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 sequences 18.5 Recoupling (CSA and dipolar) 18.6 Multi-quantum MAS (MQMAS) of quadrupole 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) Θ=54.74° B0

Coordinate Systems

Coordinate Systems 33 11 22 Z X Y

Coordinate Systems Lab Frame(XYZ) Molecular frame (may be a PAS of 11 22 33 β Molecular frame (may be a PAS of certain interaction tensor) Lab Frame(XYZ)

How to calculate a solid NMR spectrum More generally,

Sensitivity High Fields Labeled samples CP CPMAS

Cross polarization CPMAS─one of the most important 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.

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 Static 17O NMR spectra bridging (BO) and non-bridging (NBO) oxygens Na2Si2O5 Na2Si3O7 Na2Si4O9 NBO BO 600 0 -600 ppm

Structure of glasses (I) NBO BO

29Si NMR spectra for sodium silicate glasses static MAS Q4 mole % Na2O 34 37 41 Q3 Q2 Q3 + Q2 0 -100 -200 ppm -60 -80 -100

Structure of glasses (II) Q4 Q2 Q3 Q1

1H-29Si CPMAS intensity as a function of contact time Q2 Q3 Q4 Different sites in a Na2Si4O9 glass with 9.1 wt% H2O 0 20 40 contact time (ms)

Ramp CP (Matching Condition Satisfied at High Speeds) Acquisition X CP decoupling 1H

Comparison of standard and ramp-CP Carbonyl-signal of glycine (nat. abundance), nrot = 20 kHz, as function of 1H-power rectangle 10 11 12 13 14 15 16 17 18 19 pl2 in dB ramp

Double-CP CP 1 Decoupling Avoid CP 1H CP 2 Y Acquisition X

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. The spinning rate around the magic angle was kept at 12 kHz. Each spectrum represents about 156 000 scans collected with an acquisition time of 8 ms and a recycle time of 2 s. The spectra are normalized at the α’ peaks. de Groot et al., JACS 123,4203(2001).

Shielding Bloc = B0 – Bi = B0 (1 – s) electronic shielding induced magnetic field Bloc = B0 – Bi = B0 (1 – s)

Shielding Tensor: Decomposed = xx 1 2 ( xy + yx ) xz zx yy yz zy zz æ è ç ö ø ÷ as - | Theoretically, CSA tensor contains anti-symmetric components, but the experimental evidence has been rather weak. It remains an interesting topic in fundamental NMR research.

(Static) Powder Patterns

Powder spectrum iso , δ,

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

2H MAS HZ HZ + HQ HZ + HQ (powder) 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.

Half-Integer Quadrupolar Spins: Central Transtion A few hundred Hz to several kHz

Satellite Transitions Static MAS Hundreds kHz to a few MHz!

Spin-3/2 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.

JORGEN SKIBSTED, NIELS CHR. NIELSEN, HENRIK BILDME, HANS J JORGEN SKIBSTED, NIELS CHR. NIELSEN, HENRIK BILDME, HANS J. JAKOBSEN, JMR, 95, 88(1991)

Spin-5/2 27AI ( 104.2 1 MHz) MAS NMR spectra of the central and satellite transitions for α-Al2O3. The ppm 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 the (±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) obtained 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)

51V MAS (HQ+HCSA) Question: is it possible to suppress the sidebands of 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

Direct Dipole-Dipole Coupling ~80 kHz Many coupled spins Spin Pair

Homogeneous Interaction (Homonuclear Dipolar Interaction): All Spins Are Coupled to Each Other

Decoupling Sequences Hetronuclear decoupling: Homonuclear 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 = Two Pulse Phase Modulation Pulse length: tp  tp - e: e  0 – 0.6 ms, optimize! Phaseshift:   15°, evt. optimize!

TPPM- decoupling, optimize tp Ca-signal in Glycine-2-13C-15N, nrot= 30 kHz,  = 15° 2.0 2.5 3.0 3.5 4.0 4.5 tp/ms ndec = 150 kHz optimum pulse length: tp = 2.9 ms, (tp = 3.2 ms)

XiX - decoupling XiX= X Inverse X ntR t Pulse length: tp = x ·tR, x  n, but x  n, ... (recoupling at (n/4)tR ) optimize!

