Benzothiadiazole-based dyes that emit red light in solution, solid, and liquid state

Article abstract of DOI:10.1016/j.tet.2013.08.066

In this paper, we report the preparation and red-light-emitting behavior of benzothiadiazole-tris(alkyloxy)phenylethene dyes. In solution, we observed an efficient red light emission with high fluorescence quantum yields (up to 0.78). With increase in solvent polarity, the emission bands shifted to longer wavelengths accompanied by a large Stokes shift of up to 152 nm. A moderate fluorescence quantum yield of 0.52 could be achieved even in the polar solvent dimethylformamide. Red light emission with good fluorescence quantum yields (up to 0.50) was also observed in the bulk solid, liquid, and film state.

Full text of DOI:10.1016/j.tet.2013.08.066

Tetrahedron 69 (2013) 9475e9480
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Benzothiadiazole-based dyes that emit red light in solution, solid,
and liquid state
*
Tsutomu Ishi-i , Miki Sakai, Chihiro Shinoda
Department of Biochemistry and Applied Chemistry, Kurume National College of Technology, 1-1-1 Komorino, Kurume 830-8555, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 22 July 2013
Received in revised form 21 August 2013
Accepted 24 August 2013
Available online 30 August 2013
In this paper, we report the preparation and red-light-emitting behavior of benzothiadiazolee-
tris(alkyloxy)phenylethene dyes. In solution, we observed an efficient red light emission with high
fluorescence quantum yields (up to 0.78). With increase in solvent polarity, the emission bands shifted to
longer wavelengths accompanied by a large Stokes shift of up to 152 nm. A moderate fluorescence
quantum yield of 0.52 could be achieved even in the polar solvent dimethylformamide. Red light
emission with good fluorescence quantum yields (up to 0.50) was also observed in the bulk solid, liquid,
and film state.
Keywords:
Red light emission
Solid-state fluorescence
Liquid-state fluorescence
Benzothiadiazoles
Donoreacceptor
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
phenylethene, in a benzothiadiazole-based dye to produce efficient
red light emission in nonpolar and polar solutions as well as in the
In recent years, light-emitting dyes have been of much interest
in view of their applications in material sciences (e.g., organic light-
emitting diodes) and in biological sciences (e.g., bioprobes and
biosensors).1 Developing red-light-emitting material is very im-
portant because red is one of the three primary colors, and also
because red light falls within the biological optical window. Thus,
a high emission efficiency is desirable both in solution and in the
bulk solid. Till date, a number of red emitting dyes have been re-
bulk solid, film, and liquid state. We have used tris(alkyloxy)phe-
nylethene as the donor because the three alkyloxy groups behave as
electron-donating groups. In addition, the ethylene moiety is
,2
a versatile spacer that can be used to expand the
system.
p-electron
12
2. Results and discussion
3
4
ported. For example, boronedipyrromethenes and perylene dii-
mides5 are known as superior red-light-emitting dyes. However,
these dyes exhibit a small Stokes shift, which results in the re-
absorption of the emitted light. A simple strategy for obtaining
red light emission is donoreacceptor conjugation, which results in
the shifting of the emission band to longer wavelengths. This is
Benzothiadiazole dyes 3aec having two tris(alkyloxy)phenyl-
ethene moieties were prepared from the coupling reactions of
dibromobenzothiadiazole 1 with the corresponding tris(alkyloxy)
phenylethenes 2aec in the presence of a palladium catalyst
(
Scheme 1). The synthetic intermediates 2aec were prepared by
6
accompanied by a large Stokes shift.
13
methods described previously. The obtained dyes 3aec were
identified using spectroscopic methods and elemental analysis.
The dyes 3a and 3b bearing methoxy groups and octyloxy
groups, respectively, are red solids. With an increase in the alkyl
chain length, the melting temperature decreased from 238e240 C
for 3a to 66e68 C for 3b. The melting temperature of dye 3c, which
Benzothiadiazole dyes are strongly fluorescent both in solution
7,8
and in the bulk solid. In addition, the dyes are strongly electron-
accepting.9 Recently, we reported that benzothiadiazole dyes,
10
which contain electron-donating triphenylamines emit red light.
ꢀ
However, in polar solutions, the red emission is quenched by sol-
vation of the polar molecules, and this reduces the emission effi-
ciency.11 Herein, we report the use of a novel donor, tris(alkyloxy)
ꢀ
bears branched 2-ethylhexyloxy groups, decreased below the am-
bient temperature; consequently, 3c was a red viscous liquid.
The dyes 3aec were soluble in common organic solvents, such
as toluene, tetrahydrofuran (THF), and dichloromethane (DCM).
The dye 3a, bearing short alkyl chains, tended to dissolve in polar
solvents, such as dimethylformamide (DMF), whereas 3b and 3c,
*
Corresponding author. Tel.: þ81 942 35 9404; fax: þ81 942 35 9400; e-mail
address: ishi-i@kurume-nct.ac.jp (T. Ishi-i).
