Three-Dimensional Heterometallic Coordination Networks: Syntheses, Crystal Structures, Topologies, and Heterogeneous Catalysis

Article abstract of DOI:10.1021/acs.cgd.5b00697

This work presents the synthesis of {Co³⁺-Zn²⁺} and {Co³⁺-Cd²⁺} heterometallic coordination networks. These networks are originated from two unique Co³⁺-based metalloligands containing appended arylcarboxylic acid groups at the strategically placed positions. Such appended arylcarboxylate groups coordinate the secondary metal ions, Zn²⁺ and Cd²⁺, to afford distinct three-dimensional networks. All four networks display orderly arrangement of secondary metal ions and unique network topologies including an unprecedented one. These networks have been shown to act as the heterogeneous and reusable catalysts for the Knoevenagel condensation reactions and cyanation reactions of assorted aldehydes. Cyanation reactions nicely demonstrate the substrate size-exclusion catalysis.

Full text of DOI:10.1021/acs.cgd.5b00697

Page 1 of 17
Crystal Growth & Design
1
2
3
4
5
6
7
8
9
Three-dimensional Heterometallic Coordination Networks: Synthe-
ses, Crystal Structures, Topologies and Heterogeneous Catalysis
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Sumit Srivastava, Himanshu Aggarwal,† and Rajeev Gupta*
Department of Chemistry, University of Delhi, Delhi 110 007, India
ABSTRACT. This work presents the synthesis of {Co3+-Zn2+} and {Co3+-Cd2+} heterometallic coordination networks. These
networks are originated from two unique Co3+-based metalloligands containing appended arylcarboxylic acid groups at
the strategically placed positions. Such appended arylcarboxylate groups coordinate the secondary metal ions, Zn2+ and
Cd2+, to afford distinct three-dimensional networks. All four networks display orderly arrangement of secondary metal
ions and unique network topologies including an unprecedented one. These networks have been shown to act as the het-
erogeneous and reusable catalysts for the Knoevenagel condensation reactions and cyanation reactions of assorted alde-
hydes. Cyanation reactions nicely demonstrate the substrate size-exclusion catalysis.
Introduction
tion between a ligand and a metal ion. In addition, judi-
cious selection of the Lewis acidic and/or redox-sensitive
secondary metals in such designed materials has been
utilized by displaying homogeneous as well as heteroge-
neous catalysis.43-54 Herein, we report the syntheses, crys-
tal structures, topological analyses, and catalytic proper-
ties of two {Co3+-Zn2+} and two {Co3+-Cd2+} HCNs using
two different Co3+-based metalloligands offering append-
ed aryl carboxylic acid groups. These HCNs display inter-
esting network topologies including one unprecedented
topology. We further illustrate the applications of such
HCNs in heterogeneous catalysis for the Knoevenagel
condensation and cyanation reactions.
Coordination networks are important due to their well-
defined architecture1-10 and applications in sorption,11,12
separation,13,14 sensing,15-17 ion-exchange and transport,18,19
proton conduction,20-22 optics,23-27 magnetism,28,29 devic-
es,30,31 and catalysis.32-36 Due to their ordered architecture,
porosity, and stability; such materials have shown signifi-
cant results as the heterogeneous catalysts for assorted
organic transformations.32-40 It is important to note that
such catalytic properties are largely feasible due to the
crystalline nature and subsequent orderly arrangement of
catalytic sites and materials’ ability to support facile diffu-
sion of substrate and/or reagent.32-40 A large number of
homometallic coordination networks have been synthe-
sized and used for various applications including hetero-
geneous catalysis. On the other hand, heterometallic co-
ordination networks (HCNs) have not been explored in
such great deal due to the synthetic challenge of placing
two different metals in close proximity. HCNs typically
display higher thermal stability while also offering the
possibility to explore the influence of primary metal on
the properties of the secondary metal ion. In this context,
a well-defined metalloligand,1 already containing a prima-
ry metal ion, is most suited to react with a suitable sec-
ondary metal ion to produce HCNs.
Experimental Section
Materials and Methods. Reagents of analytical grade
were procured from the Sigma-Aldrich, Alfa-Aesar, and
Spectrochem and were used without further purification.
The solvents were dried and/or purified using standard
literature methods.55 The metalloligands [Co(L3,5-COOH)3]
(1) (where HL3,5-COOH = 5-(picolinamido)isophthalic acid)
and [Co(L4-COOH)3] (2) (where HL4-COOH = 4-[(pyridine-2-
carbonyl)-amino]benzoic acid) were synthesized as per
our recent reports.42,56
Synthesis of HCNs
[{(1)Zn3(H2O)5}•9H2O•C3H8O]n (3).
Our research group has developed several metallolig-
ands appended with assorted functional groups that af-
ford systematically designed ordered architectures.41-54
Depending on the number, position, and orientation of
the appended functional groups being offered from a
metalloligand; we have been able to showcase the synthe-
sis of hydrogen bonded assemblies,41,42 trimetallic com-
plexes43-46 as well as ordered 2D and 3D architectures.47-54
These examples illustrate the importance metalloligands
for the construction of HCNs compared to homometallic
networks typically obtained from the conventional reac-
Compound 3 was synthesized by treating a solution of
Zn(OAC)2.2H2O (0.53 g, 0.24 mmol) in CH3OH (2 mL)
with a solution of metalloligand 1 (0.1 g, 0.11 mmol) in
CH3OH (5 mL). The reaction mixture was stirred at room
temperature for 2 h. Subsequently, a yellow colored pre-
cipitate was collected, washed several times with metha-
nol, and dried under vacuum at ambient temperature.
The crude product thus obtained was re-dissolved in wa-
ter and layered with isopropyl alcohol at room tempera-
ture. After a period of three to four days, red colored crys-
ACS Paragon Plus Environment

