A heterogenized cobaltate catalyst on a bis-imidazolium-based covalent triazine framework for hydroesterification of epoxides

Article abstract of DOI:10.1039/C8NJ02292E

An imidazolium-cobaltate-based heterogeneous catalyst exhibits advantages over its homogeneous counterpart in the synthesis of β-hydroxyesters from epoxides. However, leaching of cobaltate from the catalytic support decreases the selectivity and recyclability of the catalyst. To overcome such drawbacks, a bis-imidazolium-based covalent triazine framework (CTF) is employed as a catalytic support for the hydroesterification catalyst to reduce cobaltate leaching by the intramolecular anion stabilization effect of the multi-imidazolium moiety, resulting in an excellent selectivity for the β-hydroxyester and unprecedented recyclability.

Full text of DOI:10.1039/C8NJ02292E

View Article Online
View Journal
NJC
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: S. Rajendiran, G.
H. Gunasekar and S. Yoon, New J. Chem., 2018, DOI: 10.1039/C8NJ02292E.
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 8
View Article Online
DOI: 10.1039/C8NJ02292E
Journal Name
ARTICLE
A heterogenized cobaltate catalyst on bis-imidazolium-based
covalent triazine framework for hydroesterification of epoxides
Senkuttuvan Rajendiran, Gunniya Hariyanandam Gunasekar and Sungho Yoon*
Received 00th January 20xx,
Accepted 00th January 20xx
A imidazolium-cobaltate-based heterogeneous catalyst exhibits advantages over its homogeneous counterpart in the
DOI: 10.1039/x0xx00000x
synthesis of β-hydroxyesters from epoxides. However, leaching of cobaltate from the catalytic support decreases the
www.rsc.org/
selectivity and recyclability of the catalyst. To overcome such drawbacks, bis-imidazolium-based covalent triazine
framework (CTF) is employed as a catalytic support for hydroesterification catalyst to reduce cobaltate leaching using the
intramolecular anion stabilization effect of multi-imidazolium moiety, resulting in excellent selectivity for the
β-
hydroxyester and unprecedented recyclability.
imidazolium ions in the catalytic process. Therefore to
enhance the stability of the
Co(CO)4]−
[
Introduction
β
-
hydroxyesters are versatile reagents that are used to
generate numerous chemical products, including 1,3-
alkanediols,1-4 -unsaturated esters,5-9 and biodegradable
α,β
polyesters,10-11 and widely regarded as drug candidates for
anti-Alzheimer and anti-Parkinson treatments and for the
treatment of other central nervous system disorders.12-19
Metal-catalyzed epoxide carbonylation using homogeneous
catalyst is a simple and inexpensive method to produce
hydroxyesters from epoxides.3,4,20 It can also be used to
produce
-lactones21-25 and -hydroxy acids.26 Several
homogeneous cobaltate catalysts such as
β-
β
β
ions, the effect of intramolecular di-cation anion interactions
was introduced within the framework through the
introduction of an auxiliary imidazolium moiety (Fig. 1). In
addition, this strategy would increase the number of Lewis
acidic imidazolium groups in the framework, thereby
increasing epoxide activation while simultaneously allowing
rapid CO insertion, leading to better selectivity for ester
production. Herein, we demonstrated the synthesis,
characterization, and catalytic activity of a bis-imidazolium-
based covalent triazine framework (CTF) heterogeneous
system, i.e., [bis-imidazolium-CTF][Co(CO)4], for the
dicobaltoctacarbonyl,27-32 pyridinium cobaltate,33 and
imidazolium cobaltate complexes3,4,20 have been reported.
Although most of these catalytic systems are active, their poor
recyclability and complicated catalyst separation procedures
restrict their use in industry. To overcome these drawbacks, a
polymeric supported pyridinium-cobaltate heterogeneous
catalysts were reported for hydroxyesters generation.34,35
However, their product selectivity and poor catalyst recycling
still limit their practical applications. Recently, we reported an
ionic-liquid-based heterogenized imidazolium cobaltate
catalyst for the production of
β-hydroxyesters from
conversion of epoxides to β-hydroxyesters are reported, and
the facile separation of the catalyst and recyclability are
epoxides,20 in which the selectivity of ester product was
reduced during the recycling process owing to the easy
dissociation of [Co(CO)4]− ions from the framework. The
dissociation possibly originates from the weakly stabilized
demonstrated.
Results and discussion
Recently, CTFs are gaining increased attention as catalytic
supports because they are highly porous, robust under high
pressure and thermal conditions, and stable in both acidic and
basic conditions.36-46 In the present study, CTF containing bis-
imidazolium moiety is used as a support to incorporate [Co(CO)4]-
ions into the framework by maintaining the high surface area and
large pore volume. To prepare the designed catalytic support
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 2 of 8
View Article Online
DOI: 10.1039/C8NJ02292E
ARTICLE
Journal Name
microporous and mesoporous characteristics with an average
pore diameter of 3.2 nm (Table S1).52,53 Based on the pore size
through a simple calculation, the porous framework of the
materials is represented in the Scheme 1.54 The Brunauer–
Emmett–Teller (BET) surface area was found to be 830 m2 g−1
with an average pore volume of 0.44 cm3 g−1. In addition, NL-
DFT pore distribution calculations clearly indicate the
existence of micropores (0.55 nm to 1.17 nm) and mesopores
(2 nm to 4 nm) (Fig. S6).
