New photochromic diarylethenes bearing a condensed aromatics moiety

Article abstract of DOI:10.1016/j.tetlet.2011.04.063

A new class of diarylethenes based on a hybrid structure of naphthalene and thiophene have been developed and their properties including photochromism, fatigue resistance, and fluorescence have been investigated. The condensed aromatic naphthalene was con

Full text of DOI:10.1016/j.tetlet.2011.04.063

Tetrahedron Letters 52 (2011) 3306–3310
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
New photochromic diarylethenes bearing a condensed aromatics moiety
⇑
Renjie Wang, Shouzhi Pu , Gang Liu, Weijun Liu, Hongying Xia
Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, Nanchang 330013, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 15 February 2011
Revised 4 April 2011
Accepted 15 April 2011
Available online 23 April 2011
A new class of diarylethenes based on a hybrid structure of naphthalene and thiophene have been devel-
oped and their properties including photochromism, fatigue resistance, and fluorescence have been
investigated. The condensed aromatic naphthalene was connected directly to the central cyclopentene
ring as an aryl moiety and available to participate in the photoinduced cyclization reaction. All of these
compounds have exhibited good photochromism, notable fatigue resistance, and obvious fluorescence
photo-switches in both solution and polymer matrix. Nevertheless, significantly different properties have
been observed among these diarylethenes, which may be attributed to the effect of different substituent
groups. Compared with the analogs bearing other six-membered aryl unit, the naphthalene moiety is
more conducive, which leads to higher molar absorption coefficient and blue shift of the absorption
maximum.
Keywords:
Diarylethene
Photochromism
Naphthalene moiety
Optical characteristic
Ó 2011 Elsevier Ltd. All rights reserved.
Organic photochromic materials have attracted much attention
due to their potential application in erasable optical memory,
photo physical switch components, and display devices.1 In the
past several decades, many new diarylethene systems with differ-
ent heteroaryl moieties were explored. Among them, most of the
central ethene containing bridging units were 3-thienyl,2
3-benzothienyl,3 and 2-thienyl4 groups. While others involved
heteroaryl moieties, such as 3-pyrolyl,5 4-thiazolyl,6 4-oxazolyl,7
4-pyrazolyl,8 3-indolyl,9 and so on. Generally, the aryl moieties of
diarylethene can strongly influence their photochromic character-
istics. For instance, the diarylethenes having indole rings exhibit
excellent fluorescent photoswitches,9 and diarylethenes bearing
thiophene/benzothiophene moieties show excellent thermal sta-
bility and outstanding fatigue resistance.10 Nakagawa et al. devel-
oped triangular terthiophene derivatives which showed relatively
high fluorescence quantum yield.11 Yamaguchi et al. developed a
withdrawing groups can shift the absorption maxima to longer
wavelengths and decrease the cyclization quantum yield.13 Previ-
ously, we have reported that diarylethenes bearing different sub-
stituents can exhibit distinguishable features that resulted from
the substituent effects.14
The hexatriene backbone of photochromic diarylethene systems
is mainly confined to the five-membered heteroaryl rings. In the
case of six-membered rings as aryl moieties, only a few symmetri-
cal diarylethenes having two phenyl/naphthyl rings have been re-
ported, and most of these derivatives are thermally reversible with
poor photochromism.15 We have reported a new class of diaryleth-
ene derivatives bearing both five-membered and six-membered
moieties, which have shown new characteristics as compared to
the diarylethenes containing only five-membered heteroaryl
rings.16 The condensed aromatics naphthalene is a unique aryl unit
because of its strong aromatic stabilization energy. To the best of
our knowledge, there has been only one example of a symmetrical
photochromic diarylethene bearing two naphthyl rings, as re-
ported by Uchida et al.15b The diarylethene bearing naphthyl rings
possesses excellent thermal stability, where the absorption inten-
sity of its closed-ring isomer remains relatively constant for more
than 500 h even at 343 K.15b However, photochromic diarylethene
derivatives based on a hybrid structure of condensed aromatics
and five-membered heteroaryl moieties have not hitherto been
reported.
