A polymeric cobalt compound [Co(DCNT)(H2O)]n with novel topology: Synthesis, structure, luminescence, and magnetic property

Article abstract of DOI:10.1016/j.inoche.2007.04.023

The hydrothermal reaction of Co(NO₃)₂ · 6H₂O and a new designed ligand H₂DCNT yields a three-dimensional polymer [Co(DCNT)(H₂O)]_n (1), H₂DCNT = 2,4-bis(4-carboxyphenylamino)-6-diethylamino-1,3,5-triazine. In the structure of 1, each DCNT^2- has three coordination sites, one nitrogen atom in the triazine ring coordinating to Co(II) and two carboxylates adopting μ₂-bridging mode, which make the infinite Co(II) chains array uniformly and evenly toward crystallographic c-axis. Luminescent and magnetic properties of 1 were also studied.

Full text of DOI:10.1016/j.inoche.2007.04.023

Inorganic Chemistry Communications 10 (2007) 910–913
www.elsevier.com/locate/inoche
A polymeric cobalt compound [Co(DCNT)(H2O)]n with novel
topology: Synthesis, structure, luminescence, and magnetic property
a
a,
b
a
a
Yongqin Wei , Kechen Wu *, Ria Broer , Botao Zhuang , Yunfang Yu
a
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fujian 350002, China
b
Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
Received 24 January 2007; accepted 12 April 2007
Available online 27 April 2007
Abstract
The hydrothermal reaction of Co(NO3)2 Æ 6H2O and a new designed ligand H2DCNT yields a three-dimensional polymer [Co(DCNT)
(H2O)]n (1), H2DCNT = 2,4-bis(4-carboxyphenylamino)-6-diethylamino-1,3,5-triazine. In the structure of 1, each DCNT2À has three
coordination sites, one nitrogen atom in the triazine ring coordinating to Co(II) and two carboxylates adopting l2-bridging mode, which
make the infinite Co(II) chains array uniformly and evenly toward crystallographic c-axis. Luminescent and magnetic properties of 1
were also studied.
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: Hydrothermal method; Coordination polymer; Luminescence; Magnetic property
The rational design and construction of new polymeric
compounds based upon assembly of metal ions and multi-
functional organic ligands are an increasingly interesting
research field due to their intriguing structural diversities
and potential applications in functional materials [1]. In
particular, the hydrothermal route is currently being devel-
oped in solid-state and coordination chemistry, for the
design of novel polymeric architectures. In this method,
structural motifs of these organic–inorganic hybrid systems
are closely related to the geometry and the number of coor-
dination sites provided by the ligand. Many works focused
on the use of N– or O– donor organic molecules to act as
exo-bidentate ligands to bridge metal ions, generating poly-
meric metal compounds with infinite chain structure and
two or three-dimensional network [2].
1,3,5-triazine (H2DCNT) [4]. The carboxyphenylamino
has been introduced into triazine ring, so that the versatile
coordination modes of carboxylate and triazine ring could
be utilized to provide new polymeric organic–inorganic
hybrid materials. There are some reported carboxylate tri-
azine-based ligands with three symmetrically substituted
sites used for construction of novel polymeric coordination
compounds, such as 1,3,5-triazine-2,4,6-triaminehexaacetic
acid [5], 2,4,6-tricarboxylato-1,3,5-triazine [6], 2,4,6-tri-
yltribenzoato-1,3,5-triazine [7], and 2,4,6-tri(4-carboxyphe-
nylamino)-1,3,5-triazine [8]. But polymeric compound
including carboxylate triazine-based ligand with two substi-
tuted sites is rarely reported. We demonstrate in this com-
munication construction of a three-dimensional polymer
[Co(DCNT)(H2O)]n (1) with novel topology Scheme 1.
The hydrothermal reaction of Co(NO3)2 Æ 6H2O and
H2DCNT yields purple crystals of [Co(DCNT)(H2O)]n
(1) [9]. All major peaks of experimental powder X-ray pat-
tern (XRPD) of compound 1 match quite well with that of
the simulated XRPD, indicating reasonable crystalline
phase purity. The antisymmetric and symmetric C@O
stretches in free ligand H2DCNT appear at 1549 cmÀ1
and 1421 cmÀ1, while the antisymmetric and symmetric
It is well known that chlorine atoms in cyanuric chloride
are easily replaced by other organic groups [3]. Using cyan-
uric chloride as reactant and controlling react ratio and
temperature, we have synthesized a new dicarboxylate
ligand, 2,4-bis(4-carboxyphenylamino)-6-diethylamino-
*
Corresponding author. Fax: +86 591 83792932.
E-mail address: wkc@fjirsm.ac.cn (K. Wu).
1387-7003/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2007.04.023

