1. Nuclear Overhauser Effect

2. Nuclear Overhauser Effect (NNOOEE)
• A change in the integrated NMR absorption
intensity of a nuclear spin when the NMR
absorption of another spin is saturated.

3. Nuclear Overhauser
Effect

4. ( s )
I I W 2 W
0
i i + +
1 2 0
0
0
2W W W
I
-
=
-
h =

5. Macromolecules or in viscous solution
W0 dominant, negative NOE at i due to s
Small molecules in non-viscous solution
W2 dominant, positive NOE at i due to s

6. Nuclear Overhauser Effect
Brownian motion and NOE

7. t
( )
( ( ) )
1 6 2 2
w t
i c
t
c
0 6 2 2
w w t
i s c
t
c
2 6 ( 1
( )2 2 )
12
1
2
1
3
+ +
i s c
i c
r
W
r
W
r
W
w w t
µ
+ -
µ
+
µ
When 1/tc >>w0 (or tc
2
w0
2 <<1 ) extreme narrowing limit
W 3 t 2 t 12
t µ c µ c µ
c
1 6 0 6 2 6
r
W
r
W
r

8. When 1/tc >> w0 (or tc
2
w0
2 <<1 )
extreme narrowing limit
W t t t µ 3 c µ 2 c µ
12
c
1 6 0 6 2 6
r
W
r
W
r
( ) ( -
)
t
12 2 /
6
( ) 1/ 2
W -
W
2 0
2 6 12 2 /
6
1 2 0
s I I
0
0 =
+ +
=
+ +
=
-
=
r
r
W W W
I
c
c
h
i i t
For homo-nuclear hmax = 0.5
For hetro-nuclear hmax = 0.5 (gs/gi)

9. When 1/tc ~ w0 (or tc w0 ~ 1 ) M.W.~ 103
W2 and W0 effect are balanced. h max ~ 0
improvement:
• Change solvent ofr temperature
• Using rotating frame NOE

10. When 1/tc < w0 (or tc w0 >> 1 ) M.W. > 104
W0 dominant , h max = -1
application
Useful technique for assigning NMR spectra of protein

11. Nuclear Overhauser Effect & distance
NOE 1
µ æ 6
t · ÷øö çè
f ( c )
r

12. citraconic acid mesaconic acid