Probing the Structure and Dynamics of Hydrogen Bonds and ... · Probing the Structure and Dynamics...
Transcript of Probing the Structure and Dynamics of Hydrogen Bonds and ... · Probing the Structure and Dynamics...
Probing the Structure and Dynamicsof Hydrogen Bonds and
Aromatic Pi-Pi Interactionsby Solid-State NMR
Steven P. Brown
Department of PhysicsUniversity of Warwick
Solution-State NMR
10 5 015 ppm
Chemical ShiftDifferentiation of Chemicallyor CrystallographicallyDistinct Sites
J CouplingIdentification of Through-BondConnectivities
Solid-State NMR: Anisotropic Interactions
The resonance frequency of a given nucleus within a particular crystallitedepends on the orientation of the crystallite
For a powdered sample, anisotropic broadening is observed
Solid-State NMR: Anisotropic Interactions
Chemical Shift AnisotropyDipolar
CouplingQuadrupolar
Coupling
Electronic Structureand Bonding
Internuclear Proximitiesand Distances
MotionalProcesses
Relative Magnitudes of Solid-State NMR Interactions
Dipolar Couplings
13C-1H = 23 kHz (directly bonded CH pair)
1H-1H = 20 kHz (CH2 group)
13C-13C = 3 kHz (directly bonded CC pair)
Chemical Shift Anisotropy
13C = 9 kHz (carbonyl group, at 500 MHz)
J Couplings
15N-1H = 90 Hz (directly bonded NH pair)
13C-13C = 35 Hz (directly bonded aliphatic CC pair)
Isotropic Chemical Shift Range
1H = 20 ppm = 10 kHz (at 500 MHz)
13C = 200 ppm = 25 kHz (at 500 MHz)
250 200 150 100 050 −50
60 30 0 −30
14 12 10 8 02 −4−26 4
14 12 10 8 02 −4−26 4ppm
High-Resolution Solid-State NMR
L-alanine
13C MAS5 kHz
1H MAS5 kHz
1H MAS30 kHz
1H CRAMPS
�B0
νr
54.7°
Magic-AngleSpinning
Double-Quantum Coherence
An isolatedspin I = 1/2
nucleus
A single resonanceat the Larmor
frequency
Single-Quantumcoherence
m = + 1/2
m = − 1/2
∆m = ±1
ω0
ω0
Double-Quantum (DQ) (∆m = ±2) coherences cannotbe directly observed in an NMR experiment, but they
can be indirectly probed by a 2D experiment
A through-spacedipolar-coupled pair of
spin I = 1/2 nuclei
The observable(SQ) spectrum
(Also applies to a
through-bond
J-coupledspin pair)
ωD
M = + 1
M = − 1
M = 0
ω0 − ωD/2
ω0 + ωD/2
, DQ
SQ
SQ
Excitationof DQC
Evolutionof DQC (t1)
Acquisitionof FID (t2)
Conversionto SQC
A Two-Dimensional Double-Quantum Spectrum
To a first approximation,the signal intensity is
proportional to thedipolar coupling squared
(double-quantumcoherences must be bothexcited and reconverted),
i.e., the signal intensityis inversely proportional
to the internucleardistance to the
sixth power.
Therefore, a DQ peak isonly observed if there isa close proximity of the
involved protons. single-quantum dimension
doub
le-q
uant
um d
imen
sion
A
A A
A B
B B
B
ωA
ωA
ωA
ωB
+ω
Aω
B+
ωB
ωB
+
Recovering the 13C-13C J Coupling
L-alanine
13C
1H
1H1H
1H 13C13C
13C−1HJ coupling
1H−1Hdipolar coupling
13C CSA
13C−1Hdipolar coupling
13C−13Cdipolar coupling
13C−13CJ coupling
13C Chemical Shift / ppm
MAS (30 kHz)1H decoupling
(TPPM)
13C−13CJ coupling
is observed
181920212223 ppm
176177178179180 ppm
CH3
CO
through-bond connectivitesare traced out
α COβ
γ
δ'ε'
ζε
δ
The Solid-State INADEQUATE Experiment
Lesage et al, JACS 119, 7867 (1997)
Fyfe et al, JACS 112, 3264 (1990)
Only homonuclear J couplingsare active during 2τ
Double-Quantum Coherence iscreated for J-coupled nuclei
CP
1H:TPPM
CP
X, e.g.13C15N
t1τ τ
p = 0+1
−1−2
+2
t2
Cα CβCγCδ'
Cδ Cε Cε'Cζ
CO
406080100120140160180
100
140
180
220
260
single quantum frequency (ppm)
doub
le q
uant
um fr
eque
ncy
(ppm
)
Hydrogen-Bond Mediated J-Couplings: Solution-State NMR of Biomacromolecules
Dingley & Grzesiek JACS 120, 8293 (1998)
Watson-Crick Base Pairs
2hJNN = 7-10 Hz 1hJHN = 2-4 Hz
15N H
13C'
residue i residue j
O
13C� H�
13C'O
13C�
15N H
The Secondary Structureof Proteins
3hJNC' = 0-1 Hz
Cordier and Grzesiek,JACS 121, 1601 (1999)
Cornilescu et al,JACS 121, 2949 (1999)
The hydrogen-bond mediated J couplings depend on the hydrogen-bonding distances
and geometries, and are also correlated with the 1H chemical shifts.