Crystal Growth & Design
Page 2 of 17
tals of network 3, suitable for diffraction studies, were
obtained. Yield: 0.13 (85%). Anal. Calcd. for
filtrate was concentrated to afford the crude organic
1
2
3
4
5
6
7
g
product. This product was purified by the column chro-
matography on 100–200 mesh silica using 1:1
EtOAc/hexanes as the eluent. The products were identi-
fied, quantified, and analysed by GC and GC–MS tech-
C42H31CoN6O20Zn3.10H2O.C3H8O: C, 40.19; H, 3.67; N, 6.25;
Co, 4.38; Zn, 14.58%; Found: C, 40.44%; H, 4.09%; N, 6.38;
Co, 4.44; Zn, 15.02%. FTIR spectrum (attenuated total
reflectance (ATR), selected peaks): 3423 (OH), 1605
(COO), 1585 (C=O) cm-1. Absorption spectrum (solid
state; λmax/nm): 520, 350.
1
13
niques as well as H NMR and C NMR spectra whenever
required.
General Procedure for the Cyanation Reaction. In a
typical cyanation reaction, 2 mol% catalyst (3, 4, 5 or 6)
was added to a mixture of aldehyde (1 mmol) and
(CH3)3SiCN (5 mmol). The resulting mixture was stirred at
room temperature and the progress of the reaction was
monitored by TLC. After completion of the reaction, 2 mL
EtOAc was added to the reaction mixture and the solid
catalyst was filtered off. The filtrate was concentrated
under the reduced pressure. The crude product was puri-
fied by flash column chromatography on silica gel using
10% ethyl acetate/hexanes mixture as the eluent. The
products were isolated, quantified, and analysed by the
8
9
[{(1)2Cd4(H2O)4}•18H2O]n (4).
Compound 4 was synthesized in a similar manner with
an identical scale as that of network 3; however, using
Cd(OAc)2.2H2O instead of Zn(OAC)2.2H2O. Red colored
crystals of network 4 were obtained after a period of 5 – 6
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
d.
Yield:
0.12
g
(86%).
Anal.
Calcd.
for
C84H54Co2N12O34Cd4.18H2O: C, 37.83; H, 3.40; N, 6.30; Co,
4.42; Cd, 16.86; Found: C, 37.45%; H, 3.42%; N, 6.04; Co,
4.66; Cd, 16.55%. FTIR spectrum (ATR, selected peaks):
3422 (OH), 1561 (COO, C=O) cm-1. Absorption spectrum
(solid state; λmax/nm): 522, 345.
1
GC and GC–MS techniques and H NMR and 13C NMR
[{(2)2Zn2}{Na2(H2O)13}•7H2O]n (5).
spectral techniques.
Compound 5 was synthesized by treating a solution of
Zn(OAC)2.2H2O (0.62 g, 0.28 mmol) dissolved in CH3OH
(2 mL) with a solution of metalloligand 2 (0.1 g, 0.13
mmol) in CH3OH (5 mL). The reaction mixture was
stirred at room temperature for 1 h. A yellow colored
product was collected, washed several times with metha-
nol, and dried under vacuum at ambient temperature.
The crude product thus obtained was re-dissolved in wa-
ter and layered with tert-butyl alcohol at room tempera-
ture. After a period of three to four days, red colored crys-
tals of network 5, suitable for diffraction studies, were
Physical Methods. The FTIR spectra were recorded
with the Perkin-Elmer Spectrum-Two spectrometer with
Zn-Se ATR. The NMR spectral measurements were car-
ried out with a Jeol 400 MHz spectrometer with TMS as
the internal standard. The absorption spectra were rec-
orded either with Perkin-Elmer Lambda 25 or Lambda 35
spectrophotometers. The elemental analysis data were
obtained with an Elementar Analysen Systeme GmbH
Vario EL-III instrument. The metal contents (Co, Zn,
and/or Cd) were measured with the help of GBC Avanta
atomic absorption spectrometer using standard calibra-
tion plots. Gas chromatographic analyses were done with
the Perkin Elmer Clarus-580 instrument having Elite-5
column. GC−MS studies were performed with a Shimadzu
instrument (QP 2010) with an RTX-5SIL-MS column.
Thermal gravimetric analysis (TGA) was carried out with
DTG 60 Shimadzu at 5 °C min−1 heating rate under the
nitrogen atmosphere. The X-ray powder diffraction
(XRPD) studies were performed either with an X’Pert Pro
from Panalytical or a Bruker AXS D8 Discover instrument
(Cu Kα radiation, λ = 1.54184 Å). The samples were
ground and subjected to the range of θ =5−30° with a scan
rate of 1−0.72°/min at room temperature.
obtained. Yield: 0.095
g (83%). Anal. Calcd. for
C78H74Co2N12O31Zn2Na2.7H2O: C, 44.69; H, 4.23; N, 8.02;
Co, 5.62; Zn, 6.24%; Found: C, 44.78%; H, 4.53%; N, 8.61;
Co, 5.87; Zn, 6.01%. FTIR spectrum (ATR, selected peaks):
3423 (OH), 1605 (COO), 1585 (C=O) cm-1. Absorption
spectrum (solid state; λmax/nm): 540, 410.
[{(2)Cd(H2O)}{Na(H2O)5}•11H2O]n (6).
Compound 6 was prepared in a similar fashion with an
identical scale as that of network 5; however,
Cd(OAc)2.2H2O was used in place of Zn(OAC)2.2H2O.
Reddish-brown colored crystals of network 6 were ob-
tained after a period of 4 – 5 d. Yield: 0.13 g (87%). Anal.
Calcd. for C39H36CoN6O15CdNa.11H2O: C, 38.36; H, 4.79; N,
6.88; Co, 4.83; Cd, 9.20; Found: C, 38.06%; H, 5.14%; N,
6.74; Co, 5.07; Cd, 9.46%. FTIR spectrum (ATR, selected
peaks): 3422 (OH), 1561 (COO, C=O) cm-1. Absorption
spectrum (solid state; λmax/nm): 520, 350.
Single Crystal Structure Determination. Single crys-
tals suitable for the X-ray diffraction studies were grown
by the layering of alcohol (isopropyl alcohol or tert-butyl
alcohol) into an aqueous solution of the respective net-
work. The intensity data were collected at 293 K with an
Oxford XCalibur CCD diffractometer equipped with
graphite monochromatic Mo-Kα radiation (λ = 0.71073
Å).57 An empirical absorption correction was applied us-
ing spherical harmonics implemented in the SCALE3
ABSPACK scaling algorithm.57 The structures were solved
by the direct methods using SIR-9258 and refined by the
full-matrix least-squares refinement techniques on F2 us-
ing SHELXL-9759 in the WinGX module.60 The hydrogen
atoms were fixed at the calculated positions with isotropic
thermal parameters whereas all non-hydrogen atoms
General Procedure for the Knoevenagel Condensa-
tion. The respective aldehyde and malononitrile were
taken in 5 mL ethanol and the solid catalyst (1 mol-%, 3, 4,
5 or 6; based on the repeating unit of the network) was
added and the reaction mixture was stirred at 60 °C for 30
min. The progress of the reaction was monitored by TLC
using 5% EtOAc/hexanes. After completion of the reac-
tion, solvent was removed under the reduced pressure
and the residue was triturated with ethyl acetate. The
catalyst thus separated was collected by filtration, and the
ACS Paragon Plus Environment

