Chapter 5
BODIPY Dyes and Their Analogues
Yasuhiro Kubota
Abstract 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 (NˆN, NˆO, OˆO, and other types)
and multinuclear boron complexes, with a special focus on the results reported by
the author.
Keywords Boron-complexation · BODIPY · Fluorescence · Pyridomethene ·
Near-infrared dye
5.1 Three-Coordinate Organoboron Compounds
Boron is classified as a metalloid and has a wide range of applications such as
glass (borosilicate glass), ceramics, cleaning products, insecticides, drugs (bortezomib), etc. (Das et al. 2013). A boron atom is essentially three-coordinate possessing
three sp
2 hybrid orbitals and a vacant p-orbital. Trivalent (three-coordinate) boron
compounds generally have a trigonal-planar geometry with 120° bond angles
Y. Kubota (B)
Gifu University, Gifu, Japan
e-mail: kubota@gifu-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2021
Y. Ooyama and S. Yagi (eds.), Progress in the Science of Functional Dyes,
https://doi.org/10.1007/978-981-33-4392-4_5
119
BODIPY Dyes and Their Analogues
Yasuhiro Kubota
Abstract 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 (NˆN, NˆO, OˆO, and other types)
and multinuclear boron complexes, with a special focus on the results reported by
the author.
Keywords Boron-complexation · BODIPY · Fluorescence · Pyridomethene ·
Near-infrared dye
5.1 Three-Coordinate Organoboron Compounds
Boron is classified as a metalloid and has a wide range of applications such as
glass (borosilicate glass), ceramics, cleaning products, insecticides, drugs (bortezomib), etc. (Das et al. 2013). A boron atom is essentially three-coordinate possessing
three sp
2 hybrid orbitals and a vacant p-orbital. Trivalent (three-coordinate) boron
compounds generally have a trigonal-planar geometry with 120° bond angles
Y. Kubota (B)
Gifu University, Gifu, Japan
e-mail: kubota@gifu-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2021
Y. Ooyama and S. Yagi (eds.), Progress in the Science of Functional Dyes,
https://doi.org/10.1007/978-981-33-4392-4_5
119