Syntheses and properties of dumbbell-shaped POSS derivatives linked by luminescent π-conjugated units

Article abstract of DOI:10.1002/pola.26241

Dumbbell-shaped isobutyl-substituted 1,2-bis(4-vinylphenyl)acetylene-linked POSS (DA1), 9,10-bis(4-vinylphenyl)ethynyl)anthracene-linked POSS (DA2), and 5,5″-bis((4-vinyl)phenyl)ethynyl)-2,2':5'2″-terthiophene-linked POSS (DA3), and corresponding model co

Full text of DOI:10.1002/pola.26241

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Syntheses and Properties of Dumbbell-Shaped POSS Derivatives
Linked by Luminescent p-Conjugated Units
Hitoshi Araki, Kensuke Naka
Department of Chemistry and Materials Technology, Graduate School of Science and Technology, Kyoto
Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
Correspondence to: K. Naka (E-mail: kenaka@kit.ac.jp)
Received 24 March 2012; accepted 15 June 2012; published online
DOI: 10.1002/pola.26241
ABSTRACT: Dumbbell-shaped isobutyl-substituted 1,2-bis(4-
vinylphenyl)acetylene-linked POSS (DA1), 9,10-bis(4-vinylphe-
nyl)ethynyl)anthracene-linked POSS (DA2), and 5,500-bis((4-
vinyl)phenyl)ethynyl)-2,20:50200-terthiophene-linked POSS (DA3),
and corresponding model compounds were synthesized by
cross metathesis and Sonogashira reaction, and their film
formability, and thermal and optical properties were examined.
The dumbbell structures of the obtained compounds were con-
firmed by 1H-, 13C-, and 29Si-NMR and MALDI-TOF-MS analysis.
The dumbbell-shaped POSS compounds gave optically trans-
parent films. All the model compounds, however, formed opa-
que films. All the films were emissive under UV irradiation.
The dumbbell structures minimize longer wavelength shifts
and improve emission efficiency of the luminescent p-conju-
gated linker units in their solid states compared with the model
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compounds. 2012 Wiley Periodicals, Inc. J Polym Sci Part A:
Polym Chem 000: 000–000, 2012.
KEYWORDS: films;
inorganic
polymers;
luminescence;
transparency
INTRODUCTION Organic light-emitting dyes have been widely
studied as light emitting layers because of their various
potential applications such as organic light-emitting diodes
(OLED), solar cell devices, non-linear optical materials, and
optical sensor devices.1 However, the most dyes have poor
moldability, and lower emission efficiency at their solid state
than those in solution. Light-emitting hybrid materials are
easily synthesized by sol–gel reaction, and have attracted
much attention because of their excellent thermal, mechanical,
optical, and electrical properties derived from organic and
inorganic moieties.2 The hybridization also improves mold-
ability and emission efficiency by preventing aggregation of
dyes in inorganic matrix.3–8 For example, Boilot and co-
workers synthesized carbazole, oxadiazole, and dicyanomethy-
lene derivatives having triethoxysilyl groups, and examined
their OLED device performance as hole and electron transport
layers, and light-emitting layers by spin coating without vac-
uum deposition process.4,5 Carbonaro and coworkers tuned
formation of aggregates and emission efficiency of Rhodamine
6G in xerogel.6,7 Moreno and coworkers dispersed boron
dipyrromethene (BODIPY) dyes in hybrid matrix.8 However,
these hybrid materials require thermosetting process with
long reaction time and high thermal temperature. Chujo and
coworkers synthesized a hybrid material dispersed BODIPY
dyes using a microwave reactor to promote sol–gel reaction
at relatively low temperature.9
Polyhedral oligomeric silsesquioxane (POSS) compounds
have received extensive research attention as nanoscale
building blocks to form hybrid materials.10,11 The particu-
larly notable features of POSS compounds are rigid and
bulky structures, high thermal stability, and low dielectric
constant. Introduction of the rigid and bulky POSS moieties
in luminescent polymers or oligomers promotes their quan-
tum efficiencies in photoluminescence (PL) and electrolumi-
nescence (EL), due to suppression of self-quenching in their
solid state.12–21 For example, the quantum yields of poly-
fluorene and poly(p-phenylenevinylene) having POSS units in
their side chains are higher than those of corresponding
polymers without POSS.12–15 Several groups have shown
combination of POSS compounds with organic luminescent
dyes. Stilbene octa-substituted POSS derivatives attached
through p-conjugated linkers were synthesized by Laine and
co-workers via cross metathesis and Heck reactions. They
proposed that the POSS cores extend 3D conjugation of the
stilbene units in the excited state.16 Sellinger and coworkers
synthesized octavinyl-substituted POSS derivatives connect-
ing 4–16 luminescent substituents and examined their film
properties as light-emitting layers for OLED devices.17,18
However, no optical transparent films of a single luminescent
POSS compound have been reported.
We have reported that dumbbell and star-shaped POSS
derivatives linked by simple aliphatic chains formed optical
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SCHEME 1 Synthesis flow of IB7PA.
transparent films depend on their aliphatic chains.19,20 These
compounds gave optical transparent POSS films showing
thermoplastic properties due to decrease in their crystallin-
ity and formation of amorphous phase. In the previous
report we found that the linker parts of the dumbbell-
shaped POSS derivatives decreased their molecular mobility
units formed good optical transparent and light-emitting
films due to reduction their symmetries and molecular
mobilities.