Page 3 of 17
Crystal Growth & Design
Scheme 1. Synthesis of heterometallic coordination networks 3–6
were refined anisotropically. In all cases; hydrogen atoms
1
2
3
4
5
6
7
8
using metalloligands 1 and 2.
of the coordinated and lattice water molecules could not
be located from the difference Fourier map; however,
their numbers have been included in the empirical formu-
lae. In case of HCN 5, data were corrected for the disor-
dered water molecules by using the SQUEEZE procedure
implemented in PLATON61 which considerably improved
the structure convergence. For HCN 6, oxygen atoms
O10w, O13w, O14w, and O16w of lattice water molecules
were refined isotropically. Details of the crystallographic
data collection and structural solution parameters are
provided in Table 1.
Crystal structures
All four HCNs were characterized by the single crystal
X-ray diffraction studies to understand the network gen-
eration via the mediation of arylcarboxylate-appended
metalloligands. For all four networks, Table 2; and Tables
S 1 and S2 (Supporting Information) respectively provide
the selected bond distances and detailed bonding param-
eters.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
In all four HCNs, the central Co3+ ion is coordinated by
three bidentate ligands. Importantly, bidentate ligands
are arranged meridionally around the Co3+ ion. Such a
meridional geometry around the Co3+ ion, less symmet-
rical than that of conventional facial, results in unique
orientation of the appended arylcarboxylate groups. Such
an orientation of arylcarboxylate groups generates inter-
esting networks after coordination with the secondary
metal ions. The bidentate ligands ligate the Co3+ ion via
five-membered chelate rings between Namide and Npyridyl
atoms. The Co−Namide bond distances (avg. 1.941 - 1.949 Å)
are comparable to that of Co−Npyridine ones (avg. 1.933 -
1.940 Å). All diagonal angles are close to linear; ranging
from 173.1° to 176.7°, again suggesting a symmetrical ar-
rangement of donors around the Co3+ ion. As a result of
symmetrical bonding, the geometry around the Co(III)
ion is nearly octahedral. Notably, in all four networks; the
role of Co3+–based metalloligand is limited to structural
anchoring and directing the appended arylcarboxylate
groups to limited orientations. While HCNs 3 and 4 are
originated from metalloligand 1 offering two carboxylate
groups at 3- and 5- positions of the arene ring; networks 5
and 6 are constituted of metalloligand 2 with only one
carboxylate group at the 4-position of the arene ring.
Results and Discussion.
Synthesis and Characterization. The metalloligands
[Co(L3,5-COOH)3] (1) and [Co(L4-COOH)3] (2) contain append-
ed but uncoordinated arylcarboxylic acid groups. The
metalloligands 1 and 2 respectively offer six and three
appended arylcarboxylic acid groups at the strategically
placed positions. Such metalloligands on reaction with
secondary Zn(II) and Cd(II) ions provide the desired
HCNs 3 − 6 (Scheme 1). In each case, reaction with sec-
ondary metal ion resulted in a distinct colour change fol-
lowed by the precipitation of the product. The crude
product was recrystallized from water assisted by layering
either with isopropyl alcohol or tert-butyl alcohol. All
four HCNs exhibit strong bands between 1605−1577 cm−1
for the νcarboxylate stretches and broad features between
3400−3430 cm−1 due to the presence of coordinated as well
as lattice water molecules (Figures S1 and S2, Supporting
Information, SI).
HCNs 3 − 6 were also characterized by their diffuse-
reflectance absorption spectra (Figures S3 and S4, SI).
HCNs 3 and 4 display nearly identical spectra with ab-
sorption bands at ca. 520 and ca. 350 nm. On the other
hand, HCNs 5 and 6 exhibit spectral features at 540 and
410 nm and 520 and 350 nm, respectively. The low-energy
bands are tentatively assigned to the d−d transition based
in Co(III) core of the metalloligand whereas the high-
energy features are most probably charge-transfer in na-
ture.
Both HCNs 3 and 4 crystallized in the monoclinic cell
with P21/c space group. The unit cell of 3 contains 1 metal-
loligand, 3 Zn2+ ions, 5 coordinated water molecules, 1
lattice isopropyl alcohol and 9 lattice water molecules.
The structure of network 3 displays that the Co3+-based
metalloligands are connected through the secondary Zn2+
ions (Figure 1). Every metalloligand offers three appended
aryldicarboxylate groups therefore a total of six carbox-
ylate groups. Such arylcarboxylate groups coordinate sep-
arate Zn(II) ions leading to a 3D architecture. The six-
coordinated Zn1 ion is ligated to three Ocarboxylate atoms
from three different metalloligands and three water mole-
cules. The five-coordinated Zn2 ion ligates three Ocarboxylate
atoms from three different metalloligands and two water
molecules. The five-coordinated Zn3 ion is connected to
five Ocarboxylate atoms in which four donors are from two
metalloligands while the fifth one is from a separate
metalloligand. Notably, guest isopropyl alcohol is trapped
within crystal lattice with the help of hydrogen bonds (H-
bonds) involving Zn-bound water molecules as well as
lattice water molecules. Consequently, isopropyl alcohol
occupies the channels created in the packing of HCN 3.
The XRPD patterns of the freshly prepared samples of
HCNs 3 − 6 are in good agreement to those simulated
from the single-crystal structural data. Such a fact indi-
cates phase purity of the bulk crystalline sample (Figures
S5−S8, SI).
All four HCNs display a very similar thermal decompo-
sition profile (Figures S9 and S10, SI). The first weight
change, observed between 25 – 150 C, corresponds to the
loss of lattice as well as coordinated water molecules. This
weight loss is followed by the decomposition of the net-
works that respectively starts at ca. 300 ˚C for HCNs 3 and
4 and at ca. 350 ˚C for HCNs 5 and 6.
o
ACS Paragon Plus Environment

