Excited state proton transfer in 2'-hydroxychalcone derivatives

Area of Science:

• Photophysics and photochemistry
• Organic electronics
• Materials science

Background:

• Excited-state intramolecular proton transfer (ESIPT) fluorophores are vital for advanced applications.
• 2'-hydroxychalcone derivatives exhibit solid-state emission in the deep red/NIR region, unlike their solution behavior.
• Understanding relaxation pathways is key to optimizing these materials.

Purpose of the Study:

• To theoretically investigate gas-phase excited state relaxation pathways in five 2'-hydroxychalcone systems.
• To identify and characterize non-radiative decay channels.
• To elucidate the role of substituents in influencing these relaxation mechanisms.

Main Methods:

• Static and non-adiabatic quantum chemical simulations.
• Analysis of excited state potential energy surfaces.
• Computational modeling of molecular dynamics.

Main Results:

• Two competing non-radiative relaxation channels were identified, driven by intramolecular rotation in excited states.
• Both enol and keto excited state relaxation pathways are accessible across the studied compounds.
• Electron-donating substituents enhance the ESIPT pathway over enol state rotation.

Conclusions:

• The study identifies fundamental relaxation mechanisms governing the emission of 2'-hydroxychalcone derivatives.
• Understanding these pathways is essential for controlling and enhancing solid-state emission.
• This work provides a basis for designing new ESIPT materials with tailored optoelectronic properties.