Construction of homo- and heterometallic-pyridine-2,3-dicarboxylate metallosupramolecular networks with structural diversity: 1D T5(2) water tape and unexpected coordination mode of pyridine-2,3-dicarboxylate

Article abstract of DOI:10.1039/c2ce26675j

Five new homo and heterometallic Cu(ii), Cd(ii), Cu(ii)-Ag(i), Cu(ii)-Cd(ii) supramolecular networks with pyridine-2,3-dicarboxylate (pydc), {[Cu(μ-pydc)(dmpen)₂]}_n (1), [Cu₂(μ-pydc) ₂(emim)₄]·2H₂O (2), [Cd(μ-pydc)(emim) ₂]_n (3), [Cu(en)₂(H₂O) ₂][Ag₂(pydc)₂(μ-en)]·6H₂O (4) and {[Cd(H₂O)₄Cu(μ-pydc)₂] ·2H₂O}_n (5) have been synthesized and structurally characterized (en = ethylenediamine, dmpen = 1,3-diamino-2,2-dimethylpropane and emim = 2-ethyl-4-methyl-imidazole). Owing to diverse binding modes and conformations of the pydc ligand and the different diamine or imidazole-containing coligands, these complexes exhibit structural and dimensional diversity. Complex 1 exhibits a new unexpected coordination mode of pydc, which is known as a chelating ligand, leading to the formation of a 1D coordination polymer. Complex 2 is the first dinuclear copper(ii)-pydc complex containing a dinuclear metalloligand. Complex 3 is a one dimensional coordination polymer and the Cd(ii) ion is six-coordinated in a distorted octahedral geometry. Complex 4 is the first 3d-4d heterometallic complex and shows two different coordination behaviors of the ethylenediamine ligand: common chelate mode and rare bridging mode. The most striking feature of 4 is the existence of a infinite T5(2) water tape. Complex 5 is the first 3d-4d heteropolynuclear complex obtained from a polynuclear metalloligand. Neighboring metalloligand double-chains bind to Cd(ii) ions to form a two dimensional (2D) layered structure. Complex 4 exhibits weak emission due to the quenching effect of Cu(ii) ions. Complexes 3 and 5 exhibit rare green emission and blue photoluminesence, respectively. Atomically detailed simulations were used to assess the potential of complexes in gas storage and gas separation applications. The antimicrobial properties of the complexes were also investigated by the broth dilution method (MIC). Complexes 4 and 5 are determined to be highly effective for antimicrobial activity.

Full text of DOI:10.1039/c2ce26675j

CrystEngComm
View Article Online
View Journal | View Issue
PAPER
Construction of homo- and heterometallic-pyridine-2,3-
dicarboxylate metallosupramolecular networks with
structural diversity: 1D T5(2) water tape and
unexpected coordination mode of pyridine-2,3-
dicarboxylate3
Cite this: CrystEngComm, 2013, 15,
244
1
ab
a
c
d
e
Fatih Semerci, Okan Zafer Ye ¸s ilel,* Seda Keskin, Cihan Darcan, Murat Ta ¸s
f
and Hakan Dal
Five new homo and heterometallic Cu(II), Cd(II), Cu(II)–Ag(I), Cu(II)–Cd(II) supramolecular networks
with pyridine-2,3-dicarboxylate (pydc), {[Cu(m-pydc)(dmpen)
2
]}
O (4) and {[Cd(H
5) have been synthesized and structurally characterized (en = ethylenediamine, dmpen = 1,3-diamino-2,2-
n
(1), [Cu
2
(m-pydc)
2
(emim)
4
]?2H
2
O
(2),
[
Cd(m-pydc)(emim)
]
2 n
2 2 2 2 2
(3), [Cu(en) (H O) ][Ag (pydc) (m-en)]?6H
2
O)
2 4
Cu(m-pydc)
2
]?2H
2
O}
n
(
dimethylpropane and emim = 2-ethyl-4-methyl-imidazole). Owing to diverse binding modes and
conformations of the pydc ligand and the different diamine or imidazole-containing coligands, these
complexes exhibit structural and dimensional diversity. Complex 1 exhibits a new unexpected coordination
mode of pydc, which is known as a chelating ligand, leading to the formation of a 1D coordination
polymer. Complex 2 is the first dinuclear copper(II)–pydc complex containing a dinuclear metalloligand.
