Cobalt(II) and silver(I) coordination polymers constructed from flexible bis(5,6-dimethylbenzimidazole) and substituted isophthalate co-ligands

Article abstract of DOI:10.1007/s11243-014-9829-6

Two coordination polymers, [Co(L1)(IPA] _n (1) and {[Ag(L2)(HMIPA)]·H₂O} _n (2) (H₂IPA = isophthalic acid, L1 = 1,2-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H₂MIPA = 5-methylisophthalic acid, L2 = 1,6-bis(5,6- dimethylbenzimidazol-1-yl)hexane, have been synthesized and characterized by physicochemical and spectroscopic methods, as well as single-crystal X-ray diffraction. In 1, six-coordinated cobalt centers are bridged by L1 and IPA ^2- ligands to generate a (4,4) two-dimensional layer. However, complex 2 features a 1D chain structure, which is further extended by O-H···O hydrogen bonding interactions into a 2D supramolecular layer with (6³) topology. The fluorescence and thermal gravimetric analysis of both complexes were also explored. Furthermore, the complexes 1 and 2 exhibit remarkable catalytic properties for the degradation of methyl orange dyes in a Fenton-like process.

Full text of DOI:10.1007/s11243-014-9829-6

Transition Met Chem
DOI 10.1007/s11243-014-9829-6
Cobalt(II) and silver(I) coordination polymers constructed
from flexible bis(5,6-dimethylbenzimidazole) and substituted
isophthalate co-ligands
•
Rui Yang Kristof Van Hecke Bao Yi Yu
•
•
•
Guang Yue Li Guang Hua Cui
Received: 4 March 2014 / Accepted: 15 April 2014
Ó Springer International Publishing Switzerland 2014
Abstract Two coordination polymers, [Co(L1)(IPA]n (1)
and {[Ag(L2)(HMIPA)]ꢀH2O}n (2) (H2IPA = isophthalic
acid, L1 = 1,2-bis(5,6-dimethylbenzimidazol-1-ylmethyl)
benzene, H2MIPA = 5-methylisophthalic acid, L2 =
1,6-bis(5,6-dimethylbenzimidazol-1-yl)hexane, have been
synthesized and characterized by physicochemical and
spectroscopic methods, as well as single-crystal X-ray dif-
fraction. In 1, six-coordinated cobalt centers are bridged by
L1 and IPA2- ligands to generate a (4,4) two-dimensional
layer. However, complex 2 features a 1D chain structure,
which is further extended by O–HꢀꢀꢀO hydrogen bonding
interactions into a 2D supramolecular layer with (63) topol-
ogy. The fluorescence and thermal gravimetric analysis of
both complexes were also explored. Furthermore, the com-
plexes 1 and 2 exhibit remarkable catalytic properties for the
degradation of methyl orange dyes in a Fenton-like process.
construction of novel MOCPs depends on several factors, such
as metal–ligand ratio, choice of solvents, pH of the solution,
temperature, diversity of the ligands and possible supramolec-
ular interactions [6–12]. Among these factors, N-donor ligands
play a key role in the design and construction of such coordi-
nation polymers. The flexible bis(5,6-dimethylbenzimidazole)
ligands have been given more and more attention by our and
other groups [13–17], due to their strong coordinationability and
the flexibility of the –(CH2)n– or –(Ph–CH2)n– spacer, which
allow the ligands to bend and rotate in order to conform to the
coordination geometries of the metal atoms and consequently
generate more robust and intricate networks. Moreover, 5,6-
dimethylbenzimidazole can serve as an axial ligand for cobalt in
the biosynthesis of vitamin B12 [18, 19]. In addition, aromatic
polycarboxylates are excellent building units, and especially
isophthalic acid and its derivatives serve as good candidates
because of their various coordination modes [20–24]. The
employment of mixed ligands of N-containing groups and
dicarboxylates can compensate the charge balance, coordination
deficiency, and weak interactions all at once, which enriches
further the versatility of coordination complexes [25]. As a part
of our continuing work on ternary metal complexes based on
flexible bis(5,6-dimethylbenzimidazole) derivative and car-
boxylic acid ligands, herein, we report the syntheses and char-
acterization of two new MOCPs, namely [Co(L1)(IPA)]n (1)
and {[Ag(L2)(HMIPA)]ꢀH2O}n (2). Their thermal stabilities,
luminescent and catalytic properties were investigated.
