A new heterometallic coordination polymer: Synthesis, structure, and catalytic property

Article abstract of DOI:10.1080/15533174.2016.1158188

A new heterometallic-organic framework, namely [CuCa(tdc)₂(DMF)]_n(1 H₂tdc = 2,5-thiophenedicarboxylic acid, DMF = N,N’-dimethylformamide), has been successfully obtained through the solvothermal reactions of CuCl₂, Ca(NO₃)₂, and H₂tdc. Single-crystal structural analysis reveals that compound 1 features a 3D framework with the irl topology. Compound 1 has potential unsaturated metal sites after the removal of the coordinated DMF molecules, so it exhibits excellent catalytic activity for the diethylzinc addition to benzaldehyde.

Full text of DOI:10.1080/15533174.2016.1158188

Inorganic and Nano-Metal Chemistry
ISSN: 2470-1556 (Print) 2470-1564 (Online) Journal homepage: http://www.tandfonline.com/loi/lsrt21
A new heterometallic coordination polymer:
Synthesis, structure, and catalytic property
Qi-Feng Liu, Wei Liu, Yi-Po Cao, Yan-Li Dong & Hui-Min Liu
To cite this article: Qi-Feng Liu, Wei Liu, Yi-Po Cao, Yan-Li Dong & Hui-Min Liu (2017) A new
heterometallic coordination polymer: Synthesis, structure, and catalytic property, Inorganic
and Nano-Metal Chemistry, 47:1, 153-157, DOI: 10.1080/15533174.2016.1158188
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Date: 11 November 2016, At: 04:49

INORGANIC AND NANO-METAL CHEMISTRY
2017, VOL. 47, NO. 1, 153–157
http://dx.doi.org/10.1080/15533174.2016.1158188
A new heterometallic coordination polymer: Synthesis, structure, and
catalytic property
Qi-Feng Liua, Wei Liub, Yi-Po Caoc, Yan-Li Donga, and Hui-Min Liua
aCollege of Sciences, Agricultural University of Hebei, Baoding, P. R. China; bDepartment of Basic Medcine, logistics University of CAPF, Tianjin,
P. R. China; cTianjin Provincal Corps Hospital of Chinese People’s Armed Police Force, Tianjin, P. R. China
ABSTRACT
ARTICLE HISTORY
Received 28 December 2015
Accepted 21 February 2016
A new heterometallic-organic framework, namely [CuCa(tdc)2(DMF)]n (1 H2tdc D 2,5-thiophenedicarboxylic
acid, DMF D N,N’-dimethylformamide), has been successfully obtained through the solvothermal reactions
of CuCl2, Ca(NO3)2, and H2tdc. Single-crystal structural analysis reveals that compound 1 features a 3D
framework with the irl topology. Compound 1 has potential unsaturated metal sites after the removal of
the coordinated DMF molecules, so it exhibits excellent catalytic activity for the diethylzinc addition to
benzaldehyde.
KEYWORDS
Catalytic property;
heterometallic compound;
solvothermal reaction;
topology
Introduction
Oxford Xcalibur E diffractometer with ꢀgraphite-monochro-
mated Mo-Ka radiation (λ D 0.71073 A). Elemental analy-
ses (C, H, and N) were performed on an EA1110 CHNS-0
CE Elemental Analyzer. Powder X-ray diffraction (PXRD)
analyses were recorded on a Rigaku Dmaꢀx2500 diffractome-
ter with Cu-Ka radiation (λ D 1.54056 A) with a step size
of 0.05ꢀ. Thermogravimetric analyses were carried out on a
NetzschSTA499C integration thermal analyzer under a
nitrogen atmosphere from 30 to 800ꢀC at a heating rate of
10ꢀC/min.
Metal-organic frameworks (MOFs) have attracted much attention
of scientists, owing to not only their impressive structural diversity
but also their potential applications as functional materials in the
fields of luminescence, gas storage/separation, magnetism, and
heterogeneous catalysis.[1–5] Because the well-known HKUST-1
and MIL-101 have been successfully applied to catalyze the cyano-
silylation of benzaldehyde,[6,7] MOF-based catalysis has become a
research hotspot in recent years. According to previously reported
documents, MOFs materials as catalysts must have accessible
active metal centers in the structures.[8,9] Therefore, how to con-
struct MOFs with appropriate active metal centers is extremely
important. An effective method is to construct inorganic building
blocks with terminal coordinated solvent molecules, the removal
of which will generate coordinatively unsaturated metal sites.
Although a lot of MOFs have been successfully applied to catalyze
organic reactions, most of them are mainly single metal–based
MOFs.[10–12] Comparatively speaking, heterometallic-organic
frameworks as heterogeneous catalysts are rarely reported.[13,14]
Based on these considerations, we successfully constructed a new
heterometallic-organic framework, namely [CuCa(tdc)2(DMF)2]n
(1 H2tdc D 2,5-thiophenedicarboxylic acid, DMF D N,N’-
dimethylformamide). In this work, we will report the synthesis,
structure, and catalytic property of this compound.
Synthesis of [CuCa(tdc)2(DMF)2]n
A mixture of CuCl2ꢁ2H2O (0.018 g, 0.1 mmol), Ca
(NO3)2ꢁ4H2O (0.024 g, 0.1 mmol), H2tdc (0.034 g,
0.2 mmol), DMF (2 mL), and CH3OH (2 mL) was placed
in a 20 mL small vial. Then the mixture was heated to
70ꢀC. The temperature was held for 60 h, then the vessel
was cooled to room temperature over 30 min, leading to
the formation of green crystals of 1 (yield: 35% based on
H2tdc). Anal. Calcd. for 1, C18H16N2O10S2CuCa: C, 36.73;
H, 2.72; N, 4.76%. Found: C, 36.73; H, 2.74, N, 4.73%. IR
(cm¡1): 3421(w), 1715(m), 1678(s), 1584(m), 1479(m), 1382
(m), 1373(m), 1109(w), 1021(w), 957(m), 892(m), 815(m),
778(w), 690(w).
Experimental
X-ray crystallography
Materials and methods
The X-ray single crystal structure analysis of 1 was per-
All chemicals were purchased commercially and used with- formed on an Oxford Xcalibur E diffractometer (Mo-Ka
ꢀ
out further purification. X-ray intensities were collected on radiation, λ D 0.71073 A, graphite monochromator) at 293
CONTACT Hui-Min Liu
huimin_liu3157@126.com
College of Sciences, Agricultural University of Hebei, Baoding 071001, P. R. China.
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/lsrt.
CCDC No. 991738 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via
www.ccdc.cam.ac.uk/data_request/cif, by emailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12, Union Road,
Cambridge CB2 1EZ, UK. Fax:C44 1223336033.
© 2017 Taylor & Francis Group, LLC

