Synthesis, crystal structure, and luminescent properties of a novel cadmium coordination polymer

Article abstract of DOI:10.1080/15533174.2012.680113

A novel cadmium metal-organic coordination polymer, namely Cd(atda)(3-abpt)(H₂O)·2H₂O (H₂ atda = (4-amino-1,2,4-triazole- 3,5-diyldithio) diacetic acid, 3-abpt = 4-amino-3,5-bis(3-pyridyl)- 1,2,4-triazole)), has been obtai

Full text of DOI:10.1080/15533174.2012.680113

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Synthesis, Crystal Structure, and Luminescent
Properties of a Novel Cadmium Coordination Polymer
Yong He a , Wen-Juan Chu a , Lu-Meng Duan a , Yao-Ting Fan a & Hong-Wei Hou a
a Department of Chemistry , Zhengzhou University , Zhengzhou , Henan , P. R. China
Accepted author version posted online: 06 Jul 2012.Published online: 01 Oct 2012.
To cite this article: Yong He , Wen-Juan Chu , Lu-Meng Duan , Yao-Ting Fan & Hong-Wei Hou (2012) Synthesis, Crystal
Structure, and Luminescent Properties of a Novel Cadmium Coordination Polymer, Synthesis and Reactivity in Inorganic, Metal-
Organic, and Nano-Metal Chemistry, 42:9, 1246-1250, DOI: 10.1080/15533174.2012.680113
To link to this article: http://dx.doi.org/10.1080/15533174.2012.680113
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 42:1246–1250, 2012
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2012.680113
Synthesis, Crystal Structure, and Luminescent Properties
of a Novel Cadmium Coordination Polymer
Yong He, Wen-Juan Chu, Lu-Meng Duan, Yao-Ting Fan,
and Hong-Wei Hou
Department of Chemistry, Zhengzhou University, Zhengzhou, Henan, P. R. China
Our recent efforts were focused on the design of metal-
organic coordination frameworks with distinctive topologies
by using flexible carboxylate ligands containing N-donor lig-
ands such as triazole. Herein we report a novel neutral MOFs
with 2-D supramolecular framework built from flexible ligands
(4-amino-1,2,4-triazole-3,5-diyldithio) diacetic acid (H2atda),
furthermore, a rarely reported line linker ligand 4-amino-3,5-
bis(3-pyridyl)-1,2,4-triazole (3-abpt) was also introduced to the
system. The complex was characterized by single-crystal X-
ray diffraction analysis, elemental analysis, and IR. Besides,
the fluorescence spectra in solid state were measured at room
temperature.
A novel cadmium metal-organic coordination polymer, namely
Cd(atda)(3-abpt)(H2O)·2H2O (H2atda = (4-amino-1,2,4-triazole-
3,5-diyldithio) diacetic acid, 3-abpt = 4-amino-3,5-bis(3-pyridyl)-
1,2,4-triazole)), has been obtained under hydrothermal conditions
by the reaction of cadmium salts with two kinds of organic ligands,
characterized by single-crystal X-ray diffraction analysis, elemen-
tal analysis, and thermogravimetric analysis. Structural analysis
reveals that complex possesses a 2D honeycomb network. Addition-
ally, the complex show strong fluorescence in solid state at room
temperature.
Keywords complex, honeycomb network, luminescence property
EXPERIMENTAL
INTRODUCTION
Materials and Measurements
Design and self-assembly of metal-organic frameworks
(MOFs) with desirable topological networks have received con-
siderable attention in the field of solid-state materials.[1–3] Re-
cent years numerous coordination polymers constructed by
rigid bridging ligands such as aromatic polycarboxylates or
diamines[4,5] with attractive properties such as gas adsorp-
tion,[6–8] electronic,[9] nonlinear optical,[10] and magnetism[11]
were reported. In contrast, flexible carboxylate-containing lig-
ands, which can adopt various conformations, may induce co-
ordination polymers with novel topologies and luminescent
properties have not been extensively studied.[12–14] In addi-
tion, the coordination preferences between metal centers and
the auxiliary ligand also have an enormous impact on the
framework structure; the introduction of rod-like neutral N,Nꢁ-
donor building block, such as the well-known 4,4ꢁ-bipyridine,
into MOFs may induce spatial effect to produce unexpected
architectures.[17–19]
All chemicals were of reagent grade quality and obtained
from commercial sources, and used without further purification.
H2atda were prepared according to the literature procedure.[20]
Elemental analysis (C, H, N) were performed on a Carlo-Erba
1160 elemental analyzer (Italy). IR spectra were recorded in
the region of 4000–400 cm−1 on a FTS-40 infrared spectropho-
tometer (Bio-Rad Laboratories, Inc., USA) with pressed KBr
pellets. Thermogravimetry was carried out with a NETZSCH
STA 409 unit (Germany) at a heating rate of 10◦C/min under
air atmosphere. Emission spectra were recorded on an F-4500
HITACHI florescence spectrophotometer (Japan).
Synthesis of 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole
(3-abpt)
4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole was synthesized
according to the reported procedures in the literature and was
slightly modified.[21] The mixture of nicotinic acid (25 mL),
NH2NH2·H2O (80%, 3 ml) were sealed and heated in a 15 mL
Teflon-lined autoclave at 180◦C for 3 days, then followed by
slow cooling (5◦C·h−1) to room temperature. The colorless nee-
dle crystals were obtained and collected by filtration. All solid
products were collected and dried at air atmosphere. The yield
of 3-abpt was ca. 73%. Anal. Calcd. (%) for C12H10N6: C,
60.50; H, 4.23; N, 35.29. Found (%): C, 60.52; H, 4.21; N,
35.26. IR (KBr, cm−1): 3752(w), 3431(s), 3324(vs), 3182(s),
2378(w), 2287(w), 1638(m), 1573(s), 1514(w), 1460(s),
Received 12 April 2011; accepted 28 December 2011.
The authors gratefully acknowledge the financial support from the
National Natural Science Foundation of China (Nos. 20871106 and
90610001).
Address correspondence to Yao-Ting Fan, Department of Chem-
istry, Zhengzhou University, Zhengzhou 450052, Henan, P. R. China.
E-mail: yt.fan@zzu.edu.cn
1246

