High-yield synthesis of amido-functionalized polyoctahedral oligomeric silsesquioxanes by using acyl chlorides

Article abstract of DOI:10.1002/chem.201404153

Homosubstituted amido-functionalized polyoctahedral oligomeric silsesquioxanes (POSS) have been synthesized by using acyl chlorides in high yields (ca. 95%). The method proved to be superior over "conventional" syntheses applying carboxylic acids or acid

Full text of DOI:10.1002/chem.201404153

DOI: 10.1002/chem.201404153
Full Paper
&
Siloxane Nanoparticles
High-Yield Synthesis of Amido-Functionalized Polyoctahedral
Oligomeric Silsesquioxanes by Using Acyl Chlorides
Mateusz Janeta, Łukasz John,* Jolanta Ejfler, and Sławomir Szafert[a]
1
Abstract: Homosubstituted amido-functionalized polyocta-
hedral oligomeric silsesquioxanes (POSS) have been synthe-
sized by using acyl chlorides in high yields (ca. 95%). The
method proved to be superior over “conventional” syntheses
applying carboxylic acids or acid anhydrides, which are
much less efficient (ca. 60% yield). A palette of aryl and alkyl
groups has been used as side-chains. The structures of the
resulting amide-POSS are supported by multinuclear H, 13C,
29Si NMR and FTIR spectroscopy and their full conversion
into octasubstituted derivatives was confirmed using mass
spectrometry. We also demonstrate that the functionalized
silsesquioxanes with bulky organic side-chains attached to
cubic siloxane core form spherical-like, well-separated nano-
particles with a size of approximately 5 nm.
a unique combination of conjugation and porosity.[7] Fluorinat-
ed POSS (F-POSS) also constitute an interesting class of com-
pounds for, among others, the construction of superamphi-
phobic and flexible macroporous monoliths,[8] self-healing, su-
perhydrophobic, and superoleophobic surfaces,[9,10] or transpar-
ent, flexible and superomniphobic surfaces.[11] Furthermore,
amide-derivatives of octa(3-aminopropyl)silsesquioxanes (OAS)
play a crucial role in the field of biomaterials.[12,13]
Introduction
Polyoctahedral oligomeric silsesquioxanes (POSS) constitute
a group of organosilicon compounds with the basic structure
of general formula (RSiO3/2)8.[1] Their attractiveness derives from
the fact that they can contain numerous functional groups as
side-chains, spawning various possibilities to attach organic
fragments. These groups—the so-called organic shell—can be
varied from alkyl to alkylene or arylene. Thus, such molecules
can fundamentally be regarded as truly inorganic core/shell
structures that are able to bind organic moieties, polymers,
and natural biomaterials. Moreover, the presence of the three
SiꢀO bonds together imparts superior thermal, mechanical,
and chemical stability, which makes these compounds ex-
tremely interesting from an industrial point of view.[2]
Within this class of cage-like organosilicons, considerable at-
tention is focused on aminopropyl-functionalized POSS (OAS-
POSS) prepared by a sol-gel process based on the hydrolytic
condensation of 3-aminopropyltrialkoxysilane, for example, 3-
aminopropyltriethoxysilane (APTES) or aminopropyltrimethoxy-
silane (APTMS). However, the synthesis of cage-like octa(3-ami-
nopropyl)silsesquioxane is cumbersome and gives relatively
low yields (ca. 30%) and requires a long reaction time (up to 6
weeks) when conducted in a mixture of MeOH/HCl at 258C.[14]
Moreover, the products usually contain contaminations of
other polyhedral silsesquioxanes such as (RSiO3/2)n (n ¼ 8) or
open cage-like structures.[15–17]
Many interesting examples that illustrate these remarkable
properties have already been described.[3] For example, porous
hybrid materials based on “click” chemistry or polymerization
methodology can be obtained from vinyl-POSS-derivatives that
constitute building blocks for 3D networks.[4,5] Schwab et al.
described a synthetic approach to easy-to-scale-up modifica-
tion of POSS cages that allows for their incorporation into ther-
moplastic resins resulting in increased oxygen permeability, re-
duced flammability, and mechanical properties effectively
closer to relative conventional organic systems.[6] Copper and
co-workers reported on soluble ramified aryl-like conjugated
microporous polymers (CMP) based on POSS architecture that
open a new range of applications of CMPs that exploit
Some modifications have been reported that have led to
better synthetic efficacy for OAS-POSS preparation; for exam-
ple, the use of tetraethyl ammonium hydroxide Et4NOH as cat-
alyst (yields <70% after 24 h).[18] Some improvement has also
been achieved by optimization of the standard reaction condi-
tions (ca. 30%, 5–10 days).[19] Kaneko and co-workers devel-
oped another valuable approach to the synthesis of such sys-
tems.[20] They investigated the hydrolytic condensation of
APTMS by using a number of different acid catalysts. The most
effective approach proved to involve the use of trifluorometha-
nesulfonic acid. OAS-POSS-CF3SO3 was prepared after 5–6 h in
approximately 90% overall yield. However, the authors ob-
served the presence of decasubstituted polyhedral silsesquiox-
ane as a minor by-product.[21] Nevertheless, such a novel strat-
egy opened a new way for the preparation of a range of so-
phisticated OAS-POSS-based derivatives.
[a] M. Janeta, Dr. Ł. John, Dr. J. Ejfler, Dr. S. Szafert
Faculty of Chemistry, University of Wrocław
14 F. Joliot-Curie, 50-383 Wrocław (Poland)
Fax: (+48)71-328-23-48
E-mail: lukasz.john@chem.uni.wroc.pl
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201404153.
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Laine et al. investigated a valid strategy for the synthesis of
imide-derivatives of OAS-POSS starting from acyl anhydrides.[19]
In this paper, we present a new synthetic approach that allows
a high-yield synthesis of OAS-POSS from ionic precursors and
describe its modification to access various amide-derivatives
starting from acyl chlorides. We have also been able to obtain
nanoparticles of amido-functionalized OAS-POSS-like species
containing aryl and alkyl side-chains (Figure 1), which were
synthesized in high yield and purity while avoiding the forma-
tion of other (n ¼ 8) polyhedral silsesquioxanes or polymeric/
oligomeric compounds.
Scheme 1. Synthesis of [OAS-POSS-NH3]X.
metrical peak) for 1, 2, and 3, respectively, and confirmed the
presence of only one type of Si nucleus. The characteristic
peaks (d=8.23, 2.79, 1.74, 0.75 ppm for 1, d=7.57, 2.75, 1.56,
0.66 ppm for 2, and d=7.97, 2.79, 1.61, 0.62 ppm for 3) in the
1H NMR spectra indicated the formation of cage-like structures
+
with terminal -PrNH3 moieties (Table 1). In the FTIR spectra of
1–3, the Si-O-Si stretching gave strong absorptions around
1116, 1136, and 1132 cmꢀ1 for 1, 2, and 3, respectively. Siloxane
absorption, compared those obtained with conventional
hybrid materials obtained by sol-gel method, were much nar-
rower in 1–3, supporting a high symmetry of the resulting
products.
Figure 1. Alkyl, aryl, and fluorinated side-chains utilized in an amido-func-
tionalized OAS-POSS.
