Issue 28, 2015

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).

Graphical abstract: High binding yet accelerated guest rotation within a cucurbit[7]uril complex. Toward paramagnetic gyroscopes and rolling nanomachines

Supplementary files

Article information

Article type
Paper
Submitted
19 May 2015
Accepted
04 Jun 2015
First published
12 Jun 2015
This article is Open Access
Creative Commons BY license

Nanoscale, 2015,7, 12143-12150

High binding yet accelerated guest rotation within a cucurbit[7]uril complex. Toward paramagnetic gyroscopes and rolling nanomachines

G. Casano, F. Poulhès, T. K. Tran, M. M. Ayhan, H. Karoui, D. Siri, A. Gaudel-Siri, A. Rockenbauer, G. Jeschke, D. Bardelang, P. Tordo and O. Ouari, Nanoscale, 2015, 7, 12143 DOI: 10.1039/C5NR03288A

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