Pure NaAlH4, TiCl3-doped NaAlH4, and pure Na3AlH6 were characterized using 1H, 23Na, and 27Al solid-state NMR. The signal intensities and linewidths of 1H NMR spectra using several spin echo sequences and backprediction of a single pulse experiment were compared to find the optimal experiment to measure wide-line NMR spectra of the alanates. Second moment calculations using the Van Vleck equations compared with fits of the dipolar coupling line broadening confirm that NaAlH4 has a rigid crystal lattice. On the other hand, for Na3AlH6, a narrowing of the proton and aluminum lineshape was observed, indicating a fast rotational motion of AlH6 clusters at room temperature. A broadening of the 1H and 27Al linewidth was observed upon lowering the temperature. This process is successfully described using thermally activated rotational jumps of AlH6 clusters assuming a fast rotational motion around one single C4 axis and a slower rotation around the other two C4 axes with an activation barrier of Ea = 25 kJ/mol and an attempt frequency of v0 = 4 × 1010 Hz.

•We present a novel application of nutation NMR.•The spectral nutation profile of satellite transitions (STs) is analysed in detail.•STs of symmetric sites are discriminated from broadened CTs of distorted sites.•The 35Cl spectrum of a Ziegler-Natta catalyst model system is unambiguously assigned.In this contribution we used solid state 35Cl (I = 3/2) quadrupolar NMR to study a MgCl2/2,2-dimethyl-1,3-dimethoxypropane (DMDOMe) adduct that serves as a model system for Ziegler-Natta catalysis. Employing large Radio-Frequency (RF) field strengths we observe three spectral features with strongly varying line widths. The assignment of the spectra is complicated because of the large difference in quadrupolar interactions experienced by the different sites in the system. The satellite transitions (ST) of relatively well-defined bulk Cl sites are partially excited and may overlap with the central transition (CT) resonances of more distorted surface sites. We show that nutation NMR of the ST of I = 3/2 spins yields a unique pattern that makes a clear distinction between an extensively broadened central transition and the satellite transitions of a component with a smaller quadrupolar interaction. This allows us to unambiguously unravel the spectra of the MgCl2 adduct showing that we observe CT and ST of the bulk phase of MgCl2-nanoparticles with a CQ of 4.6 MHz together with the CT of surface sites displaying an average CQ of ∼10 MHz.Download high-res image (180KB)Download full-size image

Microfluidic stripline NMR technology not only allows for NMR experiments to be performed on small sample volumes in the submicroliter range, but also experiments can easily be performed in continuous flow because of the stripline’s favorable geometry. In this study we demonstrate the possibility of dual-channel operation of a microfluidic stripline NMR setup showing one- and two-dimensional 1H, 13C and heteronuclear NMR experiments under continuous flow. We performed experiments on ethyl crotonate and menthol, using three different types of NMR chips aiming for straightforward microfluidic connectivity. The detection volumes are approximately 150 and 250 nL, while flow rates ranging from 0.5 μL/min to 15 μL/min have been employed. We show that in continuous flow the pulse delay is determined by the replenishment time of the detector volume, if the sample trajectory in the magnet toward NMR detector is long enough to polarize the spin systems. This can considerably speed up quantitative measurement of samples needing signal averaging. So it can be beneficial to perform continuous flow measurements in this setup for analysis of, e.g., reactive, unstable, or mass-limited compounds.

In order to better understand the structure and dynamics of methylammonium lead halide perovskites, we performed NMR, NQR, and DFT studies of CH3NH3PbI3 in the tetragonal and cubic phase. Our results indicate that the space group of the tetragonal phase is the nonpolar I4/mcm. The highly dynamic methylammonium moiety shows no indication of the occurrence of additional orientations of the C–N bond close to the c-axis at temperatures approaching the cubic phase. Crystal quality effects are shown to influence the 14N NMR and 127I NQR spectra, and the effects of high-temperature annealing on defects can be observed. A strong increase in T2 relaxation time of the 207Pb NMR signal on cooling is found, and is an indication of slow motions in the PbI6 octahedra at room temperature. These results aid in the understanding of the structure of methylammonium lead halides and enable further studies of defects in these materials.

