Rhodium-Catalyzed Enantioselective Synthesis of Highly Fluorescent and CPL-Active Dispiroindeno[2,1-c]fluorenes

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Chiral helical molecules are of great interest for advanced optical applications.
• Developing efficient synthetic routes to complex chiral architectures remains a challenge.

Purpose of the Study:

• To report the first enantioselective synthesis of chiral [7]-helical dispirodihydro[2,1-c]indenofluorenes (DSF-IFs).
• To investigate the photophysical properties, including circularly polarized luminescence (CPL) and fluorescence quantum yields, of the synthesized DSF-IFs.

Main Methods:

• Enantioselective intramolecular [2+2+2] cycloaddition catalyzed by a Rh/SEGPHOS® complex.
• Synthesis of tethered triynediols and indenofluorenediols.
• Characterization of the resulting DSF-IFs and their CPL and fluorescence properties.

Main Results:

• Successful synthesis of chiral DSF-IFs with high yields and excellent enantiomeric ratios (er up to 99:1).
• The synthesized DSF-IFs exhibit significant circularly polarized luminescence (g_lum =∼10^-3).
• Exceptionally high fluorescence quantum yields (Φ_lum up to 0.97) were observed for the helical compounds.

Conclusions:

• The Rh/SEGPHOS® catalyzed cycloaddition provides an efficient route to enantiopure helical DSF-IFs.
• These DSF-IFs are promising candidates for applications in chiral photonics and optoelectronics due to their strong CPL activity and high fluorescence efficiency.