Conversion of curved assemblies into two dimensional sheets

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Organic Chemistry

Background:

• The creation of organic two-dimensional (O2D) sheets and their transformation into curved nanostructures is a developing field.
• Molecular design requires specific features like multiple interaction sites and inherent twists to achieve curvature.

Purpose of the Study:

• To investigate the self-assembly of a twisted conjugated small molecule, iso-Indigo (i-Indigo), into curved nanostructures and O2D sheets.
• To explore the role of non-covalent interactions (hydrogen bonding, van der Waals, π-π) in directing the assembly process.

Main Methods:

• Synthesis of the iso-Indigo molecule with inherent twists and functional moieties for intermolecular interactions.
• Solution-based self-assembly in a single solvent to form different nanostructures (rings, toroids, O2D sheets).
• Investigation of structural transformations by altering solvent properties, specifically introducing hydrogen bond competitors.

Main Results:

• Iso-Indigo self-assembles into ordered rings and toroids when hydrogen bonding, van der Waals, and π-π interactions are active.
• Addition of solvents that compete for hydrogen bonds causes the disassembly of rings and toroids into O2D sheets.
• Control molecules lacking these specific interactions form only random aggregates, highlighting the importance of i-Indigo's design.

Conclusions:

• The study demonstrates a facile, single-solvent method for fabricating curved nanostructures and O2D sheets from a designed small molecule.
• The findings highlight the crucial role of multiple, tunable non-covalent interactions in controlling supramolecular assembly and nanostructure morphology.
• This work offers a simplified approach to creating complex organic nanostructures, advancing the field of O2D materials.