Dynamic Nuclear Magnetic Resonance Study Research Articles

A Small Change in Structure, a Big Change in Flexibility.

Studies of the rotational barrier energy of the amide bond using quantum computing and nuclear magnetic resonance (NMR) are focused mainly on its use as a model of the peptide bond. The results of these studies are valuable not only in terms of the fundamental conformational properties of amide bonds, but also in the design of molecular machines, which have recently attracted interest. We investigate the fluxionality of the amide and enamide bonds of compound 3-[(E)-(dimethylamino)methylidene]-1,1-dimethylurea using advanced dynamic NMR experiments and a theoretical evaluation of the density functional theory (DFT) calculation. The dynamic NMR study shows restricted rotation around the amide group (16.4 kcal/mol) and a very high barrier around the enamine group (18.6 kcal/mol). In a structurally similar compound, (E)-3-(dimethylamino)-N,N-dimethylacrylamide (N atom is replaced by CH), the amide barrier is 12.4 kcal/mol and the enamine barrier is 11.7 kcal/mol. The DFT studies of both compounds reveal the electronic origin of this phenomenon. Theoretical calculations reveal the origin of the higher enamine barrier. The better delocalization of the lone pair of electrons on the end nitrogen atom into the antibonding orbital of the neighboring C-N double bond leads to the better stabilization of the ground state, and this leads to a greater increase in the enamine barrier.

Acrylamide derivatives: A dynamic nuclear magnetic resonance study.

Substituted acrylamides have found an extensive application in organic and medical chemistry; therefore, it is very important to get insight into their features such as electronic structure, spectral properties, and stereochemical transformations. A correct interpretation of the chemical behavior and biological activity of these heteroatomic systems is impossible without knowledge of the structure of stereodynamic forms and factors determining their relative stability. The structure and peculiarities of stereodynamic behavior of substituted acrylamides and their model compounds were studied by dynamic and multinuclear 1 H, 13 C, and 15 N nuclear magnetic resonance (NMR) spectroscopy in CDCl3 and DMSO-d6 solution. It has been established that acrylamides in solution are realized as Z- and E-isomers, with the E-rotamer being somewhat predominant. The obtained experimental values of the free activation energy of rotamers vary within 15-17 kcal/mol, depending on the stereochemical structure of the molecule. 15 N NMR spectroscopy is the most reliable and fastest method for determining the structural and stereochemical features of nitrogen-containing compounds.

Physical aging of PC:PS blends: Dynamic mechanical analysis and nuclear magnetic resonance studies

AbstractThe effect of physical aging of the partially miscible blend of polycarbonate:polystyrene (PC:PS) at temperatures near the glass transition temperature (Tg) of the PS was studied as a function of time. For this purpose, blends of PC and PS with different ratios were elaborated and characterized using SEM, FTIR, DSC, and DMA techniques. The results indicated the presence of weak interaction upon blending with a maximum of interaction for the 50:50 blend. The effect of physical aging on the latter was then investigated via DMA, DSC, and NMR analyses. The DMA results showed that both phases were sensitive to aging. The effect was found to be strongly dependent on both the temperature and time. The aging of PC:PS blend was also found to trap stress during the process which induced an instability in the viscoelastic behavior. The latter was found to be associated with a phase‐separation morphology of the blend and influenced by its composition. The NMR analysis also showed a pronounced distortion of the conformation combined with increasing molecular motion. These effects were found to be important for aging below the PS's Tg.

Расчет эффективности удвоения частоты излучения субтерагерцового гиротрона за счет решеточной нелинейности в монокристаллической пластине InP

In this work, we calculated the efficiency of second harmonic generation for sub-THz gyrotron radiation in a single-crystal InP plate embedded in a conical metal waveguide. For the values of the losses at the doubled frequency (depending on the degree of purity of the InP crystal), the dimensions of the wafer are revealed that provide the optimal effective frequency conversion. Thus, the conversion factor f –>2f can reach 5 W/kW^2 when pumped at a frequency of 263 GHz and a loss of alpha_2f = 0.1 cm^-1. The possibility of a noticeable increase in the efficiency of frequency doubling with fine tuning of the phase matching due to the selection of the size of the submicron gap between the InP plate and the plates of the metal waveguide is shown. The results obtained can be used to solve applied problems in the field of dynamic nuclear polarization spectroscopy and nuclear magnetic resonance studies.

