Synthesis, structure, and catalytic performance of heterobimetallic coordination polymers with β-diketone containing imidazole group

Article abstract of DOI:10.1016/j.poly.2018.10.050

Four heterobimetallic coordination polymers [Cd[Al(L)₃]₂(NO₃)₂ (1), Zn[Al(L)₃]₂(NO₃)₂ (2), Zn[Fe(L)₃]₂(NO₃)₂ (3), and [ZnFe

Full text of DOI:10.1016/j.poly.2018.10.050

Accepted Manuscript
Synthesis, Structure, and Catalytic Performance of Heterobimetallic Coordina-
tion Polymers with β-diketone containing imidazole group
Yan Huang, Ping Yang
PII:
S0277-5387(18)30686-7
https://doi.org/10.1016/j.poly.2018.10.050
POLY 13524
DOI:
Reference:
Polyhedron
To appear in:
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Revised Date:
Accepted Date:
5 August 2018
9 October 2018
17 October 2018
Please cite this article as: Y. Huang, P. Yang, Synthesis, Structure, and Catalytic Performance of Heterobimetallic
Coordination Polymers with β-diketone containing imidazole group, Polyhedron (2018), doi: https://doi.org/
10.1016/j.poly.2018.10.050
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Graphical abstract
Complex [ZnFe(L)3Cl](NO3)·3(MeOH)·3(DMF) can catalyze the ring opening of
epoxides with aromatic amines to produce β-amino alcohols at room temperature.
1

Abstract
Four
heterobimetallic
coordination
polymers
[Cd[Al(L)3]2(NO3)2
(3),
(1),
Zn[Al(L)3]2(NO3)2
(2),
Zn[Fe(L)3]2(NO3)2
and
[ZnFe(L)3Cl](NO3)·3(MeOH)·3(DMF) (4) have been synthesized. The structural
analyses of coordination polymers 1-4 showed that they were trigonal space group,
among which, coordination polymer 4 was P3 chiral space group. The circular
dichroism spectra also confirmed that coordination polymer 4 had chirality. Zn(II) ion
in coordination polymer 4 was tetracoordinated, unsaturated, can act as Lewis acid
catalyst. Therefore, coordination polymer 4 can catalyze the ring opening of epoxides
with aromatic amines to produce β-amino alcohols at room temperature. The catalytic
reaction was regioselective, easy to operate, and had good catalyst recovery and
repeatability.
Keywords: Catalysis; Heterometallic coordination polymer; β-diketone; imidazole
2

Synthesis, Structure, and Catalytic Performance of Heterobimetallic
Coordination Polymers with β-diketone containing imidazole group
Yan Huang a, Ping Yang b, *
a Department of Xinsha, Guangzhou entry exit inspection and Quarantine Bureau,
Guangzhou 510623, China;
b School of Environment, Jinan University, Guangzhou 511443, China
1. Introduction
Increasing the functionalization of heterometallic coordination polymers has attracted
the attention of many researchers. The most studied heterometallic coordination
polymers are 3d-4f heterometallic coordination polymers, which are often used in
magnetic applications [1, 2] and transition metal complexes for sensitizing rare earth
luminescence [3, 4]. The latter can red shift the excitation wavelength to the visible
region and can also be used as white light material when the emission is
complementary [5, 6]. The p-d and d-d heterometallic coordination polymers have
similar coordination properties, which make it difficult to build coordination
compounds, and thus, they need careful selection of corresponding strategies [7]. In
general, some ligands with atoms that have different coordination ability can be
selected, and a small molecular complex is first formed. Then, the uncoordinated
atom is further coordinated and assembled with another metal ion to obtain a desired
heterometallic coordination polymer. For example, pyridine 2,4-dicarboxylic acid [8,
*
Corresponding author: Ping Yang, School of Environment, Jinan University, Guangzhou, 511443,
China. E-mail: 191723030@qq.com
3

