308
S. Kobatake and T. Nakahama
S
F
F
F
F
F
F
S
O
O
O O
N
N
Me
Me
O
O
O
O
O
O
10a
(Fluorescence ON)
S
F
F
F
F
F
F
S
O
O
O O
N
N
Me
Me
O
O
O
O
O
O
UV
Vis.
10b
(Fluorescence OFF)
(a)
(b)
(c)
(d)
(e)
UV
UV
UV
Vis.
Vis.
Vis.
Time / sec
0
2 0
4 0
6 0
8 0
1 0 0
Time / min
0
2 0
4 0
6 0
8 0 1 0 0 1 2 0
0
0.2
0.4
0.6
0.8
1.0
Fluorescence Intensity
at 568 nm /
a.u.
Dielectric Constant (ε)
0
5
0
0.2
0.4
0.6
0.8
1.0
Relative
ΦF (ΦF/ΦFM)
10
15
20
0
30
60
90
120
150
180
Intensity / 300 msec
Wavelength / nm
300
400
500
600
0
0.2
Absorbance
0.4
0.6
0.8
1.0
Fluorescence Intensity / a.u.
700
UV
UV
UV
Vis.
Vis.
Vis.
532 nm
532 nm
532 nm
532 nm
532 nm
532 nm
532 nm
Fig. 15.7 a Molecular structure of the diarylethene–fluorophore dyad 10a, b absorption and fluorescence spectra of each component of 10 in 1,4-dioxane: absorption spectra of the open-ring
form and closed-ring form of the diarylethene moiety, and absorption and fluorescence spectra of
the fluorophore moiety, c relative fluorescence quantum yields versus the dielectric constant for
10a (open circle) and 10b (closed circle), d change of fluorescence intensities at 568 nm under
excitation at 532 nm of 10a (open circle) and 10b (closed circle) against irradiation time, and
e single-molecule fluorescence photoswitching in a poly(methyl acrylate) (PMA) film containing
10b: sequential wide-field fluorescence images of 10 embedded in the PMA film (upper) and the
corresponding fluorescence intensity trajectory of a single molecule of 10, represented as a white
circle in the upper images. Reprinted with the permission from Ref. [56]. Copyright 2011 American
Chemical Society
suggest that non-destructive fluorescence readout can be realized using dyad 10a.
They have investigated the fluorescence photoswitching and non-destructive fluorescence readout at the single-molecule level. Poly(methyl acrylate) (PMA), which was
selected as a polar and soft polymer, loaded with 10b was prepared. As shown in
Fig. 15.7e, a non-destructive fluorescence readout based on the IET mechanism was
successfully demonstrated even at the single-molecule level. To summarize the results
so far, various attempts on the fluorescence photoswitching using the diarylethenes
have been proposed and demonstrated. Their results will advance the realization of
the ultra-high density optical memory.
S. Kobatake and T. Nakahama
S
F
F
F
F
F
F
S
O
O
O O
N
N
Me
Me
O
O
O
O
O
O
10a
(Fluorescence ON)
S
F
F
F
F
F
F
S
O
O
O O
N
N
Me
Me
O
O
O
O
O
O
UV
Vis.
10b
(Fluorescence OFF)
(a)
(b)
(c)
(d)
(e)
UV
UV
UV
Vis.
Vis.
Vis.
Time / sec
0
2 0
4 0
6 0
8 0
1 0 0
Time / min
0
2 0
4 0
6 0
8 0 1 0 0 1 2 0
0
0.2
0.4
0.6
0.8
1.0
Fluorescence Intensity
at 568 nm /
a.u.
Dielectric Constant (ε)
0
5
0
0.2
0.4
0.6
0.8
1.0
Relative
ΦF (ΦF/ΦFM)
10
15
20
0
30
60
90
120
150
180
Intensity / 300 msec
Wavelength / nm
300
400
500
600
0
0.2
Absorbance
0.4
0.6
0.8
1.0
Fluorescence Intensity / a.u.
700
UV
UV
UV
Vis.
Vis.
Vis.
532 nm
532 nm
532 nm
532 nm
532 nm
532 nm
532 nm
Fig. 15.7 a Molecular structure of the diarylethene–fluorophore dyad 10a, b absorption and fluorescence spectra of each component of 10 in 1,4-dioxane: absorption spectra of the open-ring
form and closed-ring form of the diarylethene moiety, and absorption and fluorescence spectra of
the fluorophore moiety, c relative fluorescence quantum yields versus the dielectric constant for
10a (open circle) and 10b (closed circle), d change of fluorescence intensities at 568 nm under
excitation at 532 nm of 10a (open circle) and 10b (closed circle) against irradiation time, and
e single-molecule fluorescence photoswitching in a poly(methyl acrylate) (PMA) film containing
10b: sequential wide-field fluorescence images of 10 embedded in the PMA film (upper) and the
corresponding fluorescence intensity trajectory of a single molecule of 10, represented as a white
circle in the upper images. Reprinted with the permission from Ref. [56]. Copyright 2011 American
Chemical Society
suggest that non-destructive fluorescence readout can be realized using dyad 10a.
They have investigated the fluorescence photoswitching and non-destructive fluorescence readout at the single-molecule level. Poly(methyl acrylate) (PMA), which was
selected as a polar and soft polymer, loaded with 10b was prepared. As shown in
Fig. 15.7e, a non-destructive fluorescence readout based on the IET mechanism was
successfully demonstrated even at the single-molecule level. To summarize the results
so far, various attempts on the fluorescence photoswitching using the diarylethenes
have been proposed and demonstrated. Their results will advance the realization of
the ultra-high density optical memory.