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

QQ

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.