High-Resolution Structural Characterization of Two Layered Aluminophosphates by Synchrotron Powder Diffraction and NMR Crystallographies

Abstract

MATERIAUX+ATUThe syntheses and structure resolution process of two highly complex powdered aluminophosphates with an original 5:7 Al/P ratio are presented: [Al-5(OH)(PO4)(3)(PO3OH)(4)] [NH3(CH2)(2)NH3](2) [2H(2)O], compound 1, and [Al-5(PO4)(5)(PO3OH)(2)] [NH3(CH2)(3)NH3](2) [H2O], compound 2. We have previously reported the structure of the periodic part of 1 by coupling synchrotron powder diffraction and solid-state nuclear magnetic resonance (NMR) crystallographies. With a similar strategy, that is, input of large parts of the building blocksdetermined by analysis of the Al-27-P-31 correlation pattern of the two-dimensional (2D) NMR spectrum in the structure search process, we first determine the periodic structure of 2, using the powder synchrotron diffraction data as cost function. Both 1 and 2 are layered materials, in which the inorganic layers contain five P and seven Alinequivalent atoms, with aluminum atoms that are found in three different coordination states, AlO4, AlO5, and AlO6, and the interlayer space contains the amines and water molecules. In 1, the inorganic layers are stacked on each other with a 42 element of symmetry along the c-axis, while they are stacked with a 180 degrees rotation angle in 2. By analysis of a set of high-resolution 1D and 2D NMR spectra (P-31, Al-27, H-1, N-15, C-13, Al-27-P-31, H-1-P-31, and H-1-N-14) the structure analysis of 1 and 2 is extended beyond the strict periodicity, to which diffraction is restricted, and provides localization of the hydroxyl groups and water molecules in the frameworks and an attempt to correlate the presence of these latter species to the structural features of the two samples is presented. Finally, the dehydration/rehydration processes occurring in these solids are analyzed. The methodology of the structure determination for these dehydrated forms uses the same principles, combining X-ray powder diffraction and solid-state NMR data

New Stories of Zeolite Structures: Their Descriptions, Determinations, Predictions, and Evaluations

“…However, solid-state NMR is worthy of particular attention. − Recent studies have shown that it is possible to determine the structures of organic crystals using solid-state NMR data, which is known as NMR crystallography. − For zeolites and related open-framework compounds, NMR crystallography has also shown some promising applications. As a matter of fact, provided that the cell parameters and the space group are given, solid-state NMR data are able not only to determine but also to refine the framework structures of zeolites. ,− A very recent report even showed the possibility of zeolite structure determination by NMR crystallography without knowing its space group . PDF analysis of PXRD data is another emerging opportunity for zeolite structure determination. − The most essential advantage of NMR or PDF technique is their less dependence on long-range crystallinity, making them more suitable than conventional XRD methods when highly crystalline samples are not available.…”

NMR crystallography: structure and properties of materials from solid-state nuclear magnetic resonance observables

“…Taulelle and coworkers have also made substantial contributions, in particular to the NMR crystallography of layered materials and nanoporous materials (Taulelle et al, 2013). Two valuable recent examples include the characterization of layered aluminophosphates by synchrotron powder diffraction and NMR crystallography (Bouchevreau et al, 2013a) and further related work on such materials (Bouchevreau et al, 2013b). Dawson et al (2017a) have recently described a modification to the published structure of the aluminophosphate AlPO-53(A) on the basis of NMR crystallographic methods, including DFT modeling of various candidate structures.…”

A Phosphosilicate Compound, NaCa3PSiO8: Structure Solution and Luminescence Properties

“…Materials with certain particular frameworks are often channelized toward specific applications, based on the understandings then; however, these materials may also offer a considerable number of topologies and are finding new applications that were considered unviable a few decades ago. , Among the most prominent and well-understood materials that form such frameworks are aluminosilicates . Certain other frameworks, such as aluminophosphates, gallophosphates, gallosilicates, and phosphosilicates, are also extensively used in specific applications. , Although most of these classes of compounds are natural in origin, specific applications based on these materials have only recently been developed, because of limitations in understanding their precise chemical and structural details.…”

“…5 Certain other frameworks, such as aluminophosphates, gallophosphates, gallosilicates, and phosphosilicates, are also extensively used in specific applications. 6,7 Although most of these classes of compounds are natural in origin, specific applications based on these materials have only recently been developed, because of limitations in understanding their precise chemical and structural details.…”