Location, Acid Strength, and Mobility of the Acidic Protons in Keggin 12-HPWO: A Combined Solid-State NMR Spectroscopy and DFT Quantum Chemical Calculation Study.
Solid-state C NMR experiments and quantum chemical Density Functional Theory (DFT) calculations of acetone adsorption were used to study the location of protons in anhydrous 12-tungstophosphoric acid (HPW), the mobility of the isolated and hydrated acidic protons, and the acid strength heterogeneity...
| Publicado en: | Journal of the American Chemical Society Vol. 127; no. 51; pp. 18274 - 18281 |
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| Autores principales: | , , , , , , , , |
| Formato: | Artículo |
| Publicado: |
American Chemical Society
12/28/2005
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| Materias: | |
| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=19489531&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 19489531 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 12/28/2005 vid: 127 iid: 51 pid: 997 pub: American Chemical Society artinfo: ui: 19489531 10.1021/ja055925z ppf: 18274 ppct: 7 formats: tig: atl: Location, Acid Strength, and Mobility of the Acidic Protons in Keggin 12-HPWO: A Combined Solid-State NMR Spectroscopy and DFT Quantum Chemical Calculation Study. aug: au: Jun Yang Janik, Michael J. Ding Ma Anmin Zheng Mingjin Zhang Neurock, Matthew Davis, Robert J. Chaohui Ye Feng Deng affil: Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences. University of Virginia. Dalian Institute of Chemical Physics, Chinese Academy of Sciences. su: Protons Nuclear magnetic resonance spectroscopy Density functionals Acetone Adsorption (Chemistry) Hydroxyl group sug: subj: Protons Nuclear magnetic resonance spectroscopy Density functionals Acetone Adsorption (Chemistry) Hydroxyl group ab: Solid-state C NMR experiments and quantum chemical Density Functional Theory (DFT) calculations of acetone adsorption were used to study the location of protons in anhydrous 12-tungstophosphoric acid (HPW), the mobility of the isolated and hydrated acidic protons, and the acid strength heterogeneity of the anhydrous hydroxyl groups. This study presents the first direct NMR experimental evidence that there are two types of isolated protons with different acid strengths in the anhydrous Keggin HPW. Rotational Echo DOuble Resonance (REDOR) NMR experiments combined with quantum chemical DFT calculations demonstrated that acidic protons in anhydrous HPW are localized on both bridging (O) and terminal (O) atoms of the Keggin unit. The CP/MAS NMR experiments revealed that the isolated acidic protons are immobile, but hydrated acidic protons are highly mobile at room temperature. The isotropic chemical shift of the adsorbed acetone suggested that the acid strength of the H(HO) species in partially hydrated HPW is comparable to that of a zeolite, while the acidity of an isolated proton is much stronger than that of a zeolite. Isolated protons on the bridging oxygen atoms of anhydrous HPW are nearly superacidic. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2005 holdings: @attributes: islocal: N |
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