Solvent-Processed Circularly Polarized Luminescence in Light-Harvesting Coassemblies

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Photophysics

Background:

• Solvent polarity's role in regulating chiroptical properties of supramolecular assemblies is underexplored.
• Controlling handedness, dissymmetry factor, and luminescent color in chiral self-assemblies remains a challenge.

Purpose of the Study:

• To investigate solvent control over self-assembly pathways of dynamers.
• To achieve efficient circularly polarized light harvesting and migration in soft matter assemblies.
• To rationally regulate chiroptical properties like dissymmetry factor, color, and handedness.

Main Methods:

• Controlled self-assembly of a dynamer in various solvents to form gels, liposomes, helices, and particles.
• Loading a fluorescent dye as an acceptor for energy transfer studies.
• Circular dichroism spectroscopy to analyze ground-state chirality.
• Spectroscopic analysis of photoexcited states to observe energy transfer and circularly polarized luminescence (CPL).

Main Results:

• Dynamer self-assembly into four distinct soft matter forms (gel, liposome, helix, particles) was achieved through solvent control.
• Efficient energy transfer from donor to acceptor was observed at the photoexcited state, dependent on solvent polarity.
• Apolar decane solvent yielded thixotropic gels with left-handed CPL.
• Luminescent colors were tunable from green to red (510-600 nm) by adjusting acceptor molar fraction, achieving a high dissymmetry factor (10^-2 order of magnitude).
• Ordered structures were crucial for the emergence of CPL.

Conclusions:

• Solvent polarity is a key kinetic factor in regulating chiroptical properties of supramolecular chiral assemblies.
• This work demonstrates a solvent-processed method for controlling CPL properties (dissymmetry factor, color, handedness) via light harvesting and migration.
• The approach avoids complex synthesis of chiral building blocks and enantiomer libraries.