0
040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.08.066

9476
T. Ishi-i et al. / Tetrahedron 69 (2013) 9475e9480
(
(
(
(
a)
0
0
0
0
.4
.3
.2
.1
0
toluene
THF
DCM
DMF
ε
300
400
500
600
Wavelength (nm)
b)
c)
d)
toluene
THF
DCM
DMF
5
00
600
700
800
800
800
Wavelength (nm)
hexane
toluene
THF
Scheme 1. Preparation of benzothiadiazole-based dyes 3aec.
DCM
bearing long alkyl chains, tended to dissolve in nonpolar solvents,
such as hexane.
The UVevis and fluorescence spectra were measured in various
solvents (from nonpolar to polar solvents) to investigate the in-
fluence of solvent polarity on the optical properties of the benzo-
thiadiazole dyes (Fig. 1 and Table 1). The UVevis spectra of 3a, 3b,
and 3c show absorption bands at around 469e474, 474e478, and
500
600
700
Wavelength (nm)
hexane
toluene
THF
4
75e479 nm, respectively. These bands would be attributed to the
transition of the electron from the electron-donating tris(alkyloxy)
phenylethene moiety to the electron-accepting benzothiadiazole
moiety (Fig. 1a and Table 1). The absorption bands shifted very
slightly depending on the solvent polarity (hexane, toluene, THF,
DCM, and DMF). The very weak absorption solvatochromism in-
dicates that the weakly polarized ground state is stabilized in polar
solvent media.
Strong light emission was observed in 3aec (Fig. 1bed). The
emission bands shifted to longer wavelengths with an increase in
the solvent polarity: from 590 nm (toluene) to 624 nm (DMF) in 3a,
from 575 nm (hexane) to 621 nm (DCM) in 3b, and from 575 nm
DCM
5
00
600
700
Wavelength (nm)
(
hexane) to 622 nm (DCM) in 3c (Table 1). The wavenumber of the
emission bands showed a good correlation with the solvent polarity
ꢂ5
Fig. 1. (a) UVevis spectra of 3a at 1ꢁ10 M. Fluorescence spectra of (b) 3a, (c) 3b, and,
parameters14 ðE Þ of the various solvents (Fig. 2). The bathochromic
N
ꢂ6
(d) 3c in 1ꢁ10 M in hexane, toluene, THF, DCM, and DMF excited at 470 nm (3a) and
T
475 nm (3b and 3c).
shift in the fluorescence solvatochromism is attributed to the
donoreacceptor character of the dye arising from the electron-
accepting benzothiadiazole moiety and the electron-donating tri-
s(alkyloxy)phenylethene moieties. In the polar solvent media, the
stabilization of the polarized excited state arising from the
donoreacceptor character resulted in the lowering of energy levels
and the bathochromic shift. As a result of the bathochromic shift,
a large Stokes shift occurred (up to 152 nm in DMF for 3a). In the

T. Ishi-i et al. / Tetrahedron 69 (2013) 9475e9480
9477
Table 1
Spectral data of 3a, 3b, and 3c
c
Compd
Solvent
Toluene
l
max
3
l
ex
l
FL
F
FL
Dl
(nm)
a
b
(
nm)
(nm)
470
(nm)
590
3a
474
24,540
0.76
.77
0.72
0.70
.69
116
d
d
0
THF
DCM
474
469
27,480
26,890
470
470
601
613
127
144
0
DMF
Solid
Hexane
472
474
24,430
27,740
470
470
475
624
629
575
0.52
152
101
0.44d
0.78
3b
e
5
5
79
98f
Toluene
478
26,710
475
592
0.75
114
d
0.76
THF
DCM
478
474
28,650
28,330
475
475
605
621
0.71
0.67
127
147
d
d
0.69
Solid
Film
Hexane
475
475
475
618
610
575
0.50
478
475
0.31d
0.75
132
100
Fig. 3. Fluorescence images of (a) 3a in toluene, THF, DCM, and DMF (from left to
right), (b) 3a in the bulk solid, (c) 3b in the film, and (d) 3c in the bulk liquid under UV
3c
29,030
27,310
e
5
5
80
light irradiation. The values in the image are fluorescence quantum yields (FFL).
98f
Toluene
477
475
596
0.71
119
d
0.72
THF
DCM
Liquid
479
475
485
28,040
28,000
475
475
475
608
622
623
0.66
129
147
138
Red light emission is also observable in the bulk state (Figs.
3bed and 4). In the solid state, the emission bands were observed at
0.60
0.12d
6
29 nm (
for 3b. A similar emission was observed at 610 nm (
0.31) in the film state of 3b. Interestingly, the red light emission at
623 nm ( FL value of 0.12) could be observed in the liquid state of
c. These results indicate that these emitting dyes could be used as
light-emitting materials both in liquid and in dry-solid systems,
F
FL value of 0.44) for 3a, and at 618 nm (
F
FL value of 0.50)
a
b
c
ꢂ5
1
1
ꢁ10 M.
