Stepwise Modulation of Bridged Single-Benzene-Based Fluorophores for Materials Science

In recent years, researchers studying fluorogenic samples have steadily shifted from using large, expensive, poorly soluble fluorophores with complex synthetic sequences to smaller, simpler π scaffolds with low molecular weight. This research article presents an in-depth study of the photophysical properties of five bridged single-benzene-based fluorophores (SBBFs) investigated for their solution and solid-state emission (SSSE) properties. The compounds O₄, N₁O₃, N₂O₂, N₃O₁, and N₄ are derived from a central terephthalonitrile core and vary in the amount of oxygen and nitrogen bridging atoms. These minimalized emitters show full-color tunable emission properties and exhibit moderate-to-high photoluminescence quantum yield values reaching up to 0.78 in dimethyl sulfoxide (DMSO). In addition to demonstrating excellent compatibility in poly(methyl methacrylate) (PMMA) films and additive manufacturing using stereolithography (SLA), white light emission was achieved in both solution and 3D-printed materials by controlling the mixing ratio of the compounds. Employing density-functional theory (DFT), well-correlating theoretical absorption and emission wavelengths were calculated as average values of the different possible conformers. Furthermore, cellular internalization of the substances was accomplished using Pluronic^® F-127 nanoparticles. Overall, this study emphasizes the remarkable properties of single-benzene-based emitters, showcasing their accessibility and potential applications in biomedical fields and materials science.