A self-assembled homooxacalix[3]arene-based dimeric capsule constructed by a PdII-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]-atyl esters utilizing a Pd-II-pyridirre interaction when Li+ ions were bound to the ionophoric lower rims. H-1 NMR spectral Studies showed that the self-assembled molecular capsule 3b . (Li+)(2) has a highly symmetrical D-3h-structure. It was also found that this self-assembled molecular system can form capsular structures in the presence of Na+ Or ammonium (RNH3+) ions. Very interestingly, these molecular capsules are twisted Into triply bridged helical structures, and chiral R*NH3+ guests included in the cavity induce a change in the (P) versus (M) ratio, resulting in high chiral induction (similar to 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.