Highly effective Br?nsted base/lewis acid cooperative catalysis: A new Cd metal-organic framework for the synthesis of Hantzsch 1,4-DHPs at ambient temperature

Article abstract of DOI:10.1039/c7nj01509g

A new 3D metal-organic framework {[Cd₃(BDC)₃(OPP)(DMF)₂]·2DMA}_n (TMU-33) has been synthesized using a novel V-shaped imine-functionalized ligand, N,N′-(oxybis(4,1-phenylene))bis(1-(pyridin-4-yl)methanimine) (OPP), terephthalic acid (H₂BDC), and Cd(NO₃)₂·4H₂O and has been fully characterized. The function of the imine moiety of the OPP ligand as a Br?nsted base and open Cd site as a Lewis acid in this framework was investigated to determine the role of the cooperative catalyst in the synthesis of Hantzsch 1,4-dihydropyridines simultaneously and separately at ambient temperature. In addition, nanorods and nanoplates of TMU-33 were synthesized via a sonochemical reaction by the coordination modulation method, and the effect of the nanostructure on the relative accessibility of the catalytic site was studied. Moreover, the catalytic performance of TMU-33 with different morphologies was evaluated in this reaction. Efficient catalytic activity was observed for the nanoscale catalysts at ambient temperature, and the acidic sites in the cooperative catalyst were found to be more effective than the existing basic sites in the structure. TMU-33 can be reused by washing with ethanol at least four times with no significant degradation of the catalytic activity (less than 7%).

Full text of DOI:10.1039/c7nj01509g

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Highly Effective Brønsted Base/Lewis Acid Cooperative Catalysis: A new Cd
metal-organic framework for synthesis of Hantzsch 1, 4-DHPs at ambient
temperature
*
Farzaneh Rouhani and Ali Morsali
Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14115-
175, Tehran, Iran
*
To whom correspondence should be addressed, E-mail: morsali_a@modares.ac.ir
Tel: +98 21 82884416, Fax: +98 21 82884416
1

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Abstract
A new 3D metal-organic framework {[Cd (BDC) (OPP)(DMF) ].2DMA} (TMU-33) has been
n
3
3
2
synthesized by using a novel V-shaped imine functionalized ligand N,N'-(oxybis(4,1-
phenylene))bis(1-(pyridin-4-yl)methanimine) (OPP), therphtalic acid (H BDC), Cd(NO ) .4H O
2
3 2
2
and was full characterized. Operation of imine function of OPP ligand as a Brønsted base and
open Cd site as a Lewis acid in this framework was investigated in the role of cooperative
catalyst for synthesis of Hantzsch 1,4-dihydropyridines simultaneously and separately at ambient
temperature. In addition, nanorods and nanoplates of TMU-33 via sonochemical reaction were
synthesized by the coordination modulation method and its effect on the relative access of each
catalytic sites was studied. Also, catalytic performance of different morphologies of TMU-33 in
this reaction was evaluated. High and fast catalytic activity is observed in nanoscale catalysts at
ambient temperature and the acidic sites in this cooperative catalyst are more effective than the
existing base in the structure. TMU-33 can be reused by washing with ethanol for at least four
times without significant degradation of catalytic activity (less than 7%).
Keywords: MOF, cooperative catalyst, Hantzsch reaction, 1,4-Dihydropyridines
2

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1. Introduction
The using of metal-organic frameworks (MOFs) as heterogeneous catalyst is one of the first
1
applications that proposed for these porous materials , as well as one of the first performed
2
applications . These crystalline hybrid materials that constructed of metal nodes and organic
ligands become one of the attractive family of porous materials not only for porosity and
relatively large surface area of them but also for tunable features obtained through their targeted
preparation by intelligently designing of organic linkers, in addition to choose the metal ions
3
,4
with different coordination geometry for special targets . Since all MOFs have three different
parts: (i) the metal node (ii) the organic ligand (iii) the pore system, one could say that MOFs
5
,6
serve as catalyst in three different manners; (a) unsaturated metal site as Lewis acid
(b)
reactive functional group on organic ligand or further functionalization of ligands by a
7
postsynthesis treatment (c) introducing catalytic sites into pore system
,8
9,10
. However, in spite
of potentially appropriate properties and high metal contents of MOFs, their use as catalyst has
been limited to the present time. This may be due to two major flaws of these porous compounds
1
1-13
:
(i) the stability of this compounds is lower compared with that of inorganic crystalline
porous counterparts such as zeolites; and (ii) the lack of accessible active sites in many known
metal-organic frameworks; because of the coordination sphere around the metal ion is
completely occupied by the organic linkers.
1
First 1,4-dihydropyridines (1,4-DHPs) were obtained by Hantzsch and Biginelli
4
15
about a
hundred years ago which are the analogues of NADH coenzymes. They have emerged as one of
1
6,17
the most important classes of drugs for cardiovascular diseases
. This one-pot acid-catalyzed
condensation reaction includes an aldehyde with ethyl acetoacetate and ammonia or NH OAc
4
1
8-24
either in acetic acid or refluxing in alcohol
. However, the yields of 1,4-DHPs achieved by the
3

