Three interpenetrated frameworks constructed by long flexible N,N′-bipyridyl and dicarboxylate ligands

Article abstract of DOI:10.1016/j.poly.2005.06.026

Three interpenetrated polymeric networks, {[Co(bpp)(OH-BDC)]·H ₂O}_n (1) [Ni(bpp)_1.5(H₂O)(OH-BDC)] _n (2) and {[Cd(bpp)(H₂O)(OH-BDC)]·2H ₂O}_n (3), have been prepared by hydrothermal reactions of 1,3-bis(4-pyridyl)propane (bpp), 5-hydroxyisophthalic acid (OH-H ₂BDC), with Co(NO₃)₂·6H₂O, Ni(NO₃)₂·6H₂O and Cd(NO ₃)₂·4H₂O, respectively. Single-crystal X-ray diffraction analyses reveal that the three compounds all exhibit interpenetrated but entirely different structures. Compound 1 is a fourfold interpenetrated adamantanoid structure with water molecules as space fillers, in which bpp adopts a TG conformation (T = trans, G = gauche). Compound 2 is an interdigitated structure from the interpenetrated long arms of one-dimensional molecular ladders, while bpp in 2 adopts both TT and TG conformations. Compound 3 is a twofold interpenetrated three-dimensional network from a one-dimensional metal-carboxylate chain bridged by TG conformational bpp. The hydrogen bonding interactions in 1-3 further stabilize the whole structural frameworks and play critical roles in their constructions.

Full text of DOI:10.1016/j.poly.2005.06.026

Polyhedron 24 (2005) 2955–2962
www.elsevier.com/locate/poly
Three interpenetrated frameworks constructed by long flexible
N,N0-bipyridyl and dicarboxylate ligands
*
Xiao-Ju Li, Rong Cao , Wen-Hua Bi, Yan-Qin Wang, Yu-Ling Wang, Xing Li
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences,
Yangqiao West Road 155, Fujian, Fuzhou 350002, China
Received 10 March 2005; accepted 9 June 2005
Available online 8 August 2005
Abstract
Three interpenetrated polymeric networks, {[Co(bpp)(OH-BDC)] Æ H2O}n (1) [Ni(bpp)1.5(H2O)(OH-BDC)]n (2) and {[Cd(bpp)-
(H2O)(OH-BDC)] Æ 2H2O}n (3), have been prepared by hydrothermal reactions of 1,3-bis(4-pyridyl)propane (bpp),
5-hydroxyisophthalic acid (OH-H2BDC), with Co(NO3)2 Æ 6H2O, Ni(NO3)2 Æ 6H2O and Cd(NO3)2 Æ 4H2O, respectively. Single-
crystal X-ray diffraction analyses reveal that the three compounds all exhibit interpenetrated but entirely different structures. Compound
1 is a fourfold interpenetrated adamantanoid structure with water molecules as space fillers, in which bpp adopts a TG conformation
(T = trans, G = gauche). Compound 2 is an interdigitated structure from the interpenetrated long arms of one-dimensional molec-
ular ladders, while bpp in 2 adopts both TT and TG conformations. Compound 3 is a twofold interpenetrated three-dimensional
network from a one-dimensional metal-carboxylate chain bridged by TG conformational bpp. The hydrogen bonding interactions
in 1–3 further stabilize the whole structural frameworks and play critical roles in their constructions.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Cobalt(II); Nickel(II); Cadmium(II); X-ray diffraction; Interpenetrated
1. Introduction
outstanding examples are the long dipyridyl ligands,
such as 1,2-bis(4-pyridyl)ethane (bpe) and 1,2-di(4-pyr-
idyl)ethylene (dpe). Using these ligands [11–17] or their
mixture with other organic ligands [18–20], many desir-
able interpenetrated metal-organic networks have been
constructed. However, the assembly of these neutral
N-donor ligands with metal ions is heavily dependent
on the presence of different counterions [21].
In this regard, our synthetic strategy was to select
an analogue of bpe or dpe: 1,3-bis(4-pyridyl)propane
(bpp), and introduce benzenedicarboxylic acid
(5-hydroxyisophthalic acid, OH-H2BDC) as an auxil-
iary ligand into the reaction systems, with the follow-
ing considerations: (1) Bpp, compared to bpe or
dpe, has a longer and more flexible conformation.