RESULTS AND DISCUSSION
1
according to H-NMR analysis.20 Here, we report synthesis of
Syntheses and Characterization of Dumbbell-Shaped
POSS Derivatives and Model Compounds
(E)-2-(4-Ethynylphenyl)vinylheptaisobutyl-T8-silsesquioxane
(IB7PA) was used as a precursor for all the dumbbell-shaped
POSS derivatives linked by luminescent p-conjugated
linkers. IB7PA was synthesized from vinylheptaisobutyl-T8-
dumbbell-shaped POSS derivatives linked by luminescent
p-conjugated units. Although the dumbbell-shaped isobutyl-
substituted POSS compounds linked by the same aliphatic
chains gave no optical transparent films, the obtained dumb-
bell-shaped POSS derivatives linked by rigid p-conjugated
SCHEME 2 Syntheses of the dumbbell-shaped POSS derivatives.
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SCHEME 3 Syntheses of the model compounds.
silsesquioxane (IB7V1) via cross metathesis, Sonogashira
coupling, and deprotection reactions (Scheme 1). (E)-2-(4-
Bromophenyl)vinylheptaisobutyl-T8-silsesquioxane (IB7Br)
as a intermediate for IB7PA was also used as a precursor for
the dumbbell-shaped POSS derivatives.
compounds was very low except for M1. The dumbbell-
shaped POSS compounds have better processability for coat-
ing process than the model compounds due to their excellent
solubilities.
UV–Vis and PL Spectra in Solution
Reaction of IB7PA with IB7Br, 9,10-dibromoanthracene, and
5,500-dibromo-2,20:50,200-terthiophene by a Pd catalyst gave cor-
responding p-conjugated dumbbell-shaped POSS derivatives,
i.e., 1,2-bis(4-((E)-2-(heptaisobutyl-T8-silsesquioxanyl)vinyl)-
phenyl)acetylene (DA1), 9,10-bis((4-((E)-2-(heptaisobutyl-T8-
silsesquioxanyl)vinyl)phenyl)ethynyl)anthracene (DA2), and
5,500-bis((4-((E)-2-(heptaisobutyl-T8-silsesquioxanyl)vinyl)-
phenyl)ethynyl)-2,20:50200-terthiophene (DA3), respectively
(Scheme 2). All the products were purified by silica gel chro-
matography. The dumbbell structures of DA1, DA2, and DA3
Although UV–vis spectra of DA1, DA2, and DA3, respectively,
in THF were almost same as those of corresponding model
compounds, slightly red-shifts of the lowest energy absorp-
tion maximum (kmax) of the dumbbell-shaped POSS deriva-
tives compared with those of the corresponding model com-
pounds were observed (Fig. 1 and Table 2). The UV–vis
spectra of toluene and (p-tolyl)trimethoxysilane (TTMS) sug-
gest that the later showed slightly longer conjugation length
than the former judging from their absorption edges [Fig.
1(d) and Table 2]. These results indicate that the trimethoxy-
silyl group acts as an electron-donor group. The slightly
red-shifts of the dunmbbell-shaped POSS derivatives in the
UV–vis spectra were derived from the electron-donating trisi-
loxysilyl group. However, the electron withdrawing nature of
the caged structures cannot be ruled out. Fether and
coworkers suggested that a Si8O12 framework acted as an
electron withdrawing substituent and was equivalent to a
CF3 group according to 13C-NMR analysis and Hammett’s
rule.24 The HOMO–LUMO band gaps estimated from their
1
were supported by H-NMR, 13C-NMR, 29Si-NMR, and MALDI-
TOF-MS analysis. Purity of these compounds was confirmed
by sharp unimodal GPC traces, in which both unreacted raw
materials and oligomeric byproducts are barely noticeable.
To compare properties of the dumbbell-shaped POSS deriva-
tives, corresponding linker parts compounds (M1, M2, and
M3) as model compounds were synthesized by Sonogashira
coupling of 4-ethynylstyrene with 4-bromostyrene, 9,10-
dibromoanthracene, and 5,500-dibromo-2,20:50,200-terthiophene,
respectively (Scheme 3). The model compounds were puri-
fied by recrystallization for M1 or solvent washing for M2
and M3 due to their poor solubility to common solvents.
Although silyl-substituted model compounds at their termi-
nal position should be more precise than the present model
compounds, we failed to synthesize the former ones due to
synthetic difficulties.
TABLE 1 Solubilities of the Dumbbell-Shaped POSS
Derivatives and Model Compounds
Acetone THF EtOAc CHCl3 n-Hexane MeOH H2O
DA1
DA2
DA3
M1
þ
þ
þ
þ
6
6
þ
þ
þ
þ
6
6
þ
þ
þ
þ
6
6
þ
þ
þ
þ
6
6
þ
þ
þ
6
ꢀ
ꢀ
6
6
6
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Solubilities of the dumbbell-shaped POSS and model com-
pounds are summarized in Table 1. All the POSS derivatives
were soluble in aprotic polar solvents and nonpolar solvents
such as acetone, THF, n-hexane, and chloroform. Protic sol-
vents such as methanol and water hardly dissolved the
dumbbell-shaped POSS derivatives. Solubility of the model
M2
M3
þ, soluble; 6, partly soluble; and ꢀ, insoluble.
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FIGURE 1 UV–vis spectra of (a) M1 and DA1, (b) M2 and DA2, (c) M3 and DA3, and (d) toluene and TTMS in THF (M1: c ¼ 5.56 ꢁ
10ꢀ6 mol/L, DA1: c ¼ 1.83 ꢁ 10ꢀ6 mol/L, M2: c ¼ 7.80 ꢁ 10ꢀ6 mol/L, DA2: c ¼ 1.99 ꢁ 10ꢀ6 mol/L, M3: c ¼ 6.55 ꢁ 10ꢀ6 mol/L, DA3: c
¼ 1.83 ꢁ 10ꢀ6 mol/L, toluene: c ¼ 2.28 ꢁ 10ꢀ3 mol/L, TTMS: c ¼ 1.15 ꢁ 10ꢀ3 mol/L).
lower energy absorption edges (kedge) are summarized in
Table 2. The dumbbell-shaped POSS derivatives had nar-
rower band gaps than the model compounds. In particularly,
the narrowest band gap was observed on the case of DA1.
