1984 First rotating mirror pair design FT-IR
1987 First low-cost FT-IR
1990 First all-Cassegrain-objectives FT-IR
microscope
4. 1991 First FT-IR company to gain ISO 9001 accreditation
1995 First validated FT-IR software, Spectrum for
Windows®
1998 First FT-IR with smart accessory recognition
2001 First rapid-scanning chemical imaging system
2003 First FT-IR platform for both micro- and macro-
scale analysis of pharmaceutical materials
2004 First on-site fully upgradeable microscopy system
Historical Development of
IR
5. 2005 First integration of software sample table and
remote sampling interfaces
2007 First FT-IR/FT-NIR spectrometer with automated
range switching
2008 First high-accuracy FT-IR developed for optical
filter measurements
2011 First laboratory performance, low maintenance
and transportable FT-IR for everyday analysis
Historical Development of
IR
6. Spectroscopy is the study of the interaction of matter with the
electromagnetic spectrum
1. Electromagnetic radiation displays the properties of both particles and
waves
2. The particle component is called a photon
3. The energy (E) component of a photon is proportional to the frequency.
Where h is Planck’s constant and n is the frequency in Hertz (cycles per
second)
E = hn
4. The term “photon” is implied to mean a small, massless particle that
contains a small wave-packet of EM radiation/light – we will use this
terminology in the course
Introduction
7. 5. Because the speed of light, c, is constant, the frequency, n, (number
of cycles of the wave per second) can complete in the same time, must
be inversely proportional to how long the oscillation is, or wavelength:
6. Amplitude, A, describes the wave height, or strength of the oscillation
7. Because the atomic particles in matter also exhibit wave and particle
properties (though opposite in how much) EM radiation can interact
with matter in two ways:
• Collision – particle-to-particle – energy is lost as heat and
movement
• Coupling – the wave property of the radiation matches the wave
property of the particle and “couple” to the next higher quantum
mechanical energy level
n =
c = 3 x 1010 cm/s
___
l
c
E = hn =
___
l
hc
Introduction
8. 8. The entire electromagnetic spectrum is used by chemists:
UV
X-rays IR
g-rays Radio
Microwave
Energy (kcal/mol)
300-30 300-30 ~10-4
> 300 ~10-6
Visible
Frequency, n in Hz
~1015 ~1013 ~1010 ~105
~1017
~1019
Wavelength, l
10 nm 1000 nm 0.01 cm 100 m
~0.01 nm
~.0001 nm
nuclear
excitation
(PET)
core
electron
excitation
(X-ray
cryst.)
electronic
excitation
(p to p*)
molecular
vibration
molecular
rotation
Nuclear Magnetic
Resonance NMR
(MRI)
Introduction
9. C. The IR Spectroscopic Process
1. The quantum mechanical energy levels observed in IR
spectroscopy are those of molecular vibration
2. We perceive this vibration as heat
3. When we say a covalent bond between two atoms is of a
certain length, we are citing an average because the bond
behaves as if it were a vibrating spring connecting the two atoms
4. For a simple diatomic molecule, this model is easy to visualize:
Introduction
10. C. The IR Spectroscopic Process
5. There are two types of bond vibration:
• Stretch – Vibration or oscillation along the line of the bond
• Bend – Vibration or oscillation not along the line of the bond
H
H
C
H
H
C
scissor
asymmetric
H
H
C
C
H
H
C
C
H
H
C
C
H
H
C
C
symmetric
rock twist wag
in plane out of plane
Introduction
11. C. The IR Spectroscopic Process
6. As a covalent bond oscillates – due to the oscillation of the dipole
of the molecule – a varying electromagnetic field is produced
7. The greater the dipole moment change through the vibration, the
more intense the EM field that is generated
Introduction
12. C. The IR Spectroscopic Process
8. When a wave of infrared light encounters this oscillating EM field
generated by the oscillating dipole of the same frequency, the two
waves couple, and IR light is absorbed
9. The coupled wave now vibrates with twice the amplitude
IR beam from spectrometer
EM oscillating wave
from bond vibration
“coupled” wave
Introduction
14. Infrared spectroscopy is an instrumental
method of analysis that can be used to
identify and quantify samples ranging from
pharmaceuticals to diesel emissions.