9] and pyrazine 2-carboxylic acid [10-14] can be coordinated with different metal ions
to form heterometallic coordination polymers.
N-containing β-diketone ligands are also a good class of ligands for building
heterometallic coordination polymers. For example, 1-(4-pyridyl)-1,3-butanedione
(4-PBD) can be coordinated with tetrahedral Be to form a polyline metalloligand, and
it can then be further assembled into a one-dimensional chain with tetrahedral Cd [15].
The sketch of the ligand is shown in Scheme 1. 4-PBD can also generate tripodal
metalloligand with six-coordinated Al, and then it can be assembled with tetrahedral
Zn to form trigonal bipyramidal cages or assembled with quadrilateral Pd to form
cap-octahedral cages [16]. 1,3-Bis(4-pyridyl)-1,3-propanedione (4-BPPD) can
generate a six exo-oriented donor metalloligand with hexacoordinated Fe. A
two-dimensional layer can be formed when four donors participate in coordination via
tetrahedral coordination of Ag. A binodal 5,4-connected 2-fold interpenetrated
three-dimensional network is formed when five donors are coordinated, and a trinodal
6,3,4-connected three-dimensional network is formed when six donors are
coordinated [17]. 3-(4-Pyridyl)-2,4-pentanedione (4-PPD) reacts with tetracoordinate
Be/Cu to form a linear metalloligand, forming a planar triangular metalloligand with
Fe/Al, and then it reacts with N-philic Co, Cu, Ag, Zn, Cd, and Hg to form a one- or
two-dimensional structure [15, 18-22].
In recent years the application of coordination polymers has shifted to catalysis
because the coordinately unsaturated metal sites can act as Lewis acid catalysts for
nucleophilic substitution reactions, such as ring opening of epoxide with amine [23,
4

24]. β-Amino alcohols, which are synthesized through aminolysis of epoxides with
corresponding amines, have a wide range of applications in medicine, non-natural
amino acids, and chiral auxiliary asymmetric synthesis [25-28]. High reaction
temperatures and excess nucleophiles are often required in the absence of a catalyst,
and these result in lower yields, poor reaction regioselectivity, and stereoselectivity
[29, 30]. To solve these problems, a wide variety of catalysts have been developed
[31-33]. Coordination polymers has high crystallinity and uniform pores to make they
can catalyze reactions with selectivity based on substrate size and shape. Moreover,
the catalytic active sites of coordination polymers can be tuned via their metal nodes
or organic ligands through pre-synthetic or post-synthetic approaches. In view of the
advantages of coordination polymer catalysts, therefore, it is necessary to expand
more research.
In the structural regulation synthesis of our previous studies [34, 35], it was found that
1-(4-(1H-imidazol-yl)phenyl)butane-1,3-dione (HL) preferred a trans-configuration
and that the coordination angle was larger, which facilitated building high
dimensional structures. Moreover, HL contains N and O coordination atoms and can
be coordinated with metal ions that have different properties, and thus, it has the
potential to be used in constructing heterobimetallic coordination polymers. In this
paper, the ligand was chosen to react with O-philic Fe/Al ions and N-philic Zn/Cd
ions to generate the heterobimetallic coordination polymers and the catalytic activity
of these compounds toward ring opening reactions of epoxides with aromatic amines
was studied.
5

Scheme 1 Sketches of the ligands 4-PBD, 4-BPPD, 4-PPD and HL.
2. Experimental Section
2.1 Materials and Methods
All chemicals used were analytical reagent and were not pretreated before use.
Elemental analysis (C, H, N) was measured using a Elementar Vario EL elemental
analyzer. IR spectra was performed on a Bruker TENSOR 27 (4000-400 cm–1)
infrared spectrometer using KBr pellets. NMR spectra were recorded on a Varian
Mercury-Plus 300 MHz NMR spectrometer, and all chemical shifts were based on
TMS as a reference. Electron spray ionization mass spectrometry (ESI-MS) was
recorded on a SHIMADZU LCMS-2010A mass spectrometer to obtain the molecular
ion peak of compound, and methanol was selected as the carrier solvent. Thermal
analysis was carried out on Netzsch TG 209 F3 Tarsus thermogravimetric analyzer
6

