Tetracyanobutadiene functionalized ferrocenyl BODIPY dyes

Area of Science:

• Organic Chemistry
• Materials Science
• Photochemistry

Background:

• Boron-dipyrromethene (BODIPY) dyes are known for their unique photophysical properties.
• Ferrocene incorporation into organic molecules can modulate electronic and redox characteristics.
• Tetracyanobutadiene (TCBD) is a strong electron-accepting moiety that can significantly influence molecular properties.

Purpose of the Study:

• To design and synthesize novel ferrocenyl BODIPY derivatives functionalized with tetracyanobutadiene (TCBD).
• To investigate the effect of TCBD incorporation on the photonic and electrochemical properties of ferrocenyl BODIPYs.
• To explore how varying the linkage between the ferrocenyl BODIPY and TCBD units affects molecular behavior.

Main Methods:

• Synthesis of meso alkynylated ferrocenyl BODIPYs.
• Utilizing a [2 + 2] cycloaddition-retroelectrocyclization reaction with tetracyanoethylene (TCNE) to introduce the TCBD unit.
• Characterization of the synthesized TCBD derivatives (2a-2c) using spectroscopic and electrochemical techniques.
• Single crystal X-ray diffraction analysis for structural elucidation.

Main Results:

• Successful synthesis of three TCBD-substituted ferrocenyl BODIPY derivatives (2a-2c) with varying linkage lengths.
• Observed red-shifted absorption spectra in TCBD derivatives (2a-2c) compared to their parent compounds (1a-1c).
• Structural analysis revealed extensive intermolecular hydrogen bonding in TCBD functionalized ferrocenyl BODIPYs (2a, 2c), but a lack of π-π stacking interactions.

Conclusions:

• The incorporation of the electron-withdrawing TCBD unit significantly perturbs the electronic and photonic properties of ferrocenyl BODIPYs.
• The linkage strategy between the ferrocenyl BODIPY and TCBD units influences the observed properties.
• The synthesized compounds present interesting structural features, with hydrogen bonding playing a role in their solid-state packing.