A new, facile method to prepare hybrid calcium poly(styrene-phenylvinylphosphonate)-phosphate materials for a superior performance catalyst support

Article abstract of DOI:10.1039/c4ra04299a

A simple and facile route is developed to synthesize a new type of calcium poly(styrene-phenylvinylphosphosphonate)-phosphate (CaPS-PVPA). Structure analysis reveals that CaPS-PVPA is a layered crystalline mesoporous material and could have potential appl

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A new, facile method to prepare hybrid calcium
poly(styrene-phenylvinylphosphonate)–phosphate
Cite this: RSC Adv., 2014, 4, 46498
materials for a superior performance catalyst
support†
Received 14th May 2014
Accepted 7th August 2014
ab
Jing Huang,abc Mei Tangab and Chang Ming Li
*
DOI: 10.1039/c4ra04299a
www.rsc.org/advances
A simple and facile route is developed to synthesize a new type of instance zirconium oligo-styrenylphosphonate-phosphate
calcium poly(styrene-phenylvinylphosphosphonate)–phosphate (ZSPP), zirconium poly (styrene-isopropenylphosphonate)-
(CaPS-PVPA). Structure analysis reveals that CaPS-PVPA is a layered phosphate (ZPS-IPPA), zirconium poly (styrene-
crystalline mesoporous material and could have potential application phenylvinylphosphonate)-phosphate (ZPS-PVPA) as well as
as a catalyst support for the immobilization of chiral salen Mn(III).
zinc poly (styrene-phenylvinylphosphonate)-phosphate (ZnPS-
PVPA).16–20
Calcium phosphates have long been the focus of extensive
research for their potential use in biological system.21–23 The
range of products in which they can be found includes fertil-
izers, adsorbents for chromate-graphy, and drug delivery
systems. Especially, calcium phosphate crystals, which have
several possible compositions and shapes, are oen used as
materials for environmental purication due to their charac-
teristic feature of high biocompatibility.24 However, less atten-
tion has been paid to calcium phosphonate–phosphate, an
organic–inorganic hybrid material.
In this work, we have explored the possibility of incorpo-
rating copolymer styrene-phenylvinylphosphonic acid into
calcium phosphate (Scheme 1). Synthesis and comparison will
offer deeper insight into the structure and mechanism of
calcium phosphonate–phosphate and help in the design of
more effective catalytic support. With the goal to evaluate the
relevance of the data for the structure-function, the hypothe-
sized model of CaPS-PVPA is proposed and the catalytic
performance of the immobilized chiral salen Mn(III) onto CaPS-
PVPA in the asymmetric epoxidations of non-functionalized
olens is also investigated.
Introduction
Open-framework structures, especially those of metal phos-
phates, have been of great interest in the past few years because
of their potential applications in catalysis and separation
processes, and also due to the fascinating structural features
exhibited by them.1–5 A dramatic increase in structural diversity
accompanies the incorporation of new transition and main
group metals, because of their ability to have coordination
numbers greater than 4, a limitation of aluminosilicate zeolites.
Open-framework metal phosphates have been found to readily
accept the inclusion of various metals.6 In addition, crystalline
metal phosphates (MPs) are used in heterogeneous catalysis,7
molecular sorption,8 and various emerging technologies.9
Amorphous MPs, on the other hand, are employed in automo-
bile engines as antiwear lms,10 in several other optical appli-
cation,11 and in biological implants.12
Our previous works has reported a series of organic–inor-
ganic hybrid zirconium phosphonate–phosphates, such as
zirconium sulfotolyl-phosphonate–phosphate Zr(HPO4)2ꢀx[O3-
PC6H3(CH3)SO3H]x$nH2O, zirconium phosphate–ferric chloride
complex and zirconium (diphenyl-phosphinate-hydrogen
phosphate)–ferric chloride complex Zr(HPO4)1.5[(O2PPh2)$
FeCl2(OH)].13–15 Efforts have been further focused on the
synthesis of zirconium phosphate–phosphonate derivatives as
the supports for the immobilization of chiral salen Mn(III), for
Results and discussion
The sodium content in CaPS-PVPA 3 is 4.6%, which is 0.3%
lower than that of theoretical values. This can be ascribed to the
surface-bound or intercalated water inducing the augmentation
of the molecular weight.
