Novel organic polymerinorganic hybrid material zinc poly(styrene- phenylvinylphosphonate)-phosphate prepared with a simple method

Article abstract of DOI:10.1016/j.jssc.2011.06.026

A novel type of organic polymerinorganic hybrid material layered crystalline zinc poly(styrene-phenylvinylphosphonate)-phosphate (ZnPS-PVPP) was synthesized under mild conditions in the absence of any template. And the ZnPS-PVPP were characterized by FT-I

Full text of DOI:10.1016/j.jssc.2011.06.026

Journal of Solid State Chemistry 184 (2011) 2605–2609
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Novel organic polymer–inorganic hybrid material zinc poly
(styrene-phenylvinylphosphonate)-phosphate prepared with
a simple method
Jing Huang, Xiangkai Fu n, Gang Wang, Qiang Miao
College of Chemistry and Chemical Engineering Southwest University, Research Institute of Applied Chemistry Southwest University, The Key Laboratory of Applied Chemistry of
Chongqing Municipality, The Key Laboratory of Eco-environments in Three Gorges Reservoir Region Ministry of Education, Chongqing 400715, China
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel type of organic polymer–inorganic hybrid material layered crystalline zinc poly(styrene-
phenylvinylphosphonate)-phosphate (ZnPS-PVPP) was synthesized under mild conditions in the
absence of any template. And the ZnPS-PVPP were characterized by FT-IR, diffusion reflection
UV–vis, AAS, N2 volumetric adsorption, SEM, TEM and TG. Notably, this method was entirely different
from the traditional means used for preparing other zinc phosphonate. Moreover, it could be deduced
that ZnPS-PVPP possessed the potential applications for catalyst supports. In the initial catalytic tests,
the catalysts immobilized onto ZnPS-PVPP showed comparable or higher activity and enantioselectivity
with that of catalysts reported by our group in the asymmetric epoxidation of unfunctional olefins.
& 2011 Elsevier Inc. All rights reserved.
Received 21 February 2011
Received in revised form
12 June 2011
Accepted 23 June 2011
Available online 3 July 2011
Keywords:
Asymmetric catalysis
Copolymerization
Heterogeneous catalysis
Mesoporous materials
Supported catalysis
1. Introduction
which all could be modified by diamine, polyamine, sulfoalkyl or
diphenoxyl and used for immobilization of chiral salen Mn(III)
Metal phosphonate chemistry has attracted considerable
attention in recent years because of their versatile framework
topologies as well as their potential applications in the areas of
catalysis, ion exchange, photochemistry and materials chemistry
[1,2]. The layered phosphonates attract special interests due to
their unique properties, such as their high thermal stability and
versatility of organic functional groups that could be intro-
duced [3]. Originally, work in this area was focused on group IV
metal phosphonates [4]. Consequently, research in the zirconium
phosphates and zirconium phosphonates field is active, which
have involved many aspects such as intercalation chemistry [5,6]
and proton conductivity [7].
In the previous works, our groups have reported a series
of organic–inorganic hybrid zirconium phosphonate–phosphates
Zr(HPO4)2ꢀx(O3P–G)x ꢁ nH2O (x¼0–2, G is organic groups) as various
kinds of catalysts or catalyst supports, such as zirconium [N-(phos-
phonomethyl)iminodiacetic acid-phosphate] Zr(HPO4) [O3PCH2N
(CH2COOH)2]ꢁ nH2O. Subsequently, in order to modulate for the
immobilization of homogeneous chiral Salen Mn (III), our group have
spent many efforts on these in the last decades such as the synthesis
of zirconium oligostyrenylphosphonate–phosphate (ZSPP) and zirco-
nium poly (styrene-phenylvinylphosphonate)-phosphate (ZPS-PVPA),
complexes through axial coordination. The immobilized catalysts
effectively catalyzed epoxidation of styrene and -methylstyrene
a
(ee, 50–78% and 86 to 499%) with m-CPBA or NaClO. These results
were significantly better than those achieved with the homogeneous
catalyst under the same reaction conditions (ee, 47% and 65%). At the
same time, the immobilized catalysts could be reused at least ten
times without significant loss of activity and enantioselectivity [8,9].
Furthermore, as far as we are aware, few attempts have previously
been made in organic–inorganic hybrid zinc phosphonate–phosphate
as catalyst supports, even less on organic polymer–inorganic hybrid
zinc phosphonate–phosphate applied for the immobilization of chiral
salen Mn (III). In this work, ZnPS-PVPP 1–7 were prepared (shown in
Scheme 1) from the copolymer of styrene-phenylvinylphosphonic
acid with zinc acetate dihydrate and sodium dihydrogen phosphate
treated with different ratios of phosphate and phosphonate. Delight-
edly, the immobilized catalyst on ZnPS-PVPP showed compa-
rative activity and enantioselectivity with that of catalysts on ZSPP
or ZPS-PVPA in the primary tests.
