Directing two azo-bridged covalent metalloporphyrinic polymers as highly efficient catalysts for selective oxidation

Article abstract of DOI:10.1016/j.apcata.2014.10.023

Manganese meso-tetra (4-nitrophenyl)porphyrin (Mn-TNPP) with four nitro groups at periphery was employed as building moieties to condense with p-phenylenediamine and benzidine into extended π materials, respectively. Two covalent metalloporphyinic polymer

Full text of DOI:10.1016/j.apcata.2014.10.023

Applied Catalysis A: General 489 (2015) 117–122
Contents lists available at ScienceDirect
Applied Catalysis A: General
journal homepage: www.elsevier.com/locate/apcata
Directing two azo-bridged covalent metalloporphyrinic polymers as
highly efficient catalysts for selective oxidation
a,∗
a,∗
a
b
a
Weijie Zhang , Pingping Jiang , Ying Wang , Jian Zhang , Pingbo Zhang
a
The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University,
Wuxi 214122, China
School of Chemistry and Environmental Science, Lanzhou City University, Lanzhou 730000, China
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 28 June 2014
Received in revised form 11 October 2014
Accepted 13 October 2014
Available online 23 October 2014
Manganese meso-tetra (4-nitrophenyl)porphyrin (Mn-TNPP) with four nitro groups at periphery was
employed as building moieties to condense with p-phenylenediamine and benzidine into extended ␲
materials, respectively. Two covalent metalloporphyinic polymers (CMPs) linked by azo (
N N ) were
denoted as azo-CMP-1 and azo-CMP-2. FT-IR, XRD, SEM, TG, contact angle (CA) and XPS were used to
analyze and characterize the synthesized heterogeneous materials. The catalytic study has demonstrated
that azo-CMP catalysts displayed an excellent performance for epoxidation of olefins, especially cyclo-
hexene. When azo-CMP-1 was recycled five times, its catalytic activity remained with an inconspicuous
decrease. Additionally, azo-CMP series exhibited a amphipathic property evidenced by CA test, facilitat-
ing the diffusion of reactant into channels of azo-CMPs. Furthermore, the peak value of Mn2p3/2 shifting
to a higher value for azo-CMP-1 suggested that there was a catalysis-promoted electronic environment
around the Mn(III) active sites, compared to either azo-CMP-2 or homogenous sites.
Keywords:
Covalent-organic polymer
Biomimetic catalysis
Selective oxidation
Porphyrin
©
2014 Elsevier B.V. All rights reserved.
1
. Introduction
these porphyrins [6]. Currently, an additional strategy that has
spurred tremendous interest is to incorporate or encapsulate heme
into various networks, including metal metalloporphyrins-organic
frameworks (MMOFs) [7–13], covalent metalloporphyrinic frame-
works (CMFs) [14–17] and covalent metalloporphyrinic polymers
(CMPs) [18–22]. Among them, covalent metalloporphyrinic poly-
mers (CMPs) are the easiest to design and develop among the three
aforementioned classes of materials, they are non-crystalline and
have non-uniform pores that are typically somewhat ill-defined.
Therefore, there is an urgent need to develop novel CMPs to target
highly efficient bio-catalysts.
In fact, covalent organic polymers have been intentionally
fabricated since at least the early 1960s by incorporating func-
tional monomers into polymerization processes, yielding three-
dimensional (3D)-network materials [20,23]. Recent researches
focus on assembling novel linkages with light element composi-
tion, rigid nature and discrete bonding direction of arenes in order
to make aromatic ␲ systems [24–27]. This has potential to provide
a desirable platform for the design and development of CMP mate-
rials as promising heterogeneous bio-catalysts.
Activation of unsaturated bonds is a subject of escalating inter-
est in relation to the bio-inspired function mimicry of cyctochrome
P450, as well as the development of highly active catalysts for
selective oxidation reactions. Duplicating this impressive reactiv-
ity in synthetic systems has been the focus of intense research. In
particular, metalloporphyrins is a well-established building blocks
with catalytic active site to that of cyctochrome P450 and has been
developed for various oxidation reactions [1–3].