Complex 3 is a one dimensional coordination polymer and the Cd(II) ion is six-coordinated in a distorted
octahedral geometry. Complex 4 is the first 3d–4d heterometallic complex and shows two different
coordination behaviors of the ethylenediamine ligand: common chelate mode and rare bridging mode.
The most striking feature of 4 is the existence of a infinite T5(2) water tape. Complex 5 is the first 3d–4d
heteropolynuclear complex obtained from a polynuclear metalloligand. Neighboring metalloligand
double-chains bind to Cd(II) ions to form a two dimensional (2D) layered structure. Complex 4 exhibits
weak emission due to the quenching effect of Cu(II) ions. Complexes 3 and 5 exhibit rare green emission
and blue photoluminesence, respectively. Atomically detailed simulations were used to assess the potential
of complexes in gas storage and gas separation applications. The antimicrobial properties of the
complexes were also investigated by the broth dilution method (MIC). Complexes 4 and 5 are determined
to be highly effective for antimicrobial activity.
Received 13th October 2012,
Accepted 17th November 2012
DOI: 10.1039/c2ce26675j
www.rsc.org/crystengcomm
Introduction
a
Department of Chemistry, Faculty of Arts Sciences, Eski ¸s ehir Osmangazi University,
Supramolecular assembly of coordination polymers is an
emerging area of research with their intriguing topological
structures and several potential applications in areas such as
catalysis, conductivity, porosity, chirality, luminescence, mag-
2
6480 Eski ¸s ehir, Turkey. E-mail: yesilel@ogu.edu.tr; Fax: +90 222 239357; Tel: +90
22 2393750
2
b
Department of Chemistry, Faculty of Arts and Sciences, K|rklareli University, 39100
K|rklareli, Turkey
c
˙
Department of Chemical and Biological Engineering, Koç University, Istanbul,
1
–8
netism, spin-transition and non-linear optics.
Weak inter-
Turkey
d
molecular forces have been used in intentional strategies for
connecting coordination compounds into a wide variety of
extended networks and these results have shown that
hydrogen bonds acting in concert are capable of marshalling
mononuclear, dinuclear, polynuclear or heteronuclear large
Department of Molecular Biology and Genetic, Faculty of Arts and Sciences, Bilecik
S¸ eyh Edebali University, 11000 Bilecik, Turkey
e
Department of Chemistry, Faculty of Arts and Sciences, Giresun University, Giresun,
Turkey
f
Department of Chemistry, Faculty of Sciences, Anadolu University, Eski ¸s ehir, Turkey
3
Electronic supplementary information (ESI) available. CCDC 887870–887874.
For ESI and crystallographic data in CIF or other electronic format see DOI:
0.1039/c2ce26675j
9
–15
complex ions into desirable motifs.
In the construction of
1
supramolecular networks, water is usually used as a solvent.
1
244 | CrystEngComm, 2013, 15, 1244–1256
This journal is ß The Royal Society of Chemistry 2013

View Article Online
CrystEngComm
Paper
These water clusters which are structurally embedded in
coordination polymer through the hydrogen bonds support
the assembly together with supramolecular networks.
synthesized complexes exhibit structural and dimensional
diversity. In order to understand the potential of these
complexes in gas adsorption and gas separation applications,
atomically detailed simulations were performed. The anti-
microbial properties of the complexes were also investigated
by MIC (minimum inhibitory concentration) analysis to assess
the potential of complexes in medical usage.
1
6–19
At the beginning of this new century, the introduction of
functionality into polymetallic and heterometallic systems has
become one of the aims of a good number of research groups
2
0–22
working in coordination chemistry.
The attraction of
bimetallic coordination polymers is that the simultaneous
presence of two different metals can potentially give rise to
2
3–27
more complex physical properties and structural diversity.
Experimental
Because of the diversity of the coordination modes and high
structural stability, multidentate organic aromatic polycarbox-
ylate ligands have been used to assemble supramolecular
networks organized by coordination bonds and non-covalent
interactions, especially hydrogen bonds. Pyridinedicarboxylic
acids have proved to be interesting versatile ligands and may
exhibit various coordination modes to furnish various struc-
Materials and physical measurements
All chemicals used were of analytical grade and were
purchased commercially. The IR absorption spectra were
recorded in the range of 400–4000 cm
2
1
by means of a
Bruker Tensor 27 FT-IR spectrometer with KBr pellets.