Film Formability and Optical Property in Film State
We studied film forming properties of the dumbbell-shaped
POSS derivatives and the model compounds on soda lime
TABLE 2 Data from UV–vis Absorptions of the Dumbbell-
Similar shaped and slightly red-shifted emission and excita-
tion spectra of the dumbbell-shaped POSS derivatives in THF
were observed compared with those of the corresponding
model compounds (Fig. 2). DA1 showed the largest red-shift
in the PL spectra similarly to the case of the UV–vis spec-
trum, and improve relative quantum yield compared with
that of M1 (Table 3). In the case of DA2 and DA3, no clear
increase of the relative quantum yield was observed com-
pared with the corresponding model compounds. Since the
linker parts of the dumbbell-shaped POSS derivatives
decreased their molecular mobility,23 the p-conjugated linker
parts are suppressed molecular mobility and non-radiative
transition by each terminal POSS moiety, especially in the
case of DA1.
Shaped POSS Derivatives and the Model Compounds in THF
kmax (nm)
kedge (nm)
Band Gapa (eV)
M1
319
355
374
504
508
491
494
277
281
2.88
2.74
2.03
2.02
2.09
2.07
3.70
3.64
DA1
M2
328
275,329,452
275,333,456
419
DA2
M3
DA3
Toluene
TTMS
a
421
261
261
HOMO–LUMO band gaps were obtained by kedge.
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FIGURE 2 PL spectra of (a) M1 and DA1, (b) M2 and DA2, and (c) M3 and DA3 in THF (M1: c ¼ 5.56 ꢁ 10ꢀ7 mol/L, DA1: c ¼ 3.66 ꢁ
10ꢀ7 mol/L, M2: c ¼ 7.80 ꢁ 10ꢀ7 mol/L, DA2: c ¼ 3.98 ꢁ 10ꢀ7 mol/L, M3: c ¼ 6.55 ꢁ 10ꢀ7 mol/L, DA3: c ¼ 3.66 ꢁ 10ꢀ7 mol/L).
glasses by spin coating of the coating solutions and subse-
quent baking at 100 ꢂC for 3 min using a hot plate. DA1,
DA2, and DA3 were dissolved in n-hexane and M1 was dis-
solved in CHCl3 at 3 wt % for the coating solutions. Since
the concentration of the coating solution for M2 and M3
were hardly controlled due to their low solubilities, satu-
rated solutions of less than 0.3 wt % in chloroform were
used. We found that DA1 formed a colorless transparent film
and DA2 and DA3 formed yellow-colored transparent films
(Fig. 3). However, opaque yellowish or brownish films were
formed in the cases of M1, M2, and M3. The absorbance in
the UV–vis spectrum of the film obtained from DA1 was less
than 0.01 in the visible region between 800 nm and 400 nm.
On the other hand, the film obtained from M1 showed a
marked increase in absorption in that region due to its opac-
ity [Fig. 4(a)]. The thickness of the opaque film obtained
from M1 should be similar to that of the DA1 film because
the coating conditions and solution concentration were the
same. The absorbance of the film obtained from M1 at 320
nm is significantly lower than that of the DA1 film. This
might be due to inhomogeneity of the former film. Because
the film thickness of the opaque film obtained from M2 and
M3 should be less than 1/10 of those of the films obtained
from DA2 and DA3, vertical scales in the UV–vis spectra of
the films obtained from M2 and M3 were magnified by ten
times larger than the original scales [Fig. 4(b)]. The absorb-
ance of the yellow-colored transparent films obtained from
DA2 and DA3 were also less than 0.01 in their colorless
regions. On the other hand, those of the opaque film
TABLE 3 Relative Quantum Yields of the Dumbbell-Shaped
POSS Derivatives and the Model Compounds
kex
U
M1
323
323
407
407
407
407
0.882
1.033
0.677
0.640
0.237
0.250
DA1
M2
DA2
M3
DA3
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FIGURE 3 Appearance of the films obtained from (a) M1, (b) M2, (c) M3, (d) DA1, (e) DA2, and (f) DA3 on glasses.
obtained from M2 and M3 significantly increased in those
regions. SEM images of the film surfaces are shown in
Figure 5. The surfaces of all the model compounds are rough
and rugged [Fig. 5(a–c)]. All the dumbbell-shaped POSS
compounds show smooth surfaces, although some crystal
particles were dispersed on the films [Fig. 5(d–f)]. These
results indicate that the film states of the dumbbell-shaped
POSS compounds are mixture of an amorphous state (the
smooth area) and a crystal state (the particle area). The
amorphous state of the smooth area and the crystal state of
the particle area were supported by dark image and bright
spots image, respectively, at crossed nicols condition by
polarized-light microscope [Fig. 6(d–f)]. On the other hand,
all the model compounds showed crystal phase [Fig. 6(a–c)].
shaped POSS derivatives linked by the rigid p-conjugated
linkers formed optical transparent films. The rigid linkers
tend to reduce crystallinity of the POSS derivatives compared
with the flexible linkers.
