Efficient production of [n]rotaxanes by using template-directed clipping reactions.
In this article, we report on the efficient synthesis of well defined, homogeneous [n]rotaxanes (n up to 11) by a template-directed thermodynamic clipping approach. By employing dynamic covalent chemistry in the form of reversible imine bond formation, [n]rotaxanes with dialkylammonium ion (-CH(2)NH(2)(+)CH(2)-) recognition sites, encircled by [24]crown-8 rings, were prepared by a thermodynamically controlled, template-directed clipping procedure, that is, by mixing together a dumbbell compound containing a discrete number of CH(2)NH(2)(+)CH(2)- ion centers with appropriate amounts of a dialdehyde and a diamine to facilitate the [n]rotaxane formation. A 21-component self-assembly process is operative during the formation of the [11]rotaxane. The oligomeric dumbbells containing CH(2)NH(2)(+)CH(2)- ion recognition sites were prepared by a stepwise protocol. Several of the dynamic [n]rotaxanes were converted into their kinetically stable counterparts, first by reduction ("fixing") of imine bonds with the BH(3).THF complex, then by protonation of the complex by addition of acid.
Wu
Jishan
J
Department of Chemistry and Biochemistry, University of California, 405 Hilgard Avenue, Los Angeles, CA 90095, USA.
Leung
Ken Cham-Fai
KC
Stoddart
J Fraser
JF
D005561:Formates / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D043862:Rotaxanes / Q000138:chemical synthesis* / Q000737:chemistry
D005561:Formates; D043862:Rotaxanes; C030544:formic acid