Rationalizing Guest-Driven Cooperative Effect in a Hierarchical Host-Guest Aqueous Assembly

Area of Science:

• Supramolecular Chemistry
• Materials Science

Background:

• Molecular recognition is crucial for biological functions like hemoglobin and microtubule interactions.
• Understanding cooperative effects in artificial hierarchical assembly in water is often overlooked.

Purpose of the Study:

• To investigate cooperative effects in artificial systems using proximity-induced π-interactions.
• To explore hierarchical self-assembly of supramolecular structures in aqueous media.

Main Methods:

• Spectroscopic techniques
• Microscopic imaging
• Computational analysis
• Isothermal titration calorimetry

Main Results:

• Proximity-induced π-interactions between anthracene-based guests (An≡Py) and cucurbit[8]uril (CB[8]) enhance binding in water.
• Hierarchical self-assembly into 2D flake-like structures via higher-order (2:2) complexation.
• A less favored 2:2 binding mode is formed through concealed guest-interactive species, rationalized by multi-technique analyses.
• A multistate pathway and enthalpy-driven binding process were observed.
• Guest-guest interactions significantly influence binding stoichiometry.

Conclusions:

• Subtle tuning of π-scaffolds drives cooperative hierarchical assembly in water.
• Proximity-induced π-interactions are key to understanding complex supramolecular assembly.
• This study reveals an elusive molecular interaction governing hierarchical organization.