This document provides an introduction and overview of C-13 nuclear magnetic resonance (NMR) spectroscopy. It discusses the basic principles of NMR, including nuclear spin, resonance frequency, chemical shifts, spin relaxation, scalar coupling, and other concepts. Examples of typical chemical shift ranges are given for different types of carbon environments. Predictions of chemical shifts are demonstrated using known substituent effects. Solvent chemical shift references are also provided.
Two dimensional Nuclear Magnetic Resonance (2D NMR) refers to a set of multi pulse techniques which were introduced to overcome the complex spectra obtained with NMR.
It is a set of NMR methods which give data plotted in a space defined by two frequency axes rather than one.
Introduction & Definition, Theory, instrumentation, Continuous – wave (CW) instrument, The pulsed Fourier Transform [FT] instrument, Solvents, Chemical shift
i. Shielding and de-shielding
ii. Factors affecting chemical shift
Two dimensional Nuclear Magnetic Resonance (2D NMR) refers to a set of multi pulse techniques which were introduced to overcome the complex spectra obtained with NMR.
It is a set of NMR methods which give data plotted in a space defined by two frequency axes rather than one.
Introduction & Definition, Theory, instrumentation, Continuous – wave (CW) instrument, The pulsed Fourier Transform [FT] instrument, Solvents, Chemical shift
i. Shielding and de-shielding
ii. Factors affecting chemical shift
NMR stands for Nuclear Magnetic Resonance. It is a scientific technique used to study the structure, composition, and dynamics of molecules. In NMR spectroscopy, a sample is placed in a strong magnetic field and subjected to radiofrequency radiation. The atomic nuclei in the sample, particularly those with a nonzero spin, absorb and re-emit electromagnetic radiation at specific frequencies. By measuring the frequencies at which the nuclei resonate, valuable information about the chemical environment and connectivity of the atoms in the molecule can be obtained. It is a powerful tool for chemists and other scientists working in fields related to molecular analysis and characterization.
Similarities and differences between 1D and 2D NMR techniques are broadly illustrated here:
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
NMR stands for Nuclear Magnetic Resonance. It is a scientific technique used to study the structure, composition, and dynamics of molecules. In NMR spectroscopy, a sample is placed in a strong magnetic field and subjected to radiofrequency radiation. The atomic nuclei in the sample, particularly those with a nonzero spin, absorb and re-emit electromagnetic radiation at specific frequencies. By measuring the frequencies at which the nuclei resonate, valuable information about the chemical environment and connectivity of the atoms in the molecule can be obtained. It is a powerful tool for chemists and other scientists working in fields related to molecular analysis and characterization.
Similarities and differences between 1D and 2D NMR techniques are broadly illustrated here:
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
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
For UG/PG students of All Engineering (B Tech/B E) branches, Chemistry, Food Technology, Biochemistry, Biotechnology.
The video lecture link of the presentation is
https://www.youtube.com/watch?v=bFPhvnW8T18&t=99s
Richard's aventures in two entangled wonderlandsRichard 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.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
1. C13 NUCLEAR
MAGNETIC RESONANCE (NMR)
, DEPT, COSY & NOESY
Sujitlal Bhakta
Department of Chemistry
RavenshawUniversity
Cuttack, Odisha, 753 003
2. Introduction to C-13 NMR
13C occurs naturally as 1.11% of total C and the NMR signal is
weaker than 1H. Fourier Transform NMR is used to collect a
spectrum
C13 resonances occur from 0 to 220 ppm (δ).
13C peaks are split by the attached hydrogens.
3. Nuclei with an odd mass or odd atomic number have "nuclear spin"
(in a similar fashion to the spin of electrons). This includes 1H and 13C(butnot 12C).
