Photochemical Synthesis of Solvatochromic Fluorophore from the C-C Coupling Reaction for Undergraduate Laboratory Experiment

Photochemical synthesis, in which light is used as an indispensable reagent, is recognized as a green technique for organic synthesis and has been paid extensive attention. In this laboratory experiment for chemistry classes, a photoinduced C-C coupling reaction is introduced, which can be conducted under mild conditions at room temperature. Generally, this reaction requires no photoredox catalyst and only 2 equiv of triethylamine with common LED light (400 nm) as the light source. Here, we report the photochemical synthesis of a favorable fluorophore (4MPB) with high yields (similar to 80%) using 4-iodobenzoate and N-methylpyrrole as the representative reagents in an undergraduate laboratory experiment. Importantly, all participating students were excited about the fluorophores that they synthesized and gained the basic principles of photoluminescence. This experiment is safe, easy to conduct, and cost-effective, and it received positive feedback from the students. The exercise reinforces their skills in photochemical synthesis and introduces students to the significance and importance of light in chemistry, which is a fascinating field in chemical research.