(R p )-1-3 occurred from the chromophore state rather than from the phane state [40–
44]. CPL spectra for (R p )-1-3 and (S p )-1-3 in dilute CHCl 3 (1.0 Â 10
–5 M) were
obtained. Intense CPL signals of I L À I R , where I L and I R are the intensities of leftand right-handed PL, respectively, were obtained. The CPL signals of the two
compounds were the mirror images of each other. Interestingly, the CPL dissymmetry factors g lum ¼ 2(I L À I R )/(I L + I R ) increased gradually with increasing number
of the stacked π-electron systems. This result suggests the emergence of additional
chirality, besides the planar chirality of the [2.2]paracyclophane skeleton.
Figure 3.11b shows the PL and CPL spectra of the linear trimer 2 (N-shaped
molecule) and cyclic trimer 4 (chiral triangle-shaped molecule). Molecules 2 and
4 exhibited identical PL and CPL profiles. The cyclic trimer has chiral triangleshaped chirality, i.e., a chiral second-ordered structure, in addition to the planar
chirality of the [2.2]paracyclophane skeleton. Considering the identical CPL profiles
between the linear and cyclic trimers, linear trimer 2 should form the chiral secondordered structure as the additional chirality in addition to the planar chirality. It is
suggested that a one-handed helical structure (left-handed helix for (R p )-isomer) is
formed in the excited stated of linear trimer 2, as shown in Fig. 3.12.
4,7,12,15-Tetraethynyl[2.2]paracyclophane was prepared from 4,7,12-Tribromo15-trifluoremethanesulfonyl[2.2]paracyclophane (Fig. 3.13), followed by the synthesis of the optically active cyclic molecule 5 [35]. The optically active molecule
5 formed the chiral second-ordered structure such as one-handed propeller-shaped
C 12 H 25 O
OC 12 H 25
OC 12 H 25
C 12 H 25 O
C 12 H 25 O
OC 12 H 25
OC 12 H 25
C 12 H 25 O
C 12 H 25 O
OC 12 H 25
(R p )-1
(R p )-2
C 12 H 25 O
OC 12 H 25
OC 12 H 25
C 12 H 25 O
C 12 H 25 O
OC 12 H 25
C 12 H 25 O
OC 12 H 25
OC 12 H 25
C 12 H 25 O
C 12 H 25 O
OC 12 H 25
OC 12 H 25
C 12 H 25 O
(R p )-3
(R p )-4
Fig. 3.10 Optically active V-, N-, and W-shaped π-stacked molecules
3 Circularly Polarized Luminescence from Planar Chiral Compounds Based on. . .
39
44]. CPL spectra for (R p )-1-3 and (S p )-1-3 in dilute CHCl 3 (1.0 Â 10
–5 M) were
obtained. Intense CPL signals of I L À I R , where I L and I R are the intensities of leftand right-handed PL, respectively, were obtained. The CPL signals of the two
compounds were the mirror images of each other. Interestingly, the CPL dissymmetry factors g lum ¼ 2(I L À I R )/(I L + I R ) increased gradually with increasing number
of the stacked π-electron systems. This result suggests the emergence of additional
chirality, besides the planar chirality of the [2.2]paracyclophane skeleton.
Figure 3.11b shows the PL and CPL spectra of the linear trimer 2 (N-shaped
molecule) and cyclic trimer 4 (chiral triangle-shaped molecule). Molecules 2 and
4 exhibited identical PL and CPL profiles. The cyclic trimer has chiral triangleshaped chirality, i.e., a chiral second-ordered structure, in addition to the planar
chirality of the [2.2]paracyclophane skeleton. Considering the identical CPL profiles
between the linear and cyclic trimers, linear trimer 2 should form the chiral secondordered structure as the additional chirality in addition to the planar chirality. It is
suggested that a one-handed helical structure (left-handed helix for (R p )-isomer) is
formed in the excited stated of linear trimer 2, as shown in Fig. 3.12.
4,7,12,15-Tetraethynyl[2.2]paracyclophane was prepared from 4,7,12-Tribromo15-trifluoremethanesulfonyl[2.2]paracyclophane (Fig. 3.13), followed by the synthesis of the optically active cyclic molecule 5 [35]. The optically active molecule
5 formed the chiral second-ordered structure such as one-handed propeller-shaped
C 12 H 25 O
OC 12 H 25
OC 12 H 25
C 12 H 25 O
C 12 H 25 O
OC 12 H 25
OC 12 H 25
C 12 H 25 O
C 12 H 25 O
OC 12 H 25
(R p )-1
(R p )-2
C 12 H 25 O
OC 12 H 25
OC 12 H 25
C 12 H 25 O
C 12 H 25 O
OC 12 H 25
C 12 H 25 O
OC 12 H 25
OC 12 H 25
C 12 H 25 O
C 12 H 25 O
OC 12 H 25
OC 12 H 25
C 12 H 25 O
(R p )-3
(R p )-4
Fig. 3.10 Optically active V-, N-, and W-shaped π-stacked molecules
3 Circularly Polarized Luminescence from Planar Chiral Compounds Based on. . .
39