Luminescent zinc and cadmium metal-organic frameworks based on tetrazole ligands

Article abstract of DOI:10.1016/j.poly.2009.05.015

Three metal-organic frameworks with 1D zigzag chain [Zn(dte)(H₂O)₃]·2H₂O (1), 2D double layer [Cd(dtb)(H₂O)(phen)] (2), 3D network [Zn(dte)(phen)] (3) based on tetrazole-based ligands (H₂dtb = 1,3-dis

Full text of DOI:10.1016/j.poly.2009.05.015

Polyhedron 29 (2010) 296–302
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Luminescent zinc and cadmium metal-organic frameworks
based on tetrazole ligands
a
Tuoping Hu a,b, Longjie Liu a, Xiaoli Lv a, Xiaohui Chen a, Haiyan He a, , Fangna Dai ,
*
Guoqing Zhang a, Daofeng Sun a,
*
a Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, PR China
b Department of Chemistry, North University of China, Taiyuan, Shanxi 030051, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Available online 13 May 2009
Three metal-organic frameworks with 1D zigzag chain [Zn(dte)(H2O)3]ꢀ2H2O (1), 2D double layer
[Cd(dtb)(H2O)(phen)] (2), 3D network [Zn(dte)(phen)] (3) based on tetrazole-based ligands (H2dtb =
1,3-dis(2H-tetrazol-5-yl)benzene, H2dte = 1,4-ditetrazolylethylene, phen = 1,10-phenanthroline), have
been synthesized and characterized. All the compounds exhibit unusual strong luminescence at room
temperature in the solid state and can be potentially used as luminescent materials.
Keywords:
Tetrazole
Metal-organic framework
Fluorescence
Crown Copyright Ó 2009 Published by Elsevier Ltd. All rights reserved.
1. Introduction
boxylate ligand (Scheme 1) [14–16]. The common strategy for the
construction of metal-organic frameworks with tetrazole ligands is
The design and synthesis of molecular architecture with unusual
structures and properties are now of great interest due to not only
their intriguing molecular topologies, but also their potential appli-
cations as functional materials in many fields such as gas storage,
catalysis, ion exchange, luminescence, nonlinear optics (NLO), mag-
netism [1–3]. The construction of supramolecular arrays relies on
the combination of several factors [4–5]. Thus, it is a tremendous
challenge to understand and control how these considerations
influence the crystal packing and hence build the exactly predict-
able coordination supramolecular architectures. During past dec-
ades, great progress has been made in the rational design and
controllable synthesis of such materials and a large number of com-
pounds with interesting molecular structures and excellent proper-
ties according to some basic principles and feasible experiences
have been successfully synthesized.
As an important kind of O-donor ligands, muticarboxylate li-
gands are widely used in the assembly of metal-organic frame-
works due to their various coordination modes and bridging
abilities [6–7]. Analogously, tetrazole-based ligands bearing alkyl
spacers are a splendid option of N-donor ligands, and the four
nitrogen atoms provide enough coordination sites when coordinat-
ing to metal centers with certain coordination geometries [8–13].
Previous studies show that these ligands exhibit special abilities
to formulate the compounds and induce the final structures and
topologies, and the results also indicate that tetrazole-based or-
ganic anions possess the similar coordination mode with poly-car-
based on in situ synthesis, that is, the synthesis of ligands and the
coordination between the ligands and metal ions occur simulta-
neously. Although, it is convenient to get the complexes through
one-pot hydrothermal reaction, it increases the difficulty to under-
stand the factors that influence the formation of MOFs based on
tetrazole-based ligands and survey the coordination mode of the
metal-organic complexes. Consequently, inspired by Sharpless’s
pioneering work, we synthesized two tetrazole-based ligands,
1,3-dis(2H-tetrazol-5-yl)benzene (H2dtb), 1,4-ditetrazolylethylene
(H2dte) [17–20], in which the H2dte ligand was previously synthe-
sized by Prof. Xiong through one-pot hydrothermal reaction [21].
By using above two organic ligands to assemble with metal ions,
three new metal-organic supramolecules were obtained, in which
the tetrazole groups possess similar coordination modes with car-
boxylates [21–24]. In this paper, we describe the detailed synthe-
sis, structures and luminescence properties of three compounds,
[Zn(dte)(H2O)3]ꢀ2H2O (1), [Cd(dtb)(H2O)(phen)] (2), [Zn(dte)-
(phen)] (3), which possess 1D zigzag chain, 2D (4,4) net and 3D
framework, respectively.
2. Experimental
All reagents and solvents for syntheses were purchased from
commercial sources and used as received. The tetrazole ligands
were synthesized in accordance with the procedure reported,
shown in the Scheme 2 [18,25]. Elemental analyses (C, H, N) were
obtained on a Perkin–Elmer 240 elemental analyzer. Photolumi-
nescence spectra were performed on a Perkin Elmer LS 50B lumi-
nescence spectrometer.
* Corresponding authors.
E-mail addresses: hhy_83626@163.com (H. He), dfsun@sdu.edu.cn (D. Sun).
0277-5387/$ - see front matter Crown Copyright Ó 2009 Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.05.015

T. Hu et al. / Polyhedron 29 (2010) 296–302
297
Scheme 1. Typical similar coordination modes for tetrazole ligand and carboxylate ligand.
(based on H2dte). Anal. Calc. for C20N10H12Zn: C, 47.09; N, 34.34;
H, 2.45. Found: C, 44.59; N, 33.89; H, 2.46%.
N
N
NaN3/ZnBr2
NH
N
HCl
Solids
R
CN
N
R
reflux or sealed
tubes
2.2. X-ray crystallography
N
HN
Single-crystal X-ray diffraction data for compounds 1–3 were
HN
N
N
N
recorded on a Bruker APEXII CCD diffractometer with graphite-
N
0
monochromated Mo Ka radiation (k = 0.71073 ÅA) at room temper-
N
NH
ature. All the structures were solved by Direct Method of SHELXS-97
[26] and refined by full-matrix least squares techniques using the
SHELXL-97 program [27] within WINGX [28]. The metal atoms in each
complex were located from the E-maps, and other non-hydrogen
atoms were located in successive difference Fourier syntheses
and refined with anisotropic thermal parameters on F2. The posi-
tions of H atoms were generated geometrically, assigned isotropic
thermal parameters, and allowed to ride on their parent carbon
atoms before the final cycle of refinement.
N
N
N
NH
N
N
H2dte
H2dtb
Scheme 2. The synthesis and the structures of two tetrazole ligand.
2.1. Syntheses of the metal complexes
Table 1
2.1.1. Synthesis of [Zn(dte)(H2O)3]ꢀ2H2O (1)
Crystal data and the structure refinement for complexes 1–3.
A mixture of Zn(NO3)2ꢀ6H2O (20 mg, 0.07 mmol) and H2dte
(5 mg, 0.03 mmol) was suspended in the solution of H2O (15 ml)
and boiled for 10 minutes, and then the solution of phen (10 mg,
0.06 mmol) in 5 ml MeOH was added. The mixture was filtered
and the filtrate was allowed to evaporate at room temperature
for 3 days. The yellow block crystals (6 mg) were collected, washed
with water and dried in the air. Yield: 64% (based on H2dte). Anal.
Calc. for C4H13N8O5Zn: C, 15.08; N, 35.17; H, 4.11. Found: C, 14.64;
N, 35.89; H, 3.88%.
1
2
3
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C4H11N8O5Zn C20H14CdON10 C16H10N10Zn
316.58
monoclinic
C2/c
11.496(2)
7.271(1)
15.050(3)
90.00
108.331(1)
90.00
1194.26(4)
4
1.761
2.087
644
2.85/32.25
7664
522.81
monoclinic
P2(1)/c
8.447(1)
12.221(2)
19.952(2)
90.00
94.058(1)
90.00
2054.63(5)
4
1.690
1.099
1040
1.96/27.44
4672
407.71
monoclinic
C2/c
18.729(2)
10.954(1)
7.678(1)
90.00
101.002(1)
90.00
1546.39(3)
4
1.751
1.616
824
2.16/27.47
10 365
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
2.1.2. Synthesis of [Cd(dtb)(H2O)(phen)] (2)
V (Å3)
A mixture of Cd(NO3)2ꢀ4H2O (20 mg, 0.06 mmol), H2dtb (10 mg,
0.05 mmol) and phen (10 mg, 0.06 mmol) was suspended in the
solution of H2O (15 ml), and heated in a teflon-lined steel bomb
at 150 °C for 3 days. The yellow needlelike crystals (13 mg) formed
were collected, washed with water and dried in the air. Yield: 51%
(based on H2dtb). Anal. Calc. for C20N10H14OCd: C, 45.94; N, 26.80;
H, 2.68. Found: C, 45.93; N, 26.95; H, 2.705%.
Z
q
l
calc/g cmꢁ3
(mmꢁ1
)
F(0 0 0)
h Range/deg
Number of reflections
collected
Number of independent
reflections
1770
3420
1768
Number of
0/103
0/289
0/123
2.1.3. Synthesis of [Zn(dte)(phen)] (3)
restraints/parameters
Goodness-of-fit (GOF) on F2
1.262
0.691
1.026
A mixture of Zn(NO3)2ꢀ6H2O (20 mg, 0.07 mmol), phen (10 mg,
0.06 mmol) and H2dte (5 mg, 0.03 mmol) was suspended in the
solution of H2O (15 ml), and heated in a teflon-lined steel bomb
at 140 °C for 3 days. The yellow block crystals (7 mg) formed were
collected, washed with water and dried in the air. Yield: 54%
T (K)
Rint
R1
273(2)
0.0232
0.0224
0.0704
273(2)
0.0584
0.0362
0.1580
293(2)
0.0248
0.0222
0.0628
wR2

298
T. Hu et al. / Polyhedron 29 (2010) 296–302
Table 2
zinc ion, 1 dte ligand, 1.5 coordinated water molecules and 1 unco-
Selected bond distances (Å) and angles (deg) for complexes 1–3.
ordinated water molecule (Tables 1 and 2). The central zinc ion is
five coordinated by two nitrogen atoms from different dte ligands
and three coordinated water molecules with the average Zn–N and
Zn–O distances of 2.064 and 2.053 Å, respectively. The metal envi-
ronment can be best described as a distorted tetragonal pyramidal,
with two nitrogen atoms and two coordinated water molecules
comprising the equatorial plane and one coordinated water mole-
cule occupying the axial position. The two tetrazole groups are
deprotonated during the reaction and the whole ligand acts as a
bridging linker to connect two zinc ions to result in the formation
of a one-dimensional zigzag chain structure, as shown in Fig. 1. The
nearest Zn–Zn distance in the 1D zigzag chain is 8.566 Å. The dte
ligand is almost planar with the dihedral angle between the two
tetrazole groups of 54°.
1
Zn O1 1.9833(17)
Zn N1 2.0628(12)
O1 Zn N1 106.01(3)
O1 Zn O3 95.53(5)
O1 Zn O3 95.53(5)
O3 Zn O3 168.94(10)
2
Zn N1 2.0628(12)
Zn O3 2.0833(14)
O1 Zn N1 106.01(3)
N1 Zn O3 87.19(6)
N1 Zn O3 89.76(5)
Zn O3 2.0833(14)
N1 Zn N1 147.98(6)
N1 Zn O3 89.76(5)
N1 Zn O3 87.19(6)
O Cd 2.446(4)
Cd N9 2.337(4)
Cd N6 2.289(4)
Cd N10 2.346(4)
Cd N2 2.288(4)
Cd N7 2.381(4)
N6 Cd N2 97.30(14)
N6 Cd N10 161.52(15)
N6 Cd N7 93.95(13)
N10 Cd N7 99.73(14)
N9 Cd O 94.46(13)
N6 Cd N9 96.25(16)
N2 Cd N10 96.08(14)
N2 Cd N7 85.64(14)
N6 Cd O 87.79(13)
N10 Cd O 79.76(13)
N2 Cd N9 166.14(15)
N9 Cd N10 71.42(14)
N9 Cd N7 90.51(14)
N2 Cd O 89.00(14)
N7 Cd O 174.53(12)
3
The coordinated and uncoordinated water molecules as well as
the uncoordinated nitrogen atoms of the dte ligand provide rich
hydrogen donors and acceptors, respectively. Indeed, there are
multiple supramolecular interactions existed in complex 1. The
Zn N3 2.1301(13)
Zn N5 2.1815(13)
N3 Zn N3 96.73(7)
N3 Zn N5 93.47(5)
N3 Zn N2 90.43(5)
N3 Zn N2 92.41(5)
N5 Zn N2 89.89(5)
Zn N3 2.1301(13)
Zn N2 2.2559(13)
N3 Zn N5 169.77(5)
N3 Zn N5 169.77(5)
N3 Zn N2 92.41(5)
N3 Zn N2 90.43(5)
N2 Zn N2 175.73(6)
Zn N5 2.1815(13) 2
Zn N2 2.2559(13)
N3 Zn N5 93.47(5)
N5 Zn N2 89.89(5)
N5 Zn N2 86.75(5)
N5 Zn N2 86.75(5)
p p interactions (3.360 Å) between the tetrazole rings of dte in
ꢀ ꢀ ꢀ
different zigzag chains connect the one-dimensional chains to form
a two-dimensional layer with the nearest Zn–Zn distance in adja-
cent chains of 8.840 Å, as shown in Fig. 2a. The hydrogen bonding
interactions (2.809 Å) between the coordinated water and the
uncoordinated nitrogen atom of dte ligand, as well as the strong
p p interactions (3.383 Å) between tetrazole rings in different
ꢀ ꢀ ꢀ
layers, further connect the two-dimensional layers to generate a
three-dimensional supramolecular architecture, as shown in
Fig. 2b.
3.1.2. Structure of [Cd(dtb)(H2O)(phen)] (2)
Complex 2 is a two-dimensional layer framework based on
binuclear cadmium unit. The asymmetric unit consists of one cad-
mium ion, one dtb ligand, one phen and one coordinated water
molecule (Tables 1 and 2). The cadmium atom in 2 exhibits a dis-
torted octahedral geometry (Fig. 3) with two nitrogen atoms from
phen and two nitrogen atoms from different dtb ligand comprising
the equatorial plane, while one coordinated water molecule and
one nitrogen atom from dtb ligand occupying the axial position.
The average Cd–N and Cd–O distances are 2.328 and 2.446 Å, in
agreement with other cadmium complexes [29–31].
Fig. 1. Coordination environment of the zinc ion in and view of the chains.
3. Results and discussion
3.1. Descriptions of crystal structures
The dtb ligand in 2 is almost planar with the average dihedral
angle between the central benzene ring and the side tetrazole rings
of 15.6°. The two tetrazole groups of dtb ligand possess different
3.1.1. Structure of [Zn (dte) (H2O)3]ꢀ2H2O (1)
Single-crystal X-ray diffraction reveals that complex 1 is a one-
dimensional zigzag chain with the asymmetric unit consisting of 1
Fig. 2. (a) The whole view of the zigzag chain along [1 1 0] direction, (b) view of the supramolecular architecture along [0 0 1] direction.

T. Hu et al. / Polyhedron 29 (2010) 296–302
299
nect one binuclear cadmium unit. The binuclear cadmium unit
can be considered as the basic building block of the whole frame-
work. Thus, the binuclear building blocks are infinitely connected
by the dtb ligands to generate a two-dimensional grid-like layer,
as shown in the Fig. 4a. Two coordinated phen ligands locate in
the quadrate grid by forming strong
p p interactions each other.
ꢀ ꢀ ꢀ
While the coordinated water molecules point out of the layer, pro-
viding hydrogen bonding donors. It should be noted that, if the
binuclear cadmium unit can be considered as a single node and
the dtb as a linear linker, then complex 2 has a (4,4) net, similar
to other reported complexes [32–34].
In the two-dimensional (4,4) layer, the dtb ligands connect the
cadmium ions along b-axis to generate a one-dimensional 21 left-
or right-handed helical chain with the nearest Cd–Cd distance of
11.328 Å (Fig. 4b). Thus, the two-dimensional layer can also be
considered as formed by infinitely connection of the helical chains
by sharing the binuclear cadmium unit. The left- and right-handed
21 helical chains are equal in the layer, thus, the whole structure is
achiral.
As mentioned above, the coordinated water molecules provide
the hydrogen bonding donors. The coordinated water molecules lo-
cate above or below the 2D layer and point out of the layer. Thus,
the two-dimensional grid-like layers stacked one another through
the hydrogen bonding interactions (2.871 Å) between the coordi-
nated water molecules and the uncoordinated nitrogen atoms of
dtb in different layers, giving rise to a three-dimensional supramo-
lecular architecture (Fig. 4c). The coordinated phen ligands locate
in the quadrate channels.
Fig. 3. Coordination environment of the cadmium cation in complex 2.
coordination modes: one tetrazole group adopts didentate bridging
mode to link two cadmium ions to form a binuclear unit, while the
other tetrazole group adopts monodentate bridging mode to con-
Fig. 4. (a) View of the double-layer from a axis and the highlight shows that the strong
chain and (c) view of the quadrate channels in three-dimensional supramolecular architecture (coordinated phen ligands are omitted for clarity).
pꢀ ꢀ ꢀp interactions of phen ligands, (b) one-dimensional 21 left- or right-handed helical

300
T. Hu et al. / Polyhedron 29 (2010) 296–302
Each phen acts as typical chelating ligand terminally coordinat-
ing to Zn ion with the average Zn–N distance and N–Zn–N angle
being 2.178 Å and 76.26°, respectively. The average Zn–N distance
(N from dte) is 2.194 Å, which is longer than that in 1, probably due
to the larger space hindrance from phen ligand in 3 as compared to
coordinated water molecules in 1. Both of tetrazole groups of dte
ligand are deprotonated during the reaction, and each adopts did-
entate bridging mode to connect two zinc ions. Thus, every tetra-
zole group links two zinc ions and each zinc ion attaches to four
tetrazole groups to form a one-dimensional chain, which is further
connected by the backbone of dte to generate a three-dimensional
metal-organic framework. The whole network structure can be
viewed as consisting of regular rhombus in which apexes are occu-
pied by zinc ions and the edges are formed by dte ligands (Fig. 6a).
The phen ligands coordinating to the zinc ions penetrate in the cav-
ity of the rhombus, thus the three-dimensional metal-organic
framework of 3 can also be regarded as rhombus channels filled
Fig. 5. Coordination environment of the zinc cation in complex 3.
by phen ligands which are parallel to each other through
p p
ꢀ ꢀ ꢀ
3.1.3. Structure of [Zn(dte)(phen)] (3)
interactions (3.5 Å). The dimensions of the channels are about
18.38 ꢂ 8.90 Å based on the adjacent Zn–Zn distances [22]
(Fig. 6b). The overall topology of 3 is similar with the coordination
polymer of [Mn(ta)(phen)]n based on 1,4-benzenedicarboxylic acid
ligand, which further indicates that tetrazole group possesses sim-
ilar coordination modes with the carboxylates [22].
Single-crystal X-ray diffraction studies show that complex 3 is a
three-dimensional metal-organic framework. The asymmetric unit
of 3 consists of one zinc ion, one dte ligand and one phen ligand, as
shown in Fig. 5. The central zinc ion is six-coordinated by four
nitrogen atoms from different dte ligands, two nitrogen atoms
from the chelating phen ligand (Tables 1 and 2). The coordination
geometry of the central zinc ion can be best described as a dis-
torted octahedron, where two nitrogen atoms from phen ligand
and two nitrogen atoms from different dte ligands comprise the
equatorial plane, and the other two nitrogen atoms from another
two different dte ligands occupying the axial positions with the an-
gle of axial N–Zn–N of 173.99°.
3.2. Luminescent properties
Coordination polymers are investigated for luminescence prop-
erties owing to their often higher thermal stability than the pure
organic ligand and the ability of affecting the emission wavelength
of the ligand by metal coordination. The combination of organic
Fig. 6. (a) The 3D framework of 3 from c axis, the highlights show the coordination chain between metal and the ligands from b-axis, and the
ligands, respectively; (b) view of the channels of 3 along c-axis (coordinated phen ligands are omitted for clarity).
pꢀ ꢀ ꢀp interactions of phen

T. Hu et al. / Polyhedron 29 (2010) 296–302
301
280000
240000
200000
160000
120000
80000
40000
0
40000
dte
3
1
35000
30000
25000
20000
15000
10000
5000
0
phen
2
dtb
phen
300
350
400
450
500
350
400
450
500
550
600
Wavelength(nm)
Wavelength(nm)
Fig. 7. Solid-state emission spectra of 2 at room temperature.
Fig. 8. Solid-state emission spectra of 1 and 3 at room temperature.
spacers and transition-metal centers in the coordination frame-
works can be viewed as an efficient method for obtaining new
types of luminescent materials for potential applications, e.g.
chemical sensors, photochemistry, and electroluminescent display
[35,36].
On the basis of current research of luminescent MOFs, the emis-
sion of metal-organic frameworks can be assigned to a ligand-to-
metal charge-transfer (LMCT), metal-to-ligand charge transfer
(Fig. 7). These two emission bands, 368 and 420 nm, are red-shifted
compared to free dtb or phen, and this may be ascribed to the li-
gand-to-metal charge-transfer (LMCT). Indeed, the emission band,
395 nm, is essentially unshifted from the maximum for free li-
gands, dtb and phen, which can still be assigned to intraligand
transitions.
Complex 1 based on dte shows the emission maxima at 470 nm,
while complex 3 based on dte and phen exhibits the emission max-
ima at 485 nm (Fig. 8). Both complexes 1 and 3 have a broad and
strong emission band and complex 3 has a broader one, which
may be due to the intraligands of mixed ligands in 3. In addition,
an obvious enhancement in the fluorescent intensity is observed.
The emissions that occurred in 1 and 3 can be attributed to the li-
gand-to-metal charge-transfer (LMCT).
(MLCT) or an intraligand
p ? p* transition [37]. The solid state
photoluminescent spectra of free dtb, dte and phen measured at
room temperature show the emission maxima at 396 nm for dtb,
488 nm for dte, and 388 nm for phen (Fig. 7 and 8). The emissions
of the dtb, dte and phen ligands are assigned to intraligand n ?
and * transitions.
p*
p
? p
Compared to the free ligands, the emission spectra of metal-or-
ganic frameworks of 1–3 changed. The emission band by coordina-
tion polymer 2 as compared to the emission band of the free
ligands dtb and phen is quite unexpected. A broad and strong emis-
sion in the violet-blue region with maximum at 368 and a shoulder
at 395 nm is observed as well as another weak emission at 420 nm
4. Conclusion
In this work, we have successfully synthesized three lumines-
cent metal-organic frameworks with 1D zigzag chain of 1, 2D layer
Scheme 3. The comparison of coordination modes between tetrazole ligands and carboxylate ligands.

302
T. Hu et al. / Polyhedron 29 (2010) 296–302
[8] G.-H. Cui, J.-R. Li, J.-L. Tian, X.-H. Bu, S.R. Batten, Cryst. Growth Des. 5 (2005)
1775.
[9] R.-G. Xiong, Xiang. Xue, H. Zhao, X.-Z. You, B.F. Abrahams, Z.-L. Xue, Angew.
Chem. Int. Ed. 41 (2002) 3800.
of 2, and 3D network of 3, based on tetrazole ligands of 1,3-dis
(2H-tetrazol-5-yl)benzene (H2dtb) and 1,4-ditetrazolylethylene
(H2dte). In 1 and 2, the supramolecular interactions such as hydro-
[10] L. Cheng, W.-X. Zhang, B.-H. Ye, J.-B. Lin, X.-M. Chen, Eur. J. Inorg. Chem. (2007)
gen bond and
pꢀ ꢀ ꢀp interactions play important roles in the forma-
2668.
tion of 3D supramolecular architectures. Complex 3 possesses the
similar topology with the reported [Mn(ta)(phen)]n complex based
on 1,4-benzenedicarboxylic acid, indicating the dte ligand plays
the same role with ta ligand in the formation of these complexes.
Our research shows that the tetrazole ligand possesses the similar
coordination modes (Scheme 3), and properties with the corre-
sponding carboxylate ligands in the construction of metal-organic
frameworks. The photoluminescence investigation shows that all
the coordination polymers 1–3 and corresponding free ligands
are luminescent in the solid state and can be potentially applied
as new luminescent materials.
[11] M. Dinca˘, A. Dailly, J.R. Long, Chem. Eur. J. 14 (2008) 10280.
[12] W.-L. Zhang, Y.-Y. Liu, J.-F. Ma, H. Jiang, J. Yang, Polyhedron 27 (2008) 3351.
[13] H. Park, G. Krigsfeld, S.J. Teat, J.B. Parise, Cryst. Growth Des. 7 (2007) 1343.
[14] M. Dinca˘, A.F. Yu, J.R. Long, J. Am. Chem. Soc. 128 (2006) 8904.
[15] M. Dinca˘, T.D. Harris, A.T. Iavarone, J.R. Long, J. Mol. Struct. 890 (2008) 139.
[16] C. Jiang, Z.-P. Yu, C. Jiao, S.-J. Wang, J.-M. Li, Z.-Y. Wang, Y. Cui, Eur. J. Inorg.
Chem. (2004) 4669.
[17] S.J. Wittenberger, B.G. Donner, J. Org. Chem. 58 (1993) 4139.
[18] Z.P. Demko, K.B. Sharpless, J. Org. Chem. 66 (2001) 7945.
[19] M.L. Kantam, K.B.S. Kumar, Ch. Sridhar, Adv. Synth. Catal. 347 (2005) 1212.
[20] W. Ouellette, B.S. Hudson, J. Zubieta, Inorg. Chem. 46 (2007) 4887.