Elemental analyses for C, H and N were carried out at the
2
8,29
¨ ˙
TUBITAK Marmara Research Centre. Magnetic susceptibility
tures with high dimensions.
boxylic acids, the use of bifunctional pyridine-2,3-dicarboxylic
acid (pydcH ) as a bridging ligand to react with transition
In addition to pyridinedicar-
measurements were performed using a Sherwood Scientific
MXI model Gouy magnetic balance at room temperature. The
decomposition enthalpies (DH, J mol ) of each stage were
examined by differential scanning calorimetry (DSC) at a
heating rate of 10 uC min in a Seiko DSC 6200 (Exstar 6000,
Seiko Instruments Inc.). The UV-vis spectra were obtained for
the aqueous solution of the complexes (10
Lambda 35 UV-vis spectrometer in the range 900–190 nm.
2
2
1
metals has been known for its diverse coordination abilities as a
result of the asymmetric coordination environments of the
carboxylate groups at the 2- and 3-positions of the pyridine ring
2
1
2
7–40
that provide variable bridging and coordination modes.
2
2
M) with a
Pyridine-2,3-dicarboxylic acid is remarkably attractive for its
flexible and various coordination modes to construct mono-
nuclear, dinuclear or polynuclear architecture. The deproto-
Crystallographic analyses
22
2
nated pyridinedicarboxylates (pydc and pydcH ) are useful
tools for constructing crystalline architectures because of their
proton donating and accepting capabilities for hydrogen
bonding and their pyridine ring for aromatic interactions.
These ligands are also attractive due to their biological activities
Diffraction measurements were performed at 100 K on a
Bruker Smart Apex CCD diffractometer using Mo Ka radiation
(
l = 0.71073 Å). The structures were solved by direct methods
59
using the program SHELXS-97 with anisotropic thermal
parameters for all non-hydrogen atoms. All non-hydrogen
atoms were refined anisotropically by full-matrix least-squares
methods using SHELXL-97.
obtained by using Mercury.
4
1–45
including neurotoxic and antimicrobial activities.
5
9
The combination of metal ions or clusters and organic
ligands in coordination polymers provides an efficient route to
a new type of photoluminescent material with potential
Molecular drawings were
6
0
Details of the refinement are presented in Table 1; the
crystallographic information files are deposited with the CCDC
(887870–887874).
4
6–52
10
applications.
Complexes consisting of d metals have
been shown to exhibit interesting photoluminescent proper-
5
3–56
ties.
Calculation methods
The driving force behind the comprehensive experimental
and theoretical researches on water clusters lies in under-
In order to assess the potential of synthesized complexes in
gas storage and gas separation applications, molecular
simulations were performed. Grand Canonical Monte Carlo
1
9
standing the unusual properties of bulk water.
Water
clusters are widespread in nature and play a significant role
in the stabilization of supramolecular systems in the solid
6
1
(
GCMC) simulations were used to compute single compo-
1
7
nent adsorption of H and CH in all complexes. Rigid and
2
4
state.
The structural elucidation of water clusters in
solvent-free structures were used in molecular simulations. A
number of studies in the past showed that several general
purpose force fields such as UFF employed in adsorption
simulations of coordination polymers give reasonable agree-
supramolecular system is the key to gain insight into the
5
7
nature of hydrogen bond.
Recent studies showed that coordination polymers exhibit
good potential in gas adsorption and gas separation applica-
tions due to their well-defined pores, high pore volumes, large
62
ment with experiments, therefore we used universal force
63
field (UFF). Spherical Lennard-Jones (LJ) 12–6 potentials
5
8
surface areas and a large variety of chemical functionalities.
