High binding yet accelerated guest rotation within a cucurbit 7 uril complex. Toward paramagnetic gyroscopes and rolling nanomachines
Abstract
The (15-oxo-3,7,11-triazadispiro[5.1.5.3]hexadec-7-yl)oxidanyl, a bis-spiropiperidinium nitroxide derived from TEMPONE, can be included in cucurbit[7]uril to form a strong (Ka ∼ 2 × 105 M−1) CB[7]@bPTO complex. EPR and MS spectra, DFT calculations, and unparalleled increased resistance (a factor of ∼103) toward ascorbic acid reduction show evidence of deep inclusion of bPTO inside CB[7]. The unusual shape of the CB[7]@bPTO EPR spectrum can be explained by an anisotropic Brownian rotational diffusion, the global tumbling of the complex being slower than rotation of bPTO around its “long molecular axis” inside CB[7]. The CB[7] (stator) with the encapsulated bPTO (rotator) behaves as a supramolecular paramagnetic rotor with increased rotational speed of the rotator that has great potential for advanced nanoscale machines requiring wheels such as cucurbiturils with virtually no friction between the wheel and the axle for optimum wheel rotation (i.e. nanopulleys and nanocars). Show more
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https://doi.org/10.3929/ethz-b-000103106Publication status
publishedExternal links
Journal / series
NanoscaleVolume
Pages / Article No.
Publisher
Royal Society of ChemistryOrganisational unit
03810 - Jeschke, Gunnar / Jeschke, Gunnar
Notes
Received 19 May 2015, Accepted 04 June 2015, First published online 12 June 2015.More
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