Accordingly, it possesses TT, TG, GG and GG0 con-
formations (T = trans, G = gauche) owing to the free
twist of the propyl group (–CH2–CH2–CH2–). Thereby
The rational design and construction of coordination
polymers based upon assembly of metal ions and multi-
functional organic ligands is an interesting research
field. This not only stems from their potential applica-
tion as functional materials but also from their intrigu-
ing structural topologies [1,2]. Among the various
architectures, interpenetrated and intertwinded phenom-
ena are frequently observed, especially in adamantanoid
networks, polythreaded and interdigitated structures [3–
7]. In principle, the exploration of long ligands usually
lead to large voids that may further result in interpene-
trated or entangled structures [8–10], of which the most
*
Corresponding author. Tel.: +86 591 83796710; fax: +86 591
83714946.
E-mail address: rcao@ms.fjirsm.ac.cn (R. Cao).
0277-5387/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.06.026

2956
X.-J. Li et al. / Polyhedron 24 (2005) 2955–2962
it can adopt different conformations to take part in
coordination [21–24]. (2) The aim of combining OH-
H2BDC into the reaction system is to simplify the
control and modulation of the final results, because
the deprotonated carboxylate groups, which possess
rich coordination modes (Scheme 1), may act as anio-
nic groups and afford neutral metal-organic frame-
works. (3) The hydroxyl group (–OH) can provide
hydrogen bonding interactions with other groups and
further stabilize the structures. On the other hand,
the architectures from mixed ligands of bpp and di-
or poly-carboxylate ligands, to our knowledge, are still
rare to date [20,25,26], although some metal-organic
frameworks from the direct assembly of bpp and me-
tal ions have been investigated [22–24]. Herein, we
wish to report the syntheses and characterizations of
three interpenetrated coordination polymers, {[Co(bpp)-
(OH-BDC)] Æ H2O}n (1), [Ni(bpp)1.5(H2O)(OH-BDC)]n
(2) and {[Cd(bpp)(H2O)(OH-BDC)] Æ 2H2O}n (3), assem-
bly from bpp, OH-H2BDC with CoII, NiII and CdII ions,
respectively. All of the three compounds display inter-
penetrated structures. Exo-bidentate bpp in 1 and 3
adopts a TG conformation, while bpp in 2 acts as a termi-
nal and exo-bidentate ligand with TT and TG conforma-
tions, respectively.
2. Experimental
2.1. Materials and physical measures
1,3-bis(4-pyridyl)propane and 5-hydroxyisophthalic
acid were purchased from Aldrich and used without
further purification, all the other reagents were com-
mercially available and used as purchased. Thermal
analyses were performed using a TGA/SDTA851
instrument with a heating rate of 15 ꢁC/min in a nitro-
gen stream. IR spectra as KBr disks were recorded on
a Magna 750 FT–IR spectrophotometer. Elementary
analyses were carried out by the elementary analysis
group of this institute on an Elementary Vario ELIII
analyzer.
2.2. Syntheses of the compounds
2.2.1. Preparation of {[Co(bpp)(OH-BDC)] Æ H2O}n
(1)
A mixture of Co(NO3)2 Æ 6H2O (0.058 g, 0.20 mmol),
5-hydroxyisophthalic acid (0.032 g, 0.20 mmol), 1,3-
bis(4-pyridyl)propane (0.040 g, 0.20 mmol) and NaOH
(0.016 g, 0.40 mmol) in distilled water (18 mL) was
sealed in a 25 mL stainless reactor with a Teflon liner
and heated to 165 ꢁC for 96 h. After cooling to room
temperature over 24 h, cube-shaped red crystals of 1
were obtained. Yield: 41%. Elementary Anal. Calc. for
C21H20CoN2O6 (455.32): C, 55.40; H, 4.43; N, 6.15.
Found: C, 55.38; H, 4.51; N, 6.11%. IR (KBr, cmꢀ1):
3400 (m), 2927 (w), 1615 (s), 1575 (vs), 1401 (vs), 1373
(s), 1276 (s), 1018 (m), 785 (s), 723 (s), 519 (m).
OH
O
M
O
M
2.2.2. Preparation of [Ni(bpp)1.5(H2O)(OH-BDC)]n
(2)
O
O
a
A mixture of Ni(NO3)2 Æ 6H2O (0.073 g, 0.25 mmol),
5-hydroxyisophthalic acid (0.045 g, 0.25 mmol), 1,3-
bis(4-pyridyl)propane (0.050 g, 0.25 mmol) and NaOH
(0.020 g, 0.50 mmol) in distilled water (18 mL) was
sealed in a 25 mL stainless reactor with a Teflon liner
and heated to 170 ꢁC for 96 h. After cooling to room
temperature over 24 h, block green crystals of 2 were ob-
tained. Yield: 64%. Elementary Anal. Calc. for C27.5H27-
NiN3O6 (554.23): C, 59.60; H, 4.91; N, 7.58. Found: C,
59.62; H, 5.02; N, 7.49%. IR (KBr, cmꢀ1): 3354 (w),
1616 (s), 1562 (vs), 1452 (s), 1412 (vs), 1357 (vs), 1277
(m), 1068 (m), 800 (s), 727 (s), 523 (m).
