Multicomponent synthesis of pyrrolo[2,1-a]isoindolylidene-malononitrile (PIYM) fluorophores and their photophysical properties

Abstract

From the array of small molecule organic fluorophores available as functional materials and in biology, synthetic procedures that allow for a simpler and rapid synthesis of organic fluorophores with desirable photophysical properties are in high demand. In addition, fluorophores with good brightness and tuneability in both solid and solution states are only available in certain numbers. Herein, we introduce a new family of pyrrolo[2,1-a]isoindolylidene-malononitrile (PIYM) fluorophores that exhibit pronounced emission in the visible region in solution and red-NIR emission in the solid state, with tuneability, efficient brightness and stability. PIYM fluorophores were efficiently synthesized via two simple MCR reaction pathways from commercially available, as well as newly synthesized, building blocks. Furthermore, the observed photophysical nature is rationalized from both electrochemical and theoretical calculations (DFT and TD-DFT). In the future, we anticipate that these PIYM fluorophores, with their excellent stability and lower molecular weight, will open ways to enhance the development of NIR-emitting fluorophores with more significant applications in both materials and biological fields.