Synthesis, characterization and properties of series coordination polymers constructed from a biphenyl dicarboxylate and nitrogen-containing mixed ligands

Article abstract of DOI:10.1016/j.ica.2009.09.025

A series of coordination polymers have been prepared by the combination of flexible ligand 1,1′-biphenyl-2,2′-dicarboxylic acid (H₂dpa) and different types of nitrogen-containing ligands, with various metal ions such as Co(II), Zn(II) and Cd(II

Full text of DOI:10.1016/j.ica.2009.09.025

Inorganica Chimica Acta 362 (2009) 5203–5210
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Synthesis, characterization and properties of series coordination polymers
constructed from a biphenyl dicarboxylate and nitrogen-containing mixed ligands
*
Xinxin Xu, Xiaoxia Liu , Xia Zhang, Ting Sun
Department of Chemistry, College of Science, Northeast University, Shenyang 110004, PR China
a r t i c l e i n f o
a b s t r a c t
A series of coordination polymers have been prepared by the combination of flexible ligand 1,10-biphe-
nyl-2,20-dicarboxylic acid (H2dpa) and different types of nitrogen-containing ligands, with various metal
ions such as Co(II), Zn(II) and Cd(II). The single-crystal structure analyses reveal that the above complexes
possess different structure features with the introduction of different nitrogen-containing ligands. When
auxiliary linear ligand 4,40-bipyridine (4,40-bpy) is introduced, two-dimensional layered complex,
[Co2(dpa)2(4,40-bpy)2(H2O)]n (1) is formed. Whereas if chelating ligand, 1,10-phenanthroline (1,100-phen)
and 2,20-bipyridine (2,20-bpy) are introduced, one-dimensional complex [Zn(dpa)(1,100-phen)]n (2) and
discrete complexes [Co2(dpa)2(2,20-bpy)2(H2O)2] (3), [Co3(dpa)3(1,100-phen)6(H2O)2] (4), [Cd(dpa)(1,100-
phen)2][(H2dpa)2(H2O)2] (5) are synthesized. To our interest, 1 and 2 crystallize in homochiral space-
group. Furthermore, the magnetic property of complex 1 and the fluorescent properties of complexes 2
and 5 are studied.
Article history:
Received 2 January 2009
Received in revised form 23 July 2009
Accepted 9 September 2009
Available online 16 September 2009
Keywords:
Mixed ligands
Homochiral
Fluorescent property
Magnetic property
Crown Copyright Ó 2009 Published by Elsevier B.V. All rights reserved.
1. Introduction
around the two benzene groups make it quite a versatile ligand for
constructing novel coordination polymers [16–20], and (c) it dis-
During the past decade, the preparation of coordination poly-
mers with intriguing structures has attracted increasing interests
for the sake of potential applications, such as catalysis, magnetic,
functional electronic and gas separation [1–6]. Recently, there is
an increasing interest in coordination polymers built from flexible
bridging ligands [7,8]. Coordination polymers with diverse struc-
tures composed of different types of flexible ligands have been re-
ported, particularly those containing O-, N-, or S-donors [9,10]. The
biphenyl ligands bearing structural flexibility and conformation
freedom are good choice of O-donor ligands, and the flexible nature
of spacers allows these ligands to rotate when coordinate to metal
centers so as to conform to the coordination geometries of metal
ions [11,12]. Significant progress has been achieved in this area;
however, the factors that affect the formation of coordination poly-
mers constructed form flexible biphenyl ligands and the exploita-
tion of novel strategies are still comparatively less investigated.
Previous investigations including ours indicate that 2,20-
biphenyldicarboxylate (H2dpa) has a strong capability of affording
new coordination polymers for several reasons: (a) it has four po-
tential donor carboxylic oxygen atoms to coordinate to metal ions
with different connection modes [13–15], (b) the skew coordina-
tion orientation of the carboxylic group, the hindrance between
the 2,20-positioned carboxylic groups, and the nonlinear flexibility
plays strong reactive ability with d and f block metal ions [21–24].
Recently, studies reveal that coordination polymers constructed
by mixed ligands of pyridyl groups and carboxylic groups not only
incorporate interesting properties of different functional group but
also are more adjustable through changing one of the above two
organic ligands [25]. Despite the fact a lot of interesting complexes
have been constructed from mixed ligands, the systematic research
on this subject is less explored, since the structures are highly
influenced by the properties of ligands, coordination preference
of metal ions, and some very subtle factors, such as temperature
and counter ions [26,27]. In this article, to synthesis new coordina-
tion polymers based on mixed ligands as well as enrich the coordi-
nation chemistry of H2dpa, we introduce two types of nitrogen-
containing ligands to the metal-dpa system: one is linear 4,40-
bpy, the other is chelating ligand 1,100-phen or 2,20-bpy and syn-
thesized a series of coordination polymers exhibit various struc-
tural features and rich coordination modes of dpa ligand are
obtained.
2. Experimental
2.1. Materials and methods
All chemicals purchased were of reagent grade and used with-
out further purification. Elemental analyses (C, H, N) were per-
formed on a Perkin–Elmer 2400 CHN elemental analyzer. FT/IR
* Corresponding author. Tel.: +86 024 83689510; fax: +86 024 23600159.
E-mail address: xxliu@mail.neu.edu.cn (X. Liu).
0020-1693/$ - see front matter Crown Copyright Ó 2009 Published by Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2009.09.025

5204
X. Xu et al. / Inorganica Chimica Acta 362 (2009) 5203–5210
spectra were recorded in the range 4000–400 cmꢀ1 on an Alpha
Centaut FTIR spectrophotometer using a KBr pellet. TG analyses
were performed on Perkin–Elmer TGA7 instrument in flowing N2
with a heating rate of 10 °C minꢀ1. Photoluminescence spectra
were measuring using a FL-2T2 instrument (SPEX, USA) with
450-W xenon lamp monochromatized by double grating (1200 g/
mu).
Table 2
Selected bond lengths for complexes 1–5.
Complex 1
Co(1)–O(4)
2.031(2)
2.031(2)
2.083(3)
2.083(3)
2.092(4)
2.137(4)
2.041(3)
2.041(3)
2.075(2)
Co(2)–O(1)
Co(2)–O(7)
Co(2)–N(2)#1
Co(2)–O(3)
Co(2)–N(1)
Co(2)–O(5)
Co(3)–O(6)#2
Co(3)–N(4)#1
Co(3)–N(3)
2.052(2)
2.067(2)
2.091(3)
2.114(2)
2.121(3)
2.151(2)
2.075(2)
2.092(4)
2.113(4)
Co(1)–O(4)#3
Co(1)–O(10)
Co(1)–O(10)#3
Co(1)–N(5)
Co(1)–N(6)#4
Co(3)–O(9)#2
Co(3)–O(9)
2.2. Syntheses of complexes 1–5
Co(3)–O(6)
2.2.1. [Co2(dpa)2(4,40-bpy)2(H2O)]n (1)
Complex 2
Zn(1)–O(4)
Zn(1)–O(2)
Zn(1)–N(2)
Complex 1 was prepared from the mixture of Co(OAc)2ꢁ2H2O
(0.085 g, 0.40 mmol), H2dpa (0.194 g, 0.80 mmol), 4,40-bpy
(0.125 g, 0.80 mmol) in 8 ml H2O. The mixture was stirred for
20 min, and pH value was then adjusted to 5 with 1 M NaOH. After
transferred to a 23 ml Teflon-lined stainless steel bomb, the mix-
ture was kept at 170 °C under autogenously pressure for 4 days.
After cooling the reaction system to room temperature during
24 h, red block crystals of 1. For complex 1: yield: 59% (based on
Co). Anal. Calc. for C48H36N4O10Co2: C, 60.90; H, 3.83; N, 5.92.
Found: C, 60.85; H, 3.89; N, 6.03%. IR: 3314 (s), 3061 (s), 1578
(s), 1435 (s), 1377 (s), 1108 (m), 1046 (w), 1015 (m), 966 (w),
844 (m), 791 (m), 628 (w).
Complex 1 could also be obtained in various yields under the
following conditions: (1) Co(OAc)2ꢁ2H2O (0.40 mmol) + H2dpa
(0.80 mmol) + 4,40-bpy (0.80 mmol) + water (8 ml), 160 °C, 4 days;
(2) Co(OAc)2ꢁ2H2O (0.4 mmol) + H2dpa (0.80 mmol) + 4,40-bpy
(0.80 mmol) + water (8 ml), 180 °C, 4 days. The yields reacted at
180 °C are higher than that reacted at 160 and 170 °C.
1.959(2)
2.206(2)
2.063(2)
Zn(1)–O(3)
Zn(1)–N(1)
2.118(3)
2.113(3)
Complex 3
Co(1)–O(4)
Co(1)–O(5)
Co(1)–N(1)
1.985(2)
2.135(2)
2.165(2)
Co(1)–O(1)
Co(1)–N(2)
2.006(2)
2.122(2)
Complex 4
Co(1)–O(3)
Co(1)–O(1)
Co(1)–N(3)
Co(1)–N(2)
Co(1)–N(1)
Co(1)–N(4)
Co(3)–O(12)
Co(3)–O(10)
Co(3)–N(9)
2.044(3)
2.071(2)
2.126(3)
2.138(3)
2.171(4)
2.213(3)
2.038(3)
2.044(2)
2.121(3)
Co(2)–O(7)
Co(2)–O(5)
Co(2)–N(6)
Co(2)–N(7)
Co(2)–N(8)
Co(2)–N(5)
Co(3)–N(11)
Co(3)–N(12)
Co(3)–N(10)
2.052(3)
2.061(2)
2.130(3)
2.132(3)
2.184(3)
2.192(3)
2.126(3)
2.189(3)
2.213(4)
Complex 5
Cd(1)–O(1)#1
Cd(1)–N(1)
Cd(1)–N(2)
2.292(4)
2.343(4)
2.389(4)
Cd(1)–O(1)
Cd(1)–N(1)#1
Cd(1)–N(2)#1
2.292(4)
2.343(4)
2.389(4)
2.2.2. [Zn(dpa)(1,100-phen)]n (2)
Symmetry transformations used to generate equivalent atoms for complex 1: #1 x,
y ꢀ 1, z; #2 ꢀx + 1, y, ꢀz + 1; #3 ꢀx, y, ꢀz; #4 x, y + 1, z.
Symmetry transformations used to generate equivalent atoms for complex 5: #1
ꢀx + 1, y, ꢀz, +3/2.
The mixture of Zn(OAc)2ꢁ2H2O (0.088 g, 0.40 mmol), H2dpa
(0.194 g, 0.80 mmol), 1,100-phen (0.144 g, 0.80 mmol), and 6 ml
H2O was stirred for 20 min, and then the pH value was adjusted
to 5 with 1 M NaOH. After stirring for another 20 min, the mixture
was transferred to a 23 ml Teflon-lined stainless steel bomb and
kept at 170 °C under autogenously pressure for 4 days. The reac-
tion system was cooled to room temperature during 24 h. A large
amount of colorless block crystals of 2 were obtained. Yield: 46%
(based on Zn). Anal. Calc. for C26H16N2O4Zn: C, 64.28; H, 3.32; N,
5.77. Found: C, 64.18; H, 3.46; N, 5.63%. IR: 1573 (s), 1542 (w),
1521 (s), 1455 (w), 1382 (s), 1360 (w), 1130 (m), 1040 (w), 848
(s), 769 (m), 618 (m), 554 (w).
This complex could also be obtained in low yields by the solvo-
thermal reactions of Zn salts, H2dpa, and 1,100-phen with different
molar ratios in 10 ml of ethanol or methanol and other solvent.
2.2.3. [Co2(dpa)2(2,20-bpy)2(H2O)2] (3)
Complex 3 was prepared from the mixture of Co(OAc)2ꢁ2H2O
(0.085 g, 0.40 mmol), H2dpa (0.194 g, 0.80 mmol), 2,20-bpy
Table 1
Crystal data and structure refinement for complexes 1–5.
