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

摘要: 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 strong (Ka ∼ 2 × 105 M−1) CB[7]@bPTO complex. EPR and MS spectra, DFT calculations, unparalleled increased resistance (a factor of ∼103) toward ascorbic acid reduction show evidence deep inclusion bPTO inside CB[7]. unusual shape the spectrum explained by an anisotropic Brownian rotational diffusion, global tumbling complex being slower than rotation around its “long molecular axis” CB[7] (stator) with encapsulated (rotator) behaves as supramolecular paramagnetic rotor speed rotator that has great potential for advanced nanoscale machines requiring wheels such cucurbiturils virtually no friction between wheel axle optimum (i.e. nanopulleys nanocars).