Crystalline compounds 1 and 2 were selected as the most
promising materials for subsequent investigations. Compound
3 was excluded because it continued to form a highly hygro-
scopic glassy product, which appeared to be more difficult to
hand in further studies. The crystalline nature of 1–3 and other
compounds was confirmed by using powder XRD analysis
(Figure 2 and the Supporting Information). We also investigat-
ed the compounds by TEM analysis combined with selected
area electron diffraction (SAED) analysis (Figure 3). Particles
were found to form in the nanometer size range (5–10 nm).
TEM images clearly showed that 3 constituted a shapeless
product.
Results and Discussion
Looking for a stable cage scaffold for further preparation of
octa-amido-functionalized POSS derivatives, in the first ap-
proach we obtained three OAS-POSS-based salts, [OAS-POSS-
NH3]Cl (1), [OAS-POSS-NH3]CF3SO3 (2), and [OAS-POSS-
NH3]CF3COO (3), as shown in Scheme 1.
Compounds 1–3 were obtained in a one-step hydrolytic
condensation by using commercially available (3-aminopropyl)-
triethoxysilane (APTES) and an appropriate amount (relative to
APTES) of hydrochloric HCl (3.6 equiv), trifluoromethanesulfon-
ic CF3SO3H (1.5 equiv), or trifluoroacetic CF3COOH (1.5 equiv)
acid. Their structures were unambiguously confirmed with
high-resolution mass spectrometry and multinuclear (1H, 13C,
29Si) NMR spectroscopy (see Experimental Section and the Sup-
porting Information). The chemical shifts of 29Si NMR signals
were within the expected region for alkyl-substituted cubic
POSS[3] at d=ꢀ66.52, ꢀ66.53, and ꢀ66.65 ppm (single, sym-
Ionic compounds 1 and 2 were next utilized to obtain cube-
like neutral aminopropylsilsesquioxane 4 (OAS-POSS). From
a synthetic perspective, it is much better to generate 4 in
a one-pot transformation from crystalline, air-stable com-
pounds 1 or 2 directly before the synthesis of the target OAS-
POSS derivatives because pure, liquid 4 is constantly evolving
in solution. It is worth noting here that the synthesis of 4 and
its derivatives requires strictly anhydrous conditions, otherwise
Table 1. NMR Data for 1-4.
Compound
1H NMR (NH3+), (CH2NH3+), (-CH2-), (SiCH2)
13C NMR (CH2NH3+), (-CH2-), (SiCH2)
29Si NMR[a]
1
2
3
4
8.23, 2.79, 1.74, 0.75[a]
7.57, 2.75, 1.56, 0.66[a]
8.04, 2.80,1.62, 0.62[a]
2.60, 1.54, 0.63[b]
41.7, 20.6, 8.7[c]
ꢀ66.52
ꢀ66.53
ꢀ66.65
ꢀ66.53
122.5 (CF3SO3ꢀ), 44.4, 23.3, 11.3[c]
159.5 (CF3COOꢀ), 117.4 (CF3COOꢀ), 41.4, 21.0, 8.6[a]
44.4, 26.6, 9.8[a]
[a] Measured in DMSO. [b] Measured in CD3OD. [c] Measured in D2O.
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was transformed into a stable salt through the addition of
a methanol solution of hydrochloric acid (0.5m). In the proton
NMR spectrum of the resulting white precipitate of 5, a broad
signal at d=3.64 ppm for the silanol group was observed; in
the NOESY spectrum, this signal gave an NOE cross-peak with
+
the -NH3 signal (Figure S19). An open cage-like structure was
proposed based on the 29Si NMR spectra (Figure 4).
Figure 2. Powder XRD patterns for 1–3 and 5–10.
Figure 4. 29Si NMR (59.6 MHz, [D6]DMSO, 208C) spectra of 1, 4, and 5.
For OAS-POSS 4 and its salt 1, only one signal assigned to
the Si nucleus at approximately d=ꢀ66.5 ppm was observed.
In the case of open cage-like compound 5, two signals from
silicon nuclei were localized at d=ꢀ65.90 and ꢀ66.65 ppm.
The first signal derives from the silicon atom with three Si-O-Si
moieties, and the second from signals with two Si-O-Si and
one Si-OH groups (see Scheme 2). Both signals possess similar
intensity, because they correspond to four silicon atoms each.
Moreover, in the 13C NMR spectra of 5, the carbon atoms di-
rectly bound to the silicon (signals at d=9.0 and 8.7 ppm)
have a different chemical shift compared with those from the
cage-like structures (one signal at d=9.8 ppm for 4). Further-
more, the presence of silanol groups, which are characteristic
for open cage-like structure, can be easily identified by using
infrared spectroscopy. The n(Si-OH) vibration was observed at
990 cmꢀ1. Furthermore, the structure of 5 was additionally sup-
ported by mass spectrometry (see the Supporting Information).
Based on the previous reports, the mechanism of opening of
cage-like compound 4 involves attack by an amine nitrogen
on the silicon atom, which further reacts with water to pro-
duce a silanol moiety.[22] It should be emphasized that the core
opening is caused not by the presence of a hydroxyl group
but by an aliphatic amine. This conclusion is supported by the
fact that during further synthesis of the amide-derivatives, the
final product was washed with an aqueous solution of NaHCO3
and if the amine group was blocked such an opening did not
occur.
Figure 3. TEM Images of 1 (a, b), 2 (c, d), and 3 (e), and selected area diffrac-
tion patterns (Insets in b and d). Scale bars: a) 50 nm; b) 5 nm; c) 20 nm; d)
5 nm; e) 2 mm.
the formation of open cage-like 5 can be postulated as shown
in Scheme 2.
As mentioned above, during the synthesis of 4 from 1 or 2
under hydrous conditions, we noticed decomposition of the
cage-like structure. To investigate this effect, 5% aqueous solu-
tion of sodium hydrocarbonate was added to 1 in a controlled
way. To inhibit degradation of 5 in solution, this compound
The presence of -PrNH2 side-chains of neutral 4 was con-
firmed by using H NMR spectroscopic analysis. Signals of iden-
Scheme 2. The formation of cage-like OAS-POSS and open cage-like struc-
tures depending on reaction conditions: a) anhydrous conditions; b) hy-
drous conditions.
1
tical integration localized at d=2.60, 1.54, and 0.63 ppm were
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assigned
to
-CH2NH2,
-SiCH2CH2CH2NH2, and -SiCH2-
fragments, respectively. Given
that these chemical shifts would
be similar for all the “amino-
propyl” compounds, in Table 1
we show these data for other
species.
The 29Si NMR spectrum exhib-
ited only one symmetrical peak,
as expected for a cubic struc-
ture, which strongly indicates
Scheme 4. Synthesis of 7 by reduction of 6 with hydrogen.
the presence of only one type of
silicon atoms in the molecule of
4, comprised of three siloxane
-Si-O-Si- moieties. No silanol groups were observed. The mass
spectrum {HRMS (ESI+, TOF/CH3OH): m/z (%): 881.2916 (45)
[M+H]+ (calcd 881.2871), 441.1635 (100) [M+2H]2+ (calcd
441.1469), 294.4442 (20) [M+3H]3+ (calcd 294.4339)} confirmed
the formation of a closed frame structure composed of eight
silicon atoms possessing terminal aminopropyl side-chains.