(nitrogen atmosphere). The reference compound was Al2O3, and the heating rate was
10 °C/min. The powder X-ray diffraction (PXRD) was measured on a Bruker D8
advanced diffractometer with Cu Kα radiation (λ = 0.15409 nm) at a scanning rate of
4°/min with 2θ ranging from 5 to 35°. PXRD patterns simulated with a single crystal
data were generated using the software Mercury 1.4.2. Circular dichroism (CD)
spectra were collected on a JASCO J-810 CD spectrometer. UV-Vis spectra were
recorded on a CARY-300 spectrometer (VARIAN). GC-MS studies were performed
with a Shimadzu instrument (QP 2010) with an RTX-5SIL-MS column. The ligand
1-(4-(1H-imidazol-yl)phenyl)butane-1,3-dione (HL) was synthesized according to our
previous articles [34, 35].
2.2 Synthesis of coordination polymer 1
H2O/EtOH (2 mL, 1/1) was carefully layered on a solution of Al(NO3)3·9H2O (0.02
mmol) and Cd(NO3)2·2H2O (0.03 mmol) in water (1 mL), and then a solution of HL
(0.06 mmol) in ethanol (1 mL) was further layered on the buffer solution. After
standing for a week, colorless crystals of Cd[Al(L)3]2(NO3)2 (1) were obtained (11 mg,
yield 65% based on Al). C78H66N14O18Al2Cd: calcd. C 56.65; H 4.02; N 11.86%;
found: C 56.04; H 4.10; N 11.73%. IR (KBr pellet, cm−1): 3432 w, 3119 w, 1605 m,
1561 m, 1537 m, 1510 s, 1452 m, 1405 m, 1383 s, 1305 m, 1259 w, 1190 w, 1122 w,
1059 w, 1016 w, 962 w, 854 m, 780 w, 655 w, 620 w, 472 w.
2.3 Synthesis of coordination polymer 2
The precursor Al(L)3 was readily prepared according to mix Al(NO3)3·9H2O and HL
in H2O/EtOH (1/1). Then, DMF (1 mL) was carefully layered on a solution of Al(L)3
7

(0.03 mmol) in dichloromethane (2 mL), and then a solution of Zn(NO3)2·6H2O (0.09
mmol) in methanol (1 mL) was further layered on the buffer solution. After standing
for a week, colorless crystals of Zn[Al(L)3]2(NO3)2 (2) were obtained (8 mg, yield 33%
based on Al). C78H66N14O18Al2Zn: calcd. C 58.31; H 4.14; N 12.20%; found: C 57.90;
H 4.31; N 11.97%. IR (KBr pellet, cm−1): 3430 w, 3115 w, 1601 m, 1563 m, 1535 m,
1509 s, 1453 m, 1404 m, 1386 s, 1304 m, 1269 w, 1189 w, 1130 w, 1058 w, 1014 w,
962 w, 854 m, 780 w, 656 w, 620 w, 475 w.
2.4 Synthesis of coordination polymer 3
A solution of HL (0.1 mmol) in DMF (2 mL) was added to a solution of
Fe(ClO4)2·6H2O (0.03 mmol) in methanol (1 mL) and shaken well. Then, a solution
of Zn(NO3)2·6H2O (0.05 mmol) in methanol (1 mL) was added. After standing for a
week, red crystals of Zn[Fe(L)3]2(NO3)2 (3) were obtained (11 mg, yield 43% based
on Fe). C78H66N14O18Fe2Zn: calcd. C 56.28; H 4.00; N 11.78%; found: C 55.93; H
4.16; N 11.56%. IR (KBr pellet, cm−1): 3427 w, 3115 w, 1601 m, 1563 m, 1535 m,
1509 s, 1448 m, 1403 m, 1384 s, 1310 m, 1253 w, 1189 w, 1122 w, 1059 w, 1016 w,
962 w, 851 m, 781 w, 660 w, 627 w, 471 w.
2.5 Synthesis of coordination polymer 4
A solution of HL (0.1 mmol) in DMF (2 mL) was added to a solution of FeCl3·6H2O
(0.03 mmol) in methanol (1 mL) and shaken well. Then, a solution of Zn(NO3)2·6H2O
(0.05 mmol) in methanol (1 mL) was added. After standing for a week, red crystals of
[ZnFe(L)3Cl](NO3)·3(MeOH)·3(DMF) (4) were obtained (24 mg, yield 65% based on
Fe). Elemental analysis for (C51H66N10O15ZnClFe): Anal. Calcd. C, 51.70; H, 5.58; N,
8