In this paper the short and long range order in In0.483Ga0.517P thin films is investigated by solid-state Nuclear Magnetic Resonance (NMR) spectroscopy. To this end two samples were grown on a GaAs substrate by metal–organic vapor phase epitaxy at two different growth-pressures. From band gap energy measurements, CuPt long range order parameters of SCuPt = 0.22 and 0.39 were deduced, respectively. In the 31P spectrum five resonances are observed corresponding to the five possible P(GanIn4−n), n = 0–4, coordinations whose relative intensities correspond to the order in the material, but the intensity variations for order parameters between 0 and 0.5 are minimal. 69Ga, 71Ga and 115In (MQ)MAS spectra were acquired to analyze the quadrupolar and chemical shift distributions related to the (dis)order in these materials in more detail. All these spectra clearly reflect the disorder in the sample and do not show the presence of highly ordered domains. The difference in the order parameter in the sample is not clearly reflected in the spectra. 31P chemical shifts were calculated using Density Functional Theory. The experimentally observed shifts are well reproduced with a simple random model of the disorder, thus confirming the assignment of the resonances. The 31P chemical shifts are very sensitive to changes in the lattice parameter and chemical surroundings. These effects nearly compensate and explain why the 31P chemical shifts in pure InP and GaP are nearly identical whereas a large difference would be expected based on the observed shift difference for the P[In4] and P[Ga4] coordinations in In0.483Ga0.517P.

To be able to study mass-limited samples and small single crystals, a triple resonance micro-magic angle spinning (μMAS) probehead for the application of high-resolution solid-state NMR of nanoliter samples was developed. Due to its excellent rf performance this allows us to explore the limits of proton NMR resolution in strongly coupled solids. Using homonuclear decoupling we obtain unprecedented 1H linewidths for a single crystal of glycine (Δν(CH2) = 0.14 ppm) at high field (20 T) in a directly detected spectrum. The triple channel design allowed the recording of high-resolution μMAS 13C–15N correlations of [U-13C–15N] arginine HCl and shows that the superior 1H resolution opens the way for high-sensitivity inverse detection of heteronuclei even at moderate spinning speeds and rf-fields. Efficient decoupling leads to long coherence times which can be exploited in many correlation experiments.

•An implementation of nutation NMR of quadrupolar nuclei using RF fields up to 1.17 MHz.•The implementation of a frequency jump to circumvent problems resulting from pulse transients.•Nutation NMR spectra of 23Na and 139La nuclei with very large quadrupolar interaction parameters.Owing to the introduction of microcoils, high RF field strength nutation NMR is a viable candidate for the study of quadrupolar nuclei with strong quadrupolar couplings, not accessible using contemporary NMR techniques. We show powder 2323Na nutation spectra on sodium nitrite for RF field strengths of up to 1170 kHz, that conform to theoretical predictions. For lanthanum fluoride powder, 139139La nutation spectra taken at elevated RF field amplitudes show clear discrepancies when compared to the theory. These errors are shown to be mainly caused by pulse transients at the end of the pulse, which proved to be detrimental to the shape of the nutation spectra. Using a nutation pulse which ends in a sudden frequency jump, we show that these errors can be reduced, and nutation spectra that conform to theory can be readily acquired. This enables nutation NMR for the study of quadrupolar nuclei with a strong quadrupolar coupling, bridging the gap between NMR, which can only analyse nuclei with a weak to medium quadrupolar coupling, and NQR, were extensive searching for the right quadrupolar frequency is the limiting factor.

MgCl2 is a vital component of Ziegler–Natta catalysts for olefin polymerization. Here we synthesized anhydrous MgCl2 using different drying protocols and exploited 1H NMR to quantify the proton content. We report on our study of neat and ball-milled MgCl2 samples by means of 25Mg and 35Cl solid-state NMR. DFT calculations of the quadrupole tensor aid in analysis of the spectra. The results show that, due to the morphology of the neat particles, a preferred orientation is induced which manifests itself in unusual powder line shapes. Ball milling reduces particle size, which subsequently leads to a small distribution of quadrupole parameters for the bulk. Surface sites, highly relevant for catalysis, are not directly observed, due to their broad lines of low intensity.

