Red fluorescent BODIPY molecular rotor for high microviscosity environments

Area of Science:

• Biochemistry
• Chemical Biology
• Materials Science

Background:

• Microviscosity significantly influences diffusion-controlled biological processes.
• BODIPY molecular rotors are effective, non-invasive tools for visualizing microviscosity.
• Existing green fluorescent probes are limited for imaging thick biological samples, necessitating longer wavelengths.

Purpose of the Study:

• To examine novel β-substituted meso-phenyl-BODIPYs with red emission for microviscosity sensing.
• To develop red fluorescent probes suitable for rigid environments and high viscosity ranges.
• To investigate structure-property relationships for enhanced viscosity sensitivity and reduced environmental sensitivity.

Main Methods:

• Synthesis and characterization of novel β-substituted meso-phenyl-BODIPY derivatives.
• Evaluation of spectral properties (absorbance and fluorescence) of the synthesized probes.
• Assessment of probe response to varying microviscosity, polarity, and temperature.

Main Results:

• A new red fluorescent BODIPY probe, BP-Vinyl-NO2, was developed for sensing microviscosity in rigid environments up to 100,000 cP.
• Modification of the β-phenyl substituent (ortho to meta) in BP-PH-m2M-NO2 redshifted spectra while retaining viscosity sensitivity.
• Nitro-substitution on the meso-phenyl group enhanced viscosity sensitivity and reduced sensitivity to polarity and temperature.

Conclusions:

• Nitro-substituted red fluorescent BODIPY probes are effective for microviscosity sensing.
• These probes are suitable for lifetime-based measurements in challenging biological environments.
• The developed probes offer improved performance for imaging applications requiring longer wavelengths.