From Structure to Function: Designing Iridium Catalysts with Spin-Forbidden Excitation for Low-Energy Light-Driven...

Area of Science:

• Photocatalysis
• Organometallic Chemistry
• Materials Science

Background:

• Iridium(III) complexes are vital photocatalysts.
• Controlling their optoelectronic properties is key for applications.
• Spin-forbidden transitions offer unique excitation pathways.

Purpose of the Study:

• To investigate how ligand modifications affect the optoelectronic properties of iridium(III) catalysts.
• To understand the role of electronic and steric factors in tuning catalyst performance.
• To develop highly oxidizing iridium photocatalysts utilizing spin-forbidden excitation.

Main Methods:

• Synthesis and characterization of a series of iridium(III) complexes.
• Spectroscopic analysis to determine optoelectronic properties.
• Density functional theory (DFT) calculations to model electronic structures and triplet energies.

Main Results:

• Ligand tuning significantly impacts the HOMO and LUMO energies of the iridium complexes.
• DFT calculations show excellent agreement (average error < 0.05 eV) with experimental adiabatic triplet energies.
• Observed effects of electronic and steric tuning are largely additive.

Conclusions:

• Ligand design is a powerful strategy for controlling iridium photocatalyst properties.
• The developed iridium photocatalysts are highly oxidizing and operate via spin-forbidden excitation.
• This work provides a framework for designing efficient photocatalysts for various chemical transformations.