wavelength is measured in "wavenumbers”
wavenumber = 1 / wavelength in
centimeters.
if wavelength is 2.5 µ= 1 / (2.5x10-4 cm)= 4000
cm-1
wavelength 15 µ corresponds to 667 cm-1
1 µ= 10-4 cm
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15. Mid IR most useful (chemical fingerprinting)
These absorptions represent vibrational and
rotational transitions
Change in dipole moment required during
vibration for IR absorption to occur
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Regions of wavelength range
IR wavelength Wave number
Near IR 0.8-2.5 µ 12,500-4000
cm–1
Mid IR 2.5-15 µ 4000-667 cm–1
Far IR 15-200 µ 667-50 cm–1
18. Modern IR is Fourier Transform instruments.
A Michelson interferometer produce interference
between two beams of light and was invented by
Albert Abraham Michelson.
It produces interference fringes by splitting a
beam of monochromatic light, one beam hits a
fixed mirror and the other hits a movable mirror.
When the reflected beams are combined, an
interference pattern is formed.
In all transmission experiments radiation from a
source is directed through the sample to a
detector.
The measurement of the type and amount of light
transmitted by the sample gives information about
the structure of the molecules comprising the
sample.
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20. In the IR region of the electromagnetic
spectrum, the absorption of radiation by a
sample is due to changes in the
vibrational energy states of a molecule.
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22. Linear molecules: 3N – 5 modes
Nonlinear molecules: 3N – 6 modes
Polyatomic molecules may exhibit coupling
which will alter predicted frequencies:
stretching-stretching
bending-bending
stretching-bending
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22
Note: strong coupling requires
interaction with a common atom
24. Frequency of molecular vibration, n (s–1)
depends on mass of atoms and strength of
bond:
The force constant, k, is about 500 N/m for a
typical single bond
The reduced mass, m (kg), is defined
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24
m
p
n
k
2
1
2
1
2
1
m
m
m
m
m
The pattern of absorption as a function of wavelength is called an IR
spectrum.
25. IR radiation does not have enough energy to
induce electronic transitions as seen with UV.
Absorption of IR is restricted to compounds
with small energy differences in the possible
vibrational and rotational states.
For a molecule to absorb IR, the vibrations or
rotations within a molecule must cause a net
change in the dipole moment of the molecule.
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26. Rotational transitions are of little use to the
spectroscopist.
Rotational levels are quantized, and
absorption of IR by gases yields line spectra.
However, in liquids or solids, these lines
broaden into a continuum due to molecular
collisions and other interactions.
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26
29. A percentage transmittance of 100 would mean
that all of that frequency passed straight through
the compound without any being absorbed.
In practice, that never happens - there is always
some small loss, giving a transmittance of
perhaps 95% as the best you can achieve.
A transmittance of only 5% would mean that
nearly all of that particular frequency is absorbed
by the compound. A very high absorption of this
sort tells you important things about the bonds in
the compound.
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29
41. To obtain an IR spectrum, the sample must
be placed in a “container” or cell that is
transparent in the IR region of the spectrum.
Sodium chloride or salt plates are a
common means of placing the sample in the
light beam of the instrument.
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42. Gases
• 10 cm to 120 cm path lengths (may utilize
multiple reflection)
Liquids—thin (0.1 mm) layers used
• Water or ROH are no-no’s (Why?)
• 10% in CCl4 (4000-1333 cm–1)
• 10% in CS2 (1333-650 cm –1)
• CHCl3, CH3CN, acetone for more polar
substances
• neat liquids
Evaporated Films
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44. Mulls (pastes)
Finely ground solid and mulling agent
fashioned into a thin film
oil, Nujol™, Fluorolubes used as mulling
agents
Pellets
Finely ground solid (1-100 mg) + KBr
Pressed into a transparent disk at 60,000 to
100,000 psi
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54. Light Path
(shown by red line)
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The light beam traverses the sample
compartment, as illustrated by the red line.
55. The sample is then scanned by the
instrument utilizing predesignated
parameters.
