Molecules densely packed in the solid state are surrounded by neighboring
molecules. The appearance of solid-state CPL signals may be due to the following
three factors: (1) efficient chirality transfer from the chirally rigid binaphthyl moiety
to the terthiophene units in the solid state; (2) the very limited molecular motion in
the solid state; and (3) efficient photoexcited-state chirality transfer from the
binaphthyl when excited at 297 nm to certain chirally arranged terthiophene units.
In conclusion, unlike in the solution state, solid-state CPL is emitted from axially
chiral binaphthyl fluorophores bearing remote fluorescent units aided by effective
chirality transfer from the axially chiral binaphthyl moiety to the tethered fluorescent
units.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
360 410 460 510 560
-10
-5
0
5
10
DC / V
CPL / mdeg
Wavelength / nm
Fig. 2.24 CPL (upper
panel) and PL (lower panel)
spectra of (R)-10 (red) and
(S)-10 (black) in the KBr
pellet-dispersed state
0.0
0.5
1.0
1.5
2.0
2.5
3.0
-12
-10
-8
-6
-4
-2
0
2
4
6
260 300 340 380 420 460 500
Absorbance
CD / mdeg
Wavelength / nm
-2
-1
0
1
2
320 350 380 410 440
g
e
d
m
/
D
C
Wavelength / nm
Fig. 2.25 CD (upper) and
UV-Vis absorption (lower)
spectra of (R)-10 (red) and
(S)-10 (black) in the KBr
pellet-dispersed state
28
Y. Imai