Rationally Designed Maleimide Dyes for Large Stokes Shifted Solvatochromism and Aggregation-Induced Emission

Area of Science:

• Organic Chemistry
• Photophysics
• Materials Science

Background:

• Developing small molecule fluorophores with tunable photophysical properties is crucial but challenging.
• Simple synthetic strategies are highly desired for efficient fluorophore design.

Purpose of the Study:

• To present an easy synthetic strategy for N-H maleimide-based fluorescent small molecules.
• To achieve large Stokes shift, solvatochromism, and aggregation-induced emission (AIE) through π-surface extension.

Main Methods:

• Synthesis of N-H maleimide-based fluorescent small molecules (2a-c).
• Photophysical characterization including emission spectra, solvatochromism, and Stokes shift determination.
• Aggregation-induced emission (AIE) studies in THF/water mixtures.
• Density Functional Theory (DFT) calculations for theoretical support.

Main Results:

• Synthesized fluorophores (2a-c) exhibit tunable emission from blue to yellow (458-568 nm).
• Demonstrated large Stokes shifts (110-192 nm) and significant solvatochromism due to intramolecular charge transfer.
• Observed aggregation-induced emission (AIE) properties, influenced by phenyl ring addition and solvent polarity.

Conclusions:

• The developed synthetic strategy effectively tunes photophysical properties of N-H maleimide fluorophores.
• The synthesized molecules show promise for applications requiring tunable emission and AIE characteristics.
• Experimental findings are corroborated by DFT studies, validating the molecular design principles.