The question as to whether or not layered and crystalline zinc
phosphonate–phosphates hybrid materials could also be synthe-
sized without addition of template is examined here. Unexpect-
edly, layered and crystalline ZnPS-PVPP 1–7 were obtained in the
terms of 66 1C and THF-water as solvent in the absence of any
template. The main advantage in the synthesis of ZnPS-PVPP 1–7
lies in that this method is simple, cost-effective and environmen-
tally friendly. Moreover, the strategy is obviously different from
n Corresponding author. Fax: þ86 23 68254000.
E-mail address: fxk@swu.edu.cn (X. Fu).
0022-4596/$ - see front matter & 2011 Elsevier Inc. All rights reserved.
doi:10.1016/j.jssc.2011.06.026

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J. Huang et al. / Journal of Solid State Chemistry 184 (2011) 2605–2609
that traditional tactics, which are usually taken the direct reaction
of phosphonic acid with metal source by the hydrothermal
method, or by heating to reflux appropriate solutions, or by
making metal salts contact with molten phosphonic acid.
copolymer as literature [8] yield 7.52 g. GPC: Mn¼38,608,
m¼38, n¼8, Mw/Mn¼2.
2.2. Preparation of zinc poly(styrene-phenylvinylphosphonate)-
phosphate (ZnPS-PVPP)
2. Experimental
PS-PVPA (1.0 g, 1 mmol) was dissolved in 100 mL THF at room
temperature for 30 min. Sodium dihydrogen phosphate (0.62 g,
4 mmol) in 4 mL of deionized water was added and then zinc
acetate (1.1 g, 5 mmol) in 5 mL of deionized water was added
dropwise and kept on stirring. Consequently, the temperature
was raised to 66 1C step by step. The reaction mixture was kept at
66 1C for 72 h and then laid for another 18 h at room temperature.
After Et3N (0.68 g, 6.7 mmol) was added and stirred for 30 min,
the solvent was evaporated under reduced pressure. The ivory
yellow solid zinc poly (styrene-phenylvinylphosphonate)-phos-
phate 1 was filtered, washed with deionized water and dried at
60 1C for 24 h in vacuum. Ivory yellow ZnPS-PVPP 2–7 were
prepared according to the same procedure. IR (KBr):vmax/cmꢀ1
3059, 3028, 2923 (CH), 1686, 1493, 1453, 756, 698 (ꢀC6H5), 1027
(PQO). ZnPS-PVPP 3: Found: C, 58.08; H, 4.97. Calc. for
2.1. Synthesis of styrene-phenylvinylphosphonic acid copolymer
(PS-PVPA)
1-Phenylvinyl phosphonic acid (PVPA) was synthesized accord-
ing to literature [10] and its structures were confirmed by 1H
NMR, 31P NMR and FT-IR. 1H NMR (CDCl3): 6.06 (d, 1H), 6.23
(d, 1H), 7.26–7.33 (m, 3H), 7.48 (m, 2H). 31P NMR (CD3OD): 15.9.
IR (KBr): 2710, 2240, 1500, 1200, 1040, 950, 780, 720, 700 cmꢀ1
1-Phenylvinylphosphonic acid (4 g, 21.7 mmol), styrene
(20 mL, 173.9 mmol), ethyl acetate (150 mL) and benzoyl peroxide
(BPO, 1.0 g, 4.7 mmol) were used for preparation of PS-PVPA
.
C72H73O11P3Na2Zn3: C, 59.71; H, 5.04%.
PO3H2
BPO
2.3. Synthesis of the supported catalyst (Scheme 2)
2.3.1. Synthesis of chloromethyl-zinc poly(styrene-
PO3H2
phenylvinylphosphonate)-phosphate (ZnCMPS-PVPP)
H2
C
H2
C
2H2O
(CH3COO)2Zn
NaH2PO4
H
C
Chloromethyl methyl ether (9.3 mL), anhydrous zinc chloride
(3.32 g, 24.34 mmol) and ZnPS-PVPP (5.0 g, 3.4 mmol) were
mixed in 40 mL chloroform and stirred at 40 1C for 10 h. After
cooling down, sodium carbonate saturated solution was added to
neutralize the mixture, and the solvent was evaporated. The
product was filtered, washed with deionized water and dried
in vacuo to obtain ZnCMPS-PVPP (5.84 g, 90.1%). IR (KBr):
vmax/cmꢀ1 3026, 2925 (CH), 2341(OQP–OH), 1650, 1542, 1510,
1493 (ꢀC6H5), 1267 (PQO), 700 (C–Cl) cmꢀ1. Found: C, 51.16; H,
4.09%. Calc. for C80H81O11P3Cl8Na2Zn3: C, 52.31; H, 4.41%.