Crystal Growth & Design
Page 4 of 17
The unit cell of network 4 contains 2 metalloligands, 4 Topological Analyses. The topology for all four HCNs
Cd2+ ions, 4 coordinated and 18 uncoordinated water mol-
ecules. The molecular structure of 4 exhibits a 3D net-
work where Co3+-based metalloligands are connected
through the secondary Cd2+ ions (Figure 2). As noted for
3, every metalloligand offers six carboxylate groups. Inter-
estingly, four appended groups out of six coordinate to
two Cd2+ ions in the carboxylate form whereas the remain-
ing two groups exists as carboxylic acid and take part in
inter-molecular hydrogen bonding (H-bonding) with the
lattice water molecules. The six-coordinated Cd1 ion is
ligated to four Ocarboxylate atoms, two each from one metal-
loligand, whereas rest of the axial sites are occupied by
the water molecules. The seven-coordinated Cd2 ion is
ligated to four Ocarboxylate atoms, two each from every
metalloligand, and three water molecules.
was studied with the help of TOPOS 4.0.63,64 Although all
four networks are similar in terms of involving Co3+ based
metalloligands and secondary metal ions; their topologies
are considerably distinct from each other. It is noteworthy
that each network offers secondary building units (SBUs),
constituted of Zn2+ or Cd2+ ions that are coordinated to a
certain number of arylcarboxylate moieties.54,65-67 These
SBUs result in a number of nodes leading to different
types of topologies for each coordination network.65-72 In
each case, such SBUs expand through Co3+ metalloligand
units which themselves act as the nodes.54
Both HCNs 5 and 6 contain similar 3-connected Co3+
metalloligand nodes with point symbols {42.6} and {4.82},
respectively.65-67 Further, the arylcarboxylate groups are
connected to the secondary Zn2+ or Cd2+ ions to generate
Zn2(COO)6 (in 5) or Cd(COO)3 (in 6) SBUs that serve as
the 6-connected and 3-connected cluster nodes, respec-
tively. The TOPOS analysis provides flu type topology
with point symbol {42.6}2{44.62.87.102} and fes type topolo-
gy with point symbol 4.82 for 5 and 6, respectively (Fig-
ures 3e and 4e).
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Both HCNs 5 and 6, originated from metalloligand 2
appended with para-arylcarboxylate groups, crystallize in
the monoclinic cell with C2/c space group. The higher
symmetry associated with networks 5 and 6, when com-
pared to 3 and 4, immediately suggest the difference of
placing fewer number of arylcarboxylate groups on a
metalloligand in the former. The unit cell of HCN 5 con-
tains 2 metalloligands, 2 Zn2+ ions, 2 Na+ ions and 13 coor-
dinated water molecules. Any metalloligand offers three
para-arylcarboxylate groups and two such groups out of
three coordinate one Zn2+ ion whereas the remaining one
bridges two Zn2+ ions. A repetition of such a bonding pat-
tern generates a 3D network (Figure 3). The geometry
around the five-coordinated Zn(II) ion is severely distort-
ed with τ5 parameter of ca. 0.6.62 It may be noted that τ5
has ideal values of 0 and 1 for perfect square-pyramidal
and trigonal bipyramidal geometries, respectively.62 The
structure displays the presence of a Na2(OH2)13 cluster in
which two sodium ions are bridged by one water mole-
cule while coordinated to the rest of terminal water mole-
cules. Such a cluster is held in place by an array of H-
bonds involving Oamide and lattice water molecules.
In HCNs 3 and 4, every HL3,5-COOH ligand offers two
carboxylate groups, resulting in a total of 6 arylcarbox-
ylate moieties that can coordinate to the secondary Zn2+
or Cd2+ metal ions to form different types of SBUs.65-67
Besides this, both HCNs offer Co3+ metalloligand based
nodes which are 3-connected both for HCN 3 and 4 with
point symbols {5.82} and {3.102}, respectively. Interesting-
ly, in case of HCN 3, a new type of topology has been ob-
served where aryldicarboxylate groups bind with Zn2+ ions
to give rise to Zn(COO)4 and Zn3(COO)3 SBUs with 4-
connected nodes. Such SBUs are connected through the
Co3+ based metalloligands nodes generating a network
with the point symbol {5.6.7.82.9}{5.6.7}{5.82}2{5.83.92}{83}
(Figure 1e). In case of 4, aryldicarboxlyate groups give rise
to Cd(COO)2 and Cd(COO)4 SBUs. In Cd(COO)2, Cd2 is
bonded to two arylcarboxylate groups in chelating mode
resulting in a rod like connection. Since this Cd atom
(Cd2) does not act as a distinct node, it will not contrib-
ute towards the overall topology of the network. Hence,
there are only 3- and 4-connected nodes as a result of Co3+
based metalloligands and Cd1 centers, respectively. The
TOPOS analysis for HCN 4 generates the point symbol
{3.102}4{32.102.112} (Figure 2e).
The unit cell of network 6 contains 1 metalloligand, 1
Cd2+ ions, 1 Na+ ion, 6 coordinated and 11 lattice water
molecules. The molecular structure of 6 shows that the
metalloligands are connected through the secondary Cd2+
ions resulting in a 3D network (Figure 4). Every seven-
coordinated Cd(II) ion receives three pairs of bidentate
arylcarboxylate coordinations from three different metal-
loligands while the seventh coordination site is occupied
by a water molecule. Interestingly, crystal structure also
shows the presence of a Na(OH2)5 cluster which is held in
place by a series of H-bonds including Oamide and lattice
water molecules.
Application of HCNs in Heterogeneous Catalysis
An important structural feature of the four HCNs is the
utilization of two different types of metalloligands in the
construction of networks. Notably, metalloligand 1, offer-
ing six arylcarboxylate groups, affords quite densely-
packed HCNs 3 and 4. On the other hand, metalloligand
2, offering only three arylcarboxylate groups, generate
HCNs 5 and 6 with loosely packed architectures. Such
distinct architectures suggest that while HCNs 5 and 6
may allow facile diffusion of substrates and reagents due
to such a fact; other two HCNs may only interact with the
substrates and/or reagents on the surface. Therefore, the
four HCNs provide a good opportunity to compare their
role in the catalysis in order to understand the implica-
Solvent-accessible voids (SAVs) of different volumes
were found in all crystal structures. Networks 3 and 4 dis-
played SAVs of volume 1575.1 Å3 and 551.3 Å3 which corre-
spond to 29 % (5436.2 Å3) and 11.3 % (4863.0 Å3) of their
unit cell volumes, respectively. On the other hand, SAVs
of 1819.4 Å3 and 2543.3 Å3 corresponding to 19.3% (9445
Å3) and 25.3% (10046.3 Å3) of unit cell volume were noted
for networks 5 and 6, respectively.
ACS Paragon Plus Environment

Page 5 of 17
Crystal Growth & Design
networks have displayed noteworthy results by several
tion of design concept. Further, structural investigations
groups including us.49,51,75-85 The catalytic activities of
HCNs 3 – 6 was investigated by employing several aro-
matic and heterocyclic aldehydes using malononitrile as
an active methylene compound. In order to optimize the
reaction conditions; HCN 3 was used as a representative
catalyst for the KCs of benzaldehyde with malononitrile.
As can be seen from Table 3, catalyst 3 is essential for the
KC as no product was observed without it (entry 1). En-
tries 2 and 3 depict the importance of mild elevated tem-
perature of 50 oC for the quantitative conversion. It is fur-
ther noted that quantitative product formation requires
30 minutes (entry 4) and only 1-mol% catalyst loading
(entry 5). Entry 6 suggests that EtOH is the best solvent
for KCs as other solvents resulted in comparatively poor
performance. With these optimized reaction condition;
all four HCNs offered KCs of assorted aldehydic sub-
strates with malononitrile (Table 4). Importantly, only 1-
mol% of the four HCNs resulted in nearly quantitative
conversion for most of the substrates. Further, substrates
carrying either electron-withdrawing or electron-
donating groups (entries 2-4, Table 2); naphthyl group
(entry 5); and heterocyclic rings (entries 6 and 7) were
equally effective. These examples adequately illustrate the
importance of the present HCNs in carrying out the Lewis
acid metal assisted KCs heterogeneously and suggested
their potential catalytic roles in other similar reactions.
1
2
3
4
5
6
7
8
of all four HCNs illustrate the presence of Lewis acidic
metal ions, Zn(II) and Cd(II), arranged in an orderly
manner. Such secondary metal ions are coordinated by
the arylcarboxylate groups in addition to a certain num-
ber(s) of labile water molecules. Importantly, such labile
water molecules could be potentially displaced by the
suitable substrates (discussed below). Furthermore, 3D
nature of all HCNs, their stability and robustness, and
insolubility in common organic solvents provide an op-
tion to carry out the catalytic reactions heterogeneously.
We selected Knoevenagel condensation (KC) and cya-
nation reactions (CRs) of aldehydes to illustrate the im-
portance and uniqueness of the four HCNs.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Exchange Studies. One of the important parameters in
heterogeneous catalysis is to validate that the substrates
are able to replace loosely coordinated solvent mole-
cule(s) on a Lewis acidic metal ion. We selected HCN 3 to
provide such an evidence. In order to confirm whether
the coordinated and lattice water could be exchanged; 3
was heated under vacuum to remove most of the coordi-
nated and lattice water molecules. Such a dehydrated
sample was then saturated in a controlled environment of
D2O vapours. The FTIR spectrum of D2O-exchanged sam-
ple displayed shifted νO-D stretches at ca. 2500 cm-1 sug-
gesting replacement of the coordinated and lattice water
molecules (Figure S11, SI). Notably, other spectral features
did not show significant change confirming the frame-
work stability. Further, HCN 3 was impregnated with sub-
strate by suspending its crystals in a CH2Cl2 solution of
benzaldehyde and analysing with FTIR spectra, powder
diffraction, and scanning electron micrograph (SEM) im-
ages. The FTIR spectrum exhibited red-shifted νC=O
stretches (at 1680cm-1) for the impregnated C6H5CHO
when compared to neat sample (at 1700 cm-1) (Figure S12,
SI). Such a fact points out that benzaldehyde has been
potentially activated owing to its coordination to the Lew-
is acidic metal ion. On the other hand, powder XRD pat-
tern displayed broad and moderately shifted features in-
dicative of exchange (Figure S13, left panels; SI). Im-
portantly, SEM images display that the crystals retain
their shape and crystallinity albeit minor scars on the sur-
face (Figure S13, right panels; SI). Collectively, these stud-
ies show that the reagents (D2O and C6H5CHO) have the
potential to diffuse through the porous network and re-
place the coordinated water molecule(s).
Cyanation Reactions. CRs of carbonyl-based sub-
strates provide a convenient route to cyanohydrins which
are significant intermediates for a variety of fine chemi-
cals and organic synthons.86-89 Extensive research has
been directed to develop improved Lewis acid based cata-
lysts for the reaction of cyanide ion with carbonyl-based
substrates.90-93 In this context, heterogeneous catalysts
incorporating Lewis acidic sites are advantageous for the
ease in catalyst separation and product isolation.32-40,49,51
The successful performance of the present HCNs in KCs
advocated their potential role in CRs as well. As displayed
in Table 5, all four HCNs were able to catalyze CRs of as-
sorted aldehydes using trimethylsilylcyanide as the cya-
nide source. It is important to note that CRs reactions
were performed without any requirement of solvent tak-
ing advantage of liquid nature of most of the reagents.94
Benzaldehyde as well as several functionalized analogues
provided the corresponding cyanohydrins in good to ex-
cellent yield.
The CRs also provided the option to understand the
size exclusion catalysis as several related aldehydes with
varying molecular dimensions are available. We, there-
fore, performed CRs with assorted aldehydic substrates
differing in molecular dimensions as mentioned in Table
5. Importantly, benzaldehyde, 4-nitrobenzaldehyde, 4-
chlrobenzaldehyde, 4-methoxybenzaldehyde, and 3-
methoxybenzaldehyde offered very good to nearly quanti-
tative yield of the respective product with all four HCNs.
Such a fact suggests that these substrates have compara-
ble uncluttered access to the catalytic secondary metal
centers in all four HCNs. However, 1-naphthaldehyde and
2-naphthaldehyde as well as 9-anthraldehyde provided
Knoevenagel Condensation. Knoevenagel condensa-
tion73,74 (KC) is a well-known synthetic method for the
formation of C–C bonds needed for creating assorted or-
ganic synthons and significant classes of compounds. KCs
can be catalyzed by a variety of chemicals and reagents
whereas several Lewis acidic metals have also been suc-
cessfully utilized.75-85 Lewis acidic metals based heteroge-
neous catalysts stand out due to their potential reusabil-
ity, stability, and ease in product separation.49,51 However,
functional group tolerance and substrate scope has been
one of the limiting factors with heterogeneous catalysts
and therefore next-generation catalysts are required.32-40
In this context, Lewis acidic metal-based coordination
ACS Paragon Plus Environment

