Corner- and Side-Opened Cage Silsesquioxanes: Structural Effects on the Materials Properties

Article abstract of DOI:10.1002/ejic.201901182

Open-cage silsesquioxane, in which traditional closed-cage silsesquioxane is partially hydrolyzed, is a promising class of building blocks for constructing organic-inorganic hybrids. It has advantages of high thermal stability, low crystallinity, transparency, designability, etc. Although the structural effects of closed-cage silsesquioxanes have been elucidated in detail so far, those of open-cages have never been studied. Herein, we synthesized corner- and side-opened cage silsesquioxanes having carbazole units at the open moieties. The former was amorphous in the solid state and polymer matrix, while the latter formed crystalline structures. These different packing structures caused significant difference in the performance as an emission layer of organic light emitting device.

Full text of DOI:10.1002/ejic.201901182

A Journal of
Accepted Article
Title: Corner- and Side-Opened Cage Silsesquioxanes: Structural
Effects on the Materials Properties
Authors: Hiroaki Imoto, Yukiho Ueda, Yuri Sato, Masashi Nakamura,
Koji Mitamura, Seiji Watase, and Kensuke Naka
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To be cited as: Eur. J. Inorg. Chem. 10.1002/ejic.201901182
Link to VoR: http://dx.doi.org/10.1002/ejic.201901182

10.1002/ejic.201901182
European Journal of Inorganic Chemistry
FULL PAPER
Corner- and Side-Opened Cage Silsesquioxanes: Structural
Effects on the Materials Properties
Hiroaki Imoto,[a,b] Yukiho Ueda,[a] Yuri Sato,[a] Masashi Nakamura,[c] Koji Mitamura,[c] Seiji Watase,[c]
and Kensuke Naka*[a,b]
Abstract: Open-cage silsesquioxane, in which traditional closed-
cage silsesquioxane is partially hydrolyzed, is a promising class of
building blocks for constructing organic-inorganic hybrid. It has
advantages in high thermal stability, low crystallinity, transparency,
designability, etc. Although the structural effects of closed-cage
silsesquioxanes have been elucidated in detail so far, those of open-
cages have never been studied. Herein, we synthesized corner- and
side-opened cage silsesquioxanes having carbazole units at the
open moieties. The former was amorphous in the solid state and
polymer matrix, while the latter formed crystalline structures. These
different packing structures caused significant difference in the
performance as an emission layer of organic light emitting device.
Materials based on IC-POSS are recently emerging research
subjects of interest. Corner- and side-opened IC-POSSs are
commercially available. Conventionally, corner-opened IC-POSS
has been recognized as a precursor for mono-functionalized
CC-POSS.[4a,7,10] On the other hand, the silanol groups of IC-
POSS are excellent tools to three-dimensionally link functional
units. We and other researchers reported IC-POSS materials
used to the main-chain polymers,[11] cross-linking agents,[12]
nano-fillers,[13] amphiphilic molecules,[14] etc. It is notable that
dispersibility of IC-POSS is higher than the corresponding CC-
POSS, while they have similar thermal stabilities.[14a]
Introduction
Silsesquioxanes ((RSiO1.5)n) are promising building blocks for
constructing organic-inorganic hybrid materials because the
organic substituents (R) are incorporated to the siloxane
networks.[1] In general, the structures of silsesquioxanes are
classified into three types, i.e., random, ladder,[2] and cage[3]
structures. Cage silsesquioxanes, denoted as polyhedral
oligomeric silsesquioxanes (POSS), are particularly suitable for
precisely designed materials; structural control of random
silsesquioxanes is difficult, and synthesis of ladder
silsesquioxanes requires troublesome procedures. POSSs are
further classified into two types such as closed and open types,
called here CC-POSS (completely condensed POSS, Chart 1a)
and IC-POSS (incompletely condensed POSS, Chart 1b),[4]
respectively. CC-POSS has been traditionally utilized for
reinforcement of organic materials; main-chain,[5,6] side-chain,[7]
cross-linking agents,[8] and nano-fillers.[9] In general,
incorporation of CC-POSS into polymers can improve
mechanical properties and thermal stability.
