Zeolitic intralayer microchannels of magadiite, a natural layered silicate, to boost green organic synthesis

Ide, Yusuke; Tominaka, Satoshi; Kono, Hiroyuki; Ram, R. N.; Machida, Akihiko; Tsunoji, Nao

doi:10.1039/c8sc03712d

Cited by 34 publications

(51 citation statements)

References 41 publications

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“…Although several natural and many synthetic magadiite samples are available, the structure of magadiite remained hidden until now because of the small crystal size, the complex crystal In the past, several attempts have been made to reveal the crystal structure of magadiite based on unit cell dimensions, chemical composition, NMR, Raman and IR spectra and depending on the comparison with the known structures of seemingly related silicates like Na-RUB-18/octosilicate, kanemite, makatite and dachiardite. Only one structural study, which was published recently, used the whole X-ray powder diffraction pattern of magadiite to establish a structure model using a PDF (pair-distribution function) analysis and real-space methods (Ide et al 2018).…”

Section: Previous Structural Studiesmentioning

confidence: 99%

The crystal structure of mineral magadiite, Na2Si14O28(OH)2∙8H2O

Marler

Krysiak

Grosskreuz

et al. 2022

American Mineralogist

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Magadiite from Lake Magadi was structurally analyzed based on X-ray powder diffraction data. The idealized chemical composition of magadiite is Na16[Si112O224(OH)16]∙64H2O per unit cell. The XRD powder diffraction pattern was indexed in orthorhombic symmetry with lattice parameters a0 = 10.5035(9) Å, b0 = 10.0262(9) Å, and c0 = 61.9608(46) Å. The crystal structure was solved from a synthetic magadiite sample in a complex process using 3D electron diffraction combined with model building as presented in an additional paper. A Rietveld refinement of this structure model performed on a magadiite mineral sample in space group F2dd (No. 43) converged to residual values of RBragg = 0.031 and RF = 0.026 confirming the structure model. Physico-chemical characterization using solid-state NMR spectroscopy, SEM, TG-DTA, and DRIFT spectroscopy further confirmed the structure. The structure of magadiite contains two enantiomorphic silicate layers of, so far, unknown topology. The dense layers exhibit no porosity or micro-channels and have a thickness of 11.5 Å (disregarding the van der Waals radii of the terminal O atoms) and possess a silicon Q4 to Q3 ratio of 2.5. 16 out of 32 terminal silanol groups are protonated, and the remaining groups compensate for the charge of the hydrated sodium cations. Bands of edge-sharing [Na(H2O)6/1.5] octahedra are intercalated between the silicate layers extending along (110) and (110). The water molecules are hydrogen bonded to terminal silanol groups with O···O distances of 2.54–2.91 Å. The structure of magadiite is slightly disordered, typical for hydrous layer silicates (HLS), which possess only weak interactions between neighboring layers. In this respect, the result of the structure refinement represents a somewhat idealized structure. Nevertheless, the natural magadiite possesses a higher degree of structural order than any synthetic magadiite sample. The structure analysis also revealed the presence of strong intra-layer hydrogen bonds between the terminal O atoms (silanol/siloxy groups), confirmed by 1H MAS NMR and DRIFT spectroscopy. The surface zone of the silicate layers, as well as the interlayer region containing the [Na(H2O)6/1.5] octahedra, are closely related to the structure of Na-RUB-18.

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Section: Previous Structural Studiesmentioning

confidence: 99%

The crystal structure of mineral magadiite, Na2Si14O28(OH)2∙8H2O

Marler

Krysiak

Grosskreuz

et al. 2022

American Mineralogist

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“…[ 121 ] Recently, the possible crystal structure of magadiite as one of representative layered silicates has been determined using X‐ray pair distribution functions and synchrotron powder diffractometry. [ 122 ] A combination of diffraction technique, SSNMR and DFT theoretical calculation would provide promising opportunities to extract long‐ and short‐range structural constraints and enable determination of the molecular structure of the layered silicates in the presence of various extents of stacking disorder.…”