11.83; found: C, 51.74; H, 5.55; N, 11.81. IR (KBr pellet, cm−1): 3439 w, 3114 w,
1672 cm, 1602 m, 1561 m, 1532 m, 1516 s, 1456 m, 1403 m, 1387 s, 1303 m, 1254 w,
1198 w, 1126 w, 1058 w, 1013 w, 968 w, 857 m, 780 w, 658 w.
To confirm the effect of the Cl ion on the structure, A solution of HL (0.1 mmol) in
DMF (2 mL) was added to a solution of Al(NO3)3·9H2O (0.03 mmol) in methanol (1
mL) and shaken well. Then, a solution of ZnCl2 (0.05 mmol) in methanol (1 mL) was
added. After standing for a week, colorless crystals were obtained (cell parameters
were similar to those of 4).
2.6 Catalytic test
Generally, the central metal of coordination polymers with coordinatively unsaturated
sites has the possibility to have the catalytic activity [23, 36]. However, the central
metal of coordination polymers 1-3 are all saturated with hexacoordinates, so
coordination polymers 1-3 were not tested in catalysis. An equimolar mixture of
epoxides (5 mmol, epichlorohydrin, 1,2-epoxyethylbenzene, and cyclohexene oxide)
and aniline (5 mmol) was stirred at room temperature and solvent-free conditions in
the presence of 0.5% catalyst (coordination polymer 4). The reaction was monitored
using a TLC method. After reaction 6 h, 2 mL of ethyl acetate was added to dilute the
solution, and the solid catalyst was removed via filtering. The crude product was
purified by column chromatography on silica gel using hexane / ethyl acetate mixture
(5:1) as the eluent. The products were identified and quantified by ESI-MS, NMR,
and GC-MS techniques. The recovered catalyst was washed with diethyl ether, dried,
and reused without further purification or regeneration. The control group was treated
9

with no catalyst.
2.7 X-ray crystallography
Data for the coordination polymers of 1-4 were collected on a Bruker Smart Apex
CCD area detector and a Rigaku R-AXIS SPIDER IP (Mo Kα, λ = 0.071073 nm or
Cu Kα, λ = 0.154178 nm), and the SADABS program were used for absorption
correction. The crystal structure was obtained using the direct method and refined
using the SHELXTL package on a full-matrix least-squares structure based on F2.
Except for the extremely severely disordered atoms, other non-hydrogen atoms were
refined anisotropically. The geometric hydrogenation method was used to add
hydrogen atoms on the organic group, and the differential Fourier synthesis method
was employed to add hydrogen atoms to the solvent water. Parts of Solvents and
counter anions cannot be refined because of weak diffraction, and SQUEEZE was
used for the overall quality of the data. Further details of the X-ray structural analyses
for coordination polymers 1-4 are given in Table 1 and Table 2. The selected bond
lengths for 1-4 are listed in Table A.1.
3. Results and discussion
3.1 Crystal structure
As seen in Table 1, coordination polymers 1-3 were trigonal space group (R−3 or
R−3c) and had similar structures (see Supporting Information). The structure of
coordination polymer 1 is taken as an example for discussion. The independent unit
contained one Al(III) ion, one Cd(II) ion, and one HL ligand molecule. Solvents and
10

