Author
Gerhard Fink
Other affiliations: Institut Universitaire de France, Versailles Saint-Quentin-en-Yvelines University
Bio: Gerhard Fink is an academic researcher from Centre national de la recherche scientifique. The author has contributed to research in topics: Carboxylate & Chemical shift. The author has an hindex of 8, co-authored 10 publications receiving 1725 citations. Previous affiliations of Gerhard Fink include Institut Universitaire de France & Versailles Saint-Quentin-en-Yvelines University.
Papers
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TL;DR: Analysis of the hydration process by solid-state NMR has clearly indicated that the trapped water molecules interact with the carboxylate groups through hydrogen bonds, but do not affect the hydroxyl species bridging the aluminum atoms.
Abstract: Aluminum 1,4-benzenedicarboxylate Al(OH)[O2CC6H4CO2]⋅ [HO2CC6H4CO2H]0.70 or MIL-53 as (Al) has been hydrothermally synthesized by heating a mixture of aluminum nitrate, 1,4-benzenedicarboxylic acid, and water, for three days at 220 °C. Its 3 D framework is built up of infinite trans chains of corner-sharing AlO4(OH)2 octahedra. The chains are interconnected by the 1,4-benzenedicarboxylate groups, creating 1 D rhombic-shaped tunnels. Disordered 1,4-benzenedicarboxylic acid molecules are trapped inside these tunnels. Their evacuation upon heating, between 275 and 420 °C, leads to a nanoporous open-framework (MIL-53 ht (Al) or Al(OH)[O2CC6H4CO2]) with empty pores of diameter 8.5 A. This solid exhibits a Langmuir surface area of 1590(1) m2 g−1 together with a remarkable thermal stability, since it starts to decompose only at 500 °C. At room temperature, the solid reversibly absorbs water in its tunnels, causing a very large breathing effect and shrinkage of the pores. Analysis of the hydration process by solid-state NMR (1H, 13C, 27Al) has clearly indicated that the trapped water molecules interact with the carboxylate groups through hydrogen bonds, but do not affect the hydroxyl species bridging the aluminum atoms. The hydrogen bonds between water and the oxygen atoms of the framework are responsible for the contraction of the rhombic channels. The structures of the three forms have been determined by means of powder X-ray diffraction analysis. Crystal data for MIL-53 as (Al) are as follows: orthorhombic system, Pnma (no. 62), a = 17.129(2), b = 6.628(1), c = 12.182(1) A; for MIL-53 ht (Al), orthorhombic system, Imma (no. 74), a = 6.608(1), b = 16.675(3), c = 12.813(2) A; for MIL-53 lt (Al), monoclinic system, Cc (no. 9), a = 19.513(2), b = 7.612(1), c = 6.576(1) A, β = 104.24(1)°.
1,737 citations
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TL;DR: A central-transition-selective pi pulse at the beginning of the t1 evolution period differentiates coherence transfer pathways of double-quantum coherences arising from coupled spins and from a single spin, so that the latter can be efficiently filtered out by phase cycling.
Abstract: A double-quantum homonuclear correlation nuclear magnetic resonance experiment for dipolar-coupled half-integer quadrupolar nuclei in solids is presented. The experiment is based on rotary resonance dipolar recoupling and uses bracketed spin-lock pulses to excite double-quantum coherence and later to convert it to the zero-quantum one. A central-transition-selective π pulse at the beginning of the t1 evolution period differentiates coherence transfer pathways of double-quantum coherences arising from coupled spins and from a single spin, so that the latter can be efficiently filtered out by phase cycling. The experiment was tested on an aluminophosphate molecular sieve AlPO4-14, a material with a variety of aluminum quadrupolar coupling constants, isotropic chemical shifts and homonuclear distances. In a two-dimensional spectrum aluminum dipolar couplings with internuclear distances between 2.9 and 5.5 A were resolved. Although the experiment requires an application of weak radio-frequency fields, frequency offsets did not affect its performance crucially.
