Molecular puzzle ring: pseudo[1]rotaxane from a flexible cyclodextrin derivative.
A pseudo[1]rotaxane formed by a flexible cyclodextrin (CD) derivative (1-R) with a bulky end group has been investigated on kinetic quantitation. 1-Rs have the cinnamamide moiety as a guest and a bulky end group (R) as a rate-determining moiety of the threading process. The R groups play an important role for the formation of pseudo[1]rotaxane, and kinetics of the self-inclusion process was found to be controlled by the size and shapes of the R groups. 1-Ad and 1-Me derivatives, which have an adamantyl and methyl end group, respectively, formed self-inclusion complexes by threading of the arm moiety with a conformational conversion of altrose from (1)C(4) form to (4)C(1) form. Flexibility of the altro-alpha-CD cavity resulted in an induced fit (from (1)C(4) to (4)C(1)) to the arm moiety, and introducing a bulky end group allowed the stability of this pseudo[1]rotaxane to be enhanced.
Miyawaki
Atsuhisa
A
Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
Kuad
Paul
P
Takashima
Yoshinori
Y
Yamaguchi
Hiroyasu
H
Harada
Akira
A
D003505:Cyclodextrins / Q000737:chemistry*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D043862:Rotaxanes / Q000138:chemical synthesis* / Q000737:chemistry
D003505:Cyclodextrins; D043862:Rotaxanes