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25
Hantzsch method are generally low. A variety of Lewis acids catalysts, such as BF .OEt2
3
,
2
6-28
29
, BiCl3 , InBr3
30,31
32
, InCl3 , I2
33,34
35
36
37
, FeCl3 , TMSCl , LiClO , Bi(OTf)2
38,39
ZrCl4
,
4
4
0
41,42
43
Cu(OTf)2
and others
,also some modified methods
under improved conditions have
been applied for synthesis of these compounds. However, many of these processes suffer major
or minor limitations, such as poor selectivity, low yield, using of organic solvents, drastic
reaction conditions, the applications of expensive reagents, various side products, unsatisfactory
yields, long reaction time, and complicated procedure. The base-catalyzed versions of these
4
4-47
reactions were reported recently
.
5
,6,48,49
To date, there are significant numbers of catalysts based on MOFs with mono active sites
.
There are only a few reported examples respecting the catalytic study of multifunctionalized
5
0-55
MOFs
.
In this study, the imine functionalized V-shaped ligand N,N'-(oxybis(4,1-phenylene))bis(1-
pyridin-4-yl)methanimine) (OPP) (Scheme S.1) and a new mixed ligand MOF,
[Cd (BDC) (OPP)(DMF) ].2DMA} (TMU-33) with acceptable thermal stability, was
(
{
3
3
2
n
synthesized. Since Hantzsch reaction occurs with both acidic and basic catalysts, we wish to use
TMU-33 as a heterogeneous cooperative catalyst that could have open metal site as Lewis acid
and functionalized basic ligand for selective synthesis of Hantzsch 1, 4-DHPs (Scheme 1). In
order to investigate the effect of size reduction, TMU-33 have been readily and quickly
synthesized by sonochemical process. In addition, the modulation synthesis to achieve specific
5
6
morphology as well as to limit crystal growth in certain dimensions were used . Relative
frequency of each catalytic site in different morphologies and comparing of their catalytic
performance in this reaction and also, the reusing feasibility of this cooperative catalyst were
4

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investigated. High and fast catalytic activity were observed in ambient temperature and the
catalyst could be reused without significant loss of activity.
Scheme 1. Synthesis of Hantzsch 1, 4-dihydropyridines.
2. Experimental
2.1. Materials and measurements
The used materials as reagents were purchased from Sigma-Aldrich and Merck companies and
used as received without further purification. Melting points of the products were measured on
an Electrothermal 9100 apparatus. A Thermo Scientific Nicolet IR100 (Madison, WI) Fourier-
transform infrared (FT-IR) spectrometer was used to record the IR spectra. A computer-
controlled PL-STA 1500 apparatus was employed to analysis the thermogravimetric behavior of
the structures (TGA). For this purpose, Single-phased powder samples of TMU-33 were loaded
into alumina pans and heated with a ramp rate of 10 °C/min from ambient temperature to 800 °C
in a static atmosphere of nitrogen. X-ray powder diffraction (XRD) measurements were done
5

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with a Philips X’pert diffractometer with monochromated Cu-kα radiation (λ=1.54056A). Based
on single crystal data, the simulated XRD powder pattern was performed using Mercury
software. An Echrom GC A90 gas chromatograph was used to monitoring the progress of the
catalytic reactions. The morphology of samples was investigated with scanning electron
microscope (SEM) (Philips XL 30) with a gold coating.
2.2. Preparation of N,N'-(oxybis(4,1-phenylene))bis(1-(pyridin-4-yl)methanimine) (OPP)
1.201 g (6 mmol) of 4, 4′-Oxydianiline dissolved in (5 ml) DMF added dropwise to a solution of
4-Pyridinecarboxaldehyde (1.2 mL, 12 mmol) in ethanol (15 mL). Two drops of formic acid
were added and the mixture was stirred at ambient temperature for 4 h. The yellow residue was
filtered and washed three times with 15 ml of cold ethanol and air-dried. Yield, 83% based on 4,
-
1
4
-oxydianiline. FT-IR (cm ): 1625.80 (w), 1580.95(s), 1494.54 (vs), 1406.73(m), 1255.74(vs),
1102.49(w), 978.07(m), 345.48(vs), 637.02(w), 345.39(s).
2
.3. Synthesizes of {[Cd (BDC) (OPP)(DMF) ].2DMA} (TMU-33)
3
3
2
n
A mixture containing terephthalic acid (H BDC) (0.0188 g, 1 mmol), Cd(NO ) ·4H O (0.3048 g,
2
3 2
2
1
mmol), OPP (0.378 g, 1 mmol) in DMF (15 mL) was sealed in a Teflon-lined autoclave and
heated at 100 °C under autogenous pressure for three days and then allowed to cool to room
temperature gradually during 24 h. The yellow crystals were washed with DMF and air-dried.
2
Yield: 52% (based on Cd ). FT-IR (cm ): 3288(m), 2926 (w), 2857(w), 1663.36 (s),
+
-1
1569.04(vs), 1494.02(m), 1392.07(s), 1248.50(s), 1097.31(w), 1009.16(w), 825.04(m),
743.06(m), 651.16(w), 533.47(m), 507.57(m). Elemental analysis (%) calculated: C 48.24, H
4.01, N 7.76. Found: C 48.27, H 4.11, N 7.8. Before catalysis process, the crystals were placed at
200 °C under vacuum for 2 h. Then, for removing coordinated solvent, aforementioned sample
6

