Red-to-NIR emissive radical cations derived from simple pyrroles

Area of Science:

• Organic Chemistry
• Biomedical Imaging
• Materials Science

Background:

• Red-to-near-infrared (NIR) fluorophores offer deep tissue penetration and reduced autofluorescence, ideal for bio-imaging.
• Conventional synthesis of these fluorophores is often complex and time-consuming.
• Developing facile methods for preparing red-to-NIR fluorophores from accessible materials is crucial for broader applications.

Purpose of the Study:

• To establish a convenient strategy for synthesizing red-to-near-infrared (NIR) emissive fluorophores.
• To explore the stabilization and application of radical cations generated from electron-rich pyrroles.
• To demonstrate the utility of these novel fluorophores in cellular and in vivo imaging.

Main Methods:

• Air oxidation of electron-rich 2,5-dimethylpyrroles to generate radical cations.
• Stabilization of radical cations via adsorption on silica gel-coated TLC plates or encapsulation in cucurbit[7]uril (CB[7]).
• Characterization using electron paramagnetic resonance (EPR) spectroscopy, theoretical calculations, and one-electron oxidation experiments.

Main Results:

• Successfully generated red-to-NIR emissive radical cations from easily available pyrrole derivatives.
• Demonstrated effective stabilization of these radical cations using silica gel or CB[7].
• Pyrrole-derived radical cations encapsulated in CB[7] showed high specificity for mitochondrial imaging in living cells and long-term stability for in vivo imaging.

Conclusions:

• A convenient and direct strategy for preparing red-to-NIR fluorophores via air oxidation of pyrroles has been developed.
• Stabilized pyrrole-derived radical cations exhibit promising fluorescence properties for bio-imaging.
• These novel fluorophores are suitable for specific cellular and in vivo imaging, offering potential for biomedical applications.