Is it Possible to Observe Hydrogen-Bond Mediated J-Couplings in the Solid State?
-60 -100 -140 -180 -220 ppm
15N Chemical Shift / ppm (relative to nitromethane)
N1
N9
N1'N3' N4'
N
N
C6H5
N
H
N
N
1
4'
3'
1'
9
solution (CDCl3)(Claramunt et al
Angew. Chem. 40, 420):
1JNN = 11.8 Hz
2hJNN = 8.6 Hz
The homonuclear
J couplings are
not resolved in the15N CP-MAS spectrum
N3' N4'
N9
N1'
N1
The Spin-Echo Experiment and Refocused Linewidths
The spin-echo experiment
CP τ τ
p = 0
+1
−1
All terms that appear as offsets(due to e.g. a chemical shift
distribution or imperfect decoupling)are refocused (i.e., removed) Refocused linewidths as small
as a few Hz are observed.
Lesage, Bardet, & Emsley,JACS 121, 10987 (1999)
Earl & VanderHartJACS 102, 3251 (1980)
Cowans & GrutznerJMR A105, 10 (1993)
N
N
C6H5
N
H
N
N
1
4'
3'
1'
9
15N INADEQUATE Spectra
15N Single-Quantum Frequency
15N Chemical Shift− 50 ppm200−150−100−
N3'N4' N9 N1'
N1CPMAS
1D INADEQUATE
ppm −100 −150 −200 −250
−260
−300
−380
−340
15N
Dou
ble-
Qua
ntum
Fre
quen
cy
N9
N1'
N1
N9
−100 −200
2D INADEQUATE
Direct Detectionof a Solid-StateHydrogen Bond
Brown et al,JACS 124, 1152
Homonuclear J Spectroscopy
The spin-echo experiment
CP τ τ
p = 0
+1
−1
For a series of rotor-synchronised τ values, measure the integrated
intensity (after Fourier transformation)for a given resonance
S(τ) = A exp(−2τ / T2) cos(2π J τ)
Zero crossings at: 2π J τ = (2n-1) (π/2)
0.0
0.5
1.0
τ
inte
nsity
/ a.
u.
τ
0.0
0.5
−0.5
1.0
inte
nsity
/ a.
u.
S(τ) = A exp(−2τ / T2)
(1/4J) (3/4J) (5/4J)
Kubo & McDowellJCP 92, 7156 (1990)
Wu & WasylichenOrganometallics 11, 3242 (1992)
Homonuclear J Spectroscopy: Measuring Homonuclear J Couplings
one J-coupled neighbour
fit to A exp(−2τ / T2) cos(2π J τ) A exp(−2τ / T2) cos(2π J1τ) cos(2π J2τ)
0 10 20 30 40 50
−0.8
−0.4
0.0
0.4
0.8
τ / ms
inte
nsity
/ a.
u.
N
N
C6H5
N
H
N
N
1
4'
3'
1'
9
T2 = 248 ± 15 msFWHMH = 1.3 Hz
1J(N9,N1') = 11.9 ± 0.1 Hz
0 10 20 30 40 50−0.2
0.0
0.2
0.4
0.6
0.8
1.0
τ / ms
inte
nsity
/ a.
u.
N
N
C6H5
N
H
N
N
1
4'
3'
1'
9
T2 = 194 ± 15 msFWHMH = 1.6 Hz
1J(N9,N1') = 12.0 ± 0.1 Hz
2hJ(N1...H...N9) = 7.2 ± 0.1 Hz
two J-coupled neighbours: fit to
The Determination of 15N-15N J Couplings
Pyrrole derivative in solution (CDCl3): J = 10.3 Hz J = 9.0 Hz
Triazole derivative in solution (CDCl3): J = 11.8 Hz J = 8.6 Hz
0 10 20 30 40 50
−0.8
−0.4
0.0
0.4
0.8
τ / ms
inte
nsity
/ a.
u.
