RESUMEN
In this contribution, we explored the photocyclization of thioethers to highly substituted dibenzothiophenes (DBT) using solely UV-light without any need for additives. This cost-effective, robust and environmentally friendly approach yielded phosphorescent compounds, which were characterized through X-ray crystallography and state-of-the-art photophysical methods. The resulting DBTs feature ultralong photoluminescence lifetimes and quantum yields close to unity in frozen glassy matrices. The reaction mechanism was investigated in detail through a combination of quantum chemical calculations and experimental results, providing evidence that triplet states are involved in the cyclization process. Additionally, the photoreaction can also be induced within materials. For this purpose, the precursors can be integrated into polymer films or polymer resins suitable for 3D printing. Irradiation of these polymeric objects allows motifs with ultralong phosphorescence to be irreversibly inscribed through the proceeding photocyclization. The in situ photogeneration of DBTs from aromatic thioethers overcomes the observed incompatibilities regarding solubility in polymer resins for 3D printing.
RESUMEN
Fluorescence spectroscopy proves to be a powerful and versatile tool in scientific research, demanding ongoing advancements of fluorescence probes to cater to a broad range of applications. The particular interest lies in the development of fluorophores with multiplexing capability, emitting from more than one excited state depending on the polarity and viscosity of the surrounding medium. Here, we present a variety of novel dual planarized intramolecular charge transfer (PLICT) emitters based on cyano-1-aminoindole structures. We have chosen a combination of experimental studies, theoretical calculations and the creation of a unique fluorophore cataloging map. This map serves as a useful tool for empirically determining the origin of both fluorescence bands.
RESUMEN
Three different alkyne-terminated aggregation-induced emission molecules based on a para-substituted di-thioether were attached to the surface of ultrasmall gold nanoparticles (2 nm) by copper-catalyzed azide-alkyne cycloaddition (click chemistry). They showed a strong fluorescence and were well water-dispersible, in contrast to the dissolved AIE molecules. The AIE-loaded nanoparticles were not cytotoxic and easily penetrated the membrane of HeLa cells, paving the way for an intracellular application of AIE molecules, e.g., for imaging.