Simple Molecular Machines: Chemically Driven Unthreading and Rethreading of a [2]Pseudorotaxane


  • This research is supported by the Engineering and Physical Sciences Research Council (EPSRC) in the UK, and CNR (Progetto Strategico Tecnologie Chimiche Innovative) and Ministero dell'Università e della Ricerca Scientifica e Tecnologica in Italy. We acknowledge the Ramsay Memorial Trust for providing S. J. L. with a Ramsay Memorial Postdoctoral Fellowship and CibaGeigy (Divisione Additivi) for a grant to A. C. We thank Mr. P. R. Ashton, Dr. N. Spencer, and Mr. M. S. Tolley for recording the mass spectra and 1H NMR spectra of the different adducts.


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The 2,7-dibenzyldiazoniapyrene dication 22+ is unthreaded from the pseudorotaxane 12+ by addition of the aliphatic amine A. Protonation of the amine disrupts the interactions between A and 22+ and thus rethreading of 22+ by 1,5-dinaphtho-[38]crown-10 (3) can occur, making the whole process reversible. The changes in the relative positions of the components can be monitored by absorption and luminescence spectroscopy.