Anthraphane: An Anthracene-Based, Propeller-Shaped D(3h)-Symmetric Hydrocarbon Cyclophane and Its Layered Single...

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry
• Crystal Engineering

Background:

• Cyclophanes are macrocyclic organic compounds with unique structural properties.
• Anthracene-based cyclophanes are of interest for their photophysical and self-assembly characteristics.
• Controlling intermolecular interactions in cyclophane crystals is crucial for applications like topochemical photopolymerization.

Purpose of the Study:

• To develop an optimized synthesis of the D3h-symmetric cyclophane, anthraphane.
• To investigate the crystallization behavior and solid-state packing motifs of anthraphane.
• To understand the factors influencing π-π interactions between anthracene units in anthraphane crystals.

Main Methods:

• Gram-scale synthesis of anthracene-1,8-ditriflate and subsequent cyclophane formation.
• Single-crystal X-ray diffraction (SC-XRD) to analyze crystal structures and packing.
• Electrostatic potential surface (EPS) calculations using the PM3 method to study electronic properties.

Main Results:

• Anthraphane was synthesized efficiently and readily crystallized into micron-sized single crystals.
• Crystallization consistently resulted in layered structures, but anthracene π-π interactions varied significantly.
• Observed motifs included edge-to-face (etf) and mixed etf/face-to-face (ftf) interactions; exclusive ftf stacking was absent.
• EPS calculations indicated a strong negative surface potential on anthracene faces, likely preventing ftf interactions.

Conclusions:

• The study provides a robust synthesis for anthraphane and detailed insights into its crystallization behavior.
• Understanding the interplay of crystal packing and electronic properties is key to controlling intermolecular interactions.
• These findings offer valuable guidance for designing cyclophanes with desired solid-state arrangements for applications such as photopolymerization.