Y. Wei et al. / Inorganic Chemistry Communications 10 (2007) 910–913
911
Cl
N
N(C H )
2
5 2
H N
CO H
2
4
+
2
CH3COCH3
0 0
N
N
N
N
+
2NH(C2H5)2
45 0
C
C
Cl
Cl
Cl
Cl
N
C H
2
5
H
N
N
CO H
2
N
C H
2
5
N
N
CO2H. HCl
+
NH(C2H5)2. HCl
+
2
H2N
HN
CO H
2
Scheme 1. The structure and synthetic route of H2DCNT.
C@O stretching frequencies (1517 cmÀ1 and 1434 cmÀ1
,
respectively) for 1 suggests l2-bridging mode of the carbox-
ylate group. Thermal gravimetric analysis (TGA) of 1
under N2 atmosphere demonstrates that the first weight
loss corresponds to the loss of H2O (at the range of 174–
252 °C, 3.58% the weight loss observed; 3.62% theoretical).
DCNT2À begins to decompose at 420 °C. The thermal sta-
bility of 1 is comparable to that of high-thermal-stability
(up to 400 °C) coordination polymers with ligand 2,4,6-tri-
yltribenzoato-1,3,5-triazine in the literature [7a].
Fig. 2. Three-dimensional network structure of 1, viewed down the
crystallographic c-axis (hydrogen atoms were omitted for clarity).
Compound 1 possesses three-dimensional polymeric
structure. Fig. 1 shows coordination environment of Co(II)
and bonding mode of DCNT2À in compound 1. The coor-
dination geometry of Co(II) is a distorted octahedron com-
pleted by four carboxylato–oxygen atoms, one triazine
nitrogen atom and one water oxygen atom. Each DCNT2À
has three coordination sites, one triazine nitrogen atom
coordinating to Co(II) and two carboxylates adopting
l2-bridging mode which connect Co(II) centers to form
infinite wavy cobalt–carboxylate chains. Fig. 2 shows
three-dimensional polymeric network of compound 1.
The infinite wavy cobalt–carboxylate chains are linked
through coordination by two carboxylates and one triazine
nitrogen donor in DCNT2À, making compound 1 a three-
dimensional polymer. Interestingly the infinite wavy
cobalt–carboxylate chains array uniformly and evenly
toward crystallographic c-axis. As shown in geometric
topology (Fig. 3), distance of the neighboring cobalt–car-
2À
˚
boxylate chains is 11.22 A. The ligands DCNT arrange
Fig. 1. Coordination environment of Co(II) and coordination mode of
DCNT2À (hydrogen atoms were omitted for clarity). Color scheme: cyan
sphere, Co; light green sphere, C; blue sphere, N; red sphere, O. Selected
˚
bond lengths (A) and angles (°): Co–O1 2.136(6); Co–O2 2.176(3); Co–O3
2.074(3); Co–N1 2.249(4); O2–Co–O3 88.19(13); O2–Co–O3#1
174.61(15); N1–Co–O1 178.7(2). Symmetry code: #1 1Àx, y, z. (For
interpretation of the references to color in this figure legend, the reader is
referred to the web version of this article.)
Fig. 3. The geometric topology of 1 building on Co(II) and ligand
DCNT2À. (a) Viewed down the crystallographic c-axis, (b) viewed down
the crystallographic a-axis.

912
Y. Wei et al. / Inorganic Chemistry Communications 10 (2007) 910–913
100
chains linked by carboxylate array conformably toward
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
one direction in the three-dimensional network.
80
60
40
20
0
Acknowledgement
We gratefully acknowledge the financial support of Nat-
ural Science Foundation of China (Nos. 20173064 and
90203017).
μ
Appendix A. Supplementary material
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.inoche.2007.
04.023.
0
50
100
150
200
250
300
350
T / K
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