counter anions cannot be refined because of weak diffraction, and SQUEEZE was
used for the overall quality of the data [37]. The Al(III) ion was on the three-fold
rotational axis and was chelated by six oxygen atoms of the β-diketone group of three
ligands (Fig. 1), and the three imidazole groups pointed to the same end, forming a
tripodal metalloligand (Fig. 2a). The Cd(II) ion was on a six-fold rotational axis,
surrounded by six imidazole N atoms of six ligands, and can be seen as six junctions.
Each ligand was trans-bridged with one Al(III) ion and one Cd(II) ion, which can be
seen as connecting lines and simplified the structure to a two dimensional kgd
topology (Fig. 2b).
Fig. 1 ORTEP drawing of coordination polymer 1 with thermal ellipsoids 30%
probability. This is a partial view of the compound. Symmetry code: A 1–y, x–y, z. B
1–x+y, 1–x, z. C y, –x+y, –z. D –x+y, –x, z. E x–y, x, –z. F –x, –y, –z. G –y, x–y, z.
The kgd topology can be considered as a stack of Cd3Al4(L)9 unit by edge sharing.
Each Cd3Al4(L)9 unit can be considered as a parallelepiped lacking a vertex (Fig. 2a),
with included angles of 73.5° and 106.5° and a side length of 12.55 Å. The layers can
11

attract each other through weak C(1)–H(1)•••O(2) hydrogen bonds (3.527(5) Å,
106.4(3)°) to form ABC••• type stacks (Fig. 2c and Fig. 2d). A regular quadrilateral
channel (12.55 × 12.55 Å) was formed in the layer with a void ratio of 50.6%.
Compared to 4-PBD, the metalloligand formed by HL with the first metal (Al/Fe)
were also three-pronged, and the angles were similar (71.45°~86.46°). However, since
the second metal was an octahedral six-junction rather than a V-shaped two-junction
or planar four-junction, and thus, the structure dimension increased [16].
Fig. 2 (a) schematic drawing, (b) kgd topology, (c) hydrogen bonds, and (d) stacking
diagram of coordination polymer 1.
12

As seen in Table 2, coordination polymer 4 was a trigonal system and P3 chiral space
group. The independent contained one Fe(III) ion, one Zn(II) ion, one HL ligand
molecule, one methanol molecule, one DMF molecule, and two counter anions. The
Fe(III) ions on the three-fold rotational axis were coordinated by six oxygens of the
β-diketone group of three ligands (Fig. 3). The Fe(III) ions was a chiral center. The
three imidazole groups pointed to the same end, forming a tripodal metalloligand
(angle 82.4°). Due to the different size and geometry of anions in the reaction, the
coordination sphere of zinc ion and network structures of coordination polymer 4 are
different from those of coordination polymer 1 [38-40]. The Zn(II) ion on the
three-fold rotational axis was surrounded by three imidazole N atoms of three ligands
and one chloride ion and can be seen as three junctions. Each ligand bridged one
Fe(III) ion and one Zn(II) ion in trans bridges, and this can be seen as connecting lines
and simplified the structure to a two dimensional hcb topology (Fig. 4a).
Fig. 3 ORTEP drawing of coordination polymer 4 with thermal ellipsoids 30%
probability. Symmetry code: A: 1 – y, x – y, z. B: 1 –x + y, 1 – x, z. C: –y, x – y, z. D:
–x + y, –x, z.
13

