Parent, Unsubstituted Corrphycene: Synthesis and Properties

Area of Science:

• Organic Chemistry
• Photochemistry
• Spectroscopy

Background:

• Porphyrin isomers are crucial in various chemical and biological processes.
• Unsubstituted corrphycene (Cp) has been challenging to synthesize and characterize.
• Understanding Cp's electronic and structural properties is key to its applications.

Purpose of the Study:

• To report the synthesis and characterization of unsubstituted corrphycene (Cp).
• To investigate the structural, spectral, and electrochemical properties of Cp.
• To explore the potential of Cp as a sensing material.

Main Methods:

• Synthesis of unsubstituted corrphycene (Cp) and its precursor.
• Structural analysis using X-ray crystallography and spectroscopy (UV-Vis, MCD).
• Electrochemical characterization (cyclic voltammetry).
• Density Functional Theory (DFT) calculations for comparison.

Main Results:

• Successful synthesis of unsubstituted corrphycene (Cp).
• Cp exhibits characteristics of a soft chromophore, similar to porphine.
• Magnetic circular dichroism (MCD) spectra reveal larger HOMO than LUMO orbital splitting, contradicting DFT predictions.
• Corrphycene exists as a doubly degenerate trans tautomeric species with inequivalent intramolecular H-bonds, suggesting a stepwise conversion mechanism.

Conclusions:

• Unsubstituted corrphycene (Cp) is a stable, synthesizable porphyrin isomer.
• Cp's electronic structure and soft chromophore nature make it suitable for sensing applications.
• The observed tautomeric behavior provides insights into molecular dynamics and hydrogen bonding.