New coordination polymers from 1D chain, 2D layer to 3D framework constructed from 1,2-phenylenediacetic acid and 1,3-bis(4-pyridyl)propane flexible ligands

Article abstract of DOI:10.1016/j.jssc.2011.04.002

The hydrothermal reactions of Cd, Zn, or Cu(II) acetate salts with H ₂PHDA and BPP flexible ligands afford three new coordination polymers, including [Cd(PHDA)(BPP)(H₂O)]_n (1), [Zn(PHDA)(BPP)]_n (2), and [Cu₂(PHDA)₂(BPP)] _n (3) (H₂PHDA=1,2-phenylenediacetic acid, BPP=1,3-bis(4-pyridyl)propane). The single-crystal X-ray diffractions reveal that all three complexes feature various metal carboxylate subunits extended further by the BPP ligands to form a diverse range of structures, displaying a remarked structural sensitivity to metal(II) cation. Complex 1 containing PHDA-bridged binuclear cadmium generates 1D double-stranded chain, complex 2 results in 2D→2D interpenetrated (4,4) grids, and complex 3 displays a 3D self-penetrated framework with 4⁸6⁶8 rob topology. In addition, fluorescent analyses show that both 1 and 2 exhibit intense blue-violet photoluminescence in the solid state.

Full text of DOI:10.1016/j.jssc.2011.04.002

Journal of Solid State Chemistry 184 (2011) 1387–1392
Contents lists available at ScienceDirect
Journal of Solid State Chemistry
journal homepage: www.elsevier.com/locate/jssc
New coordination polymers from 1D chain, 2D layer to 3D framework
constructed from 1,2-phenylenediacetic acid and 1,3-bis(4-pyridyl)propane
flexible ligands
Ling-Yun Xin, Guang-Zhen Liu n, Li-Ya Wang
College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang 471022, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
The hydrothermal reactions of Cd, Zn, or Cu(II) acetate salts with H2PHDA and BPP flexible ligands afford
three new coordination polymers, including [Cd(PHDA)(BPP)(H2O)]n (1), [Zn(PHDA)(BPP)]n (2), and
[Cu2(PHDA)2(BPP)]n (3) (H2PHDA¼1,2-phenylenediacetic acid, BPP¼1,3-bis(4-pyridyl)propane). The
single-crystal X-ray diffractions reveal that all three complexes feature various metal carboxylate
subunits extended further by the BPP ligands to form a diverse range of structures, displaying a
remarked structural sensitivity to metal(II) cation. Complex 1 containing PHDA-bridged binuclear
cadmium generates 1D double-stranded chain, complex 2 results in 2D-2D interpenetrated (4,4) grids,
and complex 3 displays a 3D self-penetrated framework with 48668 rob topology. In addition, fluorescent
analyses show that both 1 and 2 exhibit intense blue-violet photoluminescence in the solid state.
& 2011 Elsevier Inc. All rights reserved.
Received 31 December 2010
Received in revised form
30 March 2011
Accepted 3 April 2011
Available online 14 April 2011
Keywords:
Coordination polymer
Penetrated network
Flexible dicarboxylate
N-donor ligand
Fluorescent analysis
1. Introduction
[40–45]. Thus, the flexibility of the ligand can afford a good
opportunity to enrich the structural and functional diversities of
As an important branch in the field of supramolecular chem-
istry and crystal engineering, the design and assembly of metal–
organic coordination frameworks (MOFs) have stimulated the
interests of chemists over the past few decades [1–5], not only
because of their intriguing network topologies [6], but also the
possible application for such compounds in areas such as separa-
tion, catalysis, ion exchange, gas storage, etc. [7–10]. However,
the effective and facile approach for the synthesis of such
complexes is still the appropriate choice of well-designed organic
ligands as linkers with metal ions or clusters as nodes due to their
unclear formation mechanisms [11–14].
