Recent Advances of Solid‐State NMR Spectroscopy for Microporous Materials

Abstract

< 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.

25 Jahre retikuläre Chemie

“…In der Tatb esetzen diffuse Streuungen, die zwischen den Bragg-Positionen verteilt sind, immer die Beugungsmuster von MOFs und COFs.D ie Verwendung dieser Streukomponente aus PXRD-Daten wurde genutzt, um die radiale Verteilung aller Atom-Atom-Korrelationen, bekannt als Paarverteilungsfunktion (PDF,p air distribution function), abzuleiten, anhand derer lokale Strukturmodelle verfeinert werden kçnnen. [155] Eine wichtige Rolle spielen schließlich auch Spektroskopien wie SSNMR und Rçntgenabsorptionsspektroskopie (XAS,X -ray absorption spectroscopy), [156] die eine vorteilhafte Isolierung der atomaren Spezies ermçglichen, von denen die detektierten Signale stammen. Es ist erwähnenswert, dass diese Te chniken besonders bei der Erforschung amorpher und glasartiger Gerüste von entscheidender Bedeutung sind, da ihr Mangel an langreichweitiger Periodizitätdie lokale Struktur zu ihrem wichtigsten kristallographischenA spekt macht.…”

Surface acidity of tin dioxide nanomaterials revealed with 31P solid-state NMR spectroscopy and DFT calculations

“…Solid-state nuclear magnetic resonance (NMR) spectroscopy is a powerful method with which to study detailed local structure and properties of solids. [14][15][16][17][18][19][20][21] Combined with appropriate probe molecules such as trimethylphosphine (TMP), the smallest alkyl phosphine that can be bound the acid sites of oxide surfaces, solid-state NMR data can provide rich information on the location, type, strength as well as concentration of acid sites. [22][23][24] This approach has been extensively used to study metal oxide based catalysts and porous catalytic materials, such as zeolites and mesoporous materials.…”

A Zeolite‐confined Pd/Acid Sites for High Efficiency of B−H Cleavage

“…MAS NMR, with the ability to provide the spatial proximity/interaction in the local structure, [24–26] is further applied to gain deep insight into the interaction between acid sites of zeolite and Pd. The autocorrelation peaks at (1.2, 2.4) ppm, (2.6, 5.2) ppm and (3.7, 7.4) ppm in 2D 1 H DQ‐SQ MAS NMR of Pd@ZSM‐5 (Figure 3b) reveals the spatial proximity of terminal Si‐OH protons, terminal Al‐OH protons and Brønsted acid sites, respectively [22,27–30] . A strong autocorrelation peak at (7.1, 14.2) ppm is attributed to the strong interaction between the trapped water molecules in the framework and Lewis acid sites [31] .…”