Compared to coordination polymer 1, each Fe3Zn3(L)6 unit is equivalent to a
parallelepiped that removes two vertices from the body diagonal, and can be regarded
as a chair hexagon (Fig. 4a) with an included angle of 82.4° and a side length of 12.3
Å. The units were connected in a wave layer via a shared edge, and the layers
overlapped and shaded into each other through weak C(9)–H(9)···Cl(1) hydrogen
bonds (3.70(1) Å, 150.4(8)°) (Fig. 4b). A hexagonal channel with a diameter of about
8 Å was formed in the c direction with a void rate of 44.8%.
Fig. 4 (a) hcb topology and (b) hydrogen bonds and stacking diagram of coordination
polymer 4.
14

3.2 Powder X-ray Diffraction
As seen in Fig. A.1 and Fig. A.2, the powder X-ray diffraction pattern of coordination
polymer 1 and 4 agreed well with the powder X-ray diffraction pattern simulated from
the single crystal data, indicating that the products were a pure phase (see Supporting
Information).
3.3 Solid state Circular Dichroism spectra of coordination polymer 4
As seen in Fig. 5, coordination polymer 4 had a broad UV absorption peak at 340 nm
(ε = 1.15×105 L·mol−1·cm−1), 4-R (with right-hand configuration) had a positive CD
absorption peak at 353 nm, and the CD spectrum of 4-L (with left-hand configuration)
mirrored each other.
Fig. 5 UV-Vis spectra of coordination polymer 4, ethanol solution with a
concentration of 1×10−5 mol/L; the CD spectra of coordination polymer 4 in the solid
state at room temperature.
15

3.4 Ring opening of epoxides catalyzed by coordination polymer 4
As seen in Scheme 2, the tetracoordinated Zn(II) in coordination polymer 4 was
surrounded by three imidazole groups and one chloride ion. The zinc ion is sp3
hybridization and unsaturated (the saturation state is sp3d2), and their empty 4d orbital
could accept electron pairs. So coordination polymer 4 can be regarded as a Lewis
acid catalyst, which accepts nucleophilic attack of the O atom in the epoxides, thus
catalyzing amination [23].
Scheme 2 Possible mechanism of coordination polymer 4 for catalytic ring opening of
epoxides with aromatic amine.
Because the lone pair of electrons in the arylamine participated in the aromatic ring
π-conjugation and reduced its nucleophilicity, the reaction rate of the epoxides with
aniline at room temperature was very low. In this context, a catalyst is often required
to activate the epoxides to promote reaction. Coordination polymer 4 was employed
to catalyze the reaction of aniline and cyclohexene oxide, 1,2-epoxyethylbenzene, and
epichlorohydrin to investigate its catalytic performance. Under these conditions, a
smooth reaction resulted that produced the corresponding β-amino alcohol in high
yield (Table 3).
16

When coordination polymer 4 was used to catalyze the reaction of cyclohexene oxide
with aniline, product 1 (2-(phenylamino)cyclohexan-1-ol) was obtained as a single
1
product. Mass spectrometry: m/z = 192 (M+1). H NMR (CDCl3, 300 MHz): δ 1.18
(m, 1H); 1.34 (m, 3H); 1.76 (m, 2H); 2.11 (m, 2H); 3.16 (m, 1H); 3.43 (m, 1H); 6.85
1
(m, 3H); 7.21 (t, 2H). The mass spectrum and H NMR spectrum are shown in Fig.
A.3. It was also found that higher yields (94%) can be obtained in the absence of
solvent at room temperature.
For comparison, the author also used coordination polymer 4 to catalyze the reaction
of
1,2-epoxyethylbenzene
with
aniline
to
give
product
2
(1-phenyl-2-(phenylamino)ethan-1-ol) as a single product. Mass spectrometry: m/z =
214 (M+1). 1H NMR (DMSO-d6, 300 MHz): δ 3.59 (m, 2H); 4.32 (d, 1H); 4.95 (t, 1H,
OH); 5.94 (d, 1H, NH); 6.47 (m, 3H); 6.95 (t, 2H); 7.17 (t, 1H); 7.27 (t, 2H); 7.34 (d,
1
2H). The mass spectrum and H NMR spectrum are shown in Fig. A.4. The aniline
attacked the carbon without the phenyl substituent, which has low activity, instead of
the common the carbon with the phenyl substituent [28]. It was also found that higher
regioselective products can be obtained at room temperature under solvent-free
conditions; yield: 88%.
When catalyzing the reaction of epichlorohydrin with aniline, the aniline may attack
either the carbon with the chloromethyl substituent or the carbon without the
1
chloromethyl substituent or both, although the mass spectrometry and H NMR
spectra of product 3 showed a pure compound (Fig. A.5). Mass spectrometry: m/z =
1
186 (M+1). H NMR (DMSO-d6, 300 MHz): δ 3.05 (m, 1H, –CH2–); 3.15 (m, 1H, –
17