XiX- decoupling, optimize tp Ca-signal of glycine-2-13C-15N, nrot= 30 kHz, 90 95 100 105 110 115 tp/ms 120 ndec = 150 kHz

Comparison of decoupling methods Ca-signal of glycine-2-13C-15N, ndec = 150 kHz 10 kHz TPPM (15°) CW XiX 30 kHz

Decoupling methods: π-pulse decoupling Rotorsynchronised train of 180°-pulses xy-16-phase cycle for large band width tR t xy-16-phase cycle: 0–90–90–0–0–90–90–0–180–270–270–180–180–270–270–180

π-pulse decoupling for 19F 19F: Dipol-Dipol-coupling spun out at fast rotation but: large chemical shift anisotropy  large band width important -2e+04 4e+04 2e+04 0e+00 Hz 1000 19F-spectrum of teflon at 30 kHz

π-pulse-decoupling for 19F 13C{19F}-CP/MAS-spectrum of Teflon, nrot= 30 kHz 100 120 140 ppm CW TPPM 15° p-pulse

Pulsed (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

Lee-Goldburg (LG) Series LG: Magic-angle-spinning in spin space (Magic Sandwich) X Y Z 54.74o ωrf Δω [ ] n * [ ] * n Frequency-Switched LG (windowed) Phase-Modulated LG

TREV-8 [ ] n *

MSHOT (Magic Sandwich High Order Terms Decoupling)

MSHOT Ca(OH)2 Malonic Acid KHSO4 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. Nielsen J. Magn. Reson. 133,374(1998). Ca(OH)2 Malonic Acid KHSO4

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 detection 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 2D spectra. These experiments were performed at a spinning frequency of 14.286 kHz and a Larmor frequency of 300 MHz. During the PMLG-9 and wPMLG-5 irradiation the pulse lengths were 1.1 and 1.7 μs, respectively. The length of the detection windows during wPMLG-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 CH2 CH

Pulsed (homonuclear) decoupling (WAHUHA (WHH4), MREV-8) [ ] n * J. S. WAUGH, L. HUBER, AND U. HAEBERLEN, Phys. Rev. Lett. 20, 180 (1968). 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).

BR-(24,48,52) [ ] n * D. P. BURUM AND W. K. RHIM, J. Chem. Phys. 71, 944 (1979).

BLEW-(12,48) [ ] n * D. P. BURUM,* M. LINDER, AND R. R. ERNST, J. MAGN. RESON. 4, 173-188 (1981)

CORY-24 [ ] n *

Hrf =ω1[Ixcosψ(t)+Iysinψ(t)] 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 Interaction A Interactions B(+A) Mixing I t1 t2 tm S

Homonuclear correlation : establishing connectivities

Dipolar - Chemical Shift Correlation

Dipolar Coupling

Measuring dipolar coupling constants

Homonuclear correlation between I = 1/2 spins

Double/single quantum correlation

Homonuclear double/single-quantum correlation

MQMAS

Under rapid magic angle spinning (MAS):

Lineshape of half-integer quadropolar nuclei static MAS

Dig EFGs From This Spectrum! Multiple Sites Quadrupolar Coupling May Be Very Strong! Dig EFGs From This Spectrum! m 3/2 1/2 -1/2 -3/2 In A Powder Zeeman Quadrupolar (first-order) Quadrupolar (second-order) Energy Levels of a Spin-3/2 Nucleus in a Static Magnetic Filed

Second Order Quadrupolar Frequency 2D Solution:Keep AND Remove Both The EFG Information And High Resolution Can Be Achieved.

Magic Angle (54.7 ) Spinning Multi-Quantum Magic-Angle Spinning (MQMAS)            Magic Angle (54.7 ) Spinning MQC SQC o θM θM

Multiple quantum selection : phase cycles (i) direct method (ii) indirect method

L.Frydman, J.S.Harwood, JACS, 1995.