A relevant background scan should
already have been taken.
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57. A satisfactory spectrum has well
defined peaks-but not so intense
as to cause flattening on the
bottom of the peaks.
Major peaks can be labeled using
the peak function of the software
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58. Well-defined
peaks are
labeled with the
Wavenumbers
of the
Absorption
Maxima.
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58
The spectrum can then be printed using the print
function of the software.
59. Sample of a
printout of
an IR
spectrum.
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A sample of a printout of an IR spectrum.
61. 9/4/2021
61
Cloudy plates must be polished to return them to a
transparent condition.
To polish cloudy windows, rotate salt plate on
polishing cloth.
66. Temperature sensitive capacitors
Triglycine sulfate (TGS)
Lithium tantalate (LiTaO3)
Lithium niobate (LiNbO3)
Materials have large (dipole)/T
Response times of 1 ms or less (fast for
IR detectors)
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67. Essentially a Xe gas thermometer
Expensive, not better than other detectors
in near to mid IR
Very useful in far IR
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68. Monochromator
after sample
Low frequency
chopper (10 min–1)
Works on nulling
principle: reference
beam attenuated to
match sample
beam
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70
The heart of the FTIR is a Michelson interferometer
The mirror moves at a fixed rate. Its position is determined
accurately by counting the interference fringes of a collocated
Helium-Neon laser.
The Michelson interferometer splits a beam of radiation into
two paths having different lengths, and then recombines
them.
A detector measures the intensity variations of the exit
beam as a function of path difference.
A monochromatic source would show a simple sine wave of
intensity at the detector due to constructive and destructive
interference as the path length changes
71. How we “decode” the complex
interferogram
1. Multiply interferogram by cos2pft (a cosine
wave of frequency f)
2. Integrate result
3. Repeat for all desired f values
Mathematically speaking:
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71
ftdt
t
P
P p
n 2
cos
72. If a signal “encoded” in the interferogram matches the
frequency f, the integral will be large
If a signal “encoded” in the interferogram does not
match the frequency f, the integral will be small
A plot of the integral values vs. f yields an absorption
spectrum (Voila!)
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73. The magnitude of the signal increases as the number
of scans, N
The magnitude of noise increases as the square root
of the number of scans, N
Therefore, S/N increases as N
Signal averaging enables the study of dilute solutions
Consider:
dispersive instrument: 600 s/spectrum
FT instrument: 1 s/spectrum
In 600 scan an FT instrument can improve S/N by 600 25-
fold
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74. In general:
1. Lighter atoms will allow the oscillation to be faster – higher energy
2. This is especially true of bonds to hydrogen – C-H, N-H and O-H
3. Stronger bonds will have higher energy oscillations
1. Triple bonds > double bonds > single bonds in energy
Energy/n of oscillation
75. The IR Spectrum – The detection of different bonds
As opposed to chromatography or other spectroscopic
methods, the area of a IR band (or peak) is not directly
proportional to concentration of the functional group producing
the peak
1. The intensity of an IR band is affected by two primary factors:
Whether the vibration is one of stretching or bending
Electro negativity difference of the atoms involved in the
bond
For both effects, the greater the change in dipole
moment in a given vibration or bend, the larger the peak.
