Solvent-induced reversible solid-state colour change of an intramolecular charge-transfer complex

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Organic Electronics

Background:

• Intramolecular charge-transfer (CT) complexes are crucial in developing responsive materials.
• Understanding solid-state color changes is key for material design.

Purpose of the Study:

• To design and characterize a dynamic intramolecular CT complex with solvent-responsive solid-state color.
• To elucidate the mechanism behind the observed dichromatism.

Main Methods:

• Synthesis of a novel pyrene-naphthalenediimide based CT complex.
• Solid-state spectroscopic analysis (UV-Vis, fluorescence).
• Solvent-vapor exposure experiments and structural analysis.

Main Results:

• The designed CT complex showed reversible color changes in the solid-state upon treatment with various organic solvents.
• Dichromatism was directly linked to the inclusion of solvent molecules within the crystal lattice.
• Solvent inclusion induced significant alterations in the relative orientation of the pyrene (donor) and naphthalenediimide (acceptor) units.

Conclusions:

• A dynamic intramolecular CT complex capable of reversible solid-state color changes was successfully developed.
• The findings demonstrate a new strategy for creating solvent-responsive materials based on controlled molecular orientation.
• This work has implications for sensor development and smart materials with tunable optical properties.