Chiral Binaphthalene Building Blocks for Self-Assembled Nanoscale CPL Emitters

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Materials Science

Background:

• Chiral binaphthalene derivatives are valuable scaffolds for creating materials with unique optical properties.
• Controlling the self-assembly of organic molecules into ordered structures is crucial for developing advanced functional materials.

Purpose of the Study:

• To synthesize chiral binaphthalene-based chromophores incorporating biuret hydrogen-bonding sites.
• To investigate the self-assembly behavior of these chromophores into vesicle-like aggregates.
• To characterize the chiroptical properties of the resulting aggregates.

Main Methods:

• Suzuki-Miyaura coupling for chromophore synthesis.
• Scanning electron microscopy (SEM) for aggregate morphology analysis.
• Circularly polarized absorption and emission spectroscopy for chiroptical property evaluation.

Main Results:

• Successful synthesis of luminescent chiral binaphthalene chromophores with tunable emission (blue to yellow-green).
• Spontaneous formation of hollow spherical aggregates (200-800 nm diameter) observed via SEM.
• Strong asymmetry in circularly polarized absorption spectra and observable circular polarization in emission (g_lum ≈ 10⁻³), enhanced upon aggregation.

Conclusions:

• Biuret functionalization of chiral binaphthalene chromophores effectively directs self-assembly into vesicle-like structures.
• These self-assembled aggregates exhibit significant chiroptical activity, demonstrating potential for applications in chiral optics.
• The study highlights a viable strategy for designing responsive and optically active supramolecular materials.