positive 340-nm CD, and 310-nm positive peaks, which are all mirror images for
(P)3 [6]CH
à . In the transient absorption spectrum, only two absorption bands may be
identified, whereas each CD spectrum clearly shows four distinct transitions. It
should be noted that these TRCD spectra shown here are essentially the same as
those in the previous report for the 600–700 nm range, which demonstrates the
validity of our measurement [26].
The observed temporal changes of ΔS(t) are shown in Fig. 15.6 (upper panel), in
which the decay of the positive region is seen for (P)3 [6]CH
à with a half-decay time
of ca. 10 μs, while the decay in the negative region is seen for (M)3 [6]CH
à as the
mirror image with almost the same half-decay time.
We have reached the conclusion that we have successfully observed the CD
spectrum of
3 [6]CH
à in solution by means of TRCD spectroscopy. The CD spectrum
of (P)3 [6]CH
à in 600–700 nm has positive Cotton effects, while (M )3 [6]CH
Ã
exhibits negative effects with the same spectral shape, one of the most distinguishing
characteristics of the CD spectrum. Our experimentally observed CD spectrum in
solution was almost identical to the previously reported CD spectrum carefully
evaluated under the photo-stationary state of [6]CH derivatives in the frozen
media, which means our observation has reached the criteria of validation.
We hope such information may be helpful in developing circularly polarized
light-emitting devices. Furthermore, electronic interaction between chromophores in
chiral orientation is given by CD spectroscopy from the analysis of the exciton
Fig. 15.6 (a) Time-profile
of ΔS of (P)3
[6]CH
à (light
red dot) and (M )3
[6]CH
Ã
(light blue dot) in toluene at
RT monitored at 632 nm
from He–Ne laser as a stable
monitor light, which was
detected with
photomultiplier tubes after
passing Gran-laser prism,
retarder, and quartz cell.
Azimuth of retarder θ ¼ 15
.
Solid red and blue lines;
fitting curves. (b) ΔAbsdecay of
3
[6]CH
à at 632 nm.
Orange solid line; fitting
curve (reprinted from
Kuronuma et al. [11])
15 Transient Circular Dichroism Approach to Chirality Detection in Dark. . .
337
(P)3 [6]CH
à . In the transient absorption spectrum, only two absorption bands may be
identified, whereas each CD spectrum clearly shows four distinct transitions. It
should be noted that these TRCD spectra shown here are essentially the same as
those in the previous report for the 600–700 nm range, which demonstrates the
validity of our measurement [26].
The observed temporal changes of ΔS(t) are shown in Fig. 15.6 (upper panel), in
which the decay of the positive region is seen for (P)3 [6]CH
à with a half-decay time
of ca. 10 μs, while the decay in the negative region is seen for (M)3 [6]CH
à as the
mirror image with almost the same half-decay time.
We have reached the conclusion that we have successfully observed the CD
spectrum of
3 [6]CH
à in solution by means of TRCD spectroscopy. The CD spectrum
of (P)3 [6]CH
à in 600–700 nm has positive Cotton effects, while (M )3 [6]CH
Ã
exhibits negative effects with the same spectral shape, one of the most distinguishing
characteristics of the CD spectrum. Our experimentally observed CD spectrum in
solution was almost identical to the previously reported CD spectrum carefully
evaluated under the photo-stationary state of [6]CH derivatives in the frozen
media, which means our observation has reached the criteria of validation.
We hope such information may be helpful in developing circularly polarized
light-emitting devices. Furthermore, electronic interaction between chromophores in
chiral orientation is given by CD spectroscopy from the analysis of the exciton
Fig. 15.6 (a) Time-profile
of ΔS of (P)3
[6]CH
à (light
red dot) and (M )3
[6]CH
Ã
(light blue dot) in toluene at
RT monitored at 632 nm
from He–Ne laser as a stable
monitor light, which was
detected with
photomultiplier tubes after
passing Gran-laser prism,
retarder, and quartz cell.
Azimuth of retarder θ ¼ 15
.
Solid red and blue lines;
fitting curves. (b) ΔAbsdecay of
3
[6]CH
à at 632 nm.
Orange solid line; fitting
curve (reprinted from
Kuronuma et al. [11])
15 Transient Circular Dichroism Approach to Chirality Detection in Dark. . .
337