However, the further development of metalloporphyrins as
bio-catalyst in solution is still challenging, because of the recy-
clability drawback, formation of catalytically inactive dimers and
inevitably fast degradation in homogeneous catalysis [4]. Nev-
ertheless, several successful protocols have been formulated to
circumvent these challenges. One such example involves immo-
bilizing the porphyrins on insoluble supports, but this unavoidably
dilutes the density of the active sites [5]. Another strategy decorates
the porphyrin macrocycle with bulky functional groups to protect
the active sites, which is limited by the difficulty of synthesizing
From the point view of catalysis, the CMP with accessibility of
the open channels, can be considered as self-supported catalysts
with an enhanced performance due to their high-density active
sites into network. The tetrapyrrolic macrocycles of porphyrins
play an important role in the design of extended supramolecular
∗ Corresponding authors. Tel.: +86 510 85913617; fax: +86 13506196132.
E-mail addresses: fengyunzwj@126.com (W. Zhang), ppjiang@jiangnan.edu.cn
P. Jiang).
(
http://dx.doi.org/10.1016/j.apcata.2014.10.023
926-860X/© 2014 Elsevier B.V. All rights reserved.
0

1
18
W. Zhang et al. / Applied Catalysis A: General 489 (2015) 117–122
Fig. 1. Syntheses of two azo-CMPs. Green powders of azo-CMPs were obtained by reacting manganese meso-tetra (4-nitrophenyl)porphyrin, with two aromatic amines,
◦
namely p-phenylenediamine (azo-CMP-1) and benzidine (azo-CMP-2) in DMF at 150 C in the presence of potassium hydroxide under an atmosphere of N2.
lattices, which derives from their robust structure, remarkable
thermal and oxidative stability, and unique catalytic properties.
More importantly, the heterogeneous nature of CMPs can be very
useful to separate the catalyst from the products of interest, recover
it after simple filtration procedures and finally regenerate it for
successive catalytic runs. Therefore, this motivates us to target effi-
cient heterogeneous catalysts with open coordination frameworks
through novel linkage, which is essential to catalysis application.
With this background in mind, we reported the development
of new CMPs based on the azo ( N N ) linkage that exhibited
high performance on selective oxidation (Fig. 1). Accordingly, we
employed manganese meso-tetra (4-nitrophenyl)porphyrin (Fig. 1,
Mn-TNPP) with four nitro groups at periphery as amino compo-
nent to condense with nitro, in order to demonstrate the feasibility
of the strategy and features of various CMP catalysts. Catalytic
study has demonstrated that azo-CMP-1 and azo-CMP-2 can cat-
alyze the epoxidation of a variety of natural substrates, acting as an
effective peroxidase mimic. The reported azo linkage not only sta-
bilizes the catalytic sites by hindering it from forming catalytically
inactive dimers, but also endows the catalysts a rare amphipathic
property which facilitates the diffusion of reactants, together with
a catalysis-promoted electronic environment evidenced by XPS
study.
bottom flask equipped with a condenser, thermocouple and mag-
netic stirrer. KOH (0.16 g, 2.86 mmol) was added to this solution
while stirring. The temperature of the reaction mixture was
increased slowly up to 150 C with vigorous stirring under N2
atmosphere and stirred at this temperature for 24 h. The reaction
mixture was cooled to room temperature, added to 80 mL of dis-
◦
tilled H O and stirred for 1 h. Green precipitate was filtered off,
2
immersed in DMF for 1 day and then washed with warm distilled
H O (×5), Me CO (×5) and THF (×5). Subsequently, green precipi-
2
2
◦
tates were dried at 150 C under vacuum for 8 h to yield azo-CMP-1
(0.18 g) in 57% yield.
