Multicolor emissive organic material to display aggregation caused red shift with dual state emission, and application towards rewritable data storage

Abstract

The development of dual-state organic luminogens with high emission efficiency both in solution and solid phase is still a difficult task. Dual-state emissive fluorescent materials have proven to have a much broader application in several fields. Molecular design plays a significant role in fabricating switchable as well as tunable emissions. Nonetheless, the mechanism of dual-state emission needs to be studied further. Herein, two compounds, Blue-Yellow emissive material (BYEM) and Green-Red emissive material (GREM), have been designed and synthesized for a novel class of luminogens with dual-state emission (DSEgens) properties. These compounds emit luminously in solution state as well as solid state, with Aggregation Caused Red-Shifted Emission (ACRE) emission. Close-packed molecular structure and the steric hindrance effect can reduce the intramolecular rotation solution state, which accelerates the radiative transition of the compound in the solution state. On the contrary, in the solid state, the twisted structure and intermolecular C–H⋯π interactions can indorse the J-aggregation, which leads to the high fluorescence at the solid state. Significant red shift emission at solid state has been supported by theoretical calculations. On the other hand, by combining a partly shared donor–acceptor unit based on the twisted molecule, these compounds have shown good solvatochromic behavior. Gradual redshift emission has been observed as the solvent polarity is increased. These dual state highly emissive compounds can be applied in several industrial applications as well as the biomedical field.