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were immersed in 5 mL of CH CN for 3 days and fresh CH CN added every 12 h. After 3 days
3
3
the CH CN solution was decanted and dried at 80 °C at least 12 h.
3
2.4. Synthesis of TMU-33 Nanostructures
The same process was applied to synthesize TMU-33 via sonochemical reaction in an ultrasonic
bath at ambient temperature (RT) and atmospheric pressure. For the study of the concentration
effect of the initial reagents on size and morphology of nano-structured TMU-33, the above
processes were performed with concentrations of [H BDC] = [Cd(OAc) .4H O] = [OPP ligand]
2
2
2
of [0.05], [0.01] and [0.005] M. For nanorods and nanoplates TMU-33, the above processes were
performed with concentrations of [H BDC] = [Cd(OAc) .4H O] = [OPP ligand] of [0.05] by
2
2
2
adding different concentrations of benzoic acid and pyridine as capping reagents (modulator) at
ambient temperature for 20 min, respectively. For nanorod TMU-33, r factors, where r is defined
as the ratio of concentration of modulator to H BDC were 5 and 2, and r factors for
2
[
pyridine]/[OPP ligand] about nanoplates also were 5, and 2. The resulting powder was isolated
by centrifugation, washed with DMF three times and dried in air before characterization.
2.5. General procedure for the synthesis of Hantzsch 1,4-Dihydropyridine (1,4-DHPs)
Aldehyde (1 mmol), ethyl acetoacetate (2 mmol) and ammonium acetate (1 mmol) were stirred
together followed by the addition of a catalytic amount of TMU-33 (4 mol %) in different
solvents (1.5 mL) such as ethanol, methanol, distilled water, acetonitrile, dichloromethane and
chloroform for the appropriate time. The progress of the reaction was followed by GC analysis.
On completion of the reaction time, the MOF was recovered by centrifugation at 10000 rpm for
4
minutes and 0.5 µl of the supernatant liquid was collected and injected to GC. The compounds
7

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1
were fully characterized by mp, IR and H NMR spectroscopy, which are provided in SI section.
The catalyst was washed repeatedly with EtOH, dried at room temperature and reused.
2.6. Crystallographic data collection and refinement
Crystallographic characterizations of TMU-33 were done with a X-Area area-detector
diffractometer. The intensity data of TMU-33 were collected using graphite monochromated
Mo–Kα radiation (λ=0.71073 Å) at 298 K. Data reduction was carried out using the X-Area
5
software. . The direct methods by SHELXL-2017 was used to solve the structure . Also, the
7
58
5
refinement and all further calculations were done by SHELXL-2017 . H-atoms were included
8
in calculated positions and regarded as riding atoms. The refinement of the non-H atoms was
2
done anisotropically by weighted full-matrix least-squares on F . Crystallographic data and
structure refinements of compound TMU-33 are reported in Table S1.
3. Result and discussion
The V-shaped imine functionalized ligand, (OPP), designed and synthesized for the first time.
The angled conformation around etheric O atom creates the appropriate flexibility for acceptance
5
of coordination geometries of metal and make the fine structure . Using flexible OPP ligand,
9
linear 1,4-benzenedicarboxylic acid (H BDC) and Cd(NO ) .4(H O), porous three-dimensional
3 2
2
2
framework {[Cd (BDC) (OPP)(DMF) ].2DMA} with 1D channels along the b axis was
3
3
2
n
synthesized. The imine based spacer can act as a pillar to link the metal-carboxylate layer to
6
produce higher dimensional frameworks containing the channels or cavities .
0
8

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Fig. 1. (A) 2-Fold interpenetration of TMU-33, (B) and (C) The pore of the framework (D) 1D
channels along the b axis.
Double interpenetration of this crystalline framework tune pore size of 6.6 × 6.4 Å (Fig. 1). As
shown in Fig. S.1, thermogravimetric analysis of the compound shows the loss of two free
dimethylamine (DMA) molecules and two coordinated DMF molecules in the temperature range
of 25-260 °C (calc.: 16.3%, found: 15%). Then the loss of coordinated OPP ligand causes the
chemistry decomposition of the framework at about 300 °C. XRD pattern and TG analysis of
TMU-33 step by step after remove DMA and DMF molecules are shown in Fig. 2.
9

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Fig. 2. (A) XRD pattern and (B) Thermogravimetric analysis (TGA) of TMU-33 step by step
after remove DMA and DMF molecules related to TMU-33, TMU-33 (A) and TMU-33(B).
TMU-33 crystallizes in the monoclinic space group C /c. Analysis of the single crystal X-ray
2
diffraction data indicates that the asymmetric unit of this MOF contains two crystallographically
2
-
distinct cadmium cations (Cd and Cd ), which Cd (x,y,z) coordinated to three bidentate BDC
1
2
1
anions, one OPP ligand and one DMF molecule. As shown in Scheme S.2, carboxylate groups of
2
Cd choose two different coordination modes: Two BDC adopt the chelating-bridging tridentate
-
1
6
mode, whereas another carboxylate group is in two coordination modes . Cd (x+1/2, y+1/2, z)
1
2
is localized on a special position and coordinated to 6 carboxylate anion in two different modes
2
in which 4 BDC anion are in the chelating-bridging tridentate mode and two others adopt to
-
two coordination mode.
The Cd atom is bridged by carboxylate ligands to form a trinuclear cluster unit Cd …Cd …Cd
1
2
1
2
with the Cd …Cd distance of 3.610(1) Å (Fig. 3). The Cd center is seven coordinated by 5O
1
2
1
1
0