2.3. Synthesis of azo-CMP-2
Mn-TNPP (0.339 g, 0.4 mmol) and benzidine (0.147 g, 0.8 mmol)
were dissolved in DMF (25 mL) in a three-necked round bottom
flask equipped with a condenser, thermocouple and magnetic stir-
rer. KOH (0.22 g, 3.92 mmol) was added to this solution while
stirring. The catalyst amount in DMF solution was about 0.15 mmol
of KOH/mL DMF for both synthesis. The temperature of the reaction
◦
mixture was increased slowly up to 150 C with vigorous stirring
under N atmosphere and stirred at this temperature for 24 h. The
2
reaction mixture was cooled to room temperature, added to 100 mL
of distilled H O and stirred for 1 h. Green precipitate was filtered
2
off, immersed in DMF for 1 day and washed with warm distilled
2
. Experimental
H O (×5), Me CO (×5) and THF (×5). Subsequently, green precipi-
2
2
◦
tates were dried at 150 C under vacuum for 8 h to yield azo-CMP-2
2
.1. Manganese meso-tetra (4-nitrophenyl)porphyrin (Mn-TNPP)
The compound TNPP was prepared by the method described
(0.16 g) in 33% yield.
2.4. Measurement of catalytic performance
in the literature as follows [28]. 4-Nitrobenzaldehyde (22.0 g,
−
1
−1
1
.45 × 10 mol) and acetic anhydride (24.0 mL, 2.54 × 10 mol)
All of the reactions were carried out at desired temperature
was dissolved in propionic acid (600 mL). The solution was then
under air in a 50 mL flask equipped with a magnetic stirrer bar.
Olefin (500 mM), TBHP (1000 mM), catalyst (0.01 mmol, 5 mM),
acetonitrile (3.0 mL) sealed and bromobenzene as internal standard
−1
refluxed, to which pyrrole (10.0 mL, 1.44 × 10 mol) was slowly
added. After refluxing for 30 min, the resulting mixture was cooled
to give a precipitate which was collected by filtration, washed with
H O and methanol, and dried under vacuum. The resulting pow-
der was dissolved in pyridine (160 mL) which was refluxed for
◦
in a Teflon-lined screwcap vial were stirred at 70 C for 24 h. The
2
progress of reaction was monitored by GC–MS. The catalyst was
thoroughly washed with EtOH and hot water before reuse. The
sample was taken from the supernatant after centrifugation. The
1
h. After cooling, the precipitate was collected by filtration and
washed with methanol to give 5,10,15,20-tetrakis(4-nitrophenyl)-
1H,23H-porphyrin as a purple powder in 14% yield. Mn-TNPP was
◦
injector and detector temperature was both set at 260 C in order
◦ ◦ −1
2
to test all the products (TPD: 50 C for 1 min, then 10 C min up to
◦
◦
synthesized after a metallization process of TNPP with MnCl2 in
DMF [29,30].
140 C and 140 C for 15 min). GC was analyzed on a HP 6890 series
GC system, and MS on a 5971A Mass selective Detector.
2.2. Synthesis of azo-CMP-1
2.5. Characterization of catalysts
Mn-TNPP (0.25 g, 0.3 mmol) and p-phenylenediamine (0.065 g,
.6 mmol) were dissolved in DMF (19 mL) in a three-necked round
The IR spectra were recorded on an ABB Bomem FTLA2000-104
spectrometer. X-ray power spectra were recorded using a bruker
0

W. Zhang et al. / Applied Catalysis A: General 489 (2015) 117–122
119
Fig. 2. FT-IR spectra of: TNPP (black line), azo-CMP-1 (red line), azo-CMP-2 (blue
line). (For interpretation of the references to color in this figure legend, the reader
is referred to the web version of this article.)
Fig. 3. Wide-angle XRD patterns of azo-CMP-1 (black line), azo-CMP-2 (red line).
For interpretation of the references to color in this figure legend, the reader is
referred to the web version of this article.)