Crystal Growth & Design
Page 6 of 17
Supporting Information. Figures for the FTIR spectra, dif-
comparatively lower yield of the product especially with
HCNs 3 and 4. We reason that as the molecular size of the
substrate increases; more and more numbers of substrates
are excluded to approach the catalytic metal ions present
within the interior of the materials. Therefore, the catalyt-
ic sites available on the surface actually carry out the CR
as evidenced by the lower product yield. A notable differ-
ence is clearly observable between the HCNs produced by
metalloligand 1 when compared to the ones generated by
2. As already explained, both HCNs 5 and 6 offer much
larger pores and therefore less numbers of bulkier sub-
strates were excluded whereas densely packed HCNs 3
and 4 excluded maximum numbers of substrates. Such a
notable difference in catalysis is suggestive of the archi-
tectural distinctness between two categories of HCNs.
1
2
3
4
5
6
7
8
fuse reflectance absorption spectra, TGA, Powder XRD, and
SEM images; and Tables for the bond distances and bond
angles. This material is available free of charge via the Inter-
net at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*Fax: +91 – 11 – 27666605; Email: rgupta@chemistry.du.ac.in.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Present Addresses
†Department of Chemistry and Polymer Science
University of Stellenbosch,
Matieland 7602, South Africa
Author Contributions
Recyclability Experiments. As all four HCNs carried out
heterogeneous KCs and CRs quite efficiently; we became
interested to test the recyclability of these networks. Im-
portantly, addition of EtOAc to the reaction mixture re-
sulted in clean separation of HCNs. Such networks were
filtered, dried in air and were re-used for the subsequent
catalysis without any requirement of special treatment.
We tested the recovered HCNs for the KCs as well as CRs
for five consecutive cycles and did not notice any signifi-
cant decrease in the catalytic performance (Figure 5). All
four recovered networks were characterized by the pow-
der XRD measurements and gratifyingly showed alike
reflections to that of as-synthesized samples thus con-
firming that the structural integrity remains intact during
the catalysis (Figures 6 and S14 – S16, SI). The FTIR spec-
trum of recovered network 3 as a representative example
was also in excellent match to that of pristine sample
(Figure S17, SI). In order to understand the probable mor-
phological changes to the HCNs during the course of the
catalytic reaction; recovered network 3 was evaluated by
the SE micrographs (Figure 6). Although, SEM studies did
not show significant changes to the surface morphology
yet there were evidences of minor scars and cracks. These
studies further establish the reusable nature of the pre-
sent HCNs in Lewis acid assisted catalytic reactions.
The manuscript was written through contributions of all
authors.
ACKNOWLEDGMENT
RG acknowledges the financial support from the Science &
Engineering Research Board (SERB), New Delhi. Authors
sincerely thank CIF-USIC of the University of Delhi for the
instrumental facilities. SS acknowledges UGC for the SRF
fellowship.
REFERENCES
1. Kumar, G.; Gupta, R. Chem. Soc. Rev. 2013, 42, 9403.
2. Sessoli, R.; Powell, A. K. Coord. Chem. Rev. 2009, 253, 2328.
3. Kurmoo, M. Chem. Soc. Rev. 2009, 38, 1353.
4. 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.;
Coord. Chem. Rev. 2009, 253, 3042.
5. Rasappan, R.; Lanventine, D.; Reiser, O. Coord. Chem. Rev.
2008, 252, 702.
6. Maspoch, D.; Ruiz-Molina, D.; Veciana, J. Chem. Soc. Rev.
2007, 36, 770.
7. Chakrabarty, R.; Mukherjee, P. S.; Stang, P. J. Chem. Rev.
2011, 111, 6810.
8. Cook, T. R.; Stang, P. J. Chem. Rev. 2015, 0000; DOI:
10.1021/cr5005666.
9. Farha, O. K.; Hupp, J. T. Acc. Chem. Res. 2010, 43, 1166.
10. Chen, B.; Xiang, S.; Qian, G. Acc. Chem. Res. 2010, 43, 1115.
11. Pan, L.; Olson, D.H.; Ciemnolonski, L.R.; Heddy, R.; Li, J.
Angew. Chem. Int. Ed. 2006, 45, 616.
12. Li, J.R.; Kuppler, R.J.; Zhou, H.C. Chem. Soc. Rev. 2009, 38,
1477.
13. O’Kefee, M.; Yaghi, O. M. Chem. Rev. 2012, 112, 675.
14. Tranchemontagne, D.J.; Mendoza-Corte′, J.L.; O'Keeffe, M.;
Yaghi, O.M. Chem. Soc. Rev. 2009, 38, 1257.
15. Hu, Z.; Deibert, B. J.; Li, J. Chem. Soc. Rev. 2014, 43, 5815.
16. Kreno, L. E.; Leong, K.; Farha, O. K.; Allendorf, M.; Duyne,
R. P. V.; Hupp, J. T. Chem. Rev. 2012, 112, 1105.
17. Potyrailo, R. A.; Surman, C.; Nagraj, N.; Burns, A. Chem.
Rev. 2011, 111, 7315.
18. Brozek, C. K.; Dinca, M. Chem. Soc. Rev. 2014, 43, 5456.
19. Ramaswamy, P.; Wong, N. E.; Shimizu, G. K. H. Chem. Soc.
Rev. 2014, 43, 5913.
20. Sen, S.; Nair, N. N.; Yamada, T.; Kitagawa, H.; Bharadwaj,
P. K. J. Am. Chem. Soc. 2012, 134, 19432.
CONCLUSION
We have utilized two Co3+-based metalloligands with ap-
pended arylcarboxylic acid groups at the strategically
placed positions for the construction of {Co3+-Zn2+} and
{Co3+-Cd2+} heterometallic coordination networks. In the
resultant 3D networks, secondary Zn2+ and Cd2+ ions re-
ceive coordinations from the appended arylcarboxylate
groups of the metalloligands. These 3D networks exhibit
interesting network topologies including an unprecedent-
ed one. All networks acted as the heterogeneous and re-
usable catalysts for the Knoevenagel condensation reac-
tions and cyanation reactions of assorted aldehydes. The-
se examples adequately illustrate metalloligand strategy
for the development of promising heterometallic net-
works.
21. Sadakiyo, M.; Yamada, T.; Kitagawa, H. J. Am. Chem. Soc.
2014, 136, 13166.
22. Sadakiyo, M.; Yamada, T.; Kitagawa, H. J. Am. Chem. Soc.
2009, 131, 9906.
ASSOCIATED CONTENT
ACS Paragon Plus Environment

