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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 that binding of H2PO4 - is associated with minimal conformational change in the lariat arm moiety and involve four hydrogen bond acceptor and one donor sites of host.

SUBMITTER: Dabrowa K

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

REPOSITORIES: biostudies-literature

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

Dąbrowa Kajetan K Niedbała Patryk P Pawlak Marcin M Lindner Marcin M Ignacak Wiktor W Jurczak Janusz J

ACS omega 20201104 45

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-</ ...[more]

PMID: 33225192

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