Theoretical Study of Binding Site Preference in [2]Rotaxanes

Area of Science:

• Supramolecular Chemistry
• Computational Chemistry

Background:

• Switchable rotaxanes are molecular machines that change conformation in response to external stimuli.
• Understanding intercomponent binding is crucial for designing functional molecular devices.

Purpose of the Study:

• Investigate binding site preferences in rotaxanes and pseudorotaxanes.
• Elucidate the origins of intercomponent binding, particularly the role of dispersion interactions.

Main Methods:

• Electronic structure calculations at multiple levels of theory.
• Empirical approximations to estimate electrostatic and dispersion contributions.
• Analytic partitioning of binding interactions.

Main Results:

• Dispersion interactions play a significant role in intercomponent binding, especially with π-π stacking.
• Computational methods neglecting dispersion can predict qualitative binding preferences but not quantitative accuracy.
• The study provides insight into the origins of binding interactions in rotaxanes.

Conclusions:

• Accurate quantitative prediction of rotaxane binding requires inclusion of dispersion interactions.
• Qualitative binding preferences can sometimes be captured without dispersion, but this is insufficient for precise molecular design.
• This research clarifies the importance of dispersion in supramolecular chemistry.