New Methods and Applications in Solid-State NMR Spectroscopy of Quadrupolar Nuclei

Ashbrook, Sharon E.; Sneddon, Scott

doi:10.1021/ja504734p

Cited by 129 publications

(223 citation statements)

References 152 publications

(505 reference statements)

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“…57 coupling constant and asymmetry parameter, respectively) can be determined, as described in the Supporting Information (S10). The approximate values of iso and PQ extracted from the MQMAS NMR spectra are reported in Table 2.…”

Section: Solid-state Nmr Spectroscopymentioning

confidence: 99%

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: Solid-state Nmr Spectroscopymentioning

confidence: 99%

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

et al. 2017

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“…For example, Zn (used in this work) has only one NMR-active isotope ( 67 Zn, I ¼ 5/2) with a relatively low γ and low natural abundance of 4.1% (resulting in a receptivity, relative to 1 H, of 1.18 Â 10 À4 ). Spectral acquisition is further hindered by the presence of a relatively large quadrupole moment (which, coupled with the low γ, produces significant quadrupolar broadening), often necessitating the use of high magnetic fields [19][20][21][22]. Even when resolution is increased through the use of techniques such as MAS, complex and overlapping spectral lineshapes are often still observed in NMR spectra of solids, particularly for disordered materials [23].…”

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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“…SSNMR experiments targeting quadrupolar nuclei are normally challenging and require the use of specialized pulse sequences and experimental techniques. [33][34][35] The nuclear quadrupole moment (Q) couples with ground-state electric field gradients (EFGs) arising from local surroundings such as bound ligands and nearby ions; this anisotropic quadrupolar interaction (QI) acts as a significant perturbation on the fundamental Zeeman interaction in SSNMR experiments. 27 Al has a moderate Q of 146.6(10) mb.…”

Section: Introductionmentioning

confidence: 99%

Investigating adsorption of organic compounds in metal-organic framework MIL-53

Ibrahim

et al. 2015

Can. J. Chem.

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Metal-organic frameworks (MOFs) are versatile materials that incorporate metal centers along with organic linkers in highly ordered, intricate structures. MIL-53 is a MOF that exhibits a "breathing effect," where the pore size and MOF topology are profoundly influenced by the identity and binding mechanism of guest molecules. This phenomenon renders MIL-53 a promising candidate for sensing applications. In this report, the adsorption of various organic compounds within MIL-53 is investigated using a combination of complementary techniques. Thermal gravimetric analysis experiments confirm loading of the guest molecules and yield insight into adsorption interactions and strengths. Significant guest-induced changes in the crystal structure of MIL-53 are revealed by powder X-ray diffraction experiments; specific unique phases of MIL-53 are related to the identity of the guest molecule and its binding mechanism to the framework. 27 Al and 13 C solid-state NMR experiments probe the interaction between guest molecules and MIL-53. The relationship between the nature of the guest, the structure of MIL-53, and 27 Al NMR parameters is explored. 27 Al NMR parameters are sensitive to the host-guest binding mechanism (i.e., hydrogenbonding or -stacking interactions) and yield valuable information regarding the influence of the adsorbates on the local aluminum environment. This combination of physical characterization techniques is a useful probe of guest adsorption and the breathing effect within MIL-53 and should prove useful for investigation of related MOFs. Résumé: Les réseaux métallo-organiques (MOF, acronyme anglais pour Metal-Organic Frameworks) sont des matériaux polyvalents où des centres métalliques sont incorporés dans un réseau organique formant des structures complexes et hautement ordonnées. Le MIL-53 est un réseau métallo-organique présentant un « effet de respiration », dont la taille des pores et la topologie du réseau métallo-organique dépendent fortement de l'identité et du mécanisme de liaison des molécules invitées. Ce phénomène fait du MIL-53 un candidat prometteur pour des applications dans le domaine des capteurs. Dans les présents travaux, nous avons étudié l'adsorption de divers composés organiques au MIL-53 à l'aide d'un ensemble de techniques complémentaires. Des analyses thermogravimétriques confirment la charge de molécules invitées et fournissent un aperçu des interactions et des forces d'adsorption. Des expériences de diffraction des rayons X sur poudre ont permis de révéler des modifications importantes de la structure cristalline du MIL-53 induites par l'invité; des phases uniques propres au MIL-53 sont liées à l'identité de l'invité et à son mécanisme de liaison au réseau. Des expériences de RMN 27 Al et 13 C à l'état solide ont permis d'explorer les interactions entre les molécules invitées et le MIL-53. Nous avons étudié la relation entre la nature de l'invité, la structure du MIL-53 et les paramètres RMN 27 Al. Ces derniers sont sensibles au mécanisme de liaison hôte-invité (c.-à -d. les l...

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New Methods and Applications in Solid-State NMR Spectroscopy of Quadrupolar Nuclei

Cited by 129 publications

References 152 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

Investigating adsorption of organic compounds in metal-organic framework MIL-53

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