Combining solid-state NMR spectroscopy with first-principles calculations – a guide to NMR crystallography

Ashbrook, Sharon E.; McKay, David

doi:10.1039/c6cc02542k

Cited by 224 publications

(309 citation statements)

References 136 publications

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“…One crucial requirement for the prediction of accurate NMR parameters from a given structure is that the structure itself must represent a realistic minimum on the energy landscape. 17,47,49,50 In order to ensure this is the case, the atomic coordinates and, often, unit cell parameters can (or, indeed, must) be optimised to an energy minimum. Sneddon et al 50 recently investigated the computational parameters most suited to the optimisation of AlPOs and showed that the optimisation of all atomic coordinates and unit cell parameters with the inclusion of semi-empirical dispersion correction schemes yielded results in good agreement with both crystallographic and spectroscopic measurements, without applying any a priori constraints to the structural model.…”

Section: Dft Calculationsmentioning

confidence: 99%

“…11,17-19, [46][47][48][49] As most of the forms of as-made AlPO-34 considered here have crystal structures refined with disorder of the SDA (emim and cyclam), 29,30,34 water (pyr) 31 or both (pip), 32 DFT calculations were used to help interpret and assign the experimental NMR spectra. One crucial requirement for the prediction of accurate NMR parameters from a given structure is that the structure itself must represent a realistic minimum on the energy landscape.…”

Section: Dft Calculationsmentioning

confidence: 99%

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A Multinuclear NMR Study of Six Forms of AlPO-34: Structure and Motional Broadening

et al. 2017

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We report a study of the CHA-type aluminophosphate AlPO-34, prepared with six different structure-directing agents (SDAs): piperidine (pip), morpholine (mor), pyridine (pyr), 1,4,8,11-tetraazacyclotetradecane (cyclam), 1,3-dimethylimidazolium (dmim) chloride and 1-ethyl-3-methylimidazolium (emim) bromide. Using a combination of solidstate NMR spectroscopy, periodic density functional theory (DFT) calculations and synchrotron X-ray diffraction, we show that, even in crystallographically well-ordered materials such as AlPO-34 with dmim as the SDA, local disorder may be present. For such disordered structures, where it is challenging to use DFT to assign NMR spectra, we show that the 31 P isotropic chemical shift can be predicted accurately using the mean P-O bond length and P-O-Al bond angle, in an extension of previous work. Variable-temperature 27 Al NMR reveals the presence of microsecond-timescale dynamics in all forms of AlPO-34, with two different motional regimes observed, depending on whether structural H2O is also present. H2O is detected in AlPO-34 prepared with mor as the SDA, although this material was previously reported as anhydrous, suggesting that this form of AlPO-34 may be hygroscopic despite the presence of the SDAs within the pores.

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Section: Dft Calculationsmentioning

confidence: 99%

Section: Dft Calculationsmentioning

confidence: 99%

A Multinuclear NMR Study of Six Forms of AlPO-34: Structure and Motional Broadening

et al. 2017

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“…Note that the numbering scheme used for pur is not that typically used in organic chemistry, but has been chosen to facilitate comparison with other linkers. [11] GME nIm þ nbIm YOZBIZ assignment of spectra [24,25]. While extremely valuable in many cases, this can prove challenging if there are a large number of distinct atoms in the unit cell (as is the case for many ZIFs) or if there is significant disorder and/or dynamics of the linkers, functional groups or incorporated solvent/guest molecules.…”

Section: Introductionmentioning

confidence: 99%

Investigation of zeolitic imidazolate frameworks using 13 C and 15 N solid-state NMR spectroscopy

Sneddon

Kahr

Orsi

et al. 2017

Solid State Nuclear Magnetic Resonance

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Zeolitic imidazolate frameworks (ZIFs) are a subclass of metal-organic frameworks (MOFs) with extended threedimensional networks of transition metal nodes (bridged by rigid imidazolate linkers), with potential applications in gas storage and separation, sensing and controlled delivery of drug molecules. Here, we investigate the use of 13 C and 15 N solid-state NMR spectroscopy to characterise the local structure and disorder in a variety of singleand dual-linker ZIFs. In most cases, a combination of a basic knowledge of chemical shifts typically observed in solution-state NMR spectroscopy and the use of dipolar dephasing NMR experiments to reveal information about quaternary carbon species are combined to enable spectral assignment. Accurate measurement of the anisotropic components of the chemical shift provided additional information to characterise the local environment and the possibility of trying to understand the relationships between NMR parameters and both local and long-range structure. First-principles calculations on some of the simpler, ordered ZIFs were possible, and provided support for the spectral assignments, while comparison of these model systems to more disordered ZIFs aided interpretation of the more complex spectra obtained. It is shown that 13 C and 15 N NMR are sufficiently sensitive to detect small changes in the local environment, e.g., functionalisation of the linker, crystallographic inequivalence and changes to the framework topology, while the relative proportion of each linker present can be obtained by comparing relative intensities of resonances corresponding to chemically-similar species in cross polarisation experiments with short contact times. Therefore, multinuclear NMR spectroscopy, and in particular the measurement of both isotropic and anisotropic parameters, offers a useful tool for the structural study of ordered and, in particular, disordered ZIFs.

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“…44 The wide applications of PAW-based calculations to "NMR crystallography" are well documented. [45][46][47] The PAW methodology has been used several times for the calculation of chlorine NMR parameters. 21, 24-25, 28-29, 48 However, the performance for the prediction of EFG tensor parameters for ionic systems is low relative to covalent systems.…”

Section: Introductionmentioning

confidence: 99%

Exploring Systematic Discrepancies in DFT Calculations of Chlorine Nuclear Quadrupole Couplings

et al. 2017

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Citation for published item:ohD ynd § rej nd rodgkinsonD ul nd iddi(eldD gory wF nd tesD tonthn F nd hr § ¡ %nsk¡ yD wrtin @PHIUA 9ixploring systemti disrepnies in hp lultions of hlorine nuler qudrupole ouplingsF9D tournl of physil hemistry eFD IPI @PIAF ppF RIHQERIIQF Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACT: Previous studies revealed significant discrepancies between DFT-calculated and experimental nuclear quadrupolar coupling constants (C Q ) at chlorine atoms, particularly in ionic solids. Various aspects of the computations are systematically investigated here, including the choice of the DFT functional, basis set convergence, and geometry optimization protocol. The effect of fast (fs) time-scale dynamics are probed using molecular dynamics (MD) and nuclear quantum effects (NQEs) are considered using path-integral MD calculations. It is shown that the functional choice is the most important factor related to improving the accuracy of the 2 quadrupolar coupling calculations and functionals beyond the generalized gradient approximation (GGA) level, such as hybrid and meta-GGA functionals, are required for good correlations with experiment. The influence of molecular dynamics and NQEs is less important than the functional choice in the studied systems. A method which involves scaling the calculated quadrupolar coupling constant is proposed here; its application leads to good agreement with experimental data.

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Combining solid-state NMR spectroscopy with first-principles calculations – a guide to NMR crystallography

Cited by 224 publications

References 136 publications

A Multinuclear NMR Study of Six Forms of AlPO-34: Structure and Motional Broadening

A Multinuclear NMR Study of Six Forms of AlPO-34: Structure and Motional Broadening

Investigation of zeolitic imidazolate frameworks using 13 C and 15 N solid-state NMR spectroscopy

Exploring Systematic Discrepancies in DFT Calculations of Chlorine Nuclear Quadrupole Couplings

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