Host-guest complexes with protein-ligand-like affinities: computational analysis and design

Area of Science:

• Supramolecular Chemistry
• Computational Chemistry
• Host-Guest Chemistry

Background:

• Cucurbit[7]uril (CB[7]) macrocycles exhibit strong host-guest complexation in water.
• Guests with nonpolar cores and cationic substituents show exceptionally high binding affinities for CB[7].
• Understanding the driving forces behind these interactions is crucial for designing novel host-guest systems.

Purpose of the Study:

• To investigate the physical principles governing the high-affinity binding of specific guests to cucurbit[7]uril.
• To computationally evaluate a new series of potential cucurbit[7]uril ligands.
• To elucidate the roles of electrostatics and configurational entropy in host-guest complexation.

Main Methods:

• Utilized the Mining Minima algorithm for computational analysis.
• Modeled the binding of ferrocene-based guests with cucurbit[7]uril and beta-cyclodextrin.
• Designed and computationally tested novel bicyclo[2.2.2]octane-based ligands.

Main Results:

• Computational results accurately reproduced experimental observations for ferrocene-guest affinities.
• The study provides a unified perspective on the contributions of electrostatics and configurational entropy.
• Mining Minima predicts ultrahigh binding affinities for the newly designed bicyclo[2.2.2]octane ligands with CB[7].

Conclusions:

• Electrostatics and configurational entropy are key determinants of high-affinity host-guest binding with cucurbit[7]uril.
• The computational approach validates the design strategy for new high-affinity ligands.
• Novel bicyclo[2.2.2]octane compounds are predicted to exhibit strong binding to cucurbit[7]uril, similar to ferrocene derivatives.