154
Q.-F. LIU ET AL.
Table 1. Crystallographic data for compound 1.
Result and discussion
Empirical formula
Temperature (K)
Crystal color
Crystal size
Formula weight
Crystal system
C18H16N2O10S2CaCu
293(2)
Description of the structure
green
Single crystal X-ray structural analysis reveals that compound 1
crystallizes in triclinic P ¡1 space group with the asymmetric
unit containing one Cu(II) ion, two Ca(II) ions with the occu-
pancy of 0.5, two tdc2– ligands, and two coordinated DMF mol-
ecules. As shown in Figure 1, Cu1 is coordinated by four
carboxylate oxygen atoms from four different tdc2– ligands, dis-
playing a quadrilateral geometric configuration. Ca1 and Ca2
are six-coordinated with octahedral coordination geometries,
which are defined by four carboxylate oxygen atoms from four
different tdc2– ligands and two oxygen atoms of coordinated
DMF molecules. The Cu-O and Ca-O distances are in the range
0.18£ 0.16£ 0.14 mm3
588.10
triclinic
Space group
P¡1
ꢀ
a (A)
10.3660(6)
ꢀ
b (ꢀA)
c (A)
a (ꢀ)
b (ꢀ)
10.4724(6)
12.9582(5)
95.243(4)
102.189(4)
106.434(5)
1301.57(12)
g (ꢀ)
ꢀ
Volume (A3)
Z
2
Density (calcd.)
Abs. coeff. (mm¡1
F(000)
1.501 g/cm3
)
1.247
598
ꢀ
ꢀ
of 1.932(2)–2.001(2) A and 2.282(2)–2.367(2) A, respectively.
In 1, tdc2– ligand links four metal ions (two Ca(II) ions and
two Cu(II) ions) with its two carboxylate groups in uniform
bis-monodentate mode. The Cu(II) ions and Ca(II) ions are
alternately linked by the carboxylate groups into a infinite chain
subunit (Figure 2a). Each infinite chain is further connected to
four adjacent infinite chains by tdc2– ligands, resulting in the
formation of the 3D framework (Figure 2c). To better under-
stand this complicated framework of 1, topological analysis
based on nomenclature of rod packing was used to simplify
Refinement method
Reflections collections
Independent reflections
u range for data collection
h,k,l range
Full-matrix least-squares on F2
10564
5876 (Rint D 0.0262)
2.41–29.14
¡32 ꢀ h ꢀ 18, ¡8 ꢀ k ꢀ 13, ¡17 ꢀ l ꢀ 17
1.032
Goodness-of-fit on F2
Final R indices [I>2sigma(I2)]
R (all data)
R D 0.0453, wR2 D 0.1196
R D 0.0591, wR2 D 0.1297
ꢀ
Largest difference peak and hole 0.906 and ¡0.647 A3
(2) K. Empirical absorption corrections were applied to the this framework. The carboxylate C atoms are at the vertices of
data using the SADABS program.[15] The structure was each infinite chain, and the connectivity between these C atoms
solved by the direct method and refined by the full-matrix results in a 1D zigzag ladder-like chain (Figure 2a). If the tdc2–
least squares on F2 using the SHELXL-97 program.[16] All ligands can be reduced into rod-shaped linkers (Figure 2b),
of the non-hydrogen atoms were refined anisotropically, these zigzag ladder-like chains are further linked together by
and the hydrogen atoms attached to carbon were located at the rod-shaped linker, giving rise to a 3D network with irl
their ideal positions. Experimental details for the structure topology (Figure 2d). As we known, heterometallic frameworks
determination are presented in Table 1. Selected bond with irl topology are rarely reported.
lengths and angles are listed in Table 2.
Catalytic property
ꢀ
Table 2. Selected bond lengths (A) and angles (ꢀ) of compound 1.
In compound 1, each Ca(II) ion has two coordinated DMF
molecules, and the coordinated DMF molecules can be
removed out by the means of heating. The desolvated samples
Cu(1)-O(3)a
1.932(2)
1.953(2)
2.282(2)
2.301(2)
2.367(3)
2.308(2)
2.315(2)
2.323(3)
Cu(1)-O(8)b
1.946(2)
2.001(2)
2.282(2)
2.301(2)
2.367(3)
2.308(2)
2.315(2)
2.323(3)
Cu(1)-O(1)
Cu(1)-O(5)
Ca(1)-O(7)b
Ca(1)-O(7)c
Ca(1)-O(2)
Ca(1)-O(2)d
Ca(1)-O(10)d
Ca(1)-O(10)
Ca(2)-O(4)e
Ca(2)-O(4)a
Ca(2)-O(6)
Ca(2)-O(9)
Ca(2)-O(6)f
Ca(2)-O(9)f
O(3)a-Cu(1)-O(8)b
O(8)b-Cu(1)-O(1)
O(8)b-Cu(1)-O(5)
O(7)b-Ca(1)-O(7)c
O(7)c-Ca(1)-O(2)
O(7)c-Ca(1)-O(2)d
O(7)b-Ca(1)-O(10)d
O(2)-Ca(1)-O(10)d
O(7)b-Ca(1)-O(10)
O(2)-Ca(1)-O(10)
O(10)d-Ca(1)-O(10)
O(4)e-Ca(2)-O(6)
O(4)e-Ca(2)-O(6)f
O(6)-Ca(2)-O(6)f
O(4)a-Ca(2)-O(9)
O(6)f-Ca(2)-O(9)
O(4)a-Ca(2)-O(9)f
O(6)f-Ca(2)-O(9)f
90.48(10)
92.68(11)
169.39(10)
180.000(1)
93.01(9)
O(3)a-Cu(1)-O(1)
O(3)a-Cu(1)-O(5)
O(1)-Cu(1)-O(5)
O(7)b-Ca(1)-O(2)
O(7)b-Ca(1)-O(2)d
O(2)-Ca(1)-O(2)d
O(7)c-Ca(1)-O(10)d
O(2)d-Ca(1)-O(10)d
O(7)c-Ca(1)-O(10)
O(2)d-Ca(1)-O(10)
O(4)e-Ca(2)-O(4)a
O(4)a-Ca(2)-O(6)
O(4)a-Ca(2)-O(6)f
O(4)e-Ca(2)-O(9)
O(6)-Ca(2)-O(9)
O(4)e-Ca(2)-O(9)f
O(6)-Ca(2)-O(9)f
O(9)-Ca(2)-O(9)f
165.00(10)
92.28(11)
87.29(11)
86.99(9)
93.01(9)
86.99(9)
180.00(11)
84.93(12)
91.65(11)
95.07(12)
88.35(11)
180.00(14)
87.81(8)
95.07(12)
88.35(11)
84.93(12)
91.65(11)
180.00(13)
92.19(8)
87.81(8)
92.19(8)
180.00(14)
88.97(12)
90.27(10)
91.03(12)
89.73(10)
91.03(12)
89.73(10)
88.97(12)
90.27(10)
180.00(15)
Figure 1. View of the coordination environments of Cu(II) and Ca(II) ions in 1. Sym-
metry codes: (a) 2 – x, 1 – y, 1 – z; (b) x, 1 C y, z; (c) 2 – x, – y, 1 – z; (d) 1 – x, –y, –z;
(e) ¡1 C x, y, z.
Symmetry codes: (a) x – 1, y, z; (b) x, y C 1, z; (c) –x C 2, –y, –z C 1; (d) –x C 2, –y
C 1, –z C 1; (e) –x C 2, –y, –z; (f) –x C 1, –y, –z.