Chart 1. Chemical structures of (a) CC- and (b) IC-POSSs.
Here we compare the dispersibility and thermal stability of CC-
POSS and IC-POSS. Among CC-POSS structures, octa-, deca-,
and dodecameric silsesquioxanes (T8, T10, and T12, respectively)
were also compared in various perspectives: crystallinity,
porosity, photophysical properties, etc.[15] It is evident that a
cage structures of IC-POSS are crucial to the resulting materials
properties.[16] Nevertheless, the structural effects of the open-
cage core have never been studied between IC-POSS
derivatives such as corner- and side-opened IC-POSSs. For this
end, it is rational that introduction of emissive units into the open
moieties is an effective strategy because the effects of the
structural difference can be evaluated through the observation of
the photophysical properties. In this work, we thus synthesized
carbazole-substituted corner- and side-opened IC-POSSs (2a
and 2b, respectively), and elucidated relationships between their
structures and materials properties.
[a]
Dr. H. Imoto, Y. Ueda, Y. Sato, Prof. Dr. K. Naka
Faculty of Molecular Chemistry and Engineering, Graduate School
of Science and Technology
Kyoto Institute of Technology
Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
E-mail: kenaka@kit.ac.jp
Homepage: http://www.cis.kit.ac.jp/~kenaka/index_eng.html
Materials Innovation Lab, Kyoto Institute of Technology,
Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
Dr. M. Nakamura, Dr. K. Mitamura, Dr. S. Watase
Osaka Research Institute of Industrial Science and Technology,
Morinomiya Center
[b]
[c]
1-6-50 Morinomiya, Joto-ku, Osaka 536-8553,Japan
Supporting information for this article is given via a link at the end of
the document.
This article is protected by copyright. All rights reserved.

10.1002/ejic.201901182
European Journal of Inorganic Chemistry
FULL PAPER
Results and Discussion
Table 1. Thermal properties of 1 and 3.
TGA
DSC
The syntheses of 2a and 2b are shown in Scheme 1. Corner-
and side-opened IC-POSSs having dimethylsilyl capping groups
(1a[14a] and 1b,[17] respectively) were prepared from commercially
available trisilanol- and disilanol-IC-POSSs in using to our
Td5 [°C][a]
Td10 [°C][a]
Tm [°C][b]
-18[c]
66
1a
1b
3
200
226
208
213
239
218
published procedure.[14a] Hydrosilylation of
vinylcarbazole was carried out in the presence of Karstedt's
catalyst ([Pt(dvs)], dvs 1,3-divinyl-1,1,3,3-
1
with 9-
=
135
tetramethyldisiloxane). The products were purified using a
preparative HPLC using chloroform (CHCl3) as the eluent. The
residual metal species were removed using an amine-modified
metal scavenger. The chemical structures of 2 were determined
by NMR spectroscopy and MALDI-TOFMS, and the purities
were confirmed by size exclusion chromatography (SEC).
[a] The temperatures at which the samples lost 5 and 10 wt% from the
original mass (Td5 and Td10, respectively). [b] Melting point. [c] Cited
from reference 14a.
The optical properties of 2 were investigated as shown in
Figure 1 and Table S1. The UV-vis absorption (Figure 1a) and
photoluminescence (PL) spectra (Figure 1b) of 2 and 9-
ethylcarbazole were measured in THF solutions ([carbazole unit]
= 5.0 × 10-5 M). The spectra of 2 and 9-ethylcarbazole were
quite similar, meaning that the carbazole units on the IC-POSSs
have negligible interactions in the ground and excited states. We
further examined donor-acceptor interactions between the
carbazole moieties and m-dinitrobenzene, but no significant
differences were observed (for detail, see Figure S12). In the
case of the solid state (Figure 1c), the PL spectra of 2 were also
quite similar, though that of 9-ethylcarbazole showed red-shifted
spectra by 39 nm (2a) and 40 nm (2b); the carbazole units of 2
and 9-ethylcarbazole were partially and totally eclipsed,
respectively.[19] These results indicate that there are no structural
effects of the open-cages on the photophysical properties in
solution and solid states.