aInstitute for Clean Energy & Advanced Materials, Southwest University, Chongqing,
400715, PR China. E-mail: ecmli@swu.edu.cn
FT-IR spectroscopies of CaPS-PVPA 1–7 are shown in
Fig. S1.† The strong and wide absorption band extending from
3090 cmꢀ1 to 3750 cmꢀ1 by virtue of the –OH veries the pres-
ence of surface-bound or intercalated water. The transmissions
bFaculty of Materials and Energy, Southwest University, Chongqing 400715, PR China
cSchool of Physics and Chemistry, Xihua University, Chengdu, 610039, PR China
† Electronic supplementary information (ESI) available: FT-IR, TG, XRD, N2
adsorption–desorption, SEM, TEM. See DOI: 10.1039/c4ra04299a
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Fig. 1 The hypothesized layered structure of CaPS-PVPA 3.
˚
value but all a set of values around 31 to 32 A. The interlayer
distances of CaPS-PVPA 1–7 are just only one of the represen-
tative interlayer distance values. There are some deviations
among CaPS-PVPA, owing to the introducing of the chains of
styrene-phenylvinylphosphonic acid copolymer. The interlayer
Scheme 1 Synthesis of CaPS-PVPA 1–7.
˚
distances of CaPS-PVPA 1–7 are nearly 32 A broader than that of
˚
Ca3(PO4)2 (3.18 A), which is probably ascribed to the styrene-
around 2900 cmꢀ1 of the samples are ascribed to C–H bond
stretching vibrations of alkyl groups. In the range of 1600–1450
cmꢀ1 and 760–690 cmꢀ1, the absorption bands are owing to the
characteristic absorptions and the exing vibration of phenyl
group, respectively. The other common prominent bands at
1145, 1089, and 986 cmꢀ1 are assigned to R–PO32ꢀ phosphonate
stretching vibrations. The adsorptions at 1201, 1144, and 1077
cmꢀ1 are due to the phosphonate and phosphate stretching
vibrations.
phenylvinylphosphonic acid copolymer chain (Fig. 1) inducing
the calcium layer stretched.
On account of the BET treatment of the isotherms, CaPS-
PVPA 3 indicates low specic surfaces areas (19.35 m2 gꢀ1
)
and pore volume (2.352 ꢂ 10ꢀ2 cm3 gꢀ1) as well as average pore
diameter (4.862 nm). The nitrogen adsorption-desorption
isotherms of CaPS-PVPA 3 (Fig. S4†) are type IV, with a sharp
increase in N2 adsorption at higher P/P0 values (ꢃ0.9) and a
distinct hysteresis loop (type H4), with an almost parallel
adsorption and desorption. With regard to the desorption
isotherm of CaPS-PVPA 3 (Fig. S4†), BJH analysis manifests a
very broad pore size distribution of pore size. The pore diame-
ters of the particles are mainly distributed below 2 nm, and
some vary from 2 nm to 30 nm which is in the scope of meso-
pore. Simultaneously, the size of the solvated Mn(salen)Cl
complex is estimated to be 2.05–1.61 nm by MM2.25 On account
of this, CaPS-PVPA 3 can offer enough room to accommodate
the solvated chiral salen Mn(III) complex. Moreover, the porous
hosted materials do make crucial impact on catalytic perfor-
mance owing to a synergistic effect of the nanoporous solid, the
linker, and chiral salen Mn(III) (Fig. 2).20 The solid support with
hierarchical pore sizes is not only facile to obtain the optimum
pore size for efficient diffusion of reactant and product mole-
cules, but also benecial for the immobilizing of the active
metal complex such as chiral salen Mn(III). Therefore, the local
environment inside the mesopores and pore size of CaPS-PVPA
3 can inuence the enantioselectivity of the epoxidation reac-
tion, which is the crucial performance for catalyst supports to
immobilize chiral salen Mn(III).
TG curves (Fig. S2†) display that CaPS-PVPA 1, 3, 5 lose
ꢁ
surface-bound or intercalated water below 180 C. Aer dehy-
dration, the disintegration of the appended organic fragments
contributes to the apparent weightlessness in the temperature
range of 180–500 ꢁC. And then, calcium phosphonate is
changed into calcium phosphate. Ultimately, there are small
weight losses between 500 and 1000 ꢁC owing to phase changes
from layer to cubic Ca2P2O7 and Ca3(PO4)2. In view of this, the
samples have enough thermal stabilities to be applied as cata-
lyst supports by virtue of organic reactions usually carried out
ꢁ
under 180 C.