A NOVEL CADMIUM COORDINATION POLYMER
1247
TABLE 1
Synthesis of [Cd(atda)(3-abpt)(H2O)]·2H2O (1)
Crystallographic data and relevant data referring to the
structure solution and refinement
Complex 1 was hydrothermally synthesized by the reactions
of Cd(NO3)2·4H2O (0.5 mmol, 154.25 mg), H2atda (0.5 mmol,
132 mg), NaOH (1 mmol, 40 mg), 3-abpt (0.5 mmol, 119 mg),
and deionized water (14 mL) in a sealed Teflon-lined stainless
steel vessel (25 mL) at 130◦C for 7 days. After being slowly
cooled to room temperature, crystals of 1 (colorless, prism-like)
were collected by filtration. Yield: 48% based on Cd. Anal.
Calcd. (%) for C18H16CdN10O7S2: C, 35.45; H, 3.54; N, 20.68.
Found (%): C, 35.57; H, 3.34; N, 20.81. IR data (KBr, cm−1):
3553(m), 3527(m), 3380(m), 1630(s), 1594(vs), 1575(vs),
1482(w), 1411(s), 1382(s),1237(s), 1113(m),1035(w), 900(m),
773(m), 693(s).
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
C18H16CdN10O7S2
660.93
293(2)
0.71073
Monoclinic
P2(1)/n
Unit cell dimensions (Å, ◦)
a
b
c
9.6278(19)
21.175(4)
12.237(2)
α
90.00
β
94.92(3)
γ
90.00
2485.5(8), 4
1320
Crystallographic Data Collection and Structure
Determination
Volume (Å3), Z
F(000)
Single crystal of 1 was put on a Bruker SMART APEX
II CCD diffractometer (Germany) equipped with graphite-
monochromatic Mo-Kα radiation (λ = 0.71073 Å) by using
the omega scan mode at 293(2) K. Data integration and reduc-
tion were performed using APEX suitsoftware (Bruker AXS
Inc., Germany). The structure was solved by direct method and
refined by full-matrix least-squares on F2 with anisotropic dis-
placement using the SHELXS-97 program (Sheldrick, G. M.,
University of Go¨ttingen, Germany).[22] All non-hydrogen atoms
of the metal and the ligands were refined with anisotropic dis-
placement paremeters. Therefinement converged at R1 = 0.0500
and wR2 = 0.1365 values for reflection with I > 2σ for the title
compound. Details of crystal structure determination are sum-
marized in the Table 1. Full atomic data are available as a file in
CIF format. The selected bond lengths and angles are shown in
Table 2.
Calculated density (g cm−3
Goodness-of-fit on F2
Data/restraints/parameters
Final R indices [I > 2σ(I)]
R indices (all data)
θ range (◦)
)
1.766
1.130
7391/0/343
R1 = 0.0500, wR2 = 0.1365
R1 = 0.0570, wR2 = 0.1423
1.92–31.21
0.81 and −0.59
Largest difference peak and hole
(e Å−3
)
ꢀ
ꢀ
ꢀ
ꢀ
2
2 2
R1 =
w(F0 ) ]
ꢂ F0 \ − \ Fc ꢂ/ \ F0 \; wR2 = [ w(F0 − Fc ) /
2 2 1/2
1421(s), 1394(w), 1359(w), 1333(w), 1275(w), 1191(w),
1133(m), 1046(w), 1026(m), 1007(w), 967(s), 920(s), 816(s),
714(vs), 624(m).
TABLE 2
Selected bond lengths (Å) and angles (◦) for complex 1
Cd(1)-O(1)
Cd(1)-O(3)
Cd(1)-O(4)
2.263 (3)
2.290 (2)
2.324 (3)
139.84 (12)
85.14 (12)
134.78 (9)
100.14 (14)
87.94 (10)
87.49 (11)
92.51 (14)
82.56 (10)
126.7 (2)
115.3 (2)
98.8 (2)
Cd(1)-O(5)
Cd(1)-N(9)
Cd(1)-N(10)
2.612 (3)
2.360 (3)
2.352 (3)
93.28 (11)
167.35 (10)
137.52 (11)
82.11 (8)
52.68 (8)
84.48 (9)
85.96 (9)
115.0 (2)
85.44 (19)
127.0 (3)
103.3 (3)
O(1)-Cd(1)-O(3)
O(1)-C(d1)-O(4)
O(3)-Cd(1)-O(4)
O(1)-Cd(1)-N(10)
O(3)-Cd(1)-N(10)
O(4)-Cd(1)-N(10)
O(1)-Cd(1)-N(9)
O(3)-Cd(1)-N(9)
C1(7)-N(10)-Cd(1)
C(11)-N(9)-Cd(1)
C(6)-O(4)-Cd(1)
O(4)-Cd(1)-N(9)
N(10)-Cd(1)-N(9)
O(1)-Cd(1)-O(5)
O(3)-Cd(1)-O(5)
O(4) Cd(1) O(5)
N(10)-Cd(1)-O(5)
N(9)-Cd(1)-O(5)
C1(8)-N(10)-Cd(1)
C(6)-O(5)-Cd(1)
C(7)-N(9)-Cd(1)
C(1)-O(1)-Cd(1)
Symmetry transformations used to generate equivalent atoms: #1 x – 1/2, –y + 1/2, z + 1/2; #2 –x + 1, –y, –z + 1; #3 x + 1/2, –y + 1/2, z –
1/2.

