Small organic fluorophores with SWIR emission detectable beyond 1300 nm

Area of Science:

• Organic Chemistry
• Photophysics
• Materials Science

Background:

• Fluorenone derivatives are known for their optical properties.
• Developing new materials for short-wavelength infrared (SWIR) applications is crucial for advanced imaging.

Purpose of the Study:

• To synthesize and characterize novel fluorenone-based dyes with absorption and emission in the SWIR region.
• To investigate the electronic properties influencing the SWIR optical behavior.

Main Methods:

• Functionalization of 3,6-Dimethylamino fluorenone with specific substituents.
• Theoretical calculations using Time-Dependent Density-Functional Theory (TD-DFT).
• Optical measurements including absorption and emission spectroscopy.
• SWIR imaging using an InGaAs camera and longpass filters.

Main Results:

• Achieved absorption maximum at 1012 nm and emission above 1300 nm for the functionalized fluorenone.
• TD-DFT calculations indicated that substituent orbitals are key to narrowing the HOMO-LUMO energy gap.
• Successful SWIR imaging demonstrated the practical utility of the synthesized dyes.

Conclusions:

• The functionalized 3,6-Dimethylamino fluorenone derivatives are effective SWIR emitters.
• The study provides insights into structure-property relationships for NIR dye design.
• These novel dyes hold promise for applications in SWIR imaging and sensing.