17O-MQMAS spectrum of the silicate coesite

MQMAS Signal Enhancement RIACT QCPMG Shaped Pulses FASTER SPAM + STMAS …

What MQMAS Tells And Does Not Tell Three Principal Values—Yes! Plus Isotropic Chemical Shift Z Orientation—No For Powder Samples Used V11 V33 V22 Y X

What MQMAS May Tell The Relative Orientation Between Two Quadrupolar Tensors ZA V33,A ZB V11,B V11,A YA V33,B V22,A V22,B YB XA XB

Relative Orientation Is The Same For All Crystallites In A Powder Sample EFG Tensor of Spin A EFG Tensor of Spin B

MQMAS Spin Diffusion/Exchange Pulse Sequence P1 t1 P2 tm P3 t2 SQC of Spin B(A) MQC of Spin A(B) A(3/2,-3/2)B(1/2,-1/2) Scheme

Two Spin-3/2 MQMAS-Spin Diffusion Spectrum (3/2,-3/2)(1/2,-1/2) Ding Lab MQMAS Peaks Cross Peaks

Ding Lab

3D CSA-D Correlation (with One Quadrupolar Spin) Six nonequivalent Na sites are resolved. J. Grinshtein, C. V. Grant, L. Frydman, J Am Chem Soc 124,13344(2002).

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

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

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 spectra in Pb-silicate glasses mol % PbO 66 50.5 31 Linewidth ~400 kHz @ 9.4 T —> signals of 6 experiments summed up 4000 0 -4000 ppm

Sodium silicate glasses Static 17O NMR spectra bridging (BO) and non-bridging (NBO) oxygens Na2Si2O5 Na2Si3O7 Na2Si4O9 NBO BO 600 0 -600 ppm

Structure of glasses (I) NBO BO

29Si NMR spectra for sodium silicate glasses static MAS Q4 mole % Na2O 34 37 41 Q3 Q2 Q3 + Q2 0 -100 -200 ppm -60 -80 -100

Structure of glasses (II) Q4 Q2 Q3 Q1

1H-29Si CPMAS intensity as a function of contact time Q2 Q3 Q4 Different sites in a Na2Si4O9 glass with 9.1 wt% H2O 0 20 40 contact time (ms)

Efficiency for (1H 29Si)-CP Acquisition 29Si CP decoupling 1H t

29Si MAS NMR spectra for a CaSi2O5 glass SiO4 SiO5 SiO6 x 8 glass crystal quenched from a 10 GPa pressure melt isotopically enriched high pressure phase normal isotopes -50 -100 -150 -200 ppm

11B MAS NMR spectra for a sodium borate glass (with 5 mole% Na2O) data fit slow cooled fast cooled R BO4 NR 30 15 0 ppm data fit R BO4 NR

31P MAS NMR spectra for sodium phosphate glasses mol % Na2O 56 53 40 30 15 5 Q1 Q2 Q3 100 0 -100 ppm

31P double-quantum NMR spectrum -60 2-2 Double-quantum dimension (ppm) 1-2 2-1 1-1 0 -30 Single-quantum dimension

1H MAS NMR spectrum for a GeO2-doped silica glass loaded with H2 and UV-irradiated after subtraction of intense back- ground signal SiOH + GeOH GeH 9.4 T, 10 kHz spinning 12 6 0 -6 ppm Sample contains ~8 ´1019 H atoms/cm3 (corresponding to about 500 ppm of H2O)

17O 3QMAS NMR spectrum for a glass on the NaAlO2-SiO2 join with Si/Al = 0.7 -50 50 100 MAS dimension (ppm) Al-O-Al Si-O-Al 0 -10 -20 -30 -40 -50 Isotropic dimension (ppm)

17O 3QMAS NMR spectrum for a borosilicate -100 -50 50 100 B-O-B MAS dimension (ppm) Si-O-Si Si-O-B -25 -50 -75 -100 Isotropic dimension (ppm)

11B-{27Al} CP-HETCOR NMR spectrum BO4 BO3 -80 80 AlO6 AlO5 AlO4 40 20 0 -20 ppm

Applications Polymers Glasses Porous materials Liquid crystals

Porous materials Zeolite A Sodalite

Porous materials Faujasite Cancrinite

Porous materials Zeolite ZK-5 Zeolite Rho

Zeolite framework projections AlPO4-5 along [001] AlPO4-11 along [100] VPI-5 along [001]

