Chiral Tetraphenylene-Bridged Carbaporphyrin Dimer

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Chiral Materials Science

Background:

• Carbaporphyrins are macrocyclic compounds with potential applications in catalysis and materials science.
• Chiral macrocycles with helical structures are of interest for enantioselective recognition and catalysis.
• Developing methods for synthesizing and resolving complex chiral molecules is crucial for advancing stereochemistry.

Purpose of the Study:

• To synthesize a novel chiral carbaporphyrin dimer featuring a tetraphenylene bridge.
• To resolve the enantiomers of the carbaporphyrin dimer and its bis-copper complex.
• To investigate the chiroptical properties, specifically the absorption dissymmetry factor (|g_abs|), of the synthesized compounds.

Main Methods:

• Yamamoto-type coupling for synthesizing the carbaporphyrin dimer precursor.
• High-performance liquid chromatography (HPLC) on a chiral stationary phase for enantiomeric resolution.
• Metalation with copper(II) acetate to form bis-copper complexes.

Main Results:

• Successful synthesis of a tetraphenylene-bridged chiral carbaporphyrin dimer (1) with a double π-helical structure.
• Stable resolution of enantiomers (R-1 and S-1) achieved via chiral HPLC, with a maximum |g_abs| of 0.024.
• Enantiopure bis-copper complexes (R-1·Cu and S-1·Cu) were formed, exhibiting enhanced Cotton effects and a maximum |g_abs| of 0.034 due to increased rigidity.

Conclusions:

• The study demonstrates the successful construction of a highly distorted, axially chiral carbaporphyrin dimer with a double π-helical structure.
• Enantioselective synthesis and resolution of the carbaporphyrin dimer and its metal complexes were achieved, yielding significant chiroptical properties.
• The findings offer new strategies for designing chiral carbaporphyrinoids with enhanced optical activity for advanced applications.