OH
O
O
M
M
O
O
b
OH
2.2.3. Preparation of {[Cd(bpp)(H2O)(OH-BDC)] Æ
2H2O}n (3)
A mixture of Cd(NO3)2 Æ 4H2O (0.077g, 0.25 mmol),
5-hydroxyisophthalic acid (0.045 g, 0.25 mmol), 1,3-
bis(4-pyridyl)propane (0.050 g, 0.25 mmol) and NaOH
(0.020 g, 0.50 mmol) in distilled water (18 mL) was
sealed in a 25 mL stainless reactor with a Teflon liner
and heated to 170 ꢁC for 96 h. After cooling to room
O
O
M
M
c
O
O
Scheme 1. The coordination modes of OH-BDC in compounds 1–3.

X.-J. Li et al. / Polyhedron 24 (2005) 2955–2962
2957
temperature over 24 h, block yellow crystals of 3 were
obtained. Yield: 45%. Elementary Anal. Calc. for
C21H24CdN2O8 (544.82): C, 46.30; H, 4.44; N, 5.14.
Found: C, 46.31; H, 4.39; N, 5.18%. IR (KBr, cmꢀ1):
3385 (w), 1616 (s), 1554 (vs), 1427 (s), 1377 (vs), 1277
(m), 1227 (m), 1016 (m), 978 (w), 779 (s), 737 (s), 575
(m).
tions each with an occupancy of 50%. Crystal data
and structure determination summaries for 1–3 are sum-
marized in Table 1, selected bonds and angles in Table 2.
3. Results and discussion
3.1. Syntheses and characterizations
2.2.4. X-ray crystallographic study
Measurement of 1 was conducted on a Rigaku Mer-
cury CCD diffractometer with graphite monochromated
Compounds 1–3 were synthesized through the hydro-
thermal reactions of bpp, OH-H2BDC with CoII, NiII
and CdII salts, respectively. Similar to the previous re-
ports by us and some other groups, the –OH group of
HO-H2BDC is not involved in coordination to the tran-
sition metal ions and only serves as a donor for hydro-
gen bonds to stabilize the structures of 1–3 (see
below), however, the –OH group as an electron-donating
group may influence the self-assembly process although
the reaction mechanism still remains unclear, because
the expected results were not obtained when using m-
isophthalic acid (H2BDC) instead of HO-H2BDC under
the same hydrothermal condition. The IR spectra of the
three compounds exhibit strong characteristic vibra-
tional bands of the carboxylate groups. For 1, the char-
acteristic bands of the carboxylate groups are shown at
1575 cmꢀ1 for the antisymmetric stretching band and
˚
Mo Ka radiation (k = 0.71073 A). Reflections (14335)
were collected at ꢀ100 ꢁC, of which 4327 reflections
were unique [27]. Intensity data for 2 and 3 were
measured on a Siemens Smart CCD diffractometer with
graphite-monochromated Mo Ka radiation (k =
˚
0.71073 A) at room temperature, the empirical absorp-
tion corrections were applied by using the SADABS pro-
gram [28]. The structures for 1–3 were solved by direct
methods [29] and refined on F2 by full-matrix least-
squares using the SHELXL-97 program package [30].
