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Title: Isomorphous but No Dead Ringer: Contrasting the Supramolecular Binding of Tetrafluoroberyllate and Sulfate Ions by Nanojars
An extensive single-crystal X-ray crystallographic study of 11 nanojar structures (of which seven are novel) of the formula [anion⊂{cis-CuII(μ-OH)(μ-pz)}n]2– (anion = BeF42–, n = 28, 31, 32, CunBeF4; anion = SO42–, n = 28, 31, CunSO4; pz = pyrazolate, C3H3N2–) has been carried out, providing a detailed description of isomorphism and pseudopolymorphism in nanojars. The results point to a remarkable variety in the shape of the constituent [cis-CuII(μ-OH)(μ-pz)]x (Cux; x = 6, 8, 9, 10, 12 and 14) metallamacrocycles, despite only small differences in the coordination environment of the individual Cu2+ centers. The flexibility of the Cux rings and, ultimately, of the nanojar framework allows for the incarceration of different anions with slightly different dimensions in a nanojar of a given size, resulting in the formation of isomorphous structures in the case of CunBeF4 and CunSO4. Selectivity studies monitored by electrospray-ionization mass spectrometry (ESI-MS) and proton nuclear magnetic resonance spectroscopy (1H NMR) reveal that despite the virtually identical H-bonding pattern around the two anions in nanojars of a given size, SO42– is strongly preferred over BeF42–. The origins of this selectivity are discussed, along with the nature of bonding in the two isosteric anions. Lastly, the crystal structure of (Bu4N)3Be2F7(H2O)3 documents the formation of the Be2F73– ion from BeF42–.  more » « less
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Author(s) / Creator(s):
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Publisher / Repository:
American Chemical Society
Date Published:
Journal Name:
Crystal Growth & Design
Page Range / eLocation ID:
1676 to 1688
Medium: X
Sponsoring Org:
National Science Foundation
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