Shown in Fig. S3,† XRD patterns of CaPS-PVPA 3 indicate a
lenient 001 peak, accompanying with other peaks at higher-
order 00n peaks such as at 26.42ꢁ and 30.20ꢁ. XRD patterns of
CaPS-PVPA 1–6 display similar patterns as that of Ca3(PO4)2 at
the vicinity of 26.42ꢁ and 30.20ꢁ, due to the sections of inorganic
phosphate in CaPS-PVPA 1–6. XRD patterns of CaPS-PVPA 1–6
close to 19.76ꢁ are proximate to that of CaPS-PVPA 7, owing to
the parts of calcium poly (styrene-phenyl-vinylphosphonate) in
CaPS-PVPA 1–6. Therefore, CaPS-PVPA 1–6 are rather calcium
poly
(styrene-phenylvinylphosphonate)–phosphate
hybrid
SEM images of CaPS-PVPA (Fig. S5†) display that the samples
are composed of irregularly sized layered particles which are
aggregates of many minor crystalline grains. The anomalous
suborbicular segments are congregation of the parts of calcium
inorganic phosphate in CaPS-PVPA; while the inordinate plate
materials than a blend of calcium inorganic phosphate and
calcium poly(styrene-phenylvinylphosphonate). In addition, the
interlayer distances of CaPS-PVPA 1–7 which could be calcu-
lated (via the Bragg equation, nl ¼ 2d sin q), are not a single
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Table 2 The recycles of catalysta in the asymmetric epoxidation of a-
methylstyreneb
Run
Time (h)
Con. (%)
eec (%)
TOFd ꢂ 10ꢀ4 (Sꢀ1
)
1
2
3
4
5
6
7
8
5
5
5
5
5
5
5
5
5
5
5
5
>99
>99
>99
>99
98
97.5
95
93
90
88
83
76
>99
>99
>99
>99
>99
>99
97
95
87
80
72
11.11
11.11
11.11
11.11
11.00
10.94
10.66
10.44
10.1
9
10
11
12
9.88
9.31
8.53
Fig. 2 The hypothesized structure of the heterogeneous catalyst.
36
a
The catalyst was the immobilized chiral salen Mn(III) catalysts on
b
p-phenylenedi-amine modied CaPS-PVPA. Reactions were carried out
layers are congregation of proportions of calcium poly(styrene- at ꢀ40 ꢁC in CH2Cl2 (2 mL) with a-methylstyrene (1 mmol), n-nonane
(internal standard, 1 mmol), m-CPBA (0.38 mmol), heterogeneous salen
phenylvinyl-phosphonate) in CaPS-PVPA. Simultaneously,
generous caves, holes, pores and channels also exist in every
Mn(III) catalysts (5 mol%). The conversion and the ee value were
determined by GC with chiral capillary columns HP19091G-B213,
particle. Moreover, some micropores and secondary channels 30 m ꢂ 0.32 mm ꢂ 0.25 mm. c Same as in Table 1. d Same as in Table 1.
can increase the surface area of the catalyst and further induce
substrates accessing to the catalytic active sites readily.
TEM micrographs of CaPS-PVPA 3 (Fig. S6†) indicate that the
areatus sections in a wide variety of sizes are attributed to
accumulation of parts of calcium inorganic phosphate in CaPS-
PVPA and the zonary segments with different width are ascribed
to congregation of proportion of calcium poly(styrene-
phenylvinylphosphonate) in CaPS-PVPA. Meanwhile, various
shapes of channels, holes and cavums can also be discerned
clearly. Therefore, substrates can approach the internal catalytic
active sites in solution more easily.
of a-methylstyrene and indene. The conversions and ee values
of the epoxide are determined by GC. The primary results are
summaried in Table 1. The performance of catalyst C is
signicant higher than that of catalyst D and E prepared by our
group before. Further researches are in progress.
The homogeneous catalyst E indicates higher ee value than
that of the Jacobsen's catalyst (ee, 90.8–54%), which manifests
that the rigid linker is devoted to the increase of ee values.