Scheme 1. Syntheses of carbazole-substituted (a) corner- and (b) side-
opened IC-POSSs, and chemical structure of 3.
The thermal properties of IC-POSSs 1 and heptaisobutyl-CC-
POSS 3 were examined by thermogravimetric analysis (TGA)
and differential scanning calorimetry (DSC).[18] The temperatures
at which the samples lost 5 and 10 wt% from the original mass
(Td5s and Td10s, respectively), and melting points (Tms) are
summarized in Table 1 and Figure S11. The Td5s and Td10s of 1
were comparable to those of 3, meaning that thermal stability
was not affected by opened the POSS core. On the other hand,
the Tms of 1 were significantly lower than that of 3 due to the
open-cage structures; in particular, 1a is liquid at room
temperature.[14a] This is because the crystallinity of POSS was
lowered by the reduced symmetry of core structures (vide infra).
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10.1002/ejic.201901182
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FULL PAPER
Figure 1. (a) UV-vis and (b) PL spectra of 2 and 9-ethylcarbazole in THF
solutions ([carbazole unit] = 5.0 × 10-5 M). (c) PL spectra of 2 and 9-
ethylcarbazole in the solid states.
due to the mobility and flexibility of carbazole groups in the
hybrid.
During the investigation on the solid state emission properties,
we found that the appearances of 2 in their solid states were
different. That is, films of 2a were transparent (Figure 2a),
whereas 2b formed a turbid film (Figure 2b). We thus conducted
scanning electron microscope (SEM) studies for the films of 2
(Figure 2c and 2d). The film of 2a is homogeneous, while
aggregates of sub-micrometer to micrometer order were
observed for 2b. Powder X-ray diffraction (XRD) patterns
indicate that 2b has much higher crystallinity than 2a. This
corresponds to DSC measurements shown in Table 1; side-
opened IC-POSS 1b is crystalline at room temperature while
corner-opened IC-POSS 1a is a liquid.
Figure 3. (a) Current density and luminance curves versus driving voltage and
(b) photographs of OLEDs using PPSQ- composites with 2a and 2b as
emission centers.
XRD measurements of the PPSQ composite films were
conducted to understand the difference in morphology in the
devices between 2a and 2b (Figure S10). The XRD of the 2a-
PPSQ film shows it was amorphous, whereas that of 2b-PPSQ
film revealed crystals of 2b. The grain boundaries of 2b might
inhibit charge transfer in the composite film. Raman
spectroscopy is a useful technique for comparing crystallinity,
and gives a sharp peak with a narrow half width at high
crystallinity. Therefore, to compare the difference in crystallinity
of the IC-POSS cores, Raman measurements were performed in
solution and in the solid state. A peak attributed to the stretching
mode of the biphenyl skeleton derived from the carbazole group
of interest and was observed near 1630 cm-1. Figure S14a
shows those peaks derived from 2a and 2b in THF solutions.
The full width at half maxima (FWHM) of the peaks of 2a and 2b
are similar. Thus the carbazole groups of 2a and 2b have similar
environments in solution. On the other hand, the FWHM of the
peak due to 2a in the solid state was larger than that of 2b
(Figure S14b). The periodicity of the carbazole group of 2a in the
solid state is more disordered that that of 2b, because of the
lower crystallinity due to a corner-opened IC-POSS core. This
observation is consistent with the X-ray diffraction
measurements.
Finally, the symmetrical difference between corner- and side-
opened IC-POSSs and CC-POSS was evaluated based on the
structures which were optimized by density functional theory
(DFT) calculations (Figure 4).[21] The structures were simplified
for the calculation cost; the isobutyl and carbazolylethyl groups
were replaced by methyl groups; the virtual molecules were
defined as 2a’ (corner-opened IC-POSS), 2b’ (side-opened IC-
POSS), and 3’ (CC-POSS). The calculations were performed at
the B3LYP/6-31G(d) level of theory with the Gaussian 09.[22] The
centroids of the silicon atoms that form the cage structures were
calculated by the Cartesian coordinates. The symmetry of the
cages was evaluated by the variance () of the distance
Figure 2. (a, b) Photographs and (c, d) SEM images the films of 2, which were
fabricated by drop-casting from CHCl3 solutions (75 g/L). (e) Powder XRD
patterns of 2.