To date, most of the organic ligands used in MOFs chemistry
are limited to a rigid aromatic carboxylate and/or a N-containing
ligand [15–24], whereas the role of a flexible carboxylate ligand is
somewhat ignored. Compared to rigid ligands, using flexible ones
to construct coordination polymers seem more difficult and
developing systematic methodologies of synthesis materials from
prior design structure via flexible ligands are still a great chal-
lenge [25], which may be attributed to their unpredicted struc-
tures. However, flexible molecules can easily adjust their
conformations to meet the coordination requirement of the metal
ion [26–39] and may prone to promote helical or looped struc-
tural motifs through which other organic linkers can penetrate
MOFs and provide the further understanding of the directional
synthesis of target coordination polymers. It is therefore an
important aspect worthwhile paying attention to, and is the
potential for erecting some signposts toward future research on
predicted and pre-designed coordination polymers.
With these considerations in mind, our theme is the controllable
synthesis of penetrated metal–organic networks by the use of flexible
ligands. The simultaneous employment of conformationally flexible
ligands such as phenylenediacetate (H2PHDA) and 1,3-bis(4-pyridyl)-
propane (BPP) could thus conceivably act in tandem to foster
penetrated coordination polymer topologies. In this work, systematic
studies have been carried out in our laboratory by the reaction of Cd,
Zn, or Cu(II) acetate salts with the H2PHDA and BPP flexible ligands,
and producing three coordination complexes with the range of
structural dimensionalities from 1D double-stranded chain, Cd(PHDA)
(BPP)(H2O)]n (1), 2D-2D interpenetrated layer, [Zn(PHDA)(BPP)]n (2)
to 3D self-penetrated framework, [Cu2(PHDA)2(BPP)]n (3). The details
of their synthesis condition, coordination structure, and luminescence
are reported below.
2. Experimental
2.1. Materials and physical measurements
n Corresponding author. Fax: þ86 379 65511205.
E-mail address: gzliu@yahoo.com.cn (G.-Z. Liu).
All reagents used in these syntheses were of analytical grade and
used as purchased without further purification. Elemental analyses
0022-4596/$ - see front matter & 2011 Elsevier Inc. All rights reserved.
doi:10.1016/j.jssc.2011.04.002

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L.-Y. Xin et al. / Journal of Solid State Chemistry 184 (2011) 1387–1392
(C, H, N) were performed on a Vario EL III elemental analyzer.
Infrared spectra were recorded on a VECTOR-22 spectrophotometer
within 400–4000 cmꢀ1 using the samples prepared as pellets with
KBr. Luminescence spectra were performed on a Hitachi F-4500
fluorescence spectrophotometer at room temperature.
2.5. X-ray crystallography
Suitable single crystals of 1–3 were mounted on a Bruker
Smart APEX II CCD diffractometer equipped with graphite-mono-
chromated Mo Ka radiation (
l¼0.071073 nm) by using F/o scan
technique at room temperature. Semi-empirical absorption cor-
rections were applied using SADABS. The structures were solved
using direct method and refined by full-matrix least-squares on
F2. All non-hydrogen atoms were refined anisotropically, and
hydrogen atoms were located from the difference map, and then
added geometrically. All calculations were performed using the
SHELXTL-97 program package [46–48]. Crystal data and experi-
mental details for compounds 1–3 are presented in Table 1.
Selected bond distances and angles are listed in Table S1.
2.2. Synthesis of [Cd(PHDA)(BPP)(H2O)]n (1)
The mixtures of H2PHDA (0.1 mmol, 19.4 mg), BBP (0.2 mmol,
39.7 mg), Cd(OAC)2 ꢁ 2 H2O (0.1 mmol, 26.7 mg), NaOH (0.1 mmol),
N,N0-dimethylformamide (DMF, 4.0 ml), and H2O (4.0 ml) were
placed in a 23 ml Teflon liner stainless steel reactor. The vessel
was heated to 120 1C for 4 days, then cooled at 5 1C hꢀ1 to room
temperature. Colorless crystals were obtained, and further crystals
were filtered off, washed with mother liquid, and dried under
ambient conditions. Yield 53%. Elemental analysis calcd (%) for
3. Result and discussion
C23H24CdN2O5: C 53.04, H 4.64, N 5.38 Found: C 53.27, H 4.82,
N 5.26.
