Noncovalent Encapsulation of Cobaltocenium inside Resorcinarene Molecular Capsules
- 27 January 2005
- journal article
- Published by American Chemical Society (ACS) in The Journal of Organic Chemistry
- Vol. 70 (5), 1558-1564
- https://doi.org/10.1021/jo047892w
Abstract
The encapsulation of cobaltocenium (Cob+) inside hexameric molecular capsules of two different resorcinarenes was investigated in dichloromethane solution. Both 1H NMR spectroscopic and voltammetric experiments clearly reveal that Cob+ experiences encapsulation. Diffusion coefficient measurements obtained from PGSE NMR experiments indicate that the molecular capsules exist in dichloromethane solution in the absence of any cations. Bound and free Cob+ ions undergo slow exchange on the NMR time scale, but the bound Cob+ ions rotate and/or tumble freely inside the molecular capsules. Under experimental conditions suitable for voltammetry the encapsulation of Cob+ depends on the nature of the supporting electrolyte. Tetraalkylammonium hexafluorophosphate, tetrafluoroborate, and perchlorate supporting electrolytes prevent the encapsulation of Cob+, while tetraalkylammonium chloride and bromide salts allow it. The nature of the tetraalkylammonium cation plays a smaller role in the encapsulation. Finally, the structure of the resorcinarene also factors into the overall stability of the molecular assembly.Keywords
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