*
C
n
m
PO3
H2
C
H2
C
H
C
Zn(NaPO4)(1-x)
yH2O
*
C
n
4
x
2.3.2. Synthesis of arylaminomethyl-zinc poly
1
2
3
5
6
7
1
(styrene-phenylvinylphosphonate)-phosphate (ZnAMPS-PVPP)
Proportional amount of aryldiamine p-phenylenediamine was
blended with ZnAMPS-PVPP (1 g), Na2CO3 (1.06 g, 0.01 mol), CuI
(0.2 g, 1 mmol) and alcohol 50 mL, and the mixture was stirred
and kept at 70 1C for 12 h. Subsequently, the mixture was
neutralized and the solvent was vaporized. Then, the product
was filtered, washed and dried in vacuo. Reaction yield always
x
y
0.2 0.25 0.33 0.4 0.5 0.75
3.1 2.8 2.7 2.6 2.5 2.4 2.2
Scheme 1. Synthesis of ZnPS-PVPP 1–7.
Na2CO3
CH3OCH2Cl
N
H
NH2
CH2Cl
ZnCMPS-PVPP
ZnPS-PVPP
ZnCl2
H2N
NH2
ZnAMPS-PVPP
(
ZnPS-PVPP )
=
N
O
N
O
Mn
t-Bu
t-Bu
Salen Mn (III)Cl
reflux
NH
t-Bu
t-Bu
Et3N
THF
HN
Scheme 2. Synthesis of the supported catalyst.

J. Huang et al. / Journal of Solid State Chemistry 184 (2011) 2605–2609
2607
exceeded 90%. Found: C, 61.15; H, 5.02; N, 9.05. Calc. for
C128H137N16O11P3Na2Zn3: C, 63.81; H, 5.69; N, 9.31%.
Moreover, the melting point of the samples increased with the
ratio of phosphate in the samples. While for the catalyst,
the organic moieties decomposed in the scope of 200–850 1C.
The total weight loss was found to be 69.32%. Obviously, catalyst
still kept high stability lower than 200 1C. Generally, organic
reactions of heterogeneous catalysis were carried out below
200 1C, so both the products and the catalyst had enough thermal
stability to be applied in heterogeneous catalytic reactions.
As described in Fig. S3, the XRD patterns of ZnPS-PVPP
displayed a broad 001 peak (the lowest-angle diffraction peak in
the pattern), accompanied with other peaks at higher-order 00n
peaks at larger angles and lower intensities such as at 38.041.
Therefore, it could be deduced that ZnPS-PVPP 1–7 were in
crystalline states and all could be applied as mesoporous materi-
als. Shown in Fig. S3, the parts of inorganic phosphate in ZnPS-
PVPP 1–6 contributed to the similarity of XRD patterns of samples
1–6 at the vicinity of 24.81 to that of Zn3(PO4)2. Furthermore, XRD
patterns of ZnPS-PVPP 1–6 close to 201 and 37.921 were nearly
identical to that of ZnPS-PVPP 7. They were originated in the
sections of zinc poly(styrene-phenylvinylphosphonate) in ZnPS-
PVPP samples 1–6. Therefore, conclusion could be obtained that
ZnPS-PVPP 1–6 were not the mixture of zinc polystyrene-phe-
nylvinylphosphonate and zinc inorganic phosphate but the zinc
poly(styrenephenylvinylphosphonate)-phosphate hybrid materi-
als. Simultaneously, the interlayer distances of ZnPS-PVPP 1–7
2.3.3. Synthesis grafting chiral salen Mn(III) catalyst onto
ZnAMPS-PVPP
Chiral salen Mn(III) (4 mmol) in 10 mL of THF was added
dropwise to the solution of ZnAMPS-PVPP (0.5 g) pre-swelled in
THF for 30 min and Et3N (5 mmol) and was stirred for 10 h under
reflux. Then the solution was neutralized and the solvent was
removed. The dark brown powder was obtained by filtration and
washed with CH2Cl2 and water until no Mn could be detected by
AAS. The amount of Mn (salen) anchored onto ZnPS-PVPP is
0.72 mmol/g ascertained by AAS based on Mn element. Found:
C, 69.15; H, 7.01; N, 2.91%. Calc. for C416H545N32O27P3Na2Zn3Mn8:
C, 71.65; H, 7.82; N, 3.22%.