3.1. Synthesis and IR characterization
Hydrothermal method has been extensively explored as an
effective and powerful tool in the self-assembly of MOFs, although
the mechanism is not completely clear so far [49]. As is known, there
are a variety of parameters such as the pH value, temperature, the
molar ratio of the reactant and reactant solvent, which can exert a
profound influence on the final reaction outcome. In our experiment,
the hydrothermal reactions of compound 1–3 were carried out in
different solvent, the molar ratio, and pH values. It was found that the
compound 1 and 2 may be the favored products with adding the
0.1 mmol NaOH and DMF as the solvent (DMF:H2O¼1:1), which
proved the 1 and 2 seem sensitive to the pH value and solvent.
However, the compound 3 was produced in aqueous solution
without the NaOH.
The IR spectra of 1–3 show the sharp characteristic bands
of dicarboxylate groups in the usual region at 1613–1630
and 1485–1500 cmꢀ1 for the asymmetric stretching and the
1363–1393 cmꢀ1 for the symmetric stretching. Features corre-
sponding to pyridyl ring puckering mechanisms are evident
in the region 850 and 600 cmꢀ1. The broad bands in the area of
ꢂ3400–3200 cmꢀ1 in compound 2 belong to the O–H stretching
2.3. Synthesis of [Zn(PHDA)(BPP)]n (2)
Compound 2 was synthesized in a similar way as that
described for 1, except that Zn(OAC)2 ꢁ 2H2O(0.1 mmol, 21.9 mg)
replaced the metal center. Yield 46%. Elemental analysis calcd (%)
for C23H22ZnN2O4: C 60.61, H 4.86, N 6.14 Found: C 60.56, H 4.92,
N 6.20.
2.4. Synthesis of [Cu2(PHDA)2(BPP)]n (3)
Compound 3 was prepared by using H2PHDA (0.2 mmol,
38.8 mg), BBP (0.1 mmol, 19.8 mg), Cu(OAC)2 ꢁ 2 H2O (0.1 mmol,
20.0 mg) and H2O (8 ml) which were placed in a 23 ml Teflon
liner stainless steel reactor. The vessel was heated to 120 1C for
4 days, then cooled at 5 1C hꢀ1 to room temperature. Blue crystals
were obtained and crystals were filtered off, washed with water
liquid, and dried under ambient conditions. Yield 39%. Elemental
analysis calcd (%) for C16.5H15CuNO4: C 55.85, H 4.26, N 3.95
Found: C 55.88, H 4.32, N 3.89.
Table 1
Crystal data and structure refinement parameters for 1–3.
1
2
3
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
C23H24CdN2O5
520.84
C23H22ZnN2O4
455.80
C16.5H15CuNO4
354.83
296(2)
296(2)
296(2)
Triclinic
Pꢀ1
Monoclinic
P2(1)/c
Orthorhombic
Pccn
12.5326(11)
10.4461(13)
11.753(4)
˚
a (A)
13.1476(12)
14.7948(13)
16.919(2)
28.513(10)
9.064(3)
˚
b (A)
12.3974(15)
˚
c (A)
a (deg.)
75.6240 (10)
70.8980(10)
87.1140(10)
2230.2(3)
90.00
90.00
110.7200(10)
90.00
90.00
b
g
(deg.)
(deg.)
90.00
3
2049.4(4)
3037.7(18)
˚
Volume (A )
Crystal size (mm)
0.23 ꢃ 0.21 ꢃ 0.19
0.39 ꢃ 0.38 ꢃ 0.27
0.21 ꢃ 0.06 ꢃ 0.05
Z
4
4
8
Dcalc (g cmꢀ3
)
1.551
1.477
1.552
m
(mmꢀ1
F(0 0 0)
range (deg.)
