Temperature, cooling rate, and additive-controlled supramolecular isomerism in four Pb(II) coordination polymers with an in situ ligand transformation reaction

Article abstract of DOI:10.1021/cg300900m

Solvothermal reactions of Pb(Ac)₂ with a new flexible 1,3-bis(4-pyridyl-3-cyano)propane (1, BPCP) ligand under different synthesis conditions via an in situ ligand transformation reaction produced three true coordination polymorphs, namely, [PbL^2-]_n (for 2 and 3) and [Pb₃L^2-₃]_n (4), as well as their polymorphic framework [(Pb₂L^2-)·2H ₂O]_n (5) (H₂L = 1,3-bis(4-pyridyl-3-carboxyl) propane). These compounds were characterized by elemental analysis, IR, TG, PXRD, and single-crystal X-ray diffraction. In these compounds, the L ^2-ligand exhibits different coordination conformations and modes tuned by different synthesis conditions, including reaction temperature, cooling rate, and additive, and constructs various architectures by bridging a variety of building units. Polymorphs 2 and 3 display a 3D framework with 1D channels built up from dinuclear ringlike [Pb₂L^2-₂] units and dinuclear semi-ring-like [Pb₂L^2-] units, respectively. Polymorph 4 also features a 3D architecture constructed from dinuclear ringlike [Pb₂L^2-₂] units interlinked by the L^2- ligand. Interestingly, the framework of 4 is big enough to allow the other net to penetrate to form a 2-fold interpenetrating framework with a trinodal (3,6,10)-connected topology with a point symbol of (4 ³)(4⁴·6¹⁰·8)(4 ⁸·6²⁴·8⁹·10⁴). For 5, there exists two kinds of dinuclear ringlike [Pb₂L ^2-₂] units. These [Pb₂L^2- ₂] units are interconnected by Pb atoms to afford a 2D undulant network that is further connected by the hydrogen-bonding interactions and weak interactions to afford a 3D supramolecular network. In addition, the photoluminescence properties of 1-5 and the H₂L ligand in the solid state at room temperature were also investigated.

Full text of DOI:10.1021/cg300900m

Article
pubs.acs.org/crystal
Temperature, Cooling Rate, and Additive-Controlled Supramolecular
Isomerism in Four Pb(II) Coordination Polymers with an in Situ
Ligand Transformation Reaction
Dongsheng Deng,† Leilei Liu,§ Bao-Ming Ji,*,† Guojie Yin,†,‡ and Chenxia Du*,‡
†College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang 471022, People's Republic of China
‡Department of Chemistry, Zhengzhou University, Zhengzhou 450052, People's Republic of China
§College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang 455000, People's Republic of China
S
* Supporting Information
ABSTRACT: Solvothermal reactions of Pb(Ac)2 with a new
flexible 1,3-bis(4-pyridyl-3-cyano)propane (1, BPCP) ligand
under different synthesis conditions via an in situ ligand
transformation reaction produced three true coordination
polymorphs, namely, [PbL2−]n (for 2 and 3) and [Pb3L2−
]
3 n
(4), as well as their polymorphic framework
[(Pb2L2−)·2H2O]n (5) (H2L = 1,3-bis(4-pyridyl-3-carboxyl)-
propane). These compounds were characterized by elemental
analysis, IR, TG, PXRD, and single-crystal X-ray diffraction. In
these compounds, the L2−ligand exhibits different coordination
conformations and modes tuned by different synthesis conditions, including reaction temperature, cooling rate, and additive, and
constructs various architectures by bridging a variety of building units. Polymorphs 2 and 3 display a 3D framework with 1D
channels built up from dinuclear ringlike [Pb2L2−2] units and dinuclear semi-ring-like [Pb2L2−] units, respectively. Polymorph 4
also features a 3D architecture constructed from dinuclear ringlike [Pb2L2−2] units interlinked by the L2− ligand. Interestingly, the
framework of 4 is big enough to allow the other net to penetrate to form a 2-fold interpenetrating framework with a trinodal
(3,6,10)-connected topology with a point symbol of (43)(44·610·8)(48·624·89·104). For 5, there exists two kinds of dinuclear
ringlike [Pb2L2−2] units. These [Pb2L2−2] units are interconnected by Pb atoms to afford a 2D undulant network that is further
connected by the hydrogen-bonding interactions and weak interactions to afford a 3D supramolecular network. In addition, the
photoluminescence properties of 1−5 and the H2L ligand in the solid state at room temperature were also investigated.
synthetic pathways are required for the rational design of
supramolecular isomers with unique structures and properties,
and it is generally difficult to structurally predict for complexes
produced by new components.5 In comparison to supra-
molecular isomers with different chemical compositions due to
the coexistence of guest components,1c,6 polymorphs with a
fixed stoichiometry for all components are particularly rare for
coordination polymers (CPs),7 although it is widely observed
for organic compounds.8
Currently, the self-assembly of coordination polymers
depends on many factors, such as the nature of the metal
ion,9 structural features of the organic ligand,10 counterion,11
and a number of experimental variables containing reaction
temperature, reagent ratio, pH value, solvent system, and the
methods of the crystallization.12 Most research results suggest
that a subtle alteration by means of these factors can lead to
totally different products.13 In this regard, reaction temperature
has been verified as a crucial parameter in influencing the
INTRODUCTION
■
Supramolecular isomerism, as coined by Zaworotko, is used to
describe the existence of more than one type of network
superstructure for a given set of components.1 In some
instances, supramolecular isomerism can be synonymous with
polymorphism that is an intriguing phenomenon in crystal
engineering. However, in other situations, supramolecular
isomers are not true polymorphs for their different chemical
compositions caused by the coexistence of different guest
molecules.1d In this context, the term polymorphic frameworks
was defined by Matzger to better describe these different
architectures or superstructures with the existence of guest or
solvent molecules.2 Because of the dissimilarity in crystal
structures, supramolecular isomers (including polymorphs and
polymorphic frameworks) can vary significantly in their
physicochemical properties. An understanding of the relation-
ship between the structure and property in supramolecular
isomers is particularly important as epitomized by the fast
growing number of crystal structures in the Cambridge
Structural Database (CSD)3 as well as the rapidly expanding
scope of attention and a great many research reports on
supramolecular isomers.4 However, methods of controlling the
Received: July 12, 2012
Revised: September 28, 2012
Published: October 10, 2012
© 2012 American Chemical Society
5338
dx.doi.org/10.1021/cg300900m | Cryst. Growth Des. 2012, 12, 5338−5348

Crystal Growth & Design
Article
Scheme 1. Synthetic Route of H2L Ligand
Scheme 2. Possible Conformations of H2L Ligand
formation of CPs with variable topologies based upon the
conformations of ligands.14 It is well-known that flexible
organic linkers inherently hold the potential of adopting
different conformations under different conditions, especially at
different temperatures.15 The thermodynamically favored
conformer associated with a large activation barrier can be
achieved at high temperature, whereas low temperature favors
the kinetic conformer because the thermal energy relies on the
temperature proportionally. Therefore, the thermodynamically
or kinetically favored conformers could be obtained by carefully
controlling the reaction temperature.14,16 Accordingly, it is
expected that the reaction temperature should play an
additional crucial factor in determining the CP topology and
the dimensionality of the structures through controlling the
ligand conformation.
On the other hand, most of the research on CPs so far has
focused on d-block transition CPs, and p-block main CPs have
been relatively less explored. Compared with the transition-
metal atoms, the main group metal lead atom, with a larger
radius and [Xe]4f125d106s26p2 electronic configurations, can
give the Pb(II) cation variable coordination numbers (from 2
to 10), which provide unique opportunities for the construction
of novel network topologies and some fascinating physical
properties.17 Thus, lead-based structural chemistry has recently
been receiving increasing attention due to its fantastic
architectures and good physical properties.
supramolecular isomerism or polymorphism, similar to that
observed in the previous reports.6 (2) The H2L ligand has a
relatively longer spacer, and the two pyridyl groups can rotate
along its C−C bonds to form six configurations (Scheme 2).
