C8953
NMR strukturní analýza
semináˇr
Introduction to heteronuclear correlations
Jan Novotný. Kateˇrina Peterková
novotnyjan@mail.muni.cz
April 10, 2019
Polarization transfer
� bigger population diffrenece of 1H nucleus is transfered via J-coupling to less
sensitive nucleus X (13C, 15N)
� fundamental building block of heteronucler correlation experiments: in 2D-HX
experiment each crosspeak manifests interaction of H and X nucleus coupled
trough bonds
� Task: Draw the evolution of magnetization during basic INEPT pulse
sequence. Consider C-H interacting pair.
HMQC (Heteronuclear Multiple Quantum Correlation)
HSQC (Heteronuclear Single Quantum Correlation)
correlate 1
H-X (X=13
C, 15
N,...) based on
1
JHX
HMQC (a)
+ more robust experiment
+ change of parameters - HMBC
- lower sensitivity and worse resolution
HSQC (b)
+ better resolution, sensitivity
+ part of more complex mutlidimensional
experiments
- less robust
H-1
X
acq
dec
90
90 90
180
1/2J 1/2J
t1
(a)
H-1
X
acq
dec
t1
d d d d
d = 1/4J
(b)
Practical notes 1H-X HSQC
� resolution of overlaps
� routine experiments to control biomolecular sample
� easy identification of geminal protons
� indirect determination of protons bonded to NMR inactive heteroatom
� heteronuclear correlation ⇒ no diagonal crosspeak, no symmetry
� X decoupled during acquisition ⇒ singlet crosspeak
HMBC(Heteronuclear Multiple-Bond Correlation)
heteronuclear correlation based on long-range H-X spin-spin
interaction( n
JHX , n>1 )
� utilizes polarization transfer from H through 2-5 bonds on heteroatom ( 13C, 15N )
� allows to detect quaternary heteroatoms (Cq) or connect signals among isolated
spin systems
HMBC
correct settings of d1, d2 fo evolution of J-coupling necessary
� d1=1/2∗1JC−H - (120-180 Hz)
� d2=1/2∗2−5JC−H - (3-12 Hz)
1
H
X
acq
t1/2 t1/2
90 90
90 180
d1 d2
90
1H-13C HMBC + 1H-13C HSQC
H4-C4
H2-C2
H10-C10
H9-C9
H7-C7
H8-C8
H7-C9
H7-C8
H7-C10
H9-C10
H2-C7
H4-C6
H2-C6
H4-C1 H7-C1
H7-C2
H9-C1
Folic Acid: 1H 1D
N
N
N
N
O
NH2
N
H
O
O
O
–
O
–
O
NH
1
2
3
4
5
6
7
8
9
10 11 12
13
14
15
16
17
18
19
20
21
22
23
2425
Folic Acid: 13C 1D
N
N
N
N
O
NH2
N
H
O
O
O
–
O
–
O
NH
1
2
3
4
5
6
7
8
9
10 11 12
13
14
15
16
17
18
19
20
21
22
23
2425
Folic Acid: 1H-13C HMBC
8
8
6
6
4
4
2
2
δ2 - 1H (ppm)
150 150
100 100
50 50
δ1-13C(ppm)
N
N
N
N
O
NH2
N
H
O
O
O
–
O
–
O
NH
1
2
3
4
5
6
7
8
9
10 11 12
13
14
15
16
17
18
19
20
21
22
23
2425
Folic Acid: 1H-15N HMBC
8
8
6
6
4
4
2
2
δ2 - 1
H (ppm)
300 300
250 250
200 200
150 150
100 100
δ1-15
N(ppm)
N
N
N
N
O
NH2
N
H
O
O
O
–
O
–
O
NH
1
2
3
4
5
6
7
8
9
10 11 12
13
14
15
16
17
18
19
20
21
22
23
2425
Riboflavine: 1H-13C HMBC + HSQC
8
8
7
7
6
6
5
5
4
4
3
3
δ2 - 1H (ppm)
150 150
100 100
50 50
δ1-13
C(ppm)
5a
9a
6
9
7
8
4a
10a
N
5
N
10
NH
3
2
4
N
1
13
14
15
16
17
OH
OH
OH
OH
O
O
CH3
11
CH3
12
Riboflavine: DQF-COSY
8
8
6
6
4
4
2
2
δ2 - 1H (ppm)
8 8
7 7
6 6
5 5
4 4
3 3
δ1-1
H(ppm)
5a
9a
6
9
7
8
4a
10a
N
5
N
10
NH
3
2
4
N
1
13
14
15
16
17
OH
OH
OH
OH
O
O
CH3
11
CH3
12
Next session:
Complex exercises