)
1.015
1.231
1.456
1056
944
1456
2.39 to 25.50
17124
2.41 to 25.50
12927
2.76 to 25.50
21298
y
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness-of-fit
8236 [R(int)¼0.0181]
8236/0/559
1.080
3765 [R(int)¼0.0243]
3765/0/271
1.045
2822 [R(int)¼0.1221]
2822/0/204
1.021
Final R indices [I42
R indices (all data)
s(I)]
R1¼0.0360,
R1¼0.0468,
o
o
R2¼0.0973
R2¼0.1023
R1¼0.0291,
R1¼0.0399,
o
o
R2¼0.0718
R2¼0.0782
R1¼0.0559,
R1¼0.1017,
o
o
R2¼0.1153
R2¼0.1281

L.-Y. Xin et al. / Journal of Solid State Chemistry 184 (2011) 1387–1392
1389
Scheme 1. Coordination modes of PHDA observed in complexes 1–3.
Fig. 1. (a) Coordination environment of the dinuclear cadmium unit in 1. Symmetry codes: A, ꢀx, 1ꢀy, 1ꢀz; B, ꢀ1þx, 1þy, z; C, 1ꢀx, ꢀy, 1ꢀz. (b) The dinuclear
cadmium connected by BBP ligands to form a 1D double-stranded chain.
˚
modes within coordinated water molecules. No peak of com-
pound 1–3 in ꢂ1680–1700 cmꢀ1 demonstrates complete depro-
tonation of the H2PHDA after forming the coordination polymers.
Various coordination modes of PHDA ligand in 1–3 are shown in
Scheme 1.
binuclear unit with O–O distances from 2.752(4) to 2.839(4) A
(Fig. 1(b)). The detailed hydrogen bond parameters are listed in
Table S2. The adjacent 1D chains are stacked in a parallel fashion
and cohered together by the weak effect of van der Waals force
into the entire 3D supramolecular network of complex 1.
3.2. Structural description of [Cd(PHDA)(BPP)(H2O)]n (1)
3.3. Structural description of [Zn(PHDA)(BPP)]n (2)
Single-crystal X-ray analysis shows the asymmetric unit of
compound 1 contains two crystallographically independent mole-
cule fragments with almost uniform configuration (Fig. S1). So,
only one of molecule fragments is discussed below (Fig. 1(a)).
Each molecule fragment includes one crystallographically sepa-
rate Cd atom, one PHDA dianion, one BBP ligand, and one ligated
water molecule. The Cd atom displays a highly distorted penta-
gonal bipyramid with four oxygen atoms from two chelating
carboxylate group belonging to different PHDA molecules (Cd–O:
The asymmetric unit (Fig. 2a) of compound 2 contains one
crystallographically independent Zn(II) atom, one PHDA anion,
and one BPP molecule. The Zn(II) atom is coordinated by two
carboxylate oxygen atoms from two different PHDA ligand adopt-
ing a m1ꢀ :Z
Z1 0 (Scheme 1b) bridging coordination mode and two
nitrogen atom from two different BPP molecules to form a
distorted tetrahedral geometry. The Zn–O bond lengths are
˚
1.9511(15) and 1.9529(16) A, and Zn–N bond lengths are
˚
2.0324(18) and 2.0477(18) A.
˚
˚
2.323(3)A–2.600(3) A), two nitrogen atoms from BBP ligands
Along the crystallographic b axis, the PHDA ligands bridge the
Zn(II) centers to form zigzag carboxylate chains, which are
interconnected to each other through the BPP molecules to result
in a (4,4) grid layer (Fig. 2(b)). Each layer is corrugated with two
BPP ligands, two PHDA ligands, and four Zn atoms forming a
repeating rhombic grid with a side length of 12.3974\9.4542 A1
and a diagonal measurement of 17.6363\13.2332 A1 based on the
metal–metal distances. In order to minimize the presence of large
cavities and to stabilize the framework during the assembly
process, the corrugated nature and larger cavities for each layer
can permit two adjacent layers interpenetrate each other to
˚
˚
(Cd–N: 2.346(3) A and 2.369(3) A), and one ligated water
molecule (Cd–O: 2.351(2) A).
