H. Yu, et al.
InorganicaChimicaActa503(2020)119426
5.8 and 8.6 Å and they have been close to the size determined by the
crystal structure.
neither dissolved in MeOH nor water, and the addition of the DMF
solvents could help to promote the solvothermal reaction. According to
the crystal data collected at room temperature, the structure of complex
1 has been decomposed together with refined. These results state
clearly that the prepared complex 1 crystallized in monoclinic space
3.3. Catalytic properties of 1a
group P21 with cell parameters as follows:
a = 9.9638(6) Å,
In view of its large window size as well as high open metal density,
we tested the activity of the synthesized framework 1 as a solid het-
erogeneous catalyst in the cyanidation of various aldehydes, i.e. using
benzaldehyde as a model substrate, after completing the above opera-
tion then using the mixture of aldehyde together with trimethylsilyl
cyanide for the cyanidation reaction, as well as a 1a in CH2Cl2 at room
temperature. As it was shown in Table 1, entry 1, with skeleton 1a as
catalyst (2 mol%), benzaldehyde has been highly converted to 2-[(tri-
methylsilyl) oxy] acetonitrile after ten hours in dichloromethane at
room temperature. When the reaction time has been further extended to
twenty-four hours, the yield of the product increased only slightly to
96%. In addition, no other else products have been tested, together with
the yield of the product has been considered to be the conversion of
benzaldehyde. With complex 1 as catalyst, the yield has been only 32%
under the same conditions. The relationship between catalytic activity
and structure is not clear in this study, however, the higher dialogue
shown by compound 1a than that shown by compound 1 may ulti-
mately be related to the one-dimensional nanochannels in its accessible
metal centers, as well as the Lewis acidity at the Co(II) site is also
higher. As it was shown in Table 1, item 8, we measured the influence
of the amount of catalyst at the same time, as well as solvent on the
cyanation reaction catalyzed by 1a. When the catalyst loading in-
creased from 1.0 mol% to 2.0 mol%, as it was shown in Table 2, Item 6
& 7, the product yield increased from 75% to 94%. However, a further
increase in load (up to 5%) only increased production by 1%. As it was
shown in Table 2, we examined the catalytic reactions in different
solvents at the same time, including MeCN, THF, CHCl3, MeOH as well
as CH2Cl2, in which CH2Cl2 (94% yield) has been the best solvent for
the conversion, together with the worst solvent has been THF (63%
yield) (Table 2, entry 7). In the absence of any catalyst, the blank test of
4-nitrobenzaldehyde has been carried out at room temperature. After
ten hours of reaction, only 12% conversion has been tested. At the same
time, the reactivity of Ni (NO3)2·6H2O as well as free ligand (H3L) in
CH2Cl2 has been also tested. The yields have been 21% together with
16% respectively.
b = 17.024(5) Å, c = 18.5358(6) Å, α = γ = 90°, β = 94.962°. The
volume of this unit cell has been 3132.1(4) Å3. This asymmetric unit of
1 has been made up of two crystallographic independent Co(II) ions, a
complete deodorization FDDI2-ligand together with three coordinated
water molecules, All these contribute to the formation of one neutral
framework. As shown in Fig. 1a, the Co(II) center is a distorted octa-
hedron with one six-coordinated structure, in which the Co-O bond
distance has been between 2.106 (4) and 2.216 (6) Å boundaries, which
are comparable with those of the Co-MOFs based on the similar organic
ligands [21,22]. As it is shown in Fig. 1b, a Co2+ metal ion has been
linked to six decarbonized carboxylic acid oxygen atoms from four
carboxylic acids. The other is a decarboxylic acid coordinated by three
water molecules together with three oxygen atoms from an independent
FDDI4- ligand. As shown in Fig. 1c, two adjacent Co2+ ions have been
bridged by carboxylic acid to form a secondary construction unit (SBUs)
of Co2(COO)4 connected to organic connectors to form a three-dimen-
sional (4,4) connection network structure with ttd-type topology. As
shown in Fig. 1c together with Fig. 1d, Co-MOF has three irregular
rectangular channels. Considering the van der Waals radius, the dia-
meter of the triangular channel along the axis is 14 × 6 Å2. It is similar
to rectangular as well as elliptical channels with aperture sizes of
4 × 8.4 Å2 together with 7 × 5 Å2, respectively, along the B together
with C axes. According to PLATON analysis, the barrier-free traffic
volume has been 2301 Å3, accounting for 71.1% of the unit traffic
volume of 3232.6 Å3.
3.2. PXRD, TGA & BET analysis
In order to check the phase purity of the prepared complex 1, the
PXRD patterns for complex 1 were collected at room temperature by
using the freshly prepared samples, and the results are shown in Fig. 2a.
The calculated together with observed diffraction peaks have been in
agreement with the purity of the sample. The difference of reflective
intensity between simulated as well as observed results has been due to
the different orientation of crystals in that powder samples. Thermal
weightlessness analysis showed that the first weightlessness rate of four
DMA molecules as well as three coordination water molecules has been
38.4% (calculated weightlessness rate has been 39.2%) in the tem-
perature range of 25–232%. After dehydration, the skeleton has been
stable below 362 °C, then decomposed after further heating. Inspired by
its appropriate pore size as well as potential porosity, we encourage
further exploration of the microporous properties of 1. As it was shown
in Fig. 2a, complex 1 has been evaluated for five hours at 313 K after
the acetone has been fully exchanged, together with the desolvent or
activated 1a has been obtained. Obviously, the characteristic peaks of
complex 1a have been basically consistent with the simulated XRD
spectra, as well as the microporous properties have been still dominant.
After removing solvent molecules from the newly established frame-
work, some displacements have been expected to be observed between
1a and 1. Furthermore, this TGA of activated 1 (1a) in the absence of
two coordination water molecules, no weightlessness will occur below
180 °C, as well as it has been stable up to 342 °C. As it was shown in
Fig. 2c, the N2 adsorption isotherm of compound 1a at 77 K reveals
shows a type I adsorption isotherm, but there is no hysteresis desorption
between the adsorptions. The adsorption quantity of N2 at 77 K together
with 1 atm achieved 412 cm3/g (Fig. 2c). The estimated apparent
Brunauer–Emmett–Teller (BET) surface area as well as Langmuir sur-
face area of 1572 together with 1731 m2/g, respectively. 1a was ana-
lyzed by using the 77 K N2 isotherm has been on the basis of the NLDFT
model which shows the size distribution of narrow holes with centers at
We also compared the activity of catalyst 1a in the reaction of other
Table 2
Optimizing the cyanidation parameters of benzaldehyde with TMSCN together
Entry
Cat
Time
Solvent
1
2
3
4
5
6
7
8
1a
1a
1
1a
1a
1a
1a
1a
2
2
2
1
5
2
2
2
–
10
24
10
10
10
10
10
10
10
12
12
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
MeCN
94
96
32
75
94
82
63
76
12
21
16
THF
CH3OH
CH2Cl2
CH2Cl2
CH2Cl2
9
10
11
–
Ni(NO3)3·6H2O
H3L
2
2
a
Reaction conditions: 4-nitrobenzaldehyde (0.50 mmol), TMSCN
(1.0 mmol), catalyst, together with solvent (2.0 mL) at room temperature.
b
Calculated by GC–MS: mol(product)/mol(aldehyde) × 100.
4