ꢂ6
F
FL value of
ꢁ10 M.
Fluorescence quantum yield (FFL) relative to fluorescein in ethanol (0.97, ex.
4
55 nm).
F
d
Absolute fluorescence quantum yield (
F
FL).
3
e
f
ꢂ3
1
1
ꢁ10 M.
ꢂ2
ꢁ10 M.
15
such as organic light-emitting diodes.
1
.74
3a
3b
3c
3
3
3
3
a (solid)
b (solid)
b (film)
1
.7
1.66
1.62
1.58
c (liquid)
0
0.1
0.2
T
0.3
0.4
N
E
550
600
650
Wavelength (nm)
700
750
Fig. 2. Correlation of the emission band wavenumber with solvent polarity parameters
ðET Þ: correlation coefficient: 0.998 for 3a, 0.995 for 3b, and 0.984 for 3c.
N
Fig. 4. Fluorescence spectra of 3a, 3b, and 3c in the bulk solid, liquid, and film state
excited at 470 nm (3a) and 475 nm (3b and 3c).
polar solvents DCM and DMF, red light could be emitted with high
fluorescence quantum yields (FFL) (Fig. 3a and Table 1). The F
FL
values 0.70 (3a), 0.67 (3b), and 0.60 (3c) in DCM are higher than
that (0.36) of the benzothiadiazole derivative bearing the triphe-
nylamine donor moiety. In addition, a high FFL value of 0.52 in 3a
In the bulk state, the emission bands for 3b (610e618 nm) and
10
3
(
c (623 nm) were observed at longer wavelengths relative to those
can be achieved in the more polar solvent DMF. In the polarized
excited state, the positive charge may be delocalized among the
donor moieties, including the three oxygen atoms, resulting in
disturbance of the significant solvation quenching in polar solvent
media.
ꢂ6
575 nm) observed in hexane (1ꢁ10 M). The bathochromic shift is
attributed to the aggregation of the 3b and 3c molecules. The
concentration dependence of the fluorescence spectra in hexane is
16
supportive of the aggregation. At higher concentrations, the
emission band of 3b shifted to longer wavelengths (from 575 to
In general, the
FFL values of 3b, bearing long alkyl chains, are
5
98 nm) because of facilitated aggregation. The emission band at
lower than that of 3a, bearing short alkyl chains. In addition, the
F
FL
ꢂ2
the higher concentration (1ꢁ10 M) shows good agreement with
those of the bulk film and solid states (Fig. 5). We observed a similar
trend for the concentration-dependent fluorescence spectra of 3c
values are reduced in 3c bearing branched alkyl chains (Table 1).
These results indicate that the emission efficiency is affected by the
length and the branching of the alkyl chains.
(
Table 1).

9478
T. Ishi-i et al. / Tetrahedron 69 (2013) 9475e9480
measurements of absolute fluorescence quantum yields was pre-
1
1
1
1
x 10-2 M
x 10-3 M
x 10-4 M
x 10-6 M
pared by drop casting and the subsequent spin-coating (2000 rpm,
ꢂ3
30 s) from a 1.0ꢁ10 M hexane solution (20
mLꢁ3) on quartz cell
(12.5ꢁ12.5ꢁ15 mm).
4.4. 4,7-Bis[2-(3,4,5-trimethoxyphenyl)ethenyl]-2,1,3-
film
benzothiadiazole (3a)
To a suspension of 1 (147 mg, 0.5 mmol), 2a (204 mg,
1.05 mmol), and triethylamine (0.70 mL, 5 mmol) in dry DMF
(10 mL) was added a solution of palladium acetate (11.2 mg,
0
.05 mmol) and tri(o-tolyl)phosphine (31 mg, 0.1 mmol) in dry
ꢀ
500
600
700
800
DMF (2.5 mL) at 100 C under an argon atmosphere, and the mix-
ture was allowed to stand for 15 h. After the reaction mixture was
cooled to 0 C, it was quenched with aqueous 1.2 N hydrochloric
Wavelength (nm)
ꢀ
Fig. 5. Fluorescence spectra of 3b in hexane (1ꢁ10ꢂ6, 1ꢁ10ꢂ4, 1ꢁ10ꢂ3, and 1ꢁ10ꢂ2 M)
and in the film state excited at 475 nm.
acid solution and extracted with dichloromethane. The organic
layer was washed with brine sufficiently, dried over anhydrous
magnesium sulfate, and evaporated in vacuo to dryness. The resi-
due was purified by silica gel column chromatography (WAKO
C300) eluting with chloroform and by recrystallization from
dichloromethane/hexane to give 3a in 45% yield (118 mg,
3
. Conclusion
In conclusion, we have demonstrated that red-light-emitting
ꢀ
ꢂ1
0.227 mmol): reddish orange solid; mp 238e240 C; IR (KBr, cm
)
systems could be created by a combination of benzothiadiazole
with tris(alkyloxy)phenylethene moieties. The present results
provide useful information for strategies on using red-light-
emitting material in solution (nonpolar and polar) state as well as
in the bulk state (solid and liquid).
