Fluorophores based on the 4-bora-3a,4a-diaza-s-indacene (boron dipyrrin or BODIPY) platform have found diverse applications in different fields of modern science, medicine and (bio)technology. In this review we describe the numerous postfunctionalization methodologies of the boron dipyrrin core designed and realized by research groups around the globe. In the

In this review we describe the various new methodologies for synthetic postmodification of the BODIPY core designed and developed by our research groups, as well as their electronic spectroscopic properties. We discuss the different strategies created for functionalization of the BODIPY framework at the pyrrole C‐ring positions and the meso‐position. Halogenated boron dipyrrins are substrates for nucleophilic substitution or Pd‐catalyzed cross‐coupling reactions. α‐Unsubstituted BODIPYs can be functionalized with N and C nucleophiles through oxidative or vicarious nucleophilic substitution (VNS) of the α‐hydrogen atoms. Combining this methodology with reversible Michael addition onto nitrostyrenes provides a route to 3‐styrylated BODIPYs. Furthermore, the one‐step, Pd‐catalyzed C–H arylation of 3,5‐unsubstituted BODIPYs leads to 3‐ and 3,5‐arylated dyes. Finally, radical C–H arylation at the 3,5‐positions of α‐unsubstituted BODIPYs provides an additional synthesis route to arylated dyes.

The UV-vis electronic absorption and fluorescence emission properties of 8-halogenated (Cl, Br, I) difluoroboron dipyrrin (or 8-haloBODIPY) dyes and their 8-(C, N, O, S) substituted analogues are reported. The nature of the meso-substituent has a significant influence on the spectral band positions, the fluorescence quantum yields, and lifetimes. As a function of the solvent, the spectral maxima of all the investigated dyes are located within a limited wavelength range. The spectra of 8-haloBODIPYs display the narrow absorption and fluorescence emission bands and the generally quite small Stokes shifts characteristic of classic difluoroboron dipyrrins. Conversely, fluorophores with 8-phenylamino (7), 8-benzylamino (8), 8-methoxy (9), and 8-phenoxy (10) groups emit in the blue range of the visible spectrum and generally have larger Stokes shifts than common BODIPYs, whereas 8-(2-phenylethynyl)BODIPY (6) has red-shifted spectra compared to ordinary BODIPY dyes. Fluorescence lifetimes for 6, 8, and 10 have been measured for a large set of solvents and the solvent effect on their absorption and emission maxima has been analyzed using the generalized Catalán solvent scales. Restricted rotation about the C8-N bond in 7 and 8 has been observed via temperature dependent (1)H NMR spectroscopy, whereas for 10 the rotation about the C8-O bond is not hindered. The crystal structure of 8 demonstrates that the short C8-N bond has a significant double character and that this N atom exhibits a trigonal planar geometry. The crystal structure of 10 shows a short C8-O bond and an intramolecular C-H···π interaction. Quantum-chemical calculations have been performed to assess the effect of the meso-substituent on the spectroscopic properties.

We describe herein the first radical CH arylation of BODIPY dyes. This novel, general, one‐step synthetic procedure uses ferrocene to generate aryl radical species from aryldiazonium salts and allows the straightforward synthesis of brightly fluorescent (Φ>0.85) 3,5‐diarylated and 3‐monoarylated boron dipyrrins in up to 86 % yield for a broad range of aryl substituents. In this way, new and complex dyes with red‐shifted spectra can be easily prepared.

A new one-step synthetic method towards 3-and 3,5-arylated BODIPY dyes via palladium-catalysed C-H arylation has been developed and its scope has been investigated.