Superhydrophobic polyoxometalate/calixarene inorganic-organic hybrid materials with highly efficient desulfurization ability

Article abstract of DOI:10.1002/ejic.201301407

In this paper, imidazole-based ionic liquids with different alkyl chains were covalently grafted onto calix[4]arene, which resulted in the formation of 4-6 with the molecular formula [C₄₄H₅₆O ₄·2C₄H₆N₂(CH ₂)_n]·2Br [n = 5 (4), n = 8 (5), n = 12 (6)]. Ion exchange of 4-6 with Na₉EuW₁₀O₃₆· 32H₂O (denoted EuW₁₀) led to the formation of new inorganic-organic hybrid materials 7-9 with a molecular composition of [C ₄₄H₅₆O₄·2C₄H ₆N₂(CH₂)_n] _4.5·EuW₁₀O₃₆·xH₂O [n = 5, x = 10 (7); n = 8, x = 7 (8); n = 12, x = 20 (9)]. Contact angles above 139° suggested superhydrophobicity of the resulting hybrid materials 7-9. Sulfur removal of dibenzothiophene by applying hybrid materials 7-9 as heterogeneous catalytic systems indicated that deep desulfurization could be achieved at 70°C in 7, 5.5, and 5 min, respectively. Hybrid materials 7-9 were demonstrated to be highly efficient and selective desulfurization systems that could be reused more than 10 times without a clear decrease in reactivity. Ion-exchange of compounds with the formula [C₄₄H₅₆O ₄·2C₄H₆N₂(CH ₂)_n]·2Br by Na₉EuW₁₀O ₃₆·32H₂O results in the formation of inorganic-organic hybrid materials, which exhibit superhydrophobicity with a contact angle of >139°. The application of these hybrids in extractive catalytic oxidative desulfurization indicates that they are highly efficient and selective heterogeneous catalytic systems. Copyright

Full text of DOI:10.1002/ejic.201301407

SHORT COMMUNICATION
DOI:10.1002/ejic.201301407
Superhydrophobic Polyoxometalate/Calixarene Inorganic–
Organic Hybrid Materials with Highly Efficient
Desulfurization Ability
Xu-Miao Zhou,[a][‡] Wei Chen,[a][‡] and Yu-Fei Song*[a]
Keywords: Polyoxometalates / Calixarenes / Hydrophobicity / Organic–inorganic hybrid composites
In this paper, imidazole-based ionic liquids with different
alkyl chains were covalently grafted onto calix[4]arene,
which resulted in the formation of 4–6 with the molecular
139° suggested superhydrophobicity of the resulting hybrid
materials 7–9. Sulfur removal of dibenzothiophene by apply-
ing hybrid materials 7–9 as heterogeneous catalytic systems
indicated that deep desulfurization could be achieved at
70 °C in 7, 5.5, and 5 min, respectively. Hybrid materials 7–9
formula [C44H
56
O
4
·2C
4
H
6
N
2
(CH
2
)
n
]·2Br [n = 5 (4), n = 8 (5),
EuW10 36·32H
n = 12 (6)]. Ion exchange of 4–6 with Na
9
O
2
O
(denoted EuW10) led to the formation of new inorganic–or- were demonstrated to be highly efficient and selective de-
ganic hybrid materials 7–9 with a molecular composition of
sulfurization systems that could be reused more than 10
times without a clear decrease in reactivity.
[
C
44
H O
56 4
4 6 2 2 n 2
·2C H N (CH ) ]4.5·EuW10O36·xH O [n = 5, x = 10
(
7); n = 8, x = 7 (8); n = 12, x = 20 (9)]. Contact angles above
Introduction
In recent years, a number of POMs have shown great
potential as catalytic oxidative desulfurization catalysts.
Calixarene is a macrocyclic receptor with phenol units Sulfur-containing compounds in transportation fuels such
linked to methylene groups at the o,oЈ-positions.[1] As the as gasoline and diesel oil can be converted into SO during
x
third generation of host compounds, in addition to well- combustion, which is not only responsible for the formation
known crown ethers and cyclodextrins, calixarene has been of smog, sour gases, and acid rain, but it also poisons noble
actively studied and utilized as a building block, as it shows metal catalysts that can reduce SOx emissions. The cur-
advantages over other molecular systems, including the fact rently adopted method in industry is catalytic hydrode-
[
6]
that it has a hydrophobic cavity and that it can be easily sulfurization (HDS). Although HDS is efficient in remov-
modified by adding organic groups at both the lower and ing thiols, sulfides, and disulfides from fuels, it is less effec-
[
2]
upper rims.
tive in removing refractory sulfur-containing compounds
Polyoxometalates (POMs) are a class of early transition such as dibenzothiophene (DBT) and its derivatives.[ The
metal oxides of V, Mo, W, Nb, and so on. POMs cover an harsh operating conditions and high capital cost of HDS
enormous size range and show a diverse range of dynamic largely restrict its application in the long run. Under such
molecular structures, a number of unique physical and circumstances, deep desulfurization without the use of hy-
7]
[
3]
chemical properties, and a wide range of applications.
drogen, high pressures, and high temperatures is urgently
POMs, as transferable building blocks, hold considerable needed. One desulfurization method that has been demon-
promise for the controlled assembly of large nanostructures strated to be potentially promising as an alternative to HDS
and framework materials.[ Among the large domains of is extractive catalytic oxidative desulfurization (ECODS), in
4]
POMs, lanthanide-containing POMs with unique 4f-shell which an ionic liquid (IL) is used as the extractant, H O2
2
electrons show great potential as functional materials. For is used as the oxidant, and some efficient desulfurization
[
8]
example, EuW10 shows a sandwich structure and has dem- catalysts such as POMs are used.
onstrated its application as a fluorescent and catalytic mate-
rial.
The combination of calixarene with metal–organic or in-
organic clusters gives enormous structural diversity and
leads to fascinating multifunctional assemblies owing to
their inherently different natures and possible synergetic ef-
[
5]
[
a] State Key Laboratory of Chemical Resource Engineering,
Beijing University of Chemical Technology,
Beijing 100029, P. R. China
[
9]
fects. For example, Konishi et al. reported the first porous
organic–inorganic assemblies constructed from Keggin
E-mail: songyufei@hotmail.com
+
[10]
songyf@mail.buct.edu.cn
POM anions and calixarene–Na complexes that display
reversible guest sorption with retention of the original
framework. In 2007, the same group reported interesting
calix[4]arene-based hybrids that provide tunable hydro-
http://sci.buct.edu.cn/szll/jsml/wlhxx/9778.htm
‡] These authors contributed equally to this work
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201301407.
[
Eur. J. Inorg. Chem. 2014, 812–817
812
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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SHORT COMMUNICATION
phobic micropores for the facile recognition of the shape of
simple alkanes and alkenes.[ Liao et al. reported a new
11]
hybrid based on the p-tert-butylthiacalix[4]arene-supported
[
12]
high-nuclearity inorganic cluster and Keggin POMs.
Inspired by the above contributions, herein, inorganic–
organic hybrid materials 7–9 were synthesized by ion ex-
change of 4–6 [C H O ·2C H N (CH ) ]·2Br [denoted
4
4
56
4
4
6
2
2 n
Calix-IL-Br, n = 5 (4), n = 8 (5), n = 12 (6)] with
Na EuW O ·32H O (denoted EuW ). The resulting hy-
9
10 36
2
10
brid materials exhibited superhydrophobicity and good ex-
tractive catalytic oxidative desulfurization ability under
mild conditions.
Results and Discussion
As shown in Scheme 1, 4–6 with the molecular formula
[
1
C H O ·2C H N (CH ) ]·2Br [n = 5 (4), n = 8 (5), n =
2 (6); denoted Calix-IL-Br] were prepared by symmetric
44 56 4 4 6 2 2 n
1
Figure 1. (a) FTIR spectra of EuW10, 4, and 7. (b) H NMR spec-
tra of 4 and 7. (c) Thermogravimetric and differential thermal
–
1
modification of the lower rim of calix[4]arene with ILs with analysis of hybrid 7 with a scanning rate of 10 °Cmin . (d) Con-
different alkyl chains. Hybrid materials 7–9 were prepared tact-angle measurement of hybrid 7.
by ion exchange of 4–6 with EuW , and they were charac-
1
0
1
terized by FTIR and H NMR spectroscopy, thermogravi-
Table 1. FTIR W–O stretching bands of EuW10, 8, and 9.
metric analysis (TGA), and contact-angle measurements.
–
1
Compound
Stretch [cm ]
–W W–O –W
W=O
d
W–O
b
c
c
W–O –W
EuW10
945
935
940
840
836
837
779
781
776
696
710
714
8
9
1
The H NMR spectrum of 4 shows the signals of the
OCH , –NCH , and –NCH groups at δ = 3.95, 4.26, and
.73 ppm, respectively, which are shifted to δ = 4.03, 4.15,
–
3
2
2
3
and 3.83 ppm, respectively, in hybrid 7. Furthermore, the
signals of the hydrogen atoms on the imidazole ring are
shifted from δ = 7.69, 7.85, and 9.23 ppm in 4 to δ = 7.67,
7.76, and 9.07 ppm in 7, respectively. Such shifts and signal
broadening could be due to environmental changes re-
sulting from electrostatic interactions between 4 and the
EuW10 anions in 7.
1
Scheme 1. Schematic representation of the preparation process of
inorganic–organic hybrid materials 7–9.
Similarly, the H NMR spectra of hybrids 8 and 9 (Fig-
ure S2, Supporting Information) and the assignment of the
hydrogen atoms can be found in the Experimental Section,
As shown in Figure 1, the FTIR spectrum of EuW10 ex- and they are in good agreement with the expected struc-
hibits characteristic vibration bands of W=O , W–O –W, tures.
d
b
–
1
W–O –W, and W–O –W at 945, 840, 779, and 696 cm ,
TGA of 7 was performed in air between 25 and 900 °C
c
c
respectively, in which O is the terminal oxygen atom, O is at a scanning rate of 10 °Cmin–1 (Figure 1c). A distinct
d
b
the bridge oxygen atom of two octahedrons sharing a cor- multistep weight-loss process can be found in 7. The first
ner, and O is the bridge oxygen atom of two octahedrons weight loss of 2.26% in the 25–140 °C range can be attrib-
c
[
13]
sharing an edge.
In contrast, the FTIR spectrum of hy- uted to the loss of the crystallized water molecules. The
brid 7 displays the corresponding characteristic W–O vi- weight loss of 63.76% in the 140–640 °C range is due to
–
1
bration signals at 940, 836, 780, and 713 cm , respectively. stepwise decomposition of the C–C, C–H, and C–N bonds
[
14]
The shifts are due to electrostatic interactions between the through cleavage,
which indeed include the decomposi-
EuW10 anions and 4 in 7. The FTIR spectra of 8 and 9 tion of the alkyl chains, the calixarene, and the IL. Hybrids
and their characteristic W–O stretching bands are shown in 8 and 9 also show multistep weight-loss processes (Fig-
Figure S1 (Supporting Information) and are summarized in ure S3, Supporting Information), which can be explained in
Table 1.
a way similar to that of hybrid 7.
Eur. J. Inorg. Chem. 2014, 812–817
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SHORT COMMUNICATION
The photoluminescent spectra of hybrids 7–9 in Figure 2 function as extractants for DBT; therefore, no extra IL was
5
7
show five characteristic emission bands at 578 ( D Ǟ F ), added in this particular case. Additionally, the experimental
0
0
5
7
5
7
5
7
5
7
94 ( D Ǟ F ), 621 ( D Ǟ F ), 653 ( D Ǟ F ), 694 and results show that the catalyst can be recycled at least 10
0 1 0 2 0 3
5
7
05 nm ( D Ǟ F ), which correspond to the characteristic times with a slight decrease in the percentage of sulfur re-
0 4
5
7
3+ [15,16]
D Ǟ F (J = 0, 1, 2, 3, 4) transitions of Eu .
moved (100 to 95%). After each cycle, the catalyst was eas-
ily separated by filtration and washed with water and
chloroform. Then, it was reused in a second round. The
recycled catalyst was characterized by inductively coupled
0
J
1
plasma (ICP) and FTIR and H NMR spectroscopy (Fig-
ure S4, Supporting Information).
To disclose which component plays a role in the above
desulfurization results, contrast experiments were per-
formed, and the results are summarized in Table 2. Upon
using calix[4]arene for desulfurization, less than 5% sulfur
removal in 7 min was obtained (Table 2, Entry 1). Upon
using H O /EuW for desulfurization, almost no sulfur re-
Figure 2. Fluorescence spectra of hybrids 7–9.
2
2
10
moval in the absence of an IL was observed (Table 2, En-
try 2), which suggests that the oxidation does not take place
without an IL. Upon using 1 and 4 (Table 2, Entries 3 and
To know the hydrophobicity of hybrids 7–9, the contact
angles were measured. The experimental results show a su-
perhydrophobicity sequence of 9 (145.2°) Ͼ 8 (141.3°) Ͼ 7
4
) for the desulfurization in the presence of H O , 17.8 and
[
17,18]
2 2
(139.8°).
Given that hybrids 7–9 show superhydropho-
19.7% sulfur removal, respectively, was obtained at 70 °C
bicity, this property is advantageous for the formation of
hydrophobic/hydrophobic interactions and can be applied
in the ECODS process, especially in the extraction process.
This is because hydrophobic/hydrophobic interactions help
substrates such as DBT to go into the interface, where the
POM is oxidized by H O to form an active peroxo species
in 7 min. In contrast, deep desulfurization was achieved in
7
min by using hybrid 7 in the presence of H O as the
2
2
oxidant. Such a dramatic difference can be attributed to the
combination of the superhydrophobicity and the catalytic
desulfurization efficiency of hybrid 7.
2
2
that can oxidize DBT to DBTO . As a result, ECODS ex-
2
Table 2. Contrast experiments for the catalytic oxidative desulfur-
ization of DBT at 70 °C in 7 min.
periments with the use of 7–9 with H O as oxidant were
2
2
[a]
[
19]
performed.
Entry
Catalyst
H
2
O
2
/DBT
Sulfur removal (%)
To investigate the effect of temperature on the desulfur-
ization process, sulfur removal of DBT was performed at
different temperatures (Figure 3). Taking 7 as an example,
it shows 100% sulfur removal in 95, 35, 26, 15, and 7 min
at 30, 40, 50, 60, and 70 °C, respectively, in the presence of
H O . The oxidation product was demonstrated to be solely
1
2
3
4
5
calix[4]arene
3:1
3:1
3:1
3:1
3:1
Ͻ5
–
17.8
19.7
100
EuW10
1
4
7
2
2
[
a] Reaction conditions: H
2
O
2
(0.048 mL); model oil (5 mL), sulfur
DBTO (sulfone), which is indicative of the high efficiency
2
content S = 1000 ppm; H
2
2
O /DBT/7 = 60:20:1, 70 °C.
and selectivity of 7. In the case of 8 and 9, deep desulfuriza-
tion (100% sulfur removal) was achieved in 5.5 and 5 min,
respectively, at 70 °C.
Extension of the desulfurization time to 8 h did not help
sulfur removal for calix[4]arene, EuW , and 1 alone. In the
10
case of 4, although IL moieties were covalently grafted onto
the calix[4]arene, extension of the desulfurization time to
8
h caused only a slight increase in its ability to remove
sulfur (19.7 to 27.3%). It can be concluded from the above
contrast experiments that the synergistic effect of the ca-
lix[4]arene, the IL, and EuW10 play an important role in the
highly efficient desulfurization result.
To obtain the kinetic parameters for the extractive cata-
lytic oxidation desulfurization of DBT, experiments were
performed with a molar ratio of H O /DBT/7 = 60:20:1 at
2
2
7
0 °C. The percentage of sulfur removal and C are plotted
t
Figure 3. Times for 100% sulfur removal at different temperatures.
against the reaction time in Figure 4, in which C and C
are the initial DBT concentration and the DBT concentra-
tion at time t, respectively. Linear fit of the data revealed
0
t
Reaction conditions: H
2
O
O
2
(0.048 mL); model oil (5 mL), sulfur
2
/DBT/7 = 60:20:1.
content S = 1000 ppm; H
2
Notably, the addition of an IL is necessary to perform that the catalytic reaction exhibits pseudo-zero-order kinet-
2
the desulfurization in all of the ECODS systems reported ics for the desulfurization of DBT (R = 0.9931). The rate
so far. In the current case, ILs with different alkyl chains constant k of the oxidation reaction was determined to be
were covalently tethered onto the calix[4]arene, and they 173.29 ppmmin–1 on the basis of Equations (1) and (2). The
Eur. J. Inorg. Chem. 2014, 812–817
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SHORT COMMUNICATION
catalyst exhibits high catalytic efficiency for the oxidation for sulfur removal. Notably, if compared with other
of DBT to the corresponding sulfone with DBTO as the ECODS systems, the most important characteristic for 7–9
2
only product.
is that no extra addition of an IL is necessary. Moreover,
the heterogeneous catalytic systems can be reused 10 times
with only a slight decrease in reactivity. Therefore, inor-
ganic–organic hybrids 7–9 are useful heterogeneous cata-
lytic systems for deep desulfurization.
–
dC
t
=
k
(1)
(2)
dt
0 t
C – C = kt
Experimental Section
Chemical Materials: All chemicals were purchased from AlfaAesar
and were used without further purification. Acetone was distilled
from potassium permanganate. Diethyl ether was distilled from so-
dium and benzophenone. Acetonitrile and chloroform were dis-
tilled from calcium hydride. All reactions were performed under
nitrogen with dry solvents.
1
Measurements: H NMR spectra were recorded with a Bruker AV
400 NMR spectrometer at a resonance frequency of 400 MHz, and
the chemical shifts are given related to tetramethylsilane as an in-
ternal reference. FTIR spectra were recorded with a Bruker Vector
Figure 4. Sulfur removal of DBT and C
t
as functions of the reac-
tion time at 70 °C. H O /DBT/7 = 60:20:1.
2
2
22 infrared spectrometer by using the KBr pellet method. Mass
spectra were recorded with a Xevo G2 QT ESI mass spectrometer.
C, H, and N elemental analyses were performed with a Vario EL
cube from Elementar Analysis Systems. Thermogravimetric (TG)
and differential thermal analysis (DTA) were performed with a
TGA/DSC 1/1100 SF instrument from Mettler Toledo under N
To extend the applicability of inorganic–organic hybrid
, desulfurization of 4,6-DMDBT and BT (4,6-DMDBT =
,6-dimethyldibenzothiophene; BT = benzothiophene) with
7
4
7
as the catalyst, H O as the oxidant, and a molar ratio of
2
2
2
H O /substrate/7 = 60:20:1 at 70 °C was performed. The
–1
2
2
with a heating rate of 10 °Cmin . Fluorescence spectra were re-
experimental results showed 71.6 and 85.4% sulfur removal corded with a Cany Eclipse fluorescence analyzer.
of BT and 4,6-DMDBT, respectively, at 70 °C in 30 min,
and extension of the reaction time did not show a clear
increase in the desulfurization efficiency. This reactivity of
Synthesis: p-tert-Butylcalix[4]arene,[20] 1-(5-bromopentyl)-3-methyl-
imidazolium bromide (1), 1-(8-bromooctyl)-3-methylimidazolium
bromide (2), and 1-(12-bromododecyl)-3-methylimidazolium brom-
sulfur removal follows the order DBT Ͼ 4,6-DMDBT Ͼ ide (3) were prepared and characterized according to literature
BT, which is related to the electronic density of the S atoms methods.[ Compounds 4, 5, and 6 were synthesized by using a
and the steric hindrance of the substituent on the substrates. similar procedure, except for the use of ILs with different lengths of
21]
alkyl chains. The synthetic procedure for 4 is given as an example.
As is known, BT has the lowest electron density at the S
atom, as well as the lowest reactivity, whereas the difference
5
,11,17,23-Tetra-tert-butyl-25,27-dihydroxy-26,28-bis(3-methyl-
in electron density of 4,6-DMDBT and DBT is slight. imidazol-1-ium-1-ylpentyl)calix[4]arene Bromide (4): To a solution
Hence, the steric hindrance of the substrate plays a signifi- of p-tert-butylcalix[4]arene (4.95 g, 7.6 mmol) in freshly distilled
cant role in the different sulfur removal abilities of 4,6- acetone (60 mL) was added 1-(5-bromopentyl)-3-methylimid-
azolium bromide (1; 4.75 g, 15.3 mmol) and K
2
CO
3
(1.5 g,
DMDBT and DBT.
1
N
0.8 mmol), and the reaction mixture was heated at reflux under
In the three-phase catalytic system (oil phase, interface,
and solid phase), hydrophobic–hydrophobic interactions
help substrates such as DBT to go into the interface, where
EuW10 is oxidized by H O to form the active W–peroxo
for 6 d.[ After cooling the reaction mixture to room tempera-
22]
2
ture, the solution was concentrated under vacuum. A bright yellow
liquid was obtained as product 4. Yield: 6.77 g (80.2%). H NMR
1
2
2
(
400 MHz, [D
H, -C(CH ], 1.72 (m, 4 H, -CH
CH -), 3.73 (s, 6 H, -NCH ), 3.95 (t, 4 H, -OCH
NCH -), 4.56 (d, 8 H, Ar-CH -Ar), 6.90 (s, 2 H, Ar-OH), 7.14 (s,
8 H, ArH), 7.69 (s, 2 H, -CH NCHCHNC-), 7.85 (s, 2 H,
6
]DMSO): δ = 1.13 [s, 18 H, -C(CH
-), 2.01 (m, 8 H, -CH
-), 4.26 (t, 4 H,
3
)
3
], 1.19 [s, 18
species that can oxidize DBT to DBTO2.
3
)
3
2
2
-CH -
2
2
3
2
-
2
2
Conclusions
3
-
=
(
CNCHCHNCH
3364 (s), 2964 (s), 2870 (m), 1572 (m), 1485 (s), 1362 (m), 1302
m), 1202 (m), 1003 (m), 950 (w), 912 (w), 875 (m), 818 (w), 756
3 3
), 9.23 (s, 2 H, -NCHNCH ) ppm. IR (KBr): ν˜
To summarize, 4–6 were prepared by covalent tethering
of imidazole-based ILs with different alkyl chains onto
calix[4]arene. Ion exchange of 4–6 with EuW10 led to the
formation of hybrid materials 7–9. The contact angles of 7–
–1
– –
(w), 619 (m), 535 (w) cm . MS: m/z = 1191 [M + Br ] .
5
,11,17,23-Tetra-tert-butyl-25,27-dihydroxy-26,28-bis(3-methyl-
9
are Ͼ139°, which is indicative of the superhydrophobicity
1
imidazol-1-ium-1-yloctyl)calix[4]arene Bromide (5): Yield: 81%. H
NMR (400 MHz, [D ]DMSO): δ = 1.13 [s, 18 H, -(CH ], 1.18 [s,
8 H, -C(CH ], 1.42 [m, 16 H, -(CH -], 1.80 [m, 8 H,
(CH -], 3.86 (s, 6 H, -NCH ), 3.94 (t, 4 H, -OCH -), 4.15 (t, 4
of the hybrid materials, and this is advantageous for the
extraction of DBT through hydrophobic–hydrophobic in-
teractions. As a result, extractive catalytic oxidative de-
6
3 3
)
1
3
)
3
2 4
)
-
2
)
2
3
2
sulfurization (ECODS) by using 7–9 as catalysts in the pres- H, -NCH -), 4.17 (d, 8 H, -ArCH Ar-), 7.14 (s, 8 H, ArH), 7.71 (s,
2
2
ence of H O as the oxidant is highly efficient and selective 2 H, -CH
3
3
NCHCHNC-), 7.77 (s, 2 H, -CNCHCHNCH ), 9.17 (s,
2
2
Eur. J. Inorg. Chem. 2014, 812–817
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SHORT COMMUNICATION
2
H, -NCHNCH
3
) ppm. IR (KBr): ν˜ = 3405 (s), 2953 (s), 2863
2 2
two-necked flask, to which 30 wt.-% H O (0.048 mL, 0.47 mmol),
(
1
m), 1571 (m), 1486 (s), 1456 (w), 1362 (m), 1299 (m), 1198 (s), model oil (5 mL, 0.157 mmol), and 7 (54.8 mg, 0.0078 mmol;
–
1
170 (m), 1124 (m), 1023 (w), 871 (m), 755 (w), 622 (m) cm . MS:
2 2
57.3 mg for 8, 63.1 mg for 9) were added. The resulting H O /DBT/
–
2+
m/z = 517 [M – 2 Br ]
,11,17,23-Tetra-tert-butyl-25,27-dihydroxy-26,28-bis(3-methyl-
imidazol-1-ium-1-yldodecyl)calix[4]arene Bromide (6): Yield: 72.7%.
.
