- Structural Analysis and Inclusion Mechanism of Native and Permethylated α-Cyclodextrin-Based Rotaxanes Containing Alkylene Axles
-
Native α-cyclodextrin- (α-CD) and permethylated α-CD (PMeCD)-based rotaxanes with various short alkylene chains as axles can be synthesized through a urea end-capping method. Native α-CD tends to form [3]- or [5]pseudorotaxanes and not [2]- or [4]pseudorotaxanes, which indicates that the coupled CDs act as a single fragment. End-capping reactions of the pseudorotaxanes with C18 and C24 axle lengths do not occur because the axle termini are covered by the densely stacked CDs. The number of PMeCDs on the pseudorotaxane is flexible and mainly depends on the axle length. Peracetylated α-CD (PAcCD)-based rotaxanes are synthesized through O-acetylation of the α-CD-based rotaxanes without any decomposition of the rotaxanated structures. The structures of PMeCD-based [3]- and [4]rotaxanes, and the molecular dynamics calculations on [3]pseudorotaxanes, indicate that the tail face of PMeCDs is regularly directed toward the axle termini. On the basis of the results obtained, it can be concluded that the directions and numbers of CDs in rotaxanes containing short alkylene chains depend on 1)the interactions between CDs, 2)the length of the alkylene axle, and 3)the interactions between the axle end and tail face of the CD. Come on in! Native and permethylated α-cyclodextrin (CD)-based rotaxanes with various short alkylene axles are synthesized with a urea end-capping method. The directions and number of the CD wheels depend on the interactions between CDs, the axle length, and the interactions between axle ends and the tail face of the CDs (see figure).
- Akae, Yosuke,Koyama, Yasuhito,Sogawa, Hiromitsu,Hayashi, Yoshihiro,Kawauchi, Susumu,Kuwata, Shigeki,Takata, Toshikazu
-
p. 5335 - 5341
(2016/04/09)
-
- INTRAMOLECULAR END-TO-END REACTIONS OF PHOTOACTIVE TERMINAL GROUPS LINKED BY POLYMETHYLENE CHAINS.
-
Intramolecular end-to-end reactions of a pair of photoactive terminal groups, dibenz left bracket b,f right bracket azepine (DBA) chromophores, linked by a series of polymethylene chains (DBA-CO(CH//2)//nCO-DBA, n equals 2-30) were studied by two different approaches. One approach is to measure the intramolecular deactivation rate constants of the excited triplet state of terminal DBA groups by the nanosecond laser photolysis and the other is to measure the intramolecular photocyclization rates of these bichromophoric compounds by the quantitative product analysis with GPC. The excited triplet state of the DBA group is the intermediate of the reaction.
- Ashikaga,Ito,Yamamoto,Nishijima
-
p. 198 - 204
(2007/10/02)
-
- Statistical Syntheses of Rotaxanes
-
The acetalisation of the 28-membered cyclic diols 11a, b with the long-chain dibromo ketone 12 gives acetals 13a, b.These compounds react with triphenylmethyllithium to give 17a, b and 18a, b from which the rotaxanes 20a, b are obtained in 0.066 or 0.18 a
- Schill, Gottfried,Beckmann, Wolfgang,Vetter, Walter
-
p. 941 - 954
(2007/10/02)
-