To investigate the bonding and electronic environment in
2, X-ray photoelectron spectroscopy (XPS) was carried out.
The C 1s XPS spectrum of 2 was deconvoluted into four peaks
with binding energies (BEs) of 284.6, 285.8, 286.3, and 288.1
eV, which correspond to the C=C/C-C/C-H, C=N, C-N, and N-C-
N groups, respectively, of the imidazolium and triazine species
(Fig. 4).55 In addition, the C 1s XPS spectrum of
2
shows the
Scheme 1. (i) ZnCl2, 400 οC, 48 h. (ii) KCo(CO)4, MeOH, 50 οC, 0.5 MPa of CO, 24 h
same BEs for imidazolium species as those in
1
(Fig. S7). The
deconvoluted N 1s spectrum shows peaks at 398.4 eV for the
triazine nitrogen and 400.5 eV for the imidazolium nitrogen
(Scheme 1), quaternized dicationic bis-(imidazolium)methane
bromide (1) was prepared with 50% yield by coupling
bis(imidazolyl)methane with 4-cyanobenzyl bromide (the synthetic
route and detailed characterization are given in the electronic
species (Fig. S8).56 These results collectively confirm that
2 has
both triazine and imidazolium moieties in its framework, and
its high porosity indicates that the Cl− anion existing in
2 can
undergo facile anion exchange.
Accordingly, the endogenous anion (Cl−) in
supporting Information (ESI)). Using 1 as
a monomer, [(bis-
2 undergoes
imidazolium)-CTF]Cl (2) was observed as a hard black solid via
trimerization at 400 °C using ZnCl2 as both the solvent and a Lewis
acid catalyst (the synthetic procedure is given in the ESI).
facile exchange with the exogenous guest [Co(CO)4] anion
from K[Co(CO)4] in methanol under CO atmosphere. SEM-EDS
analysis of formed black solid [bis-imidazolium-CTF][Co(CO)4]
(3) shows unchanged irregular blocks with a homogeneously
distributed cobalt content (Fig. 3b and S9). The accurate
cobalt content measured using inductively coupled plasma-
optical emission spectroscopy (ICP-OES) is 1.57 wt%, which is
significantly lower than the theoretically calculated fully
exchanged cobalt content (16.32 wt%) (Scheme 1). Moreover,
TEM images (Fig. 3c and Fig S5) indicate that the immobilized
Co content did not block the entire porosity of the materials,
and the scanning transmission electron microscopy (STEM)-
EDS map shown in Fig. 3d demonstrates the distribution of Co
metal in the pores of the sample. Further a decreased BET
Fourier-transform infrared spectroscopy (FT-IR) analysis
was conducted to investigate the structure of
2 (Fig.2). The
absence of a CN stretching peak at 2200 cm−1 indicates
successful trimerization, and the weak C=N and C=C signals
around 1550–1350 cm−1 indicate the presence of imidazolium
rings and triazine units. Furthermore, 13C cross-polarization
magic-angle spinning solid-state nuclear magnetic resonance
spectroscopy analysis indicates the formation of local
structures of
2. A broad peak at around 100–165 ppm
indicates the presence of imidazolium and triazine carbon
signals (CN, C=C, and C-N), which matches well with the
imidazole carbon signals of
of triazine, confirming the formation of
The polymeric solid was analyzed by powder X-ray
diffraction (Fig. S2), where the broad peaks at 25ο and 44 ο
indicate that the material is amorphous in nature.
Furthermore, thermogravimetric analysis (TGA) of shows
thermal stability up to 478 C (Fig. S3). The morphology and
porous nature of were analyzed by scanning electron
1
and the reported carbon signals
surface area and pore volume of
3
to 570 m2 g−1 and 0.28 cm3
2
(Fig.S1).
g−1, respectively was observed after Co(CO)4 immobilization
(Fig. 2 and Table S1). Interestingly, the NL-DFT spectrum (Fig.
S10) shows decreased peak intensities (0.55 nm to 4 nm),
indicating that some of the micropores and mesopores are
occupied with [Co(CO)4]− ions. However, the spectrum shows
that there are still some unblocked pores in the material for
2
2
2
ο
2
microscopy (SEM) and transmission electron microscopy
(TEM). The SEM image (Fig. 3a) shows irregular blocks with a
300
Adsorption
Desorption
Surface area = 830 m2/g
Total pore volume = 0.44 cm3/g
mean size of >35 ꢀm, and the energy-dispersive X-ray
spectroscopy (EDS) mapping results indicate the uniform
CN
150
Surface area = 570 m2/g
Total pore volume = 0.28 cm3/g
distribution of carbon, nitrogen, and chloride ions (Fig S4). In
the high-resolution TEM of
formation throughout the sample (Fig. S5).47-51 Further to
characterize the porous properties of , nitrogen sorption
measurements were performed at 77 K. As shown in Fig. 2,
2 reveals porous network
C=N, C=C
C-N, C-C
2
0
4000
3000
2000
1000
0.5
1.0
Wavenumber ( )
cm-1
2
Relative pressure (P/P
0)
Fig. 2. (Left) FT-IR spectra of (―) 1, (―) 2, and (―) 3. (Right) Nitrogen sorption
presents a type IV isotherm (IUPAC classification) with
hysteresis loop implying that the material has both
isotherms of 2 (above) and 3 (below).
2 | J. Name., 2012, 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 8
View Article Online
DOI: 10.1039/C8NJ02292E
Journal Name
ARTICLE
imidazolium cobaltate material20 but the exact reason for the
CO peak not appearing is still not known.
a
b
Finally, CHN elemental analysis shows an increased carbon
content for 3, which reiterates the existence of [Co(CO)4]− ions
in the framework (Table S2). Thus, these characterization
techniques have confirmed that a porous material is formed
as proposed in Scheme 1. Consequently, the hierarchical
material
active sites for improved carbonylation activity.
Once had been thoroughly characterized, we used it to
3 will exhibit efficient mass transfer of epoxide to its
50 ꢀm
50 ꢀm
c
d
3
catalyze epoxide carbonylation in a 100 mL stainless steel
tube reactor using methanol as both the reactant and solvent.
Propylene oxide (PO) was used to screen the reaction
conditions because it is readily available and less toxic (Table
1). Interestingly, the carbonylation of PO using the
heterogeneous catalyst [imidazolium-CTF][Co(CO)4] (4)
(substrate to catalyst ratio (S/C) = 40) results in a PO
conversion of >99% over 24 h at 90 οC under 6.0 MPa CO,
forming a mixture of methyl 3-hydroxybutyrate (MHB), 1-
100 nm
Fig. 3. SEM images of (a) 2 and (b) 3. TEM images of (c) 3 and (d) STEM-EDS mapping
of Co in 3.
methoxy propanol (1-MP), and acetone at
a ratio of
the mass transfer of small molecules. These results
collectively indicate the existence of cobalt in the framework.
8.6:1.0:0.4 (entry 1).20 Notably, side products 1-MP and 2-
methoxy propanol (2-MP) are directly formed by the reaction
of PO and MeOH at higher temperature, and thus are
unavoidable, while acetone is formed by a 1,2-hydride shift in
Catalyst
3 was subjected to XPS analysis to confirm the
presence of Co anions and the existence of a peak in C 1s
spectrum corresponds to CO in [Co(CO)4]− ions. Peaks with BEs
of 284.6, 285.8, 286.3, and 288.1 are observed corresponding
to the C=C/C-C/C-H, C=N, C-N, and N-C-N groups of the
imidazolium and triazine species, respectively (Fig. 4). The
new peak at 289.2 eV is assigned to the CO in the [Co(CO)4]-
species (Fig. 4). The XPS C 1s spectrum of K[Co(CO)4] exhibits a
peak at 289.2 eV corresponding to CO (Fig. S11). Thus, the
nitrogen sorption and XPS results confirm the existence of
PO.20 Then, we tested the catalytic activity of
3 using the same
substrate ratio as those used for entry 1, resulting in >99% PO
conversion when the reaction temperature is decreased to 75
οC for 11 h (entry 2). Further, the catalytic efficiency of
3 was
ο
examined by increasing the PO ratio to 60 at 75 C under 6.0
MPa CO for 11 h only 76 % conversion with 90 % of MHB
selectivity was observed and 24 % of PO remained unreacted
[Co(CO)4]− species in
same BEs as those for
imidazolium nitrogen species in the frameworks are
unchanged (Fig. S12). The peaks for at 781.4 eV and 796.9
3. The N 1s spectrum of
3 presents the
(entry 3).The maximum catalytic efficiency of
ο
3 is observed
when the PO ratio is increased to 60 at 75 C under 6.0 MPa
CO for 24 h (entry 4). Thus, the maximum turnover number
2
, which confirms that the triazine and
(TON) 60 is achieved with
compared to that for catalyst
3 at a lower temperature as
3
4
, which is the highest value
eV correspond to Co-2p3/2 and Co-2p1/2, respectively (Fig. 4),
which match well with previously reported XPS results for
[bpy-CTF-Al(OTf)2][Co(CO)4] and [imidazolium-CTF][Co(CO)4]
complexes.24,20 However, the FT-IR spectrum of
3 did not
show the CO stretching peaks of [Co(CO)4]− ions (Fig. 2).
Notably, similar IR results were observed for the CTF-based
160
781.4 eV
284.6 eV
284.6 eV
6000
6000
4000
4000
80
796.9 eV
285.8 eV
2000
286.3 eV
2000
285.8 eV
282
286.3 eV
288.1 eV
288.1 eV
289.2 eV
0
0
0
294
291
288
285
282
294
291
288
285
820
810
800
790
780
770
Binding energy (eV)
Binding energy (eV)
Binding energy (eV)
Fig 4. XPS spectrum of 2 C-1s (left), 3 C-1s (middle) and Co-2p (right). Solid blue and red lines are deconvoluted peaks of original dotted black lines. Green solid line is C-1s
peak for CO in Co(CO)4 ion.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 4 of 8
View Article Online
DOI: 10.1039/C8NJ02292E
ARTICLE
Journal Name
Table 1. Catalytic ability of ring-opening carbonylation of PO using catalyst 3 and 4a
Selectivity (%)b
Temp
(°C)
90
75
75
75
75
75
Time
(h)
24
11
11
24
24
24
Conversion
(%)b
>99
Entry
Catalyst
S/C
MHB
86
92
90
93
92
-
1-MP
10
4
Acetone
2-MP
1
2
3
4
4
3
3
40
40
60
60
60
60
40
4
4
5
4
4
4
4
-
-
-
-
-
>99
76c
>99
5
3
3
5
3d
3e
>99
>99
>99
4
86
11
6
10
-
720
[Bmim][Co(CO)4]
75
11
85
aReaction performed in 2.5 mL of MeOH, CO pressurized to 6.0 Mpa at room temperature. S/C-Substrate catalyst ratio. bDetermined by 1H-NMR spectroscopy with
naphthalene as an internal standard. cRemaining were unreacted PO. dsolid catalyst from hot filtration test, efiltrate from hot filtration test. [Bmim][Co(CO)4] - 1-butyl-
3-methylimidazolium cobalt tetracarbonyl, MHB - methyl-3-hydroxybutyrate, 1-MP - 1-methoxypropanol, 2-MP - 2-methoxypropanol.