(
D8-Advance diffractometer with Cu-K␣ radiation. TG of the sam-
ples was recorded using a Mettler TGA/SDTA 851 E analyzer in the
organic framework, then this may provide an ideal system both
to enhance the catalytic activity and to protect the active centers
◦
◦
temperature range 50–800 C at a heating rate of 20 C/min. SEM
measurements were performed on a CamScan CS44 scanning elec-
tron microscope. The samples for TEM observation were suspended
in ethanol and supported on carbon-coated copper. X-ray photo-
electron spectroscopy (XPS) was recorded by a Kratos Ultra DLD
imaging spectrometer (UK) using an Al K␣ Rradiation (1486.6 eV)
in East China University of Science and Technology. The powdered
samples were pressed into pellets prior to the XPS studies.
[
14]. Field-emission scanning electron microscopy (SEM) images
show that azo-CMP-1 was composed of agglomerated plate-shaped
particles (Fig. 4). However, the SEM image showed that the azo-
CMP-2 material was composed of coralline-shaped particles with
smaller size. As expected, the longer length of linker for azo-CMP-
2
, led to a significant distortion during the growth of azo-CMP-2.
Consequently, the azo-CMP-1 heterostructure, favoring ␲–␲ stack-
ing in aggregates, would demonstrate a better performance in
biomimetic catalytic reactions, presumably due to its graphene-like
morphology. Figs. 3 and 4 were results not shown in the bibliogra-
phy.
3
. Results and discussion
3.1. Characterization of catalysts
To elucidate the thermal stability of N N bond, TG/DTG anal-
ysis of azo-CMP-1 and azo-CMP-2 was determined and shown in
Fig. 5. The comparison of azo-CMP-1 and azo-CMP-2 reported in
this work showed that they had almost similar decomposition pro-
The structures of synthesized compounds (azo-CMP-1 and azo-
CMP-2) were characterized in Fig. 2, in order to monitor the
variations in the functional groups. The characteristic stretching
band for N N functionality in the FT-IR spectrum was clearly
◦
files. However, azo-CMP-1 was stable up to 346 C, possessing a
−1
visible at 1447 cm
along with the respective bands for aro-
◦
better thermal stability than azo-CMP-2 (340 C).
matic rings [31]. Additionally, the FT-IR bands located at 1520 and
−
1
1
340 cm
correspond to N O stretching mode, suggesting the
presence of unreacted terminal nitro groups.
3.2. Catalytic activity
Powder XRD analysis of these azo-CMPs revealed no strong
diffraction peaks (Fig. 3), implying that the micro-porous polymers
were composed of an amorphous network. It is pertinent to men-
tion that using pre-synthesized metalloporphyrins building blocks
for CMP formation also resulted in materials without any definite
XRD pattern of monomeric units.
To compare the efficiency of different catalysts, described above,
styrene was used as a model substrate. The kinetic profiles for
the selective oxidation of styrene were represented in Fig. 6. It
can clearly be seen that azo-CMP-1 as catalyst displayed a better
performance than azo-CMP-2. We also noticed that the com-
parably low conversion of styrene epoxides was related with
the low electron density of double bond, which usually reduced
Most recently, a research showed that if the active centers can
be neatly arranged to form a graphene-like 2D porous covalent
Fig. 4. SEM and TEM images of sample azo-CMP-1 (left) and azo-CMP-2 (right).

1
20
W. Zhang et al. / Applied Catalysis A: General 489 (2015) 117–122
double-bond in olefins and the contact between catalyst and sub-
strate. On one hand, the conversions depend on the position and
steric configuration of the double bond, as a result of steric effects
during the epoxidation. On the other hand, the conversions are
decreased by increasing the chain length or the cross-section of
the olefin (1-hexene > cyclohexene). Furthermore, as the length of
linear olefin increases, the mobility of alkene decreases, and there-
fore, the accessibility of active site will be difficult for 1-octane and
1
-dodecene.
The excellent heterogeneous catalysts should not only have high
catalytic activity and selectivity, but should also be structurally sta-
ble and thus be easily recovered for continuous usage. Compound
azo-CMP-1 can be simply recycled by filtration, which was sub-
sequently reused in successive runs. The recycled azo-CMP-1 still
exhibited a very high conversion of 97% and selectivity of >99%
when cyclohexene being used as substrate, thus indicating that
azo-CMP-1 was indeed a heterogeneous catalyst for cyclohexene
epoxidation. The average turnover frequency (TOF) in the first 12 h
was also listed in Table 1.