1248
Y. HE ET AL.
bis(carboxymethylmercapto)-1,3,4-thiadiazole acid) in which
the deprotonated ligand takes bidentate chelating/bidentate
bridging mode to coordinate with cadmium centers lead to
2D rectangular grids.[25] However, in complex 1, the carboxyl
groups of atda2− ligand adopt monodentate chelating mode
at one end and bidentate chelating mode at the other to link
cadmium centers into a 1D infinite zigzag chain (Figure 2).
Furthermore, these 1D infinite chains are further linked into 2D
honeycomb layers owing to the connectivity of 3-abpt ligand
(Figure 3). It is noted that there are two kind of separation
between cadmium ions, the intrachain Cd . . . Cd separations
are 8.327 Å, whereas the interchain separations are 8.742 Å.
Noticeably, if we regard each cadmium atoms as a connecting
node, the framework of 1 can be described as a (6,3) honeycomb
topology, as shown in Figure 4.
FIG. 1. The coordination environment of Cd1 (uncoordinated water molecules
and hydrogen atoms are omitted for clarity) (color figure available online).
These 2D layers and lattice water molecules are involved
into strong hydrogen bonding and these hydrogen bonds play
an important role in the constructing and stabilizing the 3D
supramolecular framework.
RESULTS AND DISCUSSION
Crystal Structure Description
Crystallographic analysis reveals that complex 1 crystallizes
in the monoclinic system, space group P2(1)/n, and the
asymmetric unit consists of one Cd atom, one atda2− ligand,
one 3-abpt ligand, one coordination water, and two lattice
water. As shown in Figure 1, each Cd(II) is six coordinated and
sits in a distorted octahedron environment, which contains two
Spectra Properties and TG Analyses
The IR spectra of complex display the characteristic ab-
nitrogen atoms (N9, N10) from two different 3-abpt ligands and sorptions of the ligand anions. The band in the range of
five oxygen atoms from two different atda2− anions (O1, O4, 1710–1740 cm−1, which assigned to the stretching bands of
O5) and one water molecule (O3). The Cd-O distances range –COOH, was disappeared indicating the deprotonation of the
from 2.263 Å to 2.612 Å, which is within the extent expected carboxyl groups.
for such species.[23] Each ligand coordinated with two Cd2+,and
The strong bands for complex appear at 1594, 1575, 1411,
the coordinate mode that the carboxyl groups of atda2− adopted and 1382 cm−1, which are assigned to the asymmetric and sym-
is different form those reported before. Recently, our group metric stretching bands of COO− groups, respectively, suggest-
has reported a complex [Cd(L)(4,4-bipy)]·2H2O (H2L = 1,2- ing that the COO− groups function in different coordination
bis[3-(1,2,4-triazolyl)-4-amino-5-carboxylmethylthio]ethane),
modes. In addition, the strong broad bands for 1 in the region
in this complex the two carboxyl group of the ligand adopt of 3500–3300 cm−1 are attributed to -NH2 group stretching and
chelating-bridging and bidentate chelating mode linking bending vibration. The results of IR spectrum of 1 match up
Cd2+ resulting a 2D layer in the ac plane.[24] Xue et al. to that of X-ray crystal structure analysis and charge balance
reported a complex [Cd(bct)(H2O)(4,4ꢁ-bipy)0.5] (H2bct = 2,5- considerations.
FIG. 2. The 1-D zigzag chain in complex 1 (uncoordinated water molecules, 3-abpt ligand, and hydrogen atoms are omitted for clarity) (color figure available
online).