reported to date.20 The catalytic results observed demonstrate slower reactivity compared to those of alkyl-substituted
that the formed bis-imidazolium-functionalized framework has epoxides (entry S5 and S6). Alkene- and ether-substituted
the ability to activate more epoxide as well as decrease epoxide substrates also afford their corresponding esters with
cobaltate ion leaching from the framework owing to excellent selectivity (entries S7–S9). Because of the limited
intramolecular stabilization by nearby imidazolium cations,57-62 mesoporous sites in the framework, the activity of the aryl-
which was not observed for the mono-imidazolium moiety
4.
substituted epoxides is restricted to 73% and 80%, respectively
To confirm this, ICP-OES analysis of the filtrate was performed, (entries S10–S11).
revealing the complete absence of cobalt. In addition, to
confirm the stability of the catalyst and to assess cobalt
Based on our understanding and the reported evidence,20-
24,26
here we propose a possible mechanism for epoxide
and also side-product
in methanol at 75 °C, cooling to room temperature, generation (Fig. 5). Notably, some reports demonstrate the
leaching, a hot filtration test was performed by heating hydroesterification using catalyst
catalyst
3
3
and filtering. Then, the filtrate and catalyst were used epoxide activation through the acidic hydrogen site (C-H). On
separately for PO carbonylation at 75 °C under 6.0 MPa CO for the other hand, few reports suggest through the imidazolium
24 h. The filtrate did not generate any ester product, but only ring by itself.3,4,63,64 Since we currently do not clearly
small amounts of acetone, 1-MP, and 2-MP side products, understand which site activates epoxide in the proposed
whereas the solid catalyst generated 92% ester product. This mechanism, we simply denote activation of epoxide through
result further indicates the reproducible activity of catalyst
(Table 1, entries 5 and 6). These results confirm that catalyst
3
3
imidazolium compound as shown in a, followed by nucleophilic
attack of [Co(CO)4]− on the less hindered carbon atom resulting
is highly active for the conversion of PO to ester and cobaltate in ring-opening of the epoxide to form a metal-alkyl bond (
anion stability is maintained. Although this catalyst shows
b).
increased stability and activity on epoxide carbonylation, the
turnover frequency (TOF) was limited to 2.5 h-1 which is lesser
than the homogeneous catalyst (entry 7, TOF 3.6 h-1)20.
In addition, to evaluate the catalyst porosity and stability
among various functional epoxides, the substrate scope of
3
was examined with different epoxides, and the results are
shown in Table S3 (ESI). The substrate/catalyst ratios were
optimized to attain better selectivity over 24 h at 75 °C. As
shown in Table S3, entry S1, mono-substituted alkyl epoxides
undergo facile carbonylation with excellent selectivity up to
89%. Interestingly, the substrate with more than one epoxide
group, i.e., 1,2,7,8-diepoxyoctane, also undergoes both
quadruple and sole carbonylation to produce products with
selectivities of 69% and 24%, respectively (entry S2). The di-
substituted 2,3-epoxybutane and cyclohexene oxide react
more slowly due to their bulky substitution. Owing to the
limited pore size of 3, real-time approach towards the active
site of the catalyst was partially hindered (entries S3 and
S4).Unprotected alcoholic epoxide and epichlorohydrin are
challenging substrates for hydroesterification owing to its
Fig. 5 Proposed mechanism of epoxide ring-opening carbonylation and side-
product formation.
4 | J. Name., 2012, 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 8
View Article Online
DOI: 10.1039/C8NJ02292E
Journal Name
ARTICLE
The CO in the pores of
3
undergoes a rapid migratory insertion to the weak ionic interaction between the imidazolium cation
. It further reacts with and cobalt anion.
methanol via intermolecular addition to form the To investigate the possibility of increasing or incorporating
into the cobalt-alkyl bond to form
c
β
-
hydroxyester. Meanwhile, released [Co(CO)4] ions are the cobalt content in the recycled catalyst, a sample of
stabilized by the nearby imidazolium ions, which prohibits the recovered catalyst was treated with freshly prepared
cobaltate leaching from the frameworks and regenerates K[Co(CO)4] in methanol (procedure given in the ESI). PO
catalyst
However, if intermediate (b) is sufficiently long-lived, the (cobalt content 1.62 wt%) under the same conditions, resulting
cobalt-alkyl adduct can undergo -elimination, followed by in the generation of the hydroxyester (94%) with an overall
enolate protonation and tautomerization to form acetone ( ). conversion efficiency of >99% (entry 6). These results show
At higher temperature, the available epoxide reacts directly that the heterogeneous catalyst retains its activity for
with methanol to form side products ( ). effective carbonylation after regeneration, making an
3
for the next cycle.
