Tuning Anion-Binding Properties of 22-Membered Unclosed Cryptands by Structural Modification of the Lariat Arm.

ABSTRACT: A series of 22-membered unclosed cryptands end-capped with intra-annular methyl (1), phenyl (2), p-tert-butylphenyl (3), and p-nitrophenyl (4) amide substituents (lariat arm) were synthesized to elucidate the effect of steric and electronic factors on their anion recognition behavior. The ¹H NMR titrations in DMSO-d ₆ with 0.5% water reveal enhanced selectivity for H₂PO₄ ^- vs Cl^- and PhCO₂ ^-. The para-attachment of the electron-withdrawing nitro group (-NO₂ vs -H and -t-Bu) was found to increase anion-binding affinity, whereas the steric bulkiness of lariat arm (methyl vs aryl) has a marginal effect. DFT calculations reveal

SUBMITTER: Dabrowa K 

PROVIDER: S-EPMC7676298 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature