A pyridine-N-oxide catenane for cation recognition

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Materials Science

Background:

• Catenanes are mechanically interlocked molecular architectures with unique properties.
• Pyridine-N-oxide moieties can act as coordinating sites and hydrogen bond acceptors.
• Developing efficient synthetic routes to complex interlocked molecules remains a challenge.

Purpose of the Study:

• To describe a rapid method for synthesizing a pyridine-N-oxide containing [2]catenane.
• To characterize the synthesized [2]catenane using advanced analytical techniques.
• To investigate the host-guest properties of the [2]catenane, specifically its cation binding and protonation behavior.

Main Methods:

• Rapid synthesis of the pyridine-N-oxide [2]catenane.
• Characterization using Nuclear Magnetic Resonance (NMR) spectroscopy and mass spectrometry.
• X-ray single crystal structure determination for precise structural analysis.
• Proton (¹H) NMR titration experiments to study cation binding and protonation.

Main Results:

• Successful and rapid preparation of the target pyridine-N-oxide [2]catenane.
• Full structural and compositional confirmation via NMR, mass spectrometry, and X-ray crystallography.
• ¹H NMR titration data indicated reversible protonation of the [2]catenane.
• The [2]catenane demonstrated preferential binding of lithium cations over sodium cations.

Conclusions:

• A facile synthetic route to a functionalized [2]catenane has been established.
• The pyridine-N-oxide [2]catenane exhibits interesting supramolecular properties, including pH-responsiveness and selective ion recognition.
• This work provides a foundation for designing advanced molecular machines and sensors based on catenane architectures.