C8953
NMR strukturní analýza
semináˇr
Heteronuclear correlations
Jan Novotný
176003@is.muni.cz
March 29, 2023
1D 13C NMR
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
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
1H-13C HMBC + 1H-13C HSQC
H7-C9
H7-C8
H7-C10
H9-C10
H2-C7
H4-C6
H2-C6
H4-C1 H7-C1
H7-C2
H9-C1
H4-C4
H2-C2
H10-C10
H9-C9
H7-C7
H8-C8
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-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
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
N20-H23'
N20-H23''
N20-H21
N12-H21
N12-H14,18N12-H15,17
N7-H8
N10-H8
N7-H11
N10-H11
Folic Acid: 1H-13C HMBC
8
8
6
6
4
4
2
2
δ2 - 1
H (ppm)
150 150
100 100
50 50
δ1-13
C(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-13C HMBC
Next session:
Complex tasks