chapter 18 introduction to solid state nmr 18.0 summary of internal interactions in solid state nmr...
Post on 14-Dec-2015
226 Views
Preview:
TRANSCRIPT
Chapter 18 Introduction to Solid State NMR
• 18.0 Summary of internal interactions in solid state NMR
• 18.1 Typical lineshapes for static samples• 18.2 Magic-angle-spinning (MAS)• 18.3 Cross polarization (CP) and CPMAS• 18.4 Homonuclear decoupling pulse sequenc
es• 18.5 Recoupling (CSA and dipolar)• 18.6 Multi-quantum MAS (MQMAS) of qua
drupole spins• 18.7 Applications
• High resolution solid state NMR
• Recoupling (Secoupling)
• Resolution gap between LSNMR and SSNMR: still large but decreasing
• “Solid NMR” in chemistry and condensed matter physics can be very different (the later normally uses conducting samples that contain large Knight shift)
Single Crystal or Polycrystalline (Powder)
Samples
Review of Lecture 9 for the summary of the four major interactions in NMR spectroscopy.
Magic Angle Spinning (MAS)
B0
Θ=54.74°
Coordinate Systems
( , , )MF PAS
( , , )RF
(0, , )RL M rtLF
Coordinate Systems
( , , )( , , ) (11,22,33)MF X Y Z PAS
( , , )( , , )R R RRF X Y Z
(0, , )( , , ) RL M rtL L LLF X Y Z
33
11
22
ZX
Y
Coordinate Systems
Lab Frame(XYZ)
),,(
JQDCTRHk
k
kmmkmk ,,,
2
0,',
( ) ( ), ", ' ', , '
', "
( ) ( ) ( )'", '' '', ' ', , '
', ", '''
( 1) (0, , ) ( , , )
( 1) (0, , ) ( , , ) ( , , )
km k k
k m m m M r m m k mm m k
km k k k
m m M r m m m m k mm m m k
R D t D
or D t D D
Molecular frame (may be a PAS of certain interaction tensor)
( , , )
β 11
22
33
How to calculate a solid NMR spectrum
JQDCTRHk
k
kmmkmk ,,,
2
0,',
( , , , , , )
( , , , , , )
, ,
( ) sin i t i tS d d d e e dt
More generally,
( , , , , , ) ( , , , , , )
, ,
( ) sin [ (0) ]iH t iH t i tS d d d I e e e dt
Sensitivity
• High Fields• Labeled samples• CP• CPMAS
Cross polarization• CPMAS─one of the most imp
ortant solid state NMR techniques.
• CP contact time: several hundred microseconds to tens of milliseconds.
• Purpose: To enhance the sensitivity of the lower γ spins such as carbon-13. maximal enhancement factor: γI/γS
• Other advantages: Shorter recycle delay time
• Distinguish the interconnectivity of nuclear spins such as the protonation of a certain carbon nucleus.
SI ,1,1
1H-13C CPMAS spectrum of (a) mixed lactose, (b) -lactose and (c) anhydrous stable -lactose. The lines marked by asterisks are assigned to the residual amorphous lactose
Sodium silicate glasses
BONBO
Na2Si2O5
Na2Si3O7
Na2Si4O9
600 0 -600 ppm
Static 17O NMR spectra
bridging (BO) andnon-bridging (NBO)oxygens
Structure of glasses (I)
OSi
OO
OSi
O
O O
SiOO
O
Si
Si
Si
O
Si O
O
O
O
OO
OO
O
Na
Na
Na
NaSi
BO
NBO
29Si NMR spectra for sodium silicate glasses
static MASQ4
Q3 + Q2
0 -100 -200 ppm -60 -80 -100
mole %Na2O
34
37
41
Q2
Q3
Structure of glasses (II)
Q4
Q2
Q1Q3
OSi
HOO
OSi
O
O O
SiOHHO
HO
Si
Si
Si
O
SiO
HO
HO
HO
OO
OO
O
1H-29Si CPMAS intensity as a function of contact time
Different sites in a Na2Si4O9 glass with 9.1 wt% H2O
Q2
Q3
Q4
0 20 40contact time (ms)
Ramp CP(Matching Condition Satisfied at High
Speeds)
2
CPCP decouplingdecoupling
11HH
XX
AcquisitionAcquisition
Comparison of standard and ramp-CP
10 11 12 13 14 15 16 17 18 19 pl2 in dB
Carbonyl-signal of glycine (nat. abundance), Carbonyl-signal of glycine (nat. abundance), rotrot = 20 kHz = 20 kHz,,
as function of as function of 11H-power H-power
rectanglerectangle
rampramp
1I 1S Rn ＝
Double-CP
XXAcquisitionAcquisition
2
CP 1CP 1 DecouplingDecoupling
11HH
CP 2CP 2
YY
Avoid CPAvoid CP
H-N-C Double- CPMAS: Spectral Simplification
(A) CP-MAS 13C NMR spectrum and (B) 15N-13C double-CP/MAS NMR data of the [13C6,15N3]-His labeled LH2 complex,measured at 220 K by using a wide-bore 750 NMR spectrometer. Thespinning rate around the magic angle was kept at 12 kHz. Each spectrumrepresents about 156 000 scans collected with an acquisition time of 8ms and a recycle time of 2 s. The spectra are normalized at the α’ peaks.
de Groot et al., JACS 123,4203(2001).