Introduction
In recent years, the rational design and synthesis of metal–
organic coordination polymers (MOCPs) have received many
researchers’ attention, not least because of the profuse structures
and fascinating topologies, but also for their potential applica-
tions as functional materials in catalysis, luminescence,
magnetism and gas absorption [1–5]. It is well known that
R. Yang ꢀ G. Y. Li ꢀ G. H. Cui (&)
College of Chemical Engineering, Hebei United University,
46 West Xinhua Road, Tangshan 063009, Hebei,
People’s Republic of China
Experimental
e-mail: tscghua@126.com
Materials and measurements
K. Van Hecke ꢀ B. Y. Yu
All the reagents and solvents used for the synthesis were
commercially available and used directly without further
Department of Inorganic and Physical Chemistry, Ghent
University, Krijgslaan 281 S3, 9000 Ghent, Belgium
123

Transition Met Chem
Table 1 Crystallographic data for 1 and 2
N
N
N
N
N
N
N
N
Complex
1
2
Empirical formula
Formula weight
C34H30CoN4O4
617.55
C33H38AgN4O5
678.54
L2
CH3
L1
˚
Wavelength/A
0.71073
0.71073
Triclinic
P¯ı
Crystal system
Space group
Monoclinic
P21/c
Unit cell dimensions
HOOC
HOOC
COOH
COOH
˚
a/A
10.3963(11)
16.6902(19)
17.1741(19)
11.5143(12)
11.8139(12)
13.5056(14)
64.7510(10)
81.7810(10)
87.4000(9)
1644.3(3)
2
H2MIPA
H2IPA
˚
b/A
˚
c/A
Scheme 1 Ligands L1, L2, H2IPA and H2MIPA
a/°
b/°
c/°
99.864(2)
3
˚
purification. The ligands L1 and L2 were synthesized
according to a previously reported literature method [26]
(Scheme 1). IR data were recorded on an Avatar 360
(Nicolet) spectrophotometer with KBr pellets in the region
of 4,000–400 cm-1. Elemental analyses of C, H and N
were carried out on a Perkin-Elmer 240C automatic ana-
lyzer. Thermal analyses were performed on a Netzsch TG
209 thermal analyzer from room temperature to 800 °C
under nitrogen atmosphere with a heating rate of
10 °C min-1. The luminescence spectra for the powdered
solid samples were measured at room temperature on a
Hitachi F-7000 fluorescence spectrophotometer.
V/A
2935.9(6)
4
Z
Dc/gꢀcm-3
F(000)
1.397
1,284
1.370
702
Crystal size/mm
h range/°
Reflections collected
0.28 9 0.24 9 0.13 0.25 9 0.22 9 0.19
1.71–27.58
17,777
1.68–26.00
9,057
Independent reflections 6,755
Rint 0.0593
6,337
0.0152
0.657
Absorption coefficient/ 0.631
mm-1
T/K
293(2)
293(2)
Goodness of fit on F
0.978
1.085
Synthesis of the [Co(L1)(IPA)]n (1)
Final R, wR2
[I [ 2r(I)]a,b
R (all data)a,b
R1 = 0.0483
wR2 = 0.0974
R1 = 0.1044
wR2 = 0.1183
0.960, -0.284
R1 = 0.0422
wR2 = 0.1210
R1 = 0.0508
wR2 = 0.1263
1.524, -0.800
A mixture of Co(OAc)2ꢀ4H2O (24.9 mg, 0.1 mmol), L1
(39.4 mg, 0.1 mmol), H2IPA (16.6 mg, 0.1 mmol) and
H2O (15 mL) was sealed in a 25 mL Teflon-lined stainless
vessel and heated to 140 °C for 3 days under autogenous
pressure. Afterward, the autoclave was cooled down to
room temperature at a rate of 5 °C/h. Purple block-shaped
crystals of 1 were isolated with a yield of 52 % (based on
Co(OAc)2ꢀ4H2O). Calcd. for C34H30CoN4O4 (Fw =
617.55): C 66.1, H 4.9, N 9.1 %; found: C 65.8, H 5.1, N
9.4 %. FTIR (KBr pellet, cm-1): 3,116 w, 2,930 w,
1,613 s, 1,563 s, 1,513 s, 1433 s, 1,385 s, 1,060 m, 952 w,
832 w, 735 s.