Page 7 of 17
Crystal Growth & Design
23. Hu, Z.; Deibert, B. J.; Li, J. Chem. Soc. Rev. 2014, 43, 5815.
24. Stavila, V.; Talin, A. A.; Allendorf, M. D. Chem. Soc. Rev.
2014, 43, 5994.
25. Wang, C.; Zhang, T.; Lin, W. Chem. Rev. 2012, 112, 1084.
26. Allendorf, M. D.; Bauer, C. A.; Bhaktaa, R. K.; Houka, R. J.
T. Chem. Soc. Rev. 2009, 38, 1330.
27. Bunzli, J. C. G.; Piguet, C. Chem. Rev. 2002, 102, 1897.
28. Cheng, X.N.; Zhang, W.X.; Lin, Y.Y.; Zheng, Y.Z.; Chen,
X.M. Adv. Mater. 2007, 19, 1494.
61. Spek, A.L.; PLATON, A Multipurpose Crystallographic
Tool, Utrecht University, The Netherlands, 2002.
62. Addition, A. W.; Rao, T. N.; Reedjik, J.; Van Rinj, J.;
Verschoor, G. C. J. Chem. Soc. Dalton Trans. 1984, 1349.
63. Blatov, V. A.; Shevchenko, A. P.; Serezhkin, V. N. J. Appl.
Crystallogr. 2000, 33, 1193.
64. Blatov, V. A.; O’Keefee, M.; Proserpio, D. M.
CrystEngComm. 2010, 12, 44.
65. Kim, J.; Chen, B.; Reineke, T. M.; Li, H.; Eddaoudi, M.;
Moler, D. B.; O’Keeffe, M.; Yaghi, O. M. J. Am. Chem. Soc. 2001,
123, 8239.
1
2
3
4
5
6
7
8
29. Wang, X.Y.; Wang, Z.M.; Gao, S. Chem. Commun. 2008,
281.
9
30. Deng, J.H.; Yuan, X.L.; Mei, G.Q. Inorg. Chem. Commun.
2010, 13, 1585.
31. Yang, Q.Y.; Li, K.; Luo, J.; Pan, M.; Su, C.Y. Chem. Commun.
2011, 47, 4234.
32. Ma, L.Q.; Abney, C.; Lin, W. Chem. Soc. Rev. 2009, 38,
1248.
33. Liu, J.; Chen, L.; Cui, H.; Zhang, J.; Zhang, L.; Su, C.-Y.
Chem. Soc. Rev. 2014, 43, 6011.
34. Dhakshinamoorthy, A.; Garcia, H. Chem. Soc. Rev. 2014,
43, 5750.
35. Corma, A.; Garcia, H.; Xamena, F. X. L. I. Chem. Rev. 2010,
110, 4606.
36. Lee, J. Y.; Farha, O. K.; Roberts, J.; Scheidt, K. A.; Nguyen,
S. B. T.; Hupp, J. T. Chem. Soc. Rev. 2009, 38, 1450.
37. Zhao, M.; Ou, S.; Wu, C.-D. Acc. Chem. Res. 2014, 47, 1199.
38. Horike, S.; Dinca, M.; Tamaki, K.; Long, J. R. J. Am. Chem.
Soc. 2008, 130, 5854.
39. Roberts, J. M.; Fini, B. M.; Sarjeant, A. A.; Farha, O. K.;
Hupp, J. T.; Scheidt, K. A. J. Am. Chem. Soc. 2012, 134, 3334.
40. Wang, C.; Zheng, M.; Lin, W. J. Phy. Chem. Lett. 2011, 2,
1701.
41. Ali, A.; Hundal, G.; Gupta, R. Cryst. Growth. Des. 2012, 12,
1308.
42. Kumar, G.; Aggarwal, H.; Gupta, R. Cryst. Growth. Des.
2013, 13, 74.
43. Mishra, A.; Ali, A.; Upreti, S.; Gupta, R. Inorg. Chem. 2008,
47, 154.
44. Mishra, A.; Ali, A.; Upreti, S.; Whittingham, M. S.; Gupta,
R. Inorg. Chem. 2009, 48, 5234.
45. Singh, A. P.; Gupta, R. Eur. J. Inorg. Chem. 2010, 4546.
46. Srivastava, S.; Ali, A.; Tyagi, A.; Gupta, R. Eur. J. Inorg.
Chem. 2014, 2113.
47. Singh, A. P.; Ali, A.; Gupta, R. Dalton Trans. 2010, 39, 8135.
48. Singh, A. P.; Kumar, G.; Gupta, R. Dalton Trans. 2011, 40,
12454.
49. Srivastava, S.; Dagur, M. S.; Gupta, R. Eur. J. Inorg. Chem.
2014, 4966.
50. Kumar, G.; Gupta, R. Inorg. Chem. Commun. 2012, 23, 103.
51. Bansal, D.; Hundal, G.; Gupta, R. Eur. J. Inorg. Chem. 2015,
1022.
66. Tranchemontagne, D. J.; Mendoza-Corte´, J. L.; O’Keeffe,
M.; Yaghi, O. M.; Chem. Soc. Rev., 2009, 38, 1257.
67. Shin, J. W.; Bae, J. M.; Kim, C.; Min, K. S. Inorg. Chem.
2013, 52, 2265.
68. Seth, P.; Bauza´, A.; Frontera, A.; Massera, C.; Gamez, P.;
Ghosh, A. CrystEngComm, 2013, 15, 3031;
69. Husain, A.; Ellwart, M.; Bourne, S. A.; Öhrström, L.; Oli-
ver, C. L. Cryst. Growth Des. 2013, 13, 1526;
70. Gong, Y.; Hao, Z.; Sun, J. L.; Shi, H.-F.; Jiang, P.-G.; Lin, J.-
H. Dalton Trans., 2013, 42, 13241;
71. Nasani, R.; Saha, M.; Mobin, S. M.; Martins, L. M. D. R. S.; J.
L. Pombeiro, A.; Kirillov, A. M.; Mukhopadhyay, S. Dalton
Trans., 2014, 43, 9944;
72. D’Vries, R. F.; Iglesias, M.; Snejko, N.; Gutiérrez-Puebla, E.;
Monge, M. A. Inorg. Chem., 2012, 51, 11349.
73. Freeman, F. Chem. Rev. 1980, 80, 329.
74. Tietze, L. F. Chem. Rev. 1996, 96, 115.
75. Lee, A.; Michrowska, A.; Sulzer-Mosse, S.; List, B. T. An-
gew. Chem. Int. Ed. 2011, 50, 1707.
76. Wei, Y. D.; Zhang, S. G.; Yin, S. F.; Zhao, C.; Luo, S. L.; Au,
C. T. Catal. Commun. 2011, 12, 1333.
77. Ikeue, K.; Miyoshi, N.; Tanaka, T.; Machida, M. Catal. Lett.
2011, 141, 877.
78. Brooks, A. C.; France, L.; Gayot, C.; Li, J.; Pui, H.; Sault, R.;
Stafford, A.; Wallis, J. D.; Stockenhuber, M. J. Catal. 2012, 285, 10.
79. Peng, Y.; Wang, J. Y.; Long, J.; Liu, G. H. Catal. Commun.
2011, 15, 10.
80. Postole, G.; Chowdhury, B.; Karmakar, B.; Pinki, K.;
Banerji, J.; Auroux, A. J. Catal. 2010, 269, 110.
81. Xu, D. Z.; Shi, S.; Wang, Y. RSC Adv. 2013, 3, 23075.
82. Kalbasi, R. J.; Mosaddegh, N. Catal. Commun. 2011, 12, 1231.
83. Merino, E.; Sesto, E. V.; Maya, E. M.; Iglesias, M.; Sánchez,
F.; Corma, A. Chem. Mater. 2013, 25, 981.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
84. Xu, D. Z.; Liu, Y. J.; Shi, S.; Wang, Y. M. Green Chem. 2010,
12, 514.
85. Li, G. W.; Xiao, J.; Zhang, W. Q. Green Chem. 2012, 14,
2234.
86. Gregory, R. J. H. Chem. Rev. 1999, 99, 3649.
87. Muller, U.; Schubert, M. M.; Yaghi, O. M. Handbook of
Heterogeneous Catalysis; Ed. Ertl, G.; Knozinger, H.; Schuth, F.;
Weitkamp, J. Wiley-VCH: Weinheim, Germany, 2008.
88. North, M. Tetrahedron: Asymmetry 2003, 14, 147.
89. Brunel, J. M.; Holmes, I. P. Angew. Chem. Int. Ed. 2004, 43,
2752.
90. Ryu, D. H.; Corey, E. J. J. Am. Chem. Soc. 2004, 126, 8106.
91. Keith, J. M.; Jacobsen, E. N. Org. Lett. 2004, 6, 153.
92. Hamashima, Y.; Kanai, M.; Shibasaki, M. J. Am. Chem. Soc.
2000, 122, 7412.
93. Baleizao, C.; Gigante, B.; Garcia, H.; Corma, A. Green
Chem. 2002, 4, 272.
94. In cases of solid substrates, addition of trimethylsilyl cya-
nide resulted in the formation of a slurry which was sufficient for
carrying out the reactions.
52. Kumar, G.; Gupta, R. Inorg. Chem. 2012, 51, 5497.
53. Kumar, G.; Gupta, R. Inorg. Chem. 2013, 52, 10773.
54. Kumar, G.; Kumar, G.; Gupta, R. Inorg. Chem. 2015, 54,
2603.
55. Perrin, D. D.; Armarego, W. L. F.; Perrin, D. R. Purification
of Laboratory Chemicals, Pergamon Press, Oxford, 1980.
56. Srivastava, S.; Gupta, R. Unpublished results (2015).
57. CrysAlisPro, Oxford Diffraction Ltd., version 1.171.33.49b
(2009).
58. Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A.
J. Appl. Crystallogr. 1993, 26, 343.
59. Sheldrick, G. M. Acta Crystallogr., Sec. A 2008, 64, 112.
60. Farrugia, L. J. WinGX version 1.70, An Integrated System of
Windows Programs for the Solution, Refinement and Analysis of
Single-Crystal X-ray Diffraction Data; Department of Chemistry,
University of Glasgow, 2003.
ACS Paragon Plus Environment