Shielding
B0
Bi
ii
electronic shielding induced magnetic field
Bloc = B0 – Bi = B0 (1 – s)
Shielding Tensor: Decomposed
s
xx
12
(xy yx)12
(xz zx )1
2(xy yx) yy
1
2(yz zy )
1
2(xz zx )
1
2(yz zy) zz
as
1
2(xy yx)
1
2(xz zx )
12
(yx xy) 12
(yz zy)
12
(zx xz)12
(zy yz)
0
Theoretically, CSA tensor contains anti-symmetric components, but the experimental evidence has been rather weak. It remains an interestingtopic in fundamental NMR research.
(Static) Powder Patterns
Powder spectrum
iso , δ,
2 20 0
1( , ) 3cos 1 sin cos 2
2cs iso
C
CH3
CH3
O S O
O
O x
Magic-Angle-Spinning Spectrum
MAS for spin 1/2 nuclei
Total Suppression of Spinning Side Bands (TOSS)
TOSS Example
TOSS Example
Proton NMR spectra of a water and hexadecane mixture in a sample of packed glass beads.
The Quadrupolar Majority
First and Second Order Quadrupolar Hamiltonains
rfQJDCSAB HHHHHHH
ZB SH SH rf 1
)1()0(QQQ HHH
2
(0) 22203
(1) 2 2221 21
2 222 22
22 2
2 2, 2
20 22 2 28 (2 1)
[3 ( 1)]
[(4 8 1)
(2 2 1) ]
( , ,0) ( , , ) , 0, 1, 2
6 6 ,
L
QQ Z
Q QQ Z Z
Q QZ
Q Qj mj R M nm n
m n
e qQQ Q Q QQ QI I
H V S S S
H S S S V V
S S V V
V D t D j
Experimental (A) and simulated (B and C) 2H MAS NMR
spectra (14.1 T) of KD2PO4 using ωr= 7:0 kHz. The
simulated spectrum in (B) employs the optimized 2H quadrupole coupling and CSA parameters listed below whereas the simulation in (C) only considers the quadrupole coupling interaction. The asterisk indicates the isotropic peak.
2H MAS
HZ HZ + HQ HZ + HQ (powder)
Half-Integer Quadrupolar Spins:Central Transtion
(0) 22203
2 2221 21
2 222
(1)
22
[3 ( 1)]
[(4 8 1)
2 2 1) ]
L
Q
Q QZ
Q QZ
Z
Q Z
Q
V S S
S S V V
S S V V
H
S
S
H
A few hundred Hz to several kHz
Satellite Transitions
Static
MAS
(0) 22203
2 2221 21
2 222
(1)
22
[3 ( 1)]
[(4 8 1)
2 2 1) ]L
Q
Q QZ
Q QZ
Z
Q Z
Q
V S S
S S V V
S S V V
H
S
S
H
Hundreds kHz to a few MHz!
23Na ( 105.8 MHz) NMR spectra of NaN03 recorded using (a) static and (b) MAS (v, = 4820 Hz) conditions ( 16 scans). The central transition is cut off at (a) 1/4 and (b) 1/13 of its total height.
Spin-3/2
JORGEN SKIBSTED, NIELS CHR. NIELSEN, HENRIK BILDME, HANS J. JAKOBSEN, JMR, 95, 88(1991)
27AI ( 104.2 1 MHz) MAS NMR spectra of the centra
l and satellite transitions for α-Al2O3. Theppm scale is referenced to an external sample of 1 .0 M AlCl3, in H2O. (a) Experimental spectrum showing the relative intensities of the central and satellite transitions and observed using a Varian VXR-400 S
wideline spectrometer; ωr= 7525 Hz, spectral width
SW = 1 .0 MHz, pulse width pw = 1 .0 μs (π /4 solid pulse), and number of transients nt= 5 12. (b) Spectrum in (a) with the vertical scale expanded by a factor of ten; the inset shows expansion of a region where the second-order quadrupolar shift between th
e (±5/2, ±3/2) and the (±3/2, ±1/2) satellite transitions is clearly observed (see text). (c) Simulated MAS spectrum for the satellite transitions in (b) obtaine
d using QCC = 2.38 MHz, η = 0.00, ωr= 7525 Hz,
and Gaussian linewidths of 900 and I 175 Hz for the (±3/2, ±1/2) and (±5/2, ±3/2) transitions. respectively.