NMR studies of molecular ordering and molecular dynamics in a chiral liquid crystal with the SmC_{α}^{*} phase.

Molecular dynamics of the antiferroelectric liquid crystal 4'-(octyloxy)biphenyl-4-carboxylate2-fluoro-4-[(octyl-2-yloxy)carbonyl]phenyl (abbreviated as D16) was investigated using different nuclear magnetic resonance (NMR) techniques. D16 molecules form a smectic-C_{α}^{*} phase (SmC_{α}^{*}) in an extremely wide temperature range (∼10 °C). Due to a small tilt of the molecules, this phase is characterized by short switching times, important for new photonic applications. The proton spin-lattice relaxation times were measured in isotropic (Iso), smectic-A (SmA), and SmC_{α}^{*} phases over a wide frequency range of five decades, with conventional and fast field-cycling NMR techniques. This approach allowed a comparison of the essential processes of molecular dynamics taking place in these phases. On the basis of NMR relaxometry measurements, we present a description of the motional behavior of liquid crystal molecules forming SmC_{α}^{*}. Pretransitional effects were observed in wide temperature ranges in both the isotropic and SmA phases in D16. The ^{1}H fast field-cycling NMR measurements were supplemented with NMR diffusometry and ^{19}F NMR spectroscopy.

(Invited) Lithium Ion Conductors – between Model Systems and Battery Materials

Lithium ion conductors continue to attract huge attention mainly due to the need for improved Li ion batteries, although “post-Li” energy storage systems are also being explored. In any case, basic research dealing with, e.g., the elementary ion jump process, the dimensionality of diffusion or the influence of structural disorder – besides being a field in its own right – is indispensable for those applications, too. Here, exemplary results of our group on Li ion conductors are reviewed. Interestingly, materials used as model systems for basic questions quite often are also potential battery materials, i.e. solid electrolytes or electrodes, and vice versa. An early example of a cathode material has been the intercalation compound LixTiS2 which turned out to be a model system for two-dimensional Li diffusion, involving a unique jump process over many decades, as was proven by a combination of nuclear magnetic resonance (NMR) techniques. Besides the layer-structured also the cubic modification as well as nanocrystalline and amorphous forms were examined with respect to dimensionality and disorder effects.. Anode materials studied by us primarily from a fundamental point of view have been Li x C6 (0<x≤1), Li4+x Ti5O12 (0<x<3) and, as one of the silicides, Li12Si7. In Li12Si7 very fast quasi one-dimensional Li diffusion was detected. Among the potential electrolytes for all-solid-state Li ion batteries, Li7La3Zr2O12 was investigated in some detail also with respect to the influence of doping and defects on Li diffusivity. The examples to be presented extensively involve NMR, which now is an established materials science method for Li ion dynamics [1, 2], but also impedance spectroscopy [3], mass spectrometry [4] and neutron reflectometry [5] have been applied in the Li ion transport studies.[1] C. V. Chandran, P. Heitjans, Solid-State NMR Studies of Lithium Ion Dynamics Across Materials Classes, Annual Reports on NMR Spectroscopy 89 (2016) 1-102.[2] K. Volgmann, V. Epp, J. Langer, B. Stanje, J. Heine, S. Nakhal, M. Lerch, M. Wilkening, P. Heitjans, Solid-State NMR to Study Translational Li Ion Dynamics in Solids with Low-Dimensional Diffusion Pathways, Z. Phys. Chem. 231 (2017) 1215–1241. [3] J. Rahn, E. Hüger, L. Dörrer, B. Ruprecht, P. Heitjans, H. Schmid, Li Self-Diffusion in Lithium Niobate Single Crystals at Low Temperatures, Phys. Chem. Chem. Phys. 116 (2012) 2427–2433. [4] A.-M. Welsch, H. Behrens, I. Horn, S. Roß, P. Heitjans, Self-Diffusion of Lithium in LiAlSi2O6 Glasses Studied Using Mass Spectrometry, J. Phys. Chem. A 116 (2012) 309–318. [5] F. Strauß, E. Hüger, P. Heitjans, T. Geue, J. Stahn, H. Schmidt, Li Permeation through Thin Lithium-Silicon Films for Battery Applications Investigated by Neutron Reflectometry, Energy Technology 12 (2016) 1582–1587.

