Parent, Unsubstituted Hemiporphycene: Synthesis and Properties

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Photochemistry

Background:

• Porphyrins are essential macrocyclic compounds with diverse applications.
• Porphycene is a known isomer of porphyrin, but other constitutional isomers remain largely unexplored.
• Understanding isomer properties is crucial for designing new functional molecules.

Purpose of the Study:

• To synthesize and characterize the parent hemiporphycene (HPc), a nitrogen-in constitutional isomer of porphyrin.
• To investigate the structural, spectral, photophysical, electrochemical, and theoretical properties of HPc.
• To compare HPc properties with those of porphyrin and porphycene.

Main Methods:

• Synthesis of parent hemiporphycene (HPc).
• Comprehensive characterization including structural, spectral, photophysical, and electrochemical analyses.
• Theoretical calculations to support experimental findings.

Main Results:

• HPc was successfully synthesized and characterized.
• HPc displays properties intermediate between porphyrin and porphycene.
• Unique tautomerism was observed in HPc due to its low symmetry and inequivalent nitrogen atoms, with a significantly slower tautomerization rate compared to porphycene.
• Inequivalent intramolecular hydrogen bonds in HPc exhibit unusual characteristics.

Conclusions:

• Hemiporphycene represents a new class of porphyrin isomers with tunable properties.
• The low symmetry and inequivalent nitrogen atoms in HPc lead to distinct tautomeric behavior and hydrogen bonding characteristics.
• HPc serves as a valuable model for studying intramolecular hydrogen bonding in complex molecular systems.