A NOVEL CADMIUM COORDINATION POLYMER
1249
FIG. 3. The 2-D layer linked by 3-abpt ligands (uncoordinated water molecular and hydrogen atoms are omitted for clarity) (color figure available online).
To examine the luminescent properties of the complex, the starts at about 100◦C and ends at 265◦C, implying the removal
luminescence spectra of complex, H2atda as well as the 3-abpt of one coordinated and two lattice water molecules, and then
have been measured at room temperature. As depicted in Fig- the second step of rapid weight loss between 265◦C and 625◦C,
ure 5, the H2atda exhibited the intense luminescence emission corresponding to the decomposition of the organic moieties. The
bands at about 403 nm upon excitation at 340 nm while the last step of weight loss starts from 625◦C to 705◦C and owes
3-abpt ligand shows an emission band at about 380 nm. In to the further decomposition of organic moieties. The resulting
comparison to that of the free ligand, the emission peaks of residue was not characterized.
complex at 398 nm was much similar to that of H2atda and was
slightly blue shifted, and the enhancement and slightly shift of
SUPPLEMENTARY MATERIALS
the emission bands may be attributed to the intraligand π→ π∗
Crystallographic data for the structural analyses have been
transitions from the atda2− ligand whose chelating effect can
effectively increase the rigidity of ligand.
deposited to the Cambridge Crystallographic Data Center,
Thermogravimetric analysis to measure the thermal stability
of frameworks were carried out by heating complex to 800◦C at
10◦C/min under air and TGA curve are shown in Figure 6. As
it is revealed there are three main steps of weight losses. The
first step is weight loss of about 8.7% (calculated 8.2%), which
FIG. 4. Backbone showing the (6,3) network (a) and the honeycomb topology FIG. 5. The solid-state emission spectra of H2atba, 3-apbt and complex 1
of 1 (b) (color figure available online).
(color figure available online).

1250
Y. HE ET AL.
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FIG. 6. The TG curve of complex 1.
CCDC Nos. 819056. Copies of this information may be ob-
tained free of charge from The Director, CCDC, 12 Union
Road, Cambridge, CB2 1EZ, UK (Fax: +44-1223-336033;
E-mail: deposit@ccdc.cam.ac.uk, or http://www.ccdc.cam.ac.
uk.).
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