In the next step, homo-octafunctionalized 1 and 2 were
used for the preparation of a diverse set of hybrid materials.
This demonstrates that 1 and 2 constitute attractive scaffold
platforms for the controlled synthesis of well-defined amido-
functionalized homo-polyoctasilsesquioxanes. First, to modify
1 and 2, we used benzoyl chloride and its 4-nitro- and 4-
fluoro-derivatives as well as hexanoyl chloride, as presented in
Scheme 3. Next, the resulting 4-nitrobenzoyloamide-POSS was
utilized to prepare 4-aminobenzoyloamide-POSS as shown in
Scheme 4. The use of acyl chlorides led to higher yields (ca.
90%) compared with those observed in the “conventional” re-
actions through the use of carboxylic acids or acid anhydrides
(ca. 60%).[21]
Initially, benzoylation reactions were carried out according
to the Schotten–Baumann[23] reaction by using sodium hydrox-
ide as base. However, NaOH proved to be too strong, causing
decomposition of the polyoctasilsesquioxane core. Further-
more, application of a weaker base (an aqueous solution of
sodium hydrogencarbonate), did not work. Only the use of the
weak base triethylamine avoided destruction of the siloxane
core. An excess of triethylamine was used 1) to generate
amine 4 in situ, which further reacted with benzoyl chloride
and 2) to neutralize HCl, which was liberated from appropriate
acyl chloride, during the reaction with 1 or 2. This procedure
allowed the synthesis of various benzamido-derivatives of oc-
taaminopropylsilsesquioxanes (6, 8, and 9). During the reac-
tion, 1.1 equiv of acid chloride was used and reaction was per-
formed in N,N-dimethylformamide at 08C. Notably, in the reac-
tion with an excess of aryl acid
chloride, the presence of tertiary
amide was not observed, which
contrasts with the reactions with
alkyl amide. NMR spectra that
confirmed this phenomenon are
presented in Figure S24. The
product yields were successfully
increased by leaving the reaction
mixture in a freezer overnight.
Next, 4-amino compound 7
was obtained by reduction of
nitro-derivative 6 with hydrogen
generated in situ, as shown in
Scheme 4. Compound 7 is stable
even when NaOH was used to
remove Zn(OH)2 and neutralize
an excess of acid (use of
a strong base did not lead to de-
struction of the cubic core). This
stability was confirmed by
29Si NMR spectroscopic analysis
(Figure 5), which revealed only
Scheme 3. Syntheses of homoocta-functionalized POSS-based hybrid materials. a) 6: 4-nitrobenzoyl chloride
8.8 equiv, NEt3 18.5 equiv, DMF, 08C; b) 8: 4-fluorobenzoyl chloride 8.8 equiv, NEt3 18.5 equiv, DMF, 08C; c) 9: ben-
zoyl chloride 8.8 equiv, NEt3 18.5 equiv, DMF, 08C; d) hexanoyl chloride 16.3 equiv, NEt3 26.4 equiv, DMF, 08C.
one chemical shift at d=
ꢀ68.0 ppm.
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Figure 5. 29Si NMR (59.6 MHz, [D6]DMSO, 208C) spectrum of 7.
Figure 7. FTIR of 10 possessing a narrow absorption band assigned to Si-O-
Si stretching.
In contrast, the reaction of 1 or 2 with hexanoyl chloride in
a mixture of NEt3 and N,N-dimethylformamide (DMF) gave hex-
anoamide derivative 10 as shown in Scheme 3. After purifica-
tion by silica gel column chromatography, more than one
product was identified by mass spectrometry; these products
differed in the number of attached C6H11O groups (Figure 6)
and their final separation was possible by passing the mixture
twice through a flash silica gel column. The purity of homooc-
ta-substituted 10 was confirmed by NMR and FTIR spectro-
scopic methods and by mass spectrometry (see the Experimen-
tal Section and the Supporting Information).
signed to n(C=O), d(N-H), and n(C-N) modes. Furthermore, n(Si-
O-Si) stretching appeared at 1222 cmꢀ1. It is also worth noting
that the absorption band in the range of siloxane Si-O-Si bond
vibrations was narrow, as shown in Figure 7. This phenomenon
is not common and is extremely important from the applica-
tion point of view.
In all cases, except 5, the presence of silanol groups was ex-
cluded. This was confirmed by the high stability of amide-de-
rivatives in the alkaline environment, in which the siloxane net-
work was maintained. This can be explained by the presence
of side-chains with large steric bulk. This contrasts with OAS-
POSS for which there is a high probability of the formation of
open cage-like structures depending on the environment.
Therefore, from the synthetic point of view, the amide-deriva-
tives possessing extended substituents stay in competition to
non-ramified octaaminopropylsilsesquioxanes structures, which
are prone to decomposition in solution.
To ascertain the presence of aminopropyl side-chains, all re-
actions were tested by using ninhydrin. Given that none of the
tests resulted in a violet color (in contrast to the to so-called
control), the presence of a primary amine was excluded. Pure
homoocta-substituted final product was confirmed by available
spectroscopic methods and by mass spectrometry (see the Ex-
perimental Section and the Supporting Information).
All amido-functionalized POSS compounds were character-
ized by using FTIR and multinuclear NMR (1H, 13C, 29Si) spectros-
copy, and mass spectrometry. In the infrared spectra, the
amide group gave specific absorption bands, for example, for
6 vibrations at 1649, 1547, and 1301 cmꢀ1 can be clearly as-
Moreover, all compounds were purified by using column
chromatography, which allowed for the separation of the
target compounds from side-products that do not hold fully
substituted side-chains. Such homo-substitution was unambig-
Figure 6. Examples of by-products identified during the reaction of hexanoyl chloride with 1 or 2.
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uously verified by mass spectrometry (see the Supporting In-
formation).
Conclusion
Thermal stability of amide-POSS 6–10 was also examined
under aerobic conditions (for TGA-DTA details see the Support-
ing Information). Generally, thermal decomposition occurred in
two steps. The first mass-loss corresponded to extrusion of the
side-chains. In the second step (>4008C), the siloxane cage
decomposed to SiO2, which was confirmed by FTIR spectrosco-
py. For 9, extrusions of side-chains occurred at lower tempera-
ture (1658C), but substitution of aryl ring in the para-position
increased this temperature, which, for 8, approached 3968C.
Decomposition temperatures for 4-substituted amide-deriva-
tives, and for hexanoamide 10, were higher compared with
1 and 2. For instance, decomposition of 1 occurred at 3148C.
No MS analysis of the volatiles was performed.
We have shown that salts derived from OAS-POSS containing
anions such as Clꢀ and CF3SO3ꢀ constitute ideal starting materi-
als for the controlled assembly of well-defined homooctaami-
do-functionalized POSS. By using sulfonide salt, we noticed
higher yields in the synthesis of amide-derivatives; for exam-
ple, for 6, yields of up to 97% were obtained. The applied syn-
thetic approach allowed various organic substituents (alkyl and
aryl) to be bound to the siloxane cage-like core. Careful optimi-
zation of the reaction conditions enabled the formation of un-
wanted by-products such as open cage-like polysilsesquiox-
anes to be avoided. We also demonstrated that by using the
wide range of organic substituents, it is possible to prepare
functionalized nanoparticles that are difficult to obtain by
using pure organic molecules without their attachment to the
siloxane core. Notably, the spherical-shaped particles do not
form agglomerates and are nicely separated. Such organic-in-
organic nanohybrids open up a wide field of applications, for
instance as a column fillers for advanced organic and inorganic
synthesis or efficient drug delivery systems. These kinds of ma-
terial can effectively replace functionalized silica, and add
unique characteristics including superior thermal, mechanical,
and chemical properties.
