Electronic Structure and Hypercorrole Features of Deprotonated Free-Base and Reduced Copper Corroles

Area of Science:

• Coordination Chemistry
• Materials Science
• Computational Chemistry

Background:

• Corroles are macrocyclic ligands with diverse applications.
• Tuning electronic properties of corroles is key for new functionalities.
• Copper corroles are of interest for their catalytic and photophysical properties.

Purpose of the Study:

• Synthesize and characterize novel copper corroles and their ligands.
• Investigate the electronic structure and photophysical properties of these corroles.
• Explore the hypercorrole behavior and near-infrared (NIR) absorption of anionic corroles.

Main Methods:

• Synthesis of copper corroles and their corresponding ligands.
• X-ray crystallography for crystal structure determination.
• Spectroscopic techniques (UV-Vis, fluorescence) and computational methods (CASSCF/NEVPT2) for electronic structure analysis.

Main Results:

• Two copper corroles, 1Cu and 2Cu, and their ligands were synthesized and characterized.
• Anionic corroles with 4-nitrophenyl substituents displayed hypercorrole behavior with intense, red-shifted Q-bands.
• Electronic structure calculations confirmed charge-transfer bands from the corrole core to nitrophenyl substituents, extending into the NIR region.
• 2Cu showed indirect reduction in the presence of F- or OH-, leading to red-shifted Q-bands in polar environments.

Conclusions:

• Easy-to-prepare anionic corroles, metalated and unmetalated, exhibit hypercorrole behavior.
• The observed NIR absorption is attributed to charge-transfer transitions.
• These findings suggest potential applications for these corroles in hyperthermal processes.