HANS J. JAKOBSEN, JORGEN SKIBSTED, HENRIK BILDSBE, ANDNIELS CHR .NIELSEN,JMR 85,173(1989)
Spin-5/2
51V MAS (HQ+HCSA)
Question: is it possible to suppress the sidebandsof a satellite transition MAS spectrum?“Answer”: Not done yet, but it’s an interesting topic.
Question: is it possible to suppress the sidebandsof a satellite transition MAS spectrum?“Answer”: Not done yet, but it’s an interesting topic.
Direct Dipole-Dipole Coupling
Direct Dipole-Dipole Coupling
Dipolar Coupling
dij 0
4
hij
2 r3
Direct Dipole-Dipole Coupling
Spin Pair
~80 kHz
Many coupled spins
Homogeneous Interaction (Homonuclear Dipolar Interaction): All Spins Are Coupled to Each Other
20
3
,2,0 4
, ,2, 1 2, 2
6
0
i j
ij
D ij
r
D ij D ij
, 12,0 , ,6
, 12, 1 , , , ,2
, 12, 2 , ,2
(3 )
( )
D iji z j z i j
D iji j z i z j
D iji j
T I I
T I I I I
T I I
I I
2(2) , ,
0, 2,0 2,2
( 1) ( , ,0)m D ij D ijD m ij ij m
i j m
H D T
2, ,0
3, ,, 4 | | | |[3( )( ) ]i j i j i j
i j i jijD ij i j i jr
H
r r
r rI I I I
Decoupling Sequences• Hetronuclear decoupling: CW TPPM XiX COMORO SPINAL SDROOPY,eDROOPY,DUMBO, eDUMBO, eDUMBOlk• Homonuclear decoupling WAHUHA Lee-Goldburg (LG and variants: FSLG, PMLG,wPMLG) MREV-8 BR-24 BLEW-12 CORY-24 TREV-8 MSHOT-3 DUMBO, eDUMBO, eDUMBOlk, CNnv, RNnv
Decoupling sequences: TPPM
TPPM = TPPM = TTwo wo PPulse ulse PPhase hase MModulationodulation
0p
p
0p
p
Pulse length: Pulse length: p p - - : : 0 – 0.6 0 – 0.6 s, s, optimize!optimize!
Phaseshift: Phaseshift: , , evt. optimize!evt. optimize!
TPPM- decoupling, optimize tp
optimum pulse length: optimum pulse length: p p = 2.9 = 2.9 s, s,
((s)s)
CC-signal in Glycine-2--signal in Glycine-2-1313C-C-1515N, N, rotrot= 30 kHz, = 30 kHz, = 15° = 15°
2.0 2.5 3.0 3.5 4.0 4.5 p/s
decdec = 150 kHz = 150 kHz
XiX - decoupling
XiX= XiX= XX IInverse nverse XX
Pulse length: Pulse length: p p = = xx · ·RR, , xx n n, but , but xx nn, ... , ...
(recoupling at ((recoupling at (nn/4)/4)RR ) ) optimize!optimize!
0p
180p 0p
180p
nnRR tt
XiX- decoupling, optimize p
CC-signal of glycine-2--signal of glycine-2-1313C-C-1515N, N, rotrot= 30 kHz, = 30 kHz,
9090 9595 100100 105105 110110 115115 pp//ss120120
R4
32 R3
R4
13 R2
13
decdec = 150 kHz = 150 kHz
Comparison of decoupling methods
CC-signal of glycine-2--signal of glycine-2-1313C-C-1515N, N, decdec = 150 kHz = 150 kHz
TPPM (15°) CW XiX
10 kHz
30 kHz
Decoupling methods: π-pulse decoupling
Rotorsynchronised train of 180°-pulsesRotorsynchronised train of 180°-pulsesxy-16-phase cycle for large band widthxy-16-phase cycle for large band width
RR tt
0 90 90 0 0 90 90
xy-16-phase cycle: 0–90–90–0–0–90–90–0–180–270–270–180–xy-16-phase cycle: 0–90–90–0–0–90–90–0–180–270–270–180–180–270–270–180180–270–270–180
π-pulse decoupling for 19F1919F: Dipol-Dipol-coupling spun out at fast rotationF: Dipol-Dipol-coupling spun out at fast rotation but: large chemical shift anisotropybut: large chemical shift anisotropy large band width large band width important important
-2e+044e+04 2e+04 0e+00 Hz
1000 0 Hz
1919F-spectrum ofF-spectrum ofteflon at 30 kHzteflon at 30 kHz
π-pulse-decoupling for 19F
1313C{C{1919F}-CP/MAS-spectrum of Teflon, F}-CP/MAS-spectrum of Teflon, rotrot= 30 kHz= 30 kHz
CWCW TPPM 15°TPPM 15° -pulse-pulse
100120140 ppm 100120140 ppm 100120140 ppm
Pulsed (homonuclear) decoupling
WAHUHA Lee-Goldburg (LG and variants: FSLG, PMLG, w
PMLG) MREV-8 BR-24 BLEW-12 CORY-24 TREV-8 MSHOT-3 DUMBO, eDUMBO, eDUMBOlk, CNnv, RNnv
Lee-Goldburg (LG) Series
LG: Magic-angle-spinning in spin space (Magic Sandwich)
[ ]n
*X
Y
Z 54.74o
ωrf
Δω
[ ]n
* 1 cos( )rf pt
Frequency-Switched LG (windowed) Phase-Modulated LG
TREV-8
[ ]n*
MSHOT (Magic Sandwich High Order Terms Decoupling)
MSHOT
Malonic Acid
M. Hohwy and N. C. Nielsen, J. Chem. Phys. 106, 7571 (1997).M. Hohwy, P. V. Bower, H. J. Jakobsen, and N. C. Nielsen, Chem,Phys. Lett. 273, 297 (1997)M. Hohwy, J. T. Rasmussen, P. V. Bower, H. J. Jakobsen, and N. C. NielsenJ. Magn. Reson. 133,374(1998).
