Two metal-organic frameworks (MOFs) based on binuclear and tetranuclear units: Structures, magnetism and photoluminescence

Article abstract of DOI:10.1016/j.ica.2011.11.057

Two new MOFs, [Mn(HBTC)(2-PyBim)(H₂O)] (1) and [Zn ₂(BTC)(OH)(2-PyBim)] (2) (H₃BTC = 1,3,5- benzenetricarboxylic acid, 2-PyBim = 2-(2-pyridyl)benzimidazole), have been hydrothermally synthesized and characterized by single

Full text of DOI:10.1016/j.ica.2011.11.057

Inorganica Chimica Acta 384 (2012) 170–175
Contents lists available at SciVerse ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Two metal–organic frameworks (MOFs) based on binuclear and tetranuclear
units: Structures, magnetism and photoluminescence
⇑
Fang-Hua Zhao, Yun-Xia Che, Ji-Min Zheng
Department of Chemistry, Nankai University, Tianjin 300071, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 4 July 2011
Received in revised form 23 November 2011
Accepted 24 November 2011
Available online 1 December 2011
Two new MOFs, [Mn(HBTC)(2-PyBim)(H2O)] (1) and [Zn2(BTC)(OH)(2-PyBim)] (2) (H3BTC = 1,3,5-ben-
zenetricarboxylic acid, 2-PyBim = 2-(2-pyridyl)benzimidazole), have been hydrothermally synthesized
and characterized by single-crystal X-ray diffraction (XRD), infrared spectroscopy (IR), elemental analysis
(EA). In 1, adjacent two Mn(II) ions are connected into binuclear Mn2 units which are bridged by HBTC2ꢀ
anions to generate a two-dimensional (2D) (4,4) network. In 2, the Zn(II) ions are connected into
tetranuclear Zn4 units which are bridged by the BTC3ꢀ anions to generate a 2D (3,6)-connected non-inter-
penetrating CdI2-type network with (43)2(46 ꢁ 66 ꢁ 83) topology symbol. Both 1 and 2 are extended into 3D
Keywords:
Mn2 units
Zn4 units
Magnetic property
Photoluminescent property
supramolecular structure by hydrogen bonds and
p p interactions. Magnetic studies of 1 indicate that it
ꢁ ꢁ ꢁ
exhibits ferromagnetic coupling between the binuclear Mn(II) ions, polymer 2 was found to exhibit pho-
toluminescence at about 437 nm (kex = 365 nm).
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
interactions may play important roles in the construction of its
coordination polymers. And the N–H group on imidazole ring of
In recent years, much research interest has been focused on
crystal engineering of metal–organic frameworks (MOFs) or coor-
dination polymers owing to their intriguing unusual topologies
and potential applications in many fields such as gas storage, ion
exchange, catalysis, magnetism [1,2]. Herein, the rational design
and syntheses of MOFs have received considerable interest of
many chemists. In construction of the MOFs, the selection of
appropriate organic linkers is central to determine the structures
of the resulting coordination polymers. And covalent interaction
2-PyBim can be deprotonated or neutral in crystal structures, if it
is deprotonated, the two N atoms of imidazole ring can both coor-
dinate to metal centers; if it keeps neutral, the N–H group can act
as a proton-donor to form hydrogen bonds, which also may play
important roles in the formation of complexes. And only a few
examples of transition metal coordination polymers based on
2-PyBim and polycarboxylic acid have been reported [7]. Herein,
considering all the aspects above, we report the syntheses and
structures of two new MOFs [Mn(HBTC)(2-PyBim)(H2O)] (1) and
[Zn2(BTC)(OH)(2-PyBim)] (2) based on the H3BTC and 2-PyBim
ligands. The magnetic, photoluminescent and thermogravimetric
properties of 1 and 2 have also been discussed in detail.
or supramolecular contacts (such as H-bonds and/or
pꢁ ꢁ ꢁp stacking
interactions) [3] are also important factors in preparation of MOFs.