N
N
C6H5
N
H
N
N
1
4'
3'
1'
9
J =11.9 ± 0.1 Hz
J =10.3 ± 0.1 Hz
0 10 20 30 40 50
−0.8
−0.4
0.0
0.4
0.8
τ / ms
inte
nsity
/ a.
u.
N
N
C6H5
N
H
1
1'
9
0 10 20 30 40 50
0.6
0.8
−0.4
−0.2
0.0
0.2
0.4
1.0
τ / ms
inte
nsity
/ a.
u. N
N
C6H5
N
H
1
1'
9
J =8.1 ± 0.2 Hz
0 10 20 30 40 50
0.0
0.2
0.4
0.6
0.8
1.0
τ / ms
inte
nsity
/ a.
u. N
N
C6H5
N
H
1
1'
9
J = 8.0± 0.3 Hz
J = 10.2± 0.4 Hz
0 10 20 30 40 50−0.2
0.0
0.2
0.4
0.6
0.8
1.0
τ / ms
inte
nsity
/ a.
u.
N
N
C6H5
N
H
N
N
1
4'
3'
1'
9
J = 7.2± 0.1 Hz
J = 12.0± 0.1 Hz
0.0
0.5
1.0
0 10 20 30 40 50τ / ms
inte
nsity
/ a.
u.
−0.5
N
N
C6H5
N
H
N
N
1
4'
3'
1'
9
J =7.4 ± 0.1 Hz
1H MAS NMR of an Alkyl-Substituted Hexabenzocoronene Derivative
Hexabenzocoronene(HBC) derivativespossess very high1D charge carriermobilities because
of the overlap of theπ orbitals due to thepolyaromatic cores
A B CC12D2H23
C12D2H23
C12D2H23
C12D2H23
H23D2C12
H23D2C12
HH
HH
HH
HH
HH
HH
MAS at35 kHz
500 MHz(11.8 Tesla)
-4-210121416 8 6 4 2 0 ppm
solid phase(T = 60 °C)
liquid-crystalline
phase(T = 110 °C)
In solution (CDCl3), there is a single aromatic1H resonance with a concentration-dependent
chemical shift between 8.0 and 8.9 ppm
1H DQ MAS NMR of an Alkyl-Substituted Hexabenzocoronene Derivative
�
�
�
�
� � �
C12D2H23
C12D2H23
C12D2H23
C12D2H23
H23D2C12
H23D2C12 �
A B C
single-quantum dimension
doub
le-q
uant
um d
imen
sion
12 10 8 6 4 2 0 -2 ppm
-5
0
5
10
15
20
�C �C
�A �B
MAS at 35 kHz500 MHz (11.8 Tesla)
solid phase (T = 60 °C)
�C �C�A �B
two types of pairs:
and
in a ratio 2:1
The Packing of the Aromatic Cores in Hexabenzocoronene
� �� �
� � � � �
��
�
� �
��
�
��
�
�
� �
AA
A A
CC
C C
BB
B B
Herring-bonearrangement
optimisespi-pi packing
deshielded(high ppm)
shielded(low ppm)
The staggeredarrangement of
the aromatic coresleads to three
different chemicalshifts, becauseof the different
ring currenteffects
DQ MAS Spinning-Sideband Patterns
doub
le-q
uant
um
doub
le-q
uant
um
ppm
8
12
16
20
single-quantum
single-quantum
10 8 6 4ppm
5 0 -5 -10 -15
ω/ωR
1015
D.τexc
2.8
2.4
2.0
1.6
1.2
0.4
0.8
DQ MAS Spinning-Sideband Patterns
ppm
1H DQ MAS spinning-sidebandpatterns are very sensitive to
the dipolar coupling
1 -1 -3 -5 ω/ωR35
fast rotation about columnar axis:reduction of dipolar coupling by 0.5
best-fit simulations:Solid phase: D = 15.0 ± 0.9 kHzLC phase: D = 6.0 ± 0.5 kHz
LC order parameter S = 0.80 ± 0.08
solid phaseMAS at 35 kHzτexc = 57 µs
LC phaseMAS at 10 kHzτexc = 200 µs
1H (700 MHz) NMR of a Molecular Tweezer
ppm
�
��
��
ppm
-3-2-111 10 9 8 7 6 5 4 3 2 1 0 ppm
-6
-4
-2
22
20
18
16
14
12
10
8
6
4
2
0
H1 H2
H1H2
MAS at30 kHz
DQ MAS spectrum
CN
CN
HHHH
-3-2-111 10 9 8 7 6 5 4 3 2 1 0 ppm
single-quantum dimension
doub
le-q
uant
um d
imen
sion
1H-13C (700 MHz) Correlation Spectrum of a Molecular Tweezer
ppm
�
��
��
MAS at30 kHz
CN
CN
HHHH
13C chemical shift1H chemical shift
20406080100120140160180 ppm
-1
10
9
8
7
6
5
4
3
2
1
0
-4-214 12 10 8 6 4 2 0 ppm
1 H c
hem
ical
shi
ft
One-bond (C-H) correlations
Ring Current Effects on the Guest
ppm
�
��
��
CN
CN
HHHH
ViewA
ViewA
ViewB
ViewC
ViewC
ViewB
b
a
b
a
b
a
Ab initio 1H chemical shift calculationsGIAO-HF/TZP//HF/6-31G*
vac- View View View vacuum fulluum A B C −sum calc.
