Nanochannel array within a multilayered network of a planarized dehydro[24]annulene

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Crystal Engineering

Background:

• Macrocyclic compounds, such as annulenes, often exhibit complex three-dimensional structures.
• Understanding conformational preferences is crucial for designing materials with specific properties.
• Hydrogen bonding plays a significant role in directing molecular self-assembly.

Purpose of the Study:

• To investigate the crystal structure and conformational behavior of dehydro[24]annulene 1c.
• To compare the solid-state structure of dehydro[24]annulene 1c with related macrocycles 1a and 1b.
• To explore the role of intermolecular interactions in dictating the observed conformations.

Main Methods:

• Single-crystal X-ray diffraction analysis was employed to determine the molecular structures.
• Comparative analysis of the crystal packing and hydrogen bonding networks was performed.
• Conformational analysis was conducted based on the determined crystal structures.

Main Results:

• Dehydro[24]annulene 1c was found to adopt an unusual planar conformation in the crystalline state.
• A multilayered hydrogen-bonded grid structure was observed, creating well-defined nanotubular channels.
• Related macrocycles, 1a and 1b, exhibited the expected non-planar, puckered conformations.

Conclusions:

• The planar conformation of dehydro[24]annulene 1c is a notable deviation from typical macrocyclic behavior.
• The observed crystal packing, driven by hydrogen bonding, facilitates the formation of nanotubular structures.
• This study provides insights into structure-property relationships in macrocyclic systems and their potential for material applications.