Anion/ion pair binding and chiral modulation investigation based on an 18-crown-6-functionalized Schiff base macrocyclic receptor

Abstract

Two π-conjugated fluorescent macrocyclic receptors (MR and C-MR, with C-MR bearing two 18-crown-6 moieties) were successfully synthesized. MR exhibits efficient anion recognition via stable complexes formed by multiple C(sp²)-H•••X⁻ hydrogen bonds. C-MR gains ion pair binding ability from 18-crown-6 groups, enhancing anion affinity through synergistic coordination. Notably, C-MR can effectively modulate the circular dichroism (CD) and circularly polarized luminescence (CPL) responses of chiral phosphate guests. These multifunctional receptors show great potential for selective ion sensors in environmental/biological detection and chiral material engineering.