Thereby, we anticipated that the conformational changes of the
H2L ligand could be controlled by regulating solvothermal
reaction conditions, which maybe lead to the generation of
various coordination polymers with different topological
structures. Fortunately, the foregoing effort has led to the
isolation of three true polymorphs, [PbL2−]n (for 2 and 3),
[Pb3L2−
]
(4), and their polymorphic frameworks
3
n
[(Pb2L2−2)·2H2O]n (5), with entirely distinct topological
networks by the assembly of Pb(II) acetate with the H2phda
ligand under different solvothermal reaction conditions,
including different temperatures, reaction components, and
crystallization conditions. Herein, we will present the in situ
syntheses, crystal structures, and thermal and photolumines-
cenct properties of compounds 1−5.
EXPERIMENTAL SECTION
■
General Procedure. 1,3-Bis(4-pyridyl)propane-N,N′-dioxide was
prepared according to the literature methods.18 All chemicals and
reagents were obtained from commercial sources and used as received.
The IR spectra were recorded on a Nicolet 6700 FT-IR spectrometer
in the 4000−400 cm−1 region. Elemental analyses for C, H, and N
were carried out on a Flash 2000 elemental analyzer. Powder X-ray
diffraction (PXRD) measurements were performed on a Bruker D8-
ADVANCE X-ray diffractometer with Cu Kα (λ = 1.5418 Å).
Luminescent spectra were recorded with a Rigaku RIX 2000
fluorescence spectrophotometer. Thermogravimetric analyses were
carried out on a SDT Q600 thermogravimetric analyzer. A platinum
pan was used for heating the sample with a heating rate of 10 °C/min
under a N2 atmosphere.
In the light of the above-mentioned motivations, we are
focusing our attention on using a novel 1,3-di(4-pyridyl-3-
cyano)propane ligand (BPCP, Scheme 1), as the flexible ligand
to construct CPs, which is based mostly on the following
considerations: (1) Two cyano groups of BPCP could be easily
hydrolyzed to carboxylic groups through an in situ ligand
transformation reaction under solvothermal conditions, and the
resulting flexible dicarboxylate linker (H2L = 1,3-di(4-pyridyl-3-
carboxyl)propane) shows a much greater thermal stability.
Therefore, this lignand has the ability to provide insight into
Preparation of 1,3-bis(4-pyridyl-3-cyano)propane (BPCP, 1).
To a solution of 1,3-bis(4-pyridyl)propane-N,N′-dioxide (4.61 g, 20
mmol) in CH2Cl2 (280 mL) was added 26.67 mL of Me3SiCN (200
mmol) with stirring at 0 °C. After stirring for 2 h, 9.28 mL of benzoyl
5339
dx.doi.org/10.1021/cg300900m | Cryst. Growth Des. 2012, 12, 5338−5348

Crystal Growth & Design
Article
Table 1. Summary of Crystallographic Data for 1−5
1
2
3
4
5
empirical formula
fw
C15H12N4
248.29
C15H12N2O4Pb
491.47
C15H12N2O4Pb
491.46
C45H36N6O12Pb3
1474.40
C30H28N4O10Pb2
1018.96
cryst syst
space group
a (Å)
triclinic
monoclinic
P21/c
orthorhombic
Fdd2
monoclinic
C2/m
triclinic
̅
P1
P1
̅
̅
6.8839(15)
8.8678(19)
10.965(2)
90.466(3)
102.738(3)
101.102(3)
639.8(2)
2
12.5956(17)
13.2999(18)
9.7711(13)
14.2347(12)
19.772(2)
10.8817(10)
22.976(13)
19.587(11)
10.776(6)
11.795(2)
13.2729(11)
13.9455(12)
118.039(1)
105.782(1)
92.554(1)
1815.8(4)
2
b (Å)
c (Å)
α (deg)
β (deg)
101.025(2)
101.912(7)
γ (deg)
V (Å3)
1606.7(4)
4
3062.6(5)
8
4745(5)
4
Z
T (K)
296(2)
1.289
296(2)
2.032
920.0
10.518
12 020
2985
296(2)
2.132
1840.0
11.036
6854
296(2)
2.064
2760.0
10.685
18 162
4544
296(2)
1.864
ρcalc (g/cm3)
F(000)
260.0
960.0
μ (Mo Kα, mm−1
total reflns
unique reflns
)
0.081
9.315
4770
13 017
2358
1875
6528
no. of observations
no. of params
1432
2349
1648
3405
5330
172
199
101
333
415
a
R1
0.0424
0.1167
1.019
0.0284
0.0716
0.0254
0.0532
1.063
0.0482
0.1327
1.074
0.0273
b
wR2
0.0656
c
GOF
1.030
1.083
a
b
c
2
R1 = ∑∥Fo| − |Fc|/∑|Fo|. wR2 = {∑w(Fo2 − Fc2)2/∑w(Fo )2}1/2. GOF = {∑w(Fo2 − Fc2)2/(n − p)}1/2, where n = number of reflections and p =
total numbers of parameters refined.
chloride (80 mmol) was added dropwise within 20 min, and the
solution was stirred at room temperature for 60 h. The resulting
solution was added to 500 mL of 10% aq K2CO3, and the mixture was
further stirred at room temperature for 1 h. The mixture was then
extracted with CH2Cl2 (3 × 50 mL). The combined organic layers
were washed with saturated NaHCO3 (500 mL) and NaCl (500 mL),
respectively, and dried with anhydrous MgSO4, and the solvent was
removed in vacuo to yield the crude product. Purification by silica gel
chromatography using 100−200 mesh ZCX II eluted by petroleum
ether−ethyl acetate (1:2, v/v) gave compound 1 (4.52 g, 91%). Anal.
Calcd. for C15H12N4: C, 72.56; H, 4.87; N, 22.57. Found: C, 72.57; H,
4.68; N, 22.75. IR (KBr disk): 2960 (w), 2918 (w), 2857 (w), 2232
(m), 1596 (s), 1472 (w), 1446 (m), 1407 (m), 1350 (m), 1226 (m),
1553 (m), 1470 (w), 1442 (m), 1403 (m), 1355 (m), 1221 (m), 980
(m), 919 (w), 862 (m), 780 (m), 460 (m) cm−1.
Preparation of [Pb3L2−3]n (4). A mixture of Pb(Ac)2 3H2O (38
mg, 0.1 mmol), BPCP ligand (25 mg, 0.1 mmol), and pyridine/H2O/
EtOH (1/1/1, 5 mL) was sealed in a 23 mL Teflon-lined stainless steel
container and heated at 130 °C for 5 days, then cooled to room
temperature at a rate of 15 °C·h−1. The colorless prisms of 4 were
collected and washed with EtOH and dried in air. Yield: 30 mg (60%,
based on Pb). Anal. Calcd. for C45H36N6O12Pb3: C, 36.66; H, 2.46; N,
5.70. Found: C, 36.58; H, 2.53; N, 5.90. IR (KBr disk): 2960 (w),
2916 (w), 2855 (w), 1595 (s), 1559 (m), 1475 (w), 1449 (m), 1404
(m), 1350 (m), 1222 (m), 980 (m), 921 (w), 860 (m), 782 (m), 470
(m) cm−1.