Largest diff. peak and
hole
a
R1 = R ||Fo| - |Fc||/R |Fo|
wR2 = {R [w(F2o - F2c)2]/R [w(Fo2)2]}1/2
b
58.5, H 5.9, N 8.6 %. FTIR(KBr pellet, cm-1): 3,501 s,
2,852 m, 1,679 s, 1,505 s, 1,385 m, 1,205 s, 832 m,
772 m, 676 m.
Catalysis experiments
Synthesis of the {[Ag(L2)(HMIPA)]ꢀH2O}n (2)
The catalytic performance of complexes 1 and 2 was inves-
tigated in terms of the degradation of methyl orange,
according to a typical process [27]. The catalytic degradation
experiments were carried out with 150 mL (10 mg/L) methyl
orange solution (the pH was adjusted to 3.0 by dropwise
addition of 0.1 mol/L H2SO4), 50 mg of the required complex
and 30 mg sodium persulfate. The experimental temperature
was maintained at 30 °C, under constant stirring. The dye
concentrations were measured spectrophotometrically at
The synthetic procedure for 2 was analogous to the syn-
thesis of 1: a solution of AgOAc (16.7 mg, 0.1 mmol), L2
(17.8 mg, 0.1 mmol), H2MIPA (17.8 mg, 0.1 mmol) and
H2O (15 mL) was stirred for 0.5 h. Colorless block-shaped
crystals of complex 2 suitable for X-ray diffraction were
collected by mechanical separation from an amorphous
solid in 25 % yield based on AgOAc. Calcd. for C33H38
AgN4O5 (Fw = 678.54): C 58.4, H 5.6, N 8.3 %; found: C
123

Transition Met Chem
˚
Results and discussion
Table 2 Selected bond lengths (A) and angles (°) for 1 and 2
Parameter
Value
Parameter
Value
Synthesis, IR spectra of complexes 1 and 2
[Co(L1)(IPA)]n
Co1–O2
2.0194(18)
2.066(2)
2.0736(18)
2.097(2)
2.253(2)
2.390(2)
99.03(9)
154.25(9)
101.57(8)
91.52(8)
97.34(8)
O2–Co1–O4A
N3–Co1–O4A
O3A–Co1–O4A
N1–Co1–O4A
O2–Co1–O1
N3–Co1–O1
O3A–Co1–O1
N1–Co1–O1
O4A–Co1–O1
N3–Co1–N1
95.18(8)
157.76(8)
60.80(7)
90.31(8)
58.82(7)
86.13(8)
107.31(7)
149.70(8)
86.71(7)
106.24(9)
Both complexes were synthesized by the hydrothermal
method in a H2O system, in which the metal salt, the
corresponding organic acid and the N-donor ligand were
present in a molar ratio of 1:1:1. The strong and broad peak
around 3,501 cm-1 for 2 corresponds to the O–H stretching
vibration modes of the water ligand. The peaks at
1,505–1,513 cm-1 of both complexes may be attributed to
Co1–N3
Co1–O3A
Co1–N1
Co1–O4A
Co1–O1
O2–Co1–N3
O2–Co1–O3A
N3–Co1–O3A
O2–Co1–N1
O3A–Co1–N1
m
C=N of benzimidazole bands of the L1 and L2 ligands. The
separation of the asymmetric and symmetric stretching
vibrations of IPA2- was 180 (mas(C–O), 1,613 and msym
(C–O) 1,433 cm-1), indicating a bidentate coordination
mode of the carboxylate to the metal atom [31]. A strong
absorption band at 1,679 cm-1 for –COOH is observed for
2, which indicates that the carboxyl groups of the organic
moieties are incompletely deprotonated [32].
{[Ag(L2)(HMIPA)]ꢀH2O}n
Ag1–N1
Ag1–N3
Ag1–O1
2.124(3)
N1–Ag1–N3
N1–Ag1–O1
N3–Ag1–O1
152.45(11)
111.01(10)
94.07(10)
2.137(3)
2.551(3)
Symmetry transformation used to generate equivalent atoms for 1:
A = x, -y ? 1/2, z - 1/2
Crystal structure of complex 1
Single-crystal X-ray diffraction analysis reveals that 1
crystallizes in the monoclinic space group P21/c. The
asymmetric unit of 1 contains one Co(II) atom, one L1 and
one IPA2- ligands. Each Co atom is hexa-coordinated,
exhibiting a distorted octahedral geometry as shown in
Fig. 1a. Each Co1 center is coordinated by two nitrogen
atoms from two L1 ligands and four oxygen atoms from two
IPA2- anions. The N3, O2, O3A and O4A atoms comprise
the equatorial plane (symmetry code: A: x, -y ? 1/2,
z - 1/2), and the two apical sites are occupied by the N and
O1 atoms. The Co–N bond distances are 2.097(2) (Co1–N1)
506 nm. This procedure was repeated in the absence of the
complex as a blank comparison experiment. The degradation
efficiency of methyl orange is defined as follows [28]:
ðC0 ꢁ CtÞ
Degradation efficiency ¼
ꢂ 100%
C0
where C0 (mg/L) is the initial concentration of methyl
orange, and Ct (mg/L) is the concentration of methyl
orange at reaction time t (min).