INORGANIC AND NANO-METAL CHEMISTRY
155
Figure 2. (a) 1D heterometallic chain subunit (left) and a zigzag ladder deduced from the connectivity between carboxylate C atoms. (b) Representation of tdc2– ligand as
linker. (c) The 3D framework of 1. (d) Schematic representation of irl topological network for 1.
have coordinately unsaturated metal sites, so it can act as Lewis 10 min. Third, the hexane (2 mL) solvent was added via syringe
acid catalyst. To evaluate the catalytic activity of the desolvated under nitrogen and the mixture was stirred for 30 min. Fourth,
sample of 1, the reaction of diethylzinc addition to benzalde- benzaldehyde (0.25 mL) and diethylzinc (in n-hexane, 1 mL)
hyde was used (Figure 3a). First, compound 1 was dried under were added, and the new mixture was stirred under nitrogen at
vacuum at 250ꢀC for 2 h, affording the activated samples suit- 25ꢀC. In order to detect the yield of the phenylpropanol, a small
able for the catalytic reaction. Second, the activated samples amount of solution was taken out in a certain time interval and
were placed in a 25 mL Schlenk flask and then vacuumized for quenched with saturated NH4Cl solution and ethyl acetate. The
composition of the reaction mixture was characterized by the
gas chromatograph (GC) analysis (Figure 4). From the GC, we
can observe the phenylpropanol in the products. At the time of
30 h, the concentration of phenylpropanol reached 47.8%. After
30 h, the concentration of phenylpropanol has no obvious
change (Figure 3b). In addition, we have also done several
Figure 3. (a) The addition reactions of diethylzinc with benzaldehyde. (b) The con-
centration of phenylpropanol with time for 1.
Figure 4. The view of the gas chromatograph spectrum for compound 1 as the
catalyst.

