N-Sulfur[n]arene: Synthesis and Solution-State Double-Threaded Dimerization Assisted by Multiple S···S Interactions

Area of Science:

• Supramolecular Chemistry
• Chemical Crystallography
• Solution-State Chemistry

Background:

• Noncovalent interactions, such as σ-hole interactions, are crucial for building discrete supramolecular assemblies.
• These interactions are often weakened or suppressed in solution, limiting their application in dynamic systems.
• Developing methods to harness these interactions in solution is key for designing novel molecular architectures.

Purpose of the Study:

• To demonstrate the solution-phase dimerization of a macrocycle driven by cooperative σ-hole interactions.
• To investigate the structural and dynamic aspects of dimer formation in solution.
• To explore the role of S···S contacts and alkyl-chain threading in stabilizing the dimer.

Main Methods:

• Single-crystal X-ray diffraction to determine the solid-state structure of the dimer.
• Concentration-dependent Nuclear Magnetic Resonance (NMR) spectroscopy to study dimerization in solution.
• Diffusion-Ordered Spectroscopy (DOSY) to assess molecular size and aggregation in solution.

Main Results:

• A double-threaded dimer structure was confirmed in the solid state, stabilized by alkyl-chain penetration and S···S contacts.
• Evidence for dimer formation in solution was observed through concentration-dependent NMR.
• DOSY experiments supported the presence of a stable dimer in solution, indicating cooperative stabilization.

Conclusions:

• Cooperative σ-hole and S···S interactions can effectively drive macrocycle dimerization in solution.
• Alkyl-chain threading and S···S contacts play a crucial role in stabilizing the supramolecular dimer in the solution phase.
• This work highlights a strategy for utilizing weak noncovalent interactions to control self-assembly in solution.