Superacids, defined as acids with a Hammett acidity function H0 ≤ -12, are useful materials, but a need exists for new, designable solid state systems. Here, we report superacidity in a sulfated metal-organic framework (MOF) obtained by treating the microcrystalline form of MOF-808 [MOF-808-P: Zr6O5(OH)3(BTC)2(HCOO)5(H2O)2, BTC = 1,3,5-benzenetricarboxylate] with aqueous sulfuric acid to generate its sulfated analogue, MOF-808-2.5SO4 [Zr6O5(OH)3(BTC)2(SO4)2.5(H2O)2.5]. This material has a Hammett acidity function H0 ≤ -14.5 and is thus identified as a superacid, providing the first evidence for superacidity in MOFs. The superacidity is attributed to the presence of zirconium-bound sulfate groups structurally characterized using single-crystal X-ray diffraction analysis.
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Angew Chem Int Ed Engl
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Department of chemistry, University of California, Riverside, Riverside, CA, 92521, USA.
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RSC Adv
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Centro de Investigaciones Científicas, Instituto de Química Aplicada, Universidad del Papaloapan Tuxtepec Oaxaca 68301 Mexico
The use of homogeneous Brønsted acid cocatalysts (such as benzoic acid) in hydroacylation reactions imine intermediates has been extensively studied. However, the use of heterogeneous cocatalysts has been limited to montmorillonite K10. Thus, we can use other solid acids to increase the efficiency of the reaction.
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Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States.
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View Article and Find Full Text PDFACS Omega
March 2024
Qingyang Chemical Industry Corporation, Liaoyang 111000, China.
The nitration reaction of aromatic compounds is one of the extensively studied chemical reactions that result in the manufacturing of various industrial products applied in pharmaceuticals, dyes, perfumes, and explosives. A series of modified sulfated zirconia (SZ) catalysts SO/ZrO-MO (M=Ce, Co, Mn, Zn, and M/SZ) doped with different metal elements by a coprecipitation method were investigated in the toluene nitration reaction. Various characterization techniques (X-ray diffraction, Brunauer-Emmett-Teller, thermogravimetric analysis, X-ray photoelectron spectroscopy, and temperature-programmed desorption of ammonia) indicated that doping metal elements in SZ led to excellent catalytic properties, increasing the specific surface area of the catalyst and facilitating the formation of a stable tetragonal zirconia phase.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2023
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL-60208-3113, USA.
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