˚
The symmetry-related two cadmium atoms are connected by a
pair of PHDA anions via a m1ꢀ :
Z1 Z1 (Scheme 1a) coordination
mode to form a binuclear cadmium unit with the Cd y Cd
˚
distance of 5.3251 A. Extension of the structure through the two
pairs of bisymmetric BBP molecules results in a one-dimensional
double-stranded chain running along the [1 -1 0] crystal direc-
tion, as shown in Fig. 1(b). There exist H-bonds between ligated
water molecules and oxygen atoms in PHDA within each

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L.-Y. Xin et al. / Journal of Solid State Chemistry 184 (2011) 1387–1392
Fig. 2. (a) Coordination environment of the zinc unit in 2. Symmetry codes: A, ꢀx, ꢀ0.5þy, 0.5ꢀz; B, x, y, 0.5ꢀz. (b) The zinc clusters connected by PHDA and BPP ligands
to form a 2D (4, 4) grid. (c) The interpenetrated 2D layers. (d) Topology of 2 displaying 2D-2D interpenetration.
weave into a twofold interpenetrating structure (Fig. 2(c) and
Fig. S2), which may be attributed to the backbone flexibility of
PHDA and BPP ligands. Thus, the pronounced structural feature is
that 2 represents a 2D-2D interpenetrated network (Fig. 2(d)).
The adjacent interpenetrated networks are stacked in a parallel
fashion and cohered together by the weak effect of van der Waals
force to form the entire 3D supramolecular network of complex 2.
penetrating, that is, there are six-membered shortest circuits that
are penetrated by rods of the same net. A close-up network
perspective view of the self-penetration of the BPP linkers through
six-membered rings in the lattice is depicted in Fig. S3. The self-
assembly of the {Cu2(COO)4} paddle-wheel clusters in 3 can provide
the impetus for generation of the 6-connected 3-D lattice, with self-
penetration of the BPP ligands fostered by the tilted orientation of
the apical positions at the square pyramidal copper coordination
spheres.
3.4. Structural description of [Cu2(PHDA)2(BPP)]n(3)
The asymmetric unit of 3 contains one crystallographically
distinct Cu(II) atom, one PHDA anion and one half BPP molecule
(Fig. 3(a)). The Cu(II) center adopts a distorted square-pyramidal
coordination environment, in which four oxygen atoms from
carboxyl groups belonging to different PHDA anions occupy the
equatorial plane and one nitrogen atoms from BPP molecules
occupy the axial position. The Cu–O bond lengths are in the range
3.5. Fluorescent properties of 1 and 2
Inorganic–organic hybrid coordination polymers, especially
those with d10 metal centers, have been investigated for photo-
luminescent properties and for potential applications as fluores-
cence-emitting materials, such as light-emitting diodes (LEDS).
The solid-state fluorescence spectra of PHDA, 1, and 2 at room
temperature have been determined, as shown in Fig. 4. It is shown
that complex 1 has a maximum emission at 375 nm and 2
displays a strong emission at 376 nm. These emissions are
˚
˚
of 1.966(3)–1.979(3) A and the Cu–N bond lengths is 2.156(4) A.
