Toward a single-layer two-dimensional honeycomb supramolecular organic framework in water

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Chemistry

Background:

• Achieving well-defined 2D supramolecular polymers in solution remains a significant challenge.
• Existing methods often struggle with solubility and controlling self-assembly into ordered structures.

Purpose of the Study:

• To design and synthesize a novel triangular molecule capable of forming 2D supramolecular frameworks in aqueous solution.
• To investigate the self-assembly process and characterize the resulting 2D supramolecular organic framework (SROF).

Main Methods:

• Synthesis of a rigid, stacking-forbidden 1,3,5-triphenylbenzene derivative with peripheral bipyridinium units and hydrophilic groups.
• Solution-phase self-assembly induced by mixing the triangular molecule with cucurbit[8]uril (CB[8]) in a specific molar ratio.
• Characterization using (1)H NMR spectroscopy, dynamic light scattering, X-ray diffraction/scattering, and microscopy (scanning probe and electron).

Main Results:

• Successful formation of the first single-layer, 2D supramolecular organic framework in solution.
• The framework exhibits a periodic honeycomb structure stabilized by host-guest complexation between cucurbit[8]uril and bipyridinium units.
• Hydrophilic groups effectively suppressed 1D stacking and ensured aqueous solubility of the triangular precursor.

Conclusions:

• The designed triangular molecule and cucurbit[8]uril enable the controlled self-assembly of 2D supramolecular polymers in water.
• This work presents a significant advancement in creating solution-phase 2D supramolecular architectures.
• The developed system offers a new platform for designing functional 2D materials through self-assembly.