This result motivated us to investigate the electronic
properties that might depend on the morphologies of hole-
transporting carbazole groups in each IC-POSS.[20] Since the
performance of light-emitting devices (OLEDs) depend on the
luminescent and electronic properties of the light emitting layer,
we fabricated devices using IC-POSSs 2 and evaluated their
performance. In order to apply 2 as emission centers to OLEDs,
they were made into thin films by hybridizing with
poly(phenylsilsesquioxane) (PPSQ). The ratio of [carbazole
group] to [phenyl group] was 2 to 3 for both the hybrid films.
Device configurations were Al/TAZ/2-PPSQ/PEDOT/ITO. Both
devices
were
successfully
fabricated
and
showed
electroluminescence. In these devices, the carbazole group can
play a role as a recombination site for holes and electrons as
well as an emission center. Comparing to two devices, the
maximum current density and the maximum luminance of the
device containing 2a was approximately twice those of a device
containing 2b (Figures 3 and S13). This result strongly suggests
that the difference in crystallinity greatly affects device
performance. In particular, low crystallinity of corner-opened IC-
POSS core leads to good device performance, which may be
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10.1002/ejic.201901182
European Journal of Inorganic Chemistry
FULL PAPER
between the centroid and each silicon atom. In the case of 3’, 
was approximately 0 due to the highly symmetrical cubic
structure. On the other hand, the corner- and side-opened cages
possessed relatively large  values, and the  value of 2a’ ( =
0.446) was significantly larger than that of 2b’ ( = 0.344). This
means that the corner-opened structure possesses lower
symmetry than the side-opened structure, well corresponding to
the experimental results that show the lower crystallinity of 2a.
which the present study elucidated has opened new avenue to
development of silsesquioxane materials.
Experimental Section
1. Materials
Tetrahydrofuran (THF), chloroform (CHCl3), triethylamine (NEt3), and
methanol (MeOH) were purchased from Nacalai Tesque (Kyoto, Japan).
Toluene, n-hexane, magnesium sulfate anhydrous (MgSO4), and distilled
water were purchased from Fujifilm Wako Pure Chemical Industry
(Osaka, Japan). Chlorodimethylsilane, 9-vinylcarbazole, 9-ethylcarbazole,
and m-dinitrobenzene were purchased from Tokyo Chemical Industry
(Tokyo, Japan). Xylene solution (0.1 M) of platinum(0)-1,3-divinyl-1,1,3,3-
tetramethyldisiloxane (Pt(dvs)) was purchased from Sigma-Aldrich
(Hattiesburg, Mississippi, US). Heptaisobutyl trisilanol POSS and
octaisobutyl disilanol POSS were purchased from Hybrid Plastics Inc
(Hattiesburg, Mississippi, US). Metal scavenger, SiliaMetS(R) Triamine
(Particle size: 40ꢀ-ꢀ63 µm, Pore diameter: 60 Å, Particle shape: Irregular
Silica Gel) was purchased from SiliCycle, Inc (Quebec City, Québec,
Canada). Heptaisobutyl POSS (3) was prepared according to the
literature procedure.[14a]
2. Method
1H (400MHz), 13C (100MHz), and 29Si (80MHz) nuclear magnetic
resonance (NMR) spectra were recorded on
a Bruker DPX-400
spectrometer (Bruker Biospin GmbH, Rheinstetten, Germany) in CDCl3
using Me4Si as an internal standard. The following abbreviations are
used: t, triplet; q, quartet; quint, quintet; sext, sextet; sep, septet; m,
multiplet. Molecular weights were determined by size exclusion
chromatography (SEC) of LC-6AD (Shimadzu, Kyoto, Japan) with a
Shodex KF-803L (Showa Denko, Tokyo, Japan) column and a refractive
index detecotr RID-20A (Shimadzu, Kyoto, Japan). Preparative high-
performance liquid chromatography (HPLC) for purification was
performed on LC-6AD (Shimadzu, Kyoto, Japan) with a KF-2001 using
chloroform as an eluent. Matrix assisted laser desorption ionization time-
of-flight mass spectrometry (MALDI-TOF-MS) was recorded on a Bruker
Autoflex II instrument (Bruker Daltonics, Billerica, MA, USA): trans-2-[3-
Figure 4. (Left) Optimized structures of 2a’, 2b’, and 3’ (yellow: Si, red: O,
grey: C, white: H). (Right) Part of cage core structures and distances (Å)
between centroid (blue dot) and silicon atoms. Average () and variance () of
the distances are shown.
