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Abstract We report the synthesis and characterization of sulfated pillar[5]arene hosts (P5S2‐P5S10) that differ in the number of sulfate substituents. All fiveP5Snhosts display high solubility in water (73–131 mM) and do not undergo significant self‐association according to1H NMR dilution experiments. The x‐ray crystal structures ofP5S6,P5S6 ⋅ Me6HDA,P5S8 ⋅ Me6HDA, andP5S10 ⋅ Me6HDAreveal one intracavity molecule ofMe6HDAand several external molecules ofMe6HDAwhich form a network of close methonium ⋅ ⋅ ⋅ sulfate interactions. The thermodynamic parameters of complexation betweenP5Snand the panel of guests was measured by direct or competitive isothermal titration calorimetry. We find that the binding free energy toward a guest becomes more negative as the number of sulfate substituents increase. Conversely, the binding free energy of a specific sulfated pillar[5]arene toward a homologous series of guests becomes more negative as the number of NMe groups increases. The ability to tune the host ⋅ guest affinity by changing the number of sulfate substituents will be valuable in supramolecular polymers, separation materials, and latching applications.
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New Synthetic Route to Water‐Soluble Prism[5]arene Hosts and Their Molecular Recognition Properties**
Abstract We report that the direct macrocyclization of naphthalene monomers bearing ethyl ester functional groups delivers prism[5]arene derivatives, which can be deprotected to yield water‐soluble prism[5]arenes (H1andH3).1H NMR spectroscopy showed that dicationic guests bind with the hydrophobic cores buried inside the anisotropic magnetically shielding cavity. Isothermal titration calorimetry measurements showed thatH1andH3are high‐affinity hosts in PBS‐buffered water with Kavalues exceeding 109 M−1for a select guest. The complexation events are driven by the non‐classical hydrophobic effect, CH⋅⋅⋅π interactions, and electrostatic interactions. HostH1displays somewhat higher affinity toward a common guest than pillar[6]arene bearing carboxylic acid functional groups but is significantly less potent than pillar[6]arene bearing sulfate groups.H1andH3should be considered alongside other high affinity hosts for a variety of chemical and biological applications.
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- PAR ID:
- 10372838
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Chemistry – A European Journal
- Volume:
- 28
- Issue:
- 56
- ISSN:
- 0947-6539
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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