64
65
were used to model H2 and CH4 molecules. Interactions
between adsorbates (H and CH ) and adsorbents (complexes)
In this study, five new metallosupramolecular networks
built by 2,3-pyridinedicarboxylic acid were synthesized and
structurally characterized by spectral methods (FT-IR and
photoluminescence), elemental analysis, thermal analysis (TG,
DTG, DTA) and single crystal X-ray diffraction techniques. The
2
4
were modeled using pair-wise interactions between adsorbate
molecules and each atom in the complexes. Mixed-atom
interactions were defined using the Lorenz–Berthelot mixing
rules. The interactions with the atoms of complexes were
This journal is ß The Royal Society of Chemistry 2013
CrystEngComm, 2013, 15, 1244–1256 | 1245

View Article Online
Paper
CrystEngComm
Table 1 Crystallographic data and structural refinement summary for 1–5
1
2
3
4
5
Chemical formula
FW/g mol
Crystal system
Space group
C
17
H
31CuN
5
O
4
C
38
H
50
N
10
O
10Cu
2
C
19
H
23
N
5
O
4
Cd
C
20
H
42Ag
2
8
CuN O
14
14 2 14
C H18CdCuN O
2
1
433.01
Monoclinic
P2 /n
933.97
Monoclinic
P2 /n
497.84
Orthorhombic
P2
933.93
Monoclinic
C2/c
614.26
Monoclinic
I2/a
1
1
1 1 1
2 2
a/Å
b/Å
c/Å
b/u
12.996(5)
22.878(5)
13.696(5)
93.972(5)
4062(2)
8
11.135(5)
13.601(5)
14.886(5)
96.368(5)
2240.5(2)
2
13.536(3)
9.938(4)
16.885(6)
90.000
2271.4(2)
4
23.396(5)
6.654(5)
23.775(5)
112.264(3)
3425.29(3)
4
16.435(5)
7.076(5)
20.060(4)
107.658(5)
2222.94(2)
4
3
V/Å
Z
23
d
c
/g cm
1.416
1.107
1.384
1.013
1.456
0.993
1.811
1.826
1.841
1.984
2
1
m (Mo Ka)/mm
F(000)
1832
972
1008
1892
1228
Data collection
Radiation (Å)
Theta min, max (u)
Dataset
Mo Ka = 0.71069
1.7, 26.5
216 A 15
2.4, 28.4
1.9, 28.4
3.1, 28.6
229 A 31
28 A 8
2.1, 35.4
226 A 21
29 A 8
214 A 14
218 A18
219 A19
218 A 16
212 A 12
217 A 22
2
2
28 A 28
14 A 17
231 A 31
218 A 22
Tot., uniq. data, Rint
35 184, 8419, 0.063 21 186, 5576, 0.062 15 988, 5559, 0.077 14 008, 4224, 0.054 7208, 2776, 0.038
Observed data [I . 2s(I)]
4793
3261
3117
2683
2124
Refinement
Nref, Npar
8419, 487
0.0556, 0.1729
1.02
5576, 286
0.0470, 0.1150
0.98
5559, 266
0.0500, 0.1344
0.82
4224, 221
0.0631, 0.2180
1.11
776, 154
0.0768, 0.2538
1.07
R, wR
2
S
2
3
Min. and max. resd. dens. (e Å
)
20.70, 1.97
20.35, 0.49
20.81, 0.58
22.43, 1.07
21.60, 4.57
6
6
pretabulated on a 0.2 Å grid. The conventional GCMC
technique was used in this work to compute adsorption
matching with 0.5 McFarland turbidity standards. Nutrient
broth containing microorganisms (1 mL) were transferred to
test tubes, to which were added the complexes, and a 2-fold
serial dilution was made. All the test cultures were grown at 37
uC in an incubator. The incubation period was 24 h for
bacterial strains and fungal strains. The minimum inhibitor
concentration, at which no growth was observed, was taken as
6
7
isotherms. The temperature and fugacity of the adsorbing
gases were specified and the number of adsorbed molecules at
equilibrium was calculated. A cut-off distance of 13 Å was used
for LJ interactions. Periodic boundary conditions were applied
in all simulations. The size of the simulation box was set to 2
2
1
6
2 6 2 crystallographic unit cells. Simulations consisted of a
the MIC value (mg mL ).
7
total of 1 6 10 trial configurations, with the last half of the
configurations used for data collection. A configuration is
defined as an attempted translation, or creation, or deletion of
an adsorbate molecule. For the case of mixture simulations,
there is also an attempted swap of the particle species of a
Preparation of the complexes
{[Cu(m-pydc)(dmpen)
]} (1). 10 mL dimethylformamide
2 n
solution of pydcH (1.00 g, 5.98 mmol) was treated with
2
metallic copper (0.38 g, 5.98 mmol) under stirring at 80 uC.
The solution immediately precipitated and was stirred for 1 h
at 80 uC. Then the dmpen ligand (1.22 g, 11.96 mmol) in water
molecule. For mixture simulations, equimolar CH
tures were considered.