KHSO4Ca(OH)2
MSHOT-3-CRAMPS (combination of rotation and multi-pulse spectroscopy
PMLG, wPMLG
wPMLG: Example
The one-dimensional proton spectra of (a) U–15N–DL-alanine, (b) monoethyl fumarate, (c) glycine and (d) U–13C –15N–histidineHClH2O, detected during wPMLG-5 at a spinning frequency of 14.3 kHz and a Larmor frequency of 300 MHz. The length of the dete
ction windows was 3.2μs and that of the PMLG pulses was 1.7 μs.
2D proton–proton correlation spectra of U–13C–histidineHClH2O, obtained using the pulse sequence shown at the top,with mixing times of (a) 200 μs and (b) 500 μs. The F1 (vertical) and F2 (horizontal) proton spectra are skyline projections of the 2Dspectra. These experiments were performed at a spinning frequency of 14.286 kHz and a Larmor frequency of 300 MHz. During thePMLG-9 and wPMLG-5 irradiation the pulse lengths were 1.1 and 1.7 μs, respectively. The length of the detection windows duringwPMLG-5 was 3.2 μs.
2D carbon–proton correlation spectra of U–13C–histidineHClH2O, obtained using the pulse sequence shown at the top,with Lee–Goldburg CP mixing times of (a) 80 μs and (b) 3 ms. The F1 (vertical) carbon and F2 (horizontal) proton spectra are skyline projections of the 2D spectra. These experiments were performed at a spinning frequency of 14.286 kHz and a Larmor frequency of 300 MHz. During the wPMLG-5 irradiation the pulse lengths were 1.7 μs and the length of the detection windows was 5.1 μs.
FSLG for Heteronuclear Decoupling
CHCH2
Pulsed (homonuclear) decoupling (WAHUHA (WHH4), MREV-8)
P. MANSFIELD, M. J. ORCHARD, D. C. STALKER, AND K. H. B. RICHARDS, Phys. Rev. B 7, 90 (1973).W. K. RHIM, D. D. ELLEMAN, AND R. W. VAUGHAN, .I. Chem. Phys. 59, 3740 (1973).W. K. RHIM, D. D. ELLEMAN, L. B. SCHREIBER, AND R. W. VAUGHAN, J. Chem. Phys. 60, 4595 ( 1974).
J. S. WAUGH, L. HUBER, AND U. HAEBERLEN, Phys. Rev. Lett. 20, 180 (1968).
[ ]n
*
BR-(24,48,52)
D. P. BURUM AND W. K. RHIM, J. Chem. Phys. 71, 944 (1979).
[ ]n*
BLEW-(12,48)
D. P. BURUM,* M. LINDER, AND R. R. ERNST, J. MAGN. RESON. 4, 173-188 (1981)
[ ]n*
CORY-24
[ ]n*
eDUMBO (experimental Decoupling Using Mind-Boggling Optimization)
Hrf =ω1[Ixcosψ(t)+Iysinψ(t)]
MAS rate = 22 kHz
DUMBO and eDUMBO
Flow diagrams illustrating (a) the DUMBO and (b) the eDUMBO approaches to developing improved decoupling schemes.
Symmetry Based Decoupling Pulse Sequences
[ ]n
*
Indirect Spin-Spin Coupling
•
Dipolar-Chemical Shift NMR (1D)
• The interplay of chemical shift anisotropy and spin-spin coupling interactions results in complex line shapes.
• The dipolar-chemical shift method is useful in the case of isolated spin pairs.
Many other cases where more than one interaction are involved.
