Circular Dichroism and Multiphoton Circularly Polarized Luminescence Switching Using a Bis-perylene Diimide...

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• Chiroptical switches change circular dichroism (CD) or circularly polarized luminescence (CPL) upon stimuli, valuable for sensing and imaging.
• Current chiroptical materials often use UV/visible light, causing cytotoxicity and poor tissue penetration; multiphoton excitation offers an alternative but MP-CPL is difficult to achieve with organic emitters.
• Core-twisted perylene diimides (PDIs) are promising for MP-CPL due to their chiral π-systems and two-photon absorption capabilities.

Purpose of the Study:

• To develop a novel chiroptical material combining switchable CD and MP-CPL.
• To create a stable, yet conformationally dynamic, chiral bis-PDI macrocycle.
• To overcome limitations of UV/visible light excitation in chiroptical applications.

Main Methods:

• Synthesis of a chiral bis-PDI macrocycle incorporating stimuli-responsive elements.
• Characterization of the macrocycle's chiroptical properties, including CD and MP-CPL.
• Investigation of the conformational dynamics and enantiomeric stability of the macrocycle.

Main Results:

• A novel chiral bis-PDI macrocycle with stable, conformationally dynamic enantiomers was successfully synthesized.
• The material demonstrated switchable CD and achieved MP-CPL for the first time in an organic emitter system.
• The integration of chiral PDIs into macrocycles provided configurational stability and tuneable chiral conformations.

Conclusions:

• This work presents a new class of chiroptical materials with potential for advanced sensing and imaging applications.
• The developed bis-PDI macrocycle overcomes the limitations of traditional chiroptical materials by enabling NIR-based MP-CPL.
• This breakthrough paves the way for developing sophisticated chiroptical switches and probes operating via multiphoton excitation.