Achieving Photon Upconversion in Mononuclear Lanthanide Molecular Complexes at Room Temperature.

Area of Science:

• Materials Science
• Inorganic Chemistry
• Photochemistry

Background:

• Photon upconversion luminescence at the molecular scale is a rare phenomenon with significant potential.
• Lanthanide ions, particularly erbium (Er³⁺), are known for their luminescence properties.

Purpose of the Study:

• To investigate photon upconversion luminescence in an eight-coordinate erbium molecular complex.
• To explore strategies for tuning upconversion emissions in mononuclear erbium complexes.

Main Methods:

• Synthesis of an eight-coordinate erbium molecular complex involving Er³⁺, dibenzoylmethane, and 2,2'-bipyridine.
• Direct excitation of the complex at 980 nm to observe upconversion luminescence.
• Introduction of fluoride ions to the complex and analysis of changes in emission spectra and intensity.

Main Results:

• The erbium molecular complex exhibited green upconversion emissions at 525 nm and 545 nm upon 980 nm excitation.
• The addition of fluoride ions induced a new red emission at 667 nm.
• Fluoride ion incorporation enhanced both green and red emission intensities by up to 13-fold.

Conclusions:

• A novel strategy for adjusting green and red emissions in mononuclear erbium complexes was demonstrated.
• The findings broaden the design possibilities for lanthanide-based molecular upconversion systems.
• This research highlights the potential of molecular design for controlling upconversion luminescence.