1
2
3
4
5
Formula
FW
Crystal system
Space group
a (Å)
C48H36Co2N4O10
946.67
monoclinic
C2
22.540(5)
11.301(2)
18.824(4)
90
119.84(3)
90
C26H16N2O4Zn
485.78
C48H36Co2N4O10
946.67
monoclinic
P21=c
11.015(2)
9.5133(19)
20.765(4)
90
104.57(3)
90
C114H76Co3N12O14
2014.66
triclinic
C66H48CdN4O14
1233.48
monoclinic
C2=c
32.628(7)
9.998(2)
18.122(4)
90
107.11(3)
90
5650(2)
4
orthorhombic
P212121
9.4909(19)
11.601(2)
18.547(4)
90
90
90
2042.1(7)
4
1.580
ꢀ
P1
16.738(3)
18.302(4)
18.349(4)
113.89(3)
102.96(3)
108.34(3)
4459.6(15)
2
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
4159.1(15)
4
1.512
2106.0(7)
2
1.493
Z
qcalcd (g/cm3)
1.500
1.450
Data/restraints/parameters
Rint
S
7040/5/596
0.0357
0.864
3577/0/298
0.0482
0.920
3625/2/280
0.0487
1.030
15498/4/1290
0.0309
1.179
4944/2/375
0.0415
1.149
R1 [I > 2
wR2 [I > 2
r
(I)]
(I)]
0.0323
0.0764
0.0321
0.0821
0.0448
0.1352
0.0532
0.1604
0.0677
0.2027
r
Flack ꢂ parameter
0.036(10)
0.034(18)
P
P
P
P
2
2 1=2
Note: R1
¼
kFojj ꢀ jFck= jFoj; wR2
¼
½wðF2o ꢀ Fc2Þ ꢃ= ½wðF2oÞ ꢃ
.

X. Xu et al. / Inorganica Chimica Acta 362 (2009) 5203–5210
5205
(0.125 g, 0.80 mmol), and 8 ml H2O, was stirred for 20 min, and
then the pH value was adjusted to 4 with 1 M NaOH. After stirring
for another 20 min, the mixture was transferred to a 23 ml Teflon-
lined stainless steel bomb and kept at 180 °C under autogenously
pressure for 4 days. The reaction system was cooled to room tem-
perature during 24 h. A large amount of red block crystals of 3 were
obtained. Yield: 52% (based on Co). Anal. Calc. for C48H36N4O10Co2:
C, 60.90; H, 3.83; N, 5.92. Found: C, 61.02; H, 3.86; N, 5.99%. IR:
3269 (s), 3118 (s), 1571 (s), 1465 (m), 1378 (s), 1286 (w), 1138
(m), 1040 (w), 947 (w), 861 (s), 769 (m), 608 (m), 563 (w).
Complex 3 could also be obtained in low yields (<20%) by the
hydrothermal reactions of Co(OAc)2ꢁ2H2O, H2dpa and 2,20-bpy
with lower the starting pH value.
during 24 h, and red block crystals of 4 were obtained. Yield: 54%
(based on Co). Anal. Calc. for C114H76N12O14Co3: C, 67.96; H, 3.80;
N, 8.34. Found: C, 67.86; H, 3.91; N, 8.29%. IR: 3256 (s), 3094 (s),
1541 (s), 1345 (s), 1268 (w), 1179 (m), 977 (w), 825 (m), 784
(m), 708 (w), 677 (w), 561 (w).
This complex could also be obtained in various yields with the
following different molar ratios in 8 ml of water. (1)
Co(OAc)2ꢁ2H2O/H2dpa/1,100-phen 1:2:1, (2) Co(OAc)2ꢁ2H2O/
H2dpa/1,100-phen 2:2:1, (3) Co(OAc)2ꢁ2H2O/H2dpa/1,100-phen
1:2:4, and (4) Co(OAc)2ꢁ2H2O/H2dpa/1,100-phen 1:4:4.
2.2.5. [Cd(dpa)(1,100-phen)2][(H2dpa)2(H2O)2] (5)
Complex 5 was prepared from a mixture of Cd(OAc)2ꢁ2H2O
(0.107 g, 0.40 mmol), H2dpa (0.194 g, 0.80 mmol), 2,20-bpy
(0.125 g, 0.80 mmol) and 8 ml H2O. The mixture was stirred for
15 min and sealed in a 23 ml Teflon-lined stainless steel bomb.
The bomb was kept at 150 °C under autogenously pressure for
3 days. The reaction system was then cooled to room temperature
during 24 h, and yellow block crystals of 5 were obtained. Yield:
60% (based on Cd). Anal. Calc. for C66H48N4O14Cd: C, 64.26; H,
3.92; N, 4.54. Found: C, 64.33; H, 3.86; N, 4.48%. IR: 3239 (s),
2.2.4. [Co3(dpa)3(1,100-phen)6(H2O)2] (4)
Complex 4 was prepared from a mixture of Co(OAc)2ꢁ2H2O
(0.085 g, 0.40 mmol), H2dpa (0.194 g, 0.80 mmol), 1,100-phen
(0.144 g, 0.80 mmol) and 8 ml H2O. The mixture was stirred for
15 min and sealed in a 23 ml Teflon-lined stainless steel bomb.
