Visible-Light-Photomeltable Azobenzenes as Solar Thermal Fuels

Abstract

Photomelting of azobenzene is a phenomenon that is typically achieved by UV-light irradiation. However, many applications based on azobenzene photomelting, including the solar thermal fuel (STF) application, require responsiveness to visible light. Therefore, in this study, we designed and synthesized several azobenzene derivatives that melt under visible-light irradiation and explored their potential application as STFs. By combining molecular design elements that endow azobenzene with visible-light-responsiveness (ortho-halogen) and photomeltability (para-alkoxy), we successfully synthesized four compounds that exhibit visible-light photomelting properties. These compounds also exhibit a long cis-isomer lifetime, which makes them good candidates for STFs in the future.