Visualization and processing of computed solid-state NMR parameters: MagresView and MagresPython

An NMR crystallographic approach, involving the combination of 119Sn NMR spectroscopy, XRD, and DFT calculations, is demonstrated for the characterization of La2Sn2–xTixO7 ceramics. A phase change from pyrochlore (La2Sn2O7) to a layered perovskite phase (La2Ti2O7) is predicted (by radius ratio rules) to occur when x ≈ 0.95. However, the sensitivity of NMR spectroscopy to the local environment is able to reveal a significant two-phase region is present, extending from x = 1.8 to ∼0.2, with limited solid solution at the two extremes, in broad agreement with powder XRD measurements. DFT calculations reveal that there is preferential site substitution of Sn in La2Ti2O7, with calculated shifts for Sn substitution onto Ti1 and Ti2 sites (in the “bulk” perovskite layers) in better agreement with experiment than those for Ti3 and Ti4 (“edge” sites). Substitution onto these two sites also produces structural models with lower relative enthalpy. As the Sn content decreases, there is a further preference for substitution onto Sn2. In contrast, the relative intensities of the spectral resonances suggest that Ti substitution into the pyrochlore phase is random, although only a limited solid solution is observed (up to ∼7% Ti). DFT calculations predict very similar 119Sn shifts for Sn substitution into the two proposed models of La2Ti2O7 (monoclinic (P21) and orthorhombic (Pna21)), indicating it is not possible to distinguish between them. However, the relative energy of the Sn-substituted orthorhombic phase was higher than that of substituted monoclinic cells, suggesting that the latter is the more likely structure.

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“…Computed structures and NMR parameters were processed using Python scripts extending the CCP-NC MagresPython module. 34 …”

Section: Experimental and Computational Methodsmentioning

confidence: 99%

Phase Composition and Disorder in La₂(Sn,Ti)₂O₇ Ceramics: New Insights from NMR Crystallography

et al. 2016

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“… Experimental 1 H DUMBO/MAS NMR spectrum, and the DFT‐predicted 1 H ssNMR spectra of ZBIF‐1, IMIDZB01, and IMIDZB02 visualized and assigned in the MagresView software while employing simple referencing of the DFT data: δ iso =31.2−

σ_{iso}^{cal}

.…”

Section: Resultsmentioning

confidence: 99%

Unexpected Crystallization Patterns of Zinc Boron Imidazolate Framework ZBIF‐1: NMR Crystallography of Integrated Metal–Organic Frameworks

et al. 2017

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Framework materials, that is, metal-organic frameworks (MOFs) and inorganic frameworks (zeolites), are porous systems with regular structures that provide valuable properties suitable for sorption, catalysis, molecular sieving, and so on. Herein, an efficient, experimental/computational strategy is presented that allows detailed characterization of a polycrystalline MOF system, namely, zinc boron imidazolate framework ZBIF-1, with two integrated unit cells on the atomic-resolution level. Although high-resolution H, B, C, and N MAS NMR spectra provide valuable structural information on the coexistence of two distinct asymmetric units in the investigated system, an NMR crystallography approach combining X-ray powder diffraction, solid-state NMR spectroscopy, and DFT calculations allowed the exact structure of the secondary crystalline phase to be firmly defined and, furthermore, the mutual interconnectivity of the two crystalline frameworks to be resolved. Thus, this study shows the versatility and efficiency of solid-state NMR crystallography for the investigation of the wide family of MOF materials with their extensive structural complexity.

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“…The existence of cis/trans isomers is well known for tertiary amides. [17] Upon CUR loading, the lines broaden and overlapping resonances can be observed. This is due to the distribution of environment and the presence of uncoordinated as well as coordinated amide moieties.…”

Section: Figure S2mentioning

confidence: 99%

Loading Dependent Structural Model of Polymeric Micelles by Solid-State NMR

Pöppler

Lübtow²,

Schlauersbach³

et al. 2019

Preprint

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Physically loaded polymeric micelles - from bulk properties to a molecular level understanding: In this work, solid-state NMR complemented by PXRD and quantum chemical calculations is used to learn about the short range order and structural arrangement in polymeric micelles formed by amphiphilic triblock copolymers. From changes in chemical shift and line widths, we could observe that at higher loadings, not just the micellar core but also the hydrophilic corona is involved in coordination of poorly soluble guest molecules, which can explain the poorer dissolution properties. This can serve as a platform for the future, targeted modification of such polymers. <br>

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Visualization and processing of computed solid-state NMR parameters: MagresView and MagresPython

Cited by 64 publications

References 17 publications

Phase Composition and Disorder in La₂(Sn,Ti)₂O₇ Ceramics: New Insights from NMR Crystallography

Phase Composition and Disorder in La₂(Sn,Ti)₂O₇ Ceramics: New Insights from NMR Crystallography

Unexpected Crystallization Patterns of Zinc Boron Imidazolate Framework ZBIF‐1: NMR Crystallography of Integrated Metal–Organic Frameworks

Loading Dependent Structural Model of Polymeric Micelles by Solid-State NMR

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Visualization and processing of computed solid-state NMR parameters: MagresView and MagresPython

Cited by 64 publications

References 17 publications

Phase Composition and Disorder in La2(Sn,Ti)2O7 Ceramics: New Insights from NMR Crystallography

Phase Composition and Disorder in La2(Sn,Ti)2O7 Ceramics: New Insights from NMR Crystallography

Unexpected Crystallization Patterns of Zinc Boron Imidazolate Framework ZBIF‐1: NMR Crystallography of Integrated Metal–Organic Frameworks

Loading Dependent Structural Model of Polymeric Micelles by Solid-State NMR

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Product

Resources

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Phase Composition and Disorder in La₂(Sn,Ti)₂O₇ Ceramics: New Insights from NMR Crystallography

Phase Composition and Disorder in La₂(Sn,Ti)₂O₇ Ceramics: New Insights from NMR Crystallography