The greater the difference in electro negativity between
the atoms involved in bonding, the larger the dipole
moment
Typically, stretching will change dipole moment more
than bending
76. The IR Spectrum – The detection of different bonds
It is important to make note of peak intensities to show the
effect of these factors:
• Strong (s) – peak is tall, transmittance is low (0-35 %)
• Medium (m) – peak is mid-height (75-35%)
• Weak (w) – peak is short, transmittance is high (90-75%)
• * Broad (br) – if the Gaussian distribution is abnormally
broad
(*this is more for describing a bond that spans many
energies)
Exact transmittance values are rarely recorded
Infrared Spectroscopy
77. Infrared Group Analysis
A. General
1. The primary use of the IR is to detect functional groups
Because the IR looks at the interaction of the EM spectrum
with actual bonds, it provides a unique qualitative probe into
the functionality of a molecule, as functional groups are
merely different configurations of different types of bonds
2. Since most “types” of bonds in covalent molecules have
roughly the same energy, i.e., C=C and C=O bonds, C-H
and N-H bonds they show up in similar regions of the IR
spectrum
3. Remember all organic functional groups are made of
multiple bonds and therefore show up as multiple IR bands
(peaks)
78. No two molecules will give exactly the same IR spectrum
(except enantiomers)
Simple stretching: 1600-3500 cm-1
Complex vibrations: 400-1400 cm-1, called the
“fingerprint region”
78
Baseline
Absorbance/
Peak
80. Bonds with more s character absorb at a
higher frequency
• sp3 C-H, just below 3000 cm-1 (to the right)
• sp2 C-H, just above 3000 cm-1 (to the left)
• sp C-H, at 3300 cm-1
80
81. 1. Alkanes – combination of C-C and C-H bonds
• C-C stretches and bends 1360-1470 cm-1
• CH2-CH2 bond 1450-1470 cm-1
• CH2-CH3 bond 1360-1390 cm-1
• sp3 C-H between 2800-3000 cm-1
Octane
(w – s) (m)
83. 2. Alkenes – addition of the C=C and vinyl C-H bonds
• C=C stretch at 1620-1680 cm-1 weaker as
substitution increases
• vinyl C-H stretch occurs at 3000-3100 cm-1
• The difference between alkane, alkene or alkyne
C-H is important! If the band is slightly above 3000
it is vinyl sp2 C-H or alkynyl sp C-H if it is below it
is alkyl sp3 C-H
1-Octene
(w – m)
(w – m)
85. 3. Alkynes – addition of the C=C and vinyl C-H
bonds
• C≡C stretch 2100-2260 cm-1; strength depends
on asymmetry of bond, strongest for terminal
alkynes, weakest for symmetrical internal
alkynes
• C-H for terminal alkynes occurs at 3200-3300
cm-1
• Internal alkynes ( R-C≡C-R ) would not have this
band
1-Octyne
(m – s)
(w-m)
87. 4. Aromatics
• Due to the delocalization of e- in the ring, C-C bond
order is 1.5, the stretching frequency for these
bonds is slightly lower in energy than normal C=C
• These show up as a pair of sharp bands, 1500 &
1600 cm-1, (lower frequency band is stronger)
• C-H bonds off the ring show up similar to vinyl C-H
at 3000-3100 cm-1
Ethyl benzene
(w – m) (w – m)
88. 4. Aromatics
• If the region between 1667-2000 cm-1 (w) is free of interference (C=O
stretching frequency is in this region) a weak grouping of peaks is
observed for aromatic systems
• Analysis of this region, called the overtone of bending region, can lead
to a determination of the substitution pattern on the aromatic ring
Monosubstituted
1,2 disubstituted (ortho or o-)
1,2 disubstituted (meta or m-)
1,4 disubstituted (para or p-)
G
G
G
G
G
G
G
89. 5. Unsaturated Systems – substitution patterns
• The substitution of aromatics and alkenes can also be discerned
through the out-of-plane bending vibration region
• However, other peaks often are apparent in this region. These
peaks should only be used for reinforcement of what is known or
for hypothesizing as to the functional pattern.