Multidimensional Approaches
• Separation of Local Fields (Correlation)
• MQC-SQC Correlation
Separation of Local Fields
Chemical shift correlation
Chemical shift -dipolar correlation
Chemical shift-quadrupolar correlation
t1 tm t2I
S
Interaction A Interactions B(+A)Mixing
Homonuclear correlation : establishing connectivities
Dipolar - Chemical Shift Correlation
Dipolar Coupling
dij 0
4
hij
2 r3
Measuring dipolar coupling constants
Homonuclear correlation between I = 1/2 spins
Double/single quantum correlation
Homonuclear double/single-quantum correlation
C
OH
O
O
HO
C C
H
H
C
OH
O
MQMAS
rfQJDCSAB HHHHHHH
ZB SH SH rf 1
)1()0(QQQ HHH
QQQQ
IIqQe
QnnmMRmj
nm
Qj
QQZ
QQZZQ
ZQ
Q
jDtDV
VVSS
VVSSSH
SSSVH
L
2222)12(820
222
2
2,2
222222
2121222)1(
2203
2)0(
,66
2,1,0,),,()0,,(
])122
)184[(
)]1(3[
2
Under rapid magic angle spinning (MAS):
)](cos)(),(
)(cos)(),()([
444
22200
2
MS
MSS
II
PICA
PICAICAL
Q
Lineshape of half-integer quadropolar nuclei
static MAS
Dig EFGs From Dig EFGs From This Spectrum!This Spectrum!
Energy Levels of a Spin-3/2 Nucleus in a Static Magnetic Filed
m3/2
1/2
-1/2
-3/2
Zeeman
Quadrupolar (first-order)
Quadrupolar (second-order)
Quadrupolar Coupling May Be Very Strong!
Multiple Multiple SitesSites
In A PowderIn A Powder
)](cos)(),(
)(cos)(),()([
444
22200
2
PICA
PICAICAS
SSII L
Q
)](cos)(),(
)(cos)(),()([
444
22200
2
PICA
PICAICAS
SSII L
Q
Both The EFG Information And High Resolution Can Be Achieved.
Second Order Quadrupolar FrequencySecond Order Quadrupolar Frequency Second Order Quadrupolar FrequencySecond Order Quadrupolar Frequency
2D Solution:Keep AND Remove2D Solution:Keep AND Remove2D Solution:Keep AND Remove2D Solution:Keep AND Remove0)74.54(cos2 oP 0)74.54(cos2 oP
]0,0[])(cos)()(cos)(
,)(cos)()(cos)([
24241414
22221212
tPICtPIC
tPICtPIC
MS
MS
MS
MS
)()(/ 142421 ICICtt SS )()(/ 142421 ICICtt SS
θM θM
MQC SQC Magic AngleMagic Angle
(54.7 ) (54.7 ) SpinningSpinning
oo
Multi-Quantum Magic-Angle Spinning (MQMAS)
Multiple quantum selection : phase cycles
(i) direct method(ii) indirect method
L.Frydman, J.S.Harwood, JACS, 1995.L.Frydman, J.S.Harwood, JACS, 1995.
17O-MQMAS spectrum of the silicate coesite
MQMAS Signal Enhancement
RIACTQCPMGShaped PulsesFASTERSPAM + STMAS…
What MQMAS Tells And Does Not What MQMAS Tells And Does Not TellTell
Three Principal Values—Yes! Plus Isotropic Chemical ShiftThree Principal Values—Yes! Plus Isotropic Chemical Shift
VV3333VV2222
VV1111
XX
YY
ZZ
Orientation—No For Powder Samples UsedOrientation—No For Powder Samples Used
The The Relative OrientationRelative Orientation Between Two QuadBetween Two Quadrupolar Tensorsrupolar Tensors
What MQMAS May Tell
VV33,B33,B
YYBB
VV33,A33,A
VV11,A11,A
XXAA
YYAA
VV11,B11,B
VV22,A22,A
VV22,B22,B
XXB B
ZZAAZZBB
Relative Orientation Is The Same For Relative Orientation Is The Same For All Crystallites In A Powder SampleAll Crystallites In A Powder Sample
EFG Tensor of Spin AEFG Tensor of Spin A
EFG Tensor of Spin BEFG Tensor of Spin B
MQMAS Spin Diffusion/Exchange Pulse MQMAS Spin Diffusion/Exchange Pulse SequenceSequence
PP1 1 tt11 P P22 ttmm P P33 tt22
MQC of Spin A(B)MQC of Spin A(B) SQC of Spin B(A)SQC of Spin B(A)
A(3/2,-3/2)A(3/2,-3/2)B(1/2,-1/2) B(1/2,-1/2) SchemeScheme
Two Spin-3/2 MQMAS-Spin Diffusion Spectrum
MQMAS PeaksCross PeaksCross Peaks
(3/2,-3/2)(3/2,-3/2)(1/2,-1/2)(1/2,-1/2)(3/2,-3/2)(3/2,-3/2)(1/2,-1/2)(1/2,-1/2)
)45,0,90(),,(
.1.0,4.1
,5.0,5.2
0
22,
11,
oo
q
q
MHzC
MHzC
)45,0,90(),,(
.1.0,4.1
,5.0,5.2
0
22,
11,
oo
q
q
MHzC
MHzC
Ding Lab
Ding Lab
3D CSA-D Correlation (with One Quadrupolar Spin)
J. Grinshtein, C. V. Grant, L. Frydman,J Am Chem Soc 124,13344(2002).
Six nonequivalent Na sites are resolved.
