M. Iyoda. K. Kamada et al.
nyl)benzene and 15 in 51% yield. Method B also afforded 7 as a yellow
waxy solid in 76% yield. 1H NMR (400 MHz, CD2Cl2): d=7.58 (s, 3H),
7.43–7.40 (m, 6H), 7.38–7.34 (m, 6H), 7.30–7.26 (m, 3H), 7.24 (d, J=
4.0 Hz, 3H), 7.03 (d, J=4.0 Hz, 3H), 2.75–2.71 (m, 6H), 2.60–2.56 (m,
6H), 2.53–2.48 (m, 12H), 1.57–1.50 (m, 6H), 1.47–1.39 (m, 24H), 1.30–
1.23 (m, 18H), 0.93 (t, J=7.3 Hz, 9H), 0.83–0.78 ppm (m, 27H);
13C NMR (100 MHz, CD2Cl2): d=143.36, 143.04, 140.16, 139.13, 138.89,
138.40, 135.16, 133.35, 133.16, 130.46, 129.51, 129.37, 128.56, 127.69,
127.46, 125.62, 124.06, 121.87, 92.41, 84.17, 33.17, 33.13, 33.07, 32.92,
28.12, 27.88, 27.74, 27.31, 23.08, 22.98, 22.93, 22.88, 13.78, 13.67, 13.65,
13.62 ppm; MS (LDI-TOF) calcd for C114H132S9: m/z: 1788.78; found
1788.08; elemental analysis calcd (%) for C114H132S9: C 76.46, H 7.43;
found: C 76.35, H 7.46.
fibers of 3 melt at 1278C as determined by differential scan-
ning calorimetry (DSC) analysis to produce a supercooled
amorphous solid that no longer forms nanostructured poly-
morphs.
In summary, we have prepared a series of star-shaped oli-
gothiophenes 3, 5, and 7 with unique photophysical proper-
ties, such as a positive solvatochromism with increasing sol-
vent polarity, and two-photon absorption properties. Fur-
thermore, compound 3 with a central aromatic core and six
peripheral oligothiophene arms has an amphiphilic property
in organic solvents, resulting in the formation of nanostruc-
tures, such as fibrous polymorphs, owing to the lateral van
der Waals interaction of alkyl chains together with the
stacking interaction of the central p-frame. The moderate to
high solubilities and amorphous morphologies of 3, 5, and 7
seem to be more appropriate for constructing molecular
switches and devices.
Acknowledgements
This work was supported in part by a Grant-in-Aid for Scientific Re-
search from the JSPS. We would like to thank Prof. Motoko S. Asano
and Hirohisa Yoshida (Tokyo Metropolitan University) for their assis-
tance with VT UV/Vis measurements and VT XRD measurements. We
would also like to thank Dr. Eigo Isomura, Takeshi Ohmae, Masaki
Tateno, and Dr. Tomohiko Nishiuchi for experimental assistance.
Experimental Section
Oligothiophene 3: (Method A) Hexakis(trimethylsilylethynyl)benzene
(52 mg, 0.080 mmol) and K2CO3 (11 mg, 0.080 mmol) were dissolved in
THF (10 mL) and MeOH (10 mL), and the mixture was stirred for
30 min at room temperature. After dilution with Et2O (60 mL), the or-
ganic layer was washed with H2O three times. The organic layer was
dried over MgSO4, and the solution was concentrated by rotary evapora-
tion until the volume became about 15 mL. To the concentrated solution,
Keywords: fluorescence · nanostructures · nonlinear optics ·
star-shaped molecules · supramolecular chemistry
a solution of 15 (554 mg, 0.820 mmol), PdACHTNUTRGEN(UNG PPh3)4 (62 mg, 54 mmol), and
Nelson, P. Batail, J. Am. Chem. Soc. 1993, 115, 3752–3759;
zꢄlez, J. L. Segura, N. Martꢅn, Tetrahedron Lett. 2000, 41, 3083–
3086; g) C. A. Christensen, M. R. Bryce, A. S. Batsanov, J. Becher,
j) J. G. Rodrꢅguez, J. Esquivias, A. Lafuente, C. Dꢅaz, J. Org. Chem.
2003, 68, 8120–8128; k) H. S. Cho, H. Rhee, J. K. Song, C.-K. Min,
M. Takase, N. Aratani, S. Cho, A. Osuka, T. Joo, D. Kim, J. Am.
CuI (23 mg, 0.121 mmol) in THF (20 mL) and Et3N (2 mL) was added,
and the mixture was stirred at room temperature overnight. After adding
saturated aqueous NH4Cl solution, the aqueous layer was extracted three
times with CH2Cl2. The combined organic layer was dried over MgSO4,
and the solvent was evaporated. The crude product was subjected to
short column chromatography (SiO2: hexane/CH2Cl2 =2:1). Further pu-
rification by gel permeation chromatography gave 3 as an orange solid
(175 mg, 63%). Formation of this compound was not observed by Meth-
od B. Compound 3: M.p. 127.08C (DSC); 1H NMR (400 MHz, CDCl3):
d=7.50–7.45 (m, 18H), 7.42–7.38 (m, 12H), 7.34–7.31 (m, 6H), 7.14 (d,
J=3.4 Hz, 6H), 2.82–2.76 (m, 12H), 2.65–2.60 (m, 12H), 2.58–2.50 (m,
24H), 1.60–1.24 (m, 96H), 0.94–0.80 ppm (m, 72H); 13C NMR (100 MHz,
CDCl3): d=143.10, 142.69, 139.89, 139.72, 138.75, 138.06, 138.06, 135.10,
133.49, 130.64, 129.49, 129.32, 128.40, 127.68, 127.27, 125.92, 125.82,
122.04, 93.34, 92.15, 33.08(2C), 32.95, 32.79, 28.10, 27.80, 27.64, 27.24,
22.96, 22.90, 22.80(2C), 13.90, 13.82, 13.78, 13.73 ppm; MS (LDI-TOF)
calcd for C222H258S18: m/z: 3499.52; found 3499.56; elemental analysis
calcd (%) for C222H258S18: C 76.10, H 7.42; found: C 75.83, H 7.52.
Roquet, A. Ctavino, P. Leriche, O. AlꢃvÞque, P. Frꢆre, J. Roncali, J.
478–498; g) D. Cao, S. Dobis, C. Gao, S. Hillmann, H. Meier, Chem.
Int. Ed. 2000, 39, 3140–3142; c) P. H. J. Kouwer, W. J. Mijs, W. F.
Oligothiophene 5: (Method A) Compound 5 was prepared in a similar
manner to the preparation of 3, starting from 1,2,4,5-tetrakis(trimethylsi-
lylethynyl)benzene and 15 in 58% yield. By using Method B, compound
5 was also prepared as an orange-yellow waxy solid in 58% yield.
1H NMR (400 MHz, CDCl3): d=7.75 (s, 2H), 7.49–7.45 (m, 8H), 7.43–
7.38 (m, 8H), 7.36–7.30 (m, 8H), 7.09 (d, J=3.9 Hz, 4H), 2.81–2.75 (m,
8H), 2.66–2.60 (m, 8H), 2.59–2.50 (m, 16H), 1.60–1.43 (m, 40H), 1.35–
1.27 (m, 24H), 0.96 (t, J=7.3 Hz, 12H), 0.89–0.80 ppm (m, 36H);
13C NMR (100 MHz, CDCl3): d=143.08, 142.70, 139.81, 139.35, 138.80,
138.08, 135.12, 134.01, 133.11, 130.58, 129.47, 129.34, 128.40, 127.68,
127.28, 125.61, 124.54, 121.94, 92.37, 89.32, 33.07(2C), 32.97, 32.80, 28.10,
27.80, 27.65, 27.24, 23.00, 22.90, 22.80(2C), 13.91, 13.82, 13.78, 13.75 ppm;
MS (LDI-TOF) calcd for C150H174S12: m/z: 2359.03; found 2359.18; ele-
mental analysis calcd (%) for C150H174S12: C 76.28, H 7.43; found: C
76.20, H 7.42.
Oligothiophene 7: (Method A) Compound 7 was prepared in a similar
manner to the preparation of 3, starting from 1,3,5-tris(trimethylsilylethy-
12112
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Chem. Eur. J. 2010, 16, 12108 – 12113