The positions of H atoms were generated geometrically
˚
(C–H bond fixed at 0.96 A), assigned isotropic thermal
parameters and allowed to ride on their parent carbon
atoms before the final cycle of refinement. For 2, the car-
bon atom (C15) is handled as disordered at two posi-
Table 1
Crystallographic data for compounds 1–3
1
2
3
Empirical formula
Formula weight
T (K)
C
455.32
173(2)
0.71073
21H20CoN2O6
C27.5H27N3NiO6
554.23
293(2)
C21H24CdN2O8
544.82
293(2)
˚
Wavelength (A)
0.71073
0.71073
Crystal system
Space group
monoclinic
P21/n
10.96(5)
10.90(3)
16.29(5)
103.806(14)
1891(11)
4
1.599
0.952
monoclinic
P21/n
10.1547(2)
17.8222(5)
14.2077(3)
91.89
2569.91(10)
4
1.432
monoclinic
C2/c
˚
a (A)
16.6695(11)
17.1742(11)
19.0262(12)
108.028(1)
5179.5(6)
8
1.397
0.886
2208
˚
b (A)
˚
c (A)
b (ꢁ)
3
˚
V (A )
Z
Dcalc (Mg mꢀ3
)
Absorption coefficient (mmꢀ1
F(000)
)
0.803
1156
940
Crystal size (mm)
h Range for data collection (ꢁ)
0.15 · 0.10 · 0.05
2.03–27.48
ꢀ14 6 h 6 14,
ꢀ14 6 k 6 14,
ꢀ21 6 l 6 14
14335
0.32 · 0.26 · 0.18
1.83–25.08
ꢀ12 6 h 6 11,
ꢀ10 6 k6 21,
ꢀ16 6 l 6 11
7633
0.48 · 0.28 · 0.20
3.15–25.02
ꢀ7 6 h 6 19,
ꢀ20 6 k 6 17,
ꢀ22 6 l 6 20
7460
Index ranges
Reflections collected
Refinement method
Data [I > 2r(I)]/parameters
Goodness-of-fit on F2
R1 indices (I > 2r(I))a
wR2 indices (I > 2r(I))b
full-matrix least-squares on F2
3447/279
1.131
full-matrix least-squares on F2
3937/347
1.115
full-matrix least-squares on F2
3295/298
1.325
0.0587
0.1704
0.922 and ꢀ0.452
0.0563
0.1131
0.651 and ꢀ0.641
0.0432
0.0980
0.296 and ꢀ0.299
ꢀ3
˚
Largest difference peak and hole (e A
)
P
P
a
R1 = iFoj ꢀ jFci/ jFoj.
P
P
2
2 1=2
b
wR2 ¼ ½ wðF 2o ꢀ F c2Þ = wðF 2oÞ ꢁ
.

2958
X.-J. Li et al. / Polyhedron 24 (2005) 2955–2962
(1562 cmꢀ1) and two symmetric stretching bands (1412
and 1357 cmꢀ1) are exhibited, the D values are 150
and 205 cmꢀ1, respectively. For 3, the typical antisym-
metric and symmetric stretching bands of carboxylate
groups are at 1564 and 1387 cmꢀ1, with a D value ca.
177 cmꢀ1. The results are consistent with the different
coordination modes of the carboxylate groups in the
three compounds, one coordination mode in 1 and 3,
two coordination modes in 2 (Scheme 1) [31].
To study the stability of the three compounds, ther-
mogravimetric analyses (TGA) were performed on poly-
crystalline samples in nitrogen atmosphere. For 1, the
weight loss of 4.08% from 160 to 279 ꢁC is equivalent
to the loss of one free water molecule per formula unit
(ca. 3.96%), indicating the presence of hydrogen bond-
ing interactions. After 317 ꢁC, the decomposition of
the framework starts. For 2, the thermogravimetric
analysis shows that there is no weight loss up to
360 ꢁC, where the entirely decomposition of 2 starts.
For 3, the weight loss of 6.78% (calculated: 6.61%) from
45 to 134 ꢁC, is attributed to the loss of two free water
molecules per formula unit. Complete decomposition
of the framework starts after 415 ꢁC.
Table 2
˚
Selected bond lengths (A) and angles (ꢁ) of compounds 1–3
Compound 1
Co–O(1)
1.986(4)
1.978(6)
2.047(4)
2.048(9)
Co–O(3B)
Co–N(2A)
Co–N(1)
O(3B)–Co–O(1)
O(3B)–Co–N(2A)
O(1)–Co–N(2A)
O(3B)–Co–N(1)
O(1)–Co–N(1)
100.2(2)
118.0(2)
110.8(2)
112.1(3)
100.0(2)
113.3(1)
N(2A)–Co–N(1)
Compound 2
Ni–O(1)
Ni–O(4B)
Ni–N(1)
Ni–O(2)
Ni–OW
2.139(2)
2.033(2)
2.103(3)
2.115(2)
2.066(2)
2.105(3)
Ni–N(2)
O(4B)–Ni–OW
O(4B)–Ni–N(1)
