Xie, Dan and McCusker, Lynne B. and Baerlocher, Christian and Gibson, Lisa and Burton, Allen W. and Hwang, Son-Jong (2009) Optimized Synthesis and Structural Characterization of the Borosilicate MCM-70. Journal of Physical Chemistry C, 113 (22). pp. 9845-9850. ISSN 1932-7447 http://resolver.caltech.edu/CaltechAUTHORS:20090901-111941361
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A structure analysis of the borosilicate zeolite MCM-70, whose synthesis had been patented in 2003, was reported in 2005. Unfortunately, that structure analysis was somewhat ambiguous. Anisotropic line broadening made it difficult to model the peak shape, some peaks in the electron density map could not be interpreted satisfactorily, the framework geometry was distorted, and MAS NMR results were partially contradictory. In an attempt to resolve some of these points, an optimization of the synthesis was undertaken, and the structure was reinvestigated. The structure was solved from synchrotron powder diffraction data collected on an as-synthesized sample (Pmn2_1, a = 13.3167(1) Å, b = 4.6604(1) Å, c = 8.7000(1) Å) using a powder charge-flipping algorithm. The framework topology, with a 1-dimensional, 10-ring channel system, is identical to the one previously reported. However, the B in this new sample was found to be ordered in the framework, fully occupying one of the four tetrahedral sites. Two extra-framework K^+ ion positions, each coordinated to five framework O atoms and one water molecule, were also found. The solid state ^(29)Si, ^(11)B and ^1H NMR results are fully consistent with this ordered structure.
|Additional Information:||Copyright © 2009 American Chemical Society. Received: April 16, 2009; Revised Manuscript Received: April 24, 2009. Publication Date (Web): May 8, 2009. We thank the beamline scientists at the SNBL at the ESRF in Grenoble, France, for their assistance with the powder diffraction measurements. The NMR facility at Caltech was supported by the National Science Foundation (NSF) under Grant No. 9724240 and supported in part by the MRSEC Program of the NSF under Award No. DMR-0520565. This work was funded in part by the Swiss National Science Foundation. Supporting Information: Crystallographic information file for MCM-70 (CIF). This material is available free of charge via the Internet at http://pubs.acs.org.|
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|Deposited By:||George Porter|
|Deposited On:||09 Sep 2009 18:38|
|Last Modified:||26 Dec 2012 11:18|
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