Compounds 6–10 were next used to obtained crystalline
nanoparticles. The resulting species were dissolved in dimethyl
sulfoxide (DMSO) and precipitated with deionized water. Such
suspensions were centrifuged at a speed of 5800 rpm and the
resulting powders were sonicated in methanol. The resulting
particles had a diameter of approximately 5 nm, spherical-like
(aryl substituents) shape, and did not form agglomerates as
shown in Figure 8. The only exception was nanoparticles of 10,
which had a fibrous-like morphology. This could be explained
by the presence of carbon side-chains attached to the POSS
core. The composition of all nanoparticles was confirmed by
EDS analysis (see the Supporting Information) and their crystal-
linity was examined by powder XRD and SAED measurements.
Experimental Section
General procedures and chemicals: All reactions were conducted
under N2 with the use of standard Schlenk techniques. Hexanes
and diethyl ether were distilled from Na, tetrahydrofuran was pre-
dried with NaOH and then distilled from Na/benzophenone; ace-
tone was distilled from P2O5; ethanol (anhydrous, J. T. Baker), meth-
anol, and chloroform (HPLC grade) were used as received. Dimeth-
yl sulfoxide and dimethylformamide (99.8% anhydrous, Aldrich)
were dried over activated 4 ꢁ molecular sieves prior to use. Benzo-
yl chloride (98%, Aldrich), 4-nitorobenzoyl chloride (98%, Aldrich),
4-fluorobenzoyl chloride (98%, Aldrich), hexanoyl chloride (99%,
Merck), (3-aminopropyl)triethoxysilane (99%, Aldrich), trifluoroace-
tic acid (98%, Aldrich), trifluoromethanesulfonic acid (98%, Al-
drich), triethylamine (99.5%, Aldrich), zinc dust (99,99%, Fluka), HCl
(36–38%, Avantor Performance Materials Poland S.A.), NaHCO3
(Avantor Performance Materials Poland S.A.) were used without fur-
ther purification unless stated otherwise. Chromium(III) acetylacet-
onate was prepared by following the described procedure.[24]
Methods: 1H and 13C NMR spectra were recorded with a Bruker
Avance 500 or a Bruker Avance III 600 spectrometer. 29Si NMR spec-
tra were recorded with a Bruker AMX-300 spectrometer using Wild-
mad’s PTFE-FEP (polytetrafluoroethylene/fluorinated ethylene poly-
propylene copolymer) 5 mm tube liners. Cr(acac)3 was added in
a concentration of approximately 10ꢀ2 molLꢀ as a shiftless relaxa-
tion agent. Chemical shifts are reported in parts per million (d)
downfield from tetramethylsilane and are referenced to residual
peaks of deuterated NMR solvents. Chemical shift values for
29Si{1H} NMR spectra were referenced to TMS or DSS. Assignments
are based on COSY, NOESY, HSQC, and HMBC correlation experi-
ments. Thin-layer chromatography (TLC) was performed on Merck
silica gel 60 F254 plates. Chromatograms were visualized by using
UV light (254 nm). For the detection of amine, the chromatograms
were first dipped in a 5% (w/v) solution of ninhydrin in 95% aque-
ous ethanol, and finally charred on a hotplate. Flash column chro-
Figure 8. Selected HR-TEM Images of 6 (a, b), 7 (c, d), 8 (e, f), 9 (g, h), and 10
(i) particles. Selected area electron diffraction patterns are placed as insets in
b, d, f, h images. Scale bars: a) 100 nm; b) 20 nm; c) 20 nm; d) 10 nm; e)
20 nm; f) 5 nm; g) 10 nm; h) 5 nm; i) 500 nm.
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matography was performed with Merck silica gel, grade 60, 230–
400 mesh. Elemental analyses were performed with a Vario EL III el-
ement analyzer. Infrared spectra were recorded in a KBr cell with
a Bruker Vertex 70 FTIR spectrometer. High-resolution and accurate
mass spectra were recorded with a Bruker apex ultra FTMS and
a Bruker microTOF-Q spectrometer using the electrospray tech-
nique. TG-DTA analyses were recorded with a Setaram SETSYS 16/
18 instrument. Samples for thermogravimetric characterization
were placed in open alumina crucibles in an air atmosphere. A
heating rate of 108C·minꢀ1 was applied and all samples were stud-
ied between 40 and 10008C. Samples for transmission electron mi-
croscopy (TEM) were prepared by dispersing the powder in etha-
nol and depositing the suspension on a holed carbon copper grid.
The images were obtained with a FEI Tecnai G2 F20 X-TWIN Trans-
mission Electron Microscope equipped with a Penta FET EDX de-
tector. Powders were characterized by recording X-ray powder dif-
fraction (XRD) patterns with a Bruker D8 ADVANCE diffractometer
equipped with a copper lamp (lCuKa =1.5406 ꢁ). Standard measure-
ments were done for 2q=5–508 with a 2q step of 0.0168 and
a counting time of 1 s.
1615 (m, dNH3), 1507 (m, nC-N), 1267 (s, nC-F), 1226 (m, nSi-C), 1138 (s,
nSi-O-Si), 103 (s, nSO3), 640 (s, nS-N) cmꢀ1; HRMS (ESI+, TOF, 5% AcOH/
H2O): m/z (%): 881.2898 (30) {calcd. for [M+Hꢀ8CF3SO3H]+
881.2871}, 441.1572 (100) {calcd. for [M+2Hꢀ8CF3SO3H]2+
441.1472}, 294.4400 (20) {calcd. for [M+3Hꢀ8CF3SO3H]3+ 294.4339};
elemental analysis calcd (%) for C32H72F24N8O36S8Si8 (2081.67): C
18.46, H 3.49, N 5.38, S 12.32; found: C 18.40, H 3.46, N 5.37, S
12.30. Temperature of decomposition to SiO2 (determining by TGA
measurement), residue yield: 4288C, 23.00% (calcd 23.09%).
