Features of F₂-BODIPY Synthesis (A Review)

BODIPY derivatives (4,4-difluoro-4-boron-3a,4a-diaza-S-indacene), due to their high molar extinction coefficients, fluorescence quantum yields, and photochemical stability, have gained popularity as optical sensors for bioimaging and detection of various analytes. BODIPY molecules have different substituents not only at the meso-carbon atom, but also at the boron atom. The review describes various synthetic approaches to BODIPY derivatives and «classical» BODIPY, in which the boron atom bears 2 fluorine substituents (F₂-BODIPY). The advantages and limitations of the methods of synthesis are considered, as well as the use of reagents and their popularity are analyzed. Based on the literature, the mechanisms for the synthesis of BODIPY derivatives are proposed, with focus on the reasons affecting the yield of BODIPY derivatives, including a low stability of reagents, by-products formation, and the influence of water.