emission peaks at 580 (
5 D 0 !
7 F 0 ), 595 (
5 D 0 !
7 F 1 ), and 620 nm (
5 D 0 !
7 F 2 ).
Meanwhile, mirror-image CPL signals were obtained for the enantiomer pair of 3o
complexes at the bands of
5
D 0 !
7 F 1 and
5 D 0 !
7 F 2 transitions corresponding to
magnetic and electronic dipole ones, respectively (Fig. 8.11b). The emergence of
CPL signals clearly suggested the induction of optical activity in the dinuclear Eu
(III) complexes. We obtained |g lum | values of 0.1 at the magnetic-dipole transition
band, which are ten times larger than that of the pyrene-containing 2o. The enantiomeric enrichment in the Eu(III)-complex sites was further confirmed with the
induction of CD signal in the f-f transition absorption bands by replacing Eu(III) ions
with Nd(III) ions (3o(Nd)). The mirror-image CD spectra over 500 nm
corresponding to the f-f transition region in Nd(III) ion clearly support that the
chirality is indeed induced as a coordination chirality in the local Ln(III) complex
sites.
To further discuss the origin of optical activity, tta ligand in 3o were replaced
with a number of β-diketonato ligands both with symmetric and asymmetric structures. The Eu(III) complexes with asymmetric β-diketonato ligands having a
trifluoromethyl (CF 3 ) and aromatic units showed much better photoluminescence
and CPL efficiency compared with those with symmetric β-diketonato ligands. This
result further confirms that the enriched population of an enantiomeric coordination
N
N
N
O
CF 3
O
NH
O
S
N
S
N
N
S
S
N
HN
HN
O
O
NH
O
Ph
Ph
N
N
N
O
O
3
Eu III
Eu III
3
S
CF 3
S
S
N
S
N
S
N
N
S
HN
HN
O
NH
O
O
NH
O
N
N
N
N
N
N
Eu
III
O
CF 3
O
Eu
III
O
CF 3
O
Ph
Ph
3
3
S
S
UV
vis
D-3o
D-3c
Fig. 8.10 Photo-switching reaction of D-3
8 Photo-Switching of Circularly Polarized Luminescence
185
5 D 0 !
7 F 0 ), 595 (
5 D 0 !
7 F 1 ), and 620 nm (
5 D 0 !
7 F 2 ).
Meanwhile, mirror-image CPL signals were obtained for the enantiomer pair of 3o
complexes at the bands of
5
D 0 !
7 F 1 and
5 D 0 !
7 F 2 transitions corresponding to
magnetic and electronic dipole ones, respectively (Fig. 8.11b). The emergence of
CPL signals clearly suggested the induction of optical activity in the dinuclear Eu
(III) complexes. We obtained |g lum | values of 0.1 at the magnetic-dipole transition
band, which are ten times larger than that of the pyrene-containing 2o. The enantiomeric enrichment in the Eu(III)-complex sites was further confirmed with the
induction of CD signal in the f-f transition absorption bands by replacing Eu(III) ions
with Nd(III) ions (3o(Nd)). The mirror-image CD spectra over 500 nm
corresponding to the f-f transition region in Nd(III) ion clearly support that the
chirality is indeed induced as a coordination chirality in the local Ln(III) complex
sites.
To further discuss the origin of optical activity, tta ligand in 3o were replaced
with a number of β-diketonato ligands both with symmetric and asymmetric structures. The Eu(III) complexes with asymmetric β-diketonato ligands having a
trifluoromethyl (CF 3 ) and aromatic units showed much better photoluminescence
and CPL efficiency compared with those with symmetric β-diketonato ligands. This
result further confirms that the enriched population of an enantiomeric coordination
N
N
N
O
CF 3
O
NH
O
S
N
S
N
N
S
S
N
HN
HN
O
O
NH
O
Ph
Ph
N
N
N
O
O
3
Eu III
Eu III
3
S
CF 3
S
S
N
S
N
S
N
N
S
HN
HN
O
NH
O
O
NH
O
N
N
N
N
N
N
Eu
III
O
CF 3
O
Eu
III
O
CF 3
O
Ph
Ph
3
3
S
S
UV
vis
D-3o
D-3c
Fig. 8.10 Photo-switching reaction of D-3
8 Photo-Switching of Circularly Polarized Luminescence
185