Dual Emission with Efficient Phosphorescence Promoted by Intermolecular Halogen Interactions in Luminescent...

Area of Science:

• Materials Science
• Inorganic Chemistry
• Photochemistry

Background:

• Developing Zn-based phosphorescent materials is challenging due to limited ligand-centered (LC) transitions.
• Metal complexes often exhibit fluorescence, but achieving efficient phosphorescence requires specific strategies.

Purpose of the Study:

• To synthesize and characterize novel tetranuclear Zn(II) clusters with dual emission properties.
• To investigate the role of halogen substitutions and intermolecular halogen bonding in inducing phosphorescence.

Main Methods:

• Synthesis of tetranuclear Zn(II) clusters with varying halogen substitutions (iodine, bromine, chlorine).
• Single-crystal X-ray structural analysis to determine molecular structure and intermolecular interactions.
• Variable-temperature emission spectroscopy to study photophysical properties, including fluorescence and phosphorescence.

Main Results:

• Successfully synthesized [Zn4L4(μ3-OMe)2X2] clusters incorporating iodine-substituted ligands.
• Observed dual emissions (fluorescence and strong green phosphorescence) with emission maxima at 510-522 nm.
• Confirmed that intermolecular halogen interactions induce heavy-atom effects, leading to efficient phosphorescence with long lifetimes (0.78-0.95 ms at 77 K).

Conclusions:

• Introduction of halogen interactions, particularly iodine, is an effective strategy for inducing phosphorescence in fluorescent Zn(II) complexes.
• The synthesized tetranuclear Zn(II) clusters demonstrate promising photoluminescent properties.
• This study offers a new pathway for designing phosphorescent materials based on metal complexes.