3
028, 2989, 2934, 2838, 1579, 1509, 1450, 1417, 1341, 1327, 1243,
1
1132, 994, 966, 835, 655; H NMR (CDCl
3 3
) d 3.91 (s, 6H, CH ), 3.96 (s,
1
2H, CH
3
), 6.88 (s, 4H, ArH), 7.54 (d, J¼16.3 Hz, 2H, olefinic H), 7.69
13
(
d
s, 2H, ArH), 7.97 (d, J¼16.3 Hz, 2H, olefinic H); C NMR (CDCl
3
)
56.21, 61.01, 104.02, 123.95, 127.05, 129.20, 133.19, 133.32, 138.52,
þ
153.48, 153.93; FAB-MS (positive, NBA) m/z 520 (M ). Anal. Calcd
4
4
. Experimental
for C28
H
28
N
2
O
6
S (520.60): C, 64.60; H, 5.42; N, 5.38. Found: C,
6
4.36; H, 5.41; N, 5.38.
.1. General
4
.5. 4,7-Bis{2-[3,4,5-tris(octyloxy)phenyl]ethenyl}-2,1,3-
All melting points are uncorrected. IR spectra were recorded on
benzothiadiazole (3b)
a JASCO FT/IR-470 plus Fourier transform infrared spectrometer
1
13
and measured as KBr pellets and on NaCl plate. H and C NMR
spectra were determined in CDCl with a JEOL JNM-LA 400 spec-
trometer. Residual solvent protons and carbons were used as in-
ternal standard and chemical shifts ( ) are given relative to
To a suspension of 1 (59 mg, 0.2 mmol), 2b (203 mg, 0.42 mmol),
and triethylamine (0.28 mL, 2.0 mmol) in dry DMF (2 mL) was
added a solution of palladium acetate (4.4 mg, 0.02 mmol) and
3
d
tri(o-tolyl)phosphine (12 mg, 0.04 mmol) in dry DMF (1 mL) at
tetramethylsilane (TMS). The coupling constants (J) are reported in
hertz (Hz). Elemental analysis was performed at the Elemental
Analytical Center, Kyushu University. Fast atom bombardment mass
spectrometry (FAB-MS) spectra were recorded with a JEOL JMS-70
mass spectrometer with m-nitrobenzyl alcohol (NBA) as a matrix.
Analytical TLC was carried out on silica gel coated on aluminum foil
Merck 60F254). Column chromatography was carried out on silica
gel (WAKO C300 and KANTO 60N). Gel permeation chromatogra-
phy (GPC) was performed using a Japan Analytical Industry Co., Ltd
ꢀ
100 C under an argon atmosphere, and the mixture was allowed to
ꢀ
stand for 15 h. After the reaction mixture was cooled to 0 C, it was
quenched with aqueous 1.2 N hydrochloric acid solution and
extracted with dichloromethane. The organic layer was washed
with brine sufficiently, dried over anhydrous magnesium sulfate,
and evaporated in vacuo to dryness. The residue was purified by
silica gel column chromatography (WAKO C300) eluting with
hexane/dichloromethane (2:1, v/v) and by GPC eluting with chlo-
roform to give 3b in 64% yield (141 mg, 0.127 mmol): reddish or-
(
LC-918 with
a
combination of JAIGEL-1H and JAIGEL-2H
ꢀ
ꢂ1
ange solid; mp 66e68 C; IR (KBr, cm ) 3034, 2952, 2922, 2851,
626, 1577, 1505, 1467, 1432, 1389, 1341, 1283, 1243, 1119, 964, 899,
ꢂ1
(
20ꢁ600 mm) columns eluting with chloroform (3.0 mL min ).
1
Compounds 2a and 2b were prepared according to methods re-
1
8
32, 722, 653; H NMR (CDCl
.22e1.42 (m, 48H, CH ), 1.45e1.56 (m, 12H, ArOCH
quint, J¼6.8 Hz, 4H, ArOCH CH ), 1.85 (quint, J¼6.8 Hz, 8H,
ArOCH CH ), 4.06 (t, J¼6.8 Hz, 8H,
), 4.00 (t, J¼6.8 Hz, 4H, OCH
OCH
), 6.85 (s, 4H, ArH), 7.50 (d, J¼16.6 Hz, 2H, olefinic H), 7.66 (s,
H, ArH), 7.91 (d, J¼16.6 Hz, 2H, olefinic H); C NMR (CDCl
ꢁ2), 22.68, 22.70, 26.13 (ꢁ2), 29.31, 29.39 (ꢁ2), 29.46, 29.56, 30.35,
1.84, 31.90, 69.22, 73.57, 105.57, 123.47, 126.82, 129.19, 132.67,
33.44, 138.80, 153.35, 153.93; FAB-MS (positive, NBA) m/z 1109
3
)
d
0.89 (t, J¼6.8 Hz, 18H, CH
3
),
ported previously.13
1
(
2
2
CH CH ), 1.77
2
2
2
2
4
.2. Spectroscopic measurement
2
2
2
2
13
UVevis spectra were measured in a 1.0 cm width quartz cell at
2
(
3
1
3
) d 14.11
ꢂ5
1
.0ꢁ10 M. Fluorescence spectra were measured in a 1.0 cm width
ꢂ6
quartz cell at 1.0ꢁ10 M. Absolute fluorescence quantum yield was
determined by Hamamatsu Photonics C9920-01 Absolute PL
Quantum Yield Measurement System.
