BODIPY Dyes and Their Analogues

This chapter discusses organoboron complexes, especially the synthesis and correlation between molecular structure and optical properties. Organoboron complexes are among the most important fluorescent dyes. Boron complexation of the ligand (dye) contributes to the enhancement of the fluorescent properties of the dye through rigidization of the chromophore, which restricts non-radiative processes. Additionally, the optical properties of organoboron complexes, such as absorption and fluorescence maxima, and fluorescence quantum yields are strongly dependent on the ligand type (dye). Therefore, boron complexation of the ligand (dye) is an efficient strategy to synthesize novel fluorescent dyes. In fact, organoboron complexes have been actively developed and applied in various fields, including optoelectronics and biomedicine. Understanding synthetic methods and the correlation between molecular structure and optical properties help us in producing materials with the desired properties. This chapter discusses BODIPY dyes, the most famous fluorescent organoboron complexes, and then outlines the four-coordinate monoboron complexes possessing anionic bidentate ligands (N^N, N^O, O^O, and other types) and multinuclear boron complexes, with a special focus on the results reported by the author.