Moreover, the ee values further increases from 90.8% to >99%
aer the homogeneous catalyst E is immobilized onto CaPS-
PVPA (C). In a word, the whole immobilized chiral salen
Mn(III) catalysts include the support CaPS-PVPA, the rigid
linkers and chiral salen Mn altogether contribute to the
increase of ee values.
The activity of the catalyst with immobilization of chiral
salen Mn(III) onto CaPS-PVPA is investigated for the epoxidation
Table
1 Asymmetric epoxidation of a-methylstyrene and indene
Obviously, the yield and the enantioselectivity decrease
slightly aer recycling for nine times and still give conversion
(90%) and enantioselectivity (87%) (Table 2). The effective
separation of the chiral Mn(III) salen complexes by the solid
catalyzed by heterogeneous catalysts with m-CPBA/NMOa as oxida-
tive system
Con
TOFd
ee (%) 10ꢀ4 (sꢀ1
ꢂ
Entry Substrateb Catalystc Time (%)
)
1
2
3
4
5
6
A
A
A
B
B
B
C
D
E
C
D
E
6
6
6
6
6
6
>99
56
64
>99
62
98.7
>99
18
90.8
>99
59
83.7
9.26
5.24
5.99
9.26
5.80
9.23
Table
3 Large-scale asymmetric epoxidation reaction of a-
methylstyrenea
Entry
Time (h)
Con. (%)
eed (%)
TOFe ꢂ 10ꢀ4 (Sꢀ1
)
1b
2c
5
5
>99
>99
>99
>99
11.11
11.11
a
Reactions were carried out at ꢀ20 ꢁC in CH2Cl2 (4 mL) with a-methyl-
styrene (1 mmol) or indene (1 mmol), n-nonane (internal standard, 1
mmol), NMO (5 mmol), homogeneous (5 mol%) or heterogeneous
salen Mn(III) catalysts (5 mol%) and m-CPBA (2 mmol). The n-nonane, m-CPBA, heterogeneous salen Mn(III) catalysts (5 mol%). The
a
Reactions were carried out at ꢀ40 ꢁC in CH2Cl2 with a-methylstyrene,
conversion and the ee value were determined by GC with chiral conversion and the ee value were determined by GC with chiral capillary
b
b
capillary columns HP19091GB213, 30 m ꢂ 0.32 mm ꢂ 0.25 mm. A ¼ columns HP19091G-B213, 30 m ꢂ 0.32 mm ꢂ 0.25 mm. The usage
c
a-methylstyrene, B ¼ indene. C ¼ the immobilized chiral salen amounts of reagents were a-methylstyrene (50 mmol), n-nonane (50
Mn(III) catalysts on p-phenylenedi-amine modied CaPS-PVPA. D ¼ mmol), heterogeneous catalyst (0.5 mmol), m-CPBA (100 mmol),
c
the immobilized chiral salen Mn(III) catalysts on p-phenylenediamine respectively. The usage amounts of reagents were a-methylstyrene
modied ZPS-IPPA.19 E ¼ the homogenous chiral salen Mn(III) catalyst (100 mmol), n-nonane (100 mmol), heterogeneous catalyst (5 mmol),
d
d
e
modied by p-phenylenediamine.25 TOF ¼ [product]/[catalyst] ꢂ m-CPBA (200 mmol), respectively. Same as in Table 1. Same as in
time (sꢀ1).
Table 1.
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support CaPS-PVPA contribute to the superior stability of the
heterogeneous chiral Mn(III) salen catalyst in the case that they
would dimerize to form the inactive m-oxo-Mn(IV) species. The
decrease of the yield could be ascribed to the decomposition of
the chiral Mn(III) salen complex under epoxidation conditions,
and the loss of the hyperne granules of the heterogeneous
chiral Mn(III) salen catalysts.
Shown in Table 3, the conversion and enantioselectivity
maintain at the same level for the large-scale reactions under
whichever condition that the large scale is 50 times or 100 times
as much as the experimental scale.