The bomb was kept at 165 °C under autogenously pressure for
3 days. The reaction system was then cooled to room temperature
Fig. 1. (a) The fundamental unit of complex 1. (b) The two-dimensional layer structure of complex 1.

5206
X. Xu et al. / Inorganica Chimica Acta 362 (2009) 5203–5210
3109 (s), 1551 (s), 1358 (s), 1336(s), 1288 (w), 1184 (m), 972 (w),
827 (m), 783 (w), 712 (w), 677 (w), 563 (w).
Complex 5 could also be obtained in about the same yields by
the hydrothermal if we use other based adjusting the pH value,
such as pyridine, KOH.
Anisotropic thermal parameters were used to refine all non-hydro-
gen atoms. Carbon-bound hydrogen atoms were placed in geomet-
rically calculated positions; oxygen-bound hydrogen atoms were
located in the difference Fourier maps and kept in that position.
Further details of the X-ray structural analysis are given in Table
1. Selected bond lengths are listed in Table 2.
2.3. X-ray crystallography
Single-crystals of complexes 1–5 were glued on glass fibers,
3. Result and discussion
respectively. Data were collected on a Rigaku R-AXIS RAPID IP dif-
fractometer at 293 K using graphite monochromated Mo K
a
radia-
3.1. Crystal structure of complexes 1–5
tion (k = 0.71073 Å) and IP technique. Empirical absorption
correction was applied. The structures were solved by the direct
methods and refined by the full-matrix least-squares method on
F2 using the SHELXTL 97 crystallographic software package [28,29].
According to single-crystal X-ray diffraction, complex 1 pos-
sesses a fundamental unit which consists of three crystallo-
graphic distinct Co atoms, two 4,40-bpy ligands, three dpa
Fig. 2. (a) The fundamental unit of complex 2. (b) One-dimensional helical chain structure of complex 2. (c) Two-dimensional supramolecular layer network of complex 2.

X. Xu et al. / Inorganica Chimica Acta 362 (2009) 5203–5210
5207
ligands and one water molecule as shown in Fig. 1a. Co1 connects
with two oxygen atoms from two dpa ligands, two nitrogen
atoms from different 4,40-bpy ligands, the other two coordination
sites is occupied by water. The Co–O bond distances are 2.031
and 2.083 Å, Co–N bond distance is 2.138 Å. This results a dis-
torted octahedral coordination mode. Unlike Co1, Co2 connects
four carboxylic oxygen atoms from two dpa ligands, two nitrogen
atoms from two 4,4-bpy ligands. The Co–O bond distances range
from 2.052 to 2.151 Å, the average Co–N bond distance is 2.106 Å,
and the O–Co–O bond angles are 78.39–176.18°. Co3 adopts the
same kind of coordination mode with Co1, but with different
bond lengths and bond angles. The two carboxylic groups in
dpa ligand adopt two kinds of connection mode, one is monoden-
tate, the other is bridging. All the dpa ligands adopt right-handed
coordination mode, connects the adjacent Co atoms together and
form one-dimensional right-handed (P) helix. The right-handed
(P) helixes are linked together with 4,4-bpy ligands and form
two-dimensional homochiral layer structure as shown in
Fig. 1b. To our interest, complex 1 crystallizes in a chiral space
group. To our knowledge, although some complexes with helical
structures had been synthesized from dpa ligands, homochiral
complexes had never been synthesized from dpa ligand [15].
Therefore, complex 1 is the first homochiral complex constructed
by dpa ligand.
Fig. 3. (a) The fundamental unit of complex 3. (b) Three-dimensional supramolecular network of the complex 3.

