Luminescent Perhalofluoro Trityl Radicals.

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• Trityl radicals are known for their unique electronic and optical properties.
• Existing polyhalogenated trityl radicals have limitations in fluorescence and stability.
• Developing new luminescent materials with enhanced characteristics is crucial for advanced applications.

Purpose of the Study:

• To synthesize and characterize novel polyfluorinated trityl radicals with high fluorination grades.
• To investigate the electro-optical properties and photostability of these new radicals.
• To explore the potential of these radicals in materials science applications, such as in nanoparticles.

Main Methods:

• Synthesis of perhalofluoro trityl cations via functionalization of perfluorinated trityl cation with trimethylsilyl halides.
• Reduction of perhalofluoro trityl cations using commercial zinc powder to obtain polyfluorinated trityl radicals.
• Characterization of electro-optical properties, including fluorescence quantum yields and luminescence lifetimes.
• Investigation of photostability under light irradiation and stability under ambient conditions.
• Analysis of radical-stained polystyrene nanoparticles for emission properties and excimer formation.
• Structural characterization of oxidation products (peroxides) using single-crystal X-ray diffraction.

Main Results:

• Successful synthesis of three perhalofluoro trityl radicals with high fluorination grades in quantitative yields.
• Polyfluorinated trityl radicals exhibit significantly higher fluorescence quantum yields and longer luminescence lifetimes compared to polychlorinated analogs.
• Expanded emission range extending into the yellow spectral region and enhanced photostability under irradiation.
• Observation of an additional red-NIR emission band in radical-stained polystyrene nanoparticles, attributed to excimer formation.
• Investigation revealed slow conversion with atmospheric oxygen, forming characterized peroxides.

Conclusions:

• The study successfully developed a straightforward method to access highly fluorinated trityl radicals.
• These novel polyfluorinated trityl radicals possess superior electro-optical properties, including enhanced luminescence and photostability.
• The findings open new avenues for designing a wide range of luminescent polyfluorinated trityl radicals for diverse applications.