Preparation of [(Pb2L2−2)·2H2O]n (5). A mixture of Pb(Ac)2
3H2O (38 mg, 0.1 mmol), BPCP ligand (25 mg, 0.1 mmol), 4,4′-
bipyridine (9 mg, 0.05 mmol) (11 mg, 0.05 mmol), and pyridine/
H2O/EtOH (1/1/1, 5 mL) was sealed in a 23 mL Teflon-lined
stainless steel container and heated at 160 °C for 5 days, then cooled
to room temperature at a rate of 1.5 °C·h−1. The colorless blocks of 5
were collected and washed with EtOH and dried in air. Yield: 33 mg
(67%, based on Pb). Anal. Calcd. for C30H28N4O10Pb2: C, 35.36; H,
2.77; N, 5.50. Found: C, 35.31; H, 2.93; N, 5.72. IR (KBr disk): 3339
(m), 2952 (w), 2910 (w), 2840 (w), 1584 (s), 1548 (m), 1468 (w),
1440 (m), 1400 (m), 1352 (m), 1221 (m), 978 (m), 919 (w), 866
(m), 781 (m), 450 (m) cm−1.
X-ray Crystal Structure Determination. Crystallographic data of
1−5 were collected at 296 K on a Bruker Smart APEXII-CCD Area
Detector instrument with Mo Kα monochromated radiation (λ =
0.71073 Å) using the ω−φ scan technique. Data were reduced using
SAINTPLUS, and an empirical absorption correction was applied
using the SADABS program. The crystal structures were solved by the
direct method19 refined on F2 by full-matrix least-squares using
anisotropic displacement parameters for all non-hydrogen atoms. All
the H atoms in 1−5 were introduced at the calculated positions and
included in the structure-factor calculations. All the calculations were
performed on a Dell workstation using the SHELXTL-97 crystallo-
graphic software package. A summary of key crystallographic
information for 1−5 is given in Table 1. CCDC 872267 (1),
1
989 (m), 926 (w), 861 (m), 784 (m), 479(m) cm−1. H NMR (400
MHz, CDCl3): δ 8.63 (d, J = 4 Hz, 2H, ArH), 7.54 (s, 2H, ArH), 7.34
(d, J = 4 Hz, 2H, ArH), 2.75 (t, J = 8 Hz, 4H, CH2), 2.03 (q, J = 8 Hz,
2H, CH2).
Preparation of [PbL2−]n (2). A mixture of Pb(Ac)2 3H2O (38 mg,
0.1 mmol), BPCP ligand (25 mg, 0.1 mmol), and pyridine/H2O/
EtOH (1/1/1, 5 mL) was sealed in a 23 mL Teflon-lined stainless steel
container and heated at 130 °C for 5 days, then cooled to room
temperature at a rate of 1.5 °C·h−1. The colorless prisms of 2 were
collected and washed with EtOH and dried in air. Yield: 32 mg (65%,
based on Pb). Anal. Calcd. for C15H12N2O4Pb: C, 36.66; H, 2.46; N,
5.70. Found: C, 36.39; H, 2.33; N, 5.92. IR (KBr disk): 2964 (w),
2915 (w), 2856 (w), 1597 (s), 1553 (m), 1472 (w), 1447 (m), 1406
(m), 1352 (m), 1226(m), 987 (m), 926 (w), 860 (m), 784 (m), 478
(m) cm−1.
Preparation of [PbL2−]n (3). A mixture of Pb(Ac)2 3H2O (38 mg,
0.1 mmol), BPCP ligand (25 mg, 0.1 mmol), 4,4′-bipyridine (9 mg,
0.05 mmol), and pyridine/H2O/EtOH (1/1/1, 5 mL) was sealed in a
23 mL Teflon-lined stainless steel container and heated at 130 °C for 5
days, then cooled to room temperature at a rate of 1.5 °C·h−1. The
colorless blocks of 3 were collected and washed with EtOH and dried
in air. Yield: 27 mg (53%, based on Pb). Anal. Calcd. for
C15H12N2O4Pb: C, 36.66; H, 2.46; N, 5.70. Found: C, 36.49; H,
2.83; N, 5.90. IR (KBr disk): 2962 (w), 2912 (w), 2850 (w), 1594 (s),
5340
dx.doi.org/10.1021/cg300900m | Cryst. Growth Des. 2012, 12, 5338−5348

Crystal Growth & Design
Article
Figure 1. (a) View of the molecular structure of BPCP (1). (b) View of the one-dimensional chain structure formed via H-bonding interactions in 1
extending along the c axis. Atom color codes: H, pink; N, blue; and C, green. All H atoms except those related to H-bonding interactions were
omitted for clarity.
872268 (2), 872271 (3), 872269 (4), and 872278 (5) contain the
supplementary crystallographic data. These data can be obtained free
of charge via www.ccdc.cam.ac.uk/conts/retrieving.html (or from the
Cambridge Crystallographic Data Center, 12 Union Road, Cambridge
CB2 1EZ, U.K.; fax: (44) 1223 336-033. E-mail: deposit@ccdc.cam.ac.
uk). Selected bond lengths and angles for 2−5 are listed in Table S1
(see Table S1 in the Supporting Information).
formation of different superstructures. A similar phenomenon is
observed in the reports by Tong7c and Hu.21a The preparation
of polymorph 4 is similar to that of polymorph 2, except that
the cooling rate of 1.5 °C·h−1 was replaced by 15 °C·h−1.
Notably, when the reaction temperature was raised up to 160
°C, complex 5 was generated through the similar manner to
that described for 3. Significantly, the use of pyridine to adjust
the pH value of the reaction systems is another key point for
the crystallization of 2−5, and when other basic reagents, such
as NaOH, KOH, and 2,6-dimethylpyridine, were used instead,
crystalline products suitable for X-ray diffraction could not be
obtained under similar conditions.
Compounds 1−5 were stable toward oxygen and moisture. 1
was soluble in CH3Cl, MeOH, DMF, and DMSO, but 2−5
were almost insoluble in common organic solvents. The
elemental analyses of 1−5 were consistent with their chemical
formula. The1H NMR spectrum of 1 in CDCl3 exhibited one
singlet and two doublet for the phenyl groups at 8.63 ppm (d, J
= 4 Hz), 7.54 ppm (s), 7.34 ppm (d, J = 4 Hz), and the
bridging methylene groups at 2.75 (t, J = 8 Hz), 2.03 (q, J = 8
Hz). In the IR spectra of 1, the strong bands at 2232 cm−1 were
assigned to be the CN stretching vibration.22 The IR spectra
of 2−5 showed peaks in the range of 1548−1559 and 1468−
1474 cm−1, suggesting that the CN groups hydrolyzed to
COOH groups.23 The strong peaks at about 860 cm−1, and
middle peaks in the range of 449−477 cm−1, mean the
existence of pyridyl groups in the complexes 1−5.24 The PXRD
patterns of 2−5 were matched with the simulated patterns
generated from their single-crystal data (see the Supporting
Information, Figure S1).
RESULTS AND DISCUSSION
■
Synthetic and Spectral Aspects. Reactions of 1,3-bis(4-
pyridyl)propane-N,N′-dioxide with 10 equiv of (Me)3SiCN and
4 equiv of benzoyl chloride in CH2Cl2 produced a new flexible
1,3-bis(4-pyridyl-3-cyano)propane (1) in 91% yield (Scheme
1).