(4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile
(DCTB)
matrix (20 mg/mL in CHCl3) and sodium trifluoroacetate cationizing
agents (1 mg/mL in THF). TGA and DSC measurements were performed
by Shimadzu DTG-60 and DSC-60 Plus (Shimadzu, Kyoto, Japan),
respectively, under nitrogen atmosphere at a heating rate of 10 °C/min.
Conclusions
UV-vis absorption spectra were recorded on
a
JASCO
IC-POSS is an excellent tool to design organic-inorganic
hybrid molecules because the silanol groups can be used for
incorporation of the functional units into the stable inorganic core.
In the present work, carbazole-substituted corner- and side-
opened IC-POSSs 2 were synthesized to demonstrate their
differences in the structures and materials properties. The
structures of IC-POSS cores made negligible differences in the
photophysical properties in solutions and the solid states,
considering the UV-vis and PL spectra. On the other hand, the
molecular packings in the solid states were significantly different;
2a was amorphous, while 2b formed the crystalline structure.
The high dispersibility of 2a realized more efficient emission in
the OLED, whereas the crystallization of 2b inhibited the charge
transport. This is the first study on the structural effects of the
IC-POSSs on photophysical properties. The molecular design
spectrophotometer V-670 KNN (JASCO, Tokyo, Japan). Emission and
excitation spectra were obtained on an FP-8500 (JASCO), and absolute
PL quantum yields (Φ) were determined using a JASCO ILFC-847S; the
quantum yield of quinine sulfate reference was 0.52, which is in
agreement with the literature value.[23] X-ray diffractometry (XRD) studies
were performed on a Rigaku Smartlab X-ray diffractometer with Cu Kα
radiation (λ = 1.5406 Å) in the 2θ/θ mode at room temperature. The 2θ
scan data were collected at 0.01° intervals and the scan speed was 10˚
(2θ) / min. The surface of the films was observed using a VE-8800
scanning electron microscope (SEM) (KEYENCE, Osaka, Japan).
Raman spectra were taken using a HORIBA Raman spectrometer
LabRAM HR Evolution (Horiba, Kyoto, Japan). The laser excitation
wavelength used in these studies was 532 nm and the output was 15
mW in the solid state or 30 mW in solution, respectively. The
wavenumber resolution was 0.4 to 0.5 cm-1.
3. Synthetic procedure and characterization data
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10.1002/ejic.201901182
European Journal of Inorganic Chemistry
FULL PAPER
Tris(dimethylsiloxy)heptaisobutyl IC-POSS (1a).[14a] A THF solution
(30 mL) of heptaisobutyl trisilanol POSS (2.0 g, 2.53 mmol) and Et3N
(2.45 mL, 17.7 mmol) was cooled to 0 °C under N2 atmosphere, and
chlorodimethylsilane (1.23 mL, 11.4 mmol) was added dropwise. After
stirring at 0 °C for 1 h, the reaction mixture was warmed to room
temperature for 3h, and the reaction was quenched by addition of
distilled water. The volatiles were removed in vacuo, and the residue was
dissolved in n-hexane. The solution was washed with distilled water, and
the organic layer was dried over MgSO4. The solvent was removed in
vacuo, and the residue was subjected to reprecipitaion from the CHCl3
solution to methanol to obtain 1a (2.15 g, 2.22 mmol, 87%) as white
solids. 1H-NMR (CDCl3, 400 MHz) δ 4.74 (sep, J = 2.86 Hz, 3H), 1.89-
1.79 (m, 7H), 0.96 (quint, J = 3.56 Hz, 42H), 0.56(t, J = 6.47 Hz, 14H),
0.22 (q, J = 3.33 Hz, 18H) ppm; 13C-NMR (CDCl3, 100 MHz) δ 26.0, 25.8,
25.6, 24.6, 24.1, 24.0, 23.9, 23.6, 22.4, 0.6 ppm; 29Si-NMR (CDCl3, 80
MHz) δ -5.4, -67.1, -67.6, -68.0 ppm.