The symmetry-related two Cu atoms are cohered together by
the carboxyl groups of PHDA anions by a m2ꢀ :
Z1 Z1 mode
(Scheme 1c) to form the {Cu2(COO)4} paddlewheel units with
assigned to the intraligand
p
ꢀ
pn fluorescence emission since
˚
the CuyCu distance of 2.6333(10) A, which are further connected
the corresponding PHDA ligand also shows a similar maximum
emission at 370 nm [50–53]. In addition, fluorescent spectra of 1
and 2 have more intensity at longer wavelength compared to free
PHDA ligand. Although more detailed theoretical and spectro-
scopic studies may be necessary for better understanding of the
luminescent mechanism [54,55], the strong fluorescence emis-
sions of those complexes make them potentially useful photo-
active materials.
through the full length of the PHDA ligands constructing [Cu(PH-
DA)]n carboxylate layer subunit that lies parallel to the ac crystal
plane (Fig. 3(b)). Within the layer, each {Cu2(COO)4} paddlewheel
unit is connected to four adjacent ones in a rhomboid grid (4,4)
manner. The parallel [Cu(PHDA)]n layer are pillared to each other
by gauche-anticonformation BPP tethers to build a [Cu2(PH-
DA)2(BPP)]n 3-D coordination polymer lattice (Fig. 3(c)).
Topologically, the Cu dimers can be regarded as the network
nodes. These are linked in two dimensions by the PHDA ligands, to
give (4,4) sheets, and in the third dimension by pairs of BPP ligands
acting as single bridges. For each cluster, one pair of BPP ligands
bridges to the sheet above, and another ones bridge to the sheet
below, making the Cu dimers six-connecting nodes. The BPP bridges,
however, are slanted rather than perpendicular to the sheets and
crisscross in two different directions (Fig. 3(e)). Thus, the usual R-Po
net is not formed, but rather an unusual six-connected net with
(48668) rob network topology is formed (Fig. 3(d)). This net is self-
4. Conclusions
We have presented the synthesis and structure of three new
coordination polymers assembled from H2PHDA with pendant
arms and flexible BPP molecule under hydrothermal conditions.
Their structures show a varieties of supramolecular networks
from 1D double-stranded chain, 2D-2D interpenetrated (4,4)
grid layer to 3D self-penetrated framework, showing a remarked

L.-Y. Xin et al. / Journal of Solid State Chemistry 184 (2011) 1387–1392
1391
Fig. 3. (a) Coordination environment of the dinuclear copper unit in 3. Symmetry codes: A, ꢀx, 1ꢀy, ꢀz; B, ꢀ0.5þx, 1ꢀy, 0.5ꢀz; C, 0.5ꢀx, y, ꢀ0.5þz. (b) The copper
clusters connected by PHDA to form a 2D layer. (c) Containing paddle-wheel layers connected by BPP to form 3D network. (d) 3D self-penetrating 6-connected (48. 66. 8)
network topology.
Acknowledgments
This work was supported by the National Natural Science
Foundation of China (Nos. 20971064 and 21071074) and the
Foundation of Education Committee of Henan Province (No.
092102210315).
Appendix A. Supporting information
Supplementary data associated with this article can be found
in the online version at doi:10.1016/j.jssc.2011.04.002.
References
[1] X. Zhu, J.W. Zhao, B.L. Li, Y. Song, Y.M. Zhang, Y. Zhang, Inorg. Chem. 49 (2010)
1266.
[2] L.F. Ma, L.Y. Wang, S.H. Chen, H.W. Hou, S.R. Batten, Polyhedron 28 (2009)
Fig. 4. Emission spectra of compound 1 and 2 compared to free PHDA ligands.
2494.
[3] J.L.C. Rowsell, O.M. Yaghi, J. Am. Chem. Soc. 128 (2006) 1304.
[4] T.L. Hu, R.Q. Zou, J.R. Li, X.H. Bu, Dalton Trans. (2008) 1302.
[5] M. Wang, M.H. Xie, C.D. Wu, Y.G. Wang, Chem. Commun. (2009) 2396.
[6] O.M. Yaghi, M. O’Keeffe, M. Kanatzidis, J. Solid State Chem. 152 (2000) 1.
[7] S. Noro, R. Kitaura, M. Kondo, S. Kitagawa, T. Ishii, H. Matsuzaka,
M. Yamashita, J. Am. Chem. Soc. 124 (2002) 2568.
[8] L. Carlucci, G. Ciani, D.M. Proserpio, Coord. Chem. Rev. 246 (2003) 247.