Aramid fibers are of practical interest due to their high tensile strength, high elastic modulus, low elongation at breakage, and thermomechanical stability. Here we combine high-resolution solid-state NMR and density functional theory (DFT) calculations to gain insight into the details of the molecular packing of p-phenylene terephthalamides (PPTA). On the basis of the four models discussed thus far in the literature, we create a family of 16 possible structures. Calculations relate 1H and 13C chemical shifts obtained from experiments to structural aspects. Nucleus independent chemical shift (NICS) calculations show that ring currents and σ–π interactions as well as hydrogen bonding influence the chemical shifts on the rings. We obtain an unambiguous assignment, which differs from the literature data for carbon, for all resonances relating to the repeating unit of PPTA and obtain new insights into the possible packings of the PPTA units within the unit cell.

Highlights•In-depth introduction of Ziegler–Natta catalysis.•Overview of solid-state NMR research into Ziegler–Natta based catalysis for the production of polyolefines.•Overview of solid-state NMR research into metallocene based catalysis for the production of polyolefines.Ziegler–Natta catalysts are the workhorses of polyolefin production. However, although they have been used and intensively studied for half a century, there is still no comprehensive picture of their mechanistic operation. New techniques are needed to gain more insight in these catalysts. Solid-state NMR has reached a high level of sophistication over the last few decades and holds great promise for providing a deeper insight in Ziegler–Natta catalysis. This review outlines the possibilities for solid-state NMR to characterize the different components and interactions in Ziegler–Natta and metallocene catalysts. An overview is given of some of the expected mechanisms and the resulting polymer microstructure and other characteristics. In the second part of this review we present studies that have used solid-state NMR to investigate the composition of Ziegler–Natta and metallocene catalysts or the interactions between their components.Graphical abstract

Oxygen-containing yttrium hydride thin films show a unique reversible change in optical properties as a result of illumination. In this article, different solid-state NMR methods are used to follow the changes during such a photochromic process. The novel stripline probe technology provides a high sensitivity for NMR experiments on thin film samples with a thickness of approximately 1 μm. A key observation is that these photochromic films show spectral evidence of a highly mobile hydrogen species, which disappears upon illumination with white light. A relaxation back to the transparent phase is observed after a few days, accompanied by the reappearance of the mobile proton NMR signal. These results are compared with NMR experiments on pure yttrium hydride thin films. Magic-angle spinning 1H and 89Y experiments are performed to obtain detailed information in polycrystalline samples and flexible thin films. In particular, the 89Y MAS experiments indicate changes in the local environment of the Y nucleus upon optical illumination. A detailed structural model for the photochromic change is not yet clear, but the present NMR observations may give some hints toward such a model.

We have carried out 75As NMR experiments on a single 5 μm thick epitaxial layer of metal organic chemical vapor deposition (MOCVD) AlxGa1–xAs, with x = 0.522, using a novel stripline based NMR setup. Different arsenic surroundings in the lattice give rise to five As[AlnGa4–n] sites with (n = 0–4). By mounting a thin film of Al0.522Ga0.478As in a home-built NMR probe with rotation stage and stripline detector, we could successfully distinguish different arsenic nearest neighbors coordinations. Furthermore, we were able to observe various 75As quadrupolar tensor orientations for each As[AlnGa4–n] coordination, which gives us a unique insight into the structure of this material. The individual resonances for each of these coordinations appear to be very broad, as a result of the variation in the local symmetry due to the distribution of aluminum and gallium over the lattice. In particular, the NMR resonance of one orientation of the As[Al2Ga2] site is strongly broadened. The line widths prove to be larger than predicted on the basis of the (distribution in) quadrupolar interaction parameters obtained in a previous study of powdered AlxGa1–xAs films (P. J. Knijn et al. Phys. Chem. Chem. Phys. 2010, 12, 11517–11535). In Density Functional Theory (DFT) based calculations, these wider distributions in quadrupolar interaction parameters can be explained by local variations in the first coordination sphere of arsenic, which become apparent when the internal structure is relaxed before quantum mechanical calculations of the Electric Field Gradient Tensors (EFGs). A detailed simulation of the NMR line intensities, taking the actual NMR excitation parameters into account, prove the absence of any kind of local or long-range order in the occupation of the Al/Ga sites in the lattice.