new kind of 6
p
conjugated photochromic system with a bis(2,30-
benzothienyl) unit, which exhibited efficient photochromism and
thermal stability for the colored isomers.12 However, diarylethenes
bearing pyrrole rings are thermally unstable even at rt in the dar-
k.5a Apart from the fact that the aryl moieties have critical effects
on the photochromic characteristics of diarylethene derivatives,
the functional substituent can also notably affect photochromic
properties, such as the absorption maxima, the absorption coeffi-
cients, and the quantum yields. Representatively, the electron-
donating substituents of bis(3-thienyl)ethene diarylethenes can
decrease the cycloreversion quantum yields and increase the
absorption coefficients of the closed-ring isomers, while electron-
In this Letter, we have investigated a new class of asymmet-
rical photochromic diarylethene derivatives bearing both naph-
thalene and thiophene moieties. The synthesized diarylethenes
are 1-(2-methylnaphthyl)-2-(methyl-5-phenyl-3-thienyl)perflu-
orocyclopentene (1o), 1-(2-methylnaphthyl)-2-[2-methyl-5-(3-
methoxyphenyl)-3-thienyl]perfluorocyclopentene (2o), and 1-(2-
⇑
Corresponding author. Tel./fax: +86 791 3831996.
E-mail address: pushouzhi@tsinghua.org.cn (S. Pu).
0040-4039/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2011.04.063

R. Wang et al. / Tetrahedron Letters 52 (2011) 3306–3310
3307
methylnaphthyl)-2-[2-methyl-5-(3-trifluoromethylphenyl)-3-thi-
0.6
0.4
0.2
0.0
Vis
enyl]perfluorocyclopentene (3o). All of these diarylethene deriv-
atives showed good photochromism in both solution and poly
(methyl methacrylate) (PMMA) amorphous films. The photochro-
mic scheme of 1o–3o is shown in Scheme 1.
A
UV
The synthetic route for diarylethenes 1o–3o is shown in
Scheme 2. First, the phenylthiophene derivatives (5a–c) were pre-
pared by Suzuki coupling of the three bromobenzene derivatives
with a thiophene boronic acid.17 Then, 2-methyl-1-bromonaphtha-
lene (6) was lithated and coupled with octafluorocyclopentene to
give 2-methyl-1-naphthyl-perfluorocyclopentene (7). Finally, com-
pounds 5a–c were separately lithiated and then coupled with com-
pound 7 to give diarylethenes 1o–3o, respectively. The structures
of diarylethenes 1o–3o were confirmed by elemental analysis,
NMR, and IR.18
UV
Vis
300
400
500
600
Wavelength(nm)
The photochromic behaviors of diarylethenes 1–3 induced by
photoirradiation at rt were measured both in hexane
(2.0 ꢀ 10ꢁ5 mol Lꢁ1) and in PMMA films (10%, w/w). In hexane,
the absorption spectral change of diarylethene 1 and the color
changes of diarylethenes 1–3 are shown in Figure 1. The open-ring
B
isomer 1o exhibited a sharp absorption peak at 261 nm (e,
2.76 ꢀ 104 L molꢁ1 cmꢁ1) in hexane, which arose from
p?
p⁄ tran-
sition.19 Upon irradiation with UV light, the colorless solution of 1o
turned red and a new visible absorption band was observed at
508 nm (
e
, 1.5 ꢀ 104 L molꢁ1 cmꢁ1), while the intensity of the ori-
Figure 1. Absorption spectral changes of diarylethene 1 (A) and the color changes
of diarylethenes 1–3 (B) by photoirradiation in hexane (2.0 ꢀ 10ꢁ5 mol Lꢁ1) at rt.
ginal peak at 261 nm decreased indicating the formation of the
closed-ring isomer 1c. After irradiation with a visible light (k
>500 nm), the red color was bleached to colorless by virtue of
the reproduction of the original open-ring isomer 1o. At the photo-
stationary state, the isosbestic point of diarylethene 1 was ob-
served at 289 nm, which supported the reversible two
component photochromic reaction schemes.20 Likewise, the spec-
tra of diarylethenes 2 and 3 demonstrated similar photochromism
trend in hexane. Their color changes upon photoirradiation are
shown in Figure 1(B). In the photostationary state, the isosbestic
points of diarylethenes 2 and 3 were observed at 290 and
277 nm, respectively. In addition, the photoconversion ratios of
the three diarylethenes were analyzed by HPLC in the photosta-
tionary state, with the value of 63% for 1, 78% for 2, and 64% for
3, respectively (Table 1). In PMMA films, diarylethenes 1–3 also
showed similar photochromic property, but the absorption
F
F
F
F
F
F
F
F
F
F
F
F
UV
Vis
S
S
1c: R =
2c: R =
3c: R =
H
OCH3
CF3
1o: R =
2o: R =
3o: R =
H
OCH3
CF3
R
R
Scheme 1. Photochromism of diarylethenes 1o–3o.
