<i>N</i>-Arylsulfonamidocalix[4]arenes with narrow pH-responsive binding near neutral pH.

ABSTRACT: We report a series of N-arylsulfonamidocalix[4]arene hosts with tunable acidity and conformational flexibility designed to explore narrow pH-responsive binding. Using two cationic dyes as model guests, we performed a systematic analysis across pH 5.8-10.2 in a 1 : 1 (v/v) water : acetonitrile mixture (χ _H2O 0.74). Fluorescence experiments confirmed pH- and conformation-dependent affinity, with host Tf-SA4 (bearing the most acidic sulfonamide groups in the cone conformer) inducing a sharp fluorescence enhancement within a narrow range of pH _app 7.8 and 8.2 (ΔpH = 0.4). Detailed analysis revealed a 1 : 2 complex with coupled charge and geometry changes in the host that are pH-dependent and induce a steep increase in binding stabili

SUBMITTER: Alarcon-Miranda C 

PROVIDER: S-EPMC12720450 | biostudies-literature | 2026 Feb

REPOSITORIES: biostudies-literature