Dynamic NMR Study of Model CMP Slurry Containing Silica Particles as Abrasives

Chemical mechanical planarization (CMP) should provide a good surface planarity with minimal surface defectivity. Since CMP slurries are multi-component systems, it is very important to understand the various processes and interactions taking place in such slurries. Several techniques have been employed for such task, however, most of them lack the molecular recognition to investigate molecular interactions without adding probes which in turn increase complexity and might alter the microenvironment of the slurry. Nuclear magnetic resonance (NMR) is a powerful technique that can be employed in such study.The longitudinal relaxation times (T1) of the different components of CMP slurries were measured using Spin Echo-NMR (SE-NMR) at a constant temperature. The fact that NMR is non-invasive and gives information on the molecular level gives more advantage to the technique. The model CMP slurry was prepared in D2O to enable monitoring of T1 for the various components' protons. SE-NMR provide a very powerful tool to study the various interactions and adsorption processes that take place in a model CMP silica based slurry which contains BTA and/or glycine and/or Cu+2 ions. It was found that BTA is very competitive towards complexation with Cu+2 ions and BTA-Cu complex adsorbs on silica surface.

Supersize Cp! Tetrabenzo[a,c,g,i]fluorenyl complexes of yttrium

The synthesis of tetrabenzo[a,c,g,i]fluorenyl (Tbf) yttrium dialkyl complexes, (Tbf)Y(CH2SiMe3)2(L) (L = tetrahydrofuran (THF), 1; L = bipy, 2), by direct protonolysis of the tris(alkyl) complex, Y(CH2SiMe3)3(THF)2, are reported. The X-ray crystal structures of 1 and 2 display the helical twisting typically observed for the Tbf ligand. Dynamic nuclear magnetic resonance (NMR) studies on 1 show a barrier to Tbf helical inversion (epimerization or “wagging”) of 38.1 ± 0.5 kJ mol−1. The reaction of 1 with acidic hydrocarbons such as 1,3-bis(trimethylsilyl)cyclopentadiene or trimethylsilylacetylene results in protonolysis to form the mixed Cp derivative [(Tbf){C5H3(SiMe3)2}Y(CH2SiMe3)(THF)] (3) or [(Tbf)Y(CCSiMe3)2(THF)]n (4), respectively. In the case of 4, a small amount of the trinuclear cluster (Tbf)Y3(μ3-CCSiMe3)2(μ2-CCSiMe3)3(CCSiMe3)3(THF)2 (5) was isolated and characterized by X-ray crystallography. Dialkyl 1 undergoes smooth insertion of trimethylsilyl isocyanate to afford [(Tbf)Y{κ2-(N,O)-Me3SiN(Me3SiCH2)CO}2(THF)] (6) but it does not react with alkenes. Treating 1 with [Ph3C]+[B(C6F5)4]− in bromobenzene generates a moderately active ethylene polymerization catalyst (36 kg mol−1 h−1 bar−1).

Expanded Substrate Activity of OXA-24/40 in Carbapenem-Resistant Acinetobacter baumannii Involves Enhanced Binding Loop Flexibility

Gram-negative bacteria resist β-lactam antibiotics primarily by deploying β-lactamase proteins that hydrolytically destroy the antibiotics. In clinical settings, these bacteria are producing variant β-lactamases with "gain-of-activity" mutations that inactivate a broader range of β-lactams. Learning how these mutations broaden substrate activity is important for coping with β-lactam resistance. Here, we investigate a gain of activity mutation in OXA-24/40, a carbapenem-hydrolyzing class D β-lactamase (CHDL) in Acinetobacter baumannii. OXA-24/40 was originally active against penicillin and carbapenem classes of β-lactams, but a clinical variant of OXA-24/40, the single-site substitution mutant P227S, has emerged with expanded activity that now includes advanced cephalosporins and the monobactam aztreonam. Using solution-state nuclear magnetic resonance (NMR) spectroscopy, we have compared the site-specific backbone dynamics of wild-type OXA-24/40 and the P227S variant. P227S changes local backbone flexibility in segments that are important for both binding and hydrolysis of carbapenem and cephalosporin substrates. Our results suggest that mutation-induced changes in sequence-specific dynamics can expand substrate activity and thus highlight the role of protein conformational dynamics in antibiotic resistance. To the best of our knowledge, this is the first NMR study of CHDL conformational dynamics and its impact on the expansion of β-lactam antibiotic resistance.

