Molecular Triangles: A New Class of Macrocycles

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Chemistry

Background:

• Macrocycles are crucial in supramolecular chemistry due to their recognition and self-assembly properties.
• Rigid macrocycles with π-conjugated units offer persistent shapes and large π-surfaces for host-guest interactions and supramolecular architectures.
• Incorporating π-conjugated units imparts optical, electronic, and magnetic properties, leading to applications in materials science and molecular nanotechnology.

Purpose of the Study:

• To design and synthesize a new class of rigid macrocycles: molecular triangles.
• To investigate the structural features, self-assembly characteristics, and physicochemical properties of these molecular triangles.
• To explore the potential applications of molecular triangles in various fields.

Main Methods:

• Synthesis of rigid molecular triangles using chiral trans-1,2-cyclohexano apexes and aromatic tetracarboxylic diimide linkers (e.g., pyromellitic diimide, naphthalene diimide, perylene diimide).
• Systematic investigation of structural features and self-assembly behavior.
• Characterization of molecular recognition, chiral assembly, and electronic properties.

Main Results:

• Developed facile synthetic protocols for creating equilateral and isosceles molecular triangles.
• Demonstrated shape-persistent, electron-deficient cavities capable of complexing anions and electron-rich molecules, forming supramolecular nanotubes and 2D tilings.
• Observed self-assembly into helical superstructures with chirality transfer and unique through-space electron delocalization leading to exotic electronic and spin properties.
• Exhibited diverse physicochemical properties including anion recognition, chiral assembly, gelation, energy storage, luminescence, and nonlinear optical response.

Conclusions:

• Molecular triangles represent a versatile class of rigid macrocycles with tunable geometries and properties.
• Their electron-deficient cavities and chiral nature enable sophisticated molecular recognition and self-assembly.
• These macrocycles hold significant promise for advanced applications in materials science, molecular nanotechnology, and beyond.