✍ Scribed by Peter R. Ashton; Aaron M. Heiss; Dario Pasini; Françisco M. Raymo; Andrew N. Shipway; J. Fraser Stoddart; Neil Spencer
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Two chiral π-electron-rich crown ethers incorporating either modest diastereoselection (56:44-67:33) occurs during the kinetically controlled self-assembly of the catenanes. The a binaphthol or two D-mannitol units have been synthesized and their abilities to bind bipyridinium guests demonstrated. free energy barriers (12.8-16.8 kcal mol -1 ) associated with the circumrotation of one macrocyclic component through Both crown ethers could be interlocked mechanically with cyclobis(paraquat-p-phenylene) to afford two chiral the cavity of the other and vice versa were determined by variable-temperature 1 H-NMR spectroscopy. In addition, [2]catenanes. Furthermore, these crown ethers were also mechanically interlocked with a tetracationic cyclophane another dynamic process involving the "rocking" of the mean planes of the mechanically interlocked macrocycles incorporating a 2,2Ј-dihydroxy-1,1Ј-binaphthyl spacer to afford mixtures of diastereoisomeric [2]catenanes. The with respect to each other was also identified and the associated free energy barriers (10.3-10.4 kcal mol -1 ) composition of these mixtures was determined by 1 H-NMRspectroscopic and HPLC analyses which revealed that determined.
complexes. Here, we report the syntheses of (i) two chiral π-[a
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