carbonylation was performed with the regenerated catalyst
β
d
3
e
3
For a heterogeneous catalyst to be viable for industrial attractive catalyst for industrial applications.
applications, it must satisfy recyclability and stability criteria. Conclusions
The excellent conversions and selectivities achieved (Table 1)
encouraged us to investigate the recyclability of the catalyst [bis-imidazolium-CTF][Co(CO)4]
under similar reaction conditions. After the initial run, the thoroughly characterized. The catalytic system efficiently
heterogeneous catalyst was separated from the reaction converts epoxides into
-hydroxyesters at 75 οC under 6.0 MPa
In summary, bis-imidazolium-based heterogeneous catalyst
was synthesized and
3
β
mixture by simple filtration and washed with methanol for CO with a TON of 60. The excellent activity may originate from
further use. EDS mapping (Fig. S13) shows the uniform the presence of the bis-imidazolium moieties, which activate
distribution of cobalt and the ICP-OES result reveals more epoxides simultaneously and prevent cobaltate from
unchanged cobalt content in the sample. These results leaching through intramolecular anion stabilization. Moreover,
indirectly show that the intramolecular anion stabilization the improved recyclability and regeneration of this catalyst
effect holding the cobaltate around the imidazolium ion from provides a new catalytic platform for epoxide conversion in
leaching. In addition, the XPS results for the recycled catalyst industry.
are the same as those for catalyst
The recovered catalyst was used for a second run at 75 οC General Considerations and Physical Measurements
under 6.0 MPa CO and the results are shown in Table 2. All manipulations of air and water-sensitive compounds
3 (Fig. S14, S15, and S16). Experiment Section
Through the five runs, overall activity is maintained at ~95%, were carried out in glove box. All the chemicals purchased
and it is noteworthy that upon recycling, the relative amounts were of analytical grade from Tokyo chemical Industry and
of acetone and 1-MP generated are largely maintained Sigma-Aldrich were used as received unless mentioned
(reproducibility of the recycling experiments were given in ESI otherwise.
Tetrahydrofuran
was
refluxed
over
(Table S4)). This partially reduced activity is ascribed to the sodium/benzoquinone and distilled under N2 atmosphere.
slow separation of [Co(CO)4] ions from the framework, which MeOH was refluxed over Mg/I and distilled under N2
was confirmed from the ICP-OES analysis of the cobalt content atmosphere. PO and acetonitrile was distilled over calcium
separated from
Table 2. Recycling ability of 3a.
hydride under N2 atmosphere. KCo(CO)4 was prepared by
following reported procedure.20 All new compounds were fully
characterized by standard spectroscopic techniques.
Deuterated solvents were purchased from Cambridge Isotope
laboratories, Inc., and used as received. NMR spectra were
recorded on a Bruker Advance IV (400 MHz) at 298 K and
chemical shifts were referenced to TMS Peak. IR spectra were
collected on a Nicolet iS 50 (Thermo Fisher Scientific)
spectrometer using KBr techniques. Scanning electron
microscopy (SEM) and energy-dispersive spectroscopy (EDS)
were measured on a JEOL LTD (JAPAN) JEM-7610F operated
Time
(h)
Conversion
(%)b
Selectivity (%)b
Cycle
MHB
93
1-MP Acetone
1
2
24
24
24
24
24
24
>99
97
3
3
4
5
5
3
4
5
5
5
6
3
92
3
95
91
4
92
90
5
6c
90
89
>99
94
at
adsorption/desorption was measured at 77
automated gas sorption system (Belsorp II mini, BEL japan,
Inc.,). Cobalt content in complex was determined using
an
accelerating
voltage
of
15.0
kV.
N2
aReaction performed in 2.5 mL of MeOH using pressurized CO at room
temperature. S/C ratio = 60/1. bDetermined by 1H-NMR spectroscopy. 1-MP = 1-
methoxy propane. cafter the fifth run catalyst 3 was regenerated with fresh
K[Co(CO)4]
K
using an
3
Inductively Coupled Plasma Optical Emission Spectroscopy
(ICP-OES) (iCAP-Q, Thermo Fisher scientific) using microwave
assisted acid system (MARS6, CEM/U.S.A). X-ray photoelectron
Spectroscopy (XPS) analysis was performed on ESCA 2000 (VG
microtech) at a pressure of ~3 x 10-9 mbar using Al Ka as the
excitation source (hγ=1486.6 eV) with concentric
hemispherical analyzer. Powder X-ray diffraction (PXRD) was
the fifth run of the reaction mixture is 1.48 wt%, and the XPS
BEs for cobalt remain unaffected (Fig. S17). Even though, we
considered that the bis-imidazolium moiety controls the
cobaltate ion from leaching, but still there is a separation of
cobaltate observed during the reaction process, which is due
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 6 of 8
View Article Online
DOI: 10.1039/C8NJ02292E
ARTICLE
Journal Name
measured on an RIGAKU D/Max 2500V using Cu (40 kV, 30 mA) Br ions signals in the sample. 13C CPMAS ssNMR δ [ppm] 165-
radiation. The elemental analysis was performed with an 100 (CN, C=C, and C-N), FT-IR = 1550-1350 (C=N, C=C, C-N)
elemental analyzer (Vario Micro cube, Germany). 13C cross- cm−1
polarization magic-angle spinning solid-state nuclear magnetic Synthesis of [bis-imidazolium-CTF][Co(CO)4]xCl(2-x) (3)
resonance spectroscopy (13C CPMAS ssNMR) data were
In a glove box, a tube reactor was charged with [bis-
acquired at ambient temperature on 400 MHz Solid state NMR imidazolium-CTF]Cl2 (0.454 g) and KCo(CO)4 (1.25 g, 5.952
spectrometer (AVANCE III HD, Bruker, Germany) at KBSI mmol) in 10 mL of MeOH. The reactor was purged with CO at
Western Seoul center with an external magnetic field of 9.4 T. room temperature, then pressurized with 0.5 MPa CO, and
The operating frequency was 100.66 MHz for 13C and the heated to 50 C for 24 h. After the reaction time, the reactor
ο
spectra were referenced to TMS. The samples were contained was cooled to room temperature and CO gas slowly vented
in HX CPMAS probe, with
Thermogravimetric analysis (TGA) was performed on Q600 acetone and transferred in to the glove box. The black
analyzer (TA Instrument, US) with a heating rate of 10 C per precipitate was filtered and washed with MeOH (4X15 mL) and
minute up to 800 C under nitrogen atmosphere. Research- dried under vacuum overnight. Yield=0.461 g.
grade carbon monoxide was purchased from Sinyang Gas General procedure for epoxide-ring opening carbonylation
Company, Korea, with 99.995% purity used as received. All In a glovebox, a 100 mL stainless steel tube reactor was
carbonylation reactions were performed in a 100-mL stainless equipped with magnetic stir bar and charged with
steel reactor and fitted with a pressure gauge and pressure corresponding amount of catalyst and PO in 2.5 mL of dry
4 mm o.d. Zirconia rotor. inside fume hood. The reactor was purged with N2, wiped with
°
°
a
3
release valve. All carbonylation reactions were set up and run methanol. The tube reactor was cooled to 0 oC, purged with
in a well-ventilated fume hood equipped with a carbon 0.5 MPa of CO. Then pressurized with desired CO pressure and
monoxide detector (see MSDS for proper handling of CO). PO heated to the desired temperature. After the reaction time,
conversion, ester products, 1-Methoxypropanol (1-MP), 2- the reactor was cooled to room temperature and CO gas was
1
Methoxypropanol (2-MP), and acetone were quantified by H slowly released inside fume hood. The crude sample was
filtered through celite, weighed and analyzed using 1H-NMR
NMR using naphthalene as an internal standard.
Synthesis of 1,1'-methylene bis(3-(4-cyanobenzyl)-1H- spectroscopy in CDCl3 with naphthalene as an internal
imidazol-3-ium) bromide (1)
standard.
To a solution of bis-(imidazole) methylene (2.031 g, 13.707
mmol) in dry acetonitrile (5 mL), was added 4-cyanobenzyl
bromide (5.374 g, 27.413 mmol). The colorless solution was
Conflicts of interest
heated to reflux for 16
h and then cooled to room
temperature. The resulting white precipitate was filtered and
recrystallized in methanol. Yield= 4.86 g 50%. 1H NMR (400
MHz, DMSO-d6) δ 9.64 (s, 1H), 8.16 – 8.05 (m, 1H), 8.02 – 7.87
(m, 3H), 7.64 (d, J = 8.4 Hz, 2H), 6.69 (s, 1H), 5.64 (s, 2H). 13C
NMR (400 MHz, DMSO-d6) δ [ppm] = 140.06, 138.72, 133.37,
129.82, 123.78, 123.26, 118.88, 112.09, 58.94, 52.10. MS (LC-
MS): m/z = 541.38 [M+H]+ (calcd. 540.21). FT-IR = 2200 (CN),
1650 (C=N), 1310 (C-N) cm−1
There are no conflicts to declare
Acknowledgements
We acknowledged financial support by the C1 Gas Refinery
Program through the National Research Foundation of Korea
(NRF) funded by the Ministry of Science, ICT & Future Planning
(2015M3D3A1A01064879).
Synthesis of [bis-imidazolium-CTF]Cl2 (2)
In a glove box,
1 (0.10 g, 0.185 mmol) and zinc chloride
(0.126 g, 0.925 mmol) were mixed in a 5 mL glass ampoule,
which was sealed under vacuum and heated to 400 οC in a
Notes and References
-1
ο
furnace at a heating rate of 60 C h . After 48 h, the furnace
was cooled to RT at a cooling rate 10 οC h-1. The black solid
blocks were ground well and stirred with 500 mL of water for 5
h, filtered and washed with water (200 mL) and acetone (200
mL). As documented, the strong impact on the formation of
the polymeric framework was influenced by maintaining the
Toxic chemical dicobaltoctacarbonyl and high pressured carbon
monoxide gas was used in the work.
1
B. N. Lee, E. J. Jang, J. H. Lee, R. H. Kim, Y. H. Han, H. K. Shin
and H. S. Lee, US patent 2003, 6617477 B2.
2
3
B. N. Lee and B. S. Chen EP 2004, 1122235 B1.
Z. M. Guo, H. S. Wang, Z. G. Lv, Z. H. Wang, T. Nie and W. W.
Zhang, J Organomet Chem, 2011, 696, 3668-3672.
Z. G. Lv, H. S. Wang, J. A. Li and Z. M. Guo, Res Chem
Intermediat, 2010, 36, 1027-1035.