A better understanding of structure-property relations is necessary to design novel materials. In this study, we investigate the morphology and chemical structure of five commercial grades of propylene-based polymers in relation to the change in yield- stress as a function of strain-rate. Substantial emphasis has been laid on understanding the chain microstructure in the relation to chain dynamics in the amorphous phase. Heterogeneous Ziegler–Natta catalysis was used to prepare the samples with differing ratios of propylene and ethylene units. Various analytical techniques such as WAXS, SAXS, solution- and solid-state NMR were employed to characterize their structure. The results indicate a reduction in crystallinity, melting temperature, long-period and crystal thickness with increasing ethylene content. Solid-state NMR data reveal the presence of four components in these samples, which is an extension of the traditional three phase model found in most semi-crystalline polymers. The additional fourth phase is attributed to a rubber-like component that is primarily composed of chain segments rich in ethylene units and shows an increase in chain dynamics with increasing ethylene content in the samples. Mechanical experiments show that yield stress decreases with increase in the amount ethylene which can be correlated to the observed increase in chain dynamics in the amorphous phase.

The success of polyisocyanides as the basic scaffold for functional materials has been attributed to its rigid and highly stable structure. It has been demonstrated that these polymers can be stabilized by formation of inter side chain hydrogen bonds (Cornelissen Science 2001, 293, 676) which in turn has resulted in development of several polyisocyanide based functional materials. Despite the success of the material, the exact structure and conformation of these polymers has been subject of discussions over many years and several structural models based on evidence from different analytical and theoretical methods have been proposed. This study determines the structure of the isocyanide dipeptide polymer using solid-state NMR spectroscopy. Two-dimensional separated-local-field and double-quantum single-quantum spectroscopic methods have been employed to obtain structural constraints for the polymer backbone. These constraints were used to build a molecular model and subsequently subjected to molecular dynamics simulations. The backbone structure of the polyisocyanide is determined to be a 154 helix with hydrogen bonding interactions between n and n + 4 side chains.

The structural and dynamical properties of LiBH4 confined in porous carbon and ordered porous silica are studied using 1H, 7Li, and 11B solid-state NMR. The 11B and 7Li NMR resonances of LiBH4 confined in porous carbon (broad pore size distribution up to <60 nm) are strongly broadened compared to bulk LiBH4. This line broadening is dominated by anisotropic susceptibility effects induced by the nanostructured carbon host. Because of the lack of resolution caused by the anisotropic susceptibility broadening, we studied confined LiBH4 in ordered porous silica (MCM-41 pore size: 1.9 nm). In the 7Li and 11B spectra, a bulk-like LiBH4 resonance is observed together with an additional, more narrow component. Above T = 313 K, this component showed a typical J-coupling pattern in both 11B and 1H spectra corresponding to highly mobile BH4– species. Static 11B solid-state NMR measurements compared with second moment calculations show that these BH4– species not only rotate as in the bulk material but also experience translations through the crystal lattice. Static 7Li measurements show that Li+ is also highly mobile. Therefore, we conclude that nanoconfinement of LiBH4 strongly enhances diffusional mobility of borohydride anions and lithium in this material.