TOFMS (m/z): calculated for C64H108O13N2Si10 [M]+·: 1392.55, found
1392.56.
4. Evaluation of OLED devices
Preparation of PPSQ. To a THF solution of phenyltrimethoxysilane (0.22
g, 0.10 mmol), small amount of formic acid as a catalyst and four
equivalents of water (0.007 g, 0.40 mmol) were added.
The
condensation of the reaction mixture was carried out in a glass vessel
upon stirring at 90˚C for 1 h, and then at 120˚C for another 1 h, giving a
solid product. CHCl3 solutions (0.5 wt%) of 2a, 2b, and PPSQ were
separately prepared, and they were mixed ([carbazole group]: [phenyl
group] = 2: 3) for fabrication of the OLEDs.
Device fabrication. The OLED was fabricated on the ITO glass by the
following procedure. Firstly, the hole transporting PEDOT: PSS and
hybrid emitting layers were deposited sequentially by spin-coating. These
coatings were post-baked using hot-plate heated at 100 degree. Next,
electron transporting TAZ layer and Al electrode were deposited
sequentially under high vacuum environment (< 3.0 × 10–3 Pa) by thermal
evaporation onto spin-coated substrates with a speed of 0.1–0.3 nm/s.
The thickness of the vacuum deposition layers were controlled by the
quartz crystal unit. The emission area of the device was 0.16 cm2 as
determined by the overlap area of the anode and the cathode. Device
current density-voltage-luminance characteristics were measured without
Bis(dimethylsiloxy)octaisobutyl IC-POSS (1b). A THF solution (30 mL)
of octaisobutyl disilanol POSS (2.0 g, 2.24 mmol) and Et3N (2.18 mL,
15.7 mmol) was cooled to
0 °C under N2 atmosphere, and
chlorodimethylsilane (0.73 mL, 6.73 mmol) was added dropwise. After
stirring at 0 °C for 1 h, the reaction mixture was warmed to room
temperature for 3h, and the reaction was quenched by addition of
distilled water. The volatiles were removed in vacuo, and the residue was
dissolved in n-hexane. The solution was washed with distilled water, and
the organic layer was dried over MgSO4. The solvent was removed in
vacuo, and the residue was subjected to reprecipitaion from the CHCl3
solution to methanol to obtain 1b (1.97 g, 1.95 mmol, 85%) as white
solids. 1H-NMR (CDCl3, 400 MHz) δ 4.73 (sep, J = 2.77 Hz, 2H), 1.90-
1.80 (m, 8H), 1.02-0.90 (m, 48H), 0.57 (sext, J = 2.07 Hz, 16H), 0.28-
0.18 (m, 12H) ppm; 13C-NMR (CDCl3, 100 MHz) δ 25.9, 25.9, 25.8, 25.7,
24.6, 24.0, 23.9, 23.8, 23.5, 22.5, 0.59 ppm; 29Si-NMR (CDCl3, 80 MHz)
δ -5.17, -65.8, -66.0, -68.1 ppm. The NMR spectral data corresponds the
literature.[17]
protective encapsulation at ambient conditions using
a computer-
controlled ADCMT 6241A DC voltage current source / monitor attached
with a Konica Minolta Chroma meter CS-100A. The EL spectra were
recorded by Hitachi F4500 fluorescence spectrophotometer.
