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.
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.
Ikeda
A
A
Contribution from the Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka 812-8581, Japan.
Udzu
H
H
Zhong
Z
Z
Shinkai
S
S
Sakamoto
S
S
Yamaguchi
K
K