Carbazole functionalized polyisocyanides are known to exhibit excellent electronic properties (E. Schwartz, et al., Chemistry of Materials, 2010, 22, 2597). The functionalities and properties of such materials crucially depend on the organization and stability of the polymer structure. We combine solid-state Nuclear Magnetic Resonance (NMR) experiments with first-principles calculations of isotropic chemical shifts, within the recently developed converse approach, to rationalize the origin of isotropic chemical shifts in the crystalline monomer L-isocyanoalanine 2-(9H-carbazol-9-yl) ethyl amide (monomer 1) and thereby gain insight into the structural organization of its polymer (polymer 2). The use of state-of-the-art solid-state NMR experiments combined with Density Functional Theory (DFT) based calculations allows an unambiguous assignment of all proton and carbon resonances of the monomer. We were able to identify the structure stabilising interactions in the crystal and understand the influence of the molecular packing in the crystal structure on the chemical shift data observed in the NMR spectra. Here the Nuclear Independent Chemical Shift (NICS) approach allows discriminating between ‘physical’ interactions amongst neighboring molecules such as ring-current effects and ‘chemical’ interactions such as hydrogen bonding. This analysis reveals that the isocyanide monomer is stabilized by multiple hydrogen bonds such as a bifurcated hydrogen bond involving –N–H, –C–H and OC– moieties and Ar–H⋯CN– hydrogen bonding (Ar = aromatic group). Based on the geometrical arrangement it is postulated that the carbazole units are involved in the weak σ–π interactions giving rise to a Herringbone packing of the molecules. The chemical shift analysis of the polymer spectra readily establishes the existence of N–H⋯OC hydrogen bonds despite the limited resolution exhibited by the polymer spectra. It is also elucidated that the relative arrangement of the carbazole units in the polymer differs significantly from that of the monomer.

The oxidation products of NaAlH4 were studied using solid-state nuclear magnetic resonance experiments combined with X-ray diffraction (XRD) experiments. We studied the coordination of aluminum with oxygen using single-pulse 27Al experiments. 27Al−{1H} rotational echo double-resonance, 23Na−{27Al}/27Al−{23Na} transfer of population in double-resonance (TRAPDOR), and combined 27Al−23Na TRAPDOR−multiple-quantum magic-angle spinning (MQMAS) experiments were used to get qualitative information about Al−H and Al−Na proximities. These NMR experiments show that the intermediate oxidation product is an amorphous sodium aluminum hydroxide with Al in a tetrahedral coordinated site. A 27Al MQMAS experiment shows distributions of chemical shift and quadrupolar coupling parameters. Therefore, the material is probably highly disordered, and multiple compounds may be present. XRD measurements show that this phase indeed lacks long-range order. The end product contains mainly octahedral coordinated aluminum hydroxide. Crystalline aluminum hydroxides, consisting of gibbsite and bayerite, and sodium carbonate hydrates, Na2CO3·H2O and Na3(CO3)2·2H2O, are observed by XRD measurements. Our results show that relatively harmless and nontoxic compounds are formed. However, the materials should handled carefully because of the strong basicity of compounds like sodium carbonate.

The exact role of catalysts, such as titanium, scandium, or cerium, in improving the hydrogen kinetics in NaAlH4 is not completely understood. Here, we studied the local structure of scandium and the formation of different species in ScCl3-doped NaAlH4 by 23Na, 27Al, and 45Sc NMR. The 27Al and 23Na solid-state NMR spectra of ball-milled ScCl3-doped NaAlH4 mainly show resonances corresponding to NaAlH4, Na3AlH6, Al, and NaCl. The three decomposition products are formed by partial dehydrogenation and reactions with the dopant. The 45Sc NMR spectrum shows resonances corresponding to a distorted ScCl3 phase, a Sc–Al solid solution, and ScH2. After cycling eight times with hydrogen, the Na3AlH6 and Al intensities increase. This can be explained by an incomplete rehydrogenation that is due to a partial reversibility of the first desorption reaction. After cycling under hydrogen, the NaCl intensity strongly increases. This indicates that the doping reaction is not completed after ball-milling. The 45Sc spectra now mainly show the presence of a distorted ScAl3 phase, and a smaller contribution attributed to a distorted ScCl3 phase. After partial dehydrogenation at room temperature, metallic Al and Na3AlH6 are observed. The static 45Sc Carr–Purcell–Meiboom–Gill (CPMG) experiment confirms the presence of the distorted ScAl3 phase. A possible role of Sc in the kinetic enhancement of desorption and uptake of hydrogen in NaAlH4 is that it can act as a grain refiner for metallic Al.

