3.4 Conclusion
In summary, the author described the recent synthetic routes for the optical resolution of di- and tetrasubstituted [2.2]paracyclophane for the development of molecules based on the planar chiral [2.2]paracyclophane molecule that could emit CPL.
Various optically active π-stacked small molecules, oligomers, macrocycles, and
polymers were prepared using the optically active [2.2]paracyclophane as a chiral
building block. It has been suggested that the optically active higher-ordered structures, such as V-, X-, triangle-, and propeller-shaped structures, in the excited state
are important for strong CPL with large g lum values. The results introduced in this
chapter are the first example of application of the optically active [2.2]
paracyclophane molecule in the fields of polymer and materials chemistry. The
π-conjugated molecules based on [2.2]paracyclophane emit luminescence basically
with high Φ PL . Their ε values are large due to the extended π-electron systems,
which lead to the excellent CPL emission. It is difficult to obtain materials that emit
(R p )-18
abs,max = 345 nm
= 0.96 x 10 5 M –1 cm –1
PL,max = 401 nm
PL = 0.81
g lum = +1.3 x 10 –3
OMe
OMe
Br
Br
MeO
OMe
OMe
MeO
OMe
MeO
MeO
OMe
(R p )-16
abs,max = 361 nm
= 0.68 x 10 5 M –1 cm –1
PL,max = 427 nm
PL = 0.75
g lum = –1.7 x 10 –3
350
400
450
500
550
600
650
CPL
PL
Wavelength / nm
350
400
450
500
550
600
650
Wavelength / nm
350
400
450
500
550
600
650
Wavelength / nm
350
400
450
500
550
600
650
Wavelength / nm
(R p )-18
I
L –I
R / a.u.
I
L –I
R / a.u.
Intensity / a.u.
Intensity / a.u.
CPL
PL
(R p )-16
D
D
λ
λ
Φ
λ
λ
Φ
Fig. 3.20 CPL and PL spectra of (R p )-18 and 16 in CHCl 3 (10 Â 10
–5
M)
48
Y. Morisaki