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atoms of carboxylate anions (O , O , O , O , O ), O from DMF molecule and N from
2
2
3
4
6
7
8
2
monodentate OPP ligand in equatorial position. Six O atoms from six carboxylate BDC anions
-
form a six-coordinate octahedral geometry around Cd . About Cd , the four O atoms are
2
1
approximately in a plane, the Cd-O lengths are in the range 2.29(1)-2.48(1)Å , Cd -O (from DMF
1
molecule) is 2.33(1) Å and Cd -N length is 2.32(1) Å. Cd-O distances in Cd are in the range of
1
2
2
.209(8)-2.41(1) Å. Each trinuclear metal cluster coordinates to six carboxylate anions to form a
D framework containing rectangle channels (6.6 × 6.4 Å) along b axis that filled by two non-
3
coordinated DMA molecules that form from partial hydrolysis of DMF solvent during synthesis
6
2,63
.
2
Fig. 3. Asymmetric unit of TMU-33 (The green nodes for Cd cations, the blue nodes for O
+
atoms and the pink nodes for N atoms and all hydrogens have been omitted for clarity).
TMU-33 has been readily synthesized by sonochemical process. Comparison between the
simulated (derived from the single crystal structures of TMU-33) and experimental sonochemical
1
1

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synthesized powder X-ray diffraction (PXRD) patterns confirm that nanosized of TMU-33 were
structurally identical to TMU-33 prepared via conventional heating (Fig. 4A).
Fig. 4. (A) XRD pattern and (B) SEM images of TMU-33 (i) and (ii) sonochemical synthesized
sample.
The morphology and size of TMU-33 were studied with scanning electron microscopy (SEM) by
changing three parameters; concentration of starting reagents (Cd(OAc) ·4H O, H BDC, and
2
2
2
OPP), sonication time and sonication power in order to control of nucleation. Sonication time
and power as parameters were changed at a constant concentration of [0.001] M of starting
materials that among all concentrations had the best morphology. Concentration ([0.001] M) of
1
2

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starting materials, 20 minutes for sonication time and 24W as sonication power were selected as
optimum conditions (Fig.4B and Fig. S.2).
As mentioned above, about TMU-33 the H BDC ligands bind to Cd units and form 2D sheets
2
3
that are connected through the V-shaped OPP ligand, to form a three-dimensional framework.
Nanorod and nanoplate TMU-33 were synthesized by mixing a constant concentration of initial
reagents in optimal conditions by using different concentrations of benzoic acid and pyridine as
capping reagents, respectively. Since monocarboxylic acid (benzoic acid) has the same
carboxylate functionality as the H BDC ligand and is expected to efficiently inhibit the
2
coordination interactions between cadmium and BDC ligand, was chosen as capping agent. In
addition, benzoic acid can be influenced on the nucleation rate via controlling of deprotonation
process of H BDC during the compound formation and therefore moderate size and aspect ratio
2
of MOFs. On the other side, pyridine having a nitrogen atom with a lone pair was chosen to
compete with the N-donor pillar ligands for coordinating to metal centers. Furthermore, unlike
Cd(II) nitrate, cadmium(II) acetate produces a precipitate of MOF upon mixing with other
reagents, and for this reason is selected as an alternative reagent which is more suitable for
5
control through the coordination modulation . Various “r” ratios (where r= [modulator]/
6
[
ligand]) have been used to produce rod- and plate like morphologies. It has been found that
when the ratio between modulator and ligand was reduced from r = 5 to r = 2 in constant
concentration of BDC and OPP ligand (c = 0.001 M), nano rods and nano plates with reduced
size have been obtained (Fig. 5(A,B) and Fig. S.3). This is ascribed to this fact that increasing
the concentration of modulator results in the decrease of the nucleation rate and increase of the
64,65
particle sizes
. Samples with desire morphologies were activated by soaking in CH CN and
3
1
3

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heating in an oven at 200 °C for 2 h under vacuum. The morphologies of the structures remain
intact upon removal of guest DMA and coordinated DMF molecules (Fig. 5 (C, D)).
Fig. 5. SEM images of (A) nanoplate with r=2 of capping agent (pyridin), (B) nanorod with r=2
of capping agent (benzoic acid), (C) sample A after activation by heating, TMU-33(D) and (D)
sample B after activation by heating, TMU-33(E).
The X-ray diffraction (XRD) patterns of nanorod and nanoplate are similar to the simulated
pattern of TMU-33 indicating the unchanged structures (Fig. 6). It is also noted that for the
nanoplates, the relative intensities of (20-2) and (200) reflections in comparison with (11-1) are,
respectively, larger and smaller than that in the simulated pattern. This is ascribed to crystal
growth along the [10-1] direction and inhibition of crystal growth along the [100] direction in the
1
4

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presence of pyridine. On the contrary, for nanorods the reflection intensity becomes reversed
because benzoic acid as modulator is utilized.
Fig. 6. (A) XRD patterns of nanoplate (TMU-33(D) and nanorod TMU-33(E) and (B)
Representation of the (200) and (20-2) planes in TMU-33.
1
5

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To evaluate the effectiveness of TMU-33 as a cooperative catalyst, and compare the ability of
each of the catalytic sites in these reactions and also in order to study the effect of size, catalytic
studies were divided into five categories. About catalyst (A), the DMA molecules that occupied
pores removed by heating and only OPP ligand as base was the catalyst in the reaction. The
DMA molecules and coordinated DMFs removed by heating and solvent exchange, respectively,
for catalyst (B), which have both catalytic zone. Catalyst (C) was the optimized nano synthesized
sample. Catalyst (D) has nanoplate morphology and the relative accessibility of Lewis acid are
more than Brønsted base in this nanostructures. Catalyst (E) has nanorod morphology and the
relative accessibility of catalytic site in this framework is inverse of nanoplates. At first three
component reaction of benzaldehyde, 2 equivalent ethyl acetoacetate, ammonium acetate and
TMU-33(A) in different solvents at ambient temperature was performed and the results are listed
in Table 1. It should be noted that the stability of framework in solvents was studied by XRD
and IR spectroscopy after immersing MOF in different solvents for 24 h and proves acceptable
durability of framework in this solvents (Fig. 7).
Fig. 7. (A) XRD pattern and (B) IR spectrum of TMU-33 after 24h soaking in different solvents.
1
6