˚
and 2.066(2) A (Co1–N3), and the Co–O bond distances
X-ray crystallography
˚
range from 2.019(2) to 2.390(2) A, which are comparable to
Single-crystal X-ray diffraction data for both complexes
were collected on a Bruker Smart 1000 CCD diffractom-
those of related cobalt complexes [33].
In 1, the Co(II) atoms are connected by L1 ligands with
a l2-bridging mode to form a 1D zigzag chain (Fig. 1b).
Neighboring 1D chains are further extended by IPA2- with
l2–g2, g2 coordination modes into a 2D layered structure.
As shown in Fig. 1c, quadrangular [Co(L1)(IPA)] units can
be distinguished, with their vertices occupied by four
Co(II) atoms and their four sides consisting of two L1
ligands and two anionic IPA. The side lengths are
˚
eter with Mo Ka radiation (k = 0.71073 A) at room tem-
perature by x and h scan modes. All absorption corrections
were applied using the SADABS program [29]. The two
structures were solved by direct methods and refined on F2
by full-matrix least-squares techniques using the Bruker
SHELXTL program package [30]. The non-hydrogen
atoms were refined with anisotropic displacement param-
eters. The hydrogen atoms of all water molecules could be
located from a difference Fourier map, while the other
hydrogen atoms were included in calculated positions and
refined with isotropic thermal parameters riding on the
corresponding parent atoms. The crystal parameters, data
collection and refinement results for complexes 1 and 2 are
summarized in Table 1. Selected bond lengths and angles
are listed in Table 2.
2-
˚
10.516(5) and 8.766(4) A, for the L1 and IPA ligands,
respectively. From a topological perspective, when the
Co(II) atom is regarded as a 4-connected node, L1 ligands
and IPA2- dianions can be considered as connectors, and
hence, the layer can be described as a 4-connected 2D (4,4)
network with (44ꢀ62) topology (Fig. 1d). Furthermore, p–p
stacking interactions are observed (centroid-to-centroid
˚
distance of 3.601(2) A) between the imidazole rings of the
123

Transition Met Chem
(a)
(c)
(b)
(d)
Fig. 1 a Coordination environment around the Co atom in 1, all
hydrogen atoms were omitted for clarity. (Symmetry codes: A : x,
-y ? 1/2, z - 1/2. B : -x ? 1, y ? 1/2, -z ? 3/2); b View of the
1D chain constructed by L1 ligands and Co(II) ions; c View of the 2D
supramolecular framework (methyl groups were omitted for clarity);
d Topological view of the {44ꢀ62} network in 1
adjacent L1 ligands (Cg: N3–C11–C18–N14–C19), which
additionally enhances the stability of the 2D network.
In 2, the HMIPA- acts as a terminal ligand to the
Ag(I) center, giving a neutral [Ag(HMIPA)] subunit. The
neighboring subunits are bridged by L2 ligands to generate a
1D zigzag infinite chain structure (Fig. 2b). Each L2 ligand
adopts the anti-configuration in which the benzimidazole
rings within each unit are parallel, and the Ag1–AgA and
Crystal structure of complex 2
Complex 2 crystallizes in the triclinic P¯ı space group and
exhibits a 1D coordination structure. The asymmetric unit of
2 consists of one Ag(I) ion, one HMIPA- anion, one
L2 ligand and one uncoordinated water solvent molecule.