J. M. Concellon, H. Rodriguez-Solla and V. del Amo, Synlett,
2006, DOI: 10.1055/s-2005-923592, 315-317.
L. Fernandes, A. J. Bortoluzzi and M. M. Sa, Tetrahedron,
2004, 60, 9983-9989.
ratio of the reactant
1 and ZnCl2 to 1:5. The formed black solid
as further refluxed with 1M HCl solution (150 mL) overnight to
remove excess and bounded ZnCl2 from the frameworks. The
resulting black solids were washed with H2O (3x150 mL),
methanol (3x150 mL) and acetone (3x150 mL). The black solid
4
5
6
7
ο
was dried under vacuum at 200 C for 16 h, Yield 0.8 g, 28%.
The energy dispersive spectroscopy (EDS) mapping
demonstrates most of the Br ions were exchanged with Cl ions
fig. S4 and in addition XPS spectrum Figure S8-1 did not show
J. M. Concellon, M. Huerta and R. Llavona, Tetrahedron Lett,
2004, 45, 4665-4667.
6 | J. Name., 2012, 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 8
View Article Online
DOI: 10.1039/C8NJ02292E
Journal Name
ARTICLE
8
9
K. Wadhwa and J. G. Verkade, J Org Chem, 2009, 74, 4368- 42 S. Dey, A. Bhunia, D. Esquivel and C. Janiak, J Mater Chem A,
2016, 4, 6259-6263.
4371.
J. l. Dever US patent 1965, 3182077.
43 R. Palkovits, C. von Malotki, M. Baumgarten, K. Mullen, C.
Baltes, M. Antonietti, P. Kuhn, J. Weber, A. Thomas and F.
Schuth, Chemsuschem, 2010, 3, 277-282.
10 K. Sudesh, H. Abe and Y. Doi, Prog Polym Sci, 2000, 25, 1503-
1555.
11 T. U. Gerngross and S. C. Slater, Sci Am, 2000, 283, 36-41.
12 J. Y. Zhang, Q. Cao, S. W. Li, X. Y. Lu, Y. X. Zhao, J. S. Guan, J.
44 S. Hug, M. E. Tauchert, S. Li, U. E. Pachmayr and B. V. Lotsch,
J Mater Chem, 2012, 22, 13956-13964.
C. Chen, Q. Wu and G. Q. Chen, Biomaterials, 2013, 34, 7552- 45 Y. Zhou, Z. H. Xiang, D. P. Cao and C. J. Liu, Chem Commun,
7562. 2013, 49, 5633-5635.
13 M. Zilberter, A. Ivanov, S. Ziyatdinova, M. Mukhtarov, A. 46 J. S. Lee, H. M. Luo, G. A. Baker and S. Dai, Chem Mater,
Malkov, A. Alpar, G. Tortoriello, C. H. Botting, L. Fulop, A. A. 2009, 21, 4756-4758.
Osypov, A. Pitkanen, H. Tanila, T. Harkany and Y. Zilberter, J 47 L. M. Tao, F. Niu, J. G. Liu, T. M. Wang and Q. H. Wang, Rsc
Neurochem, 2013, 125, 157-171. Adv, 2016, , 94365-94372.
14 L. Hertz, Y. Chen and H. S. Waagepetersen, J Neurochem, 48 S. Gopi and M. Kathiresan, Polymer, 2017, 109, 315-320.
6
2015, 134, 7-20.
15 K. Tieu, C. Perier, C. Caspersen, P. Teismann, D. C. Wu, S. D.
49 H. P. Ma, H. Ren, S. Meng, F. X. Sun and G. S. Zhu, Sci Rep-Uk,
2013, , 3611.
3
Yan, A. Naini, M. Vila, V. Jackson-Lewis, R. Ramasamy and S. 50 S. Yamaguchi, K. Kamiya, K. Hashimoto and S. Nakanishi,
Przedborski, J Clin Invest, 2003, 112, 892-901. Chem Commun, 2017, 53, 10437-10440.
16 M. A. Reger, S. T. Henderson, C. Hale, B. Cholerton, L. D. 51 X. M. Liu, H. Li, Y. W. Zhang, B. Xu, A. Sigen, H. Xia and Y. Mu,
Baker, G. S. Watson, K. Hyde, D. Chapman and S. Craft,
Neurobiol Aging, 2004, 25, 311-314.
17 V. Stojanovic and S. Ihle, Can Vet J, 2011, 52, 426-430.
Polym Chem-Uk, 2013, 4, 2445-2448.
52 R. Thangavel, A. G. Kannan, R. Ponraj, V. Thangavel, D. W.
Kim and Y. S. Lee, J Power Sources, 2018, 383, 102-109.
18 A. Paoli, A. Bianco, E. Damiani and G. Bosco, Biomed Res Int, 53 R. Thangavel, K. Kaliyappan, H. V. Ramasamy, X. L. Sun and Y.
2014, DOI: Artn 474296 S. Lee, Chemsuschem, 2017, 10, 2805-2815.
19 W. Y. Ma, J. Berg and G. Yellen, J Neurosci, 2007, 27, 3618- 54 J. Guo, Y. H. Xu, S. B. Jin, L. Chen, T. Kaji, Y. Honsho, M. A.
3625.
20 S. Rajendiran, K. Park, K. Lee and S. Yoon, Inorg Chem, 2017,
56, 7270-7277.