R
Br
Br
Br
Pd(PPh3)4, NaCO3,aq
S
B(OH)2
S
4
5a: R =
5b: R =
5c: R =
H
OCH3
CF3
5
R
F
F
Br
F
F
1) n-BuLi,-78 O
C
F
F
2) C5F8
F
6
F
F
7
F
F
F
F
n-BuLi
-78OC
S
1o: R =
2o: R =
3o: R =
H
OCH3
CF3
R
Scheme 2. Synthetic route for diarylethenes 1o–3o.

3308
R. Wang et al. / Tetrahedron Letters 52 (2011) 3306–3310
Table 1
Absorption spectral properties of diarylethenes 1–3 in hexane (2.0 ꢀ 10ꢁ5 mol Lꢁ1) and in PMMA films (10%, w/w) at rt
Compd
ko,max/nma
(e
/L molꢁ1 cmꢁ1
)
kc,max/nmb
(
e
/L molꢁ1 cmꢁ1
)
Uc
PRd (%)
Hexane
PMMA
Hexane
PMMA
Uo–c
Uc–o
1
2
3
261 (2.76 ꢀ 104)
264 (3.22 ꢀ 104)
263 (2.46 ꢀ 104)
264
265
266
508 (1.5 ꢀ 104)
514 (2.1 ꢀ 104)
510 (1.3 ꢀ 104)
524
528
528
0.31
0.55
0.32
0.21
0.13
0.29
63
78
64
a
b
c
The maximum absorption peak of the open-ring isomers.
The maximum absorption peak of the closed-ring isomers.
Quantum yields of cyclization (Uo–c) and cycloreversion (Uc–o), respectively.
Photoconversion ratios of diarylethenes 1–3 (PR%) in the photostationary state.
d
1.0
1.0
A
0.8
0.6
0.4
0.2
0.0
B
0.8
0.6
1o
0.4
0.2
0.0
2o
3o
1o
2o
3o
0
50
100
150
200
0
20
40
60
80
100
Repeat cycles
Repeat cycles
Figure 2. Fatigue resistance of diarylethenes 1–3 in hexane (A) and in PMMA films (B) in air atmosphere at rt. Initial absorbance of the sample was fixed to 1.0.
maxima of the closed-ring isomers of diarylethenes 1–3 in PMMA
films are at longer wavelengths than those in hexane.13b,16,21 The
red shift values of the absorption maxima of the closed-ring iso-
mers are 16 nm for 1c, 14 nm for 2c, and 18 nm for 3c, respectively.
The red shift phenomenon may be attributed to the polar effect of
the polymer matrix in solid medium.22
quite different from those reported on diarylethenes bearing a phe-
nyl moiety, in which the cyclization quantum yield significantly in-
creased with the increase of electron-withdrawing ability, and the
cycloreversion quantum yield showed the reverse trend.16a Fur-
thermore, the naphthalene moiety has also a significant effect on
the photochromic features of diarylethenes 1–3. When replacing
the naphthalene moiety with a pyridine unit in the same molecular
skeleton of diarylethene, the absorption maximum markedly
shifted to a longer wavelength and the cycloreversion quantum
yield notably decreased.16c
The thermal stabilities of open-ring and closed-ring isomers of
diarylethenes 1–3 were tested in ethanol both at rt and at 351 K.
We stored these solutions in ethanol at rt in the dark and then ex-
posed them to air for more than 10 days, and no changes have been
observed in the UV/Vis spectra of diarylethenes 1–3. At 351 K,
diarylethenes 1–3 still showed excellent thermal stabilities for
more than 8 h.
