168211-64-1Relevant articles and documents
Catalysis in the Self-Assembly of [2]Rotaxanes and [2]Pseudorotaxanes. Effect of the Length of Polyethereal Side Arms and Terminal Stoppers
D'Acerno, Claudio,Doddi, Giancarlo,Ercolani, Gianfranco,Franconeri, Silvia,Mencarelli, Paolo,Piermattei, Alessio
, p. 1393 - 1396 (2004)
The template effects exerted by compounds 3, 5, 6, and 8 in the ring closure reaction of the trication 13+ to yield the [2] pseudorotaxanes 154+ and 174+ and the [2]rotaxanes 18 4+ and 204+ have been quantitatively evaluated in acetonitrile at 62 °C by UV/vis spectrophotometry. The rate of ring closure of the trication 13+ largely increases in the presence of the templates up to a maximum of ca. 200 times in the case of 5 at a concentration of ca. 0.08 M. The results indicate that, in the self-assembly of a rotaxane, the template effect of the guest is lowered by the presence of two large stoppers (triisopropylsilyl) at the end of the linear chains; this effect is more important the shorter the chain and can be mainly ascribed to steric effects. Previously hypothesized entropic effects appear to be of lesser importance.