OW–Ni–N(1)
O(4B)–Ni–N(2)
OW–Ni–N(2)
N(1)–Ni–N(2)
O(4B)–Ni–O(2)
OW–Ni–O(2)
N(1)–Ni–O(2)
N(2)–Ni–O(2)
O(4B)–Ni–O(1)
OW–Ni–O(1)
N(1)–Ni–O(1)
N(2)–Ni–O(1)
O(2)–Ni–O(1)
94.1(8)
91.4(9)
93.7(1)
87.6(9)
88.6(9)
177.6(1)
162.8(8)
102.4(8)
92.4(9)
87.9(9)
100.9(8)
163.5(8)
92.7(9)
85.4(9)
62.2(7)
3.1.1. Crystal structure of compound 1
Single-crystal X-ray diffraction analysis reveals that 1
is a fourfold interpenetrated adamantanoid structure. As
shown in Fig. 1, each CoII center is in a distorted tetra-
hedral geometry, which is seldom displayed in cobalt-
carboxylate compounds [32]. Two nitrogen atoms from
different bpp ligands and two monodentate carboxylate
oxygen atoms from different OH-BDC ligands coordinate
to the metal center. The average distances of Co–N and
Compound 3
Cd–O(4A)
Cd–N(2B)
Cd–N(1)
2.284(5)
2.324(6)
2.341(5)
2.355(5)
2.379(6)
2.516(5)
2.614(5)
Cd–O(1)
Cd–OW1
Cd–O(2)
˚
Co–O are 1.986(4) and 2.048(1) A, respectively. OH-
Cd–O(3A)
BDC acts as a bis-monodentate ligand to link the CoII
centers (Scheme 1(a)). The hydroxyl group (–OH) does
not take part in coordination, but it is involved in a
O(4A)–Cd–N(2B)
O(4A)–Cd–N(1)
N(2B)–Cd–N(1)
O(4A)–Cd–O(1)
N(2B)–Cd–O(1)
N(1)–Cd–O(1)
86.4(2)
98.1(2)
96.4(2)
135.5(2)
138.0(2)
83.1(2)
84.8(2)
95.0(2)
168.5(2)
87.0(2)
163.3(2)
85.4(2)
97.2(2)
53.4(2)
81.5(2)
52.1(2)
137.6(2)
83.7(2)
84.2(2)
89.4(2)
136.8(2)
O(4A)–Cd–OW1
N(2B)–Cd–OW1
N(1)–Cd–OW1
O(1)–Cd–OW1
O(4A)–Cd–O(2)
N(2B)–Cd–O(2)
N(1)–Cd–O(2)
O(1)–Cd–O(2)
OW1–Cd–O(2)
O(4A)–Cd–O(3A)
N(2B)–Cd–O(3A)
N(1)–Cd–O(3A)
O(1)–Cd–O(3A)
OW1–Cd–O(3A)
O(2)–Cd–O(3A)
Symmetry code: for 1 (A) x + 1/2, ꢀy + 5/2, z ꢀ 1/2; (B) x + 1/2, ꢀy + 3/2,
z + 1/2. 2 (B) x + 1, y, z. 3 (A) x, ꢀy + 1, z ꢀ 1/2; (B) x ꢀ 1/2, y + 1/2, z.
1401 cmꢀ1 for the symmetric stretching band. The sepa-
Fig. 1. ORTEP drawing of the coordination environment around CoII
in 1 with the thermal ellipsoids at the 30% probability level.
ration (D) between
masym(CO2) and msym(CO2) is
174 cmꢀ1. For 2, one antisymmetric stretching band

X.-J. Li et al. / Polyhedron 24 (2005) 2955–2962
2959
strong hydrogen bonding interaction with a free water
˚
molecule (O5–Hꢂ ꢂ ꢂOW, 2.692 A), which is consistent
with the result of the TGA. Bpp in a TG conformation
bridges the CoII centers, the dihedral angle between the
two pyridine rings is 80.6ꢁ. Thus, ten CoII centers are
connected by twelve bridging ligands, namely six bpp
and six OH-BDC, generating a adamantanoid cage,
which is further extended into a three-dimensional struc-
ture (Fig. 2). The separations of the adjacent Coꢂ ꢂ ꢂCo
atoms bridged by bpp and OH–BDC are 12.657 and
˚
9.711 A, respectively. The long spacers between coordi-
nation sites result in large cavities within the adamanta-
noid cages. In order to minimize the big void cavities and
stabilize the framework by nature, the potential voids
are effectively filled via mutual interpenetration of three
Fig. 3. Perspective view of the fourfold interpenetrated adamantanoid
network in 1 with bridging ligands and water molecules omitted for
clarity.
independent equivalent frameworks, generating
a
fourfold interpenetrated adamantanoid architecture
(Fig. 3). Free water molecules are accommodated inside
the framework and further shrink the void spaces. An-
other isomorphous complex, {[Zn(bpp)(OH-BDC)]
(H2O)}n, has been obtained and published by us in
another report [26].