Appearances of the films obtained from M1 and DA1 under
UV irradiation (352 nm) show bluish green and blue emis-
sions, respectively (Fig. 7). Those from M2 and DA2 show or-
ange and yellow emissions, respectively. Those from M3 and
DA3 show orange and greenish yellow emissions, respec-
tively. These results suggest that emission wavelengths were
large different between the dumbbell-shaped POSS deriva-
tives and the corresponding model compounds unlike those
in the solution states. The wavelength of the emission max-
ima of the films obtained from DA1, DA2, and DA3 were
shorter than those of the corresponding model compounds
(Fig. 8 and Table 4). The emission intensities of the dumb-
bell-shaped POSS compounds, especially DA2 and DA3, were
higher than those of the model compounds, under employing
Although the trifluoropropyl-substituted dumbbell-shaped
POSS compounds linked by flexible simple aliphatic chains
formed optical transparent films,22 the dumbbell-shaped iso-
butyl-substitute.23 On the other hand, the present dumbbell-
FIGURE 4 UV–vis spectra of the films obtained from (a) M1 and DA1, (b) M2, M3, DA2, and DA3 on glasses.
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FIGURE 5 SEM images of the films obtained from (a) M1, (b) M2, (c) M3, (d) DA1, (e) DA2, and (f) DA3 on glasses.
same amount of powder samples. Generally, solid state emis-
sion maxima of usual photoluminescent compounds are red-
shifted and decrease their emission efficiency compared with
their solutions. Although the dumbbell-shaped structures still
show some red-shifts in the film states, the present results
suggest that the dumbbell structures reduce longer wave-
length shifts and improve emission efficiency of the lumines-
cent p-conjugated linker units in their solid states.
Thermal Property
Thermal stabilities of the dumbbell-shaped POSS derivatives
and the model compounds were studied by thermogravimet-
ric analysis (TGA) under a nitrogen atmosphere (Fig. 9). Ini-
tial decomposition temperatures of the POSS derivatives
were higher than those of the corresponding model com-
pounds [Fig. 9(b)]. DA1, DA2, and DA3 showed 1 wt %
losses at 268 ꢂC, 372 ꢂC, and 282 ꢂC, respectively. These
FIGURE 6 Polarized-light microscope images of the films obtained from (a) M1, (b) M2, (c) M3, (d) DA1, (e) DA2, and (f) DA3 on
glasses.
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FIGURE 7 Appearance of the films obtained from M1–M3 and DA1–DA3 on glasses under blue light irradiation.
FIGURE 8 PL spectra of (a) M1 and DA1, (b) M2 and DA2, and (c) M3 and DA3 in the film states.
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TABLE 4 Result of PL Spectra at Solution and Film States
kmax (nm)
EXPERIMENTAL
Materials
All solvents and chemicals used here were obtained as rea-
gent-grade quality and used without further purification. All
the reactions were performed under a nitrogen atmosphere.
4-Ethynylstyrene was synthesized by previous reported
method using PdCl2(PPh3)2 catalyst.25
PLEm. (solution)
PLEm. (film)
Dka (nm)
M1
DA1
M2
DA2
M3
DA3
a
346, 364
358, 377
489
478
132
43
69
50
91
34
401
558, 569
542
Measurements
492
1H-(400 MHz), 13C-(100 MHz), and 29Si-(80MHz) NMR spec-
tra were recorded on a BRUKER PDX-300. MALDI-TOF-MS
was recorded on a BRUKER Autoflex II instrument. FAB-HR-
MS was recorded on a JEOL JMS-700. Fourier transform
infrared (FTIR) spectra were obtained on a JASCO FT/IR-
4100 spectrometer using KBr pellets. UV–vis spectra were
recorded on a JASCO spectrophotometer V-670 KKN. Fluores-
cence emission and excitation spectra were recorded on a
PerkinElmer LS 50B luminescence spectrometer. Differential
scanning calorimetry (DSC) was recorded on a TA Instru-
ments 2920 Modulated DSC. Thermogravimetric analysis
(TGA) was measured on a TA Instruments Hi-Res Modulated
TGA 2950 thermogravimetric analyzer. Polarized-light micro-
scope images of the films were obtained by a Nikon Opti-
phot-Pol polarizing microscope.
484
575
486
520
PLEm.(solution)ꢀPLEm.(film).
temperatures were higher than those of M1 (134 ꢂC), M2
(174 ꢂC), and M3 (184 ꢂC), respectively. These results indi-
cate that thermal stabilities of the POSS derivatives were
higher than those of the corresponding model compounds.
Differential scanning calorimeter (DSC) traces of the dumb-
bell-shaped POSS derivatives in their film states are
showed in Figure 10. To avoid unexpected phase transition
under a cooling process, the DSC measurement ranges of
the films were started from room temperature. DA3
showed a glass transition at 70 ꢂC, crystallization at 136
ꢂC, and melting at around 200 ꢂC. These observations indi-
cate that the film obtained from DA3 consisted of an amor-
phous phase. Although the films obtained from DA1 and
DA2 showed no clear glass-transitions in the range of 30
ꢂC to 300 ꢂC, they showed crystallizations at 210 ꢂC and
197 ꢂC, respectively. These crystallization behaviors sug-
gested that the films obtained from DA1 and DA2 also con-
sisted of amorphous phases. These assumptions were sup-
ported by the polarized-light microscope observation
described earlier.
