Alkane guest packing drives switching between multimeric deep-cavity cavitand assembly states.

Area of Science:

• Supramolecular Chemistry
• Molecular Modeling
• Physical Chemistry

Background:

• Deep-cavity cavitands like TEMOA form dynamic multimeric assemblies in aqueous solutions.
• The aggregation states of these cavitands are influenced by various factors, including guest molecules.
• Understanding these aggregation phenomena is crucial for designing functional supramolecular systems.

Purpose of the Study:

• To investigate the role of alkane guests in the formation of TEMOA assemblies.
• To correlate molecular simulation results with experimental observations of aggregation transitions.
• To elucidate the driving forces behind the stabilization of multimeric cavitand complexes.

Main Methods:

• Molecular dynamics (MD) simulations were employed to study alkane guest transfer into TEMOA assemblies.
• Free energy calculations were performed to quantify the energetics of guest incorporation.
• Comparison of simulation data with experimental aggregation state transitions.

Main Results:

• Calculated alkane transfer free energy minima strongly correlate with experimentally observed aggregation states (dimeric, tetrameric, hexameric).
• Guest packing within the cavitand assemblies is identified as a key factor stabilizing multimeric complexes.
• The simulations provide a rationale for the absence of experimentally observed octameric TEMOA assemblies.

Conclusions:

• Molecular simulations effectively predict and explain the aggregation behavior of TEMOA cavitands in the presence of alkane guests.
• Guest-host interactions, specifically packing, play a critical role in the self-assembly of these supramolecular structures.
• The study offers insights into the limitations of experimental observation for higher-order aggregates.