Performance of different force fields in force probe simulations

Area of Science:

• Supramolecular Chemistry
• Computational Chemistry
• Materials Science

Background:

• Mechanically interlocked molecules (MIMs) are advanced molecular architectures.
• Calixarenes and catenanes are key components in MIMs, offering unique structural properties.
• Understanding their mechanical behavior is crucial for designing novel functional materials.

Purpose of the Study:

• To investigate the mechanical properties of dimeric calix[4]arene-catenanes using molecular dynamics simulations.
• To compare the performance of three common force fields (GROMOS G53a5, OPLS-AA, AMBER GAFF) in simulating these systems.
• To analyze the role of hydrogen bonding and mechanical interlocking in the system's response to external forces.

Main Methods:

• Force probe molecular dynamics simulations were employed.
• Simulations utilized three distinct force fields: GROMOS G53a5, OPLS-AA, and AMBER GAFF.
• Force ramps were used to determine rupture and rejoin force distributions, alongside hydrogen bond network dynamics analysis.

Main Results:

• The dimeric calix[4]arene-catenane system demonstrated fully reversible mechanical behavior, with self-rejoining after force relaxation.
• All tested force fields qualitatively predicted reversible rebinding.
• Quantitative differences in mean rupture forces were observed, correlating with variations in hydrogen bond network strengths between force fields.

Conclusions:

• The mechanical interlocking in dimeric calix[4]arene-catenanes ensures robust reversible behavior.
• The choice of force field significantly impacts quantitative mechanical parameters, highlighting the need for careful force field selection in simulations.
• Hydrogen bonding plays a critical role in stabilizing different structural states and influencing mechanical response.