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RISS 인기검색어
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- 저자 : ( E. J. Cording ) (검색결과 3 건)
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Polyporous Metal-Coordination Frameworks
Gassensmith, Jeremiah J.,Smaldone, Ronald A.,Forgan, Ross S.,Wilmer, Christopher E.,Cordes, David B.,Botros, Youssry Y.,Slawin, Alexandra M. Z.,Snurr, Randall Q.,Stoddart, J. Fraser American Chemical Society 2012 ORGANIC LETTERS Vol.14 No.6
<P>Starting from a chiral building block?α-cyclodextrin?and rubidium salts, the crystallization of a complex of chiral helices, which constitute a “green” porous coordination polymer, has been realized. Cyclodextrin molecules coordinated by rubidium ions form porous, infinitely long left-handed helical channels, interdigitated with each other. A theoretical examination of the potential of this new material to act as a medium for chiral separation is presented.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/orlef7/2012/orlef7.2012.14.issue-6/ol300199a/production/images/medium/ol-2012-00199a_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ol300199a'>ACS Electronic Supporting Info</A></P>
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Nanoporous Carbohydrate Metal–Organic Frameworks
Forgan, Ross S.,Smaldone, Ronald A.,Gassensmith, Jeremiah J.,Furukawa, Hiroyasu,Cordes, David B.,Li, Qiaowei,Wilmer, Christopher E.,Botros, Youssry Y.,Snurr, Randall Q.,Slawin, Alexandra M. Z.,Stoddar American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.1
<P>The binding of alkali and alkaline earth metal cations by macrocyclic and diazamacrobicyclic polyethers, composed of ordered arrays of hard oxygen (and nitrogen) donor atoms, underpinned the development of host–guest supramolecular chemistry in the 1970s and 1980s. The arrangement of −OCCO– and −OCCN– chelating units in these preorganized receptors, including, but not limited to, crown ethers and cryptands, is responsible for the very high binding constants observed for their complexes with Group IA and IIA cations. The cyclodextrins (CDs), cyclic oligosaccharides derived microbiologically from starch, also display this −OCCO– bidentate motif on both their primary and secondary faces. The self-assembly, in aqueous alcohol, of infinite networks of extended structures, which have been termed CD-MOFs, wherein γ-cyclodextrin (γ-CD) is linked by coordination to Group IA and IIA metal cations to form metal–organic frameworks (MOFs), is reported. CD-MOF-1 and CD-MOF-2, prepared on the gram-scale from KOH and RbOH, respectively, form body-centered cubic arrangements of (γ-CD)<SUB>6</SUB> cubes linked by eight-coordinate alkali metal cations. These cubic CD-MOFs are (i) stable to the removal of solvents, (ii) permanently porous, with surface areas of ∼1200 m<SUP>2</SUP> g<SUP>–1</SUP>, and (iii) capable of storing gases and small molecules within their pores. The fact that the −OCCO– moieties of γ-CD are not prearranged in a manner conducive to encapsulating single metal cations has led to our isolating other infinite frameworks, with different topologies, from salts of Na<SUP>+</SUP>, Cs<SUP>+</SUP>, and Sr<SUP>2+</SUP>. This lack of preorganization is expressed emphatically in the case of Cs<SUP>+</SUP>, where two polymorphs assemble under identical conditions. CD-MOF-3 has the cubic topology observed for CD-MOFs 1 and 2, while CD-MOF-4 displays a channel structure wherein γ-CD tori are perfectly stacked in one dimension in a manner reminiscent of the structures of some γ-CD solvates, but with added crystal stability imparted by metal–ion coordination. These new MOFs demonstrate that the CDs can indeed function as ligands for alkali and alkaline earth metal cations in a manner similar to that found with crown ethers. These inexpensive, green, nanoporous materials exhibit absorption properties which make them realistic candidates for commercial development, not least of all because edible derivatives, fit for human consumption, can be prepared entirely from food-grade ingredients.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-1/ja208224f/production/images/medium/ja-2011-08224f_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja208224f'>ACS Electronic Supporting Info</A></P>
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