Crystal Growth & Design
Page 8 of 17
Table 1. Crystallographic Data Collection and Structure Refinement Parameters for Networks
3−6.
1
2
3
4
5
Network 3
Network 4
Network 5
Network 6
Molecular formula
C45H57CoN6O30Zn3 C84H90Co2N12O52Cd3 C78H74Co2N12Na2O31Zn2 C39H58CoN6NaO26Cd
6
Fw
T(K)
Crystal system
Space group
1388.78
293(2)
Monoclinic
P21/c
2510.42
293(2)
Monoclinic
P21/c
1943.86
293(2)
Monoclinic
C2/c
1186.97
293(2)
Monoclinic
C2/c
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
a
b
c
α
15.0290(4)
19.2206(6)
21.3862(11)
90
118.363(3)
90
5436.1(4)
4
1.697
2792
1.067
0.0417, 0.1117
0.0462, 0.1143
13.562(5)
17.989(5)
19.981(5)
90
93.910(5)
90
4863(3)
2
1.714
2496
1.084
0.0614, 0.1627
0.0690, 0.1676
1.06 and ꢀ2.08
17.317(5)
25.397(5)
21.540(5)
90
94.431(5)
90
9445(4)
4
1.367
3936
1.019
0.0797, 0.2294
0.0890, 0.2389
1.38 and ꢀ0.94
21.277(5)
24.814(5)
20.774(5)
90
113.662(5)
90
10046(4)
8
1.570
4752
1.036
0.0515, 0.1506
0.0608, 0.1576
1.34 and ꢀ0.60
β
γ
V (Å3)
Z
d (g cmꢀ3)
F (000)
Goodness of fit (F2)
R1, wR2 [I >2 (I)]
R1, wR2 [all data]a
Largest diff. peak 0.82 and ꢀ0.85
and hole (e Åꢀ3)
[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|; wR2 = {Σ[w(/Fo/ 2 – /Fc/ 2 )2]/Σ[wFo ]}1/2.
4
Table 2. Selected Bond Distances and Ranges for Networks 3 – 6.
Bond distance
Co(1)ꢀN(1)
3
4
5
6
1.933(3)
1.923(4)
1.933(5)
1.923(3)
Co(1)ꢀN(2)
Co(1)ꢀN(3)
Co(1)ꢀN(4)
Co(1)ꢀN(5)
Co(1)ꢀN(6)
1.929(3)
1.943(3)
1.953(3)
1.944(3)
1.936(3)
1.945(4)
1.954(4)
1.958(4)
1.943(4)
1.972(4)
1.958(5)
1.953(5)
1.957(4)
1.922(5)
1.930(5)
1.940(4)
1.944(3)
1.956(4)
1.964(4)
1.953(4)
MꢀOcarboxylate
MꢀOwater
1.941(3)ꢀ2.269(2) 2.173ꢀ2.573 1.951(5)ꢀ2.428(9) 2.262(6)ꢀ2.617(5)
2.017(3)ꢀ2.180(3) 2.220ꢀ2.450 ꢀꢀꢀ 2.266(5)
Where M = Zn2+ (for networks 3 and 5) and Cd2+ (for networks 4 and 6)
8
ACS Paragon Plus Environment