Ha 8.0 −0.9 −0.9 −1.0 5.2 5.3
Hb 7.9 −1.2 −3.6 −1.7 1.4 1.7
(Ochsenfeld et al, Solid State NMR 22, 128, 2002)
Probing the Guest Dynamics
Upon heating, thetwo 1H guest aromaticresonances coalesce
because ofguest dynamics
ppm
-3-2-111 10 9 8 7 6 5 4 3 2 1 0 ppm
-6
-4
-2
22
20
18
16
14
12
10
8
6
4
2
0
H1 H2
H1H2
Temperature-dependent
changes in slicesfrom 1H DQ MAS
spectra
T/K
410
396
381
367
353
-210 8 6 4 2 0 ppm
�
��
��
CN
CN
HHHH
� �� �
�
�
� �
� �
� �� �
�
� �
� �
�
�
� �� �
�
�
�
��
�
� � � �N N N
N
Ha Ha
Ha
Ha
Ha Ha
Hb
Hb
Hb
Hb
Hb
Hb
N N
1H (700 MHz) NMR of Bilirubin
responsible for jaundice in new-born babiesinsoluble in aqueous solution, because ofstrong intramolecular hydrogen bonding
�
�
O
O
H
H HH H
H
C
C
CH2
N N
N N
O
O
O
O
-6-4-220 18 16 14 12 10 8 6 4 2 0 ppm
MASat 30 kHz
DQ MASspectrum
OH NH1
ppm
891011121314151617 ppm
8
10
12
14
16
18
20
22
24
26
28
30
NH2
OH NH1
NH2NH1
1H (700 MHz) DQ MAS Spinning-Sideband Patterns for Bilirubin
�
�
O
O
H
H HH H
H
C
C
CH2
N N
N N
O
O
O
O
MASat 30 kHz
Fitting to the experimentalDQ MAS spinning-sidebandpatterns allows the accurate
determination of
�
� � � � � � � � � � � � ���
� �
1 -1 -3 -5 -7 -9 ω/ωR3579
186 ± 2 pmH H
τexc67 µs
τexc100 µs
τexc133 µs
Acknowledgements
Alexander von Humboldt-Stiftung (January 1998 - December 1999)
Marie Curie Fellowship (HPMFCT-2000-00525) (January 2001 - September 2002)
EPSRC Advanced Research Fellowship (October 2002-)
Hans W. Spiess,
Max-Planck-Institute for Polymer Research, Mainz, Germany (1998-2000)
Lyndon Emsley,
Ecole Normale Superieure de Lyon, France (2001-2002)
Hydrogen-Bond Mediated J couplings:
Rosa Claramunt, Marta Perez-Torralba, Dionisia Sanz (UNED, Madrid, Spain)
Hexabenzocoronenes:
Klaus Muellen, Johann Diedrich Brand, Ingo Schnell (MPI-P, Mainz, Germany)
Molecular Tweezers:
Frank-Gerrit Klaerner, Torsten Schaller, Uta P. Seelbach (Essen, Germany)
Christian Ochsenfeld, Felix Koziol (Tuebingen, Germany)
Bilirubin:
Xiao Xia Zhu (Montreal, Canada)
Papers
Hydrogen-Bond Mediated J couplings:
Brown et al, J. Am. Chem. Soc. 124, 1152 (2002)
Brown et al, Chem. Comm. 1852 (2002)
Hexabenzocoronenes:
Brown et al, J. Am. Chem. Soc. 121, 6712 (1999)
Molecular Tweezers:
Brown et al, Angew. Chem. Int. Ed. 40, 717 (2001)
Ochsenfeld et al, Solid State NMR 22, 128 (2002)
Bilirubin:
Brown et al, J. Am. Chem. Soc. 123, 4275 (2001)
Review:
Brown et al, Chem. Rev. 101, 4125 (2001)