Helicene-Fluorescein Hybrids: A Reversible Base-Triggered (Chir)optical Switch with Sign Inversion of Circularly...

Area of Science:

• Organic Chemistry
• Materials Science
• Biophysical Chemistry

Background:

• Chirality and luminescence are key properties for advanced materials.
• Developing stimuli-responsive fluorescent probes is crucial for biological imaging.

Purpose of the Study:

• To design and synthesize novel circularly-polarized luminescence (CPL) materials.
• To investigate the acid/base-responsive and chiroptical switching behavior of helicene-fluorescein hybrids.
• To explore their potential as chiral fluorescent probes in live-cell imaging.

Main Methods:

• Synthesis of helicene-fluorescein hybrids.
• Spectroscopic analysis (fluorescence and CPL spectroscopy).
• Time-dependent density functional theory (TD-DFT) calculations.
• Live-cell imaging experiments using HeLa cells.

Main Results:

• Synthesized hybrids exhibit reversible switching from blue to red fluorescence with pH change.
• Demonstrated rare base-triggered CPL sign inversion and enhanced dissymmetry factors.
• TD-DFT calculations elucidated the structural basis for switching.
• Intracellular red emission observed in HeLa cells with minimal cytotoxicity.

Conclusions:

• Helicene-fluorescein hybrids are effective pH-responsive CPL materials.
• The compounds show significant potential as chiral fluorescent probes for biological applications.
• The study provides insights into the design of advanced chiroptical materials.