Docker A, Marques I, Kuhn H, Zhang Z, Félix V, Beer PD. Selective Potassium Chloride Recognition, Sensing, Extraction, and Transport Using a Chalcogen-Bonding Heteroditopic Receptor.
J Am Chem Soc 2022;
144:14778-14789. [PMID:
35930460 PMCID:
PMC9394446 DOI:
10.1021/jacs.2c05333]
[Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
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Chalcogen bonding (ChB) is rapidly rising to prominence
in supramolecular
chemistry as a powerful sigma (σ)-hole-based noncovalent interaction,
especially for applications in the field of molecular recognition.
Recent studies have demonstrated ChB donor strength and potency to
be remarkably sensitive to local electronic environments, including
redox-switchable on/off anion binding and sensing capability. Influencing
the unique electronic and geometric environment sensitivity of ChB
interactions through simultaneous cobound metal cation recognition,
herein, we present the first potassium chloride-selective heteroditopic
ion-pair receptor. The direct conjugation of benzo-15-crown-5 ether
(B15C5) appendages to Te centers in a bis-tellurotriazole framework
facilitates alkali metal halide (MX) ion-pair binding through the
formation of a cofacial intramolecular bis-B15C5 M+ (M+ = K+, Rb+, Cs+) sandwich
complex and bidentate ChB···X– formation.
Extensive quantitative 1H NMR ion-pair affinity titration
experiments, solid–liquid and liquid–liquid extraction,
and U-tube transport studies all demonstrate unprecedented KCl selectivity
over all other group 1 metal chlorides. It is demonstrated that the
origin of the receptor’s ion-pair binding cooperativity and
KCl selectivity arises from an electronic polarization of the ChB
donors induced by the cobound alkali metal cation. Importantly, the
magnitude of this switch on Te-centered electrophilicity, and therefore
anion-binding affinity, is shown to correlate with the inherent Lewis
acidity of the alkali metal cation. Extensive computational DFT investigations
corroborated the experimental alkali metal cation–anion ion-pair
binding observations for halides and oxoanions.
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