Synthesis and Characterization of a Two-Station Two-Gate Calix[6]arene-Based [2]Catenane.

Area of Science:

• Supramolecular Chemistry
• Nanoscience and Nanotechnology
• Organic Synthesis

Background:

• Bottom-up design of molecular machines is a key area in nanoscience.
• Interlocked molecular architectures like pseudorotaxanes, rotaxanes, and catenanes are crucial for building functional nanoscale devices.
• Calix[6]arene-based Mechanically Interlocked Molecules (MIMs) offer versatile platforms for molecular engineering.

Purpose of the Study:

• To synthesize and characterize a novel two-station, two-gate calix[6]arene-based [2]catenane.
• To integrate azobenzene and stilbene units as functional gates within a molecular track.
• To explore advanced synthetic strategies for constructing complex MIMs.

Main Methods:

• Utilized threading and capping strategies to synthesize precursor [2]rotaxane isomers.
• Employed a supramolecular-assisted approach to overcome challenges in pseudorotaxane synthesis.
• Performed catenation reaction using a trans-stilbene-based bisacyl chloride clipping unit.
• Characterized the final [2]catenane using mass spectrometry and Nuclear Magnetic Resonance (NMR) spectroscopy.

Main Results:

• Successfully synthesized the two-station, two-gate calix[6]arene-based [2]catenane, denoted as C3(azo-down).
• Achieved a 25% yield of the target [2]catenane after purification.
• Confirmed the successful synthesis and specific orientation of the azobenzene gate within the catenane structure.

Conclusions:

• The study presents a new calix[6]arene-based [2]catenane with integrated azobenzene and stilbene gates.
• The developed synthetic methodology, including supramolecular assistance, enables the construction of complex MIMs.
• This work contributes to the advancement of molecular machines and functional nanoscale architectures.