Synthesis of 3: Trifluoroacetic acid aqueous solution (5%, 68.4 mL,
30.0 mmol) was added at RT to (3-aminopropyl)triethoxysilane
(3.51 mL, 3.26 g, 15.0 mmol). The resulting solution was stirred for
2 h and then kept at 508C in an open system until the solvent
completely evaporated (usually 2–3 h). The crude product was
then maintained at 1008C for 1 h. The product was washed with
acetone (4ꢂ20 mL), and then dried under vacuum (258C, 0.5 mbar)
to give 3 (3.03 g, 90%) as a hygroscopic glassy product. 1H NMR
(500 MHz, [D6]DMSO, 208C): d=8.21--7.86 (br, 24H; NH3+), 2.87–
2.72 (br, 16H; CH2NH3+), 1.70–1.54 (br, 16H; SiCH2CH2CH2NH3+),
0.74–0.50 ppm (br, 16H; SiCH2); 13C NMR (126 MHz, [D6]DMSO,
208C): d=159.5 (q, 2J(C,F)=32 Hz; CF3COOꢀ), 117.4 (q, 1J(C,F)=
297 Hz; CF3COOꢀ), 41.4 (s; SiCH2CH2CH2NH3+), 21.0 (s;
SiCH2CH2CH2NH3+), 8.6 ppm (s; SiCH2CH2CH2NH3+); 29Si{1H} NMR
(59.6 MHz, [D6]DMSO, 208C): d=ꢀ66.65 ppm (s, T3); FTIR (KBr pel-
lets): n˜ =2944 (s, nN-H), 1674 (m, dNH3), 1533 (s, nco), 1473 (m, nC-N),
1267 (s, nC-F), 1132 (s, nSi-O-Si) cmꢀ1; HRMS (ESI+, TOF/CH3OH): m/z
(%): 881.2862 (24) {calcd. for [M+Hꢀ8CF3COOH]+ 881.2871},
441.1475 (100) {calcd. for [M+2Hꢀ8CF3COOH]2+ 441.1469}; ele-
mental analysis calcd (%) for C40H72F24N8O28Si8 (1793.76): C 26.78, H
4.05, N 6.25; found: C 26.75, H 4.01, N 6.21. Temperature of decom-
position to SiO2 (determining by TGA measurement), residue yield:
3538C, 26.70% (calcd 26.60%).
Synthesis of 1: Concentrated HCl (200 mL) was carefully added to
a continuously stirring solution of (3-aminopropyl)triethoxysilane
(150 mL, 139.4 g, 0.641 mol) in MeOH (1.0 L) in a 2.0 L round-
bottom flask. The flask was capped and the solution was stirred at
RT for 4 weeks at 258C. A product started to crystallize after
2 weeks. Pure 1 was obtained by filtering the reaction mixture,
washing with cold MeOH, and drying under vacuum (258C,
0.5 mbar) in 45% yield (42.3 g). An additional portion of 1 (6.58 g,
7%) was collected by adding ethanol to the filtrate. Analytically
pure product could be obtained as a white microcrystalline
powder by recrystallization from hot MeOH. 1H NMR (500 MHz,
[D6]DMSO, 208C): d=8.23 (s, 24H; NH3+), 2.79 (t, 3J(H,H)=7.9 Hz,
16H; CH2NH3+), 1.74 (m, 16H; SiCH2CH2CH2NH3+), 0.75 ppm (t,
3J(H,H)=8.6 Hz, 16H; SiCH2); 13C{1H} NMR (126 MHz, D2O, 208C):
d=41.7 (s, SiCH2CH2CH2NH3+), 20.6 (s, SiCH2CH2CH2NH3+), 8.7 ppm
(SiCH2CH2CH2NH3+); 29Si{1H} NMR ([D6]DMSO, 59.6 MHz, 208C): d=
ꢀ66.52 ppm (s, 1J(Si,C)=45 Hz; T3); FTIR (KBr pellets): n˜ =3041 (s,
nN-H), 2935 (m, nC-H), 2872 (m, nC-H), 1615 (m, dNH3), 1500 (m, nC-N),
1237 (m, nSi-C), 1116 (s, ncage-asymSi-O-Si), 941 (m, ncage-symSi-O-Si), 798 (w, dSi-
Synthesis of 4
Method A: Amberlite IRA-400 ion-exchange resin (37.0 g) was pre-
pared by washing with water (4ꢂ200 mL), 1m NaOH (3ꢂ200 mL),
water (6ꢂ200 mL), and MeOH (elution solvent, 6ꢂ200 mL). The
resin was suspended in MeOH (200 mL) and chilled (ꢀ188C, 5 h)
before use. Half of the resin beads were loaded onto a column
(3.0 cm outside diameter) and the other half was used to prepare
a suspension of 1 (0.500 g, 0.426 mmol) in a minimum amount of
eluent (ca. 5 mL) at ꢀ188C. Elution across the column produced
a solution of 4, which tested negative for chloride (by addition of
AgNO3). The solvent was removed with nitrogen flow at 08C and
then evaporated (08C, 0.5 mbar) to afford 4 (50%, 0.200 g) as a yel-
lowish resin. Compound 4 should be freshly prepared before use
and stored as a MeOH solution at ꢀ188C. 1H NMR (500 MHz,
MeOD, 208C): d=2.60 (t, 3J(H,H)=7.9 Hz, 16H; CH2NH2), 1.54 (m,
16H; SiCH2CH2CH2NH2), 0.63 ppm (t, 3J(H,H)=8.6 Hz, 16H; SiCH2);
C), 701 (m, dO-Si-O) cmꢀ1
; HRMS (ESI+, TOF/MeOH): m/z (%):
881.2898 (25) {calcd. for [M+Hꢀ8HCl]+ 881.2871}, 441.1490 (100)
{calcd. for [M+2Hꢀ8HCl]2+ 441.1472}, 294.4340 (28) {calcd. for
[M+3Hꢀ8HCl]3+ 294.4339}; elemental analysis calcd (%) for
C24H72O12Si8N8Cl8 (1173.18): C 24.57, H 6.19, N 9.55, Cl 24.18; found:
C 24.51, H 6.15, N 9.54, Cl 24.10. Temperature of decomposition to
SiO2 (determined by TGA measurement), residue yield: 3148C,
40.70% (calcd 40.97%).
Synthesis of 2: CF3SO3H (0.5m aqueous solution, 30 mL,
15.0 mmol) was added with stirring at RT to (3-aminopropyl)trie-
thoxysilane (2.34 mL, 2.17 g, 10.0 mmol). The resulting solution was
further stirred for 3 h and then heated to approximately 508C in
an open beaker until the solvent had completely evaporated (3 h).
The crude product was heated at 1008C for 1 h, then cooled to RT
and acetone (100 mL) was added. The precipitate was isolated by
filtration, washed with acetone (3ꢂ10 mL), and dried in a vacuum
oven (508C, 20 mbar, 48 h) to give 2 (2.24 g, 95%) as a white
powder. 1H NMR (500 MHz, [D6]DMSO, 208C): d=7.57 (s, 24H;
NH3+), 2.75 (t, 3J(H,H)=7.2 Hz, 16H; CH2NH3+), 1.56 (m, 16H;
SiCH2CH2CH2NH3+), 0.66 ppm (t, 3J(H,H)=8.6 Hz, 16H; SiCH2);
13C{1H} NMR (126 MHz, D2O, 208C): d=122.5 (q, 1J(C,F)=317 Hz;
CF3SO3ꢀ), 44.4 (s; SiCH2CH2CH2NH3+), 23.3 (s; SiCH2CH2CH2NH3+),
11.3 ppm (s; SiCH2CH2CH2NH3+); 29Si{1H} NMR (59.6 MHz, [D6]DMSO,
208C): d=ꢀ66.53 ppm (s; T3); FTIR (KBr pellets): n˜ =3041 (s, nN-H),
13C{1H} NMR
(126 MHz,
[D6]DMSO,
208C):
d=44.4
(s;
SiCH2CH2CH2NH2), 26.6 (s; SiCH2CH2CH2NH2), 9.8 ppm (s;
SiCH2CH2CH2NH2); 29Si{1H} NMR (59.6 MHz, [D6]DMSO, 208C): d=
ꢀ66.53 ppm (s; T3); FTIR (KBr pellets): n˜ =3041 (s, nN-H), 2935 (m, nC-
H), 2872 (m, nC-H), 1615 (m, dNH2), 1500 (m, nC-N), 1237 (m, nSi-C), 1116
(s, nring-asym
), 941 (m, nring-sym
Si-O-Si
), 798 (w, dSi-C), 701 (m, dO-Si-
Si-O-Si
O) cmꢀ1; HRMS (ESI+, TOF/CH3OH): m/z (%): 881.2916 (45) {calcd.
for [M+H]+ 881.2871}, 441.1635 (100) {calcd. for [M+2H]2+
441.1469}, 294.4442 (20) {calcd. for [M+3H]3+ 294.4339}; elemental
analysis calcd (%) for C24H64N8O12Si8 (881.50): C 32.70, H 7.32, N
12.71; found: C 32.69, H 7.35, N 12.69, Cl 0. Temperature of decom-
position to SiO2 (determined by TGA), residue yield: 2108C, 54.60%
(calcd 54.53%).
