title: A self-assembled homooxacalix[3]arene-based dimeric capsule constructed by a Pd(II)-pyridine interaction which shows a novel chiral twisting motion in response to guest inclusion.
abstract: A capsule-like molecule was constructed by dimerization of pyridine-containing homooxacalix[3]aryl esters utilizing a Pd(II)-pyridine interaction when Li(+) ions were bound to the ionophoric lower rims. (1)H NMR spectral studies showed that the self-assembled molecular capsule 3b.(Li(+))(2) has a highly symmetrical D(3)(h)-structure. It was also found that this self-assembled molecular system can form capsular structures in the presence of Na(+) or ammonium (RNH(3)(+)) ions. Very interestingly, these molecular capsules are twisted into triply bridged helical structures, and chiral RNH(3)(+) guests included in the cavity induce a change in the (P) versus (M) ratio, resulting in high chiral induction ( approximately 70%). These results indicate that the self-assembled molecular capsule 3b has a novel chiral factor in which the (P) versus (M) equilibrium is readily controllable by the inclusion of chiral guest molecules.
authors.affiliation: Contribution from the Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Ikeda
authors.forename: H
authors.initials: H
authors.lastname: Udzu
authors.forename: Z
authors.initials: Z
authors.lastname: Zhong
authors.forename: S
authors.initials: S
authors.lastname: Shinkai
authors.forename: S
authors.initials: S
authors.lastname: Sakamoto
authors.forename: K
authors.initials: K
authors.lastname: Yamaguchi