Acknowledgments
This work was supported by JSPS KAKENHI Grant Number
JP18K19114. H. I. acknowledges Grant-in-Aid for Young
Scientists (B) (JSPS KAKENHI Grant Number JP17K14530).
We thank Prof. Tsuyoshi Kawai and Ms. Yoshiko Nishikawa of
Nara Institute of Science and Technology for measuring MALDI-
TOF-MS supported by Nanotechnology Platform.
Tris((carbazolylethyl)dimethylsiloxy)heptaisobutyl IC-POSS (2a). To
a
toluene solution (7.0 mL) of 1a (0.70 g, 0.72 mmol) and 9-
vinylcarbazole (0.63 g, 3.26 mmol) was added a xylene solution of
Pt(dvs) (0.1 M, 29 L) under N2 atmosphere. After stirring at 80 °C for 6 h,
the volatiles were removed in vacuo. The residue was subjected to
preparative HPLC, and the residual metal species were adsorbed to
metal scavenger, SiliaMetS(R) Triamine. The solvents were removed in
vacuo to obtain 2a (0.85 g, 0.55 mmol, 76%) as white viscose solids. 1H-
NMR (CDCl3, 400 MHz) δ 8.11-7.17 (m, 24H), 4.40-4.28 (m, 6H), 1.98-
1.87 (m, 7H), 1.18-1.10 (m, 6H), 1.07-0.96 (m, 42H), 0.66 (sext, J = 6.65
Hz, 14H), 0.27-0.09 (m, 18H) ppm; 13C-NMR (CDCl3, 100 MHz) δ 139.8,
125.5, 123.0, 120.4, 118.7, 108.5, 38.2, 26.1, 25.9, 25.7, 25.1, 24.3, 24.1,
23.9, 23.8, 22.4, 18.3, 0.53 ppm; 29Si-NMR (CDCl3, 80 MHz) δ 7.49, -
67.0, -67.0, -67.1 ppm. MALDI-TOFMS (m/z): calculated for
C76H117O12N3Si10 [M]+·: 1543.63, found 1543.63.
Keywords: Luminescence • Silicon • Cage compounds • Density
functional calculations • X-ray diffraction
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Bis((carbazolylethyl)dimethylsiloxy)octaisobutyl IC-POSS (2b). To a
toluene solution (2.0 mL) of 1b (0.20 g, 0.20 mmol) and 9-vinylcarbazole
(0.12 g, 0.60 mmol) was added a xylene solution of Pt(dvs) (0.1 M, 14
L) under N2 atmosphere. After stirring at 80 °C for 6 h, the volatiles were
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(0.20 g, 0.15 mmol, 74%) as white solids. 1H-NMR (CDCl3, 400 MHz) δ
8.03-7.09 (m, 16H), 4.36-4.25 (m, 4H), 1.89-1.72 (m, 8H), 1.11-0.99 (m,
4H), 0.95-0.81 (m, 48H), 0.60-0.44 (m, 16H), 0.22-0.04 (m, 12H) ppm;
13C-NMR (CDCl3, 100 MHz) δ 139.8, 125.5, 123.0, 120.4, 118.6, 108.5,
38.2, 26.1, 25.9, 25.8, 25.8, 25.1, 24.2, 24.0, 23.8, 23.6, 22.5, 18.4, 0.52
ppm; 29Si-NMR (CDCl3, 80 MHz) δ 7.62, -65.3, -65.7, -67.4 ppm. MALDI-
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10.1002/ejic.201901182
European Journal of Inorganic Chemistry
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Entry for the Table of Contents
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Open-cage silsesquioxanes
H. Imoto, Y. Ueda, Y. Sato, M.
Nakamura, K. Mitamura, S. Watase, K.
Naka*
Page No. – Page No.
Two well-known open-cage silsesquioxanes, corner- and side-opened types, were
compered from viewpoints of structures and materials properties. The difference in
crystallinity drastically affected the OLED performance when carbazole groups were
incorporated.
Corner- and Side-Opened Cage
Silsesquioxanes: Structural Effects
on the Materials Properties
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