Method B: The procedure was analogous to that described in
Method A with the use of 2 (0.510 g, 0.245 mmol) instead of 1.
Chem. Eur. J. 2014, 20, 15966 – 15974
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Yield: 0.190 g (88%). Elemental analysis calcd (%) for C24H64N8O12Si8
(881.50): C 32.70, H 7.32, N 12.71; found: C 32.68, H 7.40, N 12.75.
a water bath for 1 h, then the solution was neutralized by adding
saturated NaHCO3 (200 mL). Filtration followed by washing with
a 1m solution of NaOH to remove Zn(OH)2, and a second filtration
and washing with distilled water (3ꢂ35 mL), and drying in vacuo
(258C, 0.5 mbar) afforded 7 (0.0790 g, 90%) as a yellow solid.
1H NMR (500 MHz, [D6]DMSO, 208C): d=8.11 (t, 3J(H,H)=5.5 Hz,
8H; 8NH), 7.57 (d, J(H,H)=8.7 Hz, 16H; 8m-Ph), 6.51 (d, J(H,H)=
Synthesis of 5·8HCl: A solution of 4 (0.150 g, 0.170 mmol) in
MeOH (50 mL) was added to a solution of NaHCO3 (2.50 g,
19.1 mmol) in double-distilled H2O (50 mL), and the mixture was
stirred for 6 h. MeOH and water were removed under vacuum
(258C, 0.5 mbar) to afford a yellow resin of 5. The product was
washed with water (3ꢂ30 mL) and 0.5m methanolic solution of
HCl (0.34 mL, 0.170 mmol) was added to give 5·8HCl (0.196 g,
3
8.7 Hz, 16H; 8o-Ph), 5.59 (s, 16H; 8NH2), 3.14 (dt, J(H,H)=6.5 Hz,
3J(H,H)=5.9 Hz, 16H; 8SiCH2CH2CH2NH2), 1.53 (m, 16H;
8SiCH2CH2CH2NH2),
0.58 ppm
(t,
3J(H,H)=7.8 Hz,
16H;
1
95%). H NMR (500 MHz, [D6]DMSO, 208C): d=8.04 (s, 24H; NH3+),
8SiCH2CH2CH2NH2); 13C{1H} NMR (126 MHz, [D6]DMSO, 208C): d=
166.3 (s, CO), 151.4 (s, CN), 128.6 (s, i-Ph), 121.3 (s, o-Ph), 112.5 (s,
m-Ph), 41.5 (s, CH2N), 22.6 (s, SiCH2CH2), 8.8 ppm (s, SiCH2);
29Si{1H} NMR (59.6 MHz, [D6]DMSO, 208C): d=ꢀ66.02 ppm (s; T3);
FTIR (KBr pellets): n˜ =3418 (s, nN-H), 2935 (m, nC-H), 2872 (m, nC-H),
3.64 (br, 4H; OH), 2.80 (br, 16H; CH2NH3+), 1.62 (br, 16H;
SiCH2CH2CH2NH3+), 0.67 (br, 8H; HOSiCH2), 0.64 ppm (br, 8H;
O3SiCH2); 13C{1H} NMR (126 MHz, [D6]DMSO, 208C): d=41.7 (s;
SiCH2CH2CH2NH3+), 20.6 (s; SiCH2CH2CH2NH3+), 9.0 (s;
O3SiCH2CH2CH2NH3+),
8.7 ppm
(s;
HOSiCH2CH2CH2NH3+);
29Si{1H} NMR ([D6]DMSO, 59.6 MHz, 208C): d=ꢀ65.90 (s; T2),
ꢀ68.55 ppm (s; T3); FTIR (KBr pellets): n˜ =3436 (s, nO-H), 3041 (s, nN-
H), 1610 (m, dNH3), 1500 (m, dNH3), 1136 (s, nSi-O-Si), 990 (m, nSi-OH), 799
(w, dSi-C), 554 (w,dO-Si-O) cm–1; HRMS (ESI+, TOF): m/z (%): 917.230
(100) {calcd. for [M+Hꢀ8HCl]+ 917.308}; elemental analysis calcd
(%) for C24H76O14Si8N8Cl8 (1209.21): C 23.84, H 6.33, N 9.27, Cl 23.46;
found: C 23.41, H 6.38, N 9.20, Cl 23.40. Temperature of decompo-
sition to SiO2 (determined by TGA measurement), residue yield:
3248C, 41.00% (calcd 40.97%).
1649(s, nC O), 1598 (s, nAr), 1547 (s, dNH), 1488 (m, nAr), 1301 (m, nC-N),
=
1111 (s, nring-asymSi-O-Si), 1015 (m, dAr), 870 (m, nC-NH2), 844 (m, dAr-NO2),
781 (w, dSi-C), 718 (w, dO-Si-O), 467 (w, dSi-O-Si) cmꢀ1; HRMS (ESI+, TOF/
CH3OH): m/z (%): 1855.5745 (6) {calcd. for [M+Na]+ 1855.5660},
1833.5829 (12) {calcd. for [M+H]+ 1833.5840}, 939.2903 (100)
{calcd. for [M+2Na]2+ 939.2776}, 917.3066 (40) {calcd. for [M +
2H]2+ 917.2956}; elemental analysis calcd (%) for C80H104N16O20Si8
(1834.46): C 52.38, H 5.71, N 12.22; found: C 52.29, H 5.68, N 12.12.
Temperature of decomposition to SiO2 (determining by TGA mea-
surement), residue yield: 5948C, 26.14% (calcd 26.20%).
Synthesis of 6
Synthesis of 8
Method A: 4-Nitrobenzoyl chloride (0.080 g, 0.422 mmol, 8.8 equiv)
was added dropwise to a solution of 1 (0.0563 g, 0.0480 mmol)
and NEt3 (0.124 mL, 90.0 mg, 0.888 mmol, 18.5 equiv) in DMF
(10 mL). After stirring overnight at ꢀ188C, the crude product was
precipitated by slow addition to 1.0m aqueous HCl (75 mL, 08C).
