A conical intersection model to explain aggregation induced emission in diphenyl dibenzofulvene

Area of Science:

• Photochemistry
• Materials Science
• Organic Chemistry

Background:

• Aggregation-induced emission (AIE) is a phenomenon where molecules become emissive upon aggregation.
• Diphenyl dibenzofulvene (DPDBF) is a molecule known to exhibit interesting photophysical properties.
• Intramolecular rotation is often implicated in the non-emissive behavior of organic molecules in solution.

Purpose of the Study:

• To elucidate the mechanism behind the aggregation-induced emission (AIE) of diphenyl dibenzofulvene (DPDBF).
• To investigate the role of intramolecular rotation and conical intersection seams in the photophysical behavior of DPDBF.

Main Methods:

• Computational modeling to study molecular dynamics and electronic structure.
• Spectroscopic analysis in solution and solid states.

Main Results:

• A conical intersection seam was identified as the key factor limiting the intramolecular rotation mechanism for AIE in DPDBF.
• In solution, rotation around the exocyclic fulvene bond allows access to the conical intersection seam, leading to radiationless decay.
• In the solid state, restricted torsion prevents access to the seam, rendering DPDBF emissive.

Conclusions:

• The study reveals that blocking access to the conical intersection seam is crucial for achieving aggregation-induced emission in DPDBF.
• Understanding this mechanism provides insights into designing AIE-active materials by controlling molecular conformation.