CH2–); 3.61 (m, 1H, –CH2–); 3.67 (m, 1H, –CH2–); 3.83 (s, 1H, >CH–); 5.31 (s, 1H,
OH); 5.52 (s, 1H, NH); 6.51 (t, 1H, benzene, J = 15 Hz, J’ = 6 Hz, J’’ = 9 Hz); 6.59 (d,
2H, benzene, J = 9 Hz); 7.04 (t, 2H, benzene, J = 15 Hz, J’ = 9 Hz, J’’ = 6 Hz). To
13
determine which C reacted, the author recorded C nuclear magnetic spectroscopy of
product 3 (Fig. A.6). 13C NMR (DMSO-d6, 300 MHz): δ 47.52, 48.82, 69.57, 112.79,
116.47, 129.52, 149.24. The results show that only the carbon without the
chloromethyl
substituent
was
attacked
(product
3
is
1-chloro-3-(phenylamino)propan-2-ol), indicating that coordination polymer 4 has
regioselective catalysis. In addition, the TLC study found a small amount of a second
product,
which
was
characterized
as
product
4
(3,3'-(phenylazanediyl)bis(1-chloropropan-2-ol)) after purification via column
chromatography (Fig. A.7). Mass spectrometry: m/z = 278 (M + 1). 1H NMR (CDCl3,
300 MHz): δ 3.24 (dd, 1H); 3.47 (dd, 1H); 3.62 (m, 5H); 3.88 (d, 1H); 4.16 (m, 2H);
6.70-6.86 (m, 3H); 7.23-7.29 (m, 2H). These results show that coordination polymer 4
can catalyze the ring opening of epoxides by primary amines and also catalyze
secondary amines. To obtain product 3 as a single product, a slight excess of aniline is
sufficient. This indicates that coordination polymer 4 has good regioselective catalysis
for aromatic amine nucleophilic attack on the ring-opening reaction of alkylene oxide,
and thus, it can be used as a standby catalyst for this reaction.
4. Conclusion
In summary, we used the ligand HL to culture four heterobimetallic coordination
18

polymers that were classified in two categories via the slow evaporation and liquid
phase diffusion at room temperature. Coordination polymers 1-3 were
two-dimensional kgd layers. As expected, the oxygen-binding Fe/Al ions in these
coordination polymers coordinated with the β-diketones of the three ligands, and the
nitrogen-philic Zn/Cd ions coordinated with the imidazoles of the six ligands. The
Fe(III) ions in coordination polymer 4 still had three chelated β-diketones, but the
Zn(II) ions became four-coordinate because of the introduction of chloride ions in
FeCl3 in the raw material, and this resulted in a two-dimensional hcb layer structure.
Thus, the anion had a certain effect on the structure configuration. Coordination
polymers 1-4 each had a large void content and can each be used as a potential
adsorbent storage material. The Zn(II) ion coordination in coordination polymer 4 was
unsaturated and had Lewis acidity. Coordination polymers 4 can catalyze the ring
opening of epoxides with aromatic amines to produce β-amino alcohols at room
temperature. The catalytic reaction was regioselective, easy to operate, and had good
catalyst recovery and repeatability.
Appendix A. Supplementary data
CCDC < 801392, 1849432, 1849442, 1849461, and 1849462 > contains the
supplementary crystallographic data for < Coordination polymers 1-4 >. These data
can
be
obtained
free
of
charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from
the
Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44)
1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
19

