Assembly of a Homochiral, Body-Centered Cubic Network Composed of Vertex-Shared Mg12 Cages:  Use of Electrospray Ionization Mass Spectrometry to Monitor Metal Carboxylate Nucleation

Jeffrey A. Rood, William C. Boggess, Bruce C. Noll, and Kenneth W. Henderson*
Contribution from the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670
J. Am. Chem. Soc., 2007, 129 (44), pp 13675–13682
DOI: 10.1021/ja074558j
Publication Date (Web): October 10, 2007
Copyright © 2007 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, khenders@nd.edu

Abstract

Abstract Image

Reaction of Mg(NO3)2·6H2O with (+)-camphoric acid (H2cam) in acetonitrile results in the immediate formation of soluble, dimetallic [Mg2(Hcam)3]+ cations. The formation of these stable cations in solution was determined by electrospray ionization mass spectrometry (ESI−MS). These dimers are 3-fold paddle-wheels, which associate together through the neutral acid units to build the metal-organic framework [Mg2(Hcam)3·3H2O]·NO3·MeCN, 1. The network consists of a series of fused Mg12 cages that have 12 water molecules at their centers, creating isolated 0D cavities within the structure. Overall, the extended structure of 1 is a body-centered cubic (bcu) lattice, with the Mg12 cages being utilized as eight-connected nodes. The framework of 1 is chiral and adopts the very unusual space group I23. Use of 1,3-propanediol as an additive results in the formation of the simple 1D polymer [Mg(cam){HO(CH2)3OH}2], 2. In 2, each carboxylate-bridged metal center is chelated by two diols. ESI−MS studies confirm the formation of new ions in these solutions. The identities of 1 and 2 were confirmed by a combination of single-crystal X-ray diffraction, elemental analyses, IR, NMR, themogravimetric analyses, and ESI−MS data. ESI−MS has proven to be a valuable technique in the identification of stable SBUs in solution prior to network formation.

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  • Published In Issue November 07, 2007
  • Received June 21, 2007

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