[9] L. Brammer, Chem. Soc. Rev. 33 (2004) 476.
[10] R. Matsuda, R. Kitaura, S. Kitagawa, Y. Kubota, R.V. Belosludov, T.C. Kobayashi,
H. Sakamoto, T. Chiba, M. Takata, Y. Kawazoe, Y. Mita, Nature 436 (2005) 238.
[11] X.G. Liu, J. Huang, S.S. Bao, Y.Z. Li, L.M. Zheng, Dalton Trans. (2009) 9837.
structure sensitivity to metal(II) center with different coordina-
tion geometries. It is found that the PH value and different solvent
of the reactive system play an important role to form the
crystalloid. Fluorescent analyses of 1 and 2 show the enhance-
ment of luminescence in the longer wavelength compared to that
of free PHDA ligand.

1392
L.-Y. Xin et al. / Journal of Solid State Chemistry 184 (2011) 1387–1392
[12] H. Ren, T.Y. Song, J.N. Xu, S.B. Jing, Y. Yu, P. Zhang, L.R. Zhang, Cryst. Growth
Des. 9 (2009) 105.
[13] M.H. Zeng, Y.L. Zhou, M.C. Wu, H.L. Sun, M. Du, Inorg. Chem. 49 (2010) 6436.
[14] P. Pachfule, T. Panda, C. Dey, R. Banerjee, CrystEngComm 12 (2010) 2381.
[15] M.A. Braverman, R.J. Staples, R.M. Supkowski, R.L. LaDuca, Ployhedron 27
(2008) 2291.
[34] M.A. Braverman, R.L. LaDuca, Cryst. Growth Des. 7 (2007) 2343.
[35] F.N. Dai, J.M. Dou, H.Y. He, X.L. Zhao, D.F. Sun, Inorg. Chem. 49 (2010) 4117.
[36] L. Pan, K.M. Adams, H.E. Hernandez, X. Wang, C. Zheng, Y. Hattori, K. Kaneko,
J. Am. Chem. Soc. 125 (2003) 3062.
[37] O. Fabelo, J. Pasan, L.C. Delgado, F.S. Delgado, F. Lloret, M. Julve, C.R. Perez,
Inorg. Chem. 48 (2009) 6086.
[16] P.J. Stang, B.A. Olenyuk, Chem. Res. 30 (1997) 502.
[17] Z. Ni, A Yassar, T. Antoun, O.M. Yaghi, J. Am. Chem. Soc. 127 (2005) 12752.
[18] H. Furukawa, J. Kim, K.E. Plass, O.M. Yaghi, J. Am. Chem. Soc. 128 (2006) 8398.
[19] B. Moulton, J. Lu, A. Mondal, M.J. Zaworotko, Chem. Commun. (2001) 863.
[20] F.M. Tabellion, S.R. Seidel, A.M. Arif, P.J. Stang, Angew. Chem. Int. Ed. 40
(2001) 1529.
[21] L. Pan, E.B. Woodlock, X. Wang, K.C. Lam, A.L. Rheingold, Chem. Commun.
(2001) 1762.
[22] M.L. Tong, Y.M. Wu, J. Ru, X.M. Chen, H.C. Chang, S. Kitagawa, Inorg. Chem. 41
(2002) 4846.
[23] W.J. Zhuang, X.J. Zheng, L.C. Li, D.Z. Liao, H. Ma, L.P. Jin, CrystEngComm 9
(2007) 653.
[24] Z.Z. Lin, F.L. Jiang, D.Q. Yuan, L. Chen, Y.F. Zhou, M.C. Hong, Eur. J. Inorg. Chem.
(2005) 1927.
[25] T.F. Liu, J. Lu¨, R. Cao, CrystEngComm 12 (2010) 660.
[26] K. Uemura, R. Matsuda, S. Kitagawa, J. Solid State Chem. 178 (2005) 2420.