3.1.2. Crystal structure of compound 2
Compound 2 is a polythreaded structure constructed
through interpenetration of long arms of neutral one-
dimensional molecular ladders. As shown in Fig. 4, each
NiII center is in a highly distorted octahedral coordina-
tion geometry. Four oxygen atoms from one water mol-
Fig. 4. ORTEP drawing of the coordination environment around NiII
in 2 with the thermal ellipsoids at the 30% probability level.
ecule, one mono- and one chelating carboxylate groups
of different OH-BDC ligands comprise the equatorial
plane. Two nitrogen atoms from different conforma-
tional bpp ligands occupy the axial positions with the
N1–Ni–N2 bond angle being 177.6(1)ꢁ. The deviation
of the NiII center from the O4 equatorial mean plane
of the octahedron toward the apical nitrogen atom is
˚
0.232 A. The Ni–N and Ni–O bond distances are all
within the normal ranges. OH-BDC behaves as a bridge
through its mono- and chelating carboxylate groups to
link different metal centers (Scheme 1(b)). Likewise,
the hydroxyl group (–OH) does not participate in
coordination, it is involved in a hydrogen bonding
interaction with the coordinated water molecule
Fig. 2. (a) View of a single adamantanoid cage. (b) Perspective view of
the three-dimensional adamantanoid structure in 1. For clarity only the
CoII centers are shown, with the bonds representing the bridging
ligands.
i
˚
[OW–Hꢂ ꢂ ꢂO5 2.803 A, (i) x + 1/2, ꢀy + 1/2, z + 1/2].

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X.-J. Li et al. / Polyhedron 24 (2005) 2955–2962
The most interesting feature of this structure is that
there are two types of conformational bpp ligands with
different coordination modes [22]. One with the two pyr-
idyl rings being parallel adopts a TG conformation
through bridging two NiII centers. The other possesses
a TT conformation and serves as a terminal ligand,
the dihedral angle between the two pyridyl rings is
79.6ꢁ. As shown in Fig. 5, the TG conformational bpp
ligand and OH-BDC engage neighboring NiII centers
into a one-dimensional neutral molecular ladder con-
taining [Ni4(bpp)2(OH-BDC)2] rectangles (14.023 ·
2
˚
10.155 A ). The TT conformational bpp ligand behaves
as a lateral arm of the ladder through its one pyridyl
ring coordinating to a NiII center, which prevents the
formation of an extended motif. It is noteworthy that
due to the absence of large solvent or guest molecules
to fill the void space in the molecular ladder during
assembly process, the terminal TT conformational bpp
as long arms are threaded into [Ni4(bpp)2(OH-BDC)2]
rectangles of an adjacent molecular ladder. Each rectan-
gle is oppositely penetrated by two lateral arms from dif-
ferent molecular ladders, but there are no pꢂ ꢂ ꢂp
interactions between the two mutual parallel and stagger
pyridyl rings (Fig. 6). Such penetration not only effec-
tively fills into the void space of the rectangles, but also
results in a polythreaded polymeric structure. The
hydrogen bonding interactions between coordinated
water molecules and uncoordinated carboxylate oxygen
Fig. 6. Perspective view of the polythreaded polymeric structure in 2,
with the bonds representing OH-BDC and exo-bidentate bpp.
groups of OH-BDC further stabilize the whole struc-
tural framework. Although some polythreaded architec-
tures from molecular ladders with both inner rungs and
lateral arms have been reported [33–35], the structural
motif constructed by bpp with different conformations
and a dicarboxylate ligand is still unprecedented.
3.1.3. Crystal structure of compound 3
Compound 3 is a twofold interpenetrated three-
dimensional framework with free water molecules as
space fillers. As shown in Fig. 7, each CdII center is in
a distorted pentagonal bipyramidal geometry. Two che-
lating carboxylate groups from different OH-BDC li-
gands and one pyridyl nitrogen atom from a bpp
ligand comprise the equatorial basal plane, one water
molecule and one pyridyl nitrogen atom from the other
bpp ligand occupy the apical sites [OW1–Cd–N1
atoms of OH-BDC [OW–Hꢂ ꢂ ꢂO3ii 2.589 A; symmetry
˚
code: (ii) x + 1, y, z] as well as the above-mentioned be-
tween the coordinated water molecules and hydroxyl
168.5(2)ꢁ]. The CdII center is displaced about 0.221 A
˚
Fig. 5. Space-filling representation of
molecular ladder with long arms.
a
one-dimensional neutral
Fig. 7. ORTEP drawing of the coordination environment around CdII
in 3 with the thermal ellipsoids at the 30% probability level.

X.-J. Li et al. / Polyhedron 24 (2005) 2955–2962
2961
from the equatorial plane towards the axial donor atom.