Recent studies have revealed that the in situ ligand
transformation reaction may occur during hydro(solvo)thermal
reactions, which is currently regarded as a feasible and effective
strategy to obtain novel CPs that are inaccessible or not easily
achieved by the conventional methods.20 However, the
controlled synthesis of supramolecular isomers is still a major
challenge.5 Small changes in one or more of the variables of
hydrothermal reactions, such as reaction temperature, pH value,
duration, and the presence of other contributing additives,
either the solvent or other species, have a profound influence
on the crystallization outcome.7c,21 As far as these factors are
concerned, polymorphs 2−4 and their polymorphic frame-
works 5 were successfully obtained by in situ reaction of BPCP
with Pb(II) acetate through tuning the solvothermally temper-
ature, reaction cooling rate, and additive. According to our
experimental results, the polymorphs 3 and 2 were
solvothermally prepared from Pb(II) acetate and the BPCP
ligand in the presence of 4,4′-bipyridine, or not, at 130 °C,
respectively. Interestingly, although 4,4′-bipyridine does not
participate in the structure construction, we cannot obtain the
product 3 without the addition of 4,4′-bipyridine. This fact
strongly suggests that the additive can effectively promote the
Crystal Structure of 1. Compound 1 crystallizes in the
triclinic space group P1,and its asymmetric unit contains one
̅
BPCP molecule (Figure 1a). As shown in Figure 1b, the N
atoms of the pyridyl groups interact with the H atoms of the
pyridyl groups with C5 and C11 [C5···N3 (1 − x, 1 − y, 1/2 −
z); C11···N1 (1 − x, 1 − y, 1 − z)] to afford intermolecular
5341
dx.doi.org/10.1021/cg300900m | Cryst. Growth Des. 2012, 12, 5338−5348

Crystal Growth & Design
Article
hydrogen bonds, forming a 1D chain extending along the c axis
(Figure 1b).
Crystal Structure of 2. Polymorph 2 crystallizes in the
monoclinic space group P21/c, and its asymmetric unit contains
one PbL2− unit. Each Pb atom adopts a distorted octahedral
geometry and is coordinated by four O atoms of four bridging
carboxylate groups from four different L2− ligands and two N
atoms from two L2− ligands (Figure 2a). The mean Pb−O
bond length (2.582(4) Å) is shorter than that of [Pb(pydc)]n
(H2pydc = pyridine-2,6-dicarboxylic acid (2.648(8) Å), while
the mean Pb−N bond length (2.512(4) Å) is shorter than that
in [Pb(pydc)]n (2.486(3) Å).25 The L2− ligand in 2 only takes
TT conformation (Scheme 2a), and the carboxylate groups
display μ2-η1:η1- or μ2-η2-bridged modes. Thus, each L2− ligand
in 2 acts as a μ4-bridge to link four Pb(II) atoms. Pb1 and its
symmetry-related Pb1A are bridged by two L2− ligands to
generate a dinuclear [Pb2L2−2] ringlike unit with an
approximate diameter of 6.41 Å (between C8 and C8A) ×
13.42 Å (between Pb1 and Pb1A) (Figure 2b). Each Pb1 atom
in the [Pb2L2−2] unit interconnects its equivalent ones via
bridging carboxylate groups to form a 1D [Pb2L2−2]n double
chain extending along the c axis (Figure 2c). One pair of rings
(green and cyan) is arranged in an almost vertical way. The
aforementioned 1D double chains are further connected to
adjacent ones by Pb1 atoms, leading to a 2D ladder-like
structure in the ac plane (see the Supporting Information,
Figure S2). Each 2D structure is further connected by
carboxylate groups to generate a 3D porous structure with
1D channels (6.64 Å × 11.34 Å) running along the c axis
(Figure 2d). The effective solvent accessible volume of 163.7 Å3
per unit cell (10.2% of the total cell volume calculated by the
Platon program) is filled with guest molecules.26 A better
insight into the nature of 2 can be achieved by the application
of a topological approach, namely, reducing multidimensional
structures to simple node-and-linker nets. As discussed above,
the L2− ligands act as 3-connected nodes and Pb(II) centers act
as 6-connected nodes. In this way, the resulting structure of 2 is
symbolized as a (3,6)-connected (4·52)(42·52·67·73·8) topology
(Figure 2e).
Crystal Structure of 3. For polymorph 3, there are the
same components as that of 2 in the fundamental unit (Figure
3a), however, the L2− ligand takes a different conformation,
TT″ (Scheme 2c), and the two carboxylate groups display the
same μ2-η1:η1-bridged modes, which are distinguished from that
of 2. Herein, different from that of 2, first, 3 crystallizes in the
orthorhombic space group Fdd2, and its asymmetric unit only
contains half a PbL2− unit. Second, different from that of 2, the
structural feature of 3 is that Pb1 and Pb1A are linked by one
L2− ligand to afford a [Pb2L2−] semi-ring-like unit. Each Pb1
atom in the [Pb2L2−] unit interconnects its equivalent ones via
bridging carboxylate groups to form a 1D [Pb2L2−]n chain along
the b axis (see the Supporting Information, Figure S3).
Moreover, each 1D chain is connected to neighboring ones by
Pb1 atoms to afford a 2D sheet in the ab plane with square
meshes (12.18 Å × 12.18 Å) (Figure 3b). Finally, different from
that of 2, the different packing mode in 3 is that the 2D layers
are further connected by L2− bridges to generate a 3D
framework with 1D channels (11.11 Å × 12.18 Å) running
along the c axis (Figure 3c). The bridging ligands are located in
the 1D channels, so there is still approximately 3.7% of the
crystal volume to be filled by solvent molecules, which is much
lower than that of 2. Topologically, both L2− ligands and Pb
Figure 2. (a) View of the coordination environments of the Pb1 center
in 2 with labeling schemes. Symmetry codes: (A) −x + 1, −y + 1, −z +
1; (B) −x + 1, y − 1/2, −z + 1/2; (C) −x, −y + 1, −z. (b) View of
one dinuclear [Pb2L2−2] ringlike unit of 2. Symmetry codes: (A) −x +
1, −y + 1, −z + 1. (c) View of a section of the 1D double chain
5342
dx.doi.org/10.1021/cg300900m | Cryst. Growth Des. 2012, 12, 5338−5348

Crystal Growth & Design
Article
Figure 2. continued
extending along the c axis. (d) View of a 3D porous structure in 2
along the c axis. (e) Topological view showing the equivalent 3D
framework of 2. The purple pillars represent the 1D channel in 2.
Atom color codes: Pb, cyan; O, red; N, blue; and C, green. All
hydrogen atoms are omitted for clarity.
atoms act as a 4-connected node, and thus the 3D structure of 3
can be rationalized as a (66)2 net (Figure 3d).
Crystal Structure of 4. For polymorph 4, there are the
same components as that of 2 and 3 in the fundamental unit,
which crystallizes in the monoclinic space group C2/m, and its
asymmetric unit contains half a Pb3L2− unit. As shown in
3
Figure S4 (see the Supporting Information), the Pb atoms in 4
adopt two different coordination geometries. Both Pb1 and Pb2
are seven-coordinated, each coordinated by six O atoms of four
bridging carboxylate groups from four different L2− ligands and
one N atom from one L2− ligand, to complete a pentagonal
bipyrimidal coordination environment (see the Supporting
Information, Figure S4a,b). The mean Pb1−O bond length
(2.621(5) Å) is longer than that of {[Pb6(pydc)6]·H2O}n
(2.529(7) Å), while the Pb1−N bond length (2.514(10) Å)
is longer than that in {[Pb6(pydc)6]·H2O}n (2.492(3) Å).27
The mean Pb2−O bond length (2.637(3) Å) is shorter than
that of [Pb(dpaea)(H2O)]2·[Pb(dpaea)]·6H2O (H2dpaea =
N,N-bis[(6-carboxypyridin-2-yl)methyl]ethylamine, 2.467(2)
Å).28 Pb3 is eight-coordinated by four O atoms of four
bridging carboxylate groups and four N atoms from four
different L2− ligands (see the Supporting Information, Figure
S4c), and the coordination geometry around Pb3 may be
described as a distorted trigonal dodecahedron. The mean
Pb3−O and Pb3−N bond lengths (2.715(5) vs 2.662(1) Å) are
shorter than those of the corresponding ones in [Pb(pydc)]n
(2.612(8) vs 2.692(2) Å).29 In 4, the Pb−N and Pb−O bond
lengths fall in the ranges of 2.361(8)−2.829(8) and 2.491(13)−
2.669(14) Å, respectively, which are comparable to the
previously reported values.30 The L2− ligand in 4 takes
conformations TT and TT′ (Scheme 2a,b), and the carboxylate
groups display μ2-η2:η1- or μ2-η2-bridged modes.
In 4, Pb3 and Pb3A atoms are linked by two L2− ligands to
form a dinuclear ringlike [Pb2L2−2] unit with a rough diameter
of 5.92 Å (between C23 and C23A) × 14.04 Å (between Pb3
and Pb3A), similar to that observed in 2 (Figure 4a). Each Pb3
atom in the [Pb2L2−2] unit interconnects its equivalent ones via
bridging carboxylate groups to form a 1D [Pb2L2−2]n chain
along the a axis (Figure 4b). Such 1D chains are linked by Pb1
and Pb2 atoms to afford a 2D network with rectangular grids
(6.09 × 10.84 Å) in the ab plane (Figure 4c). Other L2− ligands
act as a pillar to link the adjacent 2D networks to form a 3D
framework with dimensions of 10.84 × 14.86 × 19.59 Å3 along
the ac plane (Figure 4d). This framework was big enough to
allow the other net to penetrate to form a 2-fold inter-
penetrating framework, which can be described as a trinodal
(3,6,10)-connected topology with a point symbol of (43)-
(44·610·8)(48·624·89·104) (Figure 4e). The Platon program
analysis suggests that approximately 12.7% (4) of the crystal
volume is accessible to the solvents, which is a little higher than
that of 2 (10.2%).
Crystal Structure of 5. Complex 5 crystallizes in the
Figure 3. (a) View of the coordination environments of the Pb1 center
in 3 with labeling schemes. Symmetry codes: (A) −x, −y − 1, −z; (B)
−x + 1/4, y − 1/4, z − 1/4; (C) x − 1/4, −y − 3/4, z − 1/4; (D) −x
− 1/2, −y − 1/2, z; (E) x + 1/2, y − 1/2, z; (F) x + 3/4, −y − 3/4, z
triclinic space group P1, and its asymmetric unit contains one
̅
Pb2L2−2 unit and two H2O molecules. As shown in Figure 5a,b,
each Pb atom in 5 is eight-coordinated by two nitrogen atoms
5343
dx.doi.org/10.1021/cg300900m | Cryst. Growth Des. 2012, 12, 5338−5348

Crystal Growth & Design
Article
distorted trigonal dodecahedron. The mean Pb1−O and Pb1−
N bond lengths (2.682(2) vs 2.597(1) Å) are longer than those
of the corresponding ones in 4 (2.657(2) vs 2.588(1) Å). The
average Pb2−O and Pb2−N bond length (2.758(3) vs
2.600(5) Å) is longer than that of [Pb(HOIP)(pyc)2]2
(2.460(5) vs 2.563(5) Å; HOIP = 2-(4-hydroxylbenzene)
imidazo[4,5-f ]1,10-phenanthroline, Hpyc = pyridyl-2-carbox-
ylic acid).31 The L2− ligand in 5 takes conformations TT′ and
TG″ (Scheme 2b,f), and the carboxylate groups display μ2-
η2:η1- or μ2-η2-bridged modes. As shown in Figure 5c,d, it was
Figure 3. continued
− 1/4; (G) −x − 3/4, y − 1/4, z − 1/4. (b) View of a 2D sheet in 3
extending along the ab plane. (c) View of a 3D framework in 3 along
the b axis. (d) Topological view showing the equivalent 3D framework
of 3. Atom color codes: Pb, cyan; O, red; N, blue; and C, green. All
hydrogen atoms are omitted for clarity.
interesting that there existed two kinds of dinuclear [Pb2L2−
]
2
units in 5. One of the dinuclear [Pb2L2−2] units showed a little
flat ring with a rough diameter of 5.75 Å (between C23 and
C23A) × 14.04 Å (between Pb2 and Pb2A) (Figure 5c).
Another displayed a distorted ring with an approximate 6.32 Å
(between C9 and C9A) × 12.54 Å (between Pb1 and Pb1A)
(Figure 5d). These two [Pb2L2−2] units are interconnected by
bridging carboxylate groups in a alternate fashion to form a 1D
[Pb2L2−2]n ladder-like chain (Figure 5e). Such 1D chains are
further linked to its adjacent ones by Pb1 and Pb2 atoms to
afford a 2D undulant network with a 6-connected (36·46·53)
topology (Figure 5e−g). The weak interactions (2.925(2) Å)
between Pb2 and O9 and the hydrogen-bonding interactions
[C4−H4···O9, 2.583(5) (Å)] between O atoms of H2O
molecules (O9) in one network and H atoms of pyridine rings
in the adjacent network connect the 2D networks to afford a
3D framework with 1D channels (4.20 Å × 7.50 Å) looking
along the c axis. There is still approximately 19.9% of the crystal
volume to be filled by solvent molecules, which is much higher
than that of 2−4.
Effects of Reaction Conditions and Conformations of
Ligand on the Formation of Four Coordination
Polymers. Polymorphism, which can be considered a specific
subset of supramolecular isomerism, is particularly rare for
coordination polymers.7 To the best of our knowledge, there is
only one case reported about the polymorphs constructed from
a single flexible linked dicarboxylate as the building block
materials.6a Fortunately, the present study shows that the new
flexible ligand, BPCP, can also act as a convenient building
block for the construction of novel CPs, whose syntheses can
be easily accomplished by solvothermal reactions. During the
preparation of four novel coordination polymers, process
temperature, cooling rate, and additive are three key factors
in controlling the topologies of CPs. For example, by fine-
tuning the reaction temperature to 130 and 160 °C, complexes
3 and 5 have been synthesized, respectively. Complex 3
possesses a 3D metal−organic framework with a 1D channel
(11.11 Å × 12.18 Å), in which dinuclear semi-ring-like
[Pb2L2−] units are bridged by L2− ligands. Complex 5 features
a 3D supramolecualr architecture constructed from 2D
undulant layer motifs joined by hydrogen-bonding interactions
and weak interactions. The difference of the bridging mode and
the conformation of L2− ligands in the two complexes must be
induced by different reaction temperatures, which should be
mainly responsible for the different architectures of 3 and 5.
The L2− ligand in 3 adopts a μ4-bridging mode and TT″
conformation to link Pb(II) centers, resulting in a dinuclear
semi-ring-like [Pb2L2−] unit. The L2− ligand in 5 takes a μ4-
bridging mode and TT′ and TG″ conformations to connect
Pb(II) atoms, leading to two dinuclear ringlike [Pb2L2−2] units.
Thus, this result reveals that, for a more flexible ligand, the
assembly will be more dependent on the temperature.
Comparing polymorph 2 with 3, the addition of 4,4′-bipyridine
Figure 4. (a) View of one dinuclear [Pb2L2−2] ringlike unit of 4.
Symmetry codes: (A) −x + 5/2, −y + 1/2, −z. (b) View of a section of
the 1D chain along the c axis. (c) View of a 2D network in 4 along the
ab plane. (d) View of a 3D framework in 4 along the b axis. The purple
and yellow pillars represent 1D channels in 4. (e) Schematic
representation of the trinodal (3,6,10)-connected topology with a
point symbol of (43)(44·610·8)(48·624·89·104). Atom color codes: Pb,
cyan; O, red; N, blue; and C, green. All hydrogen atoms are omitted
for clarity.
from two L2− ligands, five carboxylate oxygen atoms from four
different L2− ligands, and one coordinated water molecule, and
thus the coordination geometry around Pb may be described a
5344
dx.doi.org/10.1021/cg300900m | Cryst. Growth Des. 2012, 12, 5338−5348

Crystal Growth & Design
Article
Figure 5. (a, b) View of the coordination environments of Pb centers in 5 with labeling schemes. Symmetry codes: (A) −x + 1, −y + 2, −z + 2; (B)
x − 1, y − 1, z − 1; (C) −x + 1, −y + 2, −z + 1 ; (D) −x, −y + 1, −z + 1. (c) View of one dinuclear [Pb2L2−2] ringlike unit of 5. (d) View of one
distorted dinuclear [Pb2L2−2] ringlike unit of 5. (e) View of a section of the 1D ladder-like chain along the c axis. (f) View of a 2D network in 5 in the
bc plane. (g) A schematic representation of the 6-connected (36·46·53) topology. The red dashed lines represent hydrogen-bonding interactions.
Atom color codes: Pb, cyan; O, red; N, blue; and C, green.
promotes the formation of 3 under similar reaction conditions.
A similar phenomenon can be documented by recent reports by
Tong7c and Hu.21a Thus, this fact strongly suggests that the
additive can effectively promote the formation of different
superstructures. Additionally, the preparation of polymorph 4 is
similar to that of polymorph 2, except that the cooling rate of
1.5 °C·h−1 was replaced by 15 °C·h−1. The result demonstrates
that this crystallization condition can also play another
important role in the formation of complexes. To our
knowledge, there is no case reported about the polymorphs
constructed from a subtle difference in cooling rate as a
dominant structural factor.
Photoluminescence Properties. The photoluminescent
properties of 1−5 and H2L in the solid state at room
temperature were studied. The result demonstrated that the
BPCP ligand (1) did not show photoluminescent properties.
5345
dx.doi.org/10.1021/cg300900m | Cryst. Growth Des. 2012, 12, 5338−5348

Crystal Growth & Design
Article
The emission spectra of supramolecular isomers 2−5 and the
H2L ligand are very similar, as shown in Figure 6. Upon
process. The final residue of ca. 54.3, 54.9, and 54.7% for
polymorphs 2−4, respectively, is in agreement with the
percentage of PbCO3 in all cases (calcd. 54.5%), as observed
in the previous studies.32a,33 The TGA of 5 exhibits two main
steps of weight loss. A weight loss of 6.1% in the temperature
range of 50−119 °C shows the release of all guest water
molecules (calcd. 3.5%). The second step of weight loss from
378 °C corresponds to the thermal decomposition of the
organic groups. The final residue of ca. 49.3% is in agreement
with the percentage of PbCO3 in 5 (calcd. 48.9%). In addition,
the weight loss, being an endothermic process, occurred at ca.
119 °C for 5, 312 °C for 4, 390 °C for 2, and 393 °C for 3,
implying an increase in thermal stability from compounds 5, 4,
2, and to 3.
CONCLUSIONS
■
In conclusion, three novel true polymorphous CPs and one of
their polymorphic frameworks were successfully synthesized
employing the same ratio of reaction materials, containing a
new flexible linker BPCP with a relatively long spacer, via an in
situ ligand transformation reaction, cooperating with fine
control over synthetic conditions. The structural results show
that utilizing the flexible ligands is a deliberate strategy to
achieve diversity in CP structures, which may help chemists
obtain new polymorphs. Analyses of synthetic conditions,
structures, and coordination modes of the L2− ligand reveal that
reaction temperature, cooling rate, and additive are three key
factors to products and coordination conformation of the L2−
ligand . The L2− ligands in 2−5 adopt a μ4-bridging mode, and
a TT, TT′, TT″, or TG″ conformation, to link Pb(II) centers,
resulting in a dinuclear ringlike [Pb2L2−2] unit in 2 and 4, a
dinuclear semi-ring-like [Pb2L2−] unit in 3, and two dinuclear
ringlike [Pb2L2−2] units in 5, respectively. Based on these
different building units, polymorphs 2 and 4 display a 3D
framework with 1D channels. Polymorph 3 features a 2-fold
interpenetrating framework with a trinodal (3,6,10)-connected
topology with a point symbol of (43)(44·610·8)(48·624·89·104).
Polymorphic framework 5 exhibits a 3D supramolecualr
architecture built up from 2D undulant layer motifs joined by
hydrogen-bonding interactions and weak interactions. The
differences in conformation and packing alignment should be
mainly responsible for the different architectures of complexes
2−5. Most importantly, the study also reveals that the structural
differences of 2−5 result in the differences in photo-
luminescence properties. This work may provide a useful
approach for the design and construction of other structural
isomeric crystalline materials, which further helps us to
understand the relationships between structures and properties.
Figure 6. Emission spectra of 2−5 in the solid state at ambient
temperature.
excitation at 371 nm, the strongest emission peak for the free
H2L ligand appears at 435 nm, corresponding to the n → π*
transitions. For 2−5, excitation of the microcrystalline samples
at 384, 387, 378, 363, and 351 nm leads to the generation of
intense fluorescent emissions (Figure 6), with similar maximum
peaks observed in the blue region (2, 543 nm; 3, 535 nm; 4,
520 nm; and 5, 540 nm), which may be attributed to the ligand-
centered π → π* electronic transitions.32 The different
emission bands of compounds 2−5 may be assigned to the
coordination diversities of the Pb(II) ion centers and the rigid
differences of these Pb(II) coordination frameworks.
Thermogravimetric Analysis. To investigate the thermal
stability of 2−5, TGA and DSC experiments were performed
for these materials under a N2 atmosphere. As depicted in
Figure 7, the thermograms of polymorphs 2−4 show similar
ASSOCIATED CONTENT
* Supporting Information
■
S
Table of selected bond lengths and angles for 2−5, PXRD
patterns for 2−5, view of 2 along the ac plane, view of 3 along
the b axis, and view of coordination environments of Pb centers
in 4. Crystal structure data for 1−5 in CIF format. This material
is available free of charge via the Internet at http://pubs.acs.org.
Figure 7. TGA and DSC curves of compounds 2−4.
profiles. The three polymorphs are thermally very stable up to
312 °C. Because there are no solvent molecules in the
frameworks, there is a plateau region ranging from 25 to 390 °C
in 2, 393 °C in 3, and 312 °C in 4, followed by a sudden
decrease in the weight, suggesting the onset of the
decomposition temperature of the complexes. This can be
confirmed by DSC analysis. The DSC curves show an
endothermic peak, corresponding to the decomposition
AUTHOR INFORMATION
Corresponding Author
*E-mail: lyhxxjbm@126.com (B.-M.J.), dcx@zzu.edu.cn (C.D.).
■
Notes
The authors declare no competing financial interest.
5346
dx.doi.org/10.1021/cg300900m | Cryst. Growth Des. 2012, 12, 5338−5348

Crystal Growth & Design
Article
Growth Des. 2008, 8, 3233. (d) Wu, S.-T.; Long, L.-S.; Huang, R.-B.;
Zheng, L.-S. Cryst. Growth Des. 2007, 7, 1746. (e) Dybtsev, D. N.;
Chun, H.; Kim, K. Chem. Commun. 2004, 1594. (f) Pan, L.; Liu, H.;
Lei, X.; Huang, X.; Olson, D. H.; Turro, N. J.; Li, J. Angew. Chem., Int.
Ed. 2003, 42, 542.
ACKNOWLEDGMENTS
■
We are grateful to the Natural Science Foundation of China
(Grant No.21072089) and the Science and Technology
Innovation Team support programs of Henan Province
University (No. 2012IRTSTHN019) for the financial support.
(13) (a) Yu, F.; Kong, X.-J.; Zheng, Y.-Y.; Ren, Y.-P.; Long, L.-S.;
Huang, R.-B.; Zheng, L.-S. Dalton Trans. 2009, 9503. (b) Wang, B.;
̂ ́
Cote, A. P.; Furukawa, H.; O’Keeffe, M.; Yaghi, O. M. Nature 2008,
REFERENCES
■
453, 207. (c) Luo, F.; Batten, S. R.; Che, Y.; Zheng, J.-M. Chem.Eur.
(1) (a) Zhang, J.-P.; Huang, X.-C.; Chen, X.-M. Chem. Soc. Rev. 2009,
38, 2385. (b) Moulton, B.; Abourahma, H.; Bradner, M. W.; Lu, J.;
McManus, G. J.; Zaworotko, M. J. Chem. Commun. 2003, 1342.
(c) Abourahma, H.; Moulton, B.; Kravtsov, V.; Zaworotko, M. J. J. Am.
Chem. Soc. 2002, 124, 9990. (d) Moulton, B.; Zaworotko, M. J. Chem.
Rev. 2001, 101, 1629.
(2) Caskey, S. R.; Wong-Foy, A. G.; Matzger, A. J. Inorg. Chem. 2008,
47, 7751.
(3) Allen, F. H. Acta Crystallogr., Sect. B 2002, 58, 380.
J. 2007, 13, 4948.
(14) (a) Zheng, B.; Dong, H.; Bai, J.; Li, Y.; Li, S.; Scheer, M. J. Am.
Chem. Soc. 2008, 130, 7778. (b) Dong, Y.-B.; Jiang, Y.-Y.; Li, J.; Ma, J.-
P.; Liu, F.-L.; Tang, B.; Huang, R.-Q.; Batten, S. R. J. Am. Chem. Soc.
2007, 129, 4520. (c) Fang, R.-Q.; Zhang, X.-M. Inorg. Chem. 2006, 45,
4801. (d) Forster, P. M.; Stock, N.; Cheetham, A. K. Angew. Chem., Int.
Ed. 2005, 44, 7608. (e) Tong, M.-L.; Kitagawa, S.; Chang, H.-C.;
Ohba, M. Chem. Commun. 2004, 418. (f) Forster, P. M.; Burbanki, A.
́
R.; Livage, C.; Ferey, G.; Cheetham, A. K. Chem. Commun. 2004, 368.
(4) (a) Brittain, H. G., Ed. Polymorphism in Pharmaceutical Solids;
Marcel Dekker: New York, 1999. (b) Byrn, S. R.; Pfeiffer, R. R.;
Stowell, J. G. Solid State Chemistry of Drugs, 2nd ed.; SSCI, Inc.: West
Lafayette, IN, 1999. (c) Bernstein, J. Polymorphism in Molecular
Crystals; Clarendon Press: Oxford, U.K., 2002. (d) Hilfiker, R., Ed.
Polymorphism in the Pharmaceutical Industry; Wiley-VCH: Weinheim,
Germany, 2006.
(5) (a) Li, D.-S.; Zhang, P.; Zhao, J.; Fang, Z.-F.; Du, M.; Zou, K.;
Mu, Y.-Q. Cryst. Growth Des. 2012, 12, 1697. (b) Wu, Y.-P.; Li, D.-S.;
Fu, F.; Dong, W.-W.; Zhao, J.; Zou, K.; Wang, Y.-Y. Cryst. Growth Des.
2011, 11, 3850. (c) Nauha, E.; Ojala, A.; Nissinen, M.; Saxell, H.
CrystEngComm 2011, 13, 4956. (d) Han, L.; Zhao, W.; Zhou, Y.; Li,
X.; Pan, J. Cryst. Growth Des. 2008, 8, 3504. (e) Zhang, J.-P.; Chen, X.-
M. Chem. Commun. 2006, 1689.
(6) (a) Yang, G.-P.; Hou, L.; Wang, Y.-Y.; Zhang, Y.-N.; Shi, Q.-Z.;
Batten, S. R. Cryst. Growth Des. 2011, 11, 936. (b) Li, Z.-G.; Wang, G.-
H.; Jia, H.-Q.; Hu, N.-H.; Xu, J.-W. CrystEngComm 2007, 9, 882.
(c) Peng, Y.-F.; Ge, H.-Y.; Li, B.-Z.; Li, B.-L.; Zhang, Y. Cryst. Growth
Des. 2006, 6, 994. (d) Gale, P. A.; Light, M. E.; Quesada, R. Chem.
Commun. 2005, 5864. (e) Li, B.; Peng, Y.; Li, B.; Zhang, Y. Chem.
Commun. 2005, 2333. (f) Huang, X.-C.; Zhang, J.-P.; Chen, X.-M. J.
Am. Chem. Soc. 2004, 126, 13218. (g) Kumar, V. S. S.; Pigge, F. C.;
Rath, N. P. Cryst. Growth Des. 2004, 4, 651. (h) Soldatov, D. V.;
Ripmeester, J. A.; Shergina, S. I.; Sokolov, I. E.; Zanina, A. S.;
Gromilov, S. A.; Dyadin, Y. A. J. Am. Chem. Soc. 1999, 121, 4197.
(7) (a) Hao, Z.-M.; Zhang, X.-M. Cryst. Growth Des. 2007, 7, 64.
(b) Huang, X.-C.; Zhang, J.-P.; Lin, Y.-Y.; Chen, X.-M. Chem.
Commun. 2005, 2232. (c) Tong, M.-L.; Hu, S.; Wang, J.; Kitagawa, S.;
Ng, S. W. Cryst. Growth Des. 2005, 5, 837. (d) Shin, D. M.; Lee, I. S.;
Cho, D.; Chung, Y. K. Inorg. Chem. 2003, 42, 7722.
(8) (a) Bond, A. D.; Boese, R.; Desiraju, G. R. Angew. Chem., Int. Ed.
2007, 46, 618. (b) Jetti, R. K. R.; Boese, R.; Thallapally, P. K.; Desiraju,
G. R. Cryst. Growth Des. 2003, 3, 1033.
(9) (a) Wang, Z.-W.; Ji, C.-C.; Li, J.; Guo, Z.-J.; Li, Y.-Z.; Zheng, H.-
G. Cryst. Growth Des. 2009, 9, 475. (b) Mahata, P.; Natarajan, S. Inorg.
Chem. 2007, 46, 1250. (c) Cao, R.; Sun, D. F.; Liang, Y. C.; Hong, M.
C.; Tatsumi, K.; Shi, Q. Inorg. Chem. 2002, 41, 2087.
(10) (a) Sun, D.; Xu, H.-R.; Yang, C.-F.; Wei, Z.-H.; Zhang, N.;
Huang, R.-B.; Zheng, L.-S. Cryst. Growth Des. 2010, 10, 4642.
(b) Mahata, P.; Sen, D.; Natarajan, S. Chem. Commun. 2008, 1278.
(c) Zuhayra, M.; Kampen, W. U.; Henze, E.; Soti, Z.; Zsolnai, L.;
Huttner, G.; Oberdorfer, F. A. J. Am. Chem. Soc. 2006, 128, 424.
(d) Long, L.-S.; Wu, Y.-R.; Huang, R.-B.; Zheng, L.-S. Inorg. Chem.
2004, 43, 3798.
(11) (a) Luo, F.; Che, Y.-x.; Zheng, J.-m. Cryst. Growth Des. 2009, 9,
1066. (b) Reger, D. L.; Watson, R. P.; Smith, M. D. Inorg. Chem. 2006,
45, 10077. (c) Cui, Y.; Evans, O. R.; Ngo, H. L.; White, P. S.; Lin, W.
B. Angew. Chem., Int. Ed. 2002, 41, 1159.
(15) (a) Yang, G.-P.; Wang, Y.-Y.; Liu, P.; Fu, A.-Y.; Zhang, Y.-N.;
Jin, J.-C.; Shi, Q.-Z. Cryst. Growth Des. 2010, 10, 1443. (b) Wang, H.;
Wang, Y.-Y.; Yang, G.-P.; Wang, C.-J.; Wen, G.-L.; Shi, Q.-Z.; Batten,
S. R. CrystEngComm 2008, 10, 1583. (c) Ghosh, S. K.; Bureekaew, S.;
Kitagawa, S. Angew. Chem., Int. Ed. 2008, 47, 3403. (d) Sun, R.; Wang,
S.; Xing, H.; Bai, J.; Li, Y.; Pan, Y.; You, X. Inorg. Chem. 2007, 46,
8451. (e) de Lill, D. T.; Cahill, C. L. Chem. Commun. 2006, 4946.
