Stacking Transformation-Triggered Circularly Polarized Luminescence Reversion in γ-Cyclodextrins-Pyrene Co-Assembly

Area of Science:

• Supramolecular Chemistry
• Chiral Materials Science
• Photophysics

Background:

• Cyclodextrins (CDs) are widely explored for creating chiral circularly polarized luminescence (CPL)-active materials due to their inherent chirality and host-guest capabilities.
• A significant challenge remains in achieving reversed CPL emission control using single-handed chiral cyclodextrin moieties.

Purpose of the Study:

• To design and synthesize novel γ-cyclodextrin (γ-CD)-based host-guest complexes.
• To investigate the mechanism behind reversed CPL emission regulation in these single-handed chiral systems.
• To explore the role of excimer stacking in controlling CPL emission.

Main Methods:

• Synthesis of γ-CD-based host-guest complexes incorporating dual pyrene imidazolium derivatives with multiple linkers.
• Characterization of the photophysical properties, including circularly polarized luminescence (CPL) emission.
• Analysis of excimer formation and stacking conformations within the γ-CD/pyrene complexes.

Main Results:

• The synthesized γ-CD/pyrene host-guest complexes successfully exhibited reversed circularly polarized emission.
• The transformation and nature of excimer stacking within the γ-CD cavity were identified as the key factor for the inverted CPL.
• Both (+)- and (-)-circularly polarized excimer emission (CPEE) were observed, correlating with right- and left-handed stacking conformations, respectively.

Conclusions:

• This study demonstrates a novel strategy for achieving reversed CPL emission using single-handed γ-cyclodextrins.
• The findings highlight the critical role of controlled excimer stacking in modulating CPL signals from chiral supramolecular assemblies.
• The developed system offers a promising platform for designing advanced chiral light-emitting materials.