(E)-2-(4-Bromophenyl)vinylheptaisobutyl-T8-
silsesquioxane (IB7Br)
Vinylheptaisobutyl-T8-silsesquioxane (IB7V1) (3.5 g, 4.15
mmol) and the first generation Grubbs catalyst (0.068 g,
0.083 mmol) were charged into a Schlenk flask at room tem-
perature under N2 atmosphere. Dry dichloromethane (4.9
mL) and p-bromostyrene (1.63 mL, 12.4 mmol) were ꢂadded
to the flask by syringe and magnetically stirred at 30 C. Af-
ter 48 h, the first generation Grubbs catalyst (0.034 g, 0.041
ꢂ
mmol) was added and further stirred at 30 C for 24 h. The
reaction solution was poured into MeOH (100 mL) and
FIGURE 9 TGA thermograms of (a) of M1–M3 and DA1–DA3 at a ramp rate of 10 ꢂC/min in N2 flow. Expanded curves (b) upper
95% of weight residue.
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13C NMR (CDCl3, 100 MHz): d 147.15, 137.61, 132.16,
126.57, 123.23, 119.85, 104.97, 95.34, 25.72, 23.88, 23.87,
22.51, 22.44. 29Si NMR (CDCl3, 80 MHz): d ꢀ67.39, ꢀ67.83,
ꢀ80.16. FT-IR (KBr): m ¼ 2954, 2927, 2907, 2872, 2156,
1508, 1465, 1402, 1383, 1366, 1330, 1229, 1105, 865, 839,
755, 742 cmꢀ1
.
FAB-HR-MS (m/z, [M]þ): 1014.3417
(calc.);1014.3451 (observed).
(E)-2-(4-Ethynylphenyl)vinylheptaisobutyl-T8-
silsesquioxane (IB7PA)
IB7TMS (1.5 g, 1.5 mmol), K2CO3 (0.042 g, 0.3 mmol), MeOH
(5 mL), and THF (5 mL) were charged into a round-bot-
tomed flask at room temperature under air atmosphere and
magnetically stirred at room temperature for 2 h. The reac-
tion solution was added diethylether, and washed with dis-
tilled water and with saturated NH4Cl (2 ꢁ 50 mL). The so-
lution was dried over MgSO4, filtered, and concentrated. The
resultant solid was purified by recrystallization with ethyl
acetate/MeOH ¼ 5/5 solution.
FIGURE 10 DSC traces of DA1–DA3 in film state at a ramp rate
of 10 ꢂC/min in N2 flow for the whole temperature range. These
films were prepared by baking the coating solution in alumi-
num pan at 100 ꢂC for measuring DSC.
1
Yield: 78%. H NMR (CDCl3, 400 MHz): d 7.46 (d, J ¼ 8.3 Hz,
2H), 7.39 (d, J ¼ 8.3 Hz, 2H), 7.14 (d, J ¼ 19.1 Hz, 1H), 6.16
(d, J ¼ 19.1 Hz, 1H), 3.13 (s, 1H), 1.88 (m, 7H), 0.98 (d, J ¼
6.6 Hz, 18H), 0.96 (d, J ¼ 6.6 Hz, 24H), 0.65 (d, J ¼ 7.1 Hz,
6H), 0.62 (d, J ¼ 7.0 Hz, 8H).
filtered by suction filtration. The crude product was washed
by MeOH and purified by silica gel column chromatography
(n-hexane). The stereo conformation of the product was E
13C NMR (CDCl3, 100 MHz): d 147.02, 137.80, 132.34,
126.65, 122.17, 120.19, 83.56, 78.12, 25.72, 23.88, 23.86,
22.50, 22.44. 29Si NMR (CDCl3, 80 MHz): d ꢀ67.38, ꢀ67.83,
ꢀ80.23. FT-IR (KBr): m ¼ 2954, 2932, 2906, 2878, 1464,
1400, 1384, 1367, 1331, 1230, 1105, 840, 741 cmꢀ1. FAB-
HR-MS (m/z, [M]þ): 942.3031 (calc.);942.2982 (observed).
1
determined by H-NMR.
1
Yield: 68%. H NMR (CDCl3, 400 MHz): d 7.47 (d, J ¼ 8.4 Hz,
2H), 7.30 (d, J ¼ 8.4 Hz, 2H), 7.10 (d, J ¼ 19.1 Hz, 1H), 6.12
(d, J ¼ 19.1 Hz, 1H), 1.88 (m, 7H), 0.97 (d, J ¼ 6.6 Hz, 18H),
0.96 (d, J ¼ 6.6 Hz, 24H), 0.65 (d, J ¼ 7.0 Hz, 6H), 0.62 (d, J
¼ 7.1 Hz, 8H).
13C NMR (CDCl3, 100 MHz): d 146.66, 136.56, 131.69,
128.27, 122.61, 119.67, 25.71, 23.88, 23.86, 22.50, 22.43.
29Si NMR (CDCl3, 80 MHz): d ꢀ67.39, ꢀ67.83, ꢀ80.17. FT-IR
(KBr): m ¼ 2954, 2926, 2906, 2870, 1610, 1486, 1464, 1400,
1383, 1367, 1332, 1230, 1105, 1039, 1010, 989, 952, 839,
782, 742 cmꢀ1. FAB-HR-MS (m/z, [Mþ H]þ): 997.2205
(calc.); 997.2209 (observed).
1,2-Bis(4-((E)-2-(heptaisobutyl-T8-silsesquioxanyl)vinyl)-
phenyl)acetylene (DA1)
IB7PA (0.200 g, 0.21 mmol), IB7Br (0.199 g, 0.21 mmol),
PdCl2(PPh3)2 (8.9 mg, 0.013 mmol) and CuI (0.0024 g, 0.013
mmol) were charged into a Schlenk flask at room tempera-
ture under N2 atmosphere. Dry toluene (0.42 mL) and trie-
thylamine (0.21 mL) were ꢂadded to the flask by syringe and
magnetically stirred at 50 C for 24 h. The reaction solution
was quenched by filtering through each 1 cm Celite and
silica pad, and purified by silica gel column chromatography
(n-hexane gradient to n-hexane/ethyl acetate ¼ 99.5/0.5).
