Synthesis, Structural Characterization and Reactivity of Macrocyclic Cyclo[2]malonates

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Macrocyclic compounds are crucial in molecular recognition and materials science.
• Synthesizing specific macrocyclic structures, particularly dimeric forms, often presents challenges due to competing oligomerization.

Purpose of the Study:

• To develop a controlled synthesis for a new class of oxygen-bridged cyclo[2]-malonates.
• To investigate the structural, conformational, and supramolecular properties of these novel macrocycles.
• To explore the potential of these macrocycles in molecular recognition, specifically vanadyl ion binding.

Main Methods:

• Condensation reaction between malonyl dichloride and substituted benzylic α,ω-diols.
• Optimization of reaction conditions to favor dimeric macrocycle formation.
• Single-crystal X-ray diffraction for structural and conformational analysis.
• Investigation of supramolecular assembly through intermolecular interactions (hydrogen bonding, halogen bonding).

Main Results:

• Successful controlled synthesis of oxygen-bridged cyclo[2]-malonates, selectively yielding dimeric macrocycles.
• X-ray diffraction confirmed well-defined conformations, tunable cavity sizes, and substituent-dependent stereochemistry.
• Macrocycles self-assemble into interlocked columnar structures stabilized by hydrogen and halogen bonding.
• Vanadyl (VO2+) binding is influenced by macrocycle cavity size and preorganization, indicating a structure-function relationship.

Conclusions:

• Oxygen-bridged cyclo[2]-malonates represent an accessible and versatile macrocyclic platform.
• These macrocycles offer tunable structural features and predictable supramolecular behavior.
• The findings suggest significant potential for applications in molecular recognition and the design of functional materials.