(16) (a) Wang, X. S.; Ma, S.; Forster, P. M.; Yuan, D.; Eckert, J.;
Lopez, J. J.; Murphy, B. J.; Praise, J. B.; Zhou, H.-C. Angew. Chem., Int.
Ed. 2008, 47, 7263. (b) Maspoch, D.; Ruiz-Molina, D.; Vaciana, J.
Chem. Soc. Rev. 2007, 36, 770. (c) Cheetham, A. K.; Rao, C. N. R.;
Feller, R. K. Chem. Commun. 2006, 4780. (d) Mosaoka, S.; Tanaka, D.;
Nakanishi, Y.; Kitagawa, S. Angew. Chem., Int. Ed. 2004, 43, 2530.
(17) (a) Gabriel, C.; Raptopoulou, C. P.; Psycharis, V.; Terzis, A.;
Zevou, M.; Mateescu, C.; Salifoglou, A. Cryst. Growth Des. 2011, 11,
382. (b) Liu, T.-F.; Lu, J.; Tian, C.; Cao, M.; Lin, Z.; Cao, R. Inorg.
̈
Chem. 2011, 50, 2264. (c) Davidovicha, R. L.; Stavilab, V.; Whitmire,
K. H. Coord. Chem. Rev. 2010, 254, 2193. (d) Li, D.-S.; Wu, Y.-P.;
Zhang, P.; Du, M.; Zhao, J.; Li, C.-P.; Wang, Y.-Y. Cryst. Growth Des.
2010, 10, 2037. (e) Li, X.; Weng, X.; Tang, R.; Lin, Y.; Ke, Z.; Zhou,
W.; Cao, R. Cryst. Growth Des. 2010, 10, 3228. (e) Liu, T.; Lv, J.; Shi,
L.; Guo, Z.; Cao, R. CrystEngComm 2009, 11, 583. (f) Zhang, L.; Li,
Z.-J.; Lin, Q.-P.; Qin, Y.-Y.; Zhang, J.; Yin, P.-X.; Cheng, J.-K.; Yao, Y.-
G. Inorg. Chem. 2009, 48, 6517. (g) Davidovicha, R. L.; Stavilab, V.;
Marinina, D. V.; Voita, E. I.; Whitmire, K. H. Coord. Chem. Rev. 2009,
253, 1316. (h) Yang, J.; Ma, J.-F.; Liu, Y.-Y.; Ma, J.-C.; Batten, S. R.
Inorg. Chem. 2007, 46, 6542.
(18) Zhang, L.-P.; Lu, W.-J.; Mak, T. C. W. Chem. Commun. 2003,
2830.
(19) Sheldrick, G. M. SHELXS-97 and SHELXL-97: Program for X-
ray Crystal Structure Solution; University of Goettingen: Goettingen,
̈
̈
Germany, 1997.
(20) (a) Zhu, H.-B.; Gou, S.-H. Coord. Chem. Rev. 2011, 255, 318.
(b) Zhao, H.; Qu, Z.-R.; Ye, H.-Y.; Xiong, R.-G. Chem. Soc. Rev. 2008,
37, 84. (c) Chen, X.-D.; Wu, H.-F.; Du, M. Chem. Commun. 2008,
1296. (d) Chen, X.-M.; Tong, M.-L. Acc. Chem. Res. 2007, 40, 162.
(21) (a) Li, Z.-G.; Wang, G.-H.; Jia, H.-Q.; Hu, N.-H.; Xu, J.-W.
CrystEngComm 2007, 9, 882. (b) Prior, T. J.; Rosseinsky, M. J. Inorg.
Chem. 2003, 42, 1564. (c) Li, J.; Yu, J.; Yan, W.; Xu, Y.; Xu, W.; Qiu,
S.; Xu, R. Chem. Mater. 1999, 11, 2600. (d) Gavezzotti, A. Acc. Chem.
Res. 1994, 27, 309.
(22) Li, L.-L.; Yuan, R.-X.; Liu, L.-L.; Ren, Z.-G.; Zheng, A.-X.;
Cheng, H.-J.; Li, H.-X.; Lang, J.-P. Cryst. Growth Des. 2010, 10, 1929.
(23) (a) Ji, B.-M.; Deng, D.-S.; Lan, H.-H.; Du, C.-X.; Pan, S.-L.; Liu,
B. Cryst. Growth Des. 2010, 10, 2851. (b) Liu, L.-L.; Ren, Z.-G.; Zhu,
L.-W.; Wang, H.-F.; Yan, W.-Y.; Lang, J.-P. Cryst. Growth Des. 2011,
11, 3479.
(12) (a) Zhang, K.-L.; Chang, Y.; Hou, C.-T.; Diao, G.-W.; Wu, R.;
Ng, S. W. CrystEngComm 2010, 12, 1194. (b) Sarma, R.; Kalita, D.;
Baruah, J. B. Dalton Trans. 2009, 7428. (c) Liu, G.-X.; Huang, Y.-Q.;
Chu, Q.; Okamura, T.-a.; Sun, W.-Y.; Liang, H.; Ueyama, N. Cryst.
(24) Liu, D.; Ren, Z.-G.; Li, H.-X.; Chen, Y.; Wang, J.; Zhang, Y.;
Lang, J.-P. CrystEngComm 2010, 12, 1912.
(25) Du, M.; Cai, H.; Zhao, X.-J. Inorg. Chim. Acta 2006, 359, 673.
5347
dx.doi.org/10.1021/cg300900m | Cryst. Growth Des. 2012, 12, 5338−5348

Crystal Growth & Design
Article
(26) Wells, A. F. Three-Dimensional Nets and Polyhedra; Wiley-
Interscience: New York, 1977.
(27) Xu, H.; Chao, Z.; Sang, Y.; Hou, H.; Fan, Y. Inorg. Chem.
Commun. 2008, 11, 1436.
(28) Pellissier, A.; Bretonnier
Delangle, P.; Mazzanti, M. Inorg. Chem. 2007, 46, 3714.
̀ ́
e, Y.; Chatterton, N.; Pecaut, J.;
(29) Wei, Y.; Hou, H.; Li, L.; Fan, Y.; Zhu, Y. Cryst. Growth Des.
2005, 5, 1405.
(30) (a) Peedikakkal, A. M. P.; Vittal, J. J. Cryst. Growth Des. 2011,
11, 4697. (b) Martinez Casado, F. J.; Ramos Riesco, M.; da Silva, I.;
Redondo Yelamos, M. I.; Labrador, A.; Rodriguez Cheda, J. A. Cryst.
Growth Des. 2011, 11, 759.
(31) Wang, X.-L.; Chen, Y.-Q.; Gao, Q.; Lin, H.-Y.; Liu, G.-C.;
Zhang, J.-X.; Tian, A.-X. Cryst. Growth Des. 2010, 10, 2174.
(32) (a) Martinez Casado, F. J.; Canadillas-Delgado, L.; Cucinotta,
F.; Guerrero-Martinez, A.; Ramos Riesco, M.; Marchese, L.; Cheda., J.
A. R. CrystEngComm 2012, 14, 2660. (b) Chen, S.-C.; Zhang, Z.-H.;
Zhou, Y.-S.; Zhou, W.-Y.; Li, Y.-Z.; He, M.-Y.; Chen, Q.; Du, M. Cryst.
Growth Des. 2011, 11, 4190. (c) Liu, X.; Guo, G.-C.; Wu, A.-Q.; Cai,
L.-Z.; Huang, J.-S. Inorg. Chem. 2005, 44, 4282.
(33) Varma, R. P.; Jain, P. K. Transition Met. Chem. 1982, 7, 129.
5348
dx.doi.org/10.1021/cg300900m | Cryst. Growth Des. 2012, 12, 5338−5348