The spins of nuclei are sufficiently different that NMR experiments can be
sensitive for only one particular isotope of one particular element. The NMR
behaviour of 1H and 13C nuclei has been exploited by organic chemist since they
provide valuable information that can be used to deduce the structure of organic
compounds. These will be the focus of our attention.Since a nucleus is a
Charged particle in motion, it will develop a magnetic field. 1H and 13C have nuclear
spins of 1/2 and so they behave
in a similar fashion to a simple,
tiny bar magnet. In the absence
of a magnetic field, these
are randomly oriented but when a
field is applied they line up
parallel to the applied field,
either spin aligned or spin
opposed. The more highly
populated state is the
lower energy spin state spin
aligned situation. Two schematic
representations of these
arrangements are shown below:
BASIC PRINCIPLES OF NMR
4. Nuclear Magnetic Resonance
Nuclear spin
m = g I h
m - magnetic moment
g - gyromagnetic ratio
I - spin quantum number
h - Planck’s constant
m
I is a property of the nucleus
Mass # Atomic # I
Odd Even or odd 1/2, 3/2, 5/2,…
Even Even 0
Even Odd 1, 2, 3
As an exercise determine I for each of
the following 12C, 13C, 1H, 2H, 15N .
5. Nucleus Spin
Quantum
Number
(I)
Natural
Abundanc
e (%)
Gyromagnetic
Ratio
(10-7 rad/T
sec)
Sensitivity†
(% vs. 1H)
Electric
Quadrupu
le
Moment
(Q)
(e·1024
cm2)
1H
2H
13C
15N
19F
31P
1/2
1
1/2
1/2
1/2
1/2
99.9844
0.0156
1.108
0.365
100
100
26.7520
4.1067
6.7265
-2.7108
25.167
10.829
100.0
0.965
1.59
0.104
83.3
6.63
—————
0.00277
—————
—————
—————
—————
Nuclear Magnetic Resonance
6. Bo
w w = g Bo = n/2p
w - resonance frequency
in radians per second,
also called Larmor frequency
n - resonance frequency
in cycles per second, Hz
g - gyromagnetic ratio
Bo - external magnetic
field (the magnet)
Apply an external magnetic field
(i.e., put your sample in the magnet)
z
m
m
w
Spin 1/2 nuclei will have two
orientations in a magnetic field
+1/2 and -1/2.
8. Bo = 0 Bo > 0
Randomly oriented Highly oriented
Bo
Ensemble of Nuclear Spins
N
S
Each nucleus behaves like
a bar magnet.
9. The net magnetization vector
z
x
y
w
w
z
x
y
Mo - net magnetization
vector allows us to
look at system as a whole
z
x
w
one nucleus
many nuclei
10. Bo = 0 Bo > 0
E DE
Allowed Energy States for a
Spin 1/2 System
antiparallel
parallel
DE = g h Bo = h n
-1/2
+1/2
Therefore, the nuclei will absorb light with energy DE resulting in
a change of the spin states.
11. Energy of Interaction
DE = g h Bo = h n
The frequency, n, corresponds to light in the
radiofrequency range when Bo is in the Teslas.
This means that the nuclei should be able to absorb
light with frequencies in the range of 10’s to 100’s of
megaherz.
Note: FM radio frequency range is from ~88MHz to
108MHz. 77Se, g = 5.12x107 rad sec-1 T-1
n = g Bo/2p
14. Free Induction Decay
The signals decay away due to interactions with the surroundings.
A free induction decay, FID, is the result.
Fourier transformation, FT, of this time domain signal
produces a frequency domain signal.
FT
Time
Frequency
15. Spin Relaxation
There are two primary causes of spin relaxation:
Spin - lattice relaxation, T1, longitudinal relaxation.
Spin - spin relaxation, T2, transverse relaxation.
lattice
16. Nuclear Overhauser Effect
Caused by dipolar coupling between nuclei.
The local field at one nucleus is affected by the
presence of another nucleus. The result is a mutual
modulation of resonance frequencies.
N
S
N
S
17. Nuclear Overhauser Effect
The intensity of the interaction is a function of the distance
between the nuclei according to the following equation.
I = A (1/r6)
I - intensity
A - scaling constant
r - internuclear distance
1H 1H
r1,2
1 2
1H
3
r1,3 r2,3
Arrows denote cross relaxation pathways
r1,2 - distance between protons 1 and 2
r2,3 - distance between protons 2 and 3
The NOE provides a link between an
experimentally measurable quantity, I, and
internuclear distance.
