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Introduction to Nuclear
Magnetic Resonance---NMR
Principle of NMR
without Magnetic
Field
In the Magnetic
Field
B0
Magnetic
Nuclei
In the absence of the field B0, the Magnetic nuclei in the sample are oriented
randomly.In the magnetic field, they must adopt either the aligned orientation(of
lower energy) or the opposed orientation(of higher energy).
without Magnetic
Field
In the Magnetic
Field
B0
Magnetic
Nuclei
Energy
Level
E
hv
In the absence of B0 the magnetic nuclei all have the same energy. When B0
is applied,the aligned and opposed orientations correspond to different
energies,the energy difference, E , having the dimension hv.
without Magnetic
Field
In the Magnetic
Field
B0
Magnetic
Nuclei
E=h
E
When the nuclei(in the magnetic field) are irradiated with radiofrequency(RF)
energy of the appropriate frequency, some of them
undergo transitions from the aligned to the opposed orientations and vice
versa.（Resonance!!!) Resonance condition : W(2兀f )=rB0 f=RF, r=
Field-frequency relationship
Energy
Level
E
300MHz
7.0T
500MHz
11.4T
800MHz
18.8T
Magnetic moment(1)
1 If both the mass number(A) and the atomic number(Z)
are even,
I = 0 (No NMR signal)
12C, 16O
2 If (A) is odd and (Z) is odd or even, I will have halfintegral values.
I =1/2, 3/2, 5/2 etc 1H, 19F, 29Si, 11B(3/2), 17O(5/2)
3 If (A) is even and (Z) is odd, I will have integral value
1,2,3 etc.
14N, 6Li,
Magnetic moment(2)
1H nucleus
1 proton
magnetic
2H nucleus
1 proton
1 neutron
4He nucleus
2 protons
2 neutrons
magnetic
Non-magnetic
12C nucleus
6 proton
6 neutrons
13C nucleus
6 protons
7 neutrons
Non-magnetic
magnetic
Typical Magnetic Isotopes
Isotope Spin
1
H
2
H
13
C
15
N
17
O
19
F
31
P
35
CL
1/2
1
1/2
1/2
5/2
1/2
1/2
3/2
Natural
abundance
(%)
99.98
1.5X10 -2
1.108
0.37
3.7X10 -2
100
100
75.53
Gamma
ratio
Relative to
proton
Absolute
Frequency
at 9.39T
26.75
4.1
6.73
-2.7
-3.6
25.2
10.8
2.6
100
0.965
1.59
0.104
2.91
83
6.63
0.47
100
1.45X10
1.76X10
3.85X10
1.08X10
83
6.63
0.355
400MHz
61.369MHz
100.53MHz
40.514MHz
54.210MHz
376.14MHz
161.85MHz
39.170MHz
Resonance condition: W(2兀f )=rB0
1H : 2x3.14 x400(25.12) = 26.75 x 9.39(25.118)
13C: 2x3.14x100.533(63.13)= 6.73x9.39(63.19)
-4
-2
-4
-3
Sensitivity Table relative to 13C
Block diagram of NMR instrument
RF
Oscillator
RF
Gate
Pulse
Programmer
SCM
RF Power
Amplifier
Probe
Display
Computer
Printer
AD
Converter
Phase Sensitive
detector
Preamplifier
Composition of NMR instrument
ECA 500 NMR
JEOL LTD
The NMR information
1)
2)
3)
4)
5)
Chemical Shift
Spin-Spin Coupling
Intensity(Area) of Signal
Relaxation(T1,T2)
NOE
Chemical Shift
TMS:TetraMethyl-Silane
TMS
Chemical shift
Chemical Shift Table
-CH2- 13C Chemical Shift
Spin-Spin Coupling
CH3-CH2-O-C-CH=CH-CH3
A
C
O
E
D
A
B
B
C
E
D
Intensity(Area) Information
4. 0
3. 5
3. 0
2. 5
2. 0
1. 5
1.02
1.02
0.99
0.99
1.00
1.00
1.02
1.02
1.00
1.00
1.99
1.99
2.03
2.03
2.04
2.02
3.23
3.02
Integration
PP M
1. 0
Various measurement methods
1 dimension (1H,13C,DEPT,…….)
2 dimension (COSY,NOESY,TOCSY,HMBC,HMQC,…)
3 dimension (COSY,NOESY,TOCSY,HMBC,HMQC,…)
4 dimension (COSY,NOESY,TOCSY,HMBC,HMQC,…)
1 dimensional NMR(1D NMR)
50mg samples,Solvent acetone-d6
2 dimensional NMR
Y
X : 1H, 13C, 1H
Y : 1H, 1H, 15N
X
2 dimensional NMR
C:\alice\DATA\AL\Vcosynh.als
Strychnine
DFILE
COMNT
DATIM
EXMOD
OBNUC
OBFRQ
OBSET
OBFIN
POINT
FREQU
CLPNT
TODAT
CLFRQ
SCANS
ACQTM
PD
PW1
PW2
PW3
PI1
PI2
PI3
IRNUC
CTEMP
SLVNT
EXREF
CLEXR
RGAIN
PPM
6
4
2
2
4
C:\alice\DATA\AL\Vcosynh.als
Strychnine
Thu Sep 21 11:03:09 1995
VCOSYNH
1H
270.05 MHz
117.60 KHz
48.8 Hz
512
2162.1 Hz
512
256
2162.1 Hz
3
0.118 sec
1.263 sec
10.2 us
10.2 us
10.0 us
0.463 ms
0.463 ms
1.00 ms
1H
27.2 c
CDCL3
0.00 ppm
0.00 ppm
16
6
PPM
2 dimensional NMR(2 D NMR)
Methylene carbon of B,G,H,J is shown two correlation signals
with Proton , this methylene proton is non-equivalent.
3 dimensional NMR
Y
X
X : 1H
Y: 13C
Z
Z : 31P
Three Dimensional NMR
• 3D NMR is standard with the Eclipse+ NMR spectrometer
4-Dimensional
NMR Data Processing
• Delta’s Standard Multi-Dimensional NMR Data processing tool uses
the same user interface as 1D and 2D data processing
4 dimensional NMR
X
Y
Z
A
X : 1H
Y : 13C
Z : 15N
A : 31P
Application field of NMR
Liquid NMR
Solid NMR
NMR Imaging
Structure elucidation of
natural product ,polymer etc
Stereo- structure elucidation
protein etc
Molecular diffusion
Relaxation measurement
Dynamic measurement
Structure elucidation
Stereo-structure information
Relaxation information
Spin density
Relaxation information
Dynamic information
(Flow imaging)