R
C
H
C
R
C
H
CH2
R
C
H
C
R
C
R
CH2
R
C
R
C
R
H
R
H
R
H
985-997
905-915
cm-1
960-980
665-730
885-895
790-840
R
R
R
R
R
R
R
cm-1
730-770
690-710
735-770
860-900
750-810
680-725
800-860
90. 6. Ethers – addition of the C-O-C asymmetric
band and vinyl C-H bonds
• Show a strong band for the antisymmetric C-
O-C stretch at 1050-1150 cm-1
• Otherwise, dominated by the hydrocarbon
component of the rest of the molecule
Diisopropyl ether
(s)
91. 7. Alcohols
• Strong, broad O-H stretch from 3200-3400 cm-1
• Like ethers, C-O stretch from 1050-1260 cm-1
• Band position changes depending on the alcohols
substitution: 1° 1075-1000; 2° 1075-1150; 3°
1100-1200; phenol 1180-1260
• The shape is due to the presence of hydrogen
bonding
1-butanol
(m– s)
br
(s)
92. Both of these occur around 3300 cm-1, but they
look different
• Alcohol O-H, broad with rounded tip
• Secondary amine (R2NH), broad with one sharp
spike
• Primary amine (RNH2), broad with two sharp
spikes
• No signal for a tertiary amine (R3N)
92
94. 8. Amines - Primary
• Shows the –N-H stretch for NH2 as a doublet
between 3200-3500 cm-1 (symmetric and anti-
symmetric modes)
• -NH2 has deformation band from 1590-1650
cm-1
• Additionally there is a “wag” band at 780-820
cm-1 that is not diagnostic
2-aminopentane
(w) (w)
96. 9. Amines – Secondary
• N-H band for R2N-H occurs at 3200-3500
cm-1 as a single sharp peak weaker than
–O-H
• Tertiary amines (R3N) have no N-H bond
and will not have a band in this region
pyrrolidine
(w – m)
97. Pause and Review
• Inspect the bonds to H region (2700 – 4000 cm-1)
• Peaks from 2850-3000 are simply sp3 C-H in most organic
molecules
• Above 3000 cm-1 Learn shapes, not wavenumbers!:
Broad U-shape peak
-O—H bond
V-shape peak
-N—H bond for 2o
amine (R2N—H)
Sharp spike
-C≡C—H bond
W-shape peak
-N—H bond for 1o
amine (RNH2)
3000 cm-1
Small peak shouldered
just above 3000 cm-1
C=C—H or Ph—H
98. The C=O bond of simple ketones, aldehydes, and
carboxylic acids absorb around 1710 cm-1
Usually, it’s the strongest IR signal
Carboxylic acids will have O-H also
Aldehydes have two C-H signals around 2700 and
2800 cm-1
98
99. 10.Aldehydes
• C=O (carbonyl) stretch from 1720-1740 cm-1
• Band is sensitive to conjugation, as are all
carbonyls (upcoming slide)
• A highly unique sp2 C-H stretch appears as a
doublet, 2720 & 2820 cm-1 called a “Fermi
doublet”
Cyclohexyl carboxaldehyde
(w-m)
(s)
101. 11.Ketones
• Simplest of the carbonyl compounds as
far as IR spectrum – carbonyl only
• C=O stretch occurs at 1705-1725 cm-1
3-methyl-2-pentanone
(s)
103. 12.Esters
• C=O stretch at 1735-1750 cm-1
• Strong band for C-O at a higher frequency
than ethers or alcohols at 1150-1250 cm-1
Ethyl pivalate
(s)
(s)
104. 13.Carboxylic Acids:
• Gives the messiest of IR spectra
• C=O band occurs between 1700-1725 cm-1
• The highly dissociated O-H bond has a broad band from
2400-3500 cm-1 covering up to half the IR spectrum in
some cases
4-phenylbutyric acid
(w – m)
br
(s) (s)
105. This O-H absorbs broadly, 2500-3500
cm-1, due to strong hydrogen bonding
10
5
106. Conjugation of C=O with C=C lowers the stretching
frequency to ~1680 cm-1
The C=O group of an amide absorbs at an even lower
frequency, 1640-1680 cm-1
The C=O of an ester absorbs at a higher frequency,
~1730-1740 cm-1
Carbonyl groups in small rings (5 C’s or less) absorb at an
even higher frequency
10
6
107. 14.Acid anhydrides
• Coupling of the anhydride though the ether
oxygen splits the carbonyl band into two with a
separation of 70 cm-1
• Bands are at 1740-1770 cm-1 and 1810-1840 cm-1
• Mixed mode C-O stretch at 1000-1100 cm-1
Propionic anhydride
O
O O
(s) (s)
108. 15.Acid halides
• Clefted band at 1770-1820 cm-1 for C=O
• Bonds to halogens, due to their size (see
Hooke’s Law derivation) occur at low
frequencies, only Cl is light enough to have
a band on IR, C-Cl is at 600-800 cm-1
Propionyl chloride
Cl
O
(s)
(s)
109. 16.Amides
• Display features of amines and carbonyl
compounds
• C=O stretch at 1640-1680 cm-1
• If the amide is primary (-NH2) the N-H stretch