It is well known that the carboxylate ligands play an important
role in coordination chemistry owning to their diversity of coordi-
nation modes and high structural stability, especially for the
multidentate O-donor organic polycarboxylate ligands, such as
1,4-benzenedicarboxylate and 1,3,5-benzenetricarboxylate, have
been extensively employed to construct high-dimensional struc-
tures [4]. On the other hand, the N-donor ligands such as imidaz-
ole, pyridine and their derivatives have also attracted great
attention in construction of MOFs [5]. Furthermore, many efforts
have been devoted to use of N- and O-donor organic ligands as
mixed ligands to bridge metal ions to construct MOFs [6]. As a good
2. Experimental
2.1. Materials and measurements
All chemical regents were purchased commercially and were
used as received without further purification. The C, H and N ele-
mental analyses were performed on a Perkin–Elmer 240 C H N ele-
mental analyzer. The FT-IR spectra were recorded from KBr pellets
on a Nicolet Magna-IR 560 Infrared spectrometer in the 4000–
400 cmꢀ1 region. Variable-temperature magnetic susceptibility
was measured on a Quantum Design MPMS-7 SQUID magnetome-
ter. The photoluminescence measurement was carried out on
crystalline samples at room temperature, and the spectra were
N-donor ligand, 2-PyBim (Scheme 1) has larger conjugated
p-
system than imidazole and 2,20-bipy, therefore,
pꢁ ꢁ ꢁp stacking
⇑
Corresponding author. Tel./fax: +86 022 23508056.
E-mail address: jmzheng@nankai.edu.cn (J.-M. Zheng).
collected with a Hitachi F-2500FL spectrophotometer. The
0020-1693/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2011.11.057

F.-H. Zhao et al. / Inorganica Chimica Acta 384 (2012) 170–175
171
Scheme 1. Coordination modes of H3BTC in 1 and 2, and the structure of 2-PyBim.
thermogravimetric analyses (TGA) were investigated on a standard
TG-DTA analyzer under nitrogen flow at a heating rate of 5 °C/min
Table 1
Crystal data and structure refinement for 1 and 2.
for all measurements.
Complex
1
2
Formula
C
21H15MnN3O7
C21H13N3O7Zn2
550.12
triclinic
Formula weight
Crystal system
Space group
a (Å)
b (Å)
c (Å)
476.30
monoclinic
P21/c
11.488(1)
11.014(4)
16.222(4)
90
107.22(5)
90
1960.5(11)
4
2.2. Synthesis
ꢀ
P1
2.2.1. Synthesis of [Mn(HBTC)(2-PyBim)(H2O)] (1)
10.035(1)
10.678(2)
11.189(5)
79.71(3)
66.48(3)
63.96(1)
987.7(5)
2
A mixture of H3BTC (0.105 g, 0.5 mmol), MnCl2ꢁ4H2O (0.099 g,
0.5 mmol), 2-PyBim (0.098 g, 0.5 mmol) and water (10 mL) was stir-
red for 30 min. The pH value of the mixture was adjusted to 6.0 with
1 molLꢀ1 NaOH solution, and then the resulting mixture was trans-
ferred and sealed in a 25 mL Teflon-lined stainless-steel container
and heated at 160 °C for 72 h. After slowly cooled to room tempera-
ture, the colorless single crystals of 1 were collected. Yield: 55%
based on Mn(II). Elemental Anal. Calc. for C21H15MnN3O7: C, 52.96;
H, 3.17; N, 8.82. Found: C, 52.90; H, 3.11; N, 8.84%. IR (KBr, cmꢀ1):
3403 (w), 3078 (w), 1689 (s), 1603 (m), 1561 (s), 1483 (w), 1441
(m), 1392 (w), 1340 (m), 1268 (m), 1102 (w), 1052 (w), 1007 (w),
978 (w), 797 (w), 748 (m), 683 (w), 536 (w).
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (g/cm3)
F(000)
1.614
972
1.850
552
Reflections collected
18600
0.1133
4680
2150
1.003
9727
0.0364
4645
3408
1.002
(Rint
)
Independent reflections
Observed reflections [I > 2
Goodness-of-fit on F2
r(I)]
R1 [I > 2
wR2 [I > 2
r
(I)]a
(I)]b
0.0541
0.1236
0.0485
0.1071
r
a
R1
wR2 = {
=
R
||Fo| ꢀ |Fc||/
R|Fo|.
2.2.2. Synthesis of [Zn2(BTC)(OH)(2-PyBim)] (2)
R
[w(Fo ꢀ Fc2)2]/
R .
[w(Fo2)2]}1/2
b
2
A
mixture of H3BTC (0.105 g, 0.5 mmol), Zn(NO3)2ꢁ6H2O
(0.297 g, 1 mmol), 2-PyBim (0.098 g, 0.5 mmol) and water
(10 mL) was stirred for 30 min. The pH value of the mixture was
adjusted to 6.0 with 1 molLꢀ1 NaOH solution, and then the result-
ing mixture was transferred and sealed in a 25 mL Teflon-lined
stainless-steel container and heated at 160 °C for 72 h. After slowly
cooled to room temperature, the colorless single crystals of 2 were
collected. Yield: 65% based on Zn(II). Elemental Anal. Calc. for
3. Results and discussion
3.1. Description of crystal structures
3.1.1. [Mn(HBTC)(2-PyBim)(H2O)] (1)
C
21H13N3O7Zn2: C, 45.85; H, 2.38; N, 7.64. Found: C, 45.76; H,
Single-crystal X-ray diffraction study reveals that complex 1
crystallizes in the monoclinic P21/c space group. The asymmetry
unit consists of one crystallographically independent Mn(II) ion,
one non-completely deprotonated HBTC2ꢀ anion, one neutral 2-
PyBim ligand and one coordinated water. The Mn(II) center exhib-
its a distorted octahedral coordinated environment, completed by
two 2-PyBim nitrogen atoms (Mn–N 2.219(4)–2.336(4) Å), three
carboxyl oxygen atoms (Mn–O 2.166(3)–2.180(3) Å) and one water
oxygen atom (Mn–O 2.161(3) Å) (Fig. 1a). The non-completely
deprotonated HBTC2ꢀ anion acts as a tridentate bridging spacer
2.40; N, 7.62%. IR (KBr, cmꢀ1): 3269 (w), 2859 (w), 2762 (w),
2362 (w), 1614 (s), 1564 (s), 1439 (s), 1371 (s), 1151 (w), 989
(m), 933 (w), 792 (w), 771 (m), 739 (m), 708 (s), 572 (w), 553
(m), 448 (w).
2.3. X-ray crystallography
Accurate unit cell parameters of complex 1 and 2 were deter-
mined by a least-squares fit of 2h values, and intensity data was
measured on a Rigaku r-axis rapid IP area detector with Mo K
a
linking three Mn(II) atoms with the l3
(Scheme 1, I). Two adjacent Mn(II) centers are bridged by two
2–Ocarboxyl atoms to produce the binuclear Mn2 units with the
: ,
g2 g1 coordinated mode
radiation (k = 0.71073 Å) at 113 K. The intensity was corrected for
Lorentz and polarization effects as well as for empirical absorption
based on multi-scan technique [8]. The structures were solved by
direct method and refined by full-matrix least-squares fitting on
F2 by SHELX-97 [9]. All non-hydrogen atoms were refined anisotrop-
ically, the hydrogen atoms bound to carbon atoms were calculated
theoretically and those to oxygen and nitrogen atoms were deter-
mined by different Fourier maps. Crystal data and structure refine-
ment parameters for 1 and 2 are summarized in Table 1. Selected
bond distances and angles are listed in Table S1 and those of the
hydrogen bonds are listed in Table S2.
l
Mnꢁ ꢁ ꢁMn distance of 3.46 Å and Mn–O–Mn angle of 105.15°. The
adjacent binuclear Mn2 units are further connected by HBTC2ꢀ an-
ions into a rhombic grid with the edge of 9.8 Å, which presents a
2D (4,4) network (Fig. 1b).
In the structure of 1, neutral 2-PyBim ligands occupy the void of
the (4,4) grid in pair and form the intralayer
tween the two 2-PyBim molecules and between the 2-PyBim and
HBTC2ꢀ ligands with the interplanar separation of 3.626(3),
3.399(3) and 3.806(3) Å, respectively (Table S3). Moreover, the
pꢁ ꢁ ꢁp interactions be-

172
F.-H. Zhao et al. / Inorganica Chimica Acta 384 (2012) 170–175
Fig. 1. (a) The coordination environment for Mn center in 1, symmetry code:
#1 = 1 ꢀ x, ꢀy, 1 ꢀ z; #2 = 1 ꢀ x, 0.5 + y, 1.5 ꢀ z; (b) The 2D layer structure of 1 with
(4,4) network; (c) View of the 3D supramolecular structure of 1, the blue dashed
lines stand for the hydrogen bonds.
intralayer N2–H2ꢁ ꢁ ꢁO4 (2.832(5) Å, 160.2°) hydrogen bond also ex-
ists between the 2-PyBim and HBTC2ꢀ anions. It should be noted
that the non-deprotonated carboxyl group of HBTC2ꢀ anion is
uncoordinated but acts as hydrogen-bonds donor and acceptor to
form the O5–H5ꢁ ꢁ ꢁO2 (2.592(4) Å, 173.7°) and O7–H7Bꢁ ꢁ ꢁO6
(2.738(5) Å, 160.4°) hydrogen bonds between adjacent layers.
Therefore, the 2D layers of 1 are assembled into a 3D supramolec-
ular structure (Fig. 1c). Similar 2D (4,4) network constructed by
binuclear Mn2 units was previously observed in other complexes:
[Mn(HBTC)(BIPY)(H2O)] [10a] and [Mn(HBTC)(Pyphen)(H2O)]
Fig. 2. (a) Schematic description of the Zn4 cluster of 2, symmetry code: #1 = ꢀx,
1 ꢀ y, 1 ꢀ z; (b) The 2D layer structure of 2; (c) The topological representation of the
2D layer; (d) The 3D supramolecular structure of 2, the blue dashed lines stand for
the N2–H2ꢁ ꢁ ꢁO2 hydrogen bonds.

F.-H. Zhao et al. / Inorganica Chimica Acta 384 (2012) 170–175
173
[10b]. A little difference for 1 is the additional N–Hꢁ ꢁ ꢁO hydrogen
bonds for the N–H group of imidazole ring in neutral 2-PyBim
molecule.
3.1.2. [Zn2(BTC)(OH)(2-PyBim)] (2)
ꢀ
Polymer 2 crystallizes in the triclinic P1 space group. The asym-
metry unit consists of two Zn(II) ions, one completely deproto-
nated BTC3ꢀ anion, one neutral 2-PyBim ligand and one
l3–OH
group. Both Zn(II) ions are five coordinated: Zn1 is coordinated
by three carboxylic O atoms from three different BTC3ꢀ anions
(Zn–O 1.968(2)–2.072(2) Å) and two O atoms from two
l3–OH
groups (Zn–O 2.038(3)–2.111(2) Å) to give the ZnO5 distorted
tetragonal pyramid geometry, while Zn2 is coordinated by two car-
boxylic O atoms from two different BTC3ꢀ anions (Zn–O 1.999(3)–
2.030(2) Å), one O atom from l3–OH group (Zn–O 1.952(2) Å) and
two N atoms from one neutral 2-Pybim ligand (Zn–N 2.008(4)–
2.524(4) Å) to give the ZnO3N2 distorted tetragonal pyramid geom-
etry. Furthermore, two pairs of symmetry-related Zn(II) ions are
connected by carboxylic O atoms and two
a tetranuclear Zn4 unit (Fig. 2a).
l3–OH groups to form
In 2, the completely deprotonated BTC3ꢀ ligand adopts the
l5: , ,
g2 g2 g1 coordinated mode (Scheme 1, II), and each of them
coordinates to five Zn atoms from three different Zn4 units. And
each Zn4 unit is bridged by six BTC3ꢀ anions to form a 2D layer
structure with the 2-PyBim ligands on both sides (Fig. 2b). From
a topological view, each BTC3ꢀ ligand can be regarded as a 3-con-
nected node, and the Zn4 unit is considered as a 6-connected node.
As a result, the 2D layer of 2 can be described as a (3,6)-connected
non-interpenetrating CdI2-type network with (43)2(46 ꢁ 66 ꢁ 83)
topology (Fig. 2c). The CdI2-type network was well known in inor-
ganic compounds [11], but only a few examples were found in the
metal–organic coordination frameworks [12]. Polymer 2 is a new
example for such network based on 6-connected Zn4 units.
Fig. 3. (a) Temperature dependence of magnetic susceptibility in the form of vM
(4) and
vMT (s) vs T for 1. The red solid lines are the fits of the data; (b)
Magnetization of 1; Inset: the hysteresis loop for 1 at 2 K.
Similar to 1, the 2-PyBim ligands maintain neutral and form the
p p interactions between adjacent 2-PyBim molecules with the
ꢁ ꢁ ꢁ
interplanar separation of 3.674(3), 3.580(3) and 3.705(3) Å, respec-
tively (Table S3), no interaction were found between the 2-
in study of similar binuclear Mn(II) complex [10a]. The equation
below was used to fit the magnetic susceptibility data,
pꢁ ꢁ ꢁp
PyBim and BTC3ꢀ ligands. Finally, the interlayer N2–H2ꢁ ꢁ ꢁO2
(2.739(5) Å, 166.0°) hydrogen bonds between 2-PyBim molecules
and BTC3ꢀ ligands connect the layers into a 3D supramolecular
structure (Fig. 2d). The framework of 2 is comparable to the previ-
ously reported complex of [Zn2(OH)(BTC)(Pyphen)] [13]. The (3,6)-
connected network of 2 is obviously different from (4,4) net of 1,
which may be attributed to the different coordination modes of
the non-completely deprotonated HBTC2ꢀ and completely depro-
tonated BTC3ꢀ in their structures resulting in the binuclear and tet-
ranuclear units, respectively.
Ng2b2
kT
vM ¼ ð1 ꢀ Þ ꢂ
q
e2J=kT þ 5e6J=kT þ 14e12J=kT þ 30e20J=kT þ 55e30J=kT
ꢂ
þ
1 þ 3e2J=kT þ 5e6J=kT þ 7e12J=kT þ 9e20J=kT þ 11e30J=kT
35Ng2b2
q
12kT
where N is the Avogadro number, g is the Zeeman splitting factor, b
is the Bohr magneton, J is the coupling constant, k is Boltzmann’s
constant, T is the absolute temperature,
q is the monomeric impu-
3.2. Magnetic properties
rity. The best fitting for the MT data leads to the parameter values
v
J = 1.14 cmꢀ1 and
q
= 0.3% with reasonable g factor of 1.94 [14] and
P
P
The variable-temperature magnetic susceptibility measurement
of 1 was performed in the temperature range of 2–300 K under a
R = 5.0 ꢂ 10ꢀ3 (R = [(
vMT)obs ꢀ (
v
MT)calc]2/ [(
v
MT)obs]2); and J =
P
1.22 cmꢀ1
,
q
= 0.2%, g = 1.94 and R = 2.99 ꢂ 10ꢀ4 (R = [(vM obs
)
P
field of 1000 Oe. As shown in Fig. 3a, the
v
MT value is
ꢀ (
v
)
M calc]2/ [(
v
)
M obs]2) for the vM data. The positive J value indi-
4.15 cm3 molꢀ1 K for per Mn(II) ion at room temperature, which
cates ferromagnetic coupling between Mn(II) ions. These results
indicate the spin coupling through the HBTC2ꢀ ligands can be neg-
ligible because of the long distance between adjacent Mn2 units
(9.8 Å) bridged by the HBTC2ꢀ ligands, and the main magnetic ex-
change pathway is the exchange between neighboring Mn(II) ions
is close to the expected value (4.38 cm3 molꢀ1 K) for one magne-
tism-isolated Mn(II) ion with S = 5/2 and g = 2.0. The vMT increases
continuously to 5.10 cm3 molꢀ1 K with temperature down to 34 K,
then increases sharply and finally reaches the maximum value of
7.42 cm3 molꢀ1 K at 2 K, which is characteristic of ferromagnetic
behavior. The 1/vM versus T plot at 30–300 K obeys the Curie–
via the
l2–Ocarboxyl bridge with the superexchange angle Mn–
Ocarboxyl–Mn of 105.15°, which are consistent with the similar
Weiss law
[v
M = C/(T – h)] giving Curie constant C = 4.06 cm3
example [10a].
molꢀ1 K and Weiss constant h = +9.16 K (Fig. S1). The positive value
of h further conforms the ferromagnetic coupling between Mn(II)
ions. The temperature-dependent magnetic data for 1 was mod-
eled using a Heisenberg Hamiltonian H = ꢀ2JSA ꢁ SB which was used
Further magnetic characterization of 1 was performed by field
dependent magnetization at 2 K under a magnetic field up to
50 kOe. The M values increase quickly with applied field and finally
reaches saturation value of 5.0 Nb which is excellent close to the

174
F.-H. Zhao et al. / Inorganica Chimica Acta 384 (2012) 170–175
range of 30–800 °C under nitrogen with a heating rate of 5 °C/min
(Fig. 5). Complex 1 shows a weight loss of 3.85% from 120 to
180 °C, corresponding to the loss of one coordinated water molecule
(calcd. 3.78%), and there is no weight loss from 180 to 388 °C; and
after that, a rapid weight loss is observed which is attributed to
the decomposition of the organic ligands. For complex 2, no weight
loss is observed until it reaches 323 °C, and after that, it begins to
chemically decompose. The TGA results show the number of water
molecules are consistent with the single-crystal analyses and
indicate that complex 2 is more stable than complex 1.
4. Conclusions
In this work, we have synthesized two novel metal–organic
complexes based on binuclear and tetranuclear units under hydro-
thermal condition. The results of this study illustrate that the
deprotonation of H3BTC ligand plays a central role to determine
the structures of the two complexes and the neutral 2-PyBim li-
gand also plays an important role in the construction of the com-
Fig. 4. Excitation (left) and emission (right) spectra in the solid state of 2.
plexes for the formation of N–Hꢁ ꢁ ꢁO hydrogen bonds and
p p
ꢁ ꢁ ꢁ
interactions. In addition, the magnetic analyses of 1 display ferro-
magnetic coupling within the binuclear Mn2 units, and 2 shows
photoluminescent property at room temperature.
Acknowledgements
This work was supported by the National Natural Science Foun-
dation of China under Project 50872057.
Appendix A. Supplementary Material
CCDC 807199 and 801999 contain the supplementary crystallo-
graphic data for complexes 1 and 2, respectively. These data can be
obtained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif. Supplementary
data associated with this article can be found, in the online version,
at doi:10.1016/j.ica.2011.11.057.
Fig. 5. The TGA diagram of 1 (black line) and 2 (red line). (For interpretation of the
references to colour in this figure legend, the reader is referred to the web version of
this article.)
References
expected saturation value of one Mn(II) ion (Fig. 3b), indicating
that the ground spin state of the system is the ferromagnetic one
[10a]. No magnetic hysteresis loop but a marked s-shaped curve
was observed at 2 K (Inset of Fig. 3b), indicating a typical of soft
ferromagnet for 1.
[1] (a) O.M. Yaghi, H. Li, C. Davis, D. Richardson, T.L. Groy, Acc. Chem. Res. 31
(1998) 474;
(b) M.J. Zaworotko, Angew. Chem., Int. Ed. 39 (2000) 3052;
(c) S.A. Barnett, N.R. Champness, Coord. Chem. Rev. 246 (2003) 145;
(d) S. Kitagawa, R. Kitaura, S.I. Noro, Angew. Chem., Int. Ed. 43 (2004) 2334;
(e) B.H. Ye, M.L. Tong, X.M. Chen, Coord. Chem. Rev. 249 (2005) 545;
(f) J.P. Zhang, X.M. Chen, J. Am. Chem. Soc. 131 (2009) 5516;
(g) Y.F. Zeng, X. Hu, F.C. Liu, X.H. Bu, Chem. Soc. Rev. 38 (2009) 469.
[2] (a) C. Janiak, Dalton Trans. (2003) 2781;
3.3. Photoluminescent property
(b) C. Janiak, J.K. Vieth, New J. Chem. 34 (2010) 2366;
(c) S.K. Henninger, H.A. Habib, C. Jania, J. Am. Chem. Soc. 131 (2009) 2776;
(d) J. Ehrenmann, S.K. Henninger, C. Janiak, Eur. J. Inorg. Chem. (2011) 471;
(e) U. Mueller, M. Schubert, F. Teich, H. Puetter, K. Schierle-Arndt, J. Pastré, J.
Mater. Chem. 16 (2006) 626.
Photoluminescence experiments for Zn-containing polymer 2,
as a typical d10 transition-metal configuration which exhibits pho-
toluminescent property [15,16], were performed at room temper-
ature in the solid state. As shown in Fig. 4, complex 2 displays
the emission maxima at 437 nm when excited at 365 nm, which
is similar to that observed in other Zn(II) complexes [17]. Accord-
ing to the literature, the free H3BTC ligand shows an emission band
at 380 nm (kex = 334 nm) [18], the 2-PyBim ligand shows an emis-
sion band at 369 nm [19], thus, the red shift of ca. 57 and 68 nm for
2 relative to the free H3BTC and 2-PyBim ligands could be assigned
to ligand-to-metal charge-transfer (LMCT) [20].
[3] (a) G.R. Desiraju, Angew. Chem., Int. Ed. 35 (1995) 2311;;
(b) C. Janiak, J. Chem. Soc., Dalton Trans. (2000) 3885;;
(c) V. Russel, M.L. Scudder, I.G. Dance, J. Chem. Soc., Dalton Trans. (2001) 789;;
(d) L. Pan, H. Liu, X. Lei, X. Huang, D.H. Olson, N.J. Turro, J. Li, Angew. Chem., Int.
Ed. 42 (2003) 542;;
(e) M. Nishio, CrystEngComm 6 (2004) 130;;
(f) W. Wei, M.Y. Wu, Q. Gao, Q.F. Zhang, Y.G. Huang, F.L. Jiang, M.C. Hong, Inorg.
Chem. 48 (2009) 420.
[4] (a) S.M-F. Lo, S.S-Y. Chui, L.Y. Shek, Z.Y. Lin, X.X. Zhang, G.H. Wen, I.D. Williams,
J. Am. Chem. Soc. 122 (2000) 6293;;
(b) A.C. Sudik, A.P. Co te, O.M. Yaghi, Inorg. Chem. 44 (2005) 2998;;
(c) C. Serre, C.M. Draznieks, S. Surblé, N. Audebrand, Y. Filinchuk, G. Férey,
Science 315 (2007) 1828;;
(d) W.X. Chen, S.T. Wu, L.S. Long, R.B. Huang, L.S. Zheng, Cryst. Growth Des. 7
(2007) 1171;;
3.4. Thermogravimetric analyses
(e) L.G. Qiu, Z.Q. Li, Y. Wu, W. Wang, T. Xu, X. Jiang, Chem. Commun. (2008)
3642;;
To estimate the thermostability of complexes 1 and 2, thermo-
gravimetric analyses (TGA) were carried out in the temperature
(f) J.W. Yoon, Y.K. Seo, Y.K. Hwang, J.S. Chang, H. Leclerc, S. Wuttke, P. Bazin, A.

F.-H. Zhao et al. / Inorganica Chimica Acta 384 (2012) 170–175
175
Vimont, M. Daturi, E. Bloch, P.L. Llewellyn, C. Serre, P. Horcajada, J.M. Grenche,
A.E. Rodrigues, G. Férey, Angew. Chem., Int. Ed. 49 (2010) 1.
[5] (a) Q.D. Liu, W.L. Jia, S. Wang, Inorg. Chem. 44 (2005) 1332;;
(b) Y. Qi, F. Luo, Y.X. Che, J.M. Zheng, Cryst. Growth Des. 8 (2008) 606;
(c) F.J-B. Dominique, H. Gornitzka, A.S. Saquet, C. Hemmert, J. Chem. Soc.,
Dalton Trans. (2009) 340.
[6] (a) C.B. Aakeröy, N.R. Champness, C. Janiak, CrystEngComm 12 (2010) 22;;
(b) H.A. Habib, J. Sanchiz, C. Janiak, Inorg. Chim. Acta. 362 (2009) 2452;;
(c) H.A. Habib, A. Hoffmann, H.A. Höppe, C. Janiak, Dalton Trans. (2009) 1742;
(d) B. Wisser, Y. Lu, C. Janiak, Z. Anorg. Allg. Chem. 633 (2007) 1189.
[7] (a) C.K. Xia, C.Z. Lu, D.Q. Yuan, Q.Z. Zhang, X.Y. Wu, J.J. Zhang, D.M. Wu, J. Mol.
Struct. 831 (2007) 195;;
(b) B. Yan, C.S. Day, A. Lachgar, Chem. Commun. (2004) 2390;;
(c) E.Y. Choi, P.M. Barron, R.W. Novotney, C. Hu, Y.U. Kwon, W. Choe,
CrystEngComm 10 (2008) 824;;
(d) Z.B. Han, G.X. Zhang, M.H. Zeng, D.Q. Yuan, Q.R. Fang, J.R. Li, J. Ribas, H.C.
Zhou, Inorg. Chem. 49 (2010) 769;
(e) Y.Q. Zheng, X.X. Guo, X.Y. Han, J.H. Xu, Inorg. Chim. Acta. 371 (2011) 36.