Page 9 of 17
Crystal Growth & Design
1
2
3
Table 3. Control experiments for the Knoevenagel condensation of benzaldehyde with malonoꢀ
nitrile using network 3.
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Entry Catalyst [molꢀ%]
Solvent
Time [min] Temp. [°C]
Yield [%]a
0
1
2
3
4
5
6
Ethanol
60
30
25
ꢀ
3 [1]
Ethanol
25
40, 50, 60
50
70
3 [1]
Ethanol
Ethanol
30
80, 100, 100
85, 100
3 [1]
15, 30
30
3 [0.5, 1, 2]
3 [1]
Ethanol
50
75, 100, 100
85, 82, 78, 80
MeOH, CH3CN, EtOAc, Toluene
30
50
aYield was calculated using the gas chromatograph.
9
ACS Paragon Plus Environment

Crystal Growth & Design
Page 10 of 17
1
2
3
Table 4. Knoevenagel condensation of assorted aldehydes using networks 3 – 6.
4
5
6
7
8
9
Entrya
R
Product
Yield [%]b
Network 4 Network 5
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Network 3
Network 6
CN
CN
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
>99
99
1
2
3
4
5
6
C6H5
CN
CN
>99
>99
99
4ꢀNO2C6H4
4ꢀClC6H4
O2N
CN
CN
Cl
CN
CN
CN
CN
3ꢀMeOC6H4
Naphthalenꢀ2ꢀyl
Furanꢀ2ꢀyl
MeO
99
99
99
99
CN
CN
O
S
99
>99
>99
99
CN
CN
7
Thiophenꢀ2yl
aConditions: Catalyst: 1ꢀmol%; solvent: EtOH; Temperature: 50 °C; Time: 30 min. Yield was calculated using the gas
b
chromatograph.
10
ACS Paragon Plus Environment

Page 11 of 17
Crystal Growth & Design
1
2
3
Table 5. Cyanation reactions of assorted aldehydes with trimethylsilylcyanide using HCNs 3 – 6.
4
5
6
7
Entrya
Substrate
Molecular drawing of
the substrate
Molecular dimension of
Yield [%]b
substrate (l × w × h)
8
9
3
4
5
6
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1
90
92
98
>99
4.2 × 6.03 × 1.4
4.22 × 6.98 × 1.4
2
95
96
99
>99
3
4
5
6
78
80
78
40
85
87
80
50
99
94
90
80
99
94
92
88
4.21 × 6.68 × 2.0
4.20 × 8.47 × 2.06
4.85 x 7.77 x 2.10
6.03 × 6.64 × 1.4
7
8
36
38
45
45
78
40
85
55
5.66 × 7.21 × 1.4
6.22 × 9.28 × 1.4
aConditions: Catalyst: 1ꢀmol%; solvent: EtOH; Temperature: 50 °C; Time: 30 min. Yield was calculated using the gas
chromatograph.
b
11
ACS Paragon Plus Environment

Crystal Growth & Design
Page 12 of 17
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 1. (a) Asymmetric unit of network 3; thermal ellipsoids are drawn at 30% probability level
whereas hydrogen atoms, isopropyl alcohol and water molecules are omitted for clarity. (b) Ball and
Stick representation of a selected part of the crystal structure of network 3. Color code: sea green, Co;
gold, Zn; blue, N; green, Ocarboxylate; violet, Owater; red, Oamide; gray, C. (c) Extended structure of network
3. (d) Extended structure of network 3 along the a axis showing the presence of isopropyl alcohol
(spaceꢀfill mode; purple color) within the network lattice. (e) Topological representation of network 3.
Color code: green, Co; yellow, Zn; gray, contribution from the ligand.
12
ACS Paragon Plus Environment

Page 13 of 17
Crystal Growth & Design
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 2. (a) Asymmetric unit of network 4; thermal ellipsoids are drawn at 30% probability level
whereas hydrogen atoms and water molecules are omitted for clarity. (b) Ball and Stick representation
of a selected part of the crystal structure of network 4. Color code: sea green, Co; gold, Cd; blue, N;
green, Ocarboxylate; violet, Owater; red, Oamide; gray, C. (c) Extended structure of network 4. (d) Extended
structure of network 4 in a view along the a axis. (e) Topological representation of network 4. Color
code: green, Co; yellow, Cd; gray, contribution from the ligand.
13
ACS Paragon Plus Environment

Crystal Growth & Design
Page 14 of 17
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 3. (a) Asymmetric unit of network 5; thermal ellipsoids are drawn at 30% probability level
whereas hydrogen atoms, Na+ ion and water molecules are omitted for clarity. (b) Ball and Stick repreꢀ
sentation of a selected part of the crystal structure of network 5. Color code: sea green, Co; gold, Zn;
blue, N; green, Ocarboxylate; violet, Owater; red, Oamide; gray, C. (c) Extended structure of network 5. (d) Exꢀ
tended structure of network 5 in a view along the a axis. (e) Topological representation of network 5.
Color code: green, Co; yellow, Zn.
14
ACS Paragon Plus Environment

Page 15 of 17
Crystal Growth & Design
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
Figure 4. (a) Asymmetric unit of network 6; thermal ellipsoids are drawn at 30% probability level
whereas hydrogen atoms, Na+ ion, and water molecules are omitted for clarity. (b) Ball and Stick repreꢀ
sentation of a selected part of the crystal structure of network 6. Color code: sea green, Co; gold, Cd;
blue, N; green, Ocarboxylate; violet, Owater; red, Oamide; gray, C. (c) Packing diagram of network 6. (d) Exꢀ
tended structure of network 6 in a view along the c axis. (e) Topological representation of network 6.
Color code: green, Co; yellow, Cd.
53
54
55
56
57
58
59
60
15
ACS Paragon Plus Environment

Crystal Growth & Design
Page 16 of 17
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 5. Recycling of network 3 up to five cycles in the Knoevenagel condensation reactions (red bars)
and the cyanation reactions (green bars).
Figure 6. PXRD patterns along with the SEM images of network 3; before (left panel) and after the
Knoevenagel condensation reaction of benzaldehyde with malononitrile (right).
16
ACS Paragon Plus Environment

Page 17 of 17
Crystal Growth & Design
1
2
3
4
5
6
7
For Table of Contents Use Only
Threeꢀdimensional Heterometallic Coordination Networks: Syntheses, Crystal Structures,
Topologies and Heterogeneous Catalysis
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Sumit Srivastava, Himanshu Aggarwal,† and Rajeev Gupta*
Synopsis and Artwork
This work shows the utilization of two unique Co3+-based metalloligands offering appended arylcarboxylic acid
groups at the strategically placed positions for the construction of {Co3+-Zn2+} and {Co3+-Cd2+} heterometallic coor-
dination networks. The networks display orderly arrangement of secondary metal ions and interesting network to-
pologies. These networks function as the heterogeneous and reusable catalysts for the Knoevenagel condensation
and cyanation reactions of assorted aldehydes.
17
ACS Paragon Plus Environment