5208
X. Xu et al. / Inorganica Chimica Acta 362 (2009) 5203–5210
Single-crystal X-ray diffraction analysis reveals that complex 2
the oxygen atoms, which lead to the whole chirality of the two
complexes.
exhibits a one-dimensional chiral helical chain like structure. In
the fundamental unit, there exists only one crystallographic inde-
pendent Zn atom, which adopts tetrahedral-pyramidal coordina-
tion mode as shown in Fig. 2a. It connects with three oxygen
atoms from two dpa ligands with Zn–O bond distances ranging
from 1.959 to 2.206 Å, and the O–Zn–O bond angles range from
60.82° to 104.38°. Two nitrogen atoms from 1,100-phen occupy
the other two coordination sites with the average Zn–N bond dis-
tance of 2.088 Å. The two carboxylic groups from dpa ligands con-
nect Zn atoms together and form homochiral one-dimensional
right-handed (P) helix as shown in Fig. 2b, which results the chiral-
ity in this complex. These one-dimensional chains are further ex-
For complex 3, there also exists only one crystallographic
independent Co atom, which adopts square pyramidal coordina-
tion mode as shown in Fig. 3a. The Co atom connects with two
oxygen atoms from two dpa ligands with average Co–O bond
distance 1.99 Å, two nitrogen atoms from 2,20-bpy ligand, and
the last coordination site is occupied by one aqua ligand. With
such kind of connection mode, two Co atoms, two dpa ligands,
and two 2,20-bpy ligands form a large ring. With the
p–p inter-
actions between 2,20-bpy and dpa ligands, these rings are further
extended to two-dimensional layers. With the same kind of
weak interactions, two-dimensional layers are further connected
to form three-dimensional supramolecular network as shown in
Fig. 3b. The distances of the adjacent phenyl rings range from
3.47 to 3.56 Å.
tended into two-dimensional sheets through the p–p interactions
from the phenyl rings of the 1,100-phen and dpa ligands. The dis-
tances of the adjacent phenyls range from 3.43 to 3.57 Å as shown
in Fig. 2c.
The asymmetric unit of complex 4 contains three Co atoms. Co1
connects with two carboxylic oxygen atoms from one dpa ligand
four nitrogen atoms from two 1,100-phen ligands, the Co–O bond
distances are 2.045 and 2.071 Å, the Co–N bond distances are in
In homochiral complexes 1 and 2, the screw of carboxylate
groups resulted in the formation of the helical chain, and then
the homochiral information can be effectively transferred through
Fig. 4. (a) The fundamental unit of complex 4. (b) The fundamental unit of complex 5.

X. Xu et al. / Inorganica Chimica Acta 362 (2009) 5203–5210
5209
the range of 2.126 and 2.214 Å. This results a discrete unit of
10
9
8
7
6
5
4
3
2
[Co(dpa)(1,100-phen)2], in which Co1 adopts distorted octahedral
coordination mode. Co2 and Co3 adopt the same kind of coordina-
tion mode with Co1, but with different bond lengths and bond an-
gles as shown in Fig. 4a. To our interests, these three kind of
[Co(dpa)(1,100-phen)2] units exhibit two kind of configuration,
35
30
25
20
15
10
5
Co1 and Co2 adopt
D configuration, while Co3 uses K mode.
Like complex 4, complex 5 also exhibits discrete structural fea-
ture. There exist only one crystallographic independent Cd atom in
the fundamental unit. Cd1 adopts two carboxylic oxygen atoms
from dpa ligand, four nitrogen atoms from two 1,100-phen ligands.
The Cd–O bond distance is 2.239 Å, Cd–N bond distances are 2.343
and 2.389 Å, respectively, which results a distorted octahedron
coordination mode. Besides the [Cd(dpa)(1,100-phen)2] unit, there
exist a free H2dpa and water molecule in the fundamental unit
as shown in Fig. 4b.
0
0
50 100 150 200 250 300
T (K)
0
50
100
150
T (K)
200
250
300
3.2. Thermo gravimetric analyses
Fig. 6. The magnetic property of complex 1.
In order to examine the thermal stabilities of the five com-
plexes, thermal gravimetric (TG) analyses were carried out. Com-
plex 1 exhibits two steps of weight losses. The first weight loss
about 1.86% occurs in the range of 110–153 °C, corresponding to
the removal of water (calcd. 1.90%). The second weight loss is
about 83.73% from 271 to 439 °C, assigned to the loss of organic li-
gands (calcd. 83.75%). The curve of complex 2 also exhibits one-
step weight loss in the range 262–430 °C (86.42%), corresponding
to the loss of organic ligands (calcd. 86.54%). Like complex 1, com-
plex 3 shows two steps weight losses; the weight loss about 3.71%
from 109 to 163 °C represents the loss of water (calcd. 3.80%). The
second weight loss about 69.85% from 304 to 420 °C represents the
loss of organic ligands (calcd. 83.75%). Complex 4 also displays two
steps weight loss, the first weight loss about 1.66% from 71 to
112 °C shows the release of water, and the second about 89.48%
from 343 to 427 °C exhibits the loss of organic ligands. These are
in agreement with the calculated values (1.79% and 89.44%). The
TG curve of complex 5 shows that chemical decomposition starts
at 81 °C and ends at 460 °C with the weight loss of 3.01% and
87.79% are equivalent to the loss of water and organic molecules
(calcd. 2.92% and 87.94%).
observed that complexes 2 and 5 exhibit photoluminescence with
emission maximum at ca. 387 and 381 nm upon excitation at 325
and 337 nm. According to the previous reports [30], these emission
bands could be assigned to the emission of ligand-to-metal charge
transfer (LMCT).
3.4. Magnetic property
The temperature dependence of the magnetic susceptibility for
complex 1 was investigated in the temperature range from 1.99 to
300 K under a magnetic field of 1000 G. The variation of
vꢀM1 with T for complex 1 is shown in Fig. 6. At 300 K, the
9.67 cm3 K molꢀ1. As temperature is lowered, the
MT value de-
creases continuously to a value of 2.45 cm3 K molꢀ1 at 2 K. Such
a behavior of MT curve indicates a mainly antiferromagnetic
v
MT and
vMT is
v
v
interaction in 1. The variation of the vM with temperature follows
the Curie–Weiss equation because of the linear relationship be-
tween vꢀM1 and T. The Curie constant and Weiss temperature are
found to be 10.11 cm3 K molꢀ1 and ꢀ8.03 K. The negative Weiss
temperature further indicates the antiferromagnetic interactions
between Co(II) ions [31–33].
3.3. Fluorescent property
The photoluminescence properties of complex 2 and complex 5
in the solid state at room temperature are shown in Fig. 5. It can be
4. Conclusions
Here, we synthesized five new coordination polymers gener-
ated from mixed ligand systems of H2dpa and various nitrogen-
containing ligands under hydrothermal condition. Among the com-
plexes we synthesized, complex 1 exhibits two-dimensional layer
structure, complex 2 exhibits one-dimensional chain like structure,
complexes 3–5 shows discrete structures, complexes 1 and 2 crys-
tallized in homochiral spacegroup. Our findings will enrich the
coordination chemistry and crystal engineering study of dpa and
mixed ligands. We studied the magnetic property of complex 1
and the fluorescent properties of complexes 2 and 5. Furthermore,
this work prompts us to synthesize more complexes from flexible
organic ligands.
Complex 2
Complex 5
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.ica.2009.09.025.
CCDC 701330, 701331, 710384, 710385 and 710386 contain the
supplementary crystallographic data for complexes 1, 2, 3, 4 and 5.
These data can be obtained free of charge from The Cambridge
350
400
450
500
550
600
650
700
Wavelength (cm-1)
Fig. 5. The fluorescent spectra of complexes 2 and 5.

5210
X. Xu et al. / Inorganica Chimica Acta 362 (2009) 5203–5210
[15] R.H. Wang, Y.F. Zhou, Y.Q. Sun, D.Q. Yuan, L. Han, B.Y. Lou, B.L. Wu, M.C. Hong,
Cryst. Growth Des. 5 (2005) 251.
[16] Y.B. Wang, X.J. Zheng, W.J. Zhuang, L.P. Jin, Eur. J. Inorg. Chem. (2003) 1355.
[17] J.Y. Lu, V. Schauss, Inorg. Chem. Commun. 6 (2003) 1332.
[18] J.M. Rueff, S. Pillet, N. Claiser, G. Bonaventure, M. Souhassou, P. Rabu, Eur. J.
Inorg. Chem. (2002) 895.
[19] X.X. Xu, Y. Lu, E.B. Wang, Y. Ma, X.L. Bai, Cryst. Growth Des. 6 (2006) 2029.
[20] D.C. Pascal, B. Richard, F. Hemler, Dalton Trans. (2006) 586.
[21] R.H. Wang, Y.Q. Gong, L. Han, D.Q. Yuan, B.Y. Lou, B.L. Wu, M.C. Hong, J. Mol.
Struct. 784 (2006) 1.
[22] F.Y. Lian, R.H. Wang, L. Han, F.L. Jiang, M.C. Hong, Z. Anorg. Allg. Chem. 631
(2005) 2485.