Dynamic nuclear polarization in the liquid state was predicted more than 50 years ago by Overhauser. Its application for NMR sensitivity enhancement has been limited because of intrinsic and experimental problems to apply this method at high magnetic fields. Here we report on 95 GHz DNP experiments using the common TEMPO radical dissolved in water. In an efficient non-radiative microwave resonator, we observe average experimental enhancement factors up to −65. The local enhancement in the center of the resonator is calculated to reach a level of −94 at the highest microwave power. At high microwave power, the DNP enhancement shows a linear increase with no tendency to saturation. The results indicate that a substantial sensitivity enhancement is possible for liquid state NMR in nL sample volumes.

An implementation of rotor-synchronised Magic Angle Spinning (MAS) NMR is presented to determine the quadrupolar coupling tensor values from a single crystal study for half-integer quadrupolar nuclei. Using a microcoil based probehead for studying micro crystals with superior sensitivity, we successfully determine the full quadrupolar tensor of 23Na using a micro crystal of dimensions 210 × 210 × 700 μm of NaNO3 as a model system. A two step simulation procedure is used to obtain the orientation of the quadrupolar tensor information from the experimental spectra and is verified by XRD analysis.

Structural properties of NaAlH4/C nanocomposites were studied using 23Na and 27Al solid-state NMR. The samples were synthesized by melt infiltration of a highly porous carbon support, with typical pore sizes of 2−3 nm. Physical mixtures of high surface carbon with alanates in different stages of hydrogen desorption show somewhat broadened resonances and a small negative chemical shift compared to pure alanates. This is most likely caused by a susceptibility effect of the carbon support material, which shields and distorts the applied magnetic field. After melt infiltration, 23Na and 27Al spectra are broadened with a small downfield average shift, which is mainly caused by a chemical shift distribution and is explained by a larger disorder in the nanoconfined materials and a possible charge transfer to the carbon. Our measurements show that the local structure of the nanoconfined alanate is the similar to bulk alanate because a comparable chemical shift and average quadrupolar coupling constant is found. In contrast to bulk alanates, in partly desorbed nanocomposite samples no Na3AlH6 is detected. Together with a single release peak observed by dehydrogenation experiments, this points toward a desorption in one single step. 23Na spectra of completely desorbed NaAlH4/C and NaH/C nanocomposites confirm the formation of metallic sodium at lower temperatures than those observed for bulk alanates. The structural properties observed with solid-state NMR of the nanoconfined alanate are restored after a rehydrogenation cycle. This demonstrates that the dehydrogenation of the NaAlH4/C nanocomposite is reversible, even without a Ti-based catalyst.

A novel route towards chip integrated NMR analysis is evaluated. The basic element in the design is a stripline RF ‘coil’ which can be defined in a single layer lithographic process and which is fully scalable to smaller dimensions. The sensitivity of such a planar structure can be superior to that of a conventional 3D helix. The basic properties, such as RF field strength, homogeneity and susceptibility broadening are discussed in detail. Secondary effects related to the thermal characteristics are discussed in simplified models. Preliminary NMR tests of basic solid and liquid samples measured at 600 MHz confirm the central findings of the design study. It is concluded that the stripline structure can be a valuable addition to the NMR toolbox; it combines high sensitivity with low susceptibility broadening and high power handling capabilities in a simple scalable design.

Dynamic nuclear polarization in the liquid state was predicted more than 50 years ago by Overhauser. Its application for NMR sensitivity enhancement has been limited because of intrinsic and experimental problems to apply this method at high magnetic fields. Here we report on 95 GHz DNP experiments using the common TEMPO radical dissolved in water. In an efficient non-radiative microwave resonator, we observe average experimental enhancement factors up to −65. The local enhancement in the center of the resonator is calculated to reach a level of −94 at the highest microwave power. At high microwave power, the DNP enhancement shows a linear increase with no tendency to saturation. The results indicate that a substantial sensitivity enhancement is possible for liquid state NMR in nL sample volumes.

