Title: Structural and anion binding aspects of the tiny octaazacryptand
Abstract: The pH sensitivity of the binding of anions with a small octaazacryptand, 1,4,7,10,13,16,21,24-octaazabicyclo[8.8.8]hexacosane (L), has been examined. NMR studies were performed comparing the binding of a variety of anions: fluoride, chloride, bromide, iodide and nitrate, with the hexatosylate salt of L at pD 2.0 and 4.0. Results indicate that significant complexation only occurs between L and fluoride at pD 4.0 and with chloride and fluoride at pD 2.5 and lower. No binding was observed at either pD with the other anions examined. Crystallographic findings obtained for the chloride (1), [H6L(Cl)][Cl]5·2.75H2O, iodide (2), [H4L(H2O)][I]4·4H2O, and mixed chloride/nitrate (3), [H6L(Cl)][NO3]5·1.5H2O·CH3OH, complexes of L were obtained. For 1 and 3, L is hexaprotonated and a chloride ion is inside the cavity. In the iodide salt, 2, a molecule of water is encapsulated and L is tetraprotonated.
Publication Year: 2002
Publication Date: 2002-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 19
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