Synthesis and dynamic NMR study of zwitterionic salts obtained from N,N′-dimethylbarbituric acid, benzaldehydes, and N,N,N′,N′-tetramethylguanidine

A synthesis of stable charge-separated tetramethylguanidinium-barbituric acid zwitterionic salts is developed through a one-pot three-component reaction of N,N′-dimethylbarbituric acid, benzaldehydes, and N,N,N′,N′-tetramethylguanidine in CH2Cl2 at room temperature. A dynamic effect was observed in the 1H nuclear magnetic resonance (NMR) spectrum of 5-[[bis(dimethylamino)methylene)ammonio](4-methylphenyl)methyl]-1,3-dimethyl-2,4,6-trioxohexahydropyrimidin-5-ide as a result of restricted rotation (ΔG ≠ = 69 kJ/mol) around the Me2N–C bonds of the guanidinium moiety.

High-temperature in situ11B NMR study of network dynamics in boron-containing glass-forming liquids

In situ high-temperature nuclear magnetic resonance (NMR) spectroscopy can be very useful for probing changes in structure and dynamics in glass-forming liquids, and is a unique method for observing chemical exchange among structural species ( e.g. BO 3–BO 4, Q n–Q n+1, and NBO–BO) at the seconds to microseconds time scales. High-temperature 11B MAS NMR line shape measurements were made at about 100 K above the glass transitions on (Na 2O) 0.3(B 2O 3) 0.7 and (Na 2O) 0.2(B 2O 3) 0.21(Al 2O 3) 0.08(SiO 2) 0.51 glass-forming liquids. BO 3 and BO 4 groups are well resolved in 11B MAS NMR spectra at 14.1 T with sample spinning at 5000 Hz. At higher temperatures, partial peak coalescence occurred due to exchange of BO 3 and BO 4. Temperature effects on borate speciation were also determined by varying the fictive temperature ( T f ) of glasses, where T f estimated from differential scanning calorimetry measurements. We combined these complementary data sets to model structural exchange in the liquid state. The time scale of BO 3–BO 4 exchange from NMR data, τ NMR, appears to be “decoupled” from that of the macroscopic shear relaxation process τ s derived from the viscosity, however, at higher temperatures, τ s approaches τ NMR. The “decoupling” at lower temperature may be related to intermediate-range compositional heterogeneities, and/or fast modifier cation diffusivities which trigger “unsuccessful” network exchange events.

Synthesis and Dynamic NMR Study of a Functionalized Sulfonamide Phosphonate Diester

Protonation of the highly reactive 1:1 intermediate produced in the reaction between triphenylphosphite and activated acetylene by sulfonamide leads to a phosphonate ylide, which undergoes methanol elimination in the presence of moisture to produce a highly functionalized sulfonamide phosphonate diester. A dynamic nuclear magnetic resonance (NMR) effect is observed in the 1H NMR spectra of this compound as a result of restricted rotation around the single C‒N bond. The coalescence temperature was observed at TC = 352.5 K, and the free energy of activation (ΔG#) for this process is 75.6 ± 2 kJ.mol−1. GRAPHICAL ABSTRACT

ChemInform Abstract: Syntheses and Dynamic Nuclear Magnetic Resonance Studies of Complexes of Trimethylplatinum(IV) Iodide with Ditelluroether Chelate Ligands.

Trimethylplatinum(IV) iodide complexes with ditelluroether ligands, namely [PtlMe3(L–L)][L–L = MeTe(CH2)3TeMe, PhTe(CH2)3TePh or o-C6H4(TeMe)2] have been isolated as pure solids. 195Pt-{1H} and 125Te-{1H} NMR studies show that ambient-temperature solutions of the complexes with aliphatic ligand backbones consist predominantly of DL isomers. The complex [PtlMe3{MeTe(CH2)3TeMe}] also exists in significant amounts of both meso forms. In contrast, the meso-1 form is present in only very low abundance in [PtlMe3{PhTe(CH2)3TePh}] and [PtlMe3{o-C6H4(TeMe)2}]. Pyramidal tellurium inversion interconverts these isomeric species and precise rates of this process were measured at near-ambient temperatures by 195Pt-{1H} and 125Te-{1H} NMR two-dimensional exchange spectroscopy experiments, or by 1H one-dimensional NMR bandshape analysis at above-ambient temperatures in the case of [PtlMe3{o-C6H4(TeMe)2}]. Tellurium pyramidal inversion-energy barriers [ΔG‡(298.15 K)] were in the range 70–84 kJ mol–1, reflecting the nature of the the substituent at Te and the ligand backbone. Comparison of the tellurium inversion energy in [PtlMe3{MeTe(CH2)3TeMe}] with data for Se and S in analogous complexes of chalcogen ligands establishes the trend in inversion energies, namely Te > Se > S, on a firm quantitative basis.