occurs from 3200-3500 cm-1 as a doublet
• If the amide is secondary (-NHR) the N-H stretch
occurs at 3200-3500 cm-1 as a sharp singlet
pivalamide
NH2
O
(m – s) (s)
111. C - N absorbs around 1200 cm-1
C = N absorbs around 1660 cm-1 and is much stronger
than the C = C absorption in the same region
C N absorbs strongly just above 2200 cm-1. The
alkyne C C signal is much weaker and is just below
2200 cm-1
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112. 17.Nitro group (-NO2)
• Proper Lewis structure gives a bond order of
1.5 from nitrogen to each oxygen
• Two bands are seen (symmetric and
asymmetric) at 1300-1380 cm-1 and 1500-
1570 cm-1
• This group is a strong resonance withdrawing
group and is itself vulnerable to resonance
effects
2-nitropropane
N
O
O
(s) (s)
113. 18. Nitriles (the cyano- or –C≡N group)
• Principle group is the carbon nitrogen
triple bond at 2100-2280 cm-1
• This peak is usually much more
intense than that of the alkyne due to
the electronegativity difference
between carbon and nitrogen
propionitrile
N
C
(s)
115. Effects on IR bands
1. Conjugation – by resonance, conjugation lowers the energy of a double or triple
bond. The effect of this is readily observed in the IR spectrum:
• Conjugation will lower the observed IR band for a carbonyl from 20-40 cm-1
provided conjugation gives a strong resonance contributor
• Inductive effects are usually small, unless coupled with a resonance
contributor (note –CH3 and –Cl above)
O
O
1684 cm-1
1715 cm-1
C=O C=O
C
H3C
O
X X = NH2 CH3 Cl NO2
1677 1687 1692 1700 cm-1
H2N C CH3
O
Strong resonance contributor
vs.
N
O
O
C
CH3
O
Poor resonance contributor
(cannot resonate with C=O)
116. Effects on IR bands
2. Steric effects – usually not important in IR spectroscopy, unless they reduce
the strength of a bond (usually p) by interfering with proper orbital overlap:
• Here the methyl group in the structure at the right causes the carbonyl
group to be slightly out of plane, interfering with resonance
3. Strain effects – changes in bond angle forced by the constraints of a ring will
cause a slight change in hybridization, and therefore, bond strength
• As bond angle decreases, carbon becomes more electronegative, as well
as less sp2 hybridized (bond angle < 120°)
O
C=O: 1686 cm-1
O
C=O: 1693 cm-1
CH3
O O O O O
1815 cm-1
1775 cm-1
1750 cm-1
1715 cm-1
1705 cm-1
117. Effects on IR bands
4. Hydrogen bonding
• Hydrogen bonding causes a broadening in the band due to the creation of
a continuum of bond energies associated with it
• In the solution phase these effects are readily apparent; in the gas phase
where these effects disappear or in lieu of steric effects, the band appears
as sharp as all other IR bands:
Gas phase spectrum of
1-butanol
Steric hindrance to H-bonding
in a di-tert-butylphenol
• H-bonding can interact with other functional groups to lower frequencies
OH
C=O; 1701 cm-1
O
O
H
119. IR alone cannot determine a structure
Some signals may be ambiguous
The functional group is usually indicated
The absence of a signal is definite proof that the
functional group is absent
Correspondence with a known sample’s IR
spectrum confirms the identity of the compound
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120. IR identifies the components of a sample (liquid, solid or
gas).
Infrared (IR) spectrometers measure the interaction of IR
radiation with samples.
The FTIR spectrometer measures the frequencies at which
the samples absorb the radiation, and the intensities of the
absorptions.
Intensity and frequency of samples absorption are
depicted in a two-dimensional plot called a spectrum.
Intensity is generally reported in terms of absorbance - the
amount of light absorbed by a sample, or percent
transmittance – i.e. the amount of light, which passes
through it.
What makes up an unknown sample, and how much of
each component is present in that sample, can be valuable
information supplied by this technique. Its many
applications include research and development of new
products.
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