Carbazole-based BODIPYs were synthesized in three steps using an organometallic approach consisting of sequential Ir-catalyzed borylation, Suzuki-Miyaura coupling, and boron complexation. Various substituents were introduced into the carbazole moiety, and large substituent effects were confirmed by means of absorption spectroscopy, cyclic voltammetry, and DFT calculations. Dibenzocarbazoles were also converted into the corresponding BODIPYs.

Several carbazole-based boron dipyrromethene (BODIPY) dyes were synthesized by organometallic approaches. Thiazole, benzothiazole, imidazole, benzimidazole, triazole, and indolone substituents were introduced at the 1-position of the carbazole moiety, and boron complexation of each dipyrrin generated the corresponding compounds 1, 2 a, and 3-6. The properties of these products were investigated by UV/Vis and fluorescence spectroscopy, cyclic voltammetry, X-ray crystallography, and DFT calculations. These compounds exhibited large Stokes shifts, and compounds 1, 2 a, and 3-5 fluoresced both in solution and in the solid state. Complex 2 a showed the highest fluorescence quantum yield (ΦF ) in the solid state, therefore boron complexes of the carbazole-benzothiazole hybrids 2 b-f, which had several different substituents, were prepared and the effects of the substituents on the photophysical properties of the compounds were examined. The fluorescence properties showed good correlation with the results of crystal-packing analyses, and the dyes exhibited color-tunable solid-state fluorescence.

Carbazole-based BODIPY dimers 2a-g were synthesized via direct arylation. They showed red-shifted solid-state fluorescence spectra as compared with the corresponding monomer. In addition, unsymmetrical dimers 2d, 2f, and 2g with two different substituents showed red fluorescence with improved quantum yields in the solid state.