Ionothermal O-17 enrichment of oxides using microlitre quantities of labelled water

Griffin, John M. and Clark, Lucy and Seymour, Valerie R. and Aldous, David W. and Dawson, Daniel M. and Iuga, Dinu and Morris, Russell E. and Ashbrook, Sharon E. (2012) Ionothermal O-17 enrichment of oxides using microlitre quantities of labelled water. Chemical Science, 3 (7). pp. 2293-2300. ISSN 2041-6520

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Abstract

We present an ionothermal-based method for the simple and low-cost enrichment in O-17 of oxide materials. This is demonstrated for the case of SIZ-4, an ionothermally-prepared aluminophosphate framework with the CHA topology. A preliminary study of unenriched samples of SIZ-4 highlights the importance of the careful choice of template in order to obtain an ordered structure. We then show how an ionothermal synthesis procedure incorporating microlitre quantities of O-17-enriched H2O enables as-prepared and calcined samples of SIZ-4 to be obtained with O-17 enrichment levels that are sufficient to enable the recording of high-quality O-17 solid-state NMR spectra. While second-order quadrupolar-broadened resonances are unresolved in O-17 MAS NMR spectra, O-17 double-rotation (DOR) and multiple-quantum (MQ) MAS NMR spectra reveal distinct resonances that are partially assigned by comparison with NMR parameters derived using first-principles calculations. The calculations also enable an investigation of the dependence of O-17 NMR parameters on the local structural environment. We find that both the O-17 isotropic chemical shift and quadrupolar coupling constant show clear dependencies on Al-O-P bond lengths, and angles and will therefore provide a sensitive probe of structure and geometry in aluminophosphate frameworks in future studies.

Item Type:
Journal Article
Journal or Publication Title:
Chemical Science
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1600
Subjects:
ID Code:
75691
Deposited By:
Deposited On:
28 Sep 2015 11:05
Refereed?:
Yes
Published?:
Published
Last Modified:
01 May 2020 03:39