Homoleptic Alkynylphosphonium Au(I) Complexes as Push-Pull Phosphorescent Emitters

Area of Science:

• Organometallic Chemistry
• Materials Science
• Photophysics

Background:

• Development of novel luminescent materials is crucial for advanced optical applications.
• Push-pull emitters and organometallic complexes offer tunable photophysical properties.
• Designing molecules with specific charge transfer characteristics is key to controlling emission.

Purpose of the Study:

• Synthesize novel alkynyl-functionalized phosphonium compounds (P1-P4).
• Prepare homoleptic bis-alkynyl Au(I) complexes (1-4) using these ligands.
• Investigate the photophysical properties, including fluorescence and phosphorescence, of the synthesized compounds and complexes.

Main Methods:

• Chemical synthesis of organic ligands and organogold complexes.
• Photoluminescence spectroscopy to characterize emission properties (fluorescence and phosphorescence).
• Time-dependent density functional theory (TD-DFT) calculations to understand electronic structure and excited states.

Main Results:

• Compounds P1-P4 showed efficient blue and near-UV fluorescence.
• Organogold complexes 1-4 exhibited bright phosphorescence and dual emission.
• Complex 3 displayed warm white emission in solution and pure white emission in films.
• TD-DFT revealed a hybrid MLCT/ILCT nature of the T1 excited state with charge transfer across a ligand-centered "D-π-A" system.

Conclusions:

• The synthesized organogold complexes demonstrate tunable photophysical properties through linker variation.
• The study highlights the successful application of the organometallic "D-π-A" construction concept.
• These materials show potential for applications requiring efficient white light emission.