Fig. 5. TG/DTG curves for sample azo-CMP-1 (left) and azo-CMP-2 (right).
With the aim at excluding any possible contamination by homo-
geneous metal active sites responsible for observed catalyst activity
and selectivity, a hot filtration test in azo-CMP-1 have been per-
formed shown in Fig. 7. Accordingly, the oxidation was allowed
to proceed for 90 min before being split into two fractions, one
containing the suspended catalyst and the other being filtered to
remove any solid precipitate. The former solution was kept to react
with additional azo-CMP-1 catalyst. For the latter one, the cata-
lyst was separated and discarded form the reaction mixture. Then,
the supernatant was analyzed by GC test. Finally, the conversion of
first fraction did well with the result of solution containing cata-
lyst all through. And, the catalytic performance of latter oxidation
increased slightly. Altogether, this hot filtration test confirmed a
truly heterogeneous process.
Fig. 6. Plot of conversion versus time with different substrates and catalysts.
Some benchmarking of azo-CMP-1 has been carried out by com-
parison with well known and readily available catalysts. Table 2
contains the epoxidation of trans-stilbene studies in the previous
literature. Based on the performance of azo-CMP-1 and homoge-
nous catalysts toward the trans-stilbene epoxidation, azo-CMP-1
outperformed the 2D layered in epoxidation via its structural resis-
tance to formation of catalytically inactive species.
their nucleophilicity toward electrophilic oxygen of catalytic
intermediate-porphyrin-Mn(V) O [30].
The catalytic activity of cyclohexene showed a higher conver-
sion than cyclooctene. The steric hindrance should be attributed to
this result. The size of cyclohexene was smaller than cyclooctene.
Consequently, it was hard for cyclooctene to be accessible to
active sites. Moreover, we also viewed recent published works
about epoxidation of cyclohexene and cyclooctene by metal met-
alloporphyrinic framework catalyst, the results showed that the
conversion of cyclohexene was higher than that of cyclooctene
3.3. Catalytic behavior study
Although the successive catalytic runs (Table 1, entry 2) and
comparison with ever reported catalysts (Table 2) have evidenced
that CMP strategy could prevent the self-dimerization of porphyrin
centers by bimolecular interaction to form the M-O-O-M unit
[35,4], porphyrinic networks constructed via Yamamoto homo-
coupling reaction usually exhibit strong hydrophobicity with a
[
10,32]. Although the cyclohexene was usually considered
in the bibliography as more difficult to oxidized than cyclooctene,
the rigorous dimension of channel size within catalyst has become
the main factor that affects the conversion of substrate with simi-
lar structure. This observation highlighted that azo-CMP-1 offered
channels with accessible catalytic sites for the substrates, which
greatly facilitated their diffusion.
◦
water contact angle about 135 [36]. This property greatly increases
the diffusion resistance by restricting exposing catalytically active
sites to those reactants with hydrophilic properties. However, if
there was no hydrophobic properties, the by-product of TBHP-
tertiary butanol in epoxidation would coordinate with Mn sites.
Therefore, a moderate hydrophobic property should facilitate the
catalytic application. Interestingly, N N bond endowed the
porphyrinic polymers (azo-CMP-1 and azo-CMP-2) with a rare
amphipathic property (Fig. 8). Thus, we supposed that azo-CMPs
catalysts could provide a desirable micro-environment for selec-
tive oxidation, facilitating the spread of reactants and accordingly
enhancing the overall catalytic performance.
