A synthetic molecular pentafoil knot

Area of Science:

• Supramolecular Chemistry
• Chemical Synthesis
• Molecular Topology

Background:

• Molecular knots are increasingly found in biological and synthetic macromolecules.
• Chemical synthesis has focused on creating complex knots for two decades.
• Understanding and synthesizing molecular knots is crucial for advanced materials science.

Purpose of the Study:

• To report the synthesis of the most complex non-DNA molecular knot to date.
• To demonstrate a novel self-assembly strategy for creating intricate molecular architectures.
• To explore the application of design elements in supramolecular chemistry.

Main Methods:

• One-pot self-assembly of bis-aldehyde and bis-amine building blocks around metal cations.
• Characterization using NMR spectroscopy, mass spectrometry, and X-ray crystallography.
• Analysis of the resulting pentafoil knot structure and topology.

Main Results:

• Successful synthesis of a 160-atom-loop molecular pentafoil knot with five crossing points.
• Confirmation of a symmetrical closed-loop double helicate structure.
• Identification of a chloride anion templating the knot via ten CH···Cl(-) hydrogen bonds.

Conclusions:

• The reported self-assembly reaction represents a significant advancement in synthesizing complex molecular knots.
• The strategies employed can be applied to the rational design of other higher-order interlocked molecular architectures.
• This work expands the possibilities in supramolecular chemistry and the creation of novel molecular structures.