Supplementary
data
to
this
article
can
be
found
online
at
https://doi.org/10.1016/j.poly.xxxx.xx.xxx.
Acknowledgements
This work was supported by the National Natural Science Foundation of China [grant
number 41701349] and Sun Yat-Sen University.
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22

Table 1 Crystal data and structure refinement for coordination polymers 1-3
1
2
3
Coordination polymer
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
C78H66N12O12Al2Cd
1529.79
153(2)
C78H66N12O12Al2Zn
1482.76
153(2)
C78H66N12O12Fe2Zn
1540.50
153(2)
0.71073
Rhombohedral
R–3
0.71073
Rhombohedral
R–3
0.71073
Rhombohedral
R–3c
a (Å)
15.0191(8)
15.0191(8)
45.789(3)
8945.0(9)
3
16.1469(9)
16.1469(9)
43.317(5)
9780.6(14)
3
13.3219(7)
13.3219(7)
89.148(8)
13701.7(16)
6
b (Å)
c (Å)
3
V (Å )
Z
3
0.852
0.755
1.120
Dc (Mg/m )
-1
0.242
0.242
0.631
μ (mm )
F(000)
2364
2310
4776
Reflections collected
Unique, Rint
9195
11504
11773
3823, 0.0653
3823 / 0 / 160
1.082
4204, 0.0978
4204 / 18 / 173
1.036
3005, 0.0523
3005 / 0 / 160
0.994
Data/restraints/parameters
2
GOF on F
R1 [I>2σ(I)]
0.0754
0.1010
0.0425
wR2 (all data)
0.2329
0.3027
0.1062
Δρmax / Δρmin (e·Å–3)
0.573 / –0.875
0.587 / –0.381
0.406 / –0.387
23

Table 2 Crystal data and structure refinement for coordination polymer 4
4-R
4-L (SQUEEZE)
C39H33N6O6ZnClFe
838.38
Coordination polymer
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
C51H66N10O15ZnClFe
1183.75
153(2)
153(2)
1.54178
Trigonal
P3
0.71073
Trigonal
P3
a (Å)
16.1741(3)
16.1741(3)
6.4604(2)
1463.63(6)
1
16.173(3)
16.173(3)
6.497(3)
1471.7(8)
1
b (Å)
c (Å)
3
V (Å )
Z
3
1.411
0.946
Dc (Mg/m )
-1
3.539
0.735
μ (mm )
F(000)
649
430
Reflections collected
Unique, Rint
5185
4334
3136, 0.0289
3136 / 7 / 243
1.088
1901, 0.0421
1901 / 1 / 164
0.995
Data/restraints/parameters
2
GOF on F
R1 [I>2σ(I)]
0.0859
0.0890
wR2 (all data)
0.2674
0.2398
Flack parameter
Δρmax / Δρmin (e·Å–3)
0.087(15)
1.897 / –2.616
0.08(5)
1.443 / –1.779
24

Table 3 Ring opening reactions of a few epoxides with aniline using catalyst
coordination polymer 4
Entrya Epoxide
Product
Yield
(%)b
94,
93c,
92d
1
2
88
3
75
b
aConditions: catalyst 0.5%; 6 h stirring, room temperature. Yield calculated from the
GC-MS using internal standard. c,dIsolated yield after third and fifth run, respectively.
As a control, reactions without any catalyst under identical conditions gave negligible
products (yield < 5%).
25