Although the graphene-like morphology of azo-CMP-1 could
interpret its superior catalytic activity to azo-CMP-2, the nature of
Mn sites in azo-CMPs has not been revealed. To identify this point,
XPS analysis can help to reveal the oxidant state of Mn sites of
molecules in azo-CMPs. As shown in Fig. 9, one may notice that the
To further confirm aforementioned claim, we compared the cat-
alytic activities of azo-CMP-1 with their molecular components of
MnCl and Mn-TNPP shown in Table 1. MnCl showed a lower cat-
2
2
alytic activity with conversions of 57%. In comparison, Mn-TNPP
did show quite moderate catalytic activity that could transform
8
6% of the cyclohexene into the cyclohexene oxide, but still were
not as efficient as heterogeneous azo-CMP-1 (100% conversion). In
order to understand the steric effect on catalytic efficiency, a range
of natural alkenes were selected to be oxidized in this catalytic
system, including linear alkenes, styrene and trans-stilbene. Over-
all, increasing the steric size of alkenes triggered lower catalytic
activity.
From the catalytic results, it was obvious that the conver-
sion of cyclic olefin was higher than the linear olefin. With this
regard, we began to address this from two points: the position of

W. Zhang et al. / Applied Catalysis A: General 489 (2015) 117–122
121
Table 1
Scope of azo-CMPs catalyzed epoxidation of alkenes .
a
Entry
Substrate
Catalyst
Conversion (%)b
79
Selectivity (%)c
>99
TOFh
1
azo-CMP-1
6.6
8.3
2
azo-CMP-1
100/97d
>99
3
4
azo-CMP-1
azo-CMP-1
58
35
>99
>99
4.8
2.9
5
6
azo-CMP-1
azo-CMP-1
azo-CMP-2
82
31
69
68e
50f
65e
4.6
1.3
5.7
7
8
MnCl2
57
86
78g
53g
3.7
3.8
9
Mn-TNPP
a
Olefin (500 mM), TBHP (1000 mM), catalyst (0.01 mmol, 5 mM), acetonitrile (3.0 mL) sealed and bromobenzene as internal standard in a Teflon-lined screwcap vial were
◦
stirred at 70 C for 24 h.
b
Conversion [%].
c
d
e
f
◦
◦
−1
◦
◦
Selectivity [%] were determined by GC using an SE-54 column (50 C for 1 min, then 10 C min up to 140 C and 140 C for 15 min).
After fifth cycles.
Benzaldehyde and phenylacetaldehyde.
Benzaldehyde.
g
h
2
-Cyclohexene-1-ol and 2-cyclohexene-1-one.
The TOF was defined as mmol of product per mmol of catalyst per hour.
peak value of Mn2p3/2 shifted to a higher value (642.6 eV for azo-
CMP-1) compared to the binding energy of Mn(III) in azo-CMP-2
after being assembled into extended ␲ systems, that is, a charge
transfer was induced from Mn(III) center to linkers, especially
for azo-CMP-1. Therefore, the catalytic ability of Mn(III) center in
azo-CMPs can be greatly enhanced due to such a desirable catalysis-
promoted electronic environment.
Interestingly, there was a satellite peak at 654.2 and 653.4 eV,
respectively, beside the main peak of Mn2p3/2 in azo-CMPs. The
resulting satellite peak could be attributed to the manganese-oxo
species from catalyst. Furthermore, the Mn sites of azo-CMP series
were easily activated. Hence, our reported azo-CMP series had a
strongly biomimetic characteristic.
(
642.3 eV). In a previous study, the reported 642.2 eV of Mn-TPP
also was close to the Mn2p3/2 value of azo-CMPs [30,33,37–39].
While, the peak value of Mn2p3/2 for azo-CMP-1 and azo-CMP-2
both shifted to higher value, relative to Mn-TPP. Then, it can be con-
cluded that the redox property of the Mn complexes was changed
Table 2
Catalytic activities toward the homogenous oxidation of trans-stilbene of some pre-
viously reported catalyst.
Catalyst
Conversion (%)
Yield (%)
TOF
This work
31
96
24
87
9
15
58
7
71
5
1.3
69
15
59
4.2
0
MMPF-3 [11]
PPF-1Co [11]
MMPF-5(Co) [12]
MMPF-5 [12]
Fe(TMP)Cl [33]
Au/TiO2 [34]
Trace
95
Trace
71
3.0
Fig. 7. Conversion of cyclohexene into epoxide based on a hot filtration test.

1
22
W. Zhang et al. / Applied Catalysis A: General 489 (2015) 117–122
Acknowledgments
Special thanks to Dr. Liu from East China University of Science
and Technology for his help on testing of XPS data. This work
was supported financially by the National “Twelfth Five-Year” Plan
for Science & Technology (2012BAD32B03), the National Natural
Science Foundation of China (20903048) and the Innovation Foun-
dation in Jiangsu Province of China (BY2013015-10).
References
[
[
[
[
[
1] M. Zhao, S. Ou, C.D. Wu, Acc. Chem. Res. 47 (2014) 1199–1207.
2] M. Costas, Coord. Chem. Rev. 255 (2011) 2912–2932.
3] P.R. Ortiz de Montellano, Chem. Rev. 110 (2010) 932–948.
4] T.C. Bruice, Acc. Chem. Res. 24 (1991) 243–249.
5] T. Xue, S. Jiang, Y. Qu, Q. Su, R. Cheng, S. Dubin, C.-Y. Chiu, R. Kaner, Y. Huang,
X. Duan, Angew. Chem. Int. Ed. 51 (2012) 3822–3825.
[
6] M. Shema-Mizrachi, G.M. Pavan, E. Levin, A. Danani, N.G. Lemcoff, J. Am. Chem.
Soc. 133 (2011) 14359–14367.
7] M.H. Xie, X.L. Yang, C.D. Wu, Chem. Commun. 47 (2011) 5521–5523.
8] M.H. Xie, X.L. Yang, Y. He, J. Zhang, B. Chen, C.D. Wu, Chem. Eur. J. 19 (2013)
Fig. 8. Contact angle for a droplet of (a) water on azo-CMP-1, (b) water on azo-CMP-
2
, (c) oil on azo-CMP-1 and (d) oil on azo-CMP-2.
[
[
14316–14321.
[
9] X.L. Yang, C. Zou, Y. He, M. Zhao, B. Chen, S. Xiang, M. O’Keeffe, C.D. Wu, Chem.
Eur. J. 20 (2014) 1447–1452.
[
[
[
[
[
10] C. Zou, T. Zhang, M.H. Xie, L. Yan, G.Q. Kong, X.L. Yang, A. Ma, C.D. Wu, Inorg.
Chem. 52 (2013) 3620–3626.
11] L. Meng, Q. Cheng, C. Kim, W.Y. Gao, L. Wojtas, Y.S. Chen, M.J. Zaworotko, X.P.
Zhang, S. Ma, Angew. Chem. Int. Ed. 51 (2012) 10082–10085.
12] X.-S. Wang, M. Chrzanowski, L. Wojtas, Y.-S. Chen, S. Ma, Chem. Eur. J. 19 (2013)
3
297–3301.
13] B. Li, Y. Zhang, D. Ma, T. Ma, Z. Shi, S. Ma, J. Am. Chem. Soc. 136 (2014)
202–1205.
14] X.-S. Wang, M. Chrzanowski, D. Yuan, B.S. Sweeting, S. Ma, Chem. Mater. 26
2014) 1639–1644.
1
(
[
[
15] X. Feng, L. Chen, Y. Dong, D. Jiang, Chem. Commun. 47 (2011) 1979–1981.
16] S. Kandambeth, D.B. Shinde, M.K. Panda, B. Lukose, T. Heine, R. Banerjee, Angew.
Chem. Int. Ed. 52 (2013) 13052–13056.
[
[
17] L. Chen, Y. Yang, Z. Guo, D. Jiang, Adv. Mater. 23 (2011) 3149–3154.
18] P.M. Budd, B. Ghanem, K. Msayib, N.B. McKeown, C. Tattershall, J. Mater. Chem.
13 (2003) 2721–2726.
[
19] R.K. Totten, Y.S. Kim, M.H. Weston, O.K. Farha, J.T. Hupp, S.T. Nguyen, J. Am.
Chem. Soc. 135 (2013) 11720–11723.
[
[
[
[
[
20] P. Kaur, J.T. Hupp, S.T. Nguyen, ACS Catal. 1 (2011) 819–835.
21] H. Ma, H. Ren, S. Meng, F. Sun, G. Zhu, Sci. Rep. 3 (2013) 2611.
22] A.M. Shultz, O.K. Farha, J.T. Hupp, S.T. Nguyen, Chem. Sci. 2 (2011) 686–689.
23] O.L. Hollis, Anal. Chem. 38 (1966) 309–316.
24] H.A. Patel, S.H. Je, J. Park, Y. Jung, A. Coskun, C.T. Yavuz, Chem. Eur. J. 20 (2014)
772–780.
Fig. 9. XPS spectra for the clean azo-CMPs surface, Mn 2p region.
4
. Conclusions
[
25] H.A. Patel, S.H. Je, J. Park, D.P. Chen, Y. Jung, C.T. Yavuz, A. Coskun, Nat. Commun.
4
(2013) 1357–1364.
Two efficient catalysts azo-CMP-1 and azo-CMP-2 were suc-
[
[
26] S. Braese, T. Muller, RSC Adv. 4 (2013) 6886–6907.
27] L. Li, H. Zhao, J. Wang, R. Wang, ACS Nano 8 (2014) 5352–5364.
cessfully constructed with meso-tetra (4-nitrophenyl)porphyrin as
building blocks via azo ( N N ) linkage. An excellent performance
with 100% conversion and no less than 99% selectivity for cyclohex-
ene was obtained, when azo-CMP-1 was employed as catalyst. On
the other hand, various of other unsaturated olefins with differ-
ent steric sizes were investigated to confirm the catalytically active
sites being located into the channels of catalysts. Contact angle
research showed that azo linkage endowed azo-CMPs with a rare
amphipathic property, which was essential to the reactant diffusion
during the catalytic process. The SEM photos together with XPS
study, both evidenced azo-CMP-1 with a superior catalytic activ-
ity, with respect to azo-CMP-2. Therefore, our reported strategy
assembling metalloporphyrins into extended ␲ materials linked
by azo bonds, provided a promising platform to design functional
polymers as catalysts in selective oxidation.
[28] M. Yuasa, K. Oyaizu, A. Yamaguchi, M. Kuwakado, J. Am. Chem. Soc. 126 (2004)
1128–11129.
1
[
[
29] A.D. Adler, J. Inorg. Nucl. Chem. 32 (1970) 2443–2445.
30] W. Zhang, P. Jiang, Y. Wang, J. Zhang, J. Zheng, P. Zhang, Chem. Eng. J. 257 (2014)
28–35.
31] L.M. Sáiz, P.A. Oyanguren, M.J. Galante, React. Funct. Polym. 72 (2012) 478–485.
32] X.L. Yang, C.D. Wu, Inorg. Chem. 53 (2014) 4797–4799.
33] W. Nam, J. Inorg. Biochem. 80 (2000) 219–225.
[
[
[
[34] P. Lignier, F. Morfin, S. Mangematin, L. Massin, J.L. Rousset, V. Caps, Chem.
Commun. (2007) 186–188.
[
35] C.G. Bezzu, M. Helliwell, J.E. Warren, D.R. Allan, N.B. McKeown, Science 327
2010) 1627–1630.
(
[36] X.S. Wang, J. Liu, J.M. Bonefont, D.Q. Yuan, P.K. Thallapally, S. Ma, Chem. Com-
mun. 49 (2013) 1533–1535.
37] J. Xie, Y.J. Wang, Y. Wei, Catal. Commun. 11 (2009) 110–113.
38] B.E. Murphy, S.A. Krasnikov, N.N. Sergeeva, A.A. Cafolla, A.B. Preobrajenski, A.N.
Chaika, O. Lubben, I.V. Shvets, ACS Nano 8 (2014) 5190–5198.
[
[
[39] A. Kaplan, E. Korin, A. Bettelheim, Eur. J. Inorg. Chem. 2014 (2014) 2288–2295.