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Abstract Cooperativity plays a critical role in self‐assembly and molecular recognition. A rigid aromatic oligoamide macrocycle with a cyclodirectional backbone binds with DABCO‐based cationic guests in a 2 : 1 ratio in high affinities (Ktotal≈1013 M−2) in the highly polar DMF. The host–guest binding also exhibits exceptionally strong positive cooperativity quantified by interaction factors α that are among the largest for synthetic host–guest systems. The unusually strong positive cooperativity, revealed by isothermal titration calorimetry (ITC) and fully corroborated by mass spectrometry, NMR and computational studies, is driven by guest‐induced stacking of the macrocycles and stabilization from the alkyl end chains of the guests, interactions that appear upon binding the second macrocycle. With its tight binding driven by extraordinary positive cooperativity, this host–guest system provides a tunable platform for studying molecular interactions and for constructing stable supramolecular assemblies.
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Rational Control of Self‐Recognition of Macroionic γ‐Cyclodextrin by Host‐Guest Interaction with Super‐Chaotropic Borate Cluster Ions
Abstract We report a feasible method to control self‐recognition during the self‐assembly of a hydrophilic macroion, phosphate‐functionalized γ‐cyclodextrin (γ‐CD‐P), though host‐guest interactions. We confirmed that γ‐CD‐P can form a host‐guest complex with a super‐chaotropic anion, namely the B12F122−borate cluster, by using NMR spectroscopy and isothermal titration calorimetry. The loaded γ‐CD‐P, which has a higher charge density, can be distinguished from the uncomplexed γ‐CD‐P, leading to self‐sorting behavior during the self‐assembly process, confirmed by the formation of two types of individual supramolecular structures (Rhof ca. 57 nm and 18 nm, determined by light scattering) instead of hybrid structures in mixed dilute solution. This self‐recognition behavior is accounted for by the difference in intermolecular electrostatic interactions arising from the loading.
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- PAR ID:
- 10238636
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemPlusChem
- Volume:
- 85
- Issue:
- 10
- ISSN:
- 2192-6506
- Format(s):
- Medium: X Size: p. 2316-2319
- Size(s):
- p. 2316-2319
- Sponsoring Org:
- National Science Foundation
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