[23] R.H. Wang, L. Han, Y.Q. Sun, Y.Q. Gong, D.Q. Yuan, M.C. Hong, J. Mol. Struct. 694
(2004) 79.
[24] R.H. Wang, F.L. Jiang, L. Han, Y.Q. Gong, Y.F. Zhou, M.C. Hong, J. Mol. Struct. 699
(2004) 79.
[25] J.M. Rueff, S. Pillet, G. Bonaventure, M. Souhassou, P. Rabu, Eur. J. Inorg. Chem.
(2003) 4173.
[26] Q. Miao, M.L. Hu, F. Chen, Acta Cryst. E 60 (2004) m1314.
[27] X.X. Xu, Y. Lu, E.B. Wang, Y. Ma, X.L. Bai, J. Mol. Struct. 825 (2006) 124.
[28] G.M. Sheldrick, SHLEXL97, Program for Crystal Structure Refinement, University
of Göttingen, Germany, 1997.
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_re-
quest/cif.
References
[1] N. Rosi, J. Kim, B. Chen, M. Eddaoudi, M. O’Keeffe, O.M. Yaghi, J. Am. Chem. Soc.
127 (2005) 1504.
[2] C.M. Zaleski, E.C. Depperman, J.W. Kampf, M.L. Kirk, V.L. Pecoraro, Angew.
Chem., Int. Ed. 43 (2004) 3912.
[3] H. Oshio, M. Nihei, S. Koizumi, T. Shiga, H. Nojiri, M. Nakano, N. Shirakawa, M.
Akatsu, J. Am. Chem. Soc. 127 (2005) 4568.
[4] D. Li, T. Wu, X.P. Zhou, R. Zhou, X.C. Huang, Angew. Chem., Int. Ed. 44 (2005)
4175.
[5] D.L. Long, R.J. Hill, A.J. Blake, N.R. Champness, P. Hubberstey, C. Wilson, M.
Schröder, Chem. Eur. J. 11 (2005) 1384.
[6] L. Pan, D.H. Olson, L.R. Ciemnolonski, R. Heddy, J. Li, Angew. Chem., Int. Ed. 45
(2006) 616.
[7] A. Mishra, W. Wernsdorfer, K.A. Abboud, G. Christou, J. Am. Chem. Soc. 126
(2004) 15648.
[8] H. Miyasaka, T. Nezu, K. Sugimoto, K. Sugiura, M. Yamashita, R. Clérac, Chem.
Eur. J. 11 (2005) 1592.
[9] V. Marvaud, C. Decroix, A. Scuiller, C. Guyard-Duhayon, J. Vaissermann, F.
Gonnet, M. Verdaguer, Chem. Eur. J. 9 (2003) 1677.
[10] S. Noro, H. Miyasaka, S. Kitagawa, T. Wada, T. Okubo, M. Yamashita, T. Mitani,
Inorg. Chem. 133 (2005) 44.
[11] L.M.C. Beltran, J.R. Long, Acc. Chem. Res. 38 (2005) 325.
[12] J.P. Zhang, Y.Y. Lin, X.C. Huang, X.M. Chen, J. Am. Chem. Soc. 127 (2005) 5495.
[13] R.H. Wang, M.C. Hong, J.H. Luo, R. Cao, J.B. Weng, Chem. Commun. (2003) 1018.
[14] R.H. Wang, M.C. Hong, J.H. Luo, R. Cao, J.B. Weng, Eur. J. Inorg. Chem. (2002)
2082.
[29] G.M. Sheldrick, SHLEXL97, Program for Crystal Structure Solution, University of
Göttingen, Germany, 1997.
[30] P.X. Yin, J. Zhang, J.K. Cheng, Z.J. Li, Y.G. Yao, Inorg. Chem. Commun. 9 (2006)
541.
[31] J.M. Rueff, N. Masciocchi, P. Rabu, A. Sironi, A. Skoulios, Eur. J. Inorg. Chem.
(2001) 2843.
[32] J.M. Rueff, N. Masciocchi, P. Rabu, A. Sironi, A. Skoulios, Chem. Eur. J. 8 (2002)
1813.
[33] A. Ray, J. Chakraborty, B. Samanta, S. Thakurta, C. Marschner, M.S.E. Fallah, S.
Mitra, Inorg. Chim. Acta 361 (2008) 1850.