Structural disorder and low crystallinity render it challenging to characterise the atomic-level structure of layered double hydroxides (LDH). We report a novel multi-step, first-principles computational workflow for the analysis of paramagnetic solid-state NMR of complex inorganic systems such as LDH, which are commonly used as catalysts and energy storage materials. A series of CO-labelled MgNiAl-LDH, ranging from 0 (MgAl-LDH) to 2 (NiAl-LDH), features three distinct eigenvalues , and of the experimental C chemical shift tensor.
View Article and Find Full Text PDFThe phase purity of a series of ZnAl(OH)SO· nHO layered double hydroxides (ZnAl-LDH) obtained from a reaction of bayerite (Al(OH)) with an excess of zinc(II) sulfate under hydrothermal conditions was investigated as a function of the reaction temperature, the duration of the hydrothermal treatment, and the zinc(II) concentration. The product quality, i.e.
View Article and Find Full Text PDFLayered double hydroxides (LDHs), especially (doped) with transition metals, as well as nanohybrid and 2D materials derived from these structures, are interesting materials due to their catalytic and electrochemical properties. Their reactivity is determined by the atomic level distribution of the transition metal in the LDH cation layer, which is essential to control the design of LDHs with optimized properties. However, low crystallinity, absence of long range order, and/or isoelectronic ions often prevent atomic level structural characterization.
View Article and Find Full Text PDFRecent advances in computational methodology allowed for first-principles calculations of the nuclear shielding tensor for a series of paramagnetic nickel(II) acetylacetonate complexes, [Ni(acac)L] with L = HO, DO, NH, ND, and PMePh have provided detailed insight into the origin of the paramagnetic contributions to the total shift tensor. This was employed for the assignment of the solid-state H and C MAS NMR spectra of these compounds. The two major contributions to the isotropic shifts are by orbital (diamagnetic-like) and contact mechanism.
View Article and Find Full Text PDFBayerite was treated under hydrothermal conditions (120, 130, 140, and 150 °C) to prepare a series of layered double hydroxides (LDHs) with an ideal composition of ZnAl4(OH)12(SO4)0.5·nH2O (ZnAl4-LDHs). These products were investigated by both bulk techniques (powder X-ray diffraction (PXRD), transmission electron microscopy, and elemental analysis) and atomic-level techniques ((1)H and (27)Al solid-state NMR, IR, and Raman spectroscopy) to gain a detailed insight into the structure of ZnAl4-LDHs and sample composition.
View Article and Find Full Text PDFSolid State Nucl Magn Reson
September 2016
Para-amino salicylate (PAS), a tuberculosis drug, was intercalated in three different layered double hydroxides (MgAl, ZnAl, and CaAl-LDH) and the samples were studied by multi-nuclear ((1)H, (13)C, and (27)Al) solid state NMR (SSNMR) spectroscopy in combination with powder X-ray diffraction (PXRD), elemental analysis and IR-spectroscopy to gain insight into the bulk and atomic level structure of these LDHs especially with a view to the purity of the LDH-PAS materials and the concentration of impurities. The intercalations of PAS in MgAl-, ZnAl-, and CaAl-LDH's were confirmed by (13)C SSNMR and PXRD. Moreover, (13)C MAS NMR and infrared spectroscopy show that PAS did not decompose during synthesis.
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