Filtration, extraction into DMSO (10 mL), precipitation with cold, sa-
turated NaHCO3 (75 mL), washing with water, and drying in vacuo
(258C, 0.5 mbar) afforded a yellow solid of crude 6 (0.0931 g, 93%),
which was purified by flash column chromatography (hexane/
EtOH/MeOH, 8:1:1 v/v/v) to give 6 (0.090 g, 90% overall yield) as
a yellowish solid (Rf =0.16). 1H NMR (600 MHz, [D6]DMSO, 208C):
d=8.72 (s, 8H; 8NH), 8.13 (dd, 3J(H,H)=8.7 Hz, 5J(H,H)=1.7 Hz,
16H; 8m-Ph), 7.94 (dd, 3J(H,H)=8.8 Hz, 5J(H,H)=1.3 Hz, 16H; 8o-
Method A: 4-Fluorobenzoyl chloride (0.051 mL, 0.0684 g,
0.423 mmol, 8.8 equiv),
1 (0.0563 g, 0.0480 mmol), and NEt3
(0.124 mL, 0.0900 g, 0.888 mmol, 18.5 equiv) were combined in
a procedure analogous to that for 6. Analytically pure 8 was ob-
tained by dissolving crude 8 in DMSO and precipitation with water.
The white precipitate was centrifuged and dried in vacuo (258C,
0.5 mbar) to yield 8 (0.0400 g, 45%) as a white solid. 1H NMR
(500 MHz, [D6]DMSO, 208C): d=8.44 (s, 8H; 8NH), 7.85 (m, 16H;
8m-Ph), 7.20 (m, 16H; 8o-Ph), 3.19 (m, 16H; 8SiCH2CH2CH2NH), 1.58
(m, 16H; 8SiCH2CH2CH2NH), 0.64 ppm (t, 3J(H,H)=6.8 Hz, 6H;
8SiCH2CH2CH2NH); 13C{1H} NMR (126 MHz, DMSO, 208C): d=165.2
(s, CO), 163.7 (d, 1J(C,F)=249.7 Hz; CF), 131.0 (s, i-Ph), 129.7 (d,
3J(C,F)=8.7 Hz; o-Ph), 115.0 (d, 2J(C,F)=22 Hz; m-Ph), 41.7 (s,
CH2N), 22.4 (s, SiCH2CH2), 8.9 ppm (s, SiCH2); 29Si{1H} NMR
(59.6 MHz, [D6]DMSO, 208C): d=ꢀ65.98 ppm (s; T3); FTIR (KBr pel-
3
Ph), 3.21 (t, J(H,H)=6.9 Hz, 16H; 8SiCH2CH2CH2NH), 1.62 (m, 16H;
8SiCH2CH2CH2NH),
0.68 ppm
(t,
3J(H,H)=6.8 Hz,
16H;
8SiCH2CH2CH2NH); 13C{1H} NMR (151 MHz, [D6]DMSO, 208C): d=
164.4 (s, CO), 148.6 (s, CN), 140.2 (s, i-Ph), 128.6 (s, o-Ph), 123.2 (s,
m-Ph), 41.9 (s, CH2N), 22.4 (s, SiCH2CH2), 9.4 ppm (s, SiCH2);
29Si{1H} NMR (59.6 MHz, [D6]DMSO, 208C): d=ꢀ68.03 ppm (s; T3);
FTIR (KBr pellets): n˜ =3418 (s, nN-H), 2935 (m, nC-H), 2872 (m, nC-H),
lets): n˜ =3320 (s, nN-H), 2934 (m, nC-H), 2873 (m, nC-H), 1639 (s, nC O),
=
1604 (m, nAr), 1548 (m, dNH), 1504 (s, nAr), 1290 (m, nC-N), 1236 (m, nC-
F), 1121 (s, nring-asymSi-O-Si), 849 (s, nAr-H), 765 (m, dSi-C), 601 (m, nAr-F),
469 (w, dSi-O-Si) cmꢀ1; HRMS (ESI+, TOF/CH3Cl): m/z (%): 1857.4103
(14) {calcd. for [M+H]+ 1857.4214}, 929.2262 (100) {calcd. for
[M+2H]2+ 929.2143}; elemental analysis calcd (%) for
C80H88N8O20Si8F8 (1858.27): C 51.71, H 4.77, N 6.03; found: C 51.74,
H 4.74, N 6.00. Temperature of decomposition to SiO2 (determining
by TGA measurement), residue yield: 4638C, 25.84% (calcd
25.87%).
1649 (s, nC O), 1598 (s, nAr), 1547 (s, dNH), 1524 (s, nasymN=O), 1488 (m,
=
nAr), 1347 (s, nsymN=O), 1301 (m, nC-N), 1110 (s, nring-asymSi-O-Si), 1015 (m,
dAr), 870 (m, nC-NO2), 844 (m, dAr-NO2), 781 (w, dSi-C), 718 (w, dO-Si-O), 467
(w, dSi-O-Si) cmꢀ1; HRMS (ESI+, TOF/MeOH): m/z (%): 2095.3525 (30)
{calcd. for [M + Na]+ 2095.3593}, 1059.1848 (100) {calcd. for [M +
2Na]2+ 1059.1743}; elemental analysis calcd (%) for C80H88N16O36Si8
(2074.32): C 46.32, H 4.28, N 10.80; found: C 46.36 H 4.24, N 10.76.
Temperature of decomposition to SiO2 (determining by TGA mea-
surement), residue yield: 5818C, 23.21% (calcd 23.17%).
Method B: The procedure was analogous to that described in
Method A with the use of 2 (0.100 g, 0.0480 mmol) instead of 1.
Yield: 0.0424 g (48%). Elemental analysis calcd (%) for
C80H88N8O20Si8F8 (1858.27): C 51.71, H 4.77, N 6.03; found: C 51.65,
H 4.76, N 6.01.
Method B: The procedure was analogous to that described in
Method A with the use of 2 (0.100 g, 0.0480 mmol) instead of 1.
Yield (crude): 0.0962 g (97%). Final yield: 0.0900 g (90%). Elemental
analysis calcd (%) for C80H88N16O36Si8 (2074.32): C 46.32, H 4.28, N
10.80; found: C 46.24, H 4.32, N 10.84.
Synthesis of 9
Method A: Benzoyl chloride (0.100 mL, 0.121 g, 0.845 mmol,
8.8 equiv) was added dropwise to a solution of
1 (0.113 g,
Synthesis of 7: A 100 mL flask fitted with a reflux condenser was
0.0960 mmol) and NEt3 (0.247 mL, 0.179 g, 1.78 mmol, 18.5 equiv)
in DMF (8 mL, 08C). After stirring overnight, the crude product was
precipitated by slow addition to 1m HCl (aqueous, 140 mL, 08C).
Filtration, dissolution in DMSO (16 mL), precipitation with cold sa-
charged with
6 (0.100 g, 0.0480 mmol), zinc dust (0.032 g,
0.490 mmol, 10 equiv) and concentrated hydrochloric acid (36–
38%, 0.127 mL, 1.47 mmol, 3 equiv). The mixture was heated in
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15973
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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turated NaHCO3 (140 mL), washing with water and drying in vacuo
(258C, 0.5 mbar) gave 9 (yield 1, crude product: 0.134 g, 81%) as
a yellowish solid. The residue was purified by flash column chroma-
tography (CH3CN/EtOH, 1:1 v/v; Rf =0.38) to give 9 (yield 2, after
purification using flash column chromatography: 0.091 g, 55%) as
a white solid. 1H NMR (500 MHz, CDCl3, 208C): d=8.33 (s, 8H;
composition to SiO2 (determining by TGA measurement), residue
yield: 4448C, 28.85% (calcd 28.84%).
