Photomodulation of Charge Transfer through Excited-State Processes: Directing Donor-Acceptor Binding Dynamics.

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Photochemistry

Background:

• Modulating charge transfer (CT) interactions is crucial for developing advanced materials.
• Donor-acceptor (D-A) systems are key components in supramolecular chemistry and materials science.
• Controlling CT interactions dynamically in the solid state remains a significant challenge.

Purpose of the Study:

• To demonstrate the first reversible photomodulation of D-A CT interactions in the solid state.
• To explore the potential of pyridinium-based chromophores for light-controlled molecular interactions.
• To investigate the relationship between molecular structure, CT dynamics, and observable properties.

Main Methods:

• Synthesis of pyridinium-based chromophores with π-conjugated D-A structures.
• Utilizing rotatable C-C single bonds for molecular structure tunability.
• Employing alternate light irradiation to induce photoinduced electron transfer (ET) and excited-state conformational changes.
• Characterizing the reversible modulation of intermolecular CT interactions and associated property changes.

Main Results:

• Demonstrated reversible switching of D-A CT interactions in the solid state using light.
• Observed dual emission properties of the pyridinium-based chromophore dependent on excitation wavelengths.
• Showcased light-induced modulation of molecular affinity between donor and acceptor molecules.
• Confirmed visual color switching and fluorescence on-off as feedback signals for CT modulation.

Conclusions:

• The developed pyridinium-based chromophores enable unprecedented reversible photomodulation of solid-state D-A CT interactions.
• Synergistic effects of photoinduced ET and conformational changes are key to this light-responsive behavior.
• This work opens new avenues for designing smart materials with dynamic and tunable physicochemical properties.