S2 emission from chemically modified BODIPYs.

Area of Science:

• Organic Chemistry
• Photophysics
• Spectroscopy

Background:

• Boron dipyrromethene (BODIPY) dyes are widely used in various applications due to their photophysical properties.
• Extending the absorption and emission of BODIPY dyes to longer wavelengths is crucial for advanced applications.
• Understanding the excited-state dynamics of BODIPY is essential for designing new functional dyes.

Purpose of the Study:

• To synthesize novel BODIPY derivatives with enhanced absorption and emission in the longer wavelength region.
• To investigate the anomalous S(2) emission from the second excited state observed in these new BODIPY compounds.
• To elucidate the photophysical processes governing the S(2) state dynamics.

Main Methods:

• Synthesis of novel boron dipyrromethene (BODIPY) derivatives.
• Spectroscopic measurements including fluorescence up-conversion and transient absorption.
• Theoretical calculations using time-dependent density functional theory (TD-DFT).

Main Results:

• Successful synthesis of BODIPY derivatives with significant absorption and emission in the longer wavelength region.
• Observation of anomalous S(2) emission at shorter wavelengths from the second excited state.
• Determination that the S(2) emission decay time is influenced by internal conversion and intersystem crossing.

Conclusions:

• The synthesized BODIPY derivatives offer promising photophysical properties for longer wavelength applications.
• The photodynamics of the S(2) state in these BODIPY compounds are complex, involving competing relaxation pathways.
• Theoretical calculations support the assignments of electronic transitions and provide insights into the observed photobehavior.