Chiral recognition of octadentate Na+ complex with tetra-armed cyclen by molecularly imprinted polymers

Chiral indanyl substituted tetra-armed cyclens (TAC) formed octadentate complexes with Na+. Since their four side arms stand up and are bundled to form quadruplicated helical structures, they can have (delta)- or (lambda)-types enantiomers based on complex helicity. In this study, TAC-imprinted polymers were prepared using an ion-pair complex of the sodium salt of (S)-indanyl substituted TAC (TAC(S)) and 2-sulfoethyl methacrylate as a template, and ethylene glycol dimethacrylate as a cross-linker. Affinity of the obtained polymers for the TAC Na+ complexes was evaluated chromatographically and the imprinted polymer gave longer retention time for the template than that for its antipode where the separation factor was given to be 1.29–1.45 under the NaOH concentrations of 10–25 mM in the eluent. These results indicate that the imprinted polymer could discriminate helix structures of TAC Na+ complexes.