Photomodulated Morphologies in Halogen Bond-Driven Assembly during Gel-Sol Transition

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Photochemistry

Background:

• Photoresponsive supramolecular gels are sought after for their dynamic properties.
• Controlling gel morphology changes with light remains a significant challenge in materials science.

Purpose of the Study:

• To develop a supramolecular gel with well-defined, light-induced morphological changes.
• To explore the relationship between photoisomerization, supramolecular interactions, and gel structure.

Main Methods:

• Synthesis of an azopyridine-containing molecule (Azopy-C10) and its self-assembly with 1,4-tetrafluorodiiodobenzene via halogen bonding.
• Investigation of gel-sol transitions and morphological transformations upon UV irradiation.
• Analysis of microstructural changes correlated with cis-isomer content and halogen-bonding strength.

Main Results:

• A supramolecular gel was successfully formed through halogen bonding.
• UV irradiation induced a gel-sol transition via azopyridine trans-cis isomerization.
• Morphologies transitioned from flake to fluffy bobble-like and peony-like structures with increasing UV exposure time.

Conclusions:

• The study presents a novel photoresponsive supramolecular gel with tunable morphologies.
• The material demonstrates a unique method for photomodulating structures, expanding applications in areas like information storage and anticounterfeiting.