Figure 2a depicts the coordination environment of the
Ag(I) center, showing that it is coordinated by two nitrogen
˚
Ag1–AgB distances are 12.871(9) and 12.976(8) A, respec-
tively (symmetry codes: A: -x, -y, -z ? 1, B: -x ? 1,
-y ? 1, -z ? 2). Furthermore, there are two kinds of
O–HꢀꢀꢀO hydrogen bond interactions (O1WꢀꢀꢀO4C = 2.830
˚
(5) A, O1W–H1 WBꢀꢀꢀO4C = 180(2)°, O1WꢀꢀꢀO3D = 2.842
˚
atoms from two distinct L2 ligands (Ag1–N1 = 2.124(3) A
˚
(6) A, O1W–H1WAꢀꢀꢀO3D = 149(6)°, symmetry codes: C:
˚
and Ag1–N3 = 2.137(3) A) and one oxygen atom from a
x ? 1, y ? 1, z - 1, D: -x ? 1, -y ? 1, -z ? 2) between
the uncoordinated lattice water molecule and symmetry-
equivalent HMIPA- anions, resulting in a 2D supermolecule
structure (Fig. 2c), which is a common network with (63)
topology (Fig. 2d). Interestingly, there are two types of p–p
HMIPA- dianion (Ag1–O1 = 2.551(3) A), giving a dis-
˚
torted T-shaped geometry (N1–Ag1–N3 = 152.45(11)°,
N3–Ag1–O1 = 94.07(10)°). Both distances of the Ag–N
and Ag–O are within acceptable ranges [34, 35].
123

Transition Met Chem
Fig. 2 a Coordination environment around the Ag(I) ion in 2, all
hydrogen atoms were omitted for clarity. (Symmetry codes: A : -x,
-y, -z ? 1, B : -x ? 1, -y ? 1, -z ? 2); b 1D zigzag chain of 2
(Symmetry codes: A : -x, -y, -z ? 1, B : -x ? 1, -y ? 1,
-z ? 2); c 2D supramolecular network formed by O–HꢀꢀꢀO hydrogen
bond interactions for 2; d Topological view of the {63} network in 2
Thermal analysis
The thermogravimetric analysis experiments of complexes
1 and 2 were investigated under N2 atmosphere, using a
temperature gradient from room temperature to 800 °C at a
rate of 10 °C/min. As shown in Fig. 3, the TG curve of
complex 1 can be divided into two major steps. Complex 1
remains stable up to 260 °C, then weight loss occurs in the
range of 260–477 °C, which corresponds to the release of
ligand L1 (calcd: 63.6 %, found: 63.2 %). The weight loss
from 573 to 727 °C can be attributed to the release
of IPA2- ligands (calcd: 24.3 %, found: 24.6 %). The
remaining residue corresponds to CoO, which has been
formed (calcd: 12.1 %, found: 12.2 %). Complex 2, how-
ever, shows three steps in the TG curve. Firstly, the water
molecules are lost from 104 to 129 °C (calcd: 2.6 %,
found: 2.5 %). Secondly, the weight loss, which occurs
from 213 to 276 °C, is consistent with the loss of HMIPA-
ligands (calcd: 26.4 %, found: 26.7 %). Thirdly, the weight
loss observed from 303 to 460 °C can be assigned to the
decomposition of L2 ligands (calculated: 53.9 %, found:
54.1 %). The remaining weight corresponds to Ag2O
(calcd: 17.1 %, found: 16.7 %).
Fig. 3 TG curves for complexes 1 and 2
stacking interaction between the benzimidazole rings of the
L2 ligands, i.e., the centroid-to-centroid distances range
˚
from 3.672(3) to 3.758(5) A (Cg1–Cg3, Cg2–Cg4, respec-
tively), and the inter-planar angles a vary from 1.5(2) to
1.7(2)° (Cg1: N1–C1–N2–C2–C9, Cg2: N3–C22–N4–C30–
C23, Cg3: C2–C3–C4–C6–C8–C9 and Cg4: C23–C24–
C25–C27–C29–C30).
123

Transition Met Chem
Fig. 5 Degradation experiment results
Fig. 4 Solid-state photoluminescence emission spectra of the free
ligands L1, L2 and complexes 1, 2
of SO:4ꢁ, and hence, because of its strong oxidizing
properties, can be used to resolve organic pollutants. As
previously reported, transition metal coordination polymers
can possess good catalytic properties in a Fenton-like
process [41].
Photoluminescence properties
The photoluminescence properties of 1, 2 and free N-donor
ligands L1 and L2 in the solid state at room temperature
have been measured. As illustrated in Fig. 4, the free
ligands L1 and L2 exhibit emission peaks at 346 and
362 nm with excitations at 298 and 320 nm, respectively.
