Reproducible chiroptical activity from aggregated chiral thienopyrroledione-fluorene π‑conjugated polymers

Area of Science:

• Materials Science
• Polymer Chemistry
• Optoelectronics

Background:

• Chiral π‑conjugated polymers are of interest for their chiroptical properties.
• Chiral aggregated structures in polymers can lead to significant chiroptical responses.

Purpose of the Study:

• To design, synthesize, and characterize novel fluorene-thienopyrroledione polymers with single chiral centers.
• To investigate the chiroptical properties of these polymers in aggregated states.
• To optimize sample preparation for reproducible chiroptical responses.

Main Methods:

• Direct arylation polycondensation for polymer synthesis.
• Chiroptical characterization including circular dichroism (CD) and circularly polarized luminescence (CPL).
• Systematic study of solvent-mixing parameters (e.g., dropwise addition of 1-butanol in CHCl3) to induce aggregation.

Main Results:

• Polymers (R)- and (S)-PFTPD were synthesized with minimal defects.
• Stable aggregates exhibiting strong CD and CPL were formed upon addition of 1-butanol.
• Optimized dropwise addition yielded highly reproducible CD spectra with high dissymmetry factors (|g_abs| = 1.5 × 10⁻², |g_lum| = 1.9 × 10⁻²).

Conclusions:

• Precise control over the solvent-mixing process is crucial for reproducible chiroptical properties in polymer aggregates.
• The chiral thienopyrroledione unit is a promising building block for developing high-performance chiroptical polymer materials.
• The synthesized polymers demonstrate potential for applications requiring strong chiroptical responses.