[27] Z.H. Zhang, Z.L. Shen, T. Okamura, H.F. Zhu, W.Y. Sun, N. Ueyama, Cryst.
Growth Des. 5 (2005) 1191.
[28] H.F. Zhu, J. Fan, T. Okamura, Z.H. Zhang, G.X. Liu, K.B. Yu, W.Y. Sun,
N. Ueyama, Inorg. Chem. 45 (2006) 3941.
[38] T. Liu, J. Lu, L. Shi, Z. Guo, R. Cao, CrystEngComm 11 (2009) 583.
[39] A.D. Burrows, R.W. Harrington, M.F. Mahon, S.J. Teat, Eur. J. Inorg. Chem.
(2003) 766.
[40] S.Y. Yao, Y.Q. Tian, CrystEngComm 12 (2010) 697.
[41] P.K. Chen, Y. Qi, Y.X Che, J.M. Zheng, CrystEngComm 12 (2010) 720.
[42] J. Yang, J.F. Ma, S.R. Batten, Z.M. Su, Chem. Commun. (2008) 2233.
[43] X.D. Zheng, T.B. Lu, CrystEngComm 12 (2010) 324.
[44] L.K. Sposato, J.A. Nettleman, R.L. LaDuca, CrystEngComm 12 (2010) 2374.
[45] M. Zhang, D. Li, J. Wang, F. Fu, M. Du, K. Zou, X. Gao, Dalton Trans. (2009)
5355.
[46] GM Sheldrick, SHELXS-97, Program for X-ray Crystal Structure Determina-
tion, Go¨ttingen University, Germany, 1997.
[47] GM Sheldrick, SHELXL-97, Program for X-ray Crystal Structure Refinement,
Go¨ttingen University, Germany, 1997.
[48] GM Sheldrick, SHELXTL, Version V, Siemens Industrial Automation Inc,
Madison, Wisconsin, U.S.A, 1997.
[49] L.F. Ma, B. Liu, L.Y. Wang, C.P. Li, M. Du, Dalton Trans. 39 (2010) 2301.
[50] D.R. Xiao, R. Yuan, Y.Q. Chai, E.B. Wang, Eur. J. Inorg. Chem. (2008) 2610.
[51] J. Tao, M.L. Tong, J.X. Shi, X.M. Chen, S.W. Ng, Chem. Commun. (2000) 2043.
[52] L.F. Ma, B. Li, X.Y. Sun, L.Y. Wang, Y.T. Fan, Z. Anorg. Allg. Chem. 636 (2010)
1606.
[29] H.F. Zhu, W.Y. Sun, T. Okamura, N. Ueyama, Inorg. Chem. Commun. 6 (2003)
168.
[30] G.X. Liu, Y.Q. Huang, Q. Chu, T.A. Okamura, W.Y. Sun, H. Liang, N. Ueyama,
Cryst. Growth Des. 8 (2008) 3233.
[31] S. Zang, Y. Su, Y. Li, Z. Ni, Q. Meng, Inorg. Chem. 45 (2006) 174.
[32] L. Wang, M. Yang, G. Li, Z. Shi, S. Feng, Inorg. Chem. 45 (2006) 2474.
[33] S. Wang, Y. Hou, E. Wang, Y. Li, L. Xu, J. Peng, S. Liu, C. Hu, New J. Chem. 27
(2003) 1144.
[53] F.Y. Lian, F.L. Jiang, D.Q. Yuan, J.T. Chen, M.Y. Wu, M.C. Hong, CrystEngComm
10 (2008) 905.
´
[54] A.R. Dieguez, A.S. Castillo, A. Sironi, J.M. Seco, E. Colacio, CrystEngComm 12
(2010) 1876.
[55] H.Y. Bai, J.F. Ma, J. Yang, L.P. Zhang, J.C. Ma, Y.Y. Liu, Cryst. Growth Des. 10
(2010) 1946.