Electropolymerizable Ir^III Complexes with β-Ketoiminate Ancillary Ligands

Area of Science:

• Organometallic Chemistry
• Materials Science
• Electrochemistry

Background:

• Cyclometalated iridium(III) complexes are promising for optoelectronic applications.
• Tuning ligand structures is crucial for controlling photophysical and electrochemical properties.
• Electropolymerizable fragments enable film formation for device integration.

Purpose of the Study:

• Synthesize novel electropolymerizable cyclometalated iridium(III) complexes.
• Investigate the impact of β-ketoiminate ligand substitution (CH3 vs. CF3) on electrochemical and photophysical behavior.
• Evaluate the potential for creating stable, emissive films for electronic applications.

Main Methods:

• Synthesis of iridium(III) complexes featuring triphenylamine-based cyclometalated ligands.
• Incorporation of β-ketoiminate ligands with varying methyl (CH3) or trifluoromethyl (CF3) substituents.
• Electrochemical characterization (cyclic voltammetry) and photophysical studies (emission spectroscopy).
• Electrodeposition of thin films onto indium tin oxide (ITO) coated glass substrates.

Main Results:

• Complexes with CH3-substituted β-ketoiminates exhibited luminescence in solution and solid states.
• Stable, emissive films were successfully electrodeposited onto ITO substrates.
• Electrochemical studies indicated emission quenching via electron trapping within the polymer network.
• CF3 substitution led to luminescence quenching and inhibited electropolymerization.

Conclusions:

• Ligand substitution significantly influences the photophysical properties and electropolymerization capability of iridium(III) complexes.
• CH3-substituted complexes are suitable for developing emissive films.
• CF3-substituted complexes are not suitable for electropolymerization or emissive applications due to luminescence quenching.