Section: Ssnmr Characterization Of Other Microporous Materialsmentioning

confidence: 99%

Recent Advances of Solid‐State NMR Spectroscopy for Microporous Materials

Lafon

Wang

et al. 2020

Advanced Materials

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< 2 nm), such as zeolites, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and porous aromatic frameworks (PAFs), combine high specific surface areas, large pore volumes and shape-selectivity effects, which makes them key materials for a wide range of applications, including catalysis, gas separation/purification, ion exchange, gas storage, and sensing. The diverse framework compositions and functionalities of microporous materials represent a huge challenge for their structural characterization as well as evaluation of their performances. Analytic tools such as X-ray diffraction (XRD), electron microscopy and adsorption-desorption isotherms are now routinely employed for characterization of microporous materials in order to establish the structure-property relationships, and hence, to facilitate the rational design of advanced materials with improved property. However, the structure determination of porous materials using single crystal XRD requires high crystallinity and long-range ordering of the framework. Solid-state NMR (SSNMR) has emerged as a powerful spectroscopic technique with atomic-level resolution, complementary to XRD, in the investigation of structures in Microporous materials have attracted a rapid growth of research interest in materials science and the multidisciplinary area because of their wide applications in catalysis, separation, ion exchange, gas storage, drug release, and sensing. A fundamental understanding of their diverse structures and properties is crucial for rational design of high-performance materials and technological applications in industry. Solid-state NMR (SSNMR), capable of providing atomic-level information on both structure and dynamics, is a powerful tool in the scientific exploration of solid materials. Here, advanced SSNMR instruments and methods for characterization of microporous materials are briefly described. The recent progress of the application of SSNMR for the investigation of microporous materials including zeolites, metal-organic frameworks, covalent organic frameworks, porous aromatic frameworks, and layered materials is discussed with representative work. The versatile SSNMR techniques provide detailed information on the local structure, dynamics, and chemical processes in the confined space of porous materials. The challenges and prospects in SSNMR study of microporous and related materials are discussed.

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“…As for the magadiite and Zn‐magadiite (Figures S1c and 1a‐d), there are no particles found owing to the ionic form in existence. The location of the metal precursor cations are not assured at the present knowledge, and they may be located in the microchannels . After the combustion, the appearance of many black spots proves that these zinc ions have been oxidized to ZnO species, and the layer covered on the top still exists with clear edges.…”

Section: Resultsmentioning

confidence: 82%

Rapid Combustion Synthesis of Metal Oxides Species Highly Dispersed on Layered Silicate Magadiite

et al. 2020

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The good dispersion of metal oxides (MOs) with ultra‐small particles on host materials is essential for improving the utilization efficiency and increasing the service life. Herein, a novel strategy is developed as a methodology to synthesize MOs species highly dispersed on layered silicate magadiite by a rapid combustion method within 30 s. The speediness of the combustion process can avoid the agglomeration of MOs and well‐defined layered structure can further restrict the growth of nanoparticles. Thus, the lamellar structure of magadiite is well‐kept and MOs species with the particle size less than 5 nm immerse on the lamellar platelets. The results demonstrate this process can be considered as a methodology to synthesize different MOs species highly dispersed on various host materials for high efficiency applications.

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Zeolitic intralayer microchannels of magadiite, a natural layered silicate, to boost green organic synthesis

Abstract: We discovered unexpected intralayer microchannels of magadiite, a natural layered silicate, and used it as additive in a TiO2 photocatalytic system oxidizing toluene to realize efficient and selective synthesis of benzoic acid not achieved by conventional photocatalysts.

Cited by 34 publications

References 41 publications

The crystal structure of mineral magadiite, Na2Si14O28(OH)2∙8H2O

The crystal structure of mineral magadiite, Na2Si14O28(OH)2∙8H2O

Recent Advances of Solid‐State NMR Spectroscopy for Microporous Materials

Rapid Combustion Synthesis of Metal Oxides Species Highly Dispersed on Layered Silicate Magadiite

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