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Table 1. The one-pot three component reaction of benzaldehyde, ethyl acetoacetate, ammonium
acetate and TMU-33(A) in different solvents.
a
b
Entry
Cat.
Mol% cat.
Solvent
EtOH
Time (h) Temp (°C) % Yield
1
2
3
4
5
6
7
8
9
--
4
4
4
4
4
4
4
4
6
4
4
4
4
4
4
4
4
4
2
2
2
2
2
2
2
2
2
1
4
24
2
2
2
2
2
2
25
25
25
25
25
25
25
25
25
25
25
25
45
65
25
25
25
25
12.5
62
TMU-33(A)
TMU-33(A)
TMU-33(A)
TMU-33(A)
TMU-33(A)
TMU-33(A)
TMU-33(A)
TMU-33(A)
TMU-33(A)
TMU-33(A)
TMU-33(A)
TMU-33(A)
TMU-33(A)
TMU-33(B)
TMU-33(C)
TMU-33(D)
EtOH
H O
2
48.5
40.1
31.2
16.5
13.4
22.8
68
MeOH
CH CN
3
CHCl3
CH Cl
2
2
c
----
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
1
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
8
49.3
78.4
91.2
79.3
80.8
84.1
96.8
75
TMU-33(E)
65.3
a
b
Solvents (1.5 mL). Isolated yield. Solvent-free conditions.
c
1
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The results demonstrated that higher yields were acquired in polar protic solvents compared with
solvents with lower polarity. It is necessary to mentioned that in the absence of catalyst, the
reaction rate was slow and even after extended reaction time, the reaction yields were still low.
In order to optimize the condition involving time, temperature and the amount of catalyst, some
further reactions in the present of TMU-33(A) were carried out. Catalytic activity of TMU-33(A)
(62% yield after 2 h) is the result of imine groups of OPP ligands in the structure. In the second
stage, optimized condition was applied at present of TMU-33(B), the results show that the
presence of open Cd site serve as catalyst and improve the catalytic behavior of the framework
(84% yield after 2 h), as expected. Based on the observed results, when the framework is fully
activated, both catalytic sites are available for reaction and its efficiency increases. Thus the
following mechanism (Scheme 2) for this catalytic reaction is suggested. So the Lewis acid
involved in activation of ethyl acetoacetate and aldehyde as well as base is responsible for the
absorption of hydrogen from ethyl acetoacetate. TMU-33(C), TMU-33(D) and TMU-33(E) were
also used as catalyst in optimum condition. According to our results presented here, TMU-33(C)
with 96% yield after 2 h has much higher activity toward the condensation of benzaldehyde with
ethyl acetoacetate and ammonium acetate as compared to the others. Based on the results it can
be suggested that when the catalyst particles size decreased to nanoscale, more of both types of
catalytic site involved in the reaction and yields reaches to the maximum amount. Both of TMU-
33(D) and TMU-33(E) catalysts are at the nanoscale and easy access to the catalytic sites for the
starting materials is possible, and the only factor that affects the catalytic yields is the difference
between the effectiveness of catalytic sites. Catalytic activity recorded for nanoplate morphology
of TMU-33(D) (75% yield after 2 h) is to some extent higher than nanorod morphology (65%
yield after 2 h) and it can be concluded that the acidic sites in our catalyst are more effective than
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the existing base in the structure. However, the higher catalytic efficiency of the TMU-33(C)
than that of TMU-33(B) and the higher catalytic efficiency of the TMU-33(E) than that of TMU-
33(A) which have same catalytic sites, shows that reduction of catalyst size improves access of
raw materials to them.
Scheme 2. Plausible mechanism for the synthesis of 1, 4-DHPs using TMU-33 as a cooperative
catalyst.
To examine the general application of the catalyst (TMU-33), we extended the scope of the
reaction to the synthesis of various 1, 4-DHPs under the above-mentioned optimized conditions
(Table 2). These reactions proceeded smoothly and no undesirable side reactions were observed.
Based on the results, besides that nanoscale catalysts had better efficiency than similar bulk-sized
samples, the results show that the presence of the electron withdrawing groups on the aldehyde
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leads to greater desirability for the condensation reaction, so will be less need for acid catalysts
and have good performance. In such cases, presence of nanorod TMU-33(D) and TMU-33(A) by
more basic catalytic site, could be more effective.
a
Table 2. Synthesis of various 1, 4-DHPs in the present of TMU-33.
Yield
Yield
Yield
Yield
Yield
Mp (°C)
R
6
6
TMU-33(A) TMU-33(B) TMU-33(C) TMU-33(D) TMU-33(E)
found (reported)
C H
6
62.3
69
84
89.7
85
96.8
97
75
70.2
72
65.3
76
200–203 (200–202)
210–212 (209–211)
200–202 (199–201)
208–211 (207–210)
200–202 (199–201)
200–202 (199–201)
220–223 (225–226)
5
4
-Cl–C H
6 4
4
-Br–C H4
6
68.9
75
95
73.7
80.1
65
4
-NO –C H
4
83.2
80.7
82
96
77.5
73.2
79
2
6
4
-Me–C H4
6
60.8
70
93.6
95.1
92
4
-MeO–C H4
6
72
4
-OH-C H
6
58
73.8
77.9
70.5
4
a
Solvent: EtOH, Temperature: R.T, Amount of cat: 4 mol%, Time: 2h
Comparing the performance of TMU-33 (C) with some of similar works as catalyst for synthesis
of Hantzsch 1, 4-DHPs by condensation of benzaldehyde with ethyl acetoacetate and ammonium
are shown in Table 3. High efficiency, low response time and small amount of required catalyst
are the most striking feature of TMU-33 (C).
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a
Table 3. Comparing the performance of different catalysts in the reaction of Hantzsch 1, 4-DHP
Catalyst
TMU-33(cooperative)
Time(h) amount of cat T(°C) Yield (%)
2
4
4mol%
10mol%
10mol%
10mol%
10mol%
0.1g
R.T
reflux
reflux
reflux
reflux
60
96
49
54
57
60
80
76
96
95
77
90
48
72
61
6
7
FeCl .6H O (Lewis acid)
3
2
67
CuCl (Lewis acid)
4
67
ZnCl2 (Lewis acid)
4
67
InCl3 (Lewis acid)
4
6
8
Silica-sulphonic acid ( acidic)
0.8
5
6
Fe-TUD-1 ( acidic)
9
0.02 mmol Fe reflux
7
0
Alginic acid ( acidic)
0.83
0.33
3
10mol%
0.0g5
reflux
80
7
1
HClO –SiO
4
acidic)
(
2
7
Zr-SBA-16 ( acidic)
2
0.06 mmol Zr
4mol%
80
7
IR-MOF-3 ( basic)
3
5
reflux
60
7
T-BuOH ( basic)
4
5
10mol%
20mol%
0.05g
7
Triphenylphosphine ( basic)
5
5
reflux
R.T
4
Hydrotalcite ( basic)
4
6.5
a
One pot reaction of 1mmol benzaldehyde, 2mmol ethyl acetoacetate and NH OAc in the present of
4
catalyst.
Moreover, the feasibility of recycling and reusing the cooperative catalyst were then investigated
for model compound. TMU-33 (C) could be reused at least 4 runs without a significant reduction
of its activity (Fig. 8). In heterogeneous catalysis it is important to check for the possible
occurrence of any leaching. Chemical analysis of the reaction medium after filtration of the
7
6
catalyst can provide information on catalyst leaching during reaction. In these cases, where no
metal traces are detected in the reaction medium after filtration of the catalysts. Also it is shown
in Fig. S.4, no significant differences are observed between the diffractograms, which indicates
that the crystalline structure of the material is preserved.
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Fig. 8. (A) FT-IR spectra and (B) XRD pattern of recovered TMU-33 (C) after five runs (red)
and as-synthesized TMU-33 (C) (black).
4. Conclusions
In this study, a 3D MOF, {[Cd (BDC) (OPP)(DMF) ].2DMA} by use of a new V-shaped imine
3
3
2
n
functionalized ligand (OPP) was synthesized and its performance as a solid cooperative catalyst
for Hantzsch 1, 4-dihydropyridines was investigated. TMU-33 has both acidic and basic catalytic
activity cause of the Lewis acidity of open Cd and Brønsted basicity of imine group of OPA
pillar, respectively. The nanosized, nanorod and nanoplate morphologies of TMU-33 by
sonochemical reaction and by adding capping agent were prepared and examined as catalyst for
the reaction. Relative accessibility of each catalytic site in different morphologies and comparing
of their catalytic performance in this reaction was investigated. High and fast catalytic activity
was obtained in nanoscale catalysts at ambient temperature and the acidic sites in this
cooperative catalyst were more effective than the existing base in the TMU-33.
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Acknowledgements
Support of this investigation by Tarbiat Modares University is gratefully acknowledged.
5. References
1
.
.
Hoskins, B.; Robson, R. Journal of the American Chemical Society 1990, 112, 1546-1554.
Fujita, M.; Kwon, Y. J.; Washizu, S.; Ogura, K. Journal of the American Chemical Society 1994,
2
1
16, 1151-1152.
3.
Kuppler, R. J.; Timmons, D. J.; Fang, Q.-R.; Li, J.-R.; Makal, T. A.; Young, M. D.; Yuan, D.;
Zhao, D.; Zhuang, W.; Zhou, H.-C. Coordination Chemistry Reviews 2009, 253, 3042-3066.
4
.
.
Farha, O. K.; Hupp, J. T. Accounts of chemical research 2010, 43, 1166-1175.
5
Evans, O. R.; Ngo, H. L.; Lin, W. Journal of the American Chemical Society 2001, 123, 10395-
1
0396.
6.
Horike, S.; Dinca, M.; Tamaki, K.; Long, J. R. Journal of the American Chemical Society 2008,
30, 5854-5855.
1
7.
8.
9.
Tanabe, K. K.; Cohen, S. M. Angewandte Chemie 2009, 121, 7560-7563.
Cohen, S. M. Chemical reviews 2011, 112, 970-1000.
Suslick, K. S.; Bhyrappa, P.; Chou, J.-H.; Kosal, M. E.; Nakagaki, S.; Smithenry, D. W.; Wilson,
S. R. Accounts of chemical research 2005, 38, 283-291.
10.
11.
12.
Wu, C.-D.; Hu, A.; Zhang, L.; Lin, W. Journal of the American Chemical Society 2005, 127,
8
940-8941.
Alaerts, L.; Séguin, E.; Poelman, H.; Thibault‐Starzyk, F.; Jacobs, P. A.; De Vos, D. E.
Chemistry–A European Journal 2006, 12, 7353-7363.
i Xamena, F. X. L.; Abad, A.; Corma, A.; Garcia, H. Journal of Catalysis 2007, 250, 294-298.
2
3

