Prediction of binding constants of alpha-cyclodextrin complexes

Area of Science:

• Supramolecular Chemistry
• Physical Chemistry
• Computational Chemistry

Background:

• Understanding host-guest complexation is crucial in supramolecular chemistry.
• Accurate prediction of binding constants (K11) for cyclodextrin systems remains a challenge.
• Phenomenological theories of pairwise interactions provide a framework for molecular recognition studies.

Purpose of the Study:

• To develop a predictive model for 1:1 alpha-cyclodextrin complex formation constants (K11).
• To incorporate solvent-solute and solute-solute interactions ([Z]) and nonpolar surface area changes (delta A) into binding constant predictions.
• To validate the model across a diverse set of 569 complex systems.

Main Methods:

• Utilized a phenomenological theory of pairwise interactions.
• Developed a quantitative relationship: log K11 = -1.74 - [Z] + 0.032(-delta A).
• Estimated delta A from substrate binding site structure and employed three approximation levels for [Z].

Main Results:

• The model successfully predicted log K11 values for 569 systems.
• At the highest approximation level, predictions agreed within 0.30 units of experimental values in 58% of cases.
• Predictions agreed within 1.00 unit of experimental values in 95% of cases.

Conclusions:

• The developed model provides a robust method for predicting alpha-cyclodextrin binding constants.
• The model effectively integrates solvation, solute-solute interactions, and hydrophobic effects.
• This work advances the quantitative prediction of molecular complexation in aqueous solutions.