4 2
–H mix-
(
10 mL) was added dropwise to this solution. The clear
Antimicrobial activities
solution was stirred for 2 h at 50 uC and then cooled to room
temperature. Dark blue crystals were formed and washed with
10 mL of water and then dried in air. Yield: 33% (based on Cu)
for 1. Anal. found: C, 47.22; H, 7.27; N, 16.14%. Calcd. for:
The antimicrobial activities (MIC values) of complexes were
tested against standard bacterial strains Staphylococcus aureus
ATCC6535, Bacillus cereus ATCC7064, Escherichia coli
ATCC25922, Pseudomonas aeruginosa ATCC27853, one yeast
Candida albicans ATCC10231 and some clinical isolates
methicillin resistant S. aureus, E. coli, Acinetobacter baumannii,
Morganella morganii, Enterobacter aerogenes (isolated by
Faculty of Medicine, Ondokuz May|s University) by using
broth dilution method. The complexes were dissolved in
double distilled water at proper concentration. For the broth
dilution method, cultures were grown in 5 mL nutrient broth
2
1
C
H
31CuN
n(CH), 3273 w, 3215 w, 3130 w; n(NH), 2954 m; 2904 w; 2868 m
as(COO), 1645 sh, 1587 vs; n(CLN), 1458 w; n (COO), 1380 vs;
Dn, 207.
[Cu (m-pydc) (emim) ]?2H O (2). This complex was obtained
O , C: 47.15; H: 7.22; N: 16.17%. IR (cm , KBr):
17
5 4
n
s
2
2
4
2
in a similar way to that of 1, but dmpen was replaced by emim
ligand (1.32 g, 11.96 mmol). Green crystals were formed and
washed with 10 mL of water and then dried in air. Yield: 48%
(based on Cu) for 2. Anal. found: C, 48.87; H, 5.42; N, 15.04%.
Calcd. for: C H N O Cu , C: 48.85; H: 5.42; N: 15.00%. IR
(Merck) at 37 uC for 18 h in shaking at 175 rpm. Bacterial and
yeast cells were suspended in 50 mL nutrient broth at a
concentration of approximately 5 6 10 cells per mL by
3
8
50 10 10
2
5
21
2
(cm , KBr): n(H O), 3491 w; n(NH), 3158 s; n(CH), 3069 w,
1
246 | CrystEngComm, 2013, 15, 1244–1256
This journal is ß The Royal Society of Chemistry 2013

View Article Online
CrystEngComm
Paper
2
1
974 w, 2750 w, 2634 w; nas(COO), 1671 vs, 1586 vs; n(CLN),
478 m; n (COO), 1393 vs, 1365 vs; Dn, 278 and 221.
Cd(m-pydc)(emim)2]n (3). This complex was obtained in a
similar way to that of 2, but metallic copper was replaced by
Cd(CH COOH) ?2H O (1.59 g, 5.98 mmol). Colorless crystals
[Cu(m-pydc)(dmpen) ] (1). [Cu(m-pydc)(dmpen) ] (1) crystal-
lizes in monoclinic P2 /n space group. The asymmetric unit of
1
the complex contains two independent [Cu(m-pydc)(dmpen) ]
2
unit (Fig. 1a). The nitrogen atom of pydc ligand was not
coordinated to the Cu(II) center in 1 (Scheme 1) and this
situation is seen in the literature for the first time. The
unexpected non-coordination of the pyridine nitrogen atom in
1 may arise from the steric effect of the methyl groups within
the 1,3-diamino-2,2-dimethylpropane ligand that occupy a
certain amount of space around the pyridine nitrogen atom
2
n
2 n
s
[
3
2
2
were formed and washed with 10 mL of water and then dried
in air. Yield: 54% (based on Cd) for 3. Anal. found: C, 45.78; H,
23 5 4
4.71; N, 14.12%. Calcd. for: C19H N O Cd, C: 45.84; H: 4.66;
2
1
N: 14.07%. IR (cm , KBr): n(NH), 3142 s; n(CH), 3087 w, 2752
w, 2625 w, 2625 w; nas(COO), 1623 vs, 1576 vs; n(CLN), 1466 vs;
ns(COO), 1404 vs, 1378 vs; Dn, 219 and 198.
3
2 n
(Fig. S1, ESI ). In [Cu(m-pydc)(dmpen) ] (1), the nitrogen
[
Cu(en) (H O) ][Ag (pydc) (m-en)]?6H O (4). The complex
atoms of dmpen ligands coordinated to the copper(II) ions to
form equatorial planes around the metal centers and one of
the carboxylate groups of pydc ligands bonded to the Cu(II)
ions by their O1 and O5 carboxylate oxygen