The fluorescence peaks at about 381 nm for 1 and 380 nm
for 2 are found in the emission spectra upon excitation at
210 nm for both complexes. Compared with the free L1
and L2 ligands, the emission maxima of 1 and 2 are
obviously red-shifted. For 1, this might be attributed to the
coordination between ligands and metal atoms. For 2, this
may come from the electronic transition between the p
orbitals (filled orbitals) of coordinated N atoms and the 5 s
orbital (empty orbital) of the Ag(I) center, i.e., ligand-to-
metal charge transfer (LMCT), mixed with metal-centered
(d–s/d–p) transitions [36]. In addition, the carboxylate
ligands show very weak n–p transitions; hence, it can be
considered that the carboxylate ligands do not significantly
contribute to the fluorescence emission of the coordination
polymers when N-donor ligands are present [37].
In this experiment, methyl orange was selected as a
model compound, considering organic pollutants. The
results of the degradation of methyl orange are depicted in
Fig. 5. As is shown, when the experiment was conducted as
a blank comparison test, after 150 min the degradation
efficiency was only 18.2 %, indicating that methyl orange
cannot be effectively oxidized by persulfate solely. How-
ever, when adding complex 1 or 2 as catalyst, the color of
the methyl orange was visibly removed. The degradation
efficiency of the methyl orange degradation within 30 min
reaction was about 30 % in the presence of 1 and reached
to approximately 60 % after 150 min. In comparison with
the two above reactions, the degradation rate of the methyl
orange solution increased significantly when applying 2 as
the catalyst. After 150 min, the final degradation efficiency
amounted up to even 90 %. Clearly, under the same con-
ditions, the catalytic activity of 2 is higher than that of 1.
Compared with the blank comparison experiment, both of
the complexes have a prominent effect on the degradation
of methyl orange.
Catalytic degradation experiments
It is possible to represent the degradation mechanism,
according to Eqs. (1–6), respectively.
Azo dyes have been widely used in textile, printing, food,
pharmaceutical and research laboratories because of their
chemical stability and versatility [38, 39]. Most of them are
non-biodegradable, toxic and potentially carcinogenic in
nature. To speed up the rate of degradation, Fenton-like
processes have attracted the attention of many researchers
[40]. A Fenton-like process is performed under the pre-
sence of catalyst and a peroxydisulfate S2O82-, which is
considered an effective oxidant system for the production
For 1:
CoII ꢁ MOF þ S2O82ꢁ ! CoIII ꢁ MOF þ SO42ꢁ
þ SO:4ꢁ
ð1Þ
CoIII ꢁ MOF þ S2O82ꢁ ! CoII ꢁ MOF þ SO4:ꢁ
ð2Þ
ð3Þ
Dye þ SO:4ꢁ ! oxidation products
For 2:
123

Transition Met Chem
AgI ꢁ MOF þ S2O28ꢁ ! AgII ꢁ MOF þ SO24ꢁ þ SO4:ꢁ
ð4Þ
8. Pu AT, Yang J, Kan WQ, Yang Y, Ma JF (2013) Polyhedron
50:556–570
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Growth Des 10:1946–1959
AgII ꢁ MOF þ S2O28ꢁ ! AgI ꢁ MOF þ SO:4ꢁ
Dye þ SO:4ꢁ ! oxidation products.
ð5Þ
ð6Þ
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(2013) Chem Commun 49:871–873
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Russ J Coord Chem 38:55–60
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Met Chem 38:359–365
Conclusion
In summary, two MOCPs, based on flexible bis(5,6-
dimethylbenzimidazole) and two kinds of benzenedicar-
boxylate with different substituent groups, have been
synthesized under hydrothermal conditions. Complex 1
displays a 2D (4,4) network, while in complex 2, the 1D
zigzag infinite chains are converted into a 2D supramo-
lecular layer via O–HꢀꢀꢀO interactions. The structural ana-
lysis results reveal that metal ions and the supramolecular
interactions such as hydrogen bonding interactions play an
important role in governing the molecular architectures. In
addition, the Ag(I) complex exhibits a higher catalytic
activity for the degradation of a methyl orange dye in a
Fenton-like process than the Co(II) complex.
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Acknowledgments KVH thanks the Hercules Foundation (project
AUGE/11/029 ‘‘3D-SPACE: 3D Structural Platform Aiming for
Chemical Excellence’’) for funding.
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