NOE is only observed up to ~5Å.
18. Scalar J Coupling
Electrons have a magnetic moment and are spin 1/2 particles.
J coupling is facilitated by the electrons in the bonds
separating the two nuclei. This through-bond interaction
results in splitting of the nuclei into 2I + 1states. Thus, for a
spin 1/2 nucleus the NMR lines are split into 2(1/2) + 1 = 2 states.
1H
12
C 12
C
1H
Multiplet = 2nI + 1
n - number of identical adjacent nuclei
I - spin quantum number
19. Scalar J Coupling
The magnitude of the J coupling is dictated by the torsion
angle between the two coupling nuclei according to the
Karplus equation.
C
C
H
H
H
H
q
J = A + Bcos(q) + C cos2(q)
A = 1.9, B = -1.4, C = 6.4
0
2
4
6
8
10
12
0 100 200 300 400
q
3J
Karplus Relation
A, B and C on the substituent
electronegativity.
20. Torsion Angles
Coupling constants can be measured from NMR data.
Therefore, from this experimental data we can use
the Karplus relation to determine the torsion angles, q.
Coupling constants can be measured between most
spin 1/2 nuclei of biological importance,
1H, 13C, 15N, 31P
The most significant limitation is usually sensitivity, S/N.
21. Chemical Shift, δ
The chemical is the most basic of measurements in NMR.
The Larmor frequency of a nucleus is a direct result of the nucleus,
applied magnetic field and the local environment.
If a nucleus is shielded from the applied field there is a netreduction if
the magnetic field experienced by the nucleus which results in a lower
Larmor frequency.
d is defined in parts per million, ppm.
13C Chemical shifts are most affected by:
hybridization state of carbon
electronegativity of groups attached to carbon
22. 220 210 200 180 160 140 120 100 80 60 40 20 0
R
C
H
O
R
C
R
O
190-220d
R
C
OR
O
R
C
OH
O
160-190d
R
C
NR2
O
R
C
X
O
110-160d
C C
50-110d
C C
Csp3
Fn
0-50d
sp3C Csp3
4o
--3o
--2o
--1o
TYPICAL CHEMICAL SHIFTS
• 190-220d
– aldehydes, ketones
• 160-190d
– esters, amides, carboxylic acids, acyl halides
• 110-160d
– arenes, alkenes
• 50-110d
– alkynes, sp3C attached to functional groups
• 0-50d
– sp3C-Csp3, where 4o>3o>2o>1o
23. The zero point is defined as the position of absorption of a
standard, tetramethylsilane (TMS):
This standard has only one type of C and only one type of H.
Si
CH3
CH3
CH3
CH3
13C chemical shift
downfield upfield
20406080100120140160180200220 0
CH3
CH2
CH
C X (halogen)
C N
C O
C C
C N
C CC O
13C Chemical shift (d)
TMS
Aromatic C
24. C13 Chemical Shift (d) vs. Electronegativity
-10
0
10
20
30
40
50
60
70
80
90
1.5 2 2.5 3 3.5 4
Electronegativity
C13ChemicalShift
Chemical Shifts
CH3 Si
CH3 C
CH3 N
CH3 O
CH3 F
Electronegative groups attached to the C-H system decrease the electron
density around the protons, and there is less shielding (i.e. deshielding) so
the chemical shift increases.
26. Magnetic Anisotropy
The word "anisotropic" means "non-uniform". So magnetic anisotropy means
that there is a "non-uniform magnetic field". Electrons in π systems
(e.g. aromatics, alkenes, alkynes, carbonyls etc.) interact with the applied field
which induces a magnetic field that causes the anisotropy. As a result, the
nearby protons will experience 3 fields: the applied field, the shielding field of
the valence electrons and the field due to the π system. Depending on the
position of the proton in this third field, it can be either shielded (smaller d) or
deshielded (larger d), which implies that the energy required for, and the
frequency of the absorption will change.