New Journal of Chemistry
Page 24 of 29
View Article Online
DOI: 10.1039/C7NJ01509G
13.
Llabrés i Xamena, F. X.; Corma, A.; Garcia, H. The Journal of Physical Chemistry C 2007, 111,
0-85.
8
14.
15.
16.
Hantzsch, A. Justus Liebigs Annalen der Chemie 1882, 215, 1-82.
Biginelli, P. Gazz. chim. ital 1893, 23, 360-413.
Bossert, F.; Meyer, H.; Wehinger, E. Angewandte Chemie International Edition in English 1981,
2
0, 762-769.
17.
18.
19.
Nakayama, H.; Kanaoka, Y. Heterocycles 1996, 42, 901–909.
Shaabani, A.; Bazgir, A.; Teimouri, F. Tetrahedron letters 2003, 44, 857-859.
Li, J.-J., Corey, E. J. In Name Reactions in Heterocyclic Chemistry; John Wiley & Sons, Inc.,
2
005; p. 301.
20.
21.
22.
23.
24.
Suzuki, I.; Suzumura, Y.; Takeda, K. Tetrahedron letters 2006, 47, 7861-7864.
Sve, J.; Veizerová, L.; Kettmann, V. Tetrahedron Letters 2008, 49, 3520-3523.
Karimi, B.; Zamani, A.; Abedi, S.; Clark, J. H. Green Chemistry 2009, 11, 109-119.
Kormos, C. M.; Hull, R. M.; Leadbeater, N. E. Australian journal of chemistry 2009, 62, 51-57.
Kumar, B.; Masih, P.; Lukose, C. R.; Abraham, N.; Priya, D.; Xavier, R. M.; Saji, K.; Adhikary,
L. Journal of Heterocyclic Chemistry 2009, 46, 336-339.
25.
26.
27.
Hu, E. H.; Sidler, D. R.; Dolling, U.-H. The Journal of Organic Chemistry 1998, 63, 3454-3457.
Rodríguez-Domínguez, J. C.; Bernardi, D.; Kirsch, G. Tetrahedron Letters 2007, 48, 5777-5780.
Reddy, C. V.; Mahesh, M.; Raju, P.; Babu, T. R.; Reddy, V. N. Tetrahedron Letters 2002, 43,
2
657-2659.
2
8.
9.
Zhang, Z.-H.; Yin, L.; Wang, Y.-M. Catalysis Communications 2007, 8, 1126-1131.
Ramalinga, K.; Vijayalakshmi, P.; Kaimal, T. Synlett 2001, 2001, 0863-0865.
2
2
4

