absorption maximum of the pristine ligands at 522 nm was found to be split peaks at
548 and 615 nm, due to the exciton coupling [53]. A forbidden peak of Zn(Phenadpm) 2 at 575 nm is attributable to the distinct transition derived from the distorted
formation. To perform chiroptical measurements, chiral HPLC analysis using a
DAICEL CHIRALPAK IE column was performed to purify enantiopure compounds. Figure 5.8b demonstrates the CD spectra of (P,P)-Zn(Phena-dpm) 2 and
(M,M)-Zn(Phena-dpm) 2 in toluene solution. The enantiomers displayed mirrorimage Cotton effects in the UV and visible regions. The value of molar CD Δε in
the visible region (~3000 M
À1 cm
À1 at ca. 500–650 nm) was significantly larger as
compared to than in the UV region (~160 M
À1 cm
À1 at ca. 360 nm). The dissymmetry factors g abs of the P,P form were calculated to be +0.022 (at 360 nm), +0.054
(at 540 nm), and À0.20 (at 615 nm), respectively (Fig. 5.8c) [52].
Then, stable fluorescence spectrum of Zn(Phena-dpm) 2 in the NIR region was
observed (toluene) at 25
C (Fig. 5.8d), together with a good fluorescence quantum
Fig. 5.8 (a) Steady-state absorption spectra of (a) Zn(Phena-dpm) 2 and (b) free Phena-dpm-H. (b)
CD spectra and (c) corresponding dissymmetry factor g abs profiles in toluene. (d) Fluorescence and
(e) CPL spectra of Zn(Phena-dpm) 2 and (f) corresponding dissymmetry factor g lum profiles in
toluene (λ ex ¼ 580 nm). Red and blue lines shows M,M and P,P forms of Zn(Phena-dpm) 2 ,
respectively. The spectra were corrected by a smoothing method (Reprinted with permission
from Ref. [52] Copyright 2018 Wiley-VCH)
110
T. Hasobe
548 and 615 nm, due to the exciton coupling [53]. A forbidden peak of Zn(Phenadpm) 2 at 575 nm is attributable to the distinct transition derived from the distorted
formation. To perform chiroptical measurements, chiral HPLC analysis using a
DAICEL CHIRALPAK IE column was performed to purify enantiopure compounds. Figure 5.8b demonstrates the CD spectra of (P,P)-Zn(Phena-dpm) 2 and
(M,M)-Zn(Phena-dpm) 2 in toluene solution. The enantiomers displayed mirrorimage Cotton effects in the UV and visible regions. The value of molar CD Δε in
the visible region (~3000 M
À1 cm
À1 at ca. 500–650 nm) was significantly larger as
compared to than in the UV region (~160 M
À1 cm
À1 at ca. 360 nm). The dissymmetry factors g abs of the P,P form were calculated to be +0.022 (at 360 nm), +0.054
(at 540 nm), and À0.20 (at 615 nm), respectively (Fig. 5.8c) [52].
Then, stable fluorescence spectrum of Zn(Phena-dpm) 2 in the NIR region was
observed (toluene) at 25
C (Fig. 5.8d), together with a good fluorescence quantum
Fig. 5.8 (a) Steady-state absorption spectra of (a) Zn(Phena-dpm) 2 and (b) free Phena-dpm-H. (b)
CD spectra and (c) corresponding dissymmetry factor g abs profiles in toluene. (d) Fluorescence and
(e) CPL spectra of Zn(Phena-dpm) 2 and (f) corresponding dissymmetry factor g lum profiles in
toluene (λ ex ¼ 580 nm). Red and blue lines shows M,M and P,P forms of Zn(Phena-dpm) 2 ,
respectively. The spectra were corrected by a smoothing method (Reprinted with permission
from Ref. [52] Copyright 2018 Wiley-VCH)
110
T. Hasobe