2 T. W. Stephen, M. L. Brent, A. M. Celeste, R. C. Thomas and
M. F. Edith, J. Am. Chem. Soc., 1982, 104, 1146.
3 T. W. Stephen, et al., ACS Symp. Ser., 1983, 218, 79.
4 W. O. Haag, Stud. Surf. Sci. Catal., 1994, 84, 1375.
5 I. Z. Stacey and E. D. Mark, Curr. Opin. Solid State Mater.
Chem., 1996, 1, 107.
6 J. N. Alexander and O. H. Dermot, J. Am. Chem. Soc., 2004,
126, 6673.
7 G. Nathalie, et al., Angew. Chem., Int. Ed., 2001, 40, 2831.
8 M. F. Paul, et al., J. Am. Chem. Soc., 2003, 125, 1309.
9 E. D. Mark, Nature, 2002, 417, 813.
10 A. N. Mark, D. Than, R. N. Peter, K. G. Masoud and
B. Michael, Tribol. Int., 2005, 38, 15.
11 J. H. Campbell and T. I. Suratwala, J. Non-Cryst. Solids, 2000,
263–264, 318.
12 I. Ahmed, C. A. Collins, M. P. Lewis, I. Olsen and
J. C. Knowles, Biomaterials, 2004, 25, 3223.
13 B. K. Luo, X. K. Fu and Q. Y. Lei, Ion Exch. Adsorpt., 1995, 11,
162.
14 B. K. Luo, X. K. Fu and Q. Y. Lei, Ion Exch. Adsorpt., 1993, 9,
124.
Conclusions
In conclusion, a novel layered crystalline organic copolymer–
inorganic hybrid material CaPS-PVPA has been synthesized and
characterized. We are exploring calcium phosphate/
phosphonate/phosphinate systems to draw a more universal
understanding of the formation of phosphate-based frame-
works. The results suggest that the relative reactivities of
calcium and styrene-phenylvinylphosphonic acid copolymer are
crucial in the formation of a special structure. Moreover, CaPS-
PVPA could be employed as a superior support for the immo-
bilization of chiral salen Mn(III), allowing catalyst disposition in
the use of asymmetric epoxidation of unfunctionalized olens.
15 X. K. Fu, W. Kang, S. Y. Wen and C. Y. Deng, Chin. J. Appl.
Chem., 1995, 12, 47.
16 W. S. Ren, X. K. Fu, H. B. Bao, R. F. Bai, P. P. Ding and
B. L. Sui, Catal. Commun., 2009, 10, 788.
17 X. B. Tu, X. K. Fu, X. Y. Hu and Y. D. Li, Inorg. Chem.
Commun., 2010, 3, 404.
18 B. W. Gong, X. K. Fu, J. X. Chen, Y. D. Li, X. C. Zou, X. B. Tu,
P. P. Ding and L. P. Ma, J. Catal., 2009, 262, 9.
19 J. Huang, X. K. Fu, G. Wang, C. Li and X. Y. Hu, Dalton Trans.,
2011, 40, 3631.
Acknowledgements
This work was nancially supported by the Fundamental
Research Funds for the Central Universities (XDJK2013C120)
and the Xihua University Key Projects (Z1223321) and Sichuan
Province Applied Basic Research Projects (2013JY0090) and the
Department of Education of Sichuan Province Projects
(13ZB0030), and also the nancial support from Faculty of
Materials and Energy, Southwest University, China and
Chongqing Special Funding for Postdoctoral (Xm2014028) and
Chongqing Postdoctoral Daily Fund (Rc201419).
20 J. Huang, X. K. Fu, G. Wang and Q. Miao, Dalton Trans., 2012,
41, 10661.
21 R. Z. LeGeros, Clin. Orthop. Relat. Res, 2002, 395, 81.
22 D. Bruce, S. Charles, R. W. Shelly, H. John and H. Jeffrey,
Crit. Rev. Eukaryotic Gene Expression, 2001, 11, 173.
23 C. P. A. T. Klein, A. A. Driessen, K. D. Groot and
A. V. D. Hooff, J. Biomed. Mater. Res, 1983, 17, 769.
24 N. Motoko, et al., J. Home Econ. Jpn., 2007, 58, 203.
25 J. Huang, X. K. Fu and Q. Miao, Catal. Sci. Technol., 2011, 1,
1472.
References
1 L. C. R. Jesse, R. M. Andrew, S. P. Kyo and M. Y. Omar, J. Am.
Chem. Soc., 2004, 126, 5666.
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