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Diastereoselective Self‐Assembly of [2]Catenanes
Author(s) -
Ashton Peter R.,
Heiss Aaron M.,
Pasini Dario,
Raymo Françisco M.,
Shipway Andrew N.,
Stoddart J. Fraser,
Spencer Neil
Publication year - 1999
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(199905)1999:5<995::aid-ejoc995>3.0.co;2-k
Subject(s) - catenane , chemistry , self assembly , nanotechnology , combinatorial chemistry , organic chemistry , molecule , materials science
Two chiral π‐electron‐rich crown ethers incorporating either a binaphthol or two D ‐mannitol units have been synthesized and their abilities to bind bipyridinium guests demonstrated. Both crown ethers could be interlocked mechanically with cyclobis(paraquat‐ p ‐phenylene) to afford two chiral [2]catenanes. Furthermore, these crown ethers were also mechanically interlocked with a tetracationic cyclophane incorporating a 2,2′‐dihydroxy‐1,1′‐binaphthyl spacer to afford mixtures of diastereoisomeric [2]catenanes. The composition of these mixtures was determined by 1 H‐NMR‐spectroscopic and HPLC analyses which revealed that modest diastereoselection (56:44–67:33) occurs during the kinetically controlled self‐assembly of the catenanes. The free energy barriers (12.8–16.8 kcal mol –1 ) associated with the circumrotation of one macrocyclic component through the cavity of the other and vice versa were determined by variable‐temperature 1 H‐NMR spectroscopy. In addition, another dynamic process involving the “rocking” of the mean planes of the mechanically interlocked macrocycles with respect to each other was also identified and the associated free energy barriers (10.3–10.4 kcal mol –1 ) determined.