2.4. Chemical analysis
In a white porcelain crucible, a sample of 50 mg ZnPS-PVPP
3 was put in it and was heated up to 700 1C for 5 h in Muffle
furnace. Due to the high temperature, ZnPS-PVPP 3 decomposed.
Then 20 mL of hydrochloric acid (1:1) was added to the porcelain
crucible and was heated to boiling for 30 m on the electric
furnace. In the resulting solution, the sodium content was
determined by AAS.
˚
were almost 11 A broader than that of Zn3(PO4)2. It could be
inferred that the styrene-phenylvinylphosphonic acid copolymer
chain introduced in ZnPS-PVPP made the zinc layer stretched and
became broader (Fig. 1). The exact structure of it should be
affirmed in the future.
2.5. Asymmetric epoxidation
The activity of the prepared catalysts were tested for the
epoxidation of unfunctionalized olefins in CH2Cl2 at ꢀ40 1C for
5 h using m-CPBA/NMO as oxidant and with 5 mol% of the
catalysts. After reaction, Na2CO3 (4 mL, 1.0 M) was added to
quench the reaction.
The surface area of ZnPS-PVPP 3 (Fig. 2), measured by the BET
nitrogen adsorption method (Micromeritics Gemini) after
removal of the surfactant, reached 4.9 m2 gꢀ1 with a pore size
of 3.5 nm and a pore volume of 1.3 ꢂ 10–2 mL gꢀ1. On the other
hand, the size of solvated Mn (salen)Cl complex was estimated to
be 2.05–1.61 nm by MM2 based on the minimized energy [11].
Herein, ZnPS-PVPP 3 could provide enough room to accommodate
the solvated chiral Mn (III) salen complex as well as that the local
environment inside the mesopores and pore size of the support
did affect the enantioselectivity of the epoxidation reaction. It
was the crucial property that ZnPS-PVPP could be used as catalyst
supports. Furthermore, the frameworks of ZnPS-PVPP could be
easily designed and assembled to generate pores or channels of
various sizes and shapes by appropriate modification of the
styrene-phenylvinylphosphonic acid copolymer chain (Fig. 3).
Maybe the excellent catalytic effect be induced by the special
structures of ZnPS-PVPP.
3. Results and discussion
Na content of ZnPS-PVPP 3. The sodium content in ZnPS-PVPP
3 was 1.7%, which was 0.2% lower than that of theoretical values;
this can probably be attributed to the surface-bound or inter-
calated water leading to the augment of the molecular weight.
FT-IR spectra (Fig. S1 in supporting Information) were in good
agreement with the expected chemical structure of the organic
moieties. In particular the formation of ZnPS-PVPP was confirmed
by prominent bands at 1145, 1089, and 986 cmꢀ1, which were
attributed to R-PO23ꢀ phosphonate stretching vibrations, and by
the adsorptions at 1201, 1144, and 1077 cmꢀ1, which were due to
the phosphonate and phosphate stretching vibrations. The FT-IR
spectra confirmed that ZnPS-PVPP were prepared successfully.
Meanwhile, shown in Fig. S1, the most informative evidence
confirmed the anchoring of the chiral salen–Mn–Cl to the aryl-
diamine modified ZnPS-PVPP. The azomethene(CQN) stretching
band of salen–Mn–Cl appeared at 1612 cmꢀ1 (9 in Fig. S1). While
for the supported catalyst, this band was also observed at the
vicinity of 1613 cmꢀ1. The heterogenous catalyst and salen–Mn–
Cl had shown the same band at 1638 cmꢀ1 attributed to the
The morphology of the surface of ZnPS-PVPP (Fig. 4), obtained
from SEM measurement, indicated that there were regular neat
vibration of imine group. The stretching vibration at 1030 cmꢀ1
,
which was assigned to characteristic vibrations of the phosphonic
acid group in ZnPS-PVPP was obviously weakened due to
the electronic structure changes for the host–guest interaction.
Moreover, an additional band around 3408 cmꢀ1 was observed
for the catalyst, which was assigned to the stretching vibration of
N–H groups.
From the TG curves (Fig. S2), it could be inferred that the sharp
weight loss was 54.58% with the decomposition of the appended
organic fragments in the temperature range of 200–600 1C.
Fig. 1. Hypothesized layered structure of ZnPS-PVPP 3.

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J. Huang et al. / Journal of Solid State Chemistry 184 (2011) 2605–2609
Fig. 2. Cross sections of the x¼0.25, 0.33 and 0.5.
Fig. 4. (A) SEM image of layered ZnPS-PVPP 3; and (B) TEM images of the layered
ZnPS-PVPP 3.
symmetric epoxidation of unfunctionalized olefins, which might
induce the excellent catalytic activities and properties of the
heterogeneous chiral catalysts.
The diffuse reflectance UV–vis spectrum for the ZnPS-PVPP
(Fig. S4) showed a strong absorption around 227 nm, which could
be assigned to the
p–p* transition of the phenyl groups. There
Fig. 3. Nitrogen adsorption–desorption isotherm and pore distribution of
ZnPS-PVPP 3.
was another strong absorption around 326 nm, which was origi-
nated in the involvement of the charge transfer transitions from
the O atoms of the phosphate or phosphonate to the empty 4s
orbitals of the Zn2þ ions. Therefore, it could be deduced that the
samples might be applied in the field of shielding UV, such as
sunscreen creams. Further investigations were in progress. On the
other hand, according to salen–Mn–Cl, the bands at 334 nm could
be attributed to the charge transfer transition of salen ligand; the
band at 435 nm was due to the ligand-to-metal charge transfer
transition; the band at 510 nm was assigned to the d–d transition
of Mn(III) salen system. While for the heterogenerous catalysts,
all the characteristic bands appeared in their spectra but the
immobilized salen Mn(III) catalysts exhibited a blue shift from
334, 435 and 510 nm to 330, 427 and 503 nm, which indicated
that an interaction existed between the salen Mn(III) complex and
the aryldiamine modified ZnPS-PVPP.
plate layers, which were mainly aggregation of the parts of
zinc inorganic phosphate in ZnPS-PVPP; while the anomalous
suborbicular segments were congregation of proportion of zinc
poly(styrene-phenylvinylphosphonate) in ZnPS-PVPP. Meanwhile,
the supports were various caves, holes, porous and channels with
different shape and size were existed in every particles. Some
micropores and secondary channels would increase the surface
area of the catalyst and provide enough chance for substrates to
access to the catalytic active sites. The TEM photography of the
ZnPS-PVPP (Fig. 4) displayed that the structure of the support was
spheroid, its channels, holes and cavums could be observed
clearly, and their sizes were about 70–80 nm, as well as the
average diameter of these secondary channels among the layers
of the supports were around 50–60 nm. Based on the interlayer
spacings of the sample determined by XPRD, it could be deduced
that each particle was made up of stacks of 25–30 layers of the
sample, leading to few mesopores with the average dimensions
of 3.5 nm. So the supports could provide enough space for
The activity of the prepared catalyst immobilized chiral salen–
Mn–Cl onto ZnPS-PVPP was tested for the epoxidation of
a
-methylstyrene and indene in CH2Cl2 at ꢀ20 1C for 6 h using
m-CPBA/NMO as oxidant and with 5 mol% of the catalyst. The
conversion and ee values of the epoxide were determined by GC.

J. Huang et al. / Journal of Solid State Chemistry 184 (2011) 2605–2609
2609
Table 1
Medium Enterprise Technology (NO.09C26215112399) and
National Ministry of Human Resources and Social Security Start-
up Support Projects for Students Returned to Business, Office of
Human Resources and Social Security Issued 2009 (143).
Asymmetric epoxidation of
neous catalysts with m-CPBA/NMOa as oxidant systems.
a-methylstyrene and indene catalyzed by heteroge-
Entry
Substrate
Catalyst
Time
Con. (%)
Ee (%)
1
2
3
4
a
-Methyl styrene
A
A
B
B
6
6
6
6
499
499
62
499
499
59
Appendix A. Supplementary materials
Indene
Indene
a-Methyl styrene
56
18
Supplementary data associated with this article can be found
in the online version at doi:10.1016/j.jssc.2011.06.026.
A¼the immobilized chiral salen Mn (III) catalysts on p-phenylenediamine mod-
ified ZnPS-PVPP;
B¼the immobilized chiral salen Mn (III) catalysts on p-phenylenediamine mod-
ified ZPS-IPPA.
a
References
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(5 mol%) and m-CPBA (2 mmol). The conversion and the ee value were determined
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4. Conclusions
In summary, this work demonstrated that layered crystalline
inorganic–organic polymer hybrid materials ZnPS-PVPP could be
synthesized under mild conditions and the catalyst immobilized
chiral salen Mn (III) onto ZnPS-PVPP showed obviously superior
activity and enantioselectivity.
Acknowledgments
This work was financially supported by National Ministry of
Science and Technology Innovation Fund for High-tech Small and