1320
C. He et al. / Tetrahedron Letters 51 (2010) 1317–1321
Figure 4. Optimized structures of 8PR-2F.
2009BAK64B00-03), Chinese Academy of Sciences (Grant No.
KGCX2-YW-118), ‘‘Bairen program” of CAS, and Shanghai Science
and Technology Committee (Grant No. 08JC1421900) for financial
supports.
Supplementary data
Supplementary data associated with this article can be found, in
References and notes
1. (a) Apostoluk, A.; Nunzi, J. M.; Perepichka, I. F.; Stepanenko, Z. V.; Serebryakov,
I. M. Chem. Phys. 2007, 331, 339–345; (b) Roncali, J.; Leriche, P.; Cravino, A. Adv.
Mater. 2007, 19, 2045–2060; (c) Li, Z. H.; Wong, M. S.; Fukutani, H.; Tao, Y. Org.
Lett. 2006, 8, 4271–4274; (d) Rathore, R.; Abdelwahed, S. H.; Guzei, I. A. J. Am.
Chem. Soc. 2003, 125, 8712–8713; (e) Geng, Y. H.; Trajkovska, A.; Culligan, S.
W.; Ou, J. J.; Chen, H. M. P.; Katsis, D.; Chen, S. H. J. Am. Chem. Soc. 2003, 125,
14032–14038; (f) Nakano, T.; Yade, T. J. Am. Chem. Soc. 2003, 125, 15474–
15484.
2. (a) Barberis, V. P.; Mikroyannidis, J. A. Synth. Met. 2006, 156, 1408–1414; (b)
Peng, Z. K.; Tao, S. L.; Zhang, X. H.; Tang, J. X.; Lee, C. S.; Lee, S. T. J. Phys. Chem. C
2008, 112, 2165–2169.
3. (a) Saragi, T. P. I.; Spehr, T.; Siebert, A.; Fuhrmann-Lieker, T.; Salbeck, J. Chem.
Rev. 2007, 107, 1011–1065; (b) Poriel, C.; Rault-Berthelot, J.; Barriere, F.;
Slawin, A. M. Z. Org. Lett. 2008, 10, 373–376; (c) Tang, S.; Liu, M. R.; Lu, P.;
Cheng, G.; Zeng, M.; Xie, Z. Q.; Xu, H.; Wang, H. P.; Yang, B.; Ma, Y. G.; Yan, D. H.
Org. Electron. 2008, 9, 241–252.
Figure 5. SEM image of drop-casted 8PR-2F particles.
carbazole-contained chromospheres arising from the free moving
of three alkyl chains. Both conformations exhibit a highly steric
three-dimensional (3D) structure, which is responsible for the iso-
tropic electronic properties of the devices during a solution-based
process. The 3D and rigid structure could assist in reducing the
intermolecular interaction in the solid state, as proved by their
spectroscopic data.
Inspired by their 3D structure, the self-organization behavior of
the dimmers was studied. When the solvent evaporated naturally
from the 4PR-2F and 8PR-2F solutions at room temperature, solid
powders with perfect sphere morphology (Fig. 5) were precipitated
from the solutions. And the size of the amorphous spheres was
tunable to some extent by a simple changing of the concentration.
However, no such spherical morphology was formed from 2PR-Cz
or 2PR-F solutions under the same condition. The detailed forma-
tion mechanism of the morphology structure is warrant to be
investigated.
4. Here, dimmer refers to 1,6-hexanyl bridged difluorene structure, as against
with no 1,6-hexanyl bridged fluorene monomer.
5. (a) Tao, S. L.; Peng, Z. K.; Zhang, X. H.; Wang, P. F.; Lee, C. S.; Lee, S. T. Adv. Funct.
Mater. 2005, 15, 1716–1721; (b) Cirpan, A.; Rathnayake, H. P.; Lahti, P. M.;
Karasz, F. E. J. Mater. Chem. 2007, 17, 3030–3036; (c) Tang, C.; Liu, F.; Xia, Y. J.;
Lin, J.; Xie, L. H.; Zhong, G. Y.; Fan, Q. L.; Huang, W. Org. Electron. 2006, 7, 155–
162.
6. (a) Promarak, V.; Ichikawa, M.; Sudyoadsuk, T.; Saengsuwan, S.; Jungsuttiwong,
S.; Keawin, T. Synth. Met. 2007, 157, 17–22; (b) Zhao, Z. J.; Xu, X. J.; Wang, F.; Yu,
G.; Lu, P.; Liu, Y. Q.; Zhu, D. B. Synth. Met. 2006, 156, 209–214; (c) Thomas, K. R.
J.; Velusamy, M.; Lin, J. T.; Chuen, C. H.; Tao, Y. T. Chem. Mater. 2005, 17, 1860–
1866.
7. Vyas, P. V.; Bhatt, A. K.; Ramachandraiah, G.; Bedekar, A. V. Tetrahedron Lett.
2003, 44, 4085–4088.
In summary, new intermolecular fluorene dimmers have 4- and
8-substituted pyrenyls in the fluorene rings have been synthesized.
These fluorene dimmers tend to form amorphous structure arising
from the high steric hindrances of the 3D molecular structure. DSC
results suggested the dimmers could be more suitable for making
stable films for organic electronic devices. Optical properties re-
vealed that the dimmers have higher molar extinction coefficients
and can prevent severe aggregation in film state. The cyclic voltam-
metric curves showed that the dimmers could be used as strong
electron-donating materials. And also the SEM data exhibited an
interesting self-organization behavior that deserved for further
study.
8. Compound 4PR-2F: A mixture of 2 (0.32 g, 0.26 mmol), 1-(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)pyrene (0.42 g, 1.3 mmol), potassium carbonate
(0.71 g, 5.2 mmol), and Pd(PPh3)4 (60 mg, 0.05 mmol) in 15 mL of toluene/
H2O (2:1, v/v) was degassed for 30 min and then heated to reflux for 36 h. The
mixture was extracted with CHCl3 and the organic layer was washed with
water and brine, and then dried over anhydrous MgSO4. The solvent was
removed and the residue was purified by column chromatography on silica gel,
and then recrystallized in CH2Cl2/ethanol to get slightly green solid (0.2 g, yield
45%). Mp 251.7–252.7 °C; 1H NMR (500 M, CDCl3, ppm) d 8.13 (m, 12H), 8.06–
7.92 (m, 24H), 7.87 (d, 4H, J = 9 Hz), 7.80 (d, 4H, J = 7.5 Hz), 7.54 (m, 8H), 7.30 (t,
4H, J = 7.5 Hz), 7.23 (d, 4H, J = 8 Hz), 7.12 (t, 4H, J = 7.5 Hz), 4.09 (t, 4H, J = 7 Hz),
1.97 (m, 8H), 1.66 (m, 4H), 1.17 (m, 4H), 1.11 (s, 8H), 0.88 (s, 8H); 13C NMR
(500 MHz, CDCl3, ppm)
d 150.876, 140.285, 139.972, 139.921, 138.107,
131.465, 130.885, 130.482, 129.512, 127.600, 127.392, 127.343, 125.948,
125.472, 125.224, 125.067, 125.035, 124.902, 124.763, 124.614, 122.711,
120.230, 118.601, 108.516, 55.244, 42.802, 40.326, 40.080, 29.836, 29.754,
28.733, 26.860, 24.101, 23.959; MALDI-TOF MS: m/z 1713.7. Anal. Calcd for
C132H100N2: C, 92.49; H, 5.88; N, 1.63. Found: C, 92.15; H, 5.60; N, 1.60.
Acknowledgments
Compound 8PR-2F:
A flask charged with 3 (0.32 g, 0.2 mmol), 1-(4,4,5,5-
tetramethyl-1,3,2-dioxaborolan-2-yl)pyrene (0.6 g, 1.86 mmol), potassium
carbonate (1.2 g, 8.7 mmol), Pd(PPh3)4 (57 mg, 0.05 mmol), and 21 mL of
toluene/H2O (2:1, v/v) was degassed for 30 min. The solution was heated to
reflux for 36 h, and then poured into 50 mL H2O and extracted with CHCl3. The
The authors are grateful to the National Natural Science Foun-
dation of China (Grant Nos. 60977067 and 50973128), the Ministry
of Science and Technology of China (Nos. 2007AA06A407 and