The Cd–O and Cd–N bond distances are in the range
˚
˚
2.284(5)–2.614(5) A and 2.324(6)–2.341(5) A, respec-
tively. Different from 1 and 2, OH-BDC acts as a chelat-
ing bis-bidentate ligand (Scheme 1(c)) and bridges
different CdII centers to give rise to a one-dimensional
metal-carboxylate chain (Fig. 8). Exo-bidentate bpp
adopts a TG conformation with the dihedral angle be-
tween two pyridyl rings being 79.4ꢁ, which is similar to
that in 1. Thus bpp links the adjacent one-dimensional
chain into a three-dimensional framework with large
channels (Fig. 9). The Cdꢂ ꢂ ꢂCd distances bridged by
˚
bpp and OH-BDC are 11.967 and 10.117 A, respec-
tively. In order to shrink the void space and stabilize
the final product, the three-dimensional network is inter-
penetrated into itself to generate an interwining network
(Fig. 10). Free water molecules are accommodated in the
residual empties and further stabilize the structural
framework through extensive hydrogen bonding interac-
tions between coordinated water molecules and carbox-
ylate oxygen atoms of OH-BDC [OW1–Hꢂ ꢂ ꢂO1i
˚
2.679 A, (i) ꢀx + 1, ꢀy + 1, ꢀz + 1], between coordi-
Fig. 10. Perspective view of the twofold interpenetrated three-dimen-
sional network with free water molecules along the c-axis in 3.
nated water molecules and free water molecules
ii
˚
[OW1–Hꢂ ꢂ ꢂOW3 2.856 A, (ii) ꢀx + 1, y, ꢀz + 3/2], be-
tween free water molecules and carboxylate oxygen
ii
˚
atoms of OH-BDC [OW2–H ꢂ ꢂ ꢂ O2 2.900 A], between
Fig. 8. View of a one-dimensional metal-carboxylate chain.
free water molecules and free water molecules [OW4–
˚
Hꢂ ꢂ ꢂOW5 2.116 A], as well as between hydroxyl groups
of OH-BDC and free water molecules [O5–Hꢂ ꢂ ꢂOW5
˚
2.700 A].
4. Conclusions
The hydrothermal reactions of 1,3-bis(4-pyridyl)pro-
pane (bpp), 5-hydroxyisophthalic acid (OH-H2BDC)
and different metal salts produced three interpene-
trated or polythreaded coordination polymers. The
long flexible bpp adopts different conformations to
link the metal ions. Owing to the existence of large
voids from long metal–metal distances bridged by
bpp and OH-BDC, all of the three compounds exhibit
interpenetrated structures. This research also demon-
strated that the presence of anionic groups (carboxyl-
ate groups) can simplify the design and construction
of the compounds.
5. Supplementary data
Crystallographic data (excluding structure factors)
for the structures in this paper have been deposited
in the Cambridge Crystallographic Data Center as
Fig. 9. Perspective view of the three-dimensional network possessing
large channels along the c-axis in 3.

2962
X.-J. Li et al. / Polyhedron 24 (2005) 2955–2962
[14] J.M. Knaust, S. Lopez, S.W. Keller, Inorg. Chim. Acta 324 (2002)
81.
[15] L. Carlucci, G. Ciani, D.M. Proserpio, S. Rizzato, Chem.
Commun. (2000) 1319.
[16] C.V. Krishnamohan Sharma, R.D. Rogers, Chem. Commun.
(1999) 83.
[17] M. John Plater, M.R.S.J. Foreman, R.A. Howie, J.M.S. Skakle,
Inorg. Chim. Acta 318 (2000) 175.
supplementary publication, CCDC Nos. 240643–240645
for complexes 1–3, respectively. Copies of the data can
be obtained free of charge on application to CCDC,
12 Union Road, Cambridge CB2 1EZ, UK (fax: (inter-
net) +44 1223 336 033; e-mail: deposit@ccdc.cam.ac.uk).
or www at http://www.ccdc.cam.ac.uk].
`
[18] V. Niel, M.C. Muooz, A.B. Gaspar, A. Galet, G. Levchenko,
J.A. Real, Chem. Eur. J. 8 (2002) 2446.
Acknowledgements
[19] J.Y. Lu, A.M. Babb, Inorg. Chem. 40 (2001) 3261.
[20] J. Luo, M. Hong, R. Wang, R. Cao, L. Han, Z. Lin, Eur. J.
Inorg. Chem. (2003) 2705.
[21] S.R. Batten, J.C. Jeffery, M.D. Ward, Inorg. Chim. Acta 292
(1999) 231.