(E)-2-(4-Trimethylsilylethynylphenyl)vinylheptaisobutyl-
T8-silsesquioxane (IB7TMS)
IB7Br (2.6 g, 2.6 mmol), Pd2(dba)3 (0.0596 g, 0.065 mmol),
Pd(PtBu3)2 (0.0665 g, 0.13 mmol), and CuI (0.0496 g, 0.26
mmol) were charged into a Schlenk flask at room tempera-
ture under N2 atmosphere. Dry dioxane (5.2 mL) and trie-
thylamine (0.73 mL, 5.2 mmol) were added to the flask by
1
Yield: 42%. H NMR (CDCl3, 400 MHz): d 7.51 (d, J ¼ 8.3 Hz,
4H), 7.42 (d, J ¼ 8.4 Hz, 4H), 7.16 (d, J ¼ 19.1 Hz, 2H), 6.17
(d, J ¼ 19.1 Hz, 1H), 1.87 (m, 14H), 0.98 (d, J ¼ 6.6 Hz,
36H), 0.97 (d, J ¼ 6.6 Hz, 48H), 0.66 (d, J ¼ 7.0 Hz, 12H),
0.62 (d, J ¼ 7.1 Hz, 16H).
ꢂ
syringe and magnetically stirred at 25 C for 24 h. The reac-
tion solution was quenched by filtering through 1 cm Celite
and silica pad, and purified by silica gel column chromatog-
raphy (n-hexane).
13C NMR (CDCl3, 100 MHz): d 147.15, 137.49, 131.80,
126.74, 123.74, 119.82, 104.97, 90.50, 25.72, 23.88, 23.86,
22.51, 22.45. 29Si NMR (CDCl3, 80 MHz): d ꢀ67.38, ꢀ67.82,
ꢀ80.13. FT-IR (KBr): m ¼ 2954, 2930, 2905, 2893, 2871,
1606, 1515, 1465, 1402, 1383, 1366, 1333, 1229, 1100,
1075, 838, 744 cmꢀ1. MALDI-TOF-MS (m/z, [M]þ): 1858.59
(calc.); 1858.81 (observed).
1
Yield: 98%. H NMR (CDCl3, 400 MHz): d 7.43 (d, J ¼ 8.3 Hz,
2H), 7.36 (d, J ¼ 8.3 Hz, 2H), 7.13 (d, J ¼ 19.2 Hz, 1H), 6.14
(d, J ¼ 19.1 Hz, 1H), 1.88 (m, 7H), 0.98 (d, J ¼ 6.6 Hz, 18H),
0.96 (d, J ¼ 6.6 Hz, 24H), 0.65 (d, J ¼ 7.0 Hz, 6H), 0.62 (d, J
¼ 7.0 Hz, 8H), 0.25 (s, 9H).
10
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9,10-Bis((4-((E)-2-(heptaisobutyl-T8-silsesquioxanyl)-
vinyl)phenyl)ethynyl)anthracene (DA2)
DA2 was synthesized from IB7PA and 9,10-dibromoanthra-
cene (0.5 equiv. for IB7PA) in a similar manner to DA1.
Yield: 38%. 1H NMR (CDCl3, 400 MHz): d 8.70 (m, 4H), 7.74 (d,
J ¼ 8.3 Hz, 4H), 7.66 (m, 4H), 7.50 (d, J ¼ 8.2 Hz, 4H), 6.78 (m,
2H), 5.86 (d, J ¼ 17.6 Hz, 2H), 5.36 (d, J ¼ 10.9 Hz, 2H).
13C NMR (CDCl3, 100 MHz): d 137.89, 136.26, 132.09,
131.88, 127.27, 126.85, 126.39, 122.65, 118.49, 115.08,
102.58, 87.27. FT-IR (KBr): m ¼ 3075, 3056, 3038, 3003,
2983, 2195, 1824, 1793, 1735, 1623, 1598, 1509, 1403,
1276, 1240, 1204, 1181, 1158, 1146, 1113, 1025, 991, 912,
1
Yield: 58%. H NMR (CDCl3, 400 MHz): d 8.70 (m, 4H), 7.76
(d, J ¼ 8.3 Hz, 4H), 7.66 (m, 4H), 7.53 (d, J ¼ 8.4 Hz, 4H),
7.23 (d, J ¼ 19.3 Hz, 2H), 6.24 (d, J ¼ 19.2 Hz, 2H), 1.90 (m,
14H), 1.00 (d, J ¼ 6.6 Hz, 36H), 0.98 (d, J ¼ 6.6 Hz, 36H),
0.97 (d, J ¼ 6.6 Hz, 12H), 0.68 (d, J ¼ 7.0 Hz, 12H), 0.63 (d,
J ¼ 7.1 Hz, 12H), 0.62 (d, J ¼ 7.1 Hz, 4H).
843, 758, 636 cmꢀ1
.
5,500-Bis((4vinylphenyl)ethynyl)-2,20:50200-terthiophene
(M3)
M3 was synthesized from 4-ethynylstyrene and 5,500-
dibromo-2,20:50,200-terthiophene (0.5 equiv. for p-ethynylstyr-
ene) in a similar manner to DA1 except for using THF as sol-
vent and purified by washed with acetone.