Recoupling
• High resolution achieved with MAS sacrifices information on anisotropy.
• Anisotropy can be recovered with recoupling
• Selective and broadband recoupling
• CSA recoupling and dipolar recoupling
CSA Recoupling
• Off magic angle spinning
• Stop and go (STAG)
• Magic-angle-hopping (MAH)
• Switching-angle-spinning (SAS) or Dynamic-angle-spinning (DAS)
• Magic-angle-turning (MAT)
• (SPEED)
Dipolar Recoupling
• SEDOR
• REDOR
• DRAMA
• (DRAW)
• TRAPDOR
• REAPDOR
• C7
Dipolar recovery at the magic angle (DRAMA)
Full DRAMA sequence
Zero and double quantum coherence
Double quantum filtered experiments
The C7 recoupling sequence
Rotational resonance experiment
Data resulting from rotational resonance
Heteronuclear correlation : general spin-echo sequence
Spin-echo double resonance experiment (SEDOR)
The REDOR experiment
Transfer of population in double resonance (TRAPDOR )
Adiabatic zero crossing
1
2
R
REAPDOR sequence for measuring dipolar couplings between I ≥ 1 and I = 1/2 spins
Example of relaxation: dipolar relaxation
How does the magnetization relax back to equilibrium after applying a radiofrequency pulse?
How does the spectra density J depend on the correlation time?
•
In the extreme narrowing limit (very fast motion and very short correlation time), the following holds.
•
Other Topics
• Multiple pulse for homonuclear decoupling (WAHUHA, MREV, HR, CORY etc)
• Combination of rotation and multiple pulses (CRAMP)
• Recoupling (Rotational Resonance, REDOR, RFDR etc)
• Other multi-dimensional solid state NMR (HETCOR, CSA/Q correlation, D/Q correlation, 3D correlation spectra)
• Single-Crystal NMR
Applications
• Polymers
• Glasses
• Porous materials
• Liquid crystals
Schematic of a typical semicrystalline linear polymer
Stereochemical issue in substituted polymers
H H
linear polyethylene
isotactic polypropylene
syndiotactic polypropylene
atactic polypropylene
Signature of stereoregularity in the solid state spectrum
Static 2D exchange spectrum for polyethyleneoxide (PEO)
Experiment Simulation
3D static 13C exchange spectra of polyethyleneoxide polyvinylacetate
Applications
• Polymers
• Glasses
• Porous materials
• Liquid crystals
Static whole-echo 207Pb NMR spectrain Pb-silicate glasses
mol %PbO6650.531
4000 0 -4000 ppm
Linewidth ~400 kHz @ 9.4 T—> signals of 6 experiments summed up
Sodium silicate glasses
BONBO
Na2Si2O5
Na2Si3O7
Na2Si4O9
600 0 -600 ppm
Static 17O NMR spectra
bridging (BO) andnon-bridging (NBO)oxygens
Structure of glasses (I)
OSi
OO
OSi
O
O O
SiOO
O
Si
Si
Si
O
Si O
O
O
O
OO
OO
O
Na
Na
Na
NaSi
BO
NBO
29Si NMR spectra for sodium silicate glasses
static MASQ4
Q3 + Q2
0 -100 -200 ppm -60 -80 -100
mole %Na2O
34
37
41
Q2
Q3
Structure of glasses (II)
Q4
Q2
Q1Q3
OSi
HOO
OSi
O
O O
SiOHHO
HO
Si
Si
Si
O
SiO
HO
HO
HO
OO
OO
O
1H-29Si CPMAS intensity as a function of contact time
Different sites in a Na2Si4O9 glass with 9.1 wt% H2O
Q2
Q3
Q4
0 20 40contact time (ms)
Efficiency for (1H 29Si)-CP
2
CPCP decouplingdecoupling
11HH
29Si
AcquisitionAcquisition
29Si MAS NMR spectra for a CaSi2O5 glass
x 8
glass
crystal
SiO4 SiO5 SiO6
-50 -100 -150 -200 ppm
quenched from a10 GPa pressure meltisotopically enriched
high pressure phasenormal isotopes
11B MAS NMR spectra for a sodium borate glass
30 15 0 ppm
data
fit
data
fit
R BO4
BO4
NR
NR
R
slow cooled
fast cooled
(with 5 mole% Na2O)