þ
112 2 6
(M ). Anal. Calcd for C70H N O S (1109.71): C, 75.76; H, 10.17; N,
2.52. Found: C, 75.58; H, 10.09; N, 2.71.
4
.3. Preparation of spin-coating films
4.6. 4,7-Bis{2-[3,4,5-tris(2-ethylhexyloxy)phenyl]ethenyl}-
Film sample for the measurements of UVevis and fluorescence
2,1,3-benzothiadiazole (3c)
spectroscopy was prepared by drop casting and the subsequent
ꢂ3
spin-coating (2000 rpm, 30 s) from a 1.0ꢁ10 M hexane solution
To a suspension of 1 (88 mg, 0.3 mmol), 2c (310 mg, 0.63 mmol),
and triethylamine (0.41 mL, 3 mmol) in dry DMF (3 mL) was added
(
100
m
Lꢁ3) on quartz cell (12.5ꢁ12.5ꢁ45 mm). Film sample for the

T. Ishi-i et al. / Tetrahedron 69 (2013) 9475e9480
9479
a solution of palladium acetate (6.6 mg, 0.03 mmol) and tri(o-tolyl)
phosphine (18.3 mg, 0.6 mmol) in dry DMF (1.5 mL) at 100 C under
40.55, 65.80 (CH
FAB-MS (positive, NBA) m/z 492 (M ). Anal. Calcd for C31
2
OH), 71.05, 75.91, 104.52, 135.91, 137.21, 153.50;
ꢀ
þ
H
56
O
4
an argon atmosphere, and the mixture was allowed to stand for
(492.77): C, 75.56; H, 11.45. Found: C, 75.73; H, 11.49.
ꢀ
15 h. After the reaction mixture was cooled to 0 C, it was quenched
with aqueous 1.2 N hydrochloric acid solution and extracted with
dichloromethane. The organic layer was washed with brine suffi-
ciently, dried over anhydrous magnesium sulfate, and evaporated
in vacuo to dryness. The residue was purified by silica gel column
chromatography (WAKO C300) eluting with chloroform and by GPC
4.9. 1,2,3-Tris(2-ehtylhexyloxy)-5-formylbenzene (7c)
To a solution of 6c (2.11 g, 4.26 mmol) in dry 1,4-dioxane (26 mL)
ꢀ
was added DDQ (1.02 g, 4.5 mmol) at 0 C under an argon atmo-
sphere, and stirred at room temperature for 2 h. The reaction
mixture was evaporated in vacuo to dryness. The residue was
suspended in dichloromethane (10 mL), then the insoluble hydro-
quinone was removed by filtration and washed with dichloro-
methane. The combined filtrates were evaporated in vacuo to
dryness. The residue was purified by silica gel column chroma-
tography (KANTO 60N) eluting with hexane/dichloromethane (7:3,
eluting with chloroform to give 3c in 61% yield (258 mg,
ꢂ1
0
2
.184 mmol): dark red viscous liquid; IR (NaCl, cm ) 3035, 2957,
927, 2872, 1577, 1503, 1463, 1431, 1380, 1325, 1281, 1238, 1119,
1
1010, 960, 835; H NMR (CDCl
3
)
d
0.92 (t, J¼7.3 Hz, 18H, CH
), 1.23e1.40 (m, 24H, CH ), 1.40e1.62 (m, 24H,
), 1.64e1.86 (m, 6H, CH), 3.83e3.99 (m, 12H, CH ), 6.84 (s, 4H,
3
), 0.96
(
CH
t, J¼7.3 Hz, 18H, CH
3
2
2
2
ArH), 7.51 (d, J¼16.6 Hz, 2H, olefinic H), 7.68 (s, 2H, ArH), 7.93 (d,
v/v) to give 7c in 96% (2.01 g, 4.10 mmol) as pale yellow oil: IR (NaCl,
13
ꢂ1
J¼16.6 Hz, 2H, olefinic H); C NMR (CDCl
3
)
d
11.18, 11.23, 14.16,
cm ) 3086, 2958, 2928, 2873, 2860, 1696 (
n
C
]
O
), 1584, 1496, 1462,
0.90 (t,
), 1.25e1.38 (m, 12H,
2
), 1.63e1.82 (m, 3H, CH), 3.87e3.99 (m,
1
1
4
4.19, 23.13, 23.18, 23.71, 23.86, 29.17, 29.34, 30.51, 30.56, 39.68,
1439, 1382, 1329, 1228, 1139, 1117; H NMR (CDCl
J¼7.3 Hz, 9H, CH ), 0.92 (t, J¼7.3 Hz, 9H, CH
CH ), 1.38e1.60 (m, 12H, CH
6H, OCH ), 7.26 (s, 2H, ArH), 9.84 (s, 1H, CHO); C NMR (CDCl
11.11, 11.18, 14.13, 14.17, 23.08, 23.13, 23.60, 23.78, 29.07, 29.27,
3
) d
0.61, 71.16, 76.05, 104.75, 123.36, 126.88, 129.22, 132.57, 133.61,
3
3
þ
138.52, 153.58, 153.96; FAB-MS (positive, NBA) m/z 1109 (M ). HR-
2
þ
13
FABMS (positive, NBA) m/z 1108.8246 (M , calcd for C70
H
112
N
2
O
6
S
2
3
)
1108.8241).