[13] Y.Q. Wang, R. Cao, D.F. Sun, W.H. Bi, X. Li, X.J. Li, J. Mol. Struct. 657 (2003) 301.
[14] T. Matsumoto, T. Shiga, M. Noguchi, T. Onuki, G.N. Newton, N. Hoshino, M.
Nakano, H. Oshio, Inorg. Chem. 49 (2010) 368.
[15] (a) H.A. Habib, J. Sanchiz, C. Janiak, Dalton Trans. 1 (2008) 1734;;
(b) S. Zang, Y. Su, Y.Z. Li, J. Lin, X. Duan, Q. Meng, S. Gao, CrystEngComm 11
(2009) 122;;
(b) L.J. Zhou, Y.Y. Wang, C.H. Zhou, C.J. Wang, Q.Z. Shi, S.M. Peng, Cryst. Growth
Des. 7 (2007) 300;;
(c) P. Ren, M.L. Liu, J. Zhang, W. Shi, P. Cheng, D.Z. Liao, S.P. Yan, Dalton Trans.
(2008) 4711;
(c) W. Li, M.X. Li, J.J. Yang, M. Shao, H.J. Liu, J. Coord. Chem. 61 (2008) 2715;
(d) J. Li, C.C. Ji, L.F. Huang, Y.Z. Li, H.G. Zheng, Inorg. Chim. Acta. 371 (2011) 27.
[8] CrystalClear, version 1.3.5., Rigaku Corp., Woodlands, TX, (1999).
[9] G.M. Sheldrick, SHELXL-97: Programs for X-ray Crystal Structure Refinement;
University of Göttingen: Germany, (1997).
(d) W. Liu, Li. Ye, X. Liu, L. Yuan, J. Jiang, C. Yan, CrystEngComm 10 (2008)
1395;
(e) S.L. Zheng, X.M. Chen, Aust. J. Chem. 57 (2004) 703.
[16] M.D. Allendorf, C.A. Bauer, R.K. Bhakta, R.J.T. Houk, Chem. Soc. Rev. 38 (2009)
1330.
[10] (a) M. John Plater, M.R.St.J. Foreman, E. Coronado, C.J. Gómez-García, A.M.Z.
Slawin, J. Chem. Soc., Dalton Trans. (1999) 4209;
[17] (a) X.Q. Liang, X.H. Zhou, C. Chen, H.P. Xiao, Y.Z. Li, J.L. Zuo, X.Z. You, Cryst.
Growth Des. 9 (2009) 1041;;
(b) G.B. Che, C.B. Liu, B. Liu, Q.W. Wang, Z.L. Xu, CrystEngComm 10 (2008) 184.
[11] (a) C.G. Subhash, A.M. Michael, Y.C. Michael, E.B. William, J. Am. Chem. Soc.
113 (1991) 1844;
(b) Z.W. Wang, C.C. Ji, J. Li, Z.J. Guo, Y.Z. Li, H.G. Zheng, Cryst. Growth Des. 9
(2009) 475.
[18] J. Yang, Q. Yue, G.D. Li, J.J. Cao, G.H. Li, J.S. Chen, Inorg. Chem. 45 (2006) 2857.
[19] S.M. Yue, H.B. Xu, J.F. Ma, Z.M. Su, Y.H. Kan, H.J. Zhang, Polyhedron 25 (2006)
635.
(b) M.P. Annika, L.G. Westinand, K.Chem. Mikael, Chem. Eur. J. 7 (2001) 3439;;
(c) D. Thomas, E. Michel, M.L. Yves, A.S.C. Pascale, F. Marcand, B. Patrick, J. Am.
Chem. Soc. 125 (2003) 3295.
[20] (a) J.C. Dai, X.T. Wu, Z.Y. Fu, C.P. Cui, S.M. Hu, W.X. Du, L.M. Wu, H.H. Zhang,
R.O. Sun, Inorg. Chem. 41 (2002) 1391;
[12] (a) N. Snejko, C. Cascales, B. Gomez-Lor, E. Gutierrez-Puebla, M. Iglesias, C.
Ruiz-Valero, M. Angeles Monge, Chem. Commun. (2002) 1366;;
(b) A. Thirumurugan, S. Natarajan, J. Chem. Soc., Dalton Trans. (2004) 2923.