2 High-resolution 29Si MAS NMR spectra of synthetic Na-X and Na-Y zeolites (Si/Al) = 1.03 1.19 1.35 1.59 1.67 1.87 3 2.00 2.35 2.56 2.61 2.75 1 4 4 Si(nAl) lines n = 3 2 1 -80 -90 -100 -110 -80 -90 -100 -110

Possible ordering schemes for zeolite Y Si/Al = 1.67 Intensity ratios: Si(4Al):Si(3Al):Si(2Al):Si(1Al):Si(0Al) Si Al

29Si MAS NMR spectrum of highly siliceous mordenite 3 2 29Si MAS NMR spectrum of highly siliceous mordenite 1 Intensities -110 -112 -114 -116 -118 ppm

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] T1/T3/T2+T4 : 3 cross peaks T1/T4/T2+T3 : 2 cross peaks T2/T3/T1+T4 : 2 cross peaks T2/T4/T1+T3 : 3 cross peaks 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°

29Si MAS NMR spectrum of highly siliceous mordenite T2 + T4 T1 29Si MAS NMR spectrum of highly siliceous mordenite T3 J-scaled COSY spectrum T1/T3/T2+T4 : 3 cross peaks T1/T4/T2+T3 : 2 cross peaks T2/T3/T1+T4 : 2 cross peaks T2/T4/T1+T3 : 3 cross peaks -110 -112 -114 -116 -118 ppm

29Si MAS NMR spectra of ultrastabilized and hydrothermally realuminated zeolites 1 Si/Al = 2.56 3 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)

Chemical reactions in zeolites {C} + H2O CO + H2 (water gas reaction) ……. + x O2 (n-x) CO + n H2 + x CO2 (water gas shift)

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) 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 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 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 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 0 -5 -10 -15 40 30 20 10 0 -10 ppm

13C MAS NMR spectrum of H-ZSM-5 with 50 torr of adsorbed MeOH heated to 300 °C for 35 mins scalar coupling 0 -5 -10 -15 1JCH = 125 Hz a quintet with ratio 1:4:6:4:1 is expected for methane 40 30 20 10 0 -10 ppm

Heteronuclear 2D J-resolved 13C MAS NMR spectrum 300 200 100 0 Hz -100 -200 -300 26 24 22 18 17 16 15 -11 -12 ppm

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 Methane Ethane Propane Cyclopropane n-Butane Isobutane (n-Pentane) Isopentane n-Hexane n-Heptane 0 -5 -10 -15 40 30 20 10 0 -10 ppm

Methylated aromatic products * CO * * * * 190 185 180 140 135 130 125 ppm

129Xe NMR as a sensitive tool for materials 0: reference S: surface collisions Xe: Xe-Xe collisions E: electric field effect M: paramagnetic species

129Xe as a sensitive probe for various zeolites ZK4 ZSM-5 1021 NaY ZSM-11 K - L Xe atoms /g omega 1020 60 80 100 120 140 ppm

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 of alkyl substituted HBC‘s R = C12H25 Hexadodecyl-hexa-peri-hexabenzocoronene (HBC-C12)

Charge carrier mobility in HHTT

1H DQ MAS NMR spectra of HBC-C12 a-deuterated fully protonated

Proposed stacking model based on solid state NMR

„Graphitic“ stacking

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: b and g are Euler angles relating the PAF of the diploar coupling tensor to the rotor fixed reference frame with -> distance information in a rigid system, or indication of mobility: Ref.: Graf et al. J. Chem. Phys. 1997, 106, 885

Homonuclear correlation between I = 1/2 spins

DQ spinning side band patterns aromatic protons at 8.3 ppm (crystalline phase) DQ spinning side band patterns wR = 35 kHz aromatic protons at 6.2 ppm (LC phase) wR = 10 kHz aliphatic protons at 1.2 ppm (crystalline phase) wR = 35 kHz fitted dipolar coupling constants

Effect of additional phenyl spacers R = -C12H25 or -C6H4-C12H25

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 Let us have a tour of solid state NMR following Professor Malcolm H. Levitt.