d
3
0.38, 30.48, 39.50, 40.61, 71.27, 76.00,107.28,131.29,143.71,153.67,
þ
4
.7. Methyl 3,4,5-tris(2-ethylhexyl)benzoate (5c)
191.48 (C]O); FAB-MS (positive, NBA) m/z 490 (M ). Anal. Calcd for
31 54 4
C H O (490.76): C, 75.87; H, 11.09. Found: C, 75.69; H, 11.02.
To a solution of 1-bromo-2-ethylhexane (11.4 mL, 66 mmol) and
(3.68 g, 20.0 mmol) in dry DMF (100 mL) was added potassium
4
4.10. 1,2,3-Tris(2-ehtylhexyloxy)-5-ethenylbenzene (2c)
carbonate (24.8 g, 180 mmol) under an argon atmosphere, and
ꢀ
heated at 70 C for 27 h. The reaction mixture was quenched by
To a suspension of methyltriphenylphosphonium bromide
(1.78 g, 5 mmol) in dry THF (25 mL) was added dropwise 1.57 M
addition of water and neutralized with cold aqueous 1 N hydro-
chloric acid solution. The mixture was extracted with dichloro-
methane, washed with water sufficiently, dried over anhydrous
magnesium sulfate, and evaporated in vacuo to dryness. The resi-
due was purified by silica gel column chromatography (WAKO
ꢀ
butyllithium hexane solution (3.03 mL, 5 mmol) at ꢂ78 C for
10 min under an argon atmosphere and allowed to stand for
30 min. The white suspension was changed to yellow suspension.
Then, 7c (1.96 g, 10 mmol) in dry THF (2.5 mL) was added dropwise
ꢀ
C300) eluting with hexane/dichloromethane (2:1, v/v) to give 5c in
8% (8.16 g, 15.67 mmol) as pale yellow oil: IR (NaCl, cm ) 3100,
for 5 min at ꢂ78 C. The mixture was warmed up to room tem-
ꢂ1
7
2
1
perature and allowed to stand for 3 h. The reaction mixture was
poured into water and extracted with ethyl acetate. The organic
layer was washed with water, dried over anhydrous magnesium
sulfate, and evaporated in vacuo to dryness. The residue was pu-
rified by silica gel column chromatography (WAKO C300) eluting
with hexane/dichloromethane (9:1, v/v) to give 2c in 40% (494 mg,
958, 2928, 2873, 2860, 2731, 1722 (
n
]
C O
), 1588, 1460, 1432, 1334,
0.90 (t, J¼7.3 Hz, 9H, CH ), 0.93
), 1.27e1.36 (m, 12H, CH ), 1.40e1.60 (m, 12H,
), 1.65e1.80 (m, 3H, CH), 3.85e3.95 (m, 6H, OCH ), 3.90 (s, 3H,
11.12, 11.20, 14.13,
4.17, 23.09, 23.14, 23.64, 23.81, 29.10, 29.29, 30.43, 30.50, 39.55,
1
217; 1108, 766; H NMR (CDCl
3
)
d
3
(
t, J¼7.3 Hz, 9H, CH
3
2
CH
2
2
13
3
COOMe), 7.25 (s, 2H, ArH); C NMR (CDCl ) d
ꢂ1
1
1.01 mmol): colorless oil; IR (NaCl, cm ) 3087, 2927, 2872, 2860,
4
0.60, 52.14 (COOCH
3
), 71.16, 75.88, 107.29, 124.50, 142.15, 153.0,
1578, 1503, 1463, 1434, 1416, 1380, 1326, 1235, 1118, 1012, 985, 899,
þ
1
167.07 (C]O); FAB-MS (positive, NBA) m/z 520 (M ). Anal. Calcd for
833; H NMR (CDCl
3
)
d
0.90 (t, J¼6.8 Hz, 9H, CH
), 1.25e1.37 (m, 12H, CH ), 1.39e1.60 (m, 12H, CH
.66e1.78 (m, 3H, CH), 3.79e3.89 (m, 6H, OCH
), 5.17 (d, J¼10.7 Hz,
1H, olefinic H), 5.63 (d, J¼17.6 Hz, 1H, olefinic H), 6.60 (s, 2H, ArH),
3
), 0.93 (t, J¼7.6 Hz,
C
H
32 56
O
5
(520.78): C, 73.80; H, 10.84. Found: C, 73.92; H, 10.71.