[22] M.V. Marinho, M.I. Yoshida, K.J. Guedes, K. Krambrock, A.J.
Bortoluzzi, M. Ho¨rner, F.C. Machado, W.M. Teles, Inorg. Chem.
43 (2004) 1539.
The authors thank the financial support from the Na-
tional Natural Science Foundation of China (90206040,
20325106, 20333070), the Natural Science Foundation
of Fujian Province (B982003), and the ‘‘One-hundred
Talent’’ Project from CAS.
[23] L. Carlucci, G. Ciani, M. Moret, D.M. Proserpio, S. Rizzato,
Angew. Chem. Int. Ed. 39 (2000) 1506.
[24] M.J. Plater, M.R.S.J. Foreman, T. Gelbrich, M.B. Hursthouse, J.
Chem. Soc., Dalton Trans. (2000) 1995.
References
[1] R. Robson, B.F. Abrahams, S.R. Batten, R.W. Gable, B.F.
Hoskins, J. Liu, Supramolecular Architecture, American Chem-
ical Society, Washington, DC, 1992, p. 256.
[2] M. Moulton, L.P. Wu, T. Kuroda-Sowa, Adv. Inorg. Chem. 46
(1999) 173.
[3] M.J. Zaworotko, Chem. Soc. Rev. (1994) 283.
[4] O.R. Evans, W.B. Lin, Acc. Chem. Res. 35 (2002) 511.
[5] K. Biradha, M. Fujita, Chem. Commun. (2002) 1866.
[6] M. Kondo, T. Joshitomi, K. Seki, H. Matsuzaka, S. Kitagawa,
Angew. Chem. Int. Ed. Engl. 36 (1997) 1844.
[25] Z.Y. Fu, S.M. Hu, J.C. Dai, J.J. Zhang, X.T. Wu, Eur. J. Inorg.
Chem. (2003) 2670.
[26] X.J. Li, R. Cao, D.F. Sun, W.H. Bi, Y.Q. Wang, X. Li, M.C.
Hong, Cryst. Growth Des. 4 (2004) 775.
[27] Crystalclear: ver 1.36; Molecular Structure Corporation; Rigaku,
MSC/SSI, 491, South Orem Blvd, Orem, UT84058, 2001.
[28] G.M. Sheldrick, SADABS, Program for Empirical Absorption
Correction of Area Detector Data, University of Go¨ttingen,
Go¨ttingen, 1996.
[29] G.M. Sheldrick, SHELXS 97, Program for Crystal Structure
Solution, University of Go¨ttingen, Go¨ttingen, 1997.
[30] G.M. Sheldrick, SHELXS 97, Program for Crystal Structure
[7] K.N. Power, T.L. Hennigar, M.J. Zaworotko, New J. Chem.
(1998) 177.
[8] S.R. Batten, R. Robson, Angew. Chem. Int. Ed. 37 (1998)
1460.
[9] X.L. Wang, C. Qin, E.B. Wang, L. Xu, Z.M. Su, C.W. Hu,
Angew. Chem. Int. Ed. 43 (2004) 5036.
¨ ¨
Refinement, University of Gottingen, Gottingen, 1997.
[31] H.X. Zhang, B.S. Kang, A.W. Xu, Z.N. Chen, Z.Y. Zhou,
A.S.C. Chan, K.B. Yu, C. Ren, J. Chem. Soc., Dalton Trans.
(2001) 2559.
[10] F.A. Almeida Paz, Y.Z. Khimyak, A.D. Bond, J. Rocha, J.
Klinowski, Eur. J. Inorg. Chem. (2002) 2823.
[11] A.J. Blake, N.R. Champness, S.S.M. Chung, W.S. Li, M.
Schro¨der, Chem. Commun. (1997) 1005.
[12] D. Hagrman, R.P. Hammond, R. Haushalter, J. Zubieta, Chem.
Mater. 10 (1998) 2091.
[32] E. Lee, Y. Kim, D.Y. Jung, Inorg. Chem. 41 (2002) 501.
[33] M.L. Tong, H.J. Chen, X.M. Chen, Inorg. Chem. 39 (2000)
2235.
[34] M.A. Withersby, A.J. Blake, N.R. Champness, P. Hubbers-
tey, W.S. Li, M. Schro¨der, Angew. Chem. Int. Ed. 36
(1997) 2627.
[13] S.R. Batten, A.R. Harris, P. Jensen, K.S. Murray, A. Ziebell, J.
Chem. Soc., Dalton Tran. (2000) 3829.
[35] O.S. Jung, S.H. Park, K.M. Kim, H.G. Jang, Inorg. Chem. 37
(1998) 5781.