Cation‐binding ability of tactic poly(crown ether)s

Cation‐binding ability of tactic poly(crown ether)s was evaluated by solvent extraction of alkali metal picrates. It was found that isotactic poly(crown ether)s bind particular cations, which can be easily sandwiched by two neighboring crown ether units, a little more effectively than syndiotactic ones. No difference of cation‐binding ability was, however, observed between the corresponding d,l‐ and meso‐bis(crown ether)s. This suggests that the rigidity of the poly(crown ether)s, in combination with the tactic configurations, causes the difference in the cation‐binding ability.