[21] X.-F. Huang, Y.-M. Song, Q. Wu, Q. Ye, X.-B. Chen, R.-G. Xiong, X.-Z. You, Inorg.
Chem. Commun. 8 (2005) 58.
[22] D.-F. Sun, R. Cao, Y.-C. L, Q. Shi, W.-P. Su, M.-C. Hong, Dalton Trans. (2001)
2335.
[23] A.-L. Cheng, N. Liu, J.-Y. Zhang, E.-Q. Gao, Inorg. Chem. 46 (2007) 1034.
[24] R.-Q. Zou, L. Jiang, H. Senoh, N. Takeichi, Q. Xu, Chem. Commun. (2005) 3526.
[25] M. Dinca˘, A. Dailly, Y. Liu, C.M. Brown, D.A. Neumann, J.R. Long, J. Am. Chem.
Soc. 128 (2006) 16876.
[26] G.M. Sheldrick, SHELXS-97 Programs for X-ray Crystal Structure Solution,
University of Götingen, Götingen, Germany, 1997.
[27] G.M. Sheldrick, SHELXL-97, Programs for X-ray Crystal Structure Refinement,
University of Götingen, Götingen, Germany, 1997.
[28] L.J. Farrugia, WINGX, A Windows Program For Crystal Structure Analysis,
Supplementary data
CCDC 723831–723833 contain the supplementary crystallo-
graphic data for 1–3. These data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
University of Glasgow, Glasgow, UK, 1988.
[29] B.-H. Ye, B.-B. Ding, Y.-Q. Weng, X.-M. Chen, Cryst. Growth Des. 5 (2005) 801.
[30] X. Shi, G.-S. Zhu, Q.-R. Fang, G. Wu, G. Tian, R.-W. Wang, D.-L. Zhang, M. Xue, S.-
L. Qiu, Eur. J. Inorg. Chem. (2004) 185.
[31] Y.-Q. Lan, S.-L. Li, J.-S. Qin, D.-Y. Du, X.-L. Wang, Z.-M. Su, Q. Fu, Inorg. Chem. 47
(2008) 10600.
[32] Y.-M. Xie, J.-H. Liu, X.-Y. Wu, Z.-G. Zhao, Q.-S. Zhang, F. Wang, S.-C. Chen, C.-Z.
Lu, Cryst. Growth Des. 8 (2008) 3914.
[33] E. Yang, J. Zhang, Z.-J. Li, S. Gao, Y. Kang, Y.-B. Chen, Y.-H. Wen, Y.-G. Yao, Inorg.
Chem. 43 (2004) 6525.
[34] D. Krishna Kumar, D.A. Jose, A. Das, P. Dastidar, Inorg. Chem. 44 (2005) 6933.
[35] Q. Wu, M. Esteghamatian, N.-X. Hu, Z. Popovic, G. Enright, Y. Tao, M. D’Iorio, S.
Wang, Chem. Mater. 12 (2000) 79.
[36] J.E. McGarrah, Y.-J. Kim, M. Hissler, R. Eisenberg, Inorg. Chem. 40 (2001) 4510.
[37] G.D. Santis, L. Fabbrizzi, M. Licchelli, A. Poggi, A. Taglietti, Angew. Chem., Int.
Ed. Engl. 35 (1996) 202.
References
[1] O.M. Yaghi, C.E. Davis, H. Li, J. Am. Chem. Soc. 119 (1997) 2861.
[2] C. Janiak, J. Kim, N. Rosi, D. Vodak, J. Wachter, M. O’Keeffe, O.M. Yaghi, Dalton
Trans. (2003) 2781.
[3] K. Barthelet, J. Marrot, D. Riou, G. Férey, Angew. Chem. Int. Ed. 41 (2002) 281.
[4] M. Munakata, L.P. Wu, T. Kuroda-Sowa, M. Maekawa, K. Moriwaki, S. Kitagawa,
Inorg. Chem. 36 (1997) 5416.
[5] L. Carlucci, G. Ciani, P. Macchi, D.M. Proserpio, A. Sironi, Chem. Commun.
(1997) 631.
[6] C.N.R. Rao, S. Natarajan, R. Vaidhyanathan, Angew. Chem. Int. Ed. 43 (2004)
1466.
[7] X.-L. Wang, C. Qin, E.-B. Wang, Z.-M. Su, Chem. Eur. J. 12 (2006) 2680.