5 BODIPY Dyes and Their Analogues
163
shows a redshifted λ max and F max , lower ε, and higher Φ f compared with those of
the benzimidazole derivative 78 in solution. Benzothiazole derivative 77 exhibits a
redshifted and higher Φ f compared with benzimidazole derivative 78 in the solidstate. Other type 5 boron diiminate dyes have also been reported (Yamaguchi et al.
2017, 2018; Zhou et al. 2008; Gautam et al. 2019).
For type 6, carbazole-based BODIPY dyes are synthesized by organometallic
approaches such as Suzuki coupling for benzothiazole derivative 79, Pd-catalytic
arylation for benzimidazole derivative 80, cyclization for indolone derivative 81,
and the subsequent boron-complexation (Maeda et al. 2016). Benzothiazole and
benzimidazole derivatives 79 and 80 show fluorescence both in solution and in the
solid-state (Fig. 5.45b). Indolone derivative 81 shows a significantly redshifted λ max
because of the ICT from the carbazole moiety to the indolone moiety. Other type 6
boron diiminate dyes have also been reported (Araneda et al. 2011; Liu et al. 2005a;
Ni et al. 2013; Sun et al. 2015; Más-Montoya et al. 2016; Luo et al. 2016; Maeda
et al. 2019).
For type 7, phenalene-based BF 2 complex 82 has been synthesized by the reaction of 9-(phenylamino)-1H-phenalen-1-one with methylamine in the presence of
trimethyloxonium tetrafluoroborate, followed by boron-complexation (Yan et al.
2014). Phenalene-based BF 2 complexes have AIEE properties (Fig. 5.45c). In the
phenalene-based BF 2 complexes, although the type of substituent R hardly affects
λ max (THF: 491–492 nm), it has a strong influence on Φ f (film: 0.24–0.89).
For type 8, benzo[h]quinoline-based BF 2 complexes have been synthesized by
palladium-catalyzed Hartwig–Buchwald amination of 10-bromobenzo[h]quinoline
with aniline and subsequent boron-complexation (Araneda et al. 2011). 83 has a large
Stokes shift (119 nm) probably because of its unsymmetrical structure (Fig. 5.45d).
Although benzo[h]quinoline-based BF 2 complexes have a relatively low ε (5,800–
9,100), they show a relatively high Φ f (0.60–0.66).
For type 9, quino[7,8-h]quinoline-based BF 2 complex with tetrafluoroborate
counter ion 84 have been reported by the reaction of quino[7,8-h]quinoline with
boron trifluoride diethyl etherate (Shaffer et al. 2012). 84 shows λ max at 382 nm and
does not show fluorescence (Fig. 5.45e). Other type 9 boron diiminate dyes have also
been reported (Zeng et al. 2011).
5.2.4.3 Other
6 NˆN Monoboron Complexes
A part of other examples of six-membered ring NˆN (
6 NˆN) type monoboron
complexes is shown in Fig. 5.46. Boron 2-picolinoylpyrrole complex (BOPPY
(Ito et al. 2007)) shows blueshifted λ max compared with those of BODIPY dyes
(Fig. 5.46a). BOPPY has a large Stokes shift, whereas the Φ f is very low. Although
the λ max of BOPPY is blueshifted with increasing solvent polarity, the F max is shifted
to red with increasing solvent polarity.
Amidine-based BF 2 complex 85 (Φ f < 0.01) hardly shows fluorescence in DCM,
whereas it shows enhanced fluorescence in the solid-state (Φ f = 0.22) because of the
163
shows a redshifted λ max and F max , lower ε, and higher Φ f compared with those of
the benzimidazole derivative 78 in solution. Benzothiazole derivative 77 exhibits a
redshifted and higher Φ f compared with benzimidazole derivative 78 in the solidstate. Other type 5 boron diiminate dyes have also been reported (Yamaguchi et al.
2017, 2018; Zhou et al. 2008; Gautam et al. 2019).
For type 6, carbazole-based BODIPY dyes are synthesized by organometallic
approaches such as Suzuki coupling for benzothiazole derivative 79, Pd-catalytic
arylation for benzimidazole derivative 80, cyclization for indolone derivative 81,
and the subsequent boron-complexation (Maeda et al. 2016). Benzothiazole and
benzimidazole derivatives 79 and 80 show fluorescence both in solution and in the
solid-state (Fig. 5.45b). Indolone derivative 81 shows a significantly redshifted λ max
because of the ICT from the carbazole moiety to the indolone moiety. Other type 6
boron diiminate dyes have also been reported (Araneda et al. 2011; Liu et al. 2005a;
Ni et al. 2013; Sun et al. 2015; Más-Montoya et al. 2016; Luo et al. 2016; Maeda
et al. 2019).
For type 7, phenalene-based BF 2 complex 82 has been synthesized by the reaction of 9-(phenylamino)-1H-phenalen-1-one with methylamine in the presence of
trimethyloxonium tetrafluoroborate, followed by boron-complexation (Yan et al.
2014). Phenalene-based BF 2 complexes have AIEE properties (Fig. 5.45c). In the
phenalene-based BF 2 complexes, although the type of substituent R hardly affects
λ max (THF: 491–492 nm), it has a strong influence on Φ f (film: 0.24–0.89).
For type 8, benzo[h]quinoline-based BF 2 complexes have been synthesized by
palladium-catalyzed Hartwig–Buchwald amination of 10-bromobenzo[h]quinoline
with aniline and subsequent boron-complexation (Araneda et al. 2011). 83 has a large
Stokes shift (119 nm) probably because of its unsymmetrical structure (Fig. 5.45d).
Although benzo[h]quinoline-based BF 2 complexes have a relatively low ε (5,800–
9,100), they show a relatively high Φ f (0.60–0.66).
For type 9, quino[7,8-h]quinoline-based BF 2 complex with tetrafluoroborate
counter ion 84 have been reported by the reaction of quino[7,8-h]quinoline with
boron trifluoride diethyl etherate (Shaffer et al. 2012). 84 shows λ max at 382 nm and
does not show fluorescence (Fig. 5.45e). Other type 9 boron diiminate dyes have also
been reported (Zeng et al. 2011).
5.2.4.3 Other
6 NˆN Monoboron Complexes
A part of other examples of six-membered ring NˆN (
6 NˆN) type monoboron
complexes is shown in Fig. 5.46. Boron 2-picolinoylpyrrole complex (BOPPY
(Ito et al. 2007)) shows blueshifted λ max compared with those of BODIPY dyes
(Fig. 5.46a). BOPPY has a large Stokes shift, whereas the Φ f is very low. Although
the λ max of BOPPY is blueshifted with increasing solvent polarity, the F max is shifted
to red with increasing solvent polarity.
Amidine-based BF 2 complex 85 (Φ f < 0.01) hardly shows fluorescence in DCM,
whereas it shows enhanced fluorescence in the solid-state (Φ f = 0.22) because of the