A Dynamic Metal-Organic Radical Emission System

Abstract

Developing new organic radical emission systems and regulating their luminescence properties presents a significant challenge. Herein, we build dynamic and multi-emission band radical luminescence systems by co-assembling inorganic metal salts with carbonyl compounds in ionic liquids. After the assembling, dual-band, and excitation wavelength-dependent emission was observed upon ultraviolet light irradiation, one emission band originates from carbonyl radical after light irradiation, the other band from the ligand-metal charge transfer (LMCT) state, which benefits from the charge transfer from the radicals to the metal salts. The dual emission centers also introduce excitation wavelength-dependent properties for the molecules. In addition, three-band emission covering the visible and near-infrared regions can be shown when two or three kinds of metal ions are simultaneously doped into the radical system driven by the ligand-metal-metal charge transfer (LMMCT). Interestingly, visible light can quickly quench the radical emission of systems, thus realizing a dynamic luminescence. The LMMCT effect and strong supramolecular interactions significantly improve the photoluminescence quantum yield by up to 67.2 %. Moreover, such materials can be successfully used for detecting radioactive metal ions and information encryption. This study develops a platform for manufacturing various metal-organic radical emission systems with diverse properties.