Host-Guest Complexations of Amine Boranes and Isoelectronic/Isostructural Quaternary Alkylammonium Cations by Cucurbit[7]uril in Aqueous Solution
The host-guest complexation of six amine boranes (R3NBH3) by the macrocyclic host molecule cucurbit[7]uril (CB[7]) in aqueous solution has been investigated using 1H and 11B NMR spectroscopy. The limiting complexation-induced 1H and 11B chemical shift changes indicate that the amine boranes are incl...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Hindawi-Wiley
2019-01-01
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| Series: | Heteroatom Chemistry |
| Online Access: | http://dx.doi.org/10.1155/2019/8124696 |
| Summary: | The host-guest complexation of six amine boranes (R3NBH3) by the macrocyclic host molecule cucurbit[7]uril (CB[7]) in aqueous solution has been investigated using 1H and 11B NMR spectroscopy. The limiting complexation-induced 1H and 11B chemical shift changes indicate that the amine boranes are included in the hydrophobic cavity of the host molecule. The host-guest stability constants for neutral R3NBH3∙CB[7] complexes (in the range of 105-107M-1) have been determined by 1H NMR competition experiments and are compared with the corresponding values for the isoelectronic/isostructural R3NCH3∙CB[7] + complexes. Ammonia borane (H3NBH3) does not form a host-guest complex with CB[7]. The trends in the host-guest stability constant with the guest molar volume are examined, and the stability is ascribed to the hydrophobic effect (packing coefficient) and quadrupole-dipole interactions. |
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| ISSN: | 1042-7163 1098-1071 |