Mechanochemistry as a Sustainable Method for the Preparation of Fluorescent Ugi BODIPY Adducts

Mechanochemistry, that is, the use of mechanical energy produced by milling or grinding to perform chemical transformations, was used as a green strategy using a minimal amount of solvent for the preparation of highly valuable formyl functionalized BODIPY dyes. The electronic properties of the meso-aryl group play a key role in the fluorescence response of the adducts resulting from the Ugi reaction. Such an understanding of the molecular structure-fluorescence interplay explains the brightness of these dyes in the cellular media monitored by fluorescence imaging. In the present report, we provide flow cytometry and fluorescence microscopy evidence that the novel dyes efficiently stain peripheral blood mononuclear cells (PBMCs) and Candida albicans cells without disturbing cell integrity. Moreover, it is demonstrated that by staining C. albicans cells, we can monitor the early and late steps of phagocytosis, using human monocyte-derived macrophages. The dye series presented herein represent a novel application for formyl functionalized BODIPYs, expanding their applications in monitoring biological processes.