Improving two-photon active cross-section value of perylene diimide derivatives through intramolecular photocyclization

Abstract

The approach of using two-photon absorption can reduce material damage and ensure better penetrability due to lowering both the absorption and scattering. Simultaneously increasing the two-photon absorption cross-section and the fluorescence quantum yield of perylene diimide derivatives is a challenging but important task. In a previous study, a regioisomerism strategy by changing the substituent from the bay-position to ortho-position was proved to be an efficient way to enhance the two-photon absorption cross-section. However, the fluorescence quantum yield was decreased instead. In this research study, we present a facile and effective method to simultaneously increase the two-photon absorption cross-section and the fluorescence quantum yield. This method is based on the annulation of the bay region of perylene diimide derivatives to convert the nonfused bay-substituted product to the fused bay-substituted product. The results prove that this fusion strategy is very effective for electron-donating substituents.