Addicoat, J. Kim, A. Saeki, H. Ihee, S. Seki, S. Irle, M.
Hiramoto, J. Gao and D. L. Jiang, Nat Commun, 2013,
55 B. Kumar, M. Asadi, D. Pisasale, S. Sinha-Ray, B. A. Rosen, R.
4.
21 Y. D. Y. L. Getzler, V. Mahadevan, E. B. Lobkovsky and G. W.
Coates, J Am Chem Soc, 2002, 124, 1174-1175.
Haasch, J. Abiade, A. L. Yarin and A. Salehi-Khojin, Nat
Commun, 2013, 4.
22 V. Mahadevan, Y. D. Y. L. Getzler and G. W. Coates, Angew 56 X. N. Li, S. Y. Bai, Z. J. Zhu, J. H. Sun, X. Q. Jin, X. Wu and J. Liu,
Chem Int Edit, 2002, 41, 2781. Langmuir, 2017, 33, 1248-1255.
23 J. A. R. Schmidt, V. Mahadevan, Y. D. Y. L. Getzler and G. W. 57 H. X. Zhao, L. Y. Li, Y. X. Wang and R. H. Wang, Sci Rep-Uk,
Coates, Org Lett, 2004, , 373-376. 2014, , 5478.
6
4
24 S. Rajendiran, P. Natarajan and S. Yoon, Rsc Adv, 2017,
4635-4638.
7,
58 V. Jancik and H. W. Roesky, Inorg Chem, 2005, 44, 5556-
5558.
25 H. D. Park, M. Dinca and Y. Roman-Leshkov, Acs Central Sci, 59 C. J. Serpell, R. Chall, A. L. Thompson and P. D. Beer, Dalton
T, 2011, 40, 12052-12055.
2017,
26 S. Rajendiran, G. Park and S. Yoon, Catalysts, 2017,
27 J. H. Liu, H. Wu, L. W. Wu, J. Chen and C. G. Xia, J Mol Catal
a-Chem, 2007, 269, 97-103.
28 J. Eisenmann, R. L. Yamartino and J. F. Howard, J Org Chem,
1961, 26, 2102-2104.
29 J. H. Liu, J. Chen and C. G. Xia, J Mol Catal a-Chem, 2006, 250
232-236.
3
, 444-448.
7
, 228.
60 H. Kim, S. In and J. M. Kang, Supramol Chem, 2006, 18, 141-
145.
61 R. Senkuttuvan, V. Ramakrishna, K. Bakthavachalam and N.
D. Reddy, J Organomet Chem, 2013, 723, 72-78.
62 J. C. Y. Lin, R. T. W. Huang, C. S. Lee, A. Bhattacharyya, W. S.
Hwang and I. J. B. Lin, Chem Rev, 2009, 109, 3561-3598.
63 F. D. Bobbink, D. Vasilyev, M. Hulla, S. Chamam, F. Menoud,
,
30 K. Igi, Y. Furukawa and Y. Takenaka, US Patent 2007, G. Laurenczy, S. Katsyuba and P. J. Dyson, Acs Catal, 2018, 8,
7256305 B2. 2589-2594.
31 S. E. Denmark and M. Ahmad, J Org Chem, 2007, 72, 9630- 64 A. L. Girard, N. Simon, M. Zanatta, S. Marmitt, P. Goncalves
9634.
and J. Dupont, Green Chem, 2014, 16, 2815-2825.
32 R. F. Heck, J Am Chem Soc, 1963, 85, 1460-1463.
33 F. G. Deng, B. Hu, W. Sun, J. Chen and C. G. Xia, Dalton T,
2007, 38, 4262-4267.
34 Y. Fan, Y. Liu, Y. Wang, H. Lu, B. Xu and J. Zhou, Canadian
Patent 2015, CN104841485 A.
35 Y. B. Liu, Y. N. Wang, H. M. Lu, S. Liang, B. L. Xu and Y. N. Fan,
Chem-Asian J, 2016, 11, 3159-3164.
36 Z. F. Wang, C. B. Liu, Y. Huang, Y. C. Hu and B. Zhang, Chem
Commun, 2016, 52, 2960-2963.
37 G. H. Gunasekar, K. Park, V. Ganesan, K. Lee, N. K. Kim, K. D.
Jung and S. Yoon, Chem Mater, 2017, 29, 6740-6748.
38 D. Beaudoin, T. Maris and J. D. Wuest, Nat Chem, 2013, 5,
830-834.
39 K. K. Wang, H. L. Huang, D. H. Liu, C. Wang, J. P. Li and C. L.
Zhong, Environ Sci Technol, 2016, 50, 4869-4876.
40 S. Hug, L. Stegbauer, H. Oh, M. Hirscher and B. V. Lotsch,
Chem Mater, 2015, 27, 8001-8010.
41 J. Roeser, K. Kailasam and A. Thomas, Chemsuschem, 2012,
5, 1793-1799.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins

New Journal of Chemistry
Page 8 of 8
View Article Online
DOI: 10.1039/C8NJ02292E
A recyclable heterogeneous [bis-imidazolium-CTF][Co(CO)4] complex that reduces
decomposition of cobaltate by intramolecular anion stabilization effects and efficiently converts
epoxide into
β-hydroxyester with excellent conversion (selectivity 93 %). Facile separation and
recyclability of the catalyst make it viable for industrial applications.