156
Q.-F. LIU ET AL.
Figure 5. The view of the gas chromatograph spectrum. (a) Metal salts alone. (b) Free organic ligand. (c) Metal salts and free organic ligand.
Figure 6. (a) Powder X-ray diffraction patterns for 1 (a, simulated powder patterns; b, sample powder patterns; c, thermal tread sample patterns [250ꢀC for 2 h]; d, after
catalytic experiment). (b) TG curve of 1.
parallel experiments by using the metal salts, organic ligand as (calcd. 24.49%) in the temperature range of 150–234ꢀC corre-
well as the mixture of organic ligand and metal salts under the sponds to the release of the coordinated DMF molecules. Then,
similar reaction conditions, the results suggest that they show the desolvated samples can be stable up to 310ꢀC. After 310ꢀC,
no catalytic effect for this reaction (Figure 5).
a sharp weight loss may be assigned to the decomposition of
the organic ligand.
PXRD patterns and thermal analysis
Conclusions
The phase purity of compound 1 was confirmed by the powder
X-ray diffraction. The experimental pattern of the bulk samples
of 1 is in good agreement with the simulated one based on the
single-crystal diffraction data. The peak of powder X-ray pat-
tern for the activated sample moved a little to the lower angle,
indicating that the desolvated sample may have a little change.
The powder X-ray pattern of the activated sample after catalysis
is consistent with that of the activated samples (Figure 6). Ther-
mal analysis for 1 was also performed on polycrystalline sam-
ples under N2 atmosphere in the temperature range of 30–
In summary, we have successfully obtained a new 3D hetero-
metallic-organic framework with irl topology, which has poten-
tial unsaturated sites after the removal of the coordinated DMF
molecules. It shows good catalytic activity for the diethylzinc
addition to benzaldehyde.
Funding
This work was supported by grants from the Sci-technical Support Project
800ꢀC. As shown in Figure 6b, the weight loss of about 24.32% of Hebei Province (14227115D).

INORGANIC AND NANO-METAL CHEMISTRY
157
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