Method B: The procedure was analogous to that in Method A with
the use of 2 (0.354 g, 0.170 mmol) instead of 1. Yield (crude):
0.232 g (82%). Final yield: 0.213 g (75%). Elemental analysis calcd
(%) for C72H144N8O20Si8 (1666.64): C 51.89, H 8.71, N 6.72; found: C
51.92, H 8.75, N 6.68.
3
5
8NH), 7.72 (dd, J(H,H)=8.0 Hz, J(H,H)=1.3 Hz, 16H; 8o-Ph,), 7.34
3
(t, J(H,H)=7.4 Hz, 8H; 8p-Ph), 7.23 (m, 16H; 8m-Ph), 3.31 (m, 16H;
8CH2N), 1.66 (m, 16H; 8SiCH2CH2), 0.62 ppm (t, 3J(H,H)=6.8 Hz,
16H; 8SiCH2); 13C{1H} NMR (126 MHz, CDCl3, 208C): d=166.2 (s,
CO), 134.5 (s, i-Ph), 130.9 (s, p-CH), 128.0 (s, m-Ph), 127.0 (s, o-Ph),
41.6 (s, CH2N), 23.3 (s, SiCH2CH2), 8.7 ppm (s, SiCH2); 29Si{1H} NMR
(CDCl3, 59.6 MHz, RT): d=ꢀ68.28 ppm (s; T3); FTIR (KBr pellets): n˜ =
Acknowledgements
This work was supported by the National Research Centre
(Grant No. 2013/09/D/ST8/03995).
3410 (s, nN-H), 2928 (m, nC-H), 1638 (s, nC O), 1603 (m, nAr), 1544 (s,
=
dNH), 1488 (m, nAr), 1311 (m, nC-N), 1119 (s, nring-asymSi-O-Si), 1028 (m,
dAr), 802 (w, dSi-C), 694 (w, dO-Si-O), 473 (w, dSi-O-Si) cmꢀ1; HRMS (ESI+,
TOF/MeOH): m/z (%): 1713.4890 (21) {calcd. for [M+H]+ 1713.4968},
879.2429 (12) {calcd. for [M+2Na]2+ 879.2340}, 857.2631 (100)
{calcd. for [M+2H]2+ 857.2520}; elemental analysis calcd (%) for
C80H96N8O20Si8 (1714.40): C 56.05, H 5.64, N 6.54; found: C 56.09, H
5.67, N 6.66. Temperature of decomposition to SiO2 (determining
by TGA measurement), residue yield: 4228C, 28.00% (calcd
28.04%).
Keywords: nanoparticles · nanostructures · organic–inorganic
composites · solid-state structures · silicon
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Method B: The procedure was analogous to that described in
Method A with the use of 2 (0.200 g, 0.0960 mmol) instead of 1.
Yield (crude): 0.148 g (90%). Final yield: 0.138 g (84%). Elemental
analysis calcd (%) for C80H96N8O20Si8 (1714.40): C 56.05, H 5.64, N
6.54; found: C 56.08, H 5.68, N 6.64.
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Synthesis of 10
Method A: Hexanoyl chloride (0.383 mL, 0.374 g, 2.77 mmol,
16.3 equiv) was added dropwise to a suspension of 1 (0.200 g,
0.170 mmol) and NEt3 (0.626 mL, 0.455 g, 4.49 mmol, 26.4 equiv) in
DMF (8 mL, 08C). After stirring overnight, the crude product was
precipitated by slow addition to 1m aqueous HCl (140 mL, 08C).
Filtration, extraction with DMSO (16 mL), precipitation with cold sa-
turated NaHCO3 (140 mL), washing with water and drying in vacuo
(258C, 0.5 mbar) afforded 10 (yield 1, crude product: 0.180 g, 64%)
as a white solid. The residue was purified by flash column chroma-
tography (Et2O/hexane, 1:1 v/v) to afford 10 (yield 2, after purifica-
tion using flash column chromatography: 0.178 g, 63%) as a white
solid. Rf =0.56 (Et2O/hexane, 1:1 v/v); 1H NMR (500 MHz, MeOD,
3
208C): d=7.92 (s, 8H; NH), 3.15 (t, J(H,H)=7.0 Hz, 16H; CH2NH),
2.19 (t, 3J(H,H)=7.4 Hz, 16H; C(O)CH2), 1.62 (m, 16H;
SiCH2CH2CH2NH), 1.59 (m, 16H; C(O)CH2CH2), 1.36, 1.32 (m, 32H;
CH2CH2CH2CH3 and CH2CH2CH2CH3), 0.92 (t, 3J(H,H)=7.0 Hz, 24H;
CH3), 0.65 ppm (t, 3J(H,H)=8.4 Hz, 16H; SiCH2); 13C{1H} NMR
(126 MHz, MeOD, 208C): d=176.2 (s, C=O), 43.0 (s,
SiCH2CH2CH2NH), 37.2 (s, C(O)CH2), 32.6 (s, CH2CH2CH2CH3),26.9 (s,
C(O)CH2CH2CH2CH2CH3), 24.1 (s, SiCH2CH2CH2NH), 23.5 (s,
CH2CH2CH2CH2CH3), 14.5 (s, CH3), 10.7 ppm (s, SiCH2CH2CH2NH);
29Si{1H} NMR (59.6 MHz, CDCl3, 208C): d=ꢀ66.29 ppm (s; T3); FTIR
(KBr pellets): n˜ =3278 (s, nN-H), 2931 (m, nC-H), 2871 (m, nC-H), 1636 (s,
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nC O), 1558 (s, dNH), 1457 (w), 1383 (m, nC-N), 1272 (w, nC-C), 1122 (s,
=
nring-asymSi-O-Si), 698 (w, dO-Si-O), 472 (w, dSi-O-Si) cmꢀ1; HRMS (ESI+, FT+
MS/MeOH): m/z (%): 1703.8530 (6) {calcd. for [M+K]+ 1703.8283},
1687.8586 (26) {calcd. for [M+Na]+ 1687.8543}, 1665.8726 (10)
{calcd. for [M+H]+ 1666.8744}, 871.9043 (6) {calcd. for [M+2K]2+
871.8967}, 855.9257 (85) {calcd. for [M+2Na]2+ 855.9228}, 833.4421
(100) {calcd. for [M+2H]2+ 833.9408}, 577.9381 (5) {calcd. for
[M+3Na]3+ 577.9440}, 555.9649 (5) {calcd. for [M+3H]3+ 555.9623};
elemental analysis calcd (%) for C72H144N8O20Si8 (1666.64): C 51.89,
H 8.71, N 6.72; found: C 51.88, H 8.72, N 6.75. Temperature of de-
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in Inorganic Syntheses, Vol. 5 (Ed.: T. Moeller), Wiley, Hoboken, NJ, USA,
2007, DOI: 10.1002/9780470132364.ch35.
Received: June 27, 2014
Published online on October 10, 2014
Chem. Eur. J. 2014, 20, 15966 – 15974
www.chemeurj.org
15974
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim