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J. Xia et al. / Inorganica Chimica Acta 411 (2014) 35–39
purchased from Sinopharm Chemical Reagent Co., Ltd. Trim-
ethylsilylcyanide was purchased from Alfa. Other reagents were
purchased from Beijing chemical agent company. Powder X-ray
diffraction (PXRD) data were obtained using SHIMADAZU XRD-
3. Results and discussion
3.1. Synthesis
6000 diffractometer with Cu Ka radiation (k = 1.5418 Å), with the
Solvothermal synthesis method is widely used in the syntheses
of coordination polymers and solvents show a remarkable influ-
ence on the terminal structures of coordination polymers.
In(OH)(H2O)(1,4-bdc) was synthesized at a relatively low reaction
temperature in mixed DMF/CH3CN solvents. When single DMF or
CH3CN was used to replace mixed solvents for In(OH)(H2O)(1,4-
bdc) under the same condition, the same phases were not obtained
which can be attributed to different polarity and solubility of sol-
vents. It is found that no phosphotungstic acid was incorporated
into the resulting framework of In(OH)(H2O)(1,4-bdc). Moreover,
the products could not be obtained from a solution in absence of
12-phosphotungstic acid. In addition, In(OH)(H2O)(1,4-bdc) could
not be obtained at the same pH range adjusted by other inorganic
acids. This demonstrates that the heteropolyacid additive plays the
role of structure-directing agent and pH adjusting agent in the
reaction process.
step size and the count time of 0.02° and 4 s, respectively. The ele-
mental analysis was conducted on a Perkin Elmer 2400 elemental
analyzer. FT-IR spectrum was recorded on a Nicolet Impact 410
spectrometer between 400 and 4000 cmꢁ1 using the KBr pellet
method. Thermogravimetric analysis (TGA) was conducted on a
Perkin-Elmer TGA 7 thermogravimetric analyzer with a heating
rate of 10 °C minꢁ1 from room temperature to 800 °C. 1H NMR
spectra were measured on a Bruker Avance 300 console at a fre-
quency of 300 MHz.
2.2. Synthesis
A mixture of 1,4-H2bdc (0.03 g, 0.18 mmol), InCl3ꢀ4H2O (0.05 g,
0.17 mmol), and H3PW12O40ꢀnH2O (0.01 g) were added to 1 ml
N,N0-dimethylformamide (DMF) and 5 ml acetonitrile (CH3CN) in
a 23 ml Teflon-lined stainless steel vessel autoclave. The mixture
was sealed and heated at 120 °C for 4 days. The colourless block
crystals were obtained by filtration and washed by DMF several
times. The yield of product was 70% in weight based on indium.
The elemental analysis results are listed as follows: Anal. Calc. for
In(OH)(H2O)(1,4-bdc): C, 30.61; H, 2.25. Found: C, 30.50; H,
2.16%. IR (KBr pellet, cmꢁ1): 3442 (br, m), 2965 (w), 2916 (w),
2058 (w), 1574 (s), 1505(w), 1422 (m), 1160 (s), 1062 (s), 945
(s), 855 (s), 772 (w), 744 (w), 551 (s), 467 (w).
3.2. Characterization
The phase purity of In(OH)(H2O)(1,4-bdc) was confirmed by
PXRD measurement and PXRD pattern of the as-synthesized sam-
ple is very consistent with the simulated one (Fig. 1). The differ-
ences in intensity may be owing to the preferred orientation of
the powder samples.
Thermogravimetric analysis (TGA) of In(OH)(H2O)(1,4-bdc) was
conducted under air atmosphere in range from 25 to 800 °C to
determine its thermal stability which is deemed an important
property for coordination polymers [26]. As shown in Fig. S1,
In(OH)(H2O)(1,4-bdc) partially loses the lattice water from 120 to
300 °C and then decomposes rapidly. The weight loss of 61.2% is
in agreement with the decomposition of In(OH)(H2O)(1,4-bdc) to
InO1.5 (calcd 61.4%). The residue at 800 °C is identified to be
In2O3 by PXRD measurement.
2.3. Crystal structure determination
The crystallographic data for In(OH)(H2O)(1,4-bdc) were
collected on a Siemens Smart CCD diffractometer with graphite-
monochromated Mo Ka (k = 0.71073 Å) radiation at a temperature
of 293(2) K. No significant decay was observed during the data col-
lection. Data processing was accomplished with the RAPID AUTO pro-
cessing program. The structure was solved by direct method and
refined by full-matrix least-squares on F2 using the SHELXTL crystal-
lographic software package [23,24]. All indium atoms were located
first, and then the oxygen and carbon atoms were subsequently
found in difference Fourier maps. All non-hydrogen atoms were re-
fined anisotropically. The hydrogen atoms of ligands were gener-
ated geometrically.
3.3. Structural description
In(OH)(H2O)(1,4-bdc) crystallizes in the orthorhombic Pnma
space group, there are one In(III) ion and one 1,4-bdc ligand in
the asymmetric unit. As shown in Fig. 2, the In In(III) ion is
2.4. Catalytic experiment
Activation of the catalysts was performed by freeze-drying meth-
od [25]: after washing with MeOH and CH2Cl2, the resultant sample
was further washed with benzene several times. The suspension of
the sample in benzene was then frozen at 0 °C. After three freeze–
thaw cycles, the sample cell was placed under dynamic vacuum in
an ice/H2O bath for 24 h. The ice/H2O bath was removed and the
sample was kept under vacuum at room temperature for another
24 h, and then heated under vacuum at 60 °C for 16 h.
A typical cyanosilylation procedure was performed as follows: a
quantity of 40 mg (0.12 mmol) of activated catalyst was suspended
in dry acetonitrile (5 ml) followed by the addition of the aldehyde
or ketone (0.5 mmol) and trimethylsilylcyanide (1.2 mmol). The
reaction mixtures were stirred at room temperature under N2.
The yields of the reactions were determined by 1H NMR spectros-
copy and were calculated based on the carbonyl substrate. Cata-
lytic recyclability was checked for three times with the same
batch of catalyst, and no obvious decrease in activity was observed.
The observed yields in three consecutive runs were 100%, 97%, and
98%, respectively.
Fig. 1. The simulated and experimental powder X-ray diffraction patterns for
In(OH)(H2O)(1,4-bdc).