Page 25 of 29
New Journal of Chemistry
View Article Online
DOI: 10.1039/C7NJ01509G
30.
Fu, N.-Y.; Yuan, Y.-F.; Cao, Z.; Wang, S.-W.; Wang, J.-T.; Peppe, C. Tetrahedron 2002, 58,
801-4807.
4
31.
32.
33.
34.
35.
36.
37.
Ranu, B. C.; Hajra, A.; Jana, U. The Journal of organic chemistry 2000, 65, 6270-6272.
Babu, G.; Perumal, P. ChemInform 2000, 31.
Ko, S.; Sastry, M.; Lin, C.; Yao, C.-F. Tetrahedron letters 2005, 46, 5771-5774.
Gogoi, P.; Konwar, D. Tetrahedron Letters 2006, 47, 79-82.
Cepanec, I.; Litvić, M.; Bartolinčić, A.; Lovrić, M. Tetrahedron 2005, 61, 4275-4280.
Wan, J.-P.; Gan, S.-F.; Wu, J.-M.; Pan, Y. Green Chemistry 2009, 11, 1633-1637.
Yadav, J. S.; Reddy, B. V. S.; Srinivas, R.; Venugopal, C.; Ramalingam, T. Synthesis 2001, 2001,
1
341-1345.
3
8.
9.
Varala, R.; Alam, M. M.; Adapa, S. R. Synlett 2003, 2003, 0067-0070.
3
Yadav, J.; Reddy, B. S.; Premalatha, K.; Shankar, K. S. Canadian Journal of Chemistry 2008, 86,
1
24-128.
4
0.
1.
Paraskar, A.; Dewkar, G.; Sudalai, A. Tetrahedron Letters 2003, 44, 3305-3308.
4
Wang, P.; Wang, J.; Au, C. T.; Qiu, R.; Xu, X.; Yin, S. F. Advanced Synthesis & Catalysis 2016,
3
58, 1302-1308.
42.
Wang, J.; Li, N.; Qiu, R.; Zhang, X.; Xu, X.; Yin, S.-F. Journal of Organometallic Chemistry
015, 785, 61-67.
2
43.
44.
45.
Sabitha, G.; Reddy, G. K. K.; Reddy, C. S.; Yadav, J. Tetrahedron Letters 2003, 44, 4129-4131.
Antonyraj, C. A.; Kannan, S. Applied Catalysis A: General 2008, 338, 121-129.
Debache, A.; Amimour, M.; Belfaitah, A.; Rhouati, S.; Carboni, B. Tetrahedron Letters 2008, 49,
6
119-6121.
2
5

