C8953
NMR structural analysis - seminar
Vector model of NMR experiments + 1D spectra
Jan Novotný
novotnyjan@mail.muni.cz
March 15, 2017
1
H NMR spectrum of naringenine in d6-acetone
1
H NMR spectrum of naringenine in d6-acetone
1
2
3
5a,b
4
6
8
9
7
9
1
7
2
3
6
8
4
5a,b
Basics of 1D FT spectroscopy
Draw the expected vector model of following simple pulse sequences
(right-handed system, B0 in +z direction:)
90−x :
90+y − Ωτ = π/2:
90+x − Ωτ = π/3 − 180+x − Ωτ = π/3:
90+x − Ωτ = π/3 − 180+y − Ωτ = π/3:
Basics of 1D FT spectroscopy
Draw the expected vector model of following simple pulse sequences
(right-handed system, B0 in +z direction:)
90−x : +y
90+y − Ωτ = π/2: +x → +y
90+x − Ωτ = π/3 − 180+x − Ωτ = π/3:
−y → −y ∗ cos(60) + x ∗ sin(60) → +y ∗ cos(60) + x ∗ sin(60) → +y
90+x − Ωτ = π/3 − 180+y − Ωτ = π/3:
−y → −y ∗ cos(60) + x ∗ sin(60) → −y ∗ cos(60) − x ∗ sin(60) → −y
Basics of 1D FT spectroscopy
Draw FT representation of attached FID
records (reciever is located in the +y
direction):
Basics of 1D FT spectroscopy
Draw FT representation of attached FID
records (reciever is located in the +y
direction):
Basics of 1D FT spectroscopy
Draw FT representation of vector models
(in rotating frame, receiver is located in the
+y direction):
Basics of 1D FT spectroscopy
Draw FT representation of vector models
(in rotating frame, receiver is located in the
+y direction):
Heteronuclear spin echo of 13
C-1
H3 group
By using vector diagrams determine the result of attached pulse sequence. First
realize what is the evolution of 13C signal resulting from offset? CPD=composite pulse
decoupling
Heteronuclear spin echo of 13
C-1
H3 group
By using vector diagrams determine the result of attached pulse sequence. First
realize what is the evolution of 13C signal resulting from offset? CPD=composite pulse
decoupling
APT - Attached Proton Test
based on heteronuclear spin echo
t1 = 1/1JCH
13
C signals are differentiated according to the number of directly
bound 1
H
Cq, CH2 positive
CH, CH3 negative
Evolution of signal governed by the value of 1
JCH =⇒ reflected by
the intensity of APT signal
90x 180y
180
H-1
C-13 acq
dec
t1
-1
-0.5
0
0.5
1
0 0.5 1 1.5 2
Relativeintensity
t1 (1/1
JCH)
Cq
CH
CH2
CH3
13
C APT Cinnamic acid
13
C APT Cinnamic acid
9 DMF
7
1
2,6 3,5
4 8
Notes:
C9, C1 positive
quaternary
C7 deshielded by -M
effect of carboxyl
group + in
neighbourhood of
aromatic system
equivalent C2/6,
C3/5 in aromatic
region, para C4 less
sensitive
13
C APT of Nicotine
13
C APT of Nicotine
11
10
9
127
3
2,6
54
Notes:
C2, C6 CH negative
connected to N
C3 quaternary, C4
more deshielded
C7 tertiary carbon,
in neighbourhood of
aromatic system
and N
C9 secondary, close
to N; C12 primary
attached to N
C11 connected to
tertiary carbon
13
C APT 4
Cq Cq CH2
13
C APT 4
Cq Cq
2 6 4
8
13
12
5 11
15
14
1'
CH2
1
H-13
C DEPT spectrum
http://www.akoci.uni-hannover.de/ak-duddeck/pdf/pdf-master-wirk-nat
1
H-13
C DEPT spectrum
+CH
-CH2, +CH, +CH3
+all
93
1,2 4
10
8
7
3,6,53
94
http://www.akoci.uni-hannover.de/ak-duddeck/pdf/pdf-master-wirk-nat
Next topic
2D spectroscopy