Dynamic NMR study and theoretical calculations on the conformational exchange of valsartan and related compounds

Valsartan (1), an antihypertensive drug of the sartan family, and three related compounds, 3-methyl-2-((2'-(1-methyl-1H-tetrazol-5-yl)biphenyl-4-ylmethyl) pentanoylamino)butyric acid (2), 3-isopropyl-6-propyl-4-(2'-(1H-tetrazol-5-yl)biphenyl-4-ylmethyl) morpholine-2,5-dione (3), and 3-isopropyl-6-propyl-4-(4'-(1H-tetrazol-5-yl)biphenyl4-ylmethyl) morpholine-2,5-dione (4), were studied by nuclear magnetic resonance (NMR) spectroscopy. Assignment of (1)H and (13)C NMR resonances for the compounds were completed using COSY, HSQC and HMBC techniques. It was found that each of the compounds 1, 2, and 4 had two sets of (1)H and (13)C resonances, suggesting the presence of two conformers in solution. Based on NOESY experiments at different temperatures, thermodynamic parameters of the conformational exchange process were deduced for these compounds. The exchange barrier was found to be 17.9 +/- 0.7, 18.5 +/- 0.8, and 17.7 +/- 0.6 kcal mol(-1) with the corresponding free energy difference (DeltaG) of 0.32 +/- 0.04, 0.23 +/- 0.01, and 0.13 +/- 0.04 kcal mol(-1) for 1, 2, and 4, respectively, at 298 K. Two conformations of valsartan were elucidated by NMR spectroscopy and quantum chemistry calculation. The results showed that two conformers of valsartan interchange via rotation about the C(O)--N bond.

New Tools Provide New Insights in NMR Studies of Protein Dynamics

There is growing evidence that structural flexibility plays a central role in the function of protein molecules. Many of the experimental data come from nuclear magnetic resonance (NMR) spectroscopy, a technique that allows internal motions to be probed with exquisite time and spatial resolution. Recent methodological advancements in NMR have extended our ability to characterize protein dynamics and promise to shed new light on the mechanisms by which these molecules function. Here, we present a brief overview of some of the new methods, together with applications that illustrate the level of detail at which protein motions can now be observed.

NMR Study of Structure and Dynamics of Ionic Multiplets in Ethylene−Methacrylic Acid Ionomers

Structural and dynamical properties of ionic multiplets in poly(ethylene-co-methacrylic acid) ionomer neutralized with Na ions were studied by 23Na nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). It was found that the low-temperature peak in DSC spectra is affected by relaxation, compression, and hydration and is related to structure in proximity to ionic multiplets, instead of multiplets themselves. The distance between Na ions in ionic multiplet was determined on the basis of a second moment measurement, suggesting that multiplets are composed of close-packed Na+−O- ionic pairs. Motional narrowing of 23Na NMR line width and transverse relaxation measurement indicate that the time scale of motion of Na or its surrounding is on the order of a few hundred microseconds near room temperature.

NMR Study of Lithium Dynamics and Molecular Motions in a Diethylamine−Molybdenum Disulfide Intercalation Compound

Measurements of the 13C, 7Li, and 1H nuclear magnetic resonance (NMR) of the nanocomposite formed by the intercalation of lithium and diethylamine in molybdenum disulfide, Li0.1MoS2[(C2H5)2NH]0.2, are reported. The strong Li−Li dipolar interaction strength, calculated from the 7Li NMR decoupling data, suggests the formation of lithium clusters. The dimensional restriction of the available space between the host layers supports a hypothesis that is based on the formation of Li3 clusters stabilized by amine ligands. The lithium relaxation is mainly due to the interaction between the quadrupolar moment of the 7Li nuclei and the fluctuating electric field gradient at the site of the nucleus, produced by the surrounding charge distribution. The dynamical parameters obtained from the 7Li temperature dependence of the spin−lattice relaxation indicate a high lithium mobility, which is attributed to the fast exchange motion of the lithium ions between the coordination sites within each Li3 aggregate. The 1H line s...