27. Solvent
1H NMR
Chemical Shift
13C NMR
Chemical Shift
Acetic Acid 11.65 (1) , 2.04 (5) 179.0 (1) , 20.0 (7)
Acetone 2.05 (5) 206.7 (13) , 29.9 (7)
Acetonitrile 1.94 (5) 118.7 (1) , 1.39 (7)
Benzene 7.16 (1) 128.4 (3)
Chloroform 7.26 (1) 77.2 (3)
Dimethyl Sulfoxide 2.50 (5) 39.5 (7)
Methanol 4.87 (1) , 3.31 (5) 49.1 (7)
Methylene
Chloride
5.32 (3) 54.00 (5)
Pyridine
8.74 (1) , 7.58 (1) , 7.22
(1)
150.3 (1) , 135.9 (3) ,
123.9 (5)
Water (D2O) 4.8
NMR Solvent Signals
The
chemical
shifts (d)of
solvent
signals
observed
for1H NMR
and
13C NMR
spectra
Are listed
in the
following
table.
The
multiplicity
is shown in
parentheses
as 1 for
singlet, 2 for
doublet,
3 for triplet,
etc.
28. Solvent Chemical Shift of H2O (or HOD)
Acetone 2.8
Acetonitrile 2.1
Benzene 0.4
Chloroform 1.6
Dimethyl Sulfoxide 3.3
Methanol 4.8
Methylene Chloride 1.5
Pyridine 4.9
Water (D2O) 4.8
Signals for water occur at different frequencies in 1H NMR spectra depending on
the solvent used. Listed below are the chemical shift positions of the water signal
in several common solvents. Note that H2O is seen in aprotic solvents, while HOD
is seen in protic solvents due to exchange with the solvent deuteriums.
NMR Water Signals
30. Predicted Chemical Shifts of
Ca and Cb
a
b
Ca = (-2.5) + 4(9.1) + 9.4 + 2(-2.5) + 3(-1.5) + (-8.4) =25.4 ppm
Cb = (-2.5) + 2(9.1) + 5(9.4) +(-7.2) + (-2.5) =53.0 ppm
base g 4o(1o) 4o(2o)
base 2o(4o) 2o(3o)
35. 13C Off-resonance & Broadband
decoupled spectra
Broadband
Off-resonance
Off-resonance decoupling eliminates interactions of hydrogens on
adjacent carbons.
Broadband decoupling eliminates splitting of C by Hs attached to that
C.
However, proton decoupled (broadband) spectra are not split by H.
38. Summary
There are three primary NMR tools
used to obtain structural information
Nuclear Overhauser effect - internuclear distances
J Coupling - torsion angles
Chemical shift - local nuclear environment
(Chemical exchange can also be monitored by NMR.)
39. Distortionless enhancement by polarization transfer
(DEPT) spectra permit identification of CH3, CH2, and CH
carbon atoms.
DEPT 45 shows 1o, 2o,and 3o carbons. So any broadband
peak not in DEPT 45 is 4o.
DEPT 90 shows only 3o carbons.
DEPT 135 shows 1o and 3o carbons as positive peaks and 2o
carbons as negative peaks.
DEPT
In DEPT, a second transmitter irradiates 1H during the
sequence, which affects the appearanceof the 13Cspectrum.
some 13C signals stay the same
some 13C signals disappear
some 13C signals are inverted
40. DEPT: Distortionless Enhancement by Polarization Transfer
Heteronuclear expt.
Detection: 13C
Distinguish
CH, CH2, CH3
By suitable combination of
q=45, 90 & 135 spectra
All CH’s
Only CH
CH & CH3up
CH2 down
41. DEPT Spectra
normal C-13 spectrum
DEPT-45
DEPT-90
DEPT-135
C
CH CH2 CH3
Quaternary carbons (C) do not show up in DEPT.
CH and CH3 unaffected
C and C=O nulled
CH2 inverted
43. COSY & NOESY
COSY- Correlation spectroscopy
Gives experimental details of interaction between hydrogens connected
via a covalent bond
NOESY-Nuclear Overhauser effect spectroscopy
Gives peaks between pairs of hydrogen atoms near in space (1.5-5 Å)
(and not necessarily sequence)
C C
H H
C N
H H
HC H
NH