13C NMR (CDCl3, 100 MHz): d 147.13, 137.89, 132.11,
131.89, 127.27, 126.95, 126.90, 123.49, 120.13, 118.50,
102.55, 87.70, 25.74, 23.91, 23.87, 22.52, 22.47. 29Si NMR
(CDCl3, 80 MHz): d ꢀ67.35, ꢀ67.81, ꢀ67.83, ꢀ80.15. FT-IR
(KBr): m ¼ 2955, 2934, 2905, 2879, 1508, 1464, 1402, 1364,
1329, 1228, 1102, 866, 838, 756 cmꢀ1. MALDI-TOF-MS (m/z,
[M]þ): 2058.65 (calc.); 2058.84 (observed).
1
Yield: 37%. H NMR (CDCl3, 400 MHz): d 7.47 (d, J ¼ 8.4 Hz,
2H), 7.40 (d, J ¼ 8.4 Hz, 2H), 7.18 (d, J ¼ 3.8 Hz, 2H), 7.11
(s, 2H), 7.08 (d, J ¼ 3.8 Hz, 2H), 6.71 (m, 2H), 5.80 (d, J ¼
17.6 Hz, 2H), 5.31 (d, J ¼ 10.8 Hz, 2H).
5,500-Bis((4-((E)-2-(heptaisobutyl-T8-silsesquioxanyl)-
vinyl)phenyl)ethynyl)-2,20:50200-terthiophene (DA3)
DA3 was synthesized from IB7PA and 5,500-dibromo-
2,20:50,200-terthiophene (0.5 equiv. for IB7PA) in a similar
manner to DA1.
13C NMR (Tetrahydrofuran-d8, 100 MHz): d 139.16, 138.94,
137.20, 136.91, 134.03, 127.16, 126.15, 124.95, 123.15,
122.91, 115.19, 95.39, 83.73. FT-IR (KBr): m ¼ 3085, 3066,
3003, 2195, 1623, 1599, 1515, 1439, 1403, 1276, 1182,
Yield: 37%. 1H NMR (CDCl3, 400 MHz): 7.49 (d, J ¼ 8.4 Hz,
4H), 7.43 (d, J ¼ 8.4 Hz, 4H), 7.19 (d, J ¼ 3.9 Hz, 2H), 7.16
(d, J ¼ 19.3 Hz, 2H), 7.11 (s, 2H), 7.09 (d, J ¼ 3.8 Hz, 2H),
6.18 (d, J ¼ 19.2 Hz, 2H), 1.88 (m, 14H), 0.98 (d, J ¼ 6.6 Hz,
36H), 0.97 (d, J ¼ 6.6 Hz, 48H), 0.66 (d, J ¼ 7.0 Hz, 12H),
0.62 (d, J ¼ 7.0 Hz, 16H).
1113, 1062, 1043, 992, 906, 857, 843, 798 cmꢀ1
.
Preparation of Coating Solutions and Coated Film
The coating solutions of the dumbbell-shaped POSS deriva-
tives and the model compounds were prepared by dissolving
DA1, DA2, DA3, and M1 in hexane or CHCl3 at 3 wt %. All
the coating solutions were filtrated through a 0.45 lm pore
size membrane filter made with polypropylene. The coating
solutions were spin-coated on a soda lime glass at around
200 rpm and subsequently baked at 100 ꢂC for 3 min on a
hot plate. The concentration of M2 and M3 was much less
than 0.3 wt % in CHCl3 due to their low solubilities.
13C NMR (CDCl3, 100 MHz): d 147.07, 138.43, 137.67,
136.11, 132.97, 131.55, 126.79, 124.95, 123.74, 122.86,
122.24, 120.03, 94.62, 83.74, 25.72, 23.88, 23.86, 22.51,
22.45. 29Si NMR (CDCl3, 80 MHz): d ꢀ67.38, ꢀ67.83,
ꢀ80.19. FT-IR (KBr):m ¼ 2954, 2930, 2904, 2868, 1603,
1465, 1401, 1382, 1365, 1334, 1230, 1100, 836, 791, 758,
738 cmꢀ1. MALDI-TOF-MS (m/z, [M]þ): 2128.55 (calc.);
2128.80 (observed).
Relative Quantum Yield
Relative quantum yield was calculated from the following
equation (eq 1).26 Anthracene (UST ¼ 0.3 in Ethanol. For DA1
and M1)26 and bis(phenylethynyl)anthracene (UST ¼ 0.85 in
Toluene. For DA2, DA3, M2, and M3)27 were used as standard
substances. The refractive indices of THF, toluene, and ethanol
were applied to 1.4040, 1.4978, and 1.3623, respectively.
1,2-Bis(4-vinylphenyl)acetylene (M1)
M1 was synthesized from 4-ethynylstyrene and 4-bromostyr-
ene in a similar manner to DA1 and purified by recrystalliza-
tion with n-hexane. Yield: 51%.
1H NMR (CDCl3, 400 MHz): d 7.49 (d, J ¼ 8.3 Hz, 2H), 7.39
(d, J ¼ 8.3 Hz, 2H), 6.71 (m, 2H), 5.78 (d, J ¼ 17.6 Hz, 2H),
5.30 (d, J ¼ 10.9 Hz, 2H).
R1
ðk Þ ꢁ UST (1)
2
nS
1 ꢀ 10ꢀA
ST
E
IF;SðkE; kFÞd kF
0
R
US ¼
2 ꢁ
ꢁ
1 IF;STðkE; kFÞd kF
1 ꢀ 10ꢀA ðk Þ
S
E
nST
0
13C NMR (CDCl3, 100 MHz): d 137.42, 136.24, 131.76,
126.17, 122.53, 114.76, 90.12. FT-IR (KBr): m ¼ 3083, 3060,
3035, 3002, 2982, 1919, 1818, 1697, 1624, 1597, 1516,
1403, 1316, 1277, 1203, 1179, 1113, 1014, 993, 970, 908,
where U ¼ relative quantum yield; n ¼ refractive index of
solvent; I ¼ emission intensity; A ¼ absorbance; k ¼ wave-
length; E ¼excitation; F ¼ fluorescence; S ¼ sample; and
ST ¼ standrard substance.