EuW10 molar ratio was 60:20:1. The reaction mixture was stirred
at 30, 40, 50, 60, or 70 °C. During the reaction, samples of the
upper layer of the model oil phase were periodically withdrawn and
analyzed by GC with a flame ionization detector (GC–FID); DBT
was identified by using reference standards. The content of DBT
was analyzed with an Agilent 7820A GC system with a 30 m 5%
phenylmethyl silicone capillary column with an inner diameter of
5
1
H NMR (400 MHz, [D
.18 [s, 18 H, -C(CH ], 1.26 [s, 28 H, -(CH
(CH -] 1.90 (m, 4 H, -CH -), 3.85 (s, 6 H, -NCH
H, -OCH -), 4.15 (t, 4 H, -NCH -), 4.17 (d, 8 H, -ArCH
s, 8 H, -ArH), 7.72 (s, 2 H, -CH NCHCHNC-), 7.78 (s, 2 H,
CH NCHCHNC-), 9.15 (s, 2 H, -NCHNCH ) ppm. IR (KBr): ν˜
3420 (s), 2925 (s), 2854 (s), 1682 (w), 1560 (m), 1486 (s), 1362
m), 1302 (m), 1199 (s), 1171 (m), 1124 (m), 1013 (w), 871 (m), 752
6
]DMSO): δ = 1.13 [s, 18 H, -C(CH
-], 1.78 [m, 8 H,
), 3.93 (t, 4
Ar-), 7.13
3 3
) ],
1
-
3
)
3
2 7
)
2
)
2
2
3
2
2
2
0.32 mm and 0.25 mm coating (HP-5). The analytical conditions
(
-
=
3
were as follows: injection port temperature 340 °C, detector tem-
perature 250 °C, oven temperature 70 °C, carrier gas ultrapure ni-
trogen, sample injection volume 1 μL.
3
3
(
(
–1
– 2+
w), 621 (m) cm . MS: m/z = 573 [M – 2 Br ]
.
Supporting Information (see footnote on the first page of this arti-
cle): FT-IR and H NMR spectra for 7–9, TG-DTA curves for 8,
1
Synthesis of Hybrid Materials: Hybrids 7–9 were prepared by ion
exchange of EuW10 with 4–6, respectively. Compounds 4–6 were
dissolved in distilled acetonitrile, and EuW10 was dissolved in
water. The two solutions were mixed, stirred at room temperature
for 24 h, and then washed with water to obtain 7–9.
9.
Acknowledgments
5
,11,17,23-Tetra-tert-butyl-25,27-dihydroxy-26,28-bis(3-methyl- This research was supported by the National Natural Science
1
imidazol-1-ium-1-ylpentyl)calix[4]arene–EuW10 (7): H NMR
400 MHz, [D ]DMSO): δ = 1.11 [s, 18 H, -C(CH ], 1.17 [s, 18
H, -C(CH ], 1.77 (m, 12 H, -CH -), 3.83 (s, 6 H, -NCH ), 4.03
t, 4 H, -OCH -), 4.15 (t, 4 H, -NCH -), 4.24 (d, 8 H, Ar-CH -Ar),
.09 (s, 8 H, ArH), 7.67 (s, 2 H, -CH NCHCHNC-), 7.76 (s, 2 H,
), 9.07 (s, 2 H, -NCHNCH ) ppm. IR (KBr): ν˜
3408 (s), 2956 (s), 2864 (m), 1572 (m), 1485 (s), 1362 (m), 1301
Foundation of China (21222104, 21076020), the Beijing Nova Pro-
gram (2009B12), and the Fundamental Research Funds for the
Central Universities (ZZ1227).
(
6
3 3
)
3
)
3
2
3
(
7
-
2
2
2
3
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3
3
=
(
5
w), 1202 (m), 943 (s), 839 (w), 780 (s), 710 (m), 623 (w), 584 (w),
–1
86 4 4 2
49 (w) cm . (C62H N O )4.5EuW10O36·10H O (7026.35): calcd.
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.81 (s, 6 H, -NCH ), 3.96 (t, 4 H, -OCH -), 4.12 (t, 4 H,
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–
1
124 (w), 935 (s), 836 (m), 781 (m), 710 (m), 626 (w) cm
36·7H O (7350.74): calcd. C 49.95, H 6.19,
N 3.43; found C 50.34, H 6.38, N 3.75. ICP: calcd. Eu 2.07, W
.
C
68
H
98
N
4
O
4
)4.5EuW10
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[
(
(
-
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1
(
–1
m), 940 (m), 837 (m), 776 (s), 714 (m), 627 (w) cm . (C76
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114
H -
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Published Online: January 17, 2014
Eur. J. Inorg. Chem. 2014, 812–817
817
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim