Novel and effective strategy of dual bis(trifluoromethylsulfonyl)imide imidazolium ionic liquid immobilized on periodic mesoporous organosilica for greener cycloaddition of carbon dioxide to epoxides

Article abstract of DOI:10.1039/C8NJ05273E

Novel periodic mesoporous organosilica supported nanocatalysts with different loading levels of a bis(trifluoromethylsulfonyl)imide anion-based dual imidazolium ionic liquid have been prepared and evaluated as efficient catalysts for the cycloaddition of CO₂ to epoxides. The as-fabricated PMO@IL-NTf₂(1.0) exhibited the best catalytic performance with excellent conversions (98-100%) and yields (96-99%) at 90 °C and 0.6 MPa for 0.5-1 h, based on a synergistic effect between the dual nucleophilic anion sites of the imidazolium ionic liquid and the hydroxyl group sites of periodic mesoporous organosilica. The excellent recyclability and operational simplicity make this protocol economic and environment-friendly.

Full text of DOI:10.1039/C8NJ05273E

View Article Online
View Journal
NJC
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: T. Jin , F. Dong, Y.
Liu and Y. Hu, New J. Chem., 2019, DOI: 10.1039/C8NJ05273E.
This is an Accepted Manuscript, which has been through the
Volume 40 Number
1 January 2016 Pages 1–846
Royal Society of Chemistry peer review process and has been
accepted for publication.
NJC
Accepted Manuscripts are published online shortly after
New Journal of Chemistry
www.rsc.org/njc
A journal for new directions in chemistry
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
ISSN 1144-0546
PAPER
Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
diarylethene-based metal–organic frameworks
rsc.li/njc

Please do not adjust margins
New Journal of Chemistry
Page 1 of 9
View Article Online
DOI: 10.1039/C8NJ05273E
1
2
3
4
5
New Journal of Chemistry
6
7
8
PAPER
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Novel and effective strategy of dual bis(trifluoromethylsulfonyl)
imide imidazolium ionic liquid immobilized on periodic
mesoporous organosilica‐mediated greener cycloaddition of
carbon dioxide to epoxides
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Jin Tan,a DongFang,b Yang Liua and Yu Lin Hu*a
www.rsc.org/
Novel periodic mesoporous organosilica supported nanocatalysts role for CO2 utilization. In general, the cycloaddition of CO2 to
with different loading levels of bis(trifluoromethylsulfonyl) epoxides can proceed under alkali metal or quaternary
imide anion‐based dual imidazolium ionic liquid have been ammonium salts catalysts.3,4 Unfortunately, these traditional
prepared and evaluated as efficient catalysts for the cycloaddition catalysts are not entirely satisfactory owning to the limitations
of CO2 to epoxides. The as‐fabricated PMO@IL‐NTf2(1.0) exhibited of corrosive wastes, tedious work‐up, and harsh reaction
the best catalytic performance with excellent conversions (98‐ conditions. In this regard plenty of representative catalytic
100%) and yields (96‐99%) at 90 °C, 0.6 MPa for 0.5‐1 h, based on a systems have been developed for the cycloaddition, including
synergistic effect between the dual nucleophilic anion sites of ZnI2/NEt3,5 Zn‐SBA‐15/KI,6 salen‐M (M
imidazolium ionic liquid and hydroxyl group sites of periodic organocatalysts,8 cobalt(III) complexes,9 MOFs,10 Bp‐Zn@MA,11
mesoporous organosilica. The excellent recyclability and amino
acid/KI,12 Fe3O4@carbon@poly(InIII‐carboxylate),13
operational simplicity making this protocol economical and MoO2(acac)2/TBAB,14 MCM‐41‐Imi/Br,15 MgO/TBAB/Bu4NBr,16
=
Co, Zn, Al),7
environmental‐friendly.
and others.17 However, despite the efficiency of these
protocols, most of them still suffer from problems including
the use of expensive reagents, unsatisfactory activity without
co‐catalysts, relatively rare availability and environmental
contamination. Therefore, the development of more
sustainable and efficient catalytic systems for conversion of
CO2 to cyclic carbonates continues to be a challenging goal.
Ionic liquids (ILs), as a class of environmental functional
materials, which have attracted much more attention due to
their structural and chemical diversities and have extensive
applications in fields of catalysis and chemical
transformations.18 In spite of their applications as catalysts
exhibit good catalytic activities for the conversion of CO2 to
cyclic carbonates,19 most of them have serious drawbacks in
terms of costly ILs separation and recyclability. Obviously, the
development of more environmentally benign and efficient
ionic liquid‐based heterogeneous catalysts are in great
demand. In recent years, immobilized homogenous ILs on
diverse solid support materials which could be both economic
and environmental‐friendly had attracted broad attention.20,21
The inherent advantages of heterogeneous catalysis are the
easily recovering and recycling catalysts, simple workup,
allowing low ILs loading in the transformations. Periodic
mesoporous organosilicas (PMOs) have attracted increasing
interests due to their large specific surface areas, tunable pore
sizes, high thermal and mechanical stabilities, and highly
ordered mesostructure properties, and thus have potential
applications in catalysis and chemical separation.22‐24 However,
their weak surface activity and hydrothermal stability limited
1. Introduction
Carbon dioxide (CO2) is the main greenhouse gas which caused
the global warming and climate change. Hence, a number of
strategies have been proposed to reduce the CO2 emission
such as CO2 capture, storage and chemical utilization.1,2
Among them, CO2 chemical utilization is regarded as the most
attractive one because CO2 has been sorted as a cheap,
nontoxic and abundant C1 building block for the preparation of
a wide range of valuable chemicals.2 Currently, numerous
strategies have been developed for CO2 chemical utilization,
and the cycloaddition of CO2 to epoxides is one of the most
attractive and sustainable crafts due to extensive applications
of the target products cyclic carbonates in fine chemistry.3
However, the activation of CO2 is difficult due to its inert
nature resulting from its high thermodynamic and kinetic
stability. The development of efficient catalytic systems for
conversion of CO2 into the desired cyclic carbonates is a crucial
aCollege of Materials and Chemical Engineering, Key laboratory of inorganic
nonmetallic crystalline and energy conversion materials, China Three Gorges
University, Yichang 443002, P. R. China. E‐mail: huyulin1982@163.com
bCollege of Chemistry and Environmental Engineering, Yancheng Teachers
University, Yancheng 224002, P. R. China
Electronic Supplementary Information (ESI) available: [details of any
supplementary information available should be included here]. See
DOI: 10.1039/x0xx00000x
†
This journal is © The Royal Society of Chemistry 20xx
New J. Chem., 2017, 00, 1‐3 | 1
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 2 of 9
View Article Online
DOI: 10.1039/C8NJ05273E
COMMUNICATION
Journal Name
1
2
3
4
5
6
7
8
9
suspension was aged at 90 °C for 24 h. The template was
removed from the as‐synthesized material by following
treatment with ethanol (250 mL) for 3 h under a static
condition and acetone (250 mL) at 50 °C under stirring for 6 h.
The solid material was thoroughly washed with deionized
water and acetone and dried under vacuum at 60 °C overnight.
2.3. Preparation of nanomaterials PMO@IL‐NTf2
their applications in chemical catalysis. It has been found that
their stabilization, dispersion and catalysis properties could be
greatly improved by the incorporation with organic or
inorganic moieties in the framework of PMOs.23 It is obvious
that ionic liquid‐modified periodic mesoporous organosilicas
would exhibit more outstanding catalytic performances by
combining the advantages of two materials. On the basis of
the aforementioned considerations, herein, we report on the
immobilization of a dual imidazolium ionic liquid onto periodic
mesoporous organosilica to design new and multifunctional
ionic liquid based nanomaterials catalysts. The supported
nanomaterials with different loading levels of bis(trifluorome
thylsulfonyl)imide anion‐based ionic liquid PMO@IL‐NTf2 were
studied their catalytic applications in the efficient and
environmental‐friendly the cycloaddition of CO2 to epoxides
under mild conditions (Scheme 1). Furthermore, the
recyclability and reusability of the nanocatalyst were also
discussed.
PMO@IL‐NTf2 were prepared according to previously
described processes25 as shown in Scheme S1. Sodium
ethoxide (0.4 mol) and imidazole (0.4 mol) were dissolved in
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
o
ethanol (400 mL) and then stirred at 70 C for 6 h, then 1,4‐
dichlorobutane (0.2 mol) was added to the mixture with
o
continuous stirring at 60 C for 2 h. After that, the suspension
was filtrated and the filtrate was evaporated to 100 mL, the
resultant solid was collected by filtration and then washed
with ethanol‐water to give
1. Next, (3‐Chloropropyl)
triethoxysilane (0.3 mol), (0.15 mol) and toluene (150 mL)
1
were mixed in a reaction vessel, and the resulting mixture was
o
stirred at 100 C for 24 h. The solvent was evaporated and
washed with ethanol dried under vacuum to give 2. 2 (0.05
mol), CH3CN (100 mL), and LiNTf2 (0.1 mol) were stirred at 60
°C for 24 h. Upon completion of reaction, the suspension was
filtrated and the filtrate was evaporated using rotary‐
evaporator to give ionic liquid
synthesized according to the mass ratio of 1.0 g PMO: x g IL‐
NTf2 ( ). In a typical preparation process: x g of ILanion was
3 IL‐NTf2. PMO@IL‐NTf2(x) was
3
added to dry toluene (100 mL) at room temperature. Then
PMO (1.0 g) was added to the solution. Thereafter, the mixture
was continuously refluxed for 24 h. Finally, the mixture was
filtrated, and the resulting solid was washed with EtOAc (3 ×
10 mL) and dried under vacuum at 60 °C for 8 h to afford the
nanomaterials PMO@IL‐NTf2(x).
Scheme 1 Catalytic cycloaddition of CO2 to epoxides with
PMO@IL‐NTf2.
2. Experimental
2.1. Reagents and apparatus
2.4. Catalystic cycloaddition of CO2 to epoxides
Reagents and solvents were of analytical grade and Pluronic
In a representative experiment, epoxide (0.1 mol) and
PMO@IL‐NTf2 (0.2 g) were introduced into a stainless steel
high pressure reactor without addition of any co‐catalyst and
solvent. The reactor was sealed and flushed 3 times with CO2
at room temperature. The pressure was then adjusted to 0.6
MPa and the reaction mixture was stirred at 90 °C for the
desired time. After the completion of the reaction, monitored
by GC, the method for typical analysis by setting the conditions
such as injection temperature 280 °C, detector temperature
280 °C, oven temperature program 60 °C, holding initial
temperature for 1 min then ramp rate 15 °C/min to 260 °C,
and holding at final temperature for 4 minutes. Epoxide and
cyclic carbonate amounts were obtained from their respective
GC integration areas in the presence of the internal standard.
The pressure of reactor was fall down to a presetting value,
then the excess of CO2 was vented. The resulting mixture was
distilled under vacuum to afford the desired pure product.
Fresh substrates were then recharged to the recovered
catalyst and then recycled at the same reaction conditions.
The products were identified by comparing their physical and
GC spectra with those of commercial materials.
P123
(EO20PO70EO20,
MW
=
5800)
and
1,2‐
bis(triethoxysilyl)ethane were obtained by Sigma‐Aldrich. The
chemical structures of catalysts were characterized by FT‐IR
spectra (Nicolet Nexus 470) spectrometer. The Powder X‐ray
diffraction (XRD) analysis was carried out on a Bruker D8
Advance diffractometer. X‐ray photoelectron spectroscopy
(XPS) analysis was recorded on a SPECS HSA3500 plus
spectrometer. Scanning electron microscopy (SEM) analysis
were recorded on a JSM‐7500F instrument. The element
composition of catalysts were characterized by Hitachi S‐4800
field emission scanning electron microscope accompanied by
Energy dispersive X‐ray (EDX) spectrometry. UV‐Vis
measurement was determined by Shimadzu UV‐2450
spectrometer. N2 adsorption‐desorption measurements were
measured on a Micromeritics‐2010 apparatus. Melting points
were measured by an electro‐thermal IA 9100 apparatus. Gas
chromatograph (GC) experiments were performed on a
Shimadzu GC‐2010plus chromatograph equipped with a FID
and a DB‐wax capillary column (30 m × 0.53 mm × 1.0 μm). 1H
NMR spectra were recorded in Bruker 400 MHz spectrometer.
Elemental analysis was carried out on a Vario EL Micro cube
Elemental Analyzer.
2.5. Spectroscopic data for products
4‐Methyl‐1,3‐dioxolan‐2‐one (Table 2, entry 1): H NMR: δ =
1
2.2. Preparation of periodic mesoporous organosilica (PMO)
PMO was prepared according to the known procedures.24 In a
typical synthesis, Pluronic P123 (2.5 g) was dissolved in HCl
solution (2N, 80 mL) with stirring at room temperature.
Afterwards, 1,2‐bis(triethoxysilyl)ethane (2.95 g) was added
and the resultant solution was stirred at 35 °C for 3 h. Then the
1.41 (dd, CH3, 3H), 3.99 (t, CH, 1H), 4.54 (t, CH, 1H), 4.91 (t, CH,
1H). Anal. Calcd. for C4H6O3: C, 47.02; H, 5.89; O, 46.97. Found:
C, 47.06; H, 5.92; O, 47.02.
1
1,3‐Dioxolan‐2‐one (Table 2, entry 2): H NMR: δ = 4.54 (s,
CH2CH2, 4H). Anal. Calcd. for C3H4O3: C, 40.89; H, 4.55; O,
54.48. Found: C, 40.92; H, 4.58; O, 54.50.
2 |New J. Chem., 2017, 00, 1‐3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 3 of 9
View Article Online
DOI: 10.1039/C8NJ05273E
Journal Name
COMMUNICATION
1
2
3
4
5
6
7
8
9
4‐(Hydroxymethyl)‐1,3‐dioxolan‐2‐one (Table 2, entry 3): 1H
NMR: δ = 3.78 (t, CH2, 2H), 3.91 (t, OH, 1H), 4.12 (dd, CH2, 2H),
4.98 (m, CH, 1H). Anal. Calcd. for C4H6O4: C, 40.65; H, 5.10; O,
54.15. Found: C, 40.68; H, 5.12; O, 54.19.
indicated that the highly ordered mesoporous structure of
these nanomaterials were preserved, even though the ionic
liquids species have been introduced in the framework of
PMO.23 The absence of obvious characteristic peaks of ionic
liquids species in the XRD patterns suggests that ionic liquids
4‐(Methoxymethyl)‐1,3‐dioxolan‐2‐one (Table 2, entry 4): 1H
NMR: δ = 3.34 (s, OCH3, 3H), 3.73 (dd, OCH2, 2H), 4.07 (dd, CH2,
2H), 4.95 (m, CH, 1H). Anal. Calcd. for C5H8O4: C, 45.42; H, 6.07;
O, 48.42. Found: C, 45.46; H, 6.10; O, 48.44.
species were well-dispersed on the surface and in the
mesopore channels of periodic mesoporous organosilica,
which also showed that the crystal structure of PMO was
maintained and intact during the synthetic process.
4‐(Chloromethyl)‐1,3‐dioxolan‐2‐one (Table 2, entry 5): 1H
NMR: δ = 3.76 (dd, CH2, 2H), 4.35 (dd, CH2, 1H), 4.63 (dd, CH2,
1H), 4.96 (m, CH2, 1H). Anal. Calcd. for C4H5ClO3: C, 35.15; H,
3.66; Cl, 25.96; O, 35.13. Found: C, 35.19; H, 3.69; Cl, 25.97; O,
35.15.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
4‐(Trifluoromethyl)‐1,3‐dioxolan‐2‐one (Table 2, entry 6): 1H
NMR: δ = 4.08‐4.12 (dd, CH2, 2H), 5.06 (t, CH, 1H). Anal. Calcd.
for C4H3F3O3: C, 30.76; H, 1.91; F, 36.48; O, 30.75. Found: C,
30.78; H, 1.94; F, 36.52; O, 30.76.
1
4‐Phenyl‐1,3‐dioxolan‐2‐one (Table 2, entry 7): H NMR: δ =
4.34 (t, CH2, 1H), 4.76 (t, CH2, 1H), 5.65 (t, CH2, 1H), 7.31‐7.46
(m, Ar‐H, 5H). Anal. Calcd. for C9H8O3: C, 65.82; H, 4.88; O,
29.21. Found: C, 65.85; H, 4.91; O, 29.24.
3. Results and discussion
Fig. 2 PXRD patterns of PMO (a), PMO@IL‐NTf2(0.5) (b),
PMO@IL‐NTf2(1.0) (c), and PMO@IL‐NTf2(1.5) (d).
The as‐synthesized nanomaterials PMO@IL‐NTf2 are
characterized using FT‐IR, XRD, UV–vis, SEM, N2 physisorption,
XPS, and TG/DSC. Fig. 1 illustrates FT‐IR spectra of the
nanomaterials. The characteristic peaks at about 1562 cm‐1,
1635 cm‐1 and 3078 cm‐1 could be attributed to C=C, C=N and
C–H stretching vibration of imidazolium ring.18 The absorption
peaks at about 2865 cm‐1, 1294 cm‐1, and 731 cm‐1 could be
assigned to the stretching vibration of methylene chain, while
the bands at about 1085 cm−1 and 478 cm−1 were ascribed to
the stretching vibration of Si–O–Si. The characteristic bands at
about 3452 cm‐1 and 965 cm−1 were belonged to the stretching
vibration of OH and Si–OH, respectively. The peaks observed at
1357 cm−1, 1192 cm−1, 1136 cm−1, 1054 cm−1 are related to
vibrational modes of NTf2 anion.24
SEM images of as‐synthesized nanomaterials are shown in
Fig. 3. Fig. 3a clearly showed the well‐ordered arrays of the
mesoporous, which was typical morphology of periodic
mesoporous organosilica materials.22 It was clearly observed
that the morphologies of the immobilized nanomaterials were
agglomerations of small spherical with uniform nanometre
sized particles.
The elemental composition of as‐synthesized nanomaterials
by EDX were shown in Fig. 4 and (Table S1, ESI). It was obvious
that the silicon and oxygen content of both PMO and PMO@IL‐
NTf2 gradually decreased. Simultaneously, compared with
PMO, the resultant PMO@IL‐NTf2 materials showed that the
carbon and fluorine content significantly increased, this was
because the grafted‐IL‐NTf2 precursor has more carbon and
fluorine than pristine PMO. The amount of carbon species in
PMO, PMO@IL‐NTf2(0.5), PMO@IL‐NTf2(1.0), and PMO@IL‐
NTf2(1.5) were 1.79%, 6.31%, 13.71% and 17.95%, respectively.
These results confirmed the successful immobilization of ionic
liquids species on the PMO.
Fig. 1 FT‐IR spectras of PMO (a), PMO@IL‐NTf2(0.5) (b),
PMO@IL‐NTf2(1.0) (c), and PMO@IL‐NTf2(1.5) (d).
Fig. 2 illustrates the PXRD patterns of the prepared
nanomaterials. The three typical diffraction peaks of catalysts
PMO@IL‐NTf2 were observed at 2θ = 2.1°, 3.2°, and 4.1°, which
can be assigned to the (100), (110) and (200) reflections of
ordered mesoporous structure. Besides, XRD peak intensity of
PMO‐IL‐anion were similar to the pattern of PMO, apart from
some slight variations in the Bragg intensities. These results
Fig. 3 SEM images of PMO (a), PMO@IL‐NTf2(0.5) (b), PMO@IL‐
NTf2(1.0) (c), and PMO@IL‐NTf2(1.5) (d), six times recycled
PMO@IL‐NTf2(1.0) (e).
This journal is © The Royal Society of Chemistry 20xx
New J. Chem., 2017, 00, 1‐3 | 3
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 4 of 9
View Article Online
DOI: 10.1039/C8NJ05273E
COMMUNICATION
Journal Name
1
2
3
4
the structure of the nanocatalyst, which were consistent with
the FT‐IR, PXRD and EDX analysis.
To examine the catalytic activity of PMO@IL‐NTf2,
cycloaddition of CO2 and propylene oxide to propylene
carbonate was chosen as a model reaction. Initially, the
catalytic activity with different ionic liquid loading levels of
nanocatalysts PMO@IL‐NTf2(0.5), PMO@IL‐NTf2(1.0), and
PMO@IL‐NTf2(1.5) have been studied (Table 1, entries 1‐3). As
results show, PMO@IL‐NTf2(1.0) was the highly effective
catalyst, affording a conversion of 99% with product yield of
99% (Table 1, entry 2), which presented high TON and TOF
values of 980 and 980 h−1. These results indicated that
PMO@IL‐NTf2(1.0) has the highest catalytic activity with
perfect selectivity of 100% for the cycloaddition. The active
sites of the nanocatalyst is sufficient for the reaction, may be
due to the synergistic effect between the basic sites of the
ionic liquid and periodic mesoporous organosilica. The amount
of catalyst also influenced the performance on the
cycloaddition. With increasing the amount of the nanocatalyst
up to 0.2 g, a dominant increase in the conversion and product
yield were observed (Table 1, entries 2, 6‐8). Meanwhile, an
enhancement of the TON and TOF were also obtained. While
further increased to 0.25 g, it does not significantly improve
the propylene oxide conversion and product yield (Table 1,
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Fig. 4 EDX images of PMO (a), PMO@IL‐NTf2(0.5) (b), PMO@IL‐
NTf2(1.0) (c), and PMO@IL‐NTf2(1.5) (d).
Fig. S1 (ESI) showed the diffuse reflectance UV–Vis spectra
of the prepared nanomaterials. A broad absorption peak could
be observed distinctly in the region of 220–240 nm, which
were attributed to the characteristic absorption properties of
periodic mesoporous organosilica.22 TG analysis was conducted
to investigate the thermal stability of nanomaterials (Fig. S2,
ESI). The small weight loss before 100 °C resulted from the
desorption of adsorbed water onto sample surface. It can
clearly see that there existed drastic weight loss about 44.6 %
for PMO@IL‐NTf2(0.5), 46.1 % for PMO@IL‐NTf2(1.0) and 46.8
% for PMO@IL‐NTf2(1.5) at a temperature between 300 and
610 °C, which was attributed to the breakdown of the organic
moieties. From the curves depicted, it demonstrated that the
nanocatalysts PMO@IL‐NTf2 are thermally stable below about
300 °C. Fig. S3 (ESI) showed the isotherms and pore size
distribution of the prepared nanocatalyst PMO@IL‐NTf2(1.0). It
can be observed that the samples exhibited a type IV isotherm
which was characteristic of highly ordered mesoporous
material.23 No obvious change in average pore size is observed,
and the surface area and pore volume gradually decreased
after immobilization of ionic liquid, which was due to the
anchoring of ionic liquid species in the pore walls. The pore
volumes of the nanomaterials displayed the order: PMO >
PMO@IL‐NTf2(1.0). It is clear that PMO@IL‐NTf2(1.0) has a BET
surface area of 316.14 m2 g‐1 and a total pore volume of 0.51
cm3 g‐1. The pore size distribution confirms that well defined
porous with pore size distribution of 5.57 nm is present in this
nanomaterial (Table S2, ESI). These results revealed the well‐
ordered mesostructure for the nanocatalyst. XPS investigation
was performed and shown in Fig. S4 (ESI), the nanocatalyst
PMO@IL‐NTf2(1.0) was composed of C, N, O, S, Si, and F, and
the peaks corresponding to C1s, N1s, O1s, S2p, Si2p, and F1s
appeared at 284.6 eV, 401.6 eV, 532.7 eV, 169.4 eV, 103.5 eV,
and 686.9 eV, respectively.21,23 The XPS results further verified
entry 9). This may be due to the fact that when the catalyst
amount increase up to a certain concentration, there exists
conflict between the rise in the catalytic active sites and the
decline in the heat and mass transfer.17 Apparently, it is a
promising result that PMO@IL‐NTf2(1.0) exhibited high
catalytic activity at low catalyst amount of 0.2 g in the catalytic
progress. For comparison, the cycloaddition was also
performed using PMO alone and bulk IL IL‐NTf2 as catalyst
(Table 1, entries 4 and 5). Using PMO alone, only 26% product
yield was afforded (Table 1, entry 5), while that of using bulk IL
as the catalyst afforded the desired product in moderate yield
of 81%, and the TON and TOF decreased to 38 and 115 h−1,
respectively (Table 1, entry 4). Therefore, PMO@IL‐NTf2(1.0) is
the suitable nanocatalyst for the cycloaddition.
Table 1 Catalyst screening for the catalytic cycloaddition of CO2 to
propylene oxide a
Yiel
d
(%)c
TOF (h‐
Entr
y
Amoun
t (g)
Tim
e (h)
Conversio
n (%)b
1 d
Catalyst
)
/TONe
PMO@IL
‐
NTf2(0.5)
213/42
6
1
0.2
2
89
87
PMO@IL
‐
NTf2(1.0)
980/98
0
2
3
0.2
0.2
1
1
99
99
99
706/70
6
PMO@IL
‐
>99
4 |New J. Chem., 2017, 00, 1‐3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 5 of 9
View Article Online
DOI: 10.1039/C8NJ05273E
Journal Name
COMMUNICATION
1
2
3
NTf2(1.5)
4
5
6
7
8
9
4
5
6
IL‐NTf2
PMO
‐
0.2
0.2
‐
3
5
84
30
0
81
26
0
38/115
‐/‐
24
‐/‐
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
PMO@IL
‐
NTf2(1.0)
346/51
9
7
8
9
0.1
1.5
1
87
94
86
94
99
Fig. 5 Effect of reaction temperature on the cycloaddition.
Reaction conditions: propylene oxide (0.1 mol), PMO@IL‐
NTf2(1.0) (0.2 g), CO2 (0.6 MPa) were stirred at different
temperature for 1 h.
PMO@IL
‐
NTf2(1.0)
765/76
5
0.15
0.25
PMO@IL
‐
NTf2(1.0)
867/86
7
1
>99
a
The reactions were carried out with propylene oxide (0.1 mol),
CO2 (0.6 MPa) with catalyst at 90 °C. b Isolated conversion. c Isolated
yield. dmole of produced propylene carbonate per mol of NTf2‐
containing catalyst per hour. econverted mole of propylene
oxide/mole of NTf2‐containing catalyst.
The next investigations were conducted with the reaction
parameters such as reaction temperature and CO2 pressure. It can
be seen that an increase in reaction temperature up to 90 °C led to
a remarkable increase of conversion and yield. However, when the
reaction temperature is further increased to 110 °C, the product
yield will decline to 95% (Fig. 5), a small amount of byproducts of
acetone and propylene glycol were formed, which were detected by
GC analysis, mostly due to the side reactions of propylene oxide
isomerization and hydrolysis of propylene oxide at overly high
temperatures. The influence of CO2 pressure on the cycloaddition
were also investigated (Fig. 6). The conversion and yield could be
enhanced as CO2 pressure increases from 0.2 MPa to 0.6 MPa, with
60ꢀ% increase in conversion and 63ꢀ% increase in yield being
probed. High CO2 pressure could enhance the concentration of CO2
and facilitate the interaction between CO2 and epoxide, thus
favouring the cyclic carbonate formation. However, the yield and
conversion were obviously decreased with further increasing CO2
pressure beyond 0.6 MPa. A possible explanation was that the
exceedingly high CO2 pressure may block the interaction between
propylene epoxide and the catalyst, and would reduce the
concentration of propylene epoxide in the bottom catalyst phase.
More propylene epoxide was extracted into CO2 phase leading to
the decreased conversion and yield.17
Fig. 6 Effect of CO2 pressure on the cycloaddition. Reaction
conditions: propylene oxide (0.1 mol), PMO@IL‐NTf2(1.0) (0.2
g) were stirred in different CO2 pressure at 90 °C for 1 h.
To further gain insight, the recyclability of PMO@IL‐NTf2(1.0) in
the cycloaddition of CO2 to propylene oxide was investigated (Fig.
7). PMO@IL‐NTf2(1.0) was easily recovered by a simple filtration
and after being washed with dichloromethane and dried, could be
reused directly for six successive runs with negligible loss in the
catalytic activity, which confirms the advantageous excellent
catalytic activity, stability and reusability of the nanocatalyst. SEM
results of the reused PMO@IL‐NTf2(1.0) after six runs indicated that
the morphology and highly ordered nanostructure of the catalysts
could be maintained during the course of the cycloaddition (Fig.
3e). FT‐IR and XRD analysis of the reused nanocatalyst PMO@IL‐
NTf2(1.0) after six runs were very similar to those of the fresh
nanocatalyst, indicating that no obvious change in the characteristic
structures of the nanocatalyst happened during the cycloaddition
(Fig. S5 and S6, ESI). In addition, the elemental analysis did not
show obvious changes in the elemental distribution and content of
the nanocatalyst (Tables S3, ESI). These results confirmed that the
designed nanocatalyst was featured by the outstanding stability and
durablility during the catalytic process, and almost no leaching of
the nanocatalyst species occurred.
This journal is © The Royal Society of Chemistry 20xx
New J. Chem., 2017, 00, 1‐3 | 5
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 6 of 9
View Article Online
DOI: 10.1039/C8NJ05273E
COMMUNICATION
Journal Name
1
2
3
4
5
6
7
8
6
7
1
1
98
98
97
96
970/970
970/970
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
a Reaction conditions: epoxide (0.1 mol), PMO@IL‐NTf2(1.0) (0.2 g),
CO2 (0.6 MPa), were stirred at 90 °C. b Isolated conversion. c Isolated
yield.
Fig. 7 Recyclability of the nanocatalyst PMO@IL‐NTf2(1.0).
Encouraged by the above results, we evaluated the catalytic
activities of PMO@IL‐NTf2(1.0) in this heterogeneous cycloaddition
of CO2 to different epoxides under the optimized conditions, and
On the basis of the above results and the analogous mechanisms
the results are listed in Table 2. All terminal epoxides could be discussed in the literatures,8,13‐15,19,20c
a
possible catalytic
smoothly converted and afforded the desired cyclic carbonates in mechanism for the cycloaddition was outlined in Scheme 2. It was
high to excellent yields in short reaction time. To our delight, both found that the presence of hydrogen bond donors were beneficial
electron‐deficient
and
electron‐rich
epoxides
delivered to the activation of epoxides and amine basic sites are effective for
corresponding cyclic carbonates in 96‐99% isolated yields (Table S2, CO2 adsorption and activation,8,27 the presence of Si‐OH active sites
entries 1‐7). High values of TON and TOF were obtained for this of PMO initially facilitates the efficient epoxide activation through
cycloaddition and amounts to be ~990 and ~1980 h−1, respectively. the coordination of hydrogen bonding of the hydroxyl group on
These results show high efficiency and versatility of the designed PMO surface with oxygen atom of epoxide to form intermediate I,
nanocatalyst in all cases.
together with the adsorption and activation of CO2 by the ternary
amine of imidazolium ring to form carbonate species, followed by
the nucleophilic attack of NTf2 anion sites on the less sterically
hindered carbon atom of epoxide to form a intermediate II.
Subsequently, intermediate II reacts with CO2 by a nucleophilic
attack to form intermediate III. Spontaneous formation of the cyclic
carbonate via an intramolecular substitution cyclic step to
regenerate the nanocatalyst. This indicates that the active sites of
nanocatalyst enhancing the cycloaddition cycle due to the
synergistic effects between the dual basic sites of imidazolium ionic
liquid and hydroxyl group sites of periodic mesoporous organosilica,
which is crucial for achieving fast reaction rate and excellent yields.
a
Table 2 Catalytic cycloaddition of various epoxides with CO2
Entr
y
Epoxid
e
Produc
t
Tim
Conversio
n (%)b
Yiel
d
(%)c
TOF (h‐
1)/TON
e (h)
1
2
1
1
99
99
99
980/980
990/990
100
1980/99
0
3
4
5
0.5
1
100
99
99
98
99
980/980
1980/99
0
0.5
100
Scheme 2 Possible mechanism for cycloaddition of CO2 to
epoxides.
6 |New J. Chem., 2017, 00, 1‐3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 7 of 9
View Article Online
DOI: 10.1039/C8NJ05273E
Journal Name
COMMUNICATION
1
2
3
4
5
In order to examine the efficiency and capability of the present Furthermore, this heterogeneous catalytic route shows excellent
protocol, we compared the catalytic activities of PMO@IL‐NTf2(1.0) reusability and could be reused for six runs with negligible loss of
in the cycloaddition of CO2 to styrene oxide with other reported activity. The advantages of the present method are high catalytic
catalysts (Table 3). Obviously, our catalytic system show promising activity, easy work‐up, excellent reusability, green and
features in terms of high activity and efficiency, high to excellent environmentally benign.
6
7
8
9
yields, and mild reaction conditions. From the results, we are able Conflicts of interest
to establish that PMO@IL‐NTf2(1.0) is a type of practical and
suitable heterogeneous nanocatalyst for the cycloaddition.
There are no conflicts of interest to declare.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Acknowledgements
This work was supported by National Natural Science Foundation
of China (no. 21506115).
Table 3 Comparison of the catalytic efficiency of the present system
as compared to other catalysts
Time
(h)
Yield
(%)a
Entry
Catalyst
Conditions
Reference
6
Notes and references
1.0 MPa,
80 °C
1
2
3
4
5
6
7
8
9
Zn‐SBA‐15/KI
2PhCH2TMG
9
20
12
4
84
90
84
97
93
81
88
96
96
1 (a) R. A. Agarwal and N. K. Gupta, Coordin. Chem. Rev.,
2017, 332, 100‐121; (b) R. Balasubramanian and S.
Chowdhury, J. Mater. Chem. A, 2015, 3, 21968‐21989.
2 (a) N. von der Assen, P. Voll, M. Peters and A. Bardow,
Chem. Soc. Rev., 2014, 43, 7982‐7994; (b) A. Danon, P. C.
Stair and E. Weitz, J. Phys. Chem. C, 2011, 115, 11540–
11549.
3 Y. Wang and D. J. Darensbourg, Coordin. Chem. Rev.,
2018, 372, 85‐100.
4 L. Wang, P. Li, X. Jin, J. Zhang, H. He, S. Zhang, J. CO2 Util.,
2015, 10, 113‐119.