15N NMR study of nitrate ion structure and dynamics in hydrotalcite-like compounds

We report here the first nuclear magnetic resonance (NMR) spectroscopic study of the dynamical and structural behavior of nitrate on the surface and in the interlayer of hydrotalcite-like compounds \(^{15}NO_{3}^{{-}}-HT\) . Spectroscopically resolvable surface-absorbed and interlayer \(NO_{3}^{{-}}\) have dramatically different dynamical characteristics. The interlayer nitrate shows a well defined, temperature independent uniaxial chemical shift anisotropy (CSA) powder pattern. It is rigidly held or perhaps undergoes rotation about its threefold axis at all temperatures between −100 °C and +80 °C and relative humidities (R.H.) from 0 to 100% at room temperature. For surface nitrate, however, the dynamical behavior depends substantially on temperature and relative humidity. Analysis of the temperature and R.H. dependences of the peak width yields reorientational frequencies which increase from essentially 0 at −100 °C to 2.6 × 10 5 Hz at 60 °C and an activation energy of 12.6 kJ/mol. For example, for samples at R.H. = 33%, the surface nitrate is isotropically mobile at frequencies greater than 10 5 Hz at room temperature, but it becomes rigid or only rotates on its threefold axis at −100 °C. For dry samples and samples heated at 200 °C (R.H. near 0%), the surface nitrate is not isotropically averaged at room temperature. In contrast to our previous results for 35 Cl − -containing hydrotalcite ( 35 Cl − -HT), no NMR detectable structural phase transition is observed for \(^{15}NO_{3}^{{-}}-HT\) . The mobility of interlayer nitrate in HT is intermediate between that of carbonate and chloride.

The sub- Tg relaxations in pure and antiplasticized model epoxy networks as studied by high resolution creep rate spectroscopy

An original laser-interferometric creep rate spectroscopy method was used for studying the molecular mobility in the glassy state of a series of ‘model’ epoxy-amine networks varying in cross-link density and rigidity. The experiments were carried out over the temperature range 115–300 K, which covers the regions where the secondary relaxations are expected to occur. The creep rate spectra (CRS) obtained at low compressive stresses exhibited systematically multiple creep rate ε ̇ peaks, irrespective of the applied stress and the experimental time in the ranges under consideration, namely 20–40 MPa and 10–40 s, respectively. Data analysis was based on the inspection of the major peaks of the CRS without entering much into the details of the fine structure. The peaks assigned to the β relaxation were shown to depend on the changes in network cross-link density and to the addition of antiplasticizing molecules in the same way as reported earlier from dynamic mechanical analysis (DMA) and 13C nuclear magnetic resonance (NMR) studies. In the case of the resins cured with aromatic amines, for which no γ relaxation is evidenced by DMA, creep rate spectroscopy allowed the detection of an additional relaxation, so called γ′, at temperatures well below the β process. It was tentatively assigned to DMA-inactive motions of the aromatic amine residues, i.e. to the phenyl ring flips of the diphenylmethane units.

NMR Study of Dynamics and Evolution of Guest Molecules in Kaolinite/Dimethyl Sulfoxide Intercalation Compound

AbstractMotion of the guest molecules in kaolinite/dimethyl sulfoxide (DMSO) intercalation compounds Al2Si2O5(OH)4∙(CH3)2SO has been studied by means of solid-state nuclear magnetic resonance (NMR) in the temperature range between 300 and 380 K, which is just below the evolution temperature. The 13C magic angle spinning (MAS) NMR spectra show 2 inequivalent methyl carbons: 1 methyl carbon is keyed in the ditrigonal hole of the silicate sheet, while the other is located parallel to the sheet. Above 320 K, the 2 peaks have different intensities, suggesting that the keyed methyl groups from some of the DMSO molecules are released from the hole. The 2H NMR spectra have been measured for kaolinite/DMSO-d6 intercalate. The methyl group of the interlayer DMSO molecule undergoes free rotation around its C3 axis over the temperature range studied. The axis of rotation is fixed at the low temperature (about 160 K), and the methyl group initiates a wobbling motion whose amplitude increases with temperature. The wobbling angles have an anisotropy, estimated from theoretical analysis of the 2H spectral line shapes. The DMSO molecules released from the silicate layer undergo anisotropic rotation of the whole molecule.