31P MAS NMR spectra for sodium phosphate glasses
mol % Na2O
56
53
40
30
15
5
100 0 -100 ppm
Q1 Q2
Q3
31P double-quantum NMR spectrum
Dou
ble-
quan
tum
dim
ensi
on (
ppm
)
0
-60
0 -30Single-quantum dimension
1-1
1-2
2-1
2-2
Q1 Q2
1H MAS NMR spectrum for a GeO2-doped silica glass
loaded with H2 and UV-irradiatedafter subtractionof intense back-ground signal
GeH
SiOH + GeOH
12 6 0 -6 ppm
Sample contains ~8 1019 H atoms/cm3
(corresponding to about 500 ppm of H2O)
9.4 T, 10 kHz spinning
17O 3QMAS NMR spectrum for a glass on the NaAlO2-SiO2 join with Si/Al = 0.7
MA
S d
imen
sion
(pp
m)
Isotropic dimension (ppm)
-50
0
50
100
0 -10 -20 -30 -40 -50
Al-O-Al
Si-O-Al
17O 3QMAS NMR spectrum for a borosilicate
Si-O-Si
Si-O-B
B-O-B
MA
S d
imen
sion
(pp
m)
Isotropic dimension (ppm)-25 -50 -75 -100
-100
-50
0
50
100
11B-{27Al} CP-HETCOR NMR spectrum
BO4BO3
AlO6
AlO4
AlO5
40 20 0 -20 ppm
-80
0
80
Applications
• Polymers
• Glasses
• Porous materials
• Liquid crystals
Porous materials
Sodalite Zeolite A
Porous materials
Faujasite Cancrinite
Porous materials
Zeolite ZK-5 Zeolite Rho
Zeolite framework projections
AlPO4-5along [001]
AlPO4-11along [100]
VPI-5along [001]
High-resolution 29Si MASNMR spectra of syntheticNa-X and Na-Y zeolites
-80 -90 -100 -110 -80 -90 -100 -110
(Si/Al) = 1.03
1.19
1.35
1.59
1.67
1.87
2.00
2.35
2.56
2.61
2.75
43
21 0
4
32
10
n =Si(nAl) lines
Possible ordering schemes for zeolite Y
Si/Al = 1.67
Si
Al
Intensity ratios:Si(4Al):Si(3Al):Si(2Al):Si(1Al):Si(0Al)
29Si MAS NMR spectrum of highly siliceous mordenite
-110 -112 -114 -116 -118 ppm
21
3
Intensities
Mordenite structure along [001]
T-site No. per unit cell Neighbouring sites Mean T-O-T bond angle
T1 16 T1, T1, T2, T3 150.4°T2 16 T1, T2, T2, T4 158.1°T3 8 T1, T1, T3, T4 153.9°T4 8 T2, T2, T3, T4 152.3°
Mordenite structure along [001]
T-site No. per unit cell Neighbouring sites Mean T-O-T bond angle
T1 16 T1, T1, T2, T3 150.4°T2 16 T1, T2, T2, T4 158.1°T3 8 T1, T1, T3, T4 153.9°T4 8 T2, T2, T3, T4 152.3°
T1/T3/T2+T4 : 3 cross peaksT1/T4/T2+T3 : 2 cross peaksT2/T3/T1+T4 : 2 cross peaksT2/T4/T1+T3 : 3 cross peaks
29Si MAS NMR spectrum of highly siliceous mordenite
J-scaled COSY spectrum
-110 -112 -114 -116 -118 ppm
T1
T3
T2 + T4
T1/T3/T2+T4 : 3 cross peaksT1/T4/T2+T3 : 2 cross peaksT2/T3/T1+T4 : 2 cross peaksT2/T4/T1+T3 : 3 cross peaks
29Si MAS NMR spectra of ultrastabilized and hydrothermally realuminated zeolites
3
21
0Si/Al = 2.56
4.96 4.26 7.98
2.44 2.70 2.09
-80 -90 -100 -110 -120 -90 -100 -110 -120 -90 -100 -110 ppm
Chemical reactions in zeolites
{C} + H2O CO + H2 (water gas reaction)1000 °C
Chemical reactions in zeolites
{C} + H2O CO + H2 (water gas reaction)
……. + x O2 (n-x) CO + n H2 + x CO2 (water gas shift)
1000 °C
Chemical reactions in zeolites
{C} + H2O CO + H2 (water gas reaction)
……. + x O2 (n-x) CO + n H2 + x CO2 (water gas shift)
CO + 2 H2 CH3OH (conversion of synthesis gas)
1000 °C
catalyst
Chemical reactions in zeolites
{C} + H2O CO + H2 (water gas reaction)
……. + x O2 (n-x) CO + n H2 + x CO2 (water gas shift)
CO + 2 H2 CH3OH (conversion of synthesis gas)
CH3OH CH3OH + CH3OCH3
1000 °C
catalyst
Zeolites
150 °C
Chemical reactions in zeolites
{C} + H2O CO + H2 (water gas reaction)
……. + x O2 (n-x) CO + n H2 + x CO2 (water gas shift)
CO + 2 H2 CH3OH (conversion of synthesis gas)
CH3OH CH3OH + CH3OCH3