5 J. Ma, L. Lu, Q. Mei, Q. Zhu, J. Hu and B. Han,
ChemCatChem, 2017, 9, 4090‐4097.
6 M. Liu, K. Gao, L. Liang, J. Sun, L. Sheng and M. Arai, Catal.
Sci. Technol., 2016, , 6406‐6416.
7 T. T. Wang, Y. Xie and W. Q. Deng, J. Phys. Chem.
A, 2014, 118, 9239‐9243.
8 (a) R. K. Tak, P. Patel, S. Subramanian, R. I. Kureshy and N.
H. Khan, ACS Sustainable Chem. Eng., 2018, 6, 11200‐
11205; (b) E M. Mayaa, E. Rangel‐Rangela, U. Díazc and
M. Iglesias, J. CO2 Util., 2018, 25, 170‐179; (c) X. F. Liu, Q.
W. Song, S. Zhang and L. N. He, Catal. Today, 2016, 263
69‐74.
9 X. Jiang, F. Gou, F. Chen and H. Jing, Green Chem., 2016,
18, 3567‐3576.
10 (a) Y. H. Han, Z. Y. Zhou, C. B. Tian and S. W. Du, Green
Chem., 2016, 18, 4086‐4091; (b) P. Rani and R. Srivastava,
New J. Chem., 2017, 41, 8166‐8177; (c) P. Z. Li, X. J.
Wang, J. Liu, J. S. Lim, R. Zou and Y. Zhao, J. Am. Chem.
Soc., 2016, 138, 2142‐2145; (d) V. Sharma, D. De, R. Saha,
R. Das, P. K. Chattaraj and P. K. Bharadwaj, Chem.
Commun., 2017, 53, 13371‐13374.
11 J. Chen, H. Li, M. Zhong and Q. Yang, Green Chem., 2016,
18, 6493‐6500.
12 K. R. Roshan, A. C. Kathalikkattil, J. Tharun, D. W. Kim, Y.
S. Won and D. W Park, Dalton Trans., 2014, 43, 2023‐
2031.
13 Q. An, Z. Li, R. Graff, J. Guo, H. Gao and C. Wang, ACS
Appl. Mater. Interfaces, 2015, 7, 4969‐4978.
14 F. Chen, T. Dong, T. Xu, X. Li and C. Hu, Green Chem., 2011,
13, 2518‐2524.
15 J. Nelson and A. F. Adam, Appl. Catal. B: Environ., 2013,
136‐137, 150‐159.
0.7 MPa,
100 °C
8b
DMAP‐Zr‐BDC‐
MOF
1.0 MPa,
100 °C
10b
MCM‐41‐
Imi/Br
3.0 MPa,
100 °C
15
ZrCl4∙(OEt2)2‐
cis/TBAB
1.0 MPa,
60 °C
18
2
17a
6
polyILs@MIL‐
101
0.1 MPa,
70 °C
17b
polymer
supported ILs
0.8 MPa,
100 °C
8
20c
,
2.0 MPa,
120 °C
Ch‐ILBr
5
21b
PMO@IL‐
NTf2(1.0)
0.6 MPa,
90 °C
1
This work
a Isolated yield.
4. Conclusions
In conclusion, a type of dual imidazolium ionic liquid‐based
multifunctional periodic mesoporous organosilica nanomaterials
PMO@IL‐NTf2 were synthesized, characterized and used as novel
heterogeneous catalysts for the cycloaddition of CO2 to epoxides.
The presence of synergistic effects between the dual basic sites of
ionic liquid and hydroxyl group sites of periodic mesoporous
organosilica in the nanomaterials makes them suitable as active
catalysts for the cycloaddition. The catalytic research demonstrated
that the multifunctional cooperative nanocatalyst PMO@IL‐
NTf2(1.0) exhibited higher activity than other catalysts in this
reaction. The present method provides an operationally simple,
highly efficient, and environmentally benign alternative for the
cycloaddition without addition of any co‐catalyst and solvent.
16 A. H. Chowdhury, P. Bhanja, N. Salam, A. Bhaumik, S. M.
Islam, Mol. Catal., 2018, 450, 46‐54.
17 (a) M. J. Kelly, A. Barthel, C. Maheu, O. Sodpiban, F. B.
Dega, S. V. C. Vummaleti, E. Abou‐Hamad, J. D. A.
Pelletier, L. Cavallo, V. D’Elia, J. M. Basset, J. CO2 Util.,
2017, 20, 243‐252; (b) M. Ding and H. L. Jiang, ACS
Catal., 2018,
8
, 3194‐3201; (c) R. Srivastava, D. Srinivas
This journal is © The Royal Society of Chemistry 20xx
New J. Chem., 2017, 00, 1‐3 | 7
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 8 of 9
View Article Online
DOI: 10.1039/C8NJ05273E
COMMUNICATION
and P. Ratnasamy, J. Catal., 2005, 233, 1‐15; (d) A. C.
Journal Name
1
2
3
4
5
6
7
8
M. Isaacs, J. Honores, D. Quezada, E. Landaeta, R.
Ormazábal‐Toledo, J. CO2 Util., 2016, 16, 114‐120.
Kathalikkattil, D. W. Kim, J. Tharun, H. G. Soek, R. Roshan
and D. W. Park, Green Chem., 2014, 16, 1607‐1616.
18 (a) M. G. Cowan, D. L. Gin and R. D. Noble, Acc. Chem.
Res., 2016, 49, 724‐732; (b) S. K. Kabra, M. Huuhtanen, R. L.
Keiski and G. D. Yadav, React. Chem. Eng., 2016, 1, 330‐339;
(c) A. H. Jadhav, D. Prasad, H. S. Jadhav, B. M. Nagaraja
and J. G. Seo, Energy, 2018, 160, 635-647; (d) A. H. Jadhav
and H. Kim, Chem. Eng. J., 2012, 200‐202, 264‐274.