The photochromic features of diarylethenes 1–3 are summa-
rized in Table 1. The absorption maximum of the unsubstituted
parent diarylethene 1 was at the shortest wavelength both in
hexane and in a PMMA film. Replacing the hydrogen atom at the
meta-position of the terminal benzene ring with either an elec-
tron-donating substituent (methoxy, such as in compound 2) or
with an electron-withdrawing substituents (trifluoromethyl, such
as in compound 3) resulted in a minor red shift. When substituting
with the electron-donating methoxy group in the same diaryleth-
ene system, the molar absorption coefficients of the two isomers
increased notably, compared with the unsubstituted parent
diarylethene 1. However, the replacement with the strong
electron-withdrawing trifluoromethyl group decreased signifi-
cantly the molar absorption coefficients of the two isomers of
diarylethene 3. The result is consistent with that of diarylethenes
bearing a pyrrole unit.23
Fatigue resistance is a critical factor for the practical applications
in optical devices.10a,24 The fatigue resistances of diarylethenes 1–3
4500
The quantum yields of unsubstituted parent diarylethene 1
were 0.31 for the cyclization reaction and 0.21 for the cyclorever-
sion reaction. The quantum yield in cyclization increased signifi-
cantly when the electron-donating group was substituted at the
meta-position of the terminal benzene ring, and the quantum yield
in cycloreversion improved notably when the electron-withdraw-
ing group was substituted at the same position, compared with
the parent diarylethene 1. Therefore, diarylethene 2 has the high-
est cyclization quantum yield and the lowest cycloreversion quan-
tum yield, and diarylethene 3 has the highest cycloreversion
quantum yield among the three-diarylethene derivatives. The re-
sult indicated that the electron-donating substituent could notably
enhance the cyclization quantum yield and suppress the cyclore-
version quantum yield, but the electron-withdrawing substituents
could increase the cycloreversion quantum yield. Our findings are
3600
2700
3o
2o
1o
1800
900
0
350
400
450
500
550
Wavelength (nm)
Figure 3. Emission spectra of diarylethenes 1–3 in hexane (2.0 ꢀ 10ꢁ5 mol Lꢁ1) at rt
when excited at 298 nm.

R. Wang et al. / Tetrahedron Letters 52 (2011) 3306–3310
3309
3000
A
B
1500
1200
900
600
300
0
2400
Vis
Vis
UV
1800
1200
600
0
UV
350
400
450
500
550
350
400
450
500
550
Wavelength(nm)
Wavelength(nm)
Figure 4. Emission intensity changes of diarylethenes 1 both in hexane (2.0 ꢀ 10ꢁ5 mol Lꢁ1) and in PMMA film (10%, w/w) by photoirradiation at rt: (A) in hexane
(kex = 298 nm), (B) in PMMA films (kex = 300 nm).
were examined both in hexane and in PMMA films by alternating
irradiating with UV and visible light in air at rt, as shown in Figure 2.
In hexane, the coloration and decoloration cycles of diarylethenes 1–
3 can be repeated at least 100 times with 14% degradation of 1c, 12%
of2c, and8%of 3c, respectively, whichmayresultfromtheformation
of an epoxide.25 In PMMA films, diarylethenes 1–3 exhibited excel-
lent photochromism after 200 cycles with only 28% degradation of
1c, 21% degradation of 2c, and 8% of 3c, respectively. Overall, the
fatigue resistance of diarylethene bearing an electron-withdrawing
group was much better than that of diarylethene bearing an elec-
tron-donating group both in hexane and in PMMA films. The result
is in good agreement with that reported for diarylethenes bearing
both thiophene and benzene moieties,16a but is completely contrary
to that reported for analogs bearing a pyridine moiety.16c
state, in which its emission intensity was quenched to ca. 43% in
hexane and 47% in PMMA film, respectively. As with diarylethene
1, the diarylethenes 2 and 3 also functioned as a notable fluores-
cent switch upon photoirradiation both in hexane and in PMMA
films. In the photostationary state, their emission intensities were
quenched ca. 24% for 2 and 32% for 3 in solution and ca. 39% for 2
and 34% for 3 in PMMA films. The result showed that the fluores-
cent modulation efficiencies of diarylethenes 1–3 in hexane were
higher than those in PMMA film. This result is in stark contrast
to the diarylethenes bearing both thiophene and benzene moieties,
where the fluorescent modulation efficiencies in hexane were
much lower than those in PMMA film.16a The excellent fluorescent
modulation efficiency found in diarylethenes 2 and 3 could find
promising application in photoswitchable devices, such as optical
memory and fluorescent modulation switches.27a,28
The fluorescence spectra of diarylethenes 1o–3o both in hexane
(2.0 ꢀ 10ꢁ5 mol Lꢁ1) and in PMMA films (10%, w/w) were mea-
sured at rt. In hexane, the emission peaks of 1o–3o were observed
at 420, 415, and 424 nm when excited at 298 nm (Fig. 3), and 428,
425, and 421 nm in PMMA films when excited at 300 nm. Com-
pared to those in hexane, the emission peaks of diarylethenes 1o
and 2o show a bathochromic shift in PMMA films, which is well
consistent with those of their maxima absorption wavelengths.
However, the emission peak of 3o shows a minor hypsochromic
shift in PMMA film. Among the three compounds, the emission
intensity of 3o is the strongest and that of 1o is the smallest both
in hexane solution and in PMMA films. The result suggested that
different substituents attached at the meta-position of the benzene
ring had a significant effect not only on the emission peak but also
on the emission intensity. The fluorescence quantum yields of
diarylethenes 1o–3o were determined to be 0.011, 0.012, and
0.018, respectively, and anthracene was used as reference. The re-
sults demonstrated that the electron-withdrawing substituent
could effectively enhance the fluorescence quantum yield of diary-
lethene bearing a naphthalene unit. This observation is opposite to
those of the diarylethenes bearing a biphenyl unit whose fluores-
cence quantum yields increased with the electron-donating
ability.26
In conclusion, three new photochromic diarylethenes based on a
condensed aromatic naphthalene skeleton have been explored for
the first time and their properties have been investigated. This
new photochromic system showed good photochromism, strong
fatigue resistance, and obvious fluorescent switch behavior both
in hexane solution and in PMMA films. Our results indicate that
the substituents at the meta-position of the terminal benzene ring
had a significant effect on the properties of these diarylethene
derivatives. In addition, the condensed aromatics aryl moiety
induced dramatic properties differing from other diarylethenes
with five and six-membered aryl moieties reported so far. The
present work provides a useful design strategy in tuning the photo-
chromic properties of diarylethenes and seeking for their potential
applications.
Acknowledgments
This work was supported by Program for the NSFC of China
(20962008), New Century Excellent Talents in University (NCET-
08-0702), the Project of Jiangxi Academic and Technological Leader
(2009DD00100), National Natural Science Foundation of Jiangxi
Province (2009GZH0034) and the Science Funds of the Education
Office of Jiangxi, China (GJJ09646, GJJ09567).
Just like most of the diarylethenes,27 the fluorescence of closed-
ring isomers of diarylethenes is inactive. When the pohoisomeriza-
tion reaction of diarylethens 1–3 occurs, the notable fluorescent
switches were observed both in hexane and in PMMA films. Upon
irradiation with UV light, the photocylization reaction induced the
closed-ring isomers and the emission intensity of diarylethenes 1–
3 decreased gradually. The reverse irradiation by appropriate
wavelength visible light regenerated their open-ring isomers and
the original emission intensity. During the process of photoisomer-
ization, diarylethene 1 exhibited changes in its fluorescence both
in hexane and in a PMMA film as shown in Figure 4. Upon
irradiation with UV light, the sample reached the photostationary
References and notes
1. (a) Irie, M.; Kobatake, S.; Horichi, M. Science 2001, 291, 1769–1772; (b) Irie, M.;
Fukaminato, T.; Tamai, N.; Kawai, T. Nature 2002, 420, 759–760; (c) Tsujioka, T.;
Shimizu, M.; Ishihara, E. Appl. Phys. Lett. 2005, 87, 213506–213508; (d) Bianco,
A.; Bertarelli, C.; Gallazzi, M. C.; Zerbi, G.; Giro, E.; Molinari, E. Astron. Nachr.
2005, 326, 370–374; (e) Tsujiokka, T.; Iefuji, N.; Jiapaer, A.; Irie, M.; Nakamura,
S. Appl. Phys. Lett. 2006, 89, 222102–222104.
2. (a) Gilat, S. L.; Kawai, S. H.; Lehn, J.-M. J. Chem. Soc., Chem. Commun. 1993,
1439–1442; (b) Saika, T.; Irie, M.; Shimidzu, T. J. Chem. Soc., Chem. Commun.
1994, 2123–2124.
3. (a) Hanazawa, M.; Sumiya, R.; Horikawa, Y.; Irie, M. J. Chem. Soc., Chem.
Commun. 1992, 206–207; (b) Irie, M.; Miyatake, O.; Uchida, K. J. Am. Chem. Soc.

3310
R. Wang et al. / Tetrahedron Letters 52 (2011) 3306–3310
1992, 114, 8715–8716; (c) Irie, M.; Miyatake, O.; Uchida, K.; Eriguchi, T. J. Am.
Chem. Soc. 1994, 116, 9894–9900.
(s, 3H, –CH3), 2.34 (s, 3H, –CH3), 3.71 (s, 3H, –CH3), 6.61 (s, 1H, thiophene–H),
6.74 (d, 1H, benzene–H, J = 8.0 Hz), 6.79 (d, 2H, benzene–H, J = 8.0 Hz), 7.15 (t,
1H, benzene–H, J = 8.0 Hz), 7.33 (d, 1H, naphthalene–H, J = 8.0 Hz), 7.47 (t, 1H,
naphthalene–H, J = 8.0 Hz), 7.52 (d, 1H, naphthalene–H, J = 8.0 Hz), 7.79 (d, 1H,
naphthalene–H), 7.81 (m, 2H, naphthalene–H); 13C NMR (100 MHz, CDCl3,
TMS): d = 14.91, 20.42, 55.18, 110.48, 113.54, 117.89, 123.66, 125.00, 125.63,
126.99, 128.30, 128.59, 129.87, 130.04, 130.00, 131.67, 133.26, 135.68, 140.96,
4. (a) Irie, M.; Uchida, K.; Eriguchi, T.; Tsuzuki, H. Chem. Lett. 1995, 899–900; (b)
Uchida, K.; Irie, M. Chem. Lett. 1995, 969–970; (c) Uchida, K.; Matsuoka, T.;
Kobatake, S.; Yamaguchi, T.; Irie, M. Tetrahedron 2001, 57, 4559–4565.
5. (a) Uchida, K.; Matsuoka, T.; Sayo, K.; Iwamoto, M.; Hayashi, S.; Irie, M. Chem.
Lett. 1999, 835–836; (b) Heynderick, A.; Kaou, A. M.; Moustrou, C.; Samat, A.;
Guglielmetti, R. New J. Chem. 2003, 27, 1425–1432.
141.46; IR (KBr, m
, cmꢁ1): 678, 742, 767, 810, 872, 894, 982, 1046, 1101, 1132,
6. (a) Uchida, K.; Ishikawa, T.; Takeshita, M.; Irie, M. Tetrahedron 1998, 54, 6627–
6638; (b) Takami, S.; Irie, M. Tetrahedron 2004, 60, 6155–6161; (c) Giraud, M.;
Leaustic, A.; Charlot, M. –F.; Yu, P.; Cesario, M.; Philouze, C.; Pansu, R.;
Nakatani, K.; Ishow, E. New J. Chem. 2005, 29, 439–446.
7. Kuroki, L.; Takami, S.; Shibata, K.; Irie, M. Chem. Commun. 2005, 6005–6007.
8. Pu, S.; Yang, T.; Xu, J.; Chen, B. Tetrahedron Lett. 2006, 47, 6473–6477.
9. (a) Yagi, K.; Soong, C. F.; Irie, M. J. Org. Chem. 2001, 66, 5419–5423; (b) Yagi, K.;
Irie, M. Bull. Chem. Soc. Jpn. 2003, 76, 1625–1628.
1190, 1257, 1342, 1437, 1468, 1503, 1582, 1608, 1904, 3300, 3628. Data for 3o:
mp 131–132 °C; calcd for C28H17F9S (%): calcd C, 60.43; H, 3.08. Found: C,
60.51; H, 3.17; 1H NMR (400 MHz, CDCl3, ppm): d 2.25 (s, 3H, –CH3), 2.35 (s,
3H, –CH3), 6.84 (s, 1H, thiophene–H), 7.27 (s, 1H, benzene–H), 7.34 (m, 3H,
benzene–H, J = 8.0 Hz), 7.50 (m, 3H, naphthalene–H, J = 8.0 Hz), 7.69 (d, 1H,
naphthalene–H, J = 8.0 Hz), 7.82 (t, 2H, naphthalene–H, J = 8.0 Hz); 13C NMR
(100 MHz, CDCl3, TMS): d = 14.90, 20.43, 122.03, 123.36, 124.12, 124.70,
124.86, 125.18, 125.74, 125.92, 127.11, 128.41, 128.55, 128.90, 129.36, 130.14,
10. (a) Irie, M. Chem. Rev. 2000, 100, 1685–1716; (b) Tian, H.; Yang, S. J. Chem. Soc.
Rev. 2004, 33, 85–97.
11. Nakagawa, Hisako; Kawai, Shigekazu; Nakashima, Takuya; Kawai, Tsuyoshi
Org. Lett. 2009, 11, 1475–1478.
12. Yamaguchi, T.; Fujita, Y.; Irie, M. Chem. Commun. 2004, 1010–1011.
13. (a) Irie, M.; Sakemura, K.; Okinaka, M.; Uchida, K. J. Org. Chem. 1995, 60, 8305–
8309; (b) Pu, S. Z.; Yang, T. S.; Xu, J. K.; Shen, L.; Li, G. Z.; Xiao, Q.; Chen, B.
Tetrahedron 2005, 61, 6623–6629.
14. (a) Pu, S. Z.; Zheng, C. H.; Le, Z. G.; Liu, G.; Fan, C. B. Tetrahedron 2008, 64, 2576–
2585; (b) Liu, G.; Pu, S. Z.; Wang, X. M. Tetrahedron 2010, 66, 8862–8871; (c) Pu,
S. Z.; Li, M.; Liu, G.; Le, Z. G. Aust. J. Chem. 2009, 62, 464–474.
130.57, 131.22, 131.54, 131.91, 134.06, 135.45, 139.47, 142.00; IR (KBr, m,
cmꢁ1): 664, 691, 744, 774, 795, 811, 894, 979, 1049, 1131, 1168, 1195, 1276,
1328, 1443, 1509, 2384, 3300, 3675.
19. Li, Z. X.; Liao, L. Y.; Sun, W.; Xu, C. H.; Zhang, C.; Fang, C. J.; Yan, C. H. J. Phys.
Chem. C 2008, 112, 5190–5196.
20. Kawai, S.; Nakashima, T.; Atsumi, K.; Sakai, T.; Harigai, M.; Imamoto, Y.;
Kamikubo, H.; Kataoka, M.; Kawai, T. Chem. Mater. 2007, 19, 3479–3483.
21. (a) Fan, C. B.; Pu, S. Z.; Liu, G.; Yang, T. S. J. Photochem. Photobiol., A 2008, 194,
333–343; (b) Fan, C. B.; Pu, S. Z.; Liu, G.; Yang, T. S. J. Photochem. Photobiol., A
2008, 197, 415–425; (c) Liu, G.; Pu, S. Z.; Wang, X. M. J. Photochem. Photobiol., A
2010, 214, 230–240.
15. (a) Takeshita, M.; Ogawa, M.; Miyata, K.; Yamato, T. J. Phys. Org. Chem. 2003, 16,
148–151; (b) Uchida, K.; Nakamura, S.; Irie, M. Res. Chem. Intermed. 1995, 21,
861–876; (c) Liu, X. D.; Tong, Q. X.; Shi, M.; Zhang, F. S. Sci. China B 2006, 49,
517–521.
22. Kasatani, K.; Kambe, S.; Irie, M. J. Photochem. Photobiol., A 1999, 122, 11–15.
23. Liu, G.; Pu, S. Z.; Wang, X. M.; Liu, W. J.; Yang, T. S. Dyes Pigm. 2011, doi:
10.1016/j.dyepig.2010.11.001.
24. Tian, H.; Wang, S. Chem. Commun. 2007, 781–792.
16. (a) Pu, S. Z.; Fan, C. B.; Miao, W. J.; Liu, G. Tetrahedron 2008, 64, 9464–9470; (b)
Pu, S. Z.; Li, H.; Liu, G.; Liu, W. J. Tetrahedron Lett. 2010, 51, 3575–3579; (c) Pu, S.
Z.; Yan, P. J.; Liu, G.; Miao, W. J.; Liu, W. J. Tetrahedron Lett. 2011, 52, 143–147.
17. (a) Pu, S. Z.; Liu, G.; Li, G. Z.; Wang, R. J.; Yang, T. S. J. Mol. Struct. 2007, 833, 23–
29; (b) Pu, S. Z.; Fan, C. B.; Miao, W. J.; Liu, G. Dyes Pigm. 2009, 84, 25–35.
18. Data for 1o: Calcd for C27H18F6S (%): calcd C, 66.39; H, 3.71. Found: C, 66.46; H,
3.79; 1H NMR (400 MHz, CDCl3, ppm): d 2.13 (s, 3H, –CH3), 2.30 (s, 3H, –CH3),
6.81 (s, 1H, thiophene–H), 7.20 (d, 2H, benzene–H, J = 8.0 Hz), 7.33 (t, 2H,
benzene–H, J = 8.0 Hz), 7.42 (d, 1H, naphthalene–H), 7.42 (m, 3H, naphthalene–
H), 7.64 (d, 1H, benzene–H), 7.76 (t, 2H, naphthalene–H, J = 8.0 Hz); 13C NMR
(100 MHz, CDCl3, TMS): d = 14.85, 20.44, 123.38, 123.73, 124.97, 125.37,
125.52, 125.64, 126.96, 127.63, 128.31, 128.55, 128.85, 130.04, 130.47, 131.91,
25. Higashiguchi, K.; Matsuda, K.; Yamada, T.; Kawai, T.; Irie, M. Chem. Lett. 2000,
1358–1359.
26. Pu, S. Z.; Miao, W. J.; Cui, S. Q.; Liu, G.; Liu, W. J. Dyes Pigm. 2010, 87, 257–267.
27. (a) Tian, H.; Chen, B. Z.; Tu, H. Y.; Müllen, K. Adv. Mater. 2002, 14, 918–923; (b)
Kim, H. J.; Jang, J. H.; Choi, H.; Lee, T.; Ko, J.; Yoon, M.; Kim, H. J. Inorg. Chem.
2008, 47, 2411–2415; (c) Tomasulo, M.; Giordani, S.; Raymo, F. M. Adv. Funct.
Mater. 2005, 15, 787–794; (d) Fukaminato, T.; Sasaki, T.; Kawai, T.; Tamai, N.;
Irie, M. J. Am. Chem. Soc. 2004, 126, 14843–14849; (e) Irie, M.; Fukaminato, T.;
Sasaki, T.; Tamai, N.; Kawai, T. Nature 2002, 420, 759–760; (f) Giordano, L.;
Jovin, T. M.; Irie, M.; Jares-Erijman, E. A. J. Am. Chem. Soc. 2002, 124, 7481–7489.
28. (a) Tian, H.; Feng, Y. L. J. Mater. Chem. 2008, 18, 1617–1622; (b) Corredor, C. C.;
Huang, Z. L.; Belfield, K. D. Adv. Mater. 2006, 18, 2910–2914; (c) Frigoli, M.;
Mehl, G. H. Chem. Eur. J. 2004, 10, 5243–5250; (d) Chen, B. Z.; Wang, M. Z.; Wu,
Y. Q.; Tian, H. Chem. Commun. 2002, 1060–1061; (e) Zheng, H. Y.; Zhou, W. D.;
Yuan, M. J.; Yin, X. D.; Zuo, Z. C.; Ouyang, C. B.; Liu, H. B.; Li, Y. L.; Zhu, D. B.
Tetrahedron Lett. 2009, 50, 1588–1592.
133.31, 135.54, 140.88, 141.23; IR (KBr, m
, cmꢁ1): 690, 756, 774, 815, 871, 891,
984, 1031, 1134, 1191, 1272, 1339, 1445, 1470, 1505, 1554, 1599, 1739, 1944,
2862, 2926, 3062. Data for 2o: mp 89–90 °C; calcd for C28H20F6OS (%): calcd C,
64.86; H, 3.89. Found: C, 64.97; H, 3.95; 1H NMR (400 MHz, CDCl3, ppm): d 2.22