9H, CH
3
2
2
),
1
2
4
.8. 1,2,3-Tris(2-ehtylhexyloxy)-5-hydroxymethylbenzene (6c)
13
6
.61 (dd, J¼10.7, 17.6 Hz, 1H, olefinic H); C NMR (CDCl
3
) d 11.13,
To a suspension of lithium aluminum hydride (380 mg,
11.21,14.12,14.18, 23.12, 23.18, 23.69, 23.81, 29.13, 29.33, 30.52 (ꢁ2),
10 mmol) in dry ether (10 mL) was added dropwise 5c (2.60 g,
39.61, 40.57, 71.08, 75.99, 104.05, 112.61, 132.67, 137.05, 138.03,
ꢀ
þ
5
.0 mmol) in dry ether (10 mL) at 0 C under an argon atmosphere,
153.39; FAB-MS (positive, NBA) m/z 488 (M ). Anal. Calcd for
and stirred at room temperature for 1 h. The reaction mixture was
quenched by addition of ethyl acetate. The resulting mixture was
poured into cold water carefully, and neutralized with cold aqueous
32 56 3
C H O (488.79): C, 78.63; H, 11.55. Found: C, 78.48; H, 11.38.
Acknowledgements
1
N sulfuric acid solution. The mixture was extracted with
dichloromethane, washed with brine and water, dried over anhy-
drous magnesium sulfate, and evaporated in vacuo to dryness. The
residue was purified by silica gel column chromatography (WAKO
We thank Professor Dr. Katsuhiko Fujita (Kyushu University,
Japan), Professor Dr. Hiroyuki Nakamura, and Professor Dr. Masumi
Miyazaki (AIST, Japan) for the measurements of the absolute fluo-
rescence quantum yield.
C300) eluting with hexane/dichloromethane (1:2, v/v) to give 6c in
ꢂ1
9
8% (2.41 g, 4.88 mmol) as colorless oil: IR (NaCl, cm ) 3366 (
n
OH),
3
054, 2958, 2927, 2872, 1591, 1505, 1436, 1381, 1331, 1231, 1121,
Supplementary data
1
1015; H NMR (CDCl
3
)
d
0.90 (t, J¼7.6 Hz, 9H, CH
3
), 0.93 (t, J¼7.3 Hz,
),
), 4.59 (d, J¼5.9 Hz,
11.11, 11.21, 14.14,
9
H, CH
3
), 1.26e1.36 (m, 13H, CH and OH), 1.37e1.60 (m, 12H, CH
2
2
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tet.2013.08.066.
These data include MOL files and InChiKeys of the most important
compounds described in this article.
1.63e1.80 (m, 3H, CH), 3.77e3.88 (m, 6H, OCH
2
13
2
H, ArCH
2
), 6.55 (s, 2H, ArH); C NMR (CDCl
3
)
d
14.19, 23.11, 23.18, 23.69, 23.77, 29.09, 29.32, 30.47 (ꢁ2), 39.56,

9480
T. Ishi-i et al. / Tetrahedron 69 (2013) 9475e9480
References and notes
N.; Mine, T.; Imamura, S.; Shigeiwa, M.; Gorohmaru, H.; Maeda, S. Chem. Lett.
009, 38, 1042e1043.
. (a) van Mullekom, H. A. M.; Vekemans, J. A. J. M.; Meijer, E. W. Chem.dEur. J.
998, 4, 1235e1243; (b) Kono, T.; Kumaki, D.; Nishida, J.-I.; Tokito, S.; Yama-
shita, Y. Chem. Commun. 2010, 3265e3267; (c) Dou, C.; Chen, D.; Iqbal, J.; Yuan,
Y.; Zhang, H.; Wang, Y. Langmuir 2011, 27, 6323e6329; (d) Moro, A. V.; Ferreira,
P. C.; Migowski, P.; Rodembusch, F. S.; Dupont, J. Tetrahedron 2013, 69, 201e206;
2
9
1
. (a) Mitschke, U.; B a€ uerle, P. J. Mater. Chem. 2000, 10, 1471e1507; (b) Shimizu,
1
M.; Hiyama, T. Chem.dAsian J. 2010, 5, 1516e1531.
2. (a) Sapsford, K. E.; Berti, L.; Medintz, I. L. Angew. Chem., Int. Ed. 2006, 45,
4
562e4588; (b) Liu, J.; Cao, Z.; Lu, Y. Chem. Rev. 2009, 109, 1948e1998; (c)
Kobayashi, H.; Ogawa, M.; Alford, R.; Choyke, P. L.; Urano, Y. Chem. Rev. 2010,
10, 2620e2640.
(
e) Ruan, Y.-B.; Yu, Y.; Li, C.; Bogliotti, N.; Tang, J.; Xie, J. Tetrahedron 2013, 69,
603e4608.
0. Kato, S.; Matsumoto, T.; Shigeiwa, M.; Gorohmaru, H.; Maeda, S.; Ishi-i, T.;
Mataka, S. Chem.dEur. J. 2006, 12, 2303e2317.
1. Ishi-i, T.; Ikeda, K.; Kichise, Y.; Ogawa, M. Chem.dAsian J. 2012, 7, 1553e1557.
2. Meier, H. Angew. Chem., Int. Ed. 2005, 44, 2482e2506.
1
4
3. Valeur, B.; Berberan-Santos, M. N. Molecular Fluorescence: Principle and Appli-
cations, 2nd ed.; Wiley-VCH: Weinheim, 2012, Chapter 4.
1
4
. (a) Loudet, A.; Burgess, K. Chem. Rev. 2007, 107, 4891e4932; (b) Ulrich, G.;
Ziessel, R.; Harriman, A. Angew. Chem., Int. Ed. 2008, 47, 1184e1201; (c) Ume-
zawa, K.; Nakamura, Y.; Makino, H.; Citterio, D.; Suzuki, K. J. Am. Chem. Soc.
1
1
1
3. (a) Becker, H. D.; Bjork, A.; Adler, E. J. Org. Chem. 1980, 45, 1596e1600; (b) Si-
moni, D.; Grisolia, G.; Giannini, G.; Roberti, M.; Rondanin, R.; Piccagli, L.; Bar-
uchello, R.; Rossi, M.; Romagnoli, R.; Invidiata, F. P.; Grimaudo, S.; Jung, M. K.;
Hamel, E.; Gebbia, N.; Crosta, L.; Abbadessa, V.; Cristina, A. D.; Dusonchet, L.;
Meli, M.; Tolomeo, M. J. Med. Chem. 2005, 48, 723e736; (c) Gehringer, L.;
Guillon, D.; Donnio, B. Macromolecules 2003, 36, 5593e5601; (d) Maruyama, S.;
Sato, K.; Iwahashi, H. Chem. Lett. 2010, 39, 714e716.
4. (a) Reichardt, C. Chem. Rev. 1994, 94, 2319e2358; (b) Kubo, K.; Momotake, A.;
Kanna, Y.; Nishimura, Y.; Arai, T. Chem. Commun. 2011, 3867e3869.
5. (a) Xu, D.; Adachi, C. Appl. Phys. Lett. 2009, 95, 053304-1e053304-3; (b) Kubota, K.;
Hirata, S.;Shibano,Y.;Hirata,O.;Yahiro,M.;Adachi, C.Chem. Lett. 2012, 41, 934e936;
2008, 130, 1550e1551; (d) Okujima, T.; Tomimori, Y.; Nakamura, J.; Yamada, H.;
Uno, H.; Ono, N. Tetrahedron 2010, 66, 6895e6900.
5
. (a) W u€ rthner, F. Chem. Commun. 2004, 1564e1579; (b) Nakazono, S.; Imazaki,
Y.; Yoo, H.; Yang, J.; Sasamori, T.; Tokitoh, N.; C eꢀ dric, T.; Kageyama, H.; Kim, D.;
Shinokubo, H.; Osuka, A. Chem.dEur. J. 2009, 15, 7530e7533.
. Chen, C. T. Chem. Mater. 2004, 16, 4389e4400.
6
7. (a) Raimundo, J.-M.; Blanchard, P.; Brisset, H.; Akoudad, S.; Roncali, J. Chem.
1
Commun. 2000, 939e940; (b) Huang, J.; Qiao, X.; Xia, Y.; Zhu, X.; Ma, D.; Cao, Y.;
Roncali, J. Adv. Mater. 2008, 20, 4172e4175; (c) Zhou, Y.; He, Q.; Yang, Y.; Zhong,
H.; He, C.; Sang, G.; Liu, W.; Yang, C.; Bai, F.; Li, Y. Adv. Funct. Mater. 2009, 19,
1
2978e2986.
(
c) Babu, S. S.; Aimi, J.; Ozawa, H.; Shirahata, N.; Saeki, A.; Seki, S.; Ajayaghosh, A.;
M o€ hwald, H.; Nakanishi, T. Angew. Chem., Int. Ed. 2012, 51, 3391e3395.
6. Ishi-i, T.; Murakami, K.; Imai, Y.; Mataka, S. J. Org. Chem. 2006, 71, 5752e5760.
8
. (a) Zhang, X.; Gorohmaru, H.; Kadowaki, M.; Kobayashi, T.; Ishi-i, T.; Thiemann,
T.; Mataka, S. J. Mater. Chem. 2004, 14, 1901e1904; (b) Ishi-i, T.; Nakamura, N.;
Esaki, N.; Amemori, S. Chem. Lett. 2008, 37, 1166e1167; (c) Ishi-i, T.; Nakamura,
1