CD and UV-Vis absorption spectra of (R)-7 [or (S)-7] and (R)-8 [or (S)-8] in
CHCl 3 were acquired (Fig. 2.16a, b, respectively). Several π-πà vibronic UV
transitions in the 315–355 nm range, which are characteristic of the pyrene and
binaphthyl moieties, are clearly observed. The three well-resolved vibronic UV
bands of (R)-7 and (R)-8, which correspond to 0-0
0 (~345 nm), 0-1
0 (~329 nm),
0-2
0 (~315 nm) bands, are observed; these three vibronic bands originate from the
allowed
1 L a transitions of the pyrene moieties in (R)-7 and (R)-8.
The UV-Vis absorption spectra of (R)-7 and (R)-8 are almost identical and their
CD spectra are also similar. The g CD values of the 0-0
0 band of (R)-7 (at 343 nm) and
(R)-8 (at 345 nm) are similar, at only À0.22 Â 10
–4 and À0.67 Â 10
–4 , respectively.
Surprisingly, the CD signals at the 0-0
0 band of (R)-7 and (R)-8 both exhibit negative
0.0
0.5
1.0
1.5
2.0
2.5
3.0
350 400 450 500 550 600
-20
-15
-10
-5
0
5
10
DC / V
CPL / mdeg
Wavelength / nm
Fig. 2.15 CPL (upper) and PL (lower) spectra of (R)-7 (red) and (R)-8 (black) in CHCl 3 (1.0 Â 10
–5
M)
(a)
(b)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
-8
-6
-4
-2
0
2
4
310
340
370
400
Absorbance
CD / mdeg
Wavelength / nm
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
-8
-6
-4
-2
0
2
4
300
350
400
Absorbance
CD / mdeg
Wavelength / nm
Fig. 2.16 CD (upper) and UV-Vis absorption (lower) spectra of (a) (R)-7 (red) and (S)-7 (black
lies) and (b) (R)-8 (red) and (S)-8 (black) in CHCl 3 (1.0 Â 10
–5
M)
22
Y. Imai