9
19 (a) L. Ji, Z. Luo, Y. Zhang, R. Wang, Y. Ji, F. Xia, G. Gao,
Mol. Catal., 2018, 446, 124‐130; (b) Q. He, J. W. O'Brien, K.
A. Kitselman, L. E. Tompkins, G. C. T. Curtis and F. M. Kerton,
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Catal. Sci. Technol., 2014, 4, 1513‐1528.
20 (a) B. Xin and J. Hao, Chem. Soc. Rev., 2014, 43, 7171‐7187;
(b) K. Pohako‐Esko, M. Bahlmann, P. S. Schulz and P.
Wasserscheid, Ind. Eng. Chem. Res., 2016, 55, 7052‐7059;
(c) A. H. Jadhav, G. M. Thorat, K. Lee, A. C. Lim, H. Kang
and J. G. Seo, Catal. Today, 2016, 265, 56–67; (d) V.
Hiremath, A. H. Jadhav, H. Lee, S. Kwon and J. G. Seo, Chem.
Eng. J., 2016, 287, 602‐617; (e) B. Sarmah and R. Srivastava,
Ind. Eng. Chem. Res., 2017, 56, 8202‐8215.
21 (a) X. L. Shi, Y. Chen, P. Duan, W. Zhang and Q. Hu, ACS
Sustainable Chem. Eng., 2018, 6, 7119‐7127; (b) M.
Taheri, M. Ghiaci and A. Shchukarev, New J. Chem., 2018,
42, 587‐597; (c) W. Zhang, Q. Wang, H. Wu, P. Wu and M.
He, Green Chem., 2014, 16, 4767‐4774.
22 (a) P. V. D. Voort, D. Esquivel, E. D. Canck, F. Goethals, I. V.
Driessche and F. J. Romero‐Salguero, Chem. Soc. Rev., 2013,
42, 3913‐3955; (b) A. Walcarius and L. Mercier, J. Mater.
Chem., 2010, 20, 4478‐4511; (c) B. Guan, Y. Cui, Z. Ren, Z.
Qiao, L. Wang, Y. Liu and Q. Huo, Nanoscale, 2012,
6596; (d) M. A. Wahab and J. N. Beltramini, RSC Adv., 2015,
, 79129‐79151.
23 (a) M. Waki, Y. Maegawa, K. Hara, Y. Goto, S. Shirai, Y.
Yamada, N. Mizoshita, T. Tani, W. J. Chun, S.
4, 6588‐
5
Muratsugu, M. Tada, A. Fukuoka and S. Inagaki, J. Am.
Chem. Soc., 2014, 136, 4003‐4011; (b) L. Wu, Y. Yang, Y.
Ye, Z. Yu, Z. Song, S. Chen, L. Chen, Z. Zhang and S. Xiang,
ACS Appl. Energy Mater., 2018, 1, 5068‐5074; (c) L. M.
Reid and C. M. Crudden, Chem. Mater., 2016, 28, 7605‐
7612.
24 (a) M. Guan, W. Wang, E. J. Henderson, Ö. Dag, C.
Kübel, V. S. K. Chakravadhanula, J. Rinck, I. L.
Moudrakovski, J. Thomson, J. McDowell, A. K. Powell, H.
Zhang and G. A. Ozin, J. Am. Chem. Soc., 2012, 134, 8439‐
8446; (b) S. Parambadath, A. Mathew, M. J. Barnabas, K.
M. Rao and C. S. Ha, Micropor. Mesopor. Mat., 2016, 225
174‐184.
,
25 (a) S. J. Zhang and X. M. Lu, Ionic liquids: from
fundamental research to industrial applications, Science
Press, Beijing, 2006; (b) D. S. Karousos, A. I. Labropoulos,
A. Sapalidis, N. K. Kanellopoulos, B. Iliev, T. J. S. Schubert
and G. E. Romanos, Chem. Eng. J., 2017, 313, 777‐790;
(c) I. del Hierro, Y. Pérez and M. Fajardo, Mol. Catal.,
2018, 450, 112‐120.
26 (a) P. Ossowicz, E. Janus, A. Szady‐Chełmieniecka and Z.
Rozwadowski, J. Mol. Liq., 2016, 224, 211‐218; (b) K.
Hanke, M. Kaufmann, G. Schwaab, M. Havenith, C. T.
Wolke, O. Gorlova, M. A. Johnson, B. P. Kar, W. Sander
and E. Sanchez‐Garcia, Phys. Chem. Chem. Phys., 2015, 17
,
8518‐8529.
27(a) M. Liu, K. Gao, L. Liang, F. Wang, L. Shi, L. Sheng
and J. Sun, Phys. Chem. Chem. Phys., 2015, 17, 5959‐
5965; (b) D. H. Lan, H. T. Wang, L. Chen, C. T. Au and S. F.
Yin, Carbon, 2016, 100, 81‐89; (c) R. Srivastava, D.
Srinivas and P. Ratnasamy, Micropor. Mesopor. Mat.,
2006, 90, 314‐326; (d) S. Gallardo‐Fuentes, R. Contreras,
8 |New J. Chem., 2017, 00, 1‐3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 9 of 9
New Journal of Chemistry
1
2
3
4
5
View Article Online
DOI: 10.1039/C8NJ05273E
Graphical Abstract
6
7
8
9
Novel and effective strategy of dual bis(trifluoromethylsulfonyl)imide
imidazolium ionic liquid immobilized on periodic mesoporous
organosilica-mediated greener cycloaddition of carbon dioxide to
epoxides
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Jin Tan,a Dong Fang,b Yang Liua and Yu Lin Hu*a
O
R
CO2
O
O
O
O
R
O Si
O
O
N
N
N
N
NTf2
O
S
i
O
N
T
f2
PMO@IL-NTf2
cooperative green catalysis
Novel periodic mesoporous organosilica supported ionic liquids were prepared, characterized and
evaluated as catalysts for cycloaddition of CO2 to epoxides.