843, 735 cmꢀ1
.
Measurement of Absorbance Edge and Band Gap
9,10-Bis((4-vinylphenyl)ethynyl)anthracene (M2)
Normalized UV–vis spectra were differentiated with
respected to wavelength. kedge is the longest wavelength at
which differential of normalized absorbance is over 0.0025.
Band gap was estimated according to the following equation,
M2 was synthesized from 4-ethynylstyrene and 9,10-dibro-
moanthracene (0.5 equiv. for p-ethynylstyrene) in a similar
manner to DA1 and purified by washed with ethyl acetate.
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4 Morais, T. D.; Chaput, F.; Lahlil, K.; Boilot, J. P. Adv. Mater.
1999, 11, 107–112.
E (eV) ¼ hc/ek (h ¼ Plank’s Constant, c ¼ velocity of light,
e ¼ elementary electric charge).
5 Morais, T. D.; Chaput, F.; Boilot, J. P.; Lahlil, K.; Darracq, B.;
ꢀ
CONCLUSIONS
Levy, Y. Adv. Mater. Opt. Electron. 2000, 10, 69–79.
6 Anedda, A.; Carbonaro, C. M.; Corpino, R.; Ricci, P. C.; Grandi,
S.; Mustarelli, P. C. J. Non-Cryst. Solids 2007, 353, 481–485.
Dumbbell-shaped POSS derivatives linked by the p-conju-
gated units and the corresponding model compounds were
synthesized by cross metathesis and Sonogashira reaction,
and their optical and thermal properties were studied. The
7 Carbonaro, C. M. J. Photochem. Photobiol. A: Chem. 2011,
222, 56–63.
8 Garc´ıa, O.; Garrido, L.; Sastre, R.; Costela, A.; Moreno, I. G.
Adv. Funct. Mater. 2008, 18, 2017–2025.
1
structures of all the POSS derivatives were confirmed by H-,
13C-, 29Si-NMR spectra, and MALDI-TOF-MS analysis. DA1
had higher relative quantum yield than M1 in solution due
to suppression of the mobility and non-radiative transition
by each terminal POSS moiety. All the dumbbell-shaped POSS
compounds formed the optical transparent films by spin
9 Kajiwara, Y.; Nagai, A.; Chujo, Y. Bull. Chem. Soc. Jpn. 2011,
84, 471–481.
10 David, B. C.; Paul, D. L.; Franck, R. Chem. Rev. 2010, 110,
2081–2173.
11 Laine, R. M. J. Mater. Chem. 2005, 15, 3725–3744.
ꢂ
coating and subsequent baking at 100 C. All the model com-
12 Lee, J. H.; Cho, H. J.; Jung, B. J.; Cho, N. S.; Shim, K. H.
Macromolecules 2004, 37, 8523–8529.
pounds, however, formed opaque films. The simple flexible
aliphatic chain linked dumbbell-shaped POSS derivatives sub-
stituted isobutyl groups previously reported formed no opti-
cal transparent films.20 These results indicate that the rigid
linkers tend to decrease crystallinity of the POSS derivatives
compared with the flexible linkers. The SEM and polarized-
light microscopic observations and the DSC analysis sug-
gested that the dumbbell-shaped POSS compounds consisted
of amorphous phased. These obtained films emitted under
UV irradiation. The dumbbell structures reduced the longer
wavelength shifts and improve emission efficiency in their
solid states. The present dumbbell-shaped POSS derivatives
linked by the p-conjugated linkers are not only to enhance
emitting property, but also are regarded as new amorphous
luminescent molecules processable by spin coating.
13 Chou, C. H.; Hsu, S. L.; Yeh, S. W.; Wang, H. S.; Wei, K. H.
Macromolecules 2005, 38, 9117–9123.
14 Chou, C. H.; Hsu, S. L.; Dinakaran, K.; Chiu, M.Y.; Wei, K. H.
Macromolecules 2004, 37, 745–751.
15 Lin, W. J.; Chen, W. C.; Wu, W. C.; Niu, Y. H.; Jen, A. K. Y.
Macromolecules 2004, 37, 2335–2341.
16 Sulaiman, S.; Bhaskar, A.; Zhang, J.; Guda, R.; Goodson, T.,
III; Laine, R. M. Chem. Mater. 2008, 20, 5563–5573.
17 Lo, M. Y.; Zhen, C.; Lauters, M.; Jabbour, G. E.; Sellinger, A.
J. Am. Chem. Soc. 2007, 129, 5808–5809.
18 Lo, M. Y.; Ueno, K.; Tanabe, H.; Sellinger, A. Chem. Rec.
2006, 6, 157–168.
19 Ren, X.; Sun, B.; Tsai, C.-C.; Tu, Y.; Leng, S.; Li, K.; Kang, Z.;
Van Horn, R. M.; Li, X.; Zhu, M.; Wesdemiotis, C.; Zhang, W.-
B.; Cheng, S. Z. D. J. Phys. Chem. B 2010, 114, 4802–4810.
20 Liras, M.; Pintado-Sierra, M.; Amat-Guerri, F.; Sastre, R.
J. Mater. Chem. 2011, 21, 12803–12811.
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22 Araki, H.; Naka, K. Macromolecules 2011, 44, 6039–6045.
23 Araki, H.; Naka, K. Polym. J. 2011, 44, 340–346.
24 Feher, F. J.; Budzichowski, T. A. J. Organomet. Chem. 1989,
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12
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