346
Y. Morisaki
Fig. 10.3 Representative examples of oligoaryl-based CPL emitters with axial chirality
Biaryl-based axial chirality is an easily accessible chiral scaffold for
CPL emission. Figure 10.3 shows the binaphthyl-based molecules. In 2007,
perylenebiscarboxydiimide-containing binaphtylene (S)-5 was prepared (Kawai et al.
2007). This compound showed intense emission with Φ PL of 0.88, and the g lum was
estimated to be approximately 3 × 10
−3 . Simple biaryl-based molecules (openand closed-type molecules (S)-6
open and (S)-6
close , respectively) were synthesized
(Kimoto et al. 2012). Despite their similar photoluminescence behavior and identical absolute configuration, these molecules showed different CPL signals. The
values for (S)-6
open and (S)-6
close were calculated to be +1.0 × 10
−3 (Φ PL = 0.19) and
−1.4 × 10
−3 (Φ PL = 0.25), respectively. Optically active naphthalene oligomers were
synthesized; the representative molecule (R,R,R,R,R,R,R)-7 consisting of eight naphthyl moieties is also shown in Fig. 10.3 (Takaishi et al. 2017). This molecule showed
bright CPL emission with g lum = +2.2 × 10
−3 and Φ PL = 0.90. Compound (S)-5
emitted from the perylenediimide moieties, whereas (S)-6 and 7 showed emission
from the oligoaryl scaffolds.
Helical chirality is also employed for CPL emission. Generally, Φ PL of a helical
molecule is not very high; however, its g lum value is very large, often on the order of
10
−2 . Figure 10.4 shows the helicene derivatives (M)-8 (Field et al. 2003) and (M)-9
(Sawada et al. 2012) as representative examples. Molecule 8 is the first helicene
emitting CPL in dilute solution. This molecule was obtained as a diastereomer due
to the attachment of a camphanate unit as the chiral auxiliary. The |g lum | value was
calculated to be 1.1 × 10
−3 . A very large |g lum | value of 3.2 × 10
−2 (Φ PL = 0.30) was
obtained from molecule 9, which was prepared by the Rh-catalyzed enantioselective
[2 + 2 + 2] cycloaddition. Molecule 10 is a stimuli-responsive compound used for
Y. Morisaki
Fig. 10.3 Representative examples of oligoaryl-based CPL emitters with axial chirality
Biaryl-based axial chirality is an easily accessible chiral scaffold for
CPL emission. Figure 10.3 shows the binaphthyl-based molecules. In 2007,
perylenebiscarboxydiimide-containing binaphtylene (S)-5 was prepared (Kawai et al.
2007). This compound showed intense emission with Φ PL of 0.88, and the g lum was
estimated to be approximately 3 × 10
−3 . Simple biaryl-based molecules (openand closed-type molecules (S)-6
open and (S)-6
close , respectively) were synthesized
(Kimoto et al. 2012). Despite their similar photoluminescence behavior and identical absolute configuration, these molecules showed different CPL signals. The
values for (S)-6
open and (S)-6
close were calculated to be +1.0 × 10
−3 (Φ PL = 0.19) and
−1.4 × 10
−3 (Φ PL = 0.25), respectively. Optically active naphthalene oligomers were
synthesized; the representative molecule (R,R,R,R,R,R,R)-7 consisting of eight naphthyl moieties is also shown in Fig. 10.3 (Takaishi et al. 2017). This molecule showed
bright CPL emission with g lum = +2.2 × 10
−3 and Φ PL = 0.90. Compound (S)-5
emitted from the perylenediimide moieties, whereas (S)-6 and 7 showed emission
from the oligoaryl scaffolds.
Helical chirality is also employed for CPL emission. Generally, Φ PL of a helical
molecule is not very high; however, its g lum value is very large, often on the order of
10
−2 . Figure 10.4 shows the helicene derivatives (M)-8 (Field et al. 2003) and (M)-9
(Sawada et al. 2012) as representative examples. Molecule 8 is the first helicene
emitting CPL in dilute solution. This molecule was obtained as a diastereomer due
to the attachment of a camphanate unit as the chiral auxiliary. The |g lum | value was
calculated to be 1.1 × 10
−3 . A very large |g lum | value of 3.2 × 10
−2 (Φ PL = 0.30) was
obtained from molecule 9, which was prepared by the Rh-catalyzed enantioselective
[2 + 2 + 2] cycloaddition. Molecule 10 is a stimuli-responsive compound used for