Carbazole functionalized polyisocyanides are known to exhibit excellent electronic properties (E. Schwartz, et al., Chemistry of Materials, 2010, 22, 2597). The functionalities and properties of such materials crucially depend on the organization and stability of the polymer structure. We combine solid-state Nuclear Magnetic Resonance (NMR) experiments with first-principles calculations of isotropic chemical shifts, within the recently developed converse approach, to rationalize the origin of isotropic chemical shifts in the crystalline monomer L-isocyanoalanine 2-(9H-carbazol-9-yl) ethyl amide (monomer 1) and thereby gain insight into the structural organization of its polymer (polymer 2). The use of state-of-the-art solid-state NMR experiments combined with Density Functional Theory (DFT) based calculations allows an unambiguous assignment of all proton and carbon resonances of the monomer. We were able to identify the structure stabilising interactions in the crystal and understand the influence of the molecular packing in the crystal structure on the chemical shift data observed in the NMR spectra. Here the Nuclear Independent Chemical Shift (NICS) approach allows discriminating between ‘physical’ interactions amongst neighboring molecules such as ring-current effects and ‘chemical’ interactions such as hydrogen bonding. This analysis reveals that the isocyanide monomer is stabilized by multiple hydrogen bonds such as a bifurcated hydrogen bond involving –N–H, –C–H and OC– moieties and Ar–H⋯CN– hydrogen bonding (Ar = aromatic group). Based on the geometrical arrangement it is postulated that the carbazole units are involved in the weak σ–π interactions giving rise to a Herringbone packing of the molecules. The chemical shift analysis of the polymer spectra readily establishes the existence of N–H⋯OC hydrogen bonds despite the limited resolution exhibited by the polymer spectra. It is also elucidated that the relative arrangement of the carbazole units in the polymer differs significantly from that of the monomer.

To be able to study mass-limited samples and small single crystals, a triple resonance micro-magic angle spinning (μMAS) probehead for the application of high-resolution solid-state NMR of nanoliter samples was developed. Due to its excellent rf performance this allows us to explore the limits of proton NMR resolution in strongly coupled solids. Using homonuclear decoupling we obtain unprecedented 1H linewidths for a single crystal of glycine (Δν(CH2) = 0.14 ppm) at high field (20 T) in a directly detected spectrum. The triple channel design allowed the recording of high-resolution μMAS 13C–15N correlations of [U-13C–15N] arginine HCl and shows that the superior 1H resolution opens the way for high-sensitivity inverse detection of heteronuclei even at moderate spinning speeds and rf-fields. Efficient decoupling leads to long coherence times which can be exploited in many correlation experiments.

An implementation of rotor-synchronised Magic Angle Spinning (MAS) NMR is presented to determine the quadrupolar coupling tensor values from a single crystal study for half-integer quadrupolar nuclei. Using a microcoil based probehead for studying micro crystals with superior sensitivity, we successfully determine the full quadrupolar tensor of 23Na using a micro crystal of dimensions 210 × 210 × 700 μm of NaNO3 as a model system. A two step simulation procedure is used to obtain the orientation of the quadrupolar tensor information from the experimental spectra and is verified by XRD analysis.

In this paper the short and long range order in In0.483Ga0.517P thin films is investigated by solid-state Nuclear Magnetic Resonance (NMR) spectroscopy. To this end two samples were grown on a GaAs substrate by metal–organic vapor phase epitaxy at two different growth-pressures. From band gap energy measurements, CuPt long range order parameters of SCuPt = 0.22 and 0.39 were deduced, respectively. In the 31P spectrum five resonances are observed corresponding to the five possible P(GanIn4−n), n = 0–4, coordinations whose relative intensities correspond to the order in the material, but the intensity variations for order parameters between 0 and 0.5 are minimal. 69Ga, 71Ga and 115In (MQ)MAS spectra were acquired to analyze the quadrupolar and chemical shift distributions related to the (dis)order in these materials in more detail. All these spectra clearly reflect the disorder in the sample and do not show the presence of highly ordered domains. The difference in the order parameter in the sample is not clearly reflected in the spectra. 31P chemical shifts were calculated using Density Functional Theory. The experimentally observed shifts are well reproduced with a simple random model of the disorder, thus confirming the assignment of the resonances. The 31P chemical shifts are very sensitive to changes in the lattice parameter and chemical surroundings. These effects nearly compensate and explain why the 31P chemical shifts in pure InP and GaP are nearly identical whereas a large difference would be expected based on the observed shift difference for the P[In4] and P[Ga4] coordinations in In0.483Ga0.517P.