86 citations
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TL;DR: In this paper, two gallium carboxylates of MOF-type have been synthesized by using 1,2,4,5-benzenetetracarboxylate (Ga4(OH)8[C10O8H2]·5−5.6H2O or MIL-120) or 1, 2, 4, 5 -benzenetricarboxylic acid (MIL-124) as linkers.
Abstract: Two gallium carboxylates of MOF-type have been hydrothermally synthesized (210 °C) by using 1,2,4,5-benzenetetracarboxylate (Ga4(OH)8[C10O8H2]·5−5.6H2O or MIL-120) or 1,2,4-benzenetricarboxylate (Ga2(OH)4[C9O6H4] or MIL-124) as linkers. The structures of both compounds solved from XRD analysis, revealed two independent crystallographic sites for the gallium atoms, which are connected to each other through μ2-hydroxo edge, generating zigzag chains with a cis−trans mode. The inorganic ribbons are linked to each other via all the carboxylate functions of the pyromellitate ligand to form a 3D framework (MIL-120) or two of the carboxylate arms of the trimellitate ligand to form a 2D structure (MIL-124). For the latter, one of the carboxylate arms is not bonded to the gallium centers, resulting in the layered aspect of the final structure. Solid-state NMR using the slow-CTMAS method has been successfully implemented for the determination of the gallium site parameters for MIL-120, allowing more resolved spectra...
50 citations
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TL;DR: The sensitivity, advantages and drawbacks of DQF-STMAS are compared to 3QMAS and the soft-pulse added mixing (SPAM) idea is introduced, resulting in a net sensitivity gain with respect to 2D NMR methods.
21 citations
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TL;DR: The application of the flip-back increases significantly the relative signal intensity of the component with the longer T(1), making this component detectable even after using short recycle delays, and could be used routinely to get (13)C CPMAS NMR spectra of mixtures in constant experimental time and signal-to-noise ratio.
17 citations
Cited by
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5,393 citations
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TL;DR: Kenji Sumida, David L. Rogow, Jarad A. Mason, Thomas M. McDonald, Eric D. Bloch, Zoey R. Herm, Tae-Hyun Bae, Jeffrey R. Long
Abstract: Kenji Sumida, David L. Rogow, Jarad A. Mason, Thomas M. McDonald, Eric D. Bloch, Zoey R. Herm, Tae-Hyun Bae, Jeffrey R. Long
5,389 citations
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TL;DR: The state-of-the-art on hybrid porous solids, their advantages, their new routes of synthesis, the structural concepts useful for their 'design', aiming at reaching very large pores are presented.
Abstract: This critical review will be of interest to the experts in porous solids (including catalysis), but also solid state chemists and physicists. It presents the state-of-the-art on hybrid porous solids, their advantages, their new routes of synthesis, the structural concepts useful for their ‘design’, aiming at reaching very large pores. Their dynamic properties and the possibility of predicting their structure are described. The large tunability of the pore size leads to unprecedented properties and applications. They concern adsorption of species, storage and delivery and the physical properties of the dense phases. (323 references)
5,187 citations
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TL;DR: The Zr-MOFs presented in this work have the toughness needed for industrial applications; decomposition temperature above 500 degrees C and resistance to most chemicals, and they remain crystalline even after exposure to 10 tons/cm2 of external pressure.
Abstract: Porous crystals are strategic materials with industrial applications within petrochemistry, catalysis, gas storage, and selective separation Their unique properties are based on the molecular-scale porous character However, a principal limitation of zeolites and similar oxide-based materials is the relatively small size of the pores, typically in the range of medium-sized molecules, limiting their use in pharmaceutical and fine chemical applications Metal organic frameworks (MOFs) provided a breakthrough in this respect New MOFs appear at a high and an increasing pace, but the appearances of new, stable inorganic building bricks are rare Here we present a new zirconium-based inorganic building brick that allows the synthesis of very high surface area MOFs with unprecedented stability The high stability is based on the combination of strong Zr−O bonds and the ability of the inner Zr6-cluster to rearrange reversibly upon removal or addition of μ3-OH groups, without any changes in the connecting carbox
4,958 citations