…….. complex mixture of hydrocarbons
1000 °C
catalyst
Zeolites
150 °C
Zeolites
300 °C
Chemical reactions in zeolites
{C} + H2O CO + H2 (water gas reaction)
……. + x O2 (n-x) CO + n H2 + x CO2 (water gas shift)
CO + 2 H2 CH3OH (conversion of synthesis gas)
CH3OH CH3OH + CH3OCH3
…….. complex mixture of hydrocarbons
1000 °C
catalyst
Zeolites
150 °C
Zeolites
300 °C
13C MAS NMR spectrum of H-ZSM-5 with 50 torr of adsorbed MeOH heated to 300 °C for 35
mins
40 30 20 10 0 -10 ppm
0 -5 -10 -15
13C MAS NMR spectrum of H-ZSM-5 with 50 torr of adsorbed MeOH heated to 300 °C for 35
mins
40 30 20 10 0 -10 ppm
0 -5 -10 -15 C H
scalar coupling
1JCH = 125 Hz
a quintet with ratio 1:4:6:4:1 is expected for methane
Heteronuclear 2D J-resolved 13C MAS NMR spectrum
26 24 22 18 17 16 15 -11 -12 ppm
300
200
100
0 Hz
-100
-200
-300
13C NMR spin diffusion spectrum of products of methanol conversion over zeolite ZSM-5
25 20 15 10 ppm
13C MAS NMR spectrum of H-ZSM-5 with 50 torr of adsorbed MeOH heated to 300 °C for 35
mins
40 30 20 10 0 -10 ppm
0 -5 -10 -15
Methane
Ethane
Propane
Cyclopropane
n-Butane
Isobutane
(n-Pentane)
Isopentane
n-Hexane
n-Heptane
Methylated aromatic products
190 185 180 140 135 130 125 ppm
CO
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
H3C
CH3CH3
CH3
CH3
CH3
CH3
H3C CH3
CH3
CH3H3C
CH3
CH3
CH3
CH3
CH3
CH3
CH3
*
* * * *
129Xe NMR as a sensitive tool for materials
0 S Xe Xe Xe E M
0: referenceS: surface collisionsXe: Xe-Xe collisionsE: electric field effectM: paramagnetic species
129Xe as a sensitive probe for various zeolites
Xe
atom
s /g
1020
1021
60 80 100 120 140 ppm
omega
NaY
ZK4
K - L
ZSM-11
ZSM-5
Applications
• Polymers
• Glasses
• Porous materials
• Liquid crystals
Graphitic nanowires
Hexa-peri-hexabenzocoronene (HBC)
HBC monolayer on HOPG
Phase transitions of alkyl substituted HBC
Temperature dependence of the one dimensional charge carrier mobility
Liquid crystalline (dichotic) behaviour ofalkyl substituted HBC‘s
R = C12H25
Hexadodecyl-hexa-peri-hexabenzocoronene (HBC-C12)
Charge carrier mobility in HHTT S
S
S
S
S
S
1H DQ MAS NMR spectra of HBC-C12
-deuterated fully protonated
CD2
CD2
CD2
D2C
D2C
D2C
HH H
H
H
H
HH
HH
H
H
HH
0.180 nm
0.196 nm
Proposed stacking model based on solid state NMR
HH H
H
H
H
HHH
H
H
H
„Graphitic“ stacking
HH H
H
H
H
HHH
H
H
H
Spinning side band simulation in the DQ time domain
For an isolated spin pair, using N cycles of the recoupling sequence for both the excitation and reconversion of DQCs, the DQ time domain signal is given by:
S(t1, t2 0) sin
3
2Dsin 2 cos Rt1 NR
sin3
2Dsin 2 cos N R
D 0hH
2
82r 3with
Ref.: Graf et al. J. Chem. Phys. 1997, 106, 885
and are Euler angles relating the PAF of the diploar coupling tensor to the rotor fixed reference frame
-> distance information in a rigid system, or indication of mobility:
f 1 3cos2
2
Homonuclear correlation between I = 1/2 spins
aromatic protons at 8.3 ppm(crystalline phase)
aromatic protons at 6.2 ppm (LC phase)
aliphatic protons at 1.2 ppm(crystalline phase)
fitted dipolar coupling constants
DQ spinning side band patterns
R = 35 kHz
R = 10 kHz
R = 35 kHz
Effect of additional phenyl spacers
R = -C12H25 or -C6H4-C12H25
R
R
R
R
R
R
Space filling model for HBC-PhC1
X-ray diffraction patterns of the mesophases
•Let us have a tour of solid state NMR following Professor Malcolm H. Levitt.
top related