Synthetic oligorotaxanes exert high forces when folding under mechanical load

Area of Science:

• Supramolecular Chemistry
• Chemical Engineering
• Materials Science

Background:

• Nature utilizes folding for molecular machines; chemists create synthetic foldamers mimicking this control.
• Mechanically interlocked molecules (MIMs) like rotaxanes and catenanes enable controlled movement.
• Donor-acceptor oligorotaxane foldamers combine MIMs and foldamers, with interlocked parts dictating folded structures.

Discussion:

• Atomic force microscopy-based single-molecule force spectroscopy was used to mechanically unfold synthetic oligorotaxanes.
• Oligorotaxanes composed of 1,5-dioxynaphthalene units and cyclobis(paraquat-p-phenylene) rings were studied.
• Real-time fluctuations between folded and unfolded states were captured.

Key Insights:

• Synthetic oligorotaxanes exert forces up to 50 pN against mechanical loads up to 150 pN.
• Folding transition times are less than 10 microseconds, comparable to proteins.
• The mechanically interlocked structure confers remarkable robustness, exceeding natural protein folding.

Outlook:

• Synthetic oligorotaxanes demonstrate potential to surpass natural folding proteins in performance.
• These findings pave the way for designing novel molecular machines with enhanced capabilities.
• Further research into mechanochemical properties could lead to advanced applications in nanotechnology and materials science.