New Journal of Chemistry
Page 26 of 29
View Article Online
DOI: 10.1039/C7NJ01509G
46.
47.
48.
49.
50.
51.
Chitra, S.; Pandiarajan, K. Tetrahedron Letters 2009, 50, 2222-2224.
Hida, T.; Nogusa, H. Tetrahedron 2009, 65, 270-274.
Bhattacharjee, S.; Yang, D.-A.; Ahn, W.-S. Chemical Communications 2011, 47, 3637-3639.
Wu, X.; Tamm, M. Coordination Chemistry Reviews 2014, 260, 116-138.
Pan, Y.; Yuan, B.; Li, Y.; He, D. Chemical Communications 2010, 46, 2280-2282.
Vermoortele, F.; Ameloot, R.; Vimont, A.; Serre, C.; De Vos, D. Chemical Communications
2
011, 47, 1521-1523.
52.
Wu, P.; Wang, J.; Li, Y.; He, C.; Xie, Z.; Duan, C. Advanced Functional Materials 2011, 21,
788-2794.
2
5
3.
4.
Cirujano, F.; i Xamena, F. L.; Corma, A. Dalton Transactions 2012, 41, 4249-4254.
5
Li, B.; Zhang, Y.; Ma, D.; Li, L.; Li, G.; Li, G.; Shi, Z.; Feng, S. Chemical Communications
2
012, 48, 6151-6153.
55.
Wu, P.; He, C.; Wang, J.; Peng, X.; Li, X.; An, Y.; Duan, C. Journal of the American Chemical
Society 2012, 134, 14991-14999.
56.
57.
58.
Masoomi, M. Y.; Beheshti, S.; Morsali, A. Crystal Growth & Design 2015, 15, 2533-2538.
Bruker, S.; SAINT, S. Madison, Wisconsin, USA 2002.
Sheldrick, G. M. Acta Crystallographica Section A: Foundations of Crystallography 2008, 64,
1
12-122.
5
9.
0.
Guo, H.; Yan, Y.; Guo, X.; Wang, N.; Qi, Y. Journal of Molecular Structure 2016, 1108, 134-
43.
1
6
Bhattacharya, B.; Maity, D. K.; Pachfule, P.; Colacio, E.; Ghoshal, D. Inorganic Chemistry
Frontiers 2014, 1, 414-425.
2
6

Page 27 of 29
New Journal of Chemistry
View Article Online
DOI: 10.1039/C7NJ01509G
61.
Hu, J.-S.; Shang, Y.-J.; Yao, X.-Q.; Qin, L.; Li, Y.-Z.; Guo, Z.-J.; Zheng, H.-G.; Xue, Z.-L.
Crystal Growth & Design 2010, 10, 4135-4142.
62.
63.
64.
Biemmi, E.; Bein, T.; Stock, N. Solid state sciences 2006, 8, 363-370.
Chen, J.; Ohba, M.; Kitagawa, S. Chemistry Letters 2006, 35, 526-527.
Tanaka, D.; Henke, A.; Albrecht, K.; Moeller, M.; Nakagawa, K.; Kitagawa, S.; Groll, J. Nature
Chemistry 2010, 2, 410-416.
65.
66.
67.
68.
69.
Jiang, D.; Burrows, A. D.; Edler, K. J. CrystEngComm 2011, 13, 6916-6919.
Kumar, P.; Hussain, K.; Kumar, A. Current Chemistry Letters 2014, 3, 75-84.
Debache, A.; Boulcina, R.; Belfaitah, A.; Rhouati, S.; Carboni, B. Synlett 2008, 2008, 509-512.
Sharma, P.; Gupta, M. Green Chemistry 2015, 17, 1100-1106.
Srinivasan, V. V.; Pachamuthu, M. P.; Maheswari, R. Journal of Porous Materials 2015, 22,
1
187-1194.
70.
71.
72.
Dekamin, M. G.; Ilkhanizadeh, S.; Latifidoost, Z.; Daemi, H.; Karimi, Z.; Barikani, M. RSC
Advances 2014, 4, 56658-56664.
Maheswara, M.; Siddaiah, V.; Rao, Y. K.; Tzeng, Y.-M.; Sridhar, C. Journal of Molecular
Catalysis A: Chemical 2006, 260, 179-180.
Maheswari, R.; Srinivasan, V. V.; Ramanathan, A.; Pachamuthu, M. P.; Rajalakshmi, R.; Imran,
G. Journal of Porous Materials 2015, 22, 705-711.
73.
74.
75.
Rostamnia, S.; Morsali, A. RSC Advances 2014, 4, 10514-10518.
Debache, A.; Chouguiat, L.; Boulcina, R.; Carbonib, B. Open Org. Chem. J 2012, 6, 12-20.
Debache, A.; Ghalem, W.; Boulcina, R.; Belfaitah, A.; Rhouati, S.; Carboni, B. Tetrahedron
Letters 2009, 50, 5248-5250.
2
7

New Journal of Chemistry
Page 28 of 29
View Article Online
DOI: 10.1039/C7NJ01509G
76.
i Xamena, F. L.; Casanova, O.; Tailleur, R. G.; Garcia, H.; Corma, A. Journal of Catalysis 2008,
55, 220-227.
2
2
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Graphical Abstract