H. Zhang et al. / Journal of Solid State Chemistry 217 (2014) 22–30
23
based assemblies. On the one hand, they can always act as reducing
2.2.2. Preparation of (Hbbi)
2
(H
(HPO
Compound 2 was prepared similar to the method of compound
1, except that the initial chemicals Cu(NO O were substi-
ꢀ 3H
tuted by Ni(NO O (0.564 g, 2.21 mmol). Dark red block
2
bbi)
VI
V
V
agents to reduce Mo into Mo centers. On the other hand, they can
induce the {P Mo }-based inorganic fragments to form different
dimensions or various packing arrangements in the final hybrid
materials via hydrogen bonding, stacking and weak Van der
[Ni
3
Mo12
O
24(OH)
6
(H
2
O)
2
4
)
4
(H PO
2
4
)
2
ꢀ (PO
4
)
2
] ꢀ 9H
2
O (2)
4
6
3
)
2
2
π
–
π
3
)
2
ꢀ 4H
2
Waals force. Sometimes, the breaking and oxidation cracking reaction
for C–C bond of some flexible ligand was observed, that is, organic
ligands was transformed into new ligand via certain in situ reaction. It
provides an opportunity to generate organic ligands that are difficult
to be synthesized in a conventional method. Thus, it could make a
significant contribution to design and synthesize various novel POM-
based hybrid assemblies.
crystals of 2 were isolated. The crystalline products were collected
by filtration, washed with distilled water, and air-dried to give a
yield of 47% (based on Mo). Elemental anal. Calculated values (%)
for C30
H61Mo12
N
12Ni
3
O P
73 8
(Mr¼3333.02) (%): C, 10.81; H, 1.84; N,
5.04; P, 7.43; Mo, 34.54; Ni, 5.28; Experimental (%): C, 10.85; H,
1.80; N, 5.09; P, 7.39; Mo, 34.51, Ni, 5.31
Based on aforementioned considerations, we introduce nickel
2
.2.3. Preparation of (Hbpy)(bpy)
3
[Ni
] ꢀ 6H
Compound 3 was prepared similar to the method of compound 2,
2
(H
2 2
O)10Na(PCA) ]
V
(
II) and copper(II) cation as linkers into the {P
hydrothermal conditions via changing the ligand to synthesize
three new supramolecular assemblies based on {P Mo } cluster,
(HPO
24(OH) (H
[Ni (H
O (3). Our result further
4 6
Mo } system under
[NiMo12
O
24(OH)
6
ꢀ (H
2
PO
4
)
6
(PO
4
)
2
2
O (3)
4
6
except that the initial chemicals bbi were substituted by bpp (0.512 g,
V
namely, (Hbbi)
2
(H
O (1), (Hbbi)
(PO
] ꢀ 9H
24(OH) (H PO
2
bbi)[Cu
3
Mo12
O
24(OH)
6
(H
O
2
O)
6
4
)
4
(H
2
PO
4
)
)
2
0
2.58 mmol) and 4,4 -bipyridine, (0.425 g, 2.72 mmol). Dark red block
V
(
(
[
PO
4
)
2
] ꢀ 3H
2
2
(H
2
bbi)[Ni
3
Mo12
6
2
O) (HPO
2
4
4
crystals of 3 were isolated. The crystalline products were collected by
filtration, washed with distilled water, and air-dried to give a yield of
H
2
PO
4
)
2
4
)
2
2
O
(2), (Hbpy)(bpy)
(PO
] ꢀ 6H
3
2
2 2
O)10Na(PCA) ]
V
NiMo12
O
6
2
4
)
6
4
)
2
2
4
H
6
3% (based on Mo). Elemental anal. Calculated values (%) for C52
10Na Ni
(Mr¼3747.30) (%): C, 16.67; H, 1.94; N, 3.74; P,
.61; Mo, 30.72, Na, 0.62, Ni, 4.70; Experimental (%): C, 16.71; H, 1.90;
N, 3.78; P, 6.56; Mo, 30.76; Na, 0.69, Ni, 4.64.
suggests that organonitrogen ligands is an excellent template
72Mo12
N
3 82 8
O P
reagent and linker unit to induce new {P
cular assemblies.
4 6
Mo }-based supramole-
2.3. Preparation of 1-, 2-, and 3-CPEs
2
. Experimental
Complexes 1, 2, and 3 modified carbon paste electrodes (1-, 2-,
2
.1. Materials and general procedures
and 3-CPEs) were prepared as follows: 300 mg of graphite powder
and 30 mg of complex were mixed and ground together by agate
mortar and pestle to achieve a uniform mixture. To the mixture,
three drops of nujol were added with stirring. The homogenized
mixture was used to pack into a glass tube with 3 mm inner
diameter, and the surface was pressed tightly onto weighing paper
with a copper rod through the back. Electrical contact was
established with a copper rod through the back of the electrode.
All chemicals purchased were of reagent grade and used without
further purification. Elemental analyses (C, H, N) were performed on a
Perkin-Elmer 2400 CHN elemental analyzer. Mo, P, Cu, Na, and Ni were
determined with a Leaman inductively coupled plasma (ICP) spectro-
meter. IR spectra were recorded in the range 400–4000 cm
Alpha Centaurt FT/IR spectrophotometer with the pressed KBr pellets.
Diffuse reflectance UV–vis spectra (BaSO pellets) were obtained with
ꢁ
1
on a
4
a Varian Cary 500 UV–vis NIR spectrometer. XRD patterns were
collected on a Rigaku Dmax 2000 X-ray diffractometer with graphite
2.4. X-ray crystallography
monochromatized CuK
α
radiation (
λ
¼0.154 nm) and 2
θ ranging from
The crystal data of 1, 2, and 3 were collected on a Bruker
5
to 501. TG analyses were performed on a Perkin-Elmer TGA7
SMART CCD diffractometer with MoK
93 K. The structures were solved by the direct methods and
α
radiation (λ¼0.71073 Å) at
ꢁ
1
instrument in flowing N
2
with a heating rate of 10 1C min . The
2
electrochemical measurement was carried out on a CHI 660 electro-
chemical workstation at room temperature (25–30 1C). A conventional
three- electrode system was used. The working electrode was a carbon
paste electrode (CPE), a Pt wire as the counter electrode and Ag/AgCl
2
refined by the full-matrix least-squares method on F with the
SHELXTL 97 crystallographic software package [36,37]. Anisotropic
thermal parameters were used to refine non-hydrogen atoms.
Hydrogen atoms on C and N atoms of the organic ligands were
included in their calculated positions. Hydrogen atoms attached to
lattice water molecules were found from the difference Fourier
maps. Crystallographic data for the structural analysis have been
deposited with the Cambridge Crystallographic Data Center (CCDC
no. 980058 for compound 1, 980059 for compound 2, and 980060
for compound 3). A summary of crystal data and structure
refinement for compounds 1, 2, and 3 is provided in Table 1.
Selected bond lengths and angles 1, 2, and 3 are listed in Table S1.
(
3 M KCl) electrode was used as a reference electrode. Magnetic
susceptibility data were collected over the temperature range of 2–
00 K in a magnetic field of 10 kOe on a Quantum Design MPMS-5
SQUID magnetometer.
3
2
2
.2. Synthesis
.2.1. Preparation of (Hbbi)
2
(H
2
bbi)
(H
ꢀ 2H
V
[Cu
3
Mo12
O
24(OH)
6
(H
2
O)
6
(HPO
4
)
4
2
PO
O (1.252 g, 5.17 mmol), Cu
PO
ꢀ (2 mL, 30 mmol), bbi
O (18 mL, 1.0 mol) was stirred for half
4
)
2
(PO
4
)
2
2
] ꢀ 3H O (1)
The mixture of Na
NO
ꢀ 3H
0.382 g, 2.36 mmol), and H
2
MoO
4
2
(
(
3
)
2
2
O (0.516 g, 2.14 mmol), H
3
4
3. Results and discussion
2
an hour and adjusted with 1 M NaOH solution to pH¼3.5. Then,
the above mixture was sealed in a 25-mL Teflon reactor and
heated at 165 1C for 5 days. Dark red block crystals of 1 were
isolated. The crystalline products were collected by filtration,
washed with distilled water, and air-dried to give a yield of 46%
3.1. Synthesis
During our exploration on the new [P
4 6
Mo ]-based supramole-
cular assembly, we are interested in employing transition metal
2
þ
2þ
Ni
and Cu
Mo
cation as the possible linkage unit to induce
]-based materials. Complexes 1–3 were achieved
(
based on Mo). Elemental anal. Calculated values (%) for
(3311.57): C, 10.88; H, 1.74; N, 5.08; P,
.48; Mo, 34.77; Cu, 5.76. Experimental: C, 10.83; H, 1.70; N, 5.12; P,
.53; Mo, 34.72; Cu, 5.82.
different [P
4
6
C
30
H
57Cu
3
Mo12
N
12
O
71
P
8
by changing organic ligands and metal cations under the similar
reaction temperature and time. The self-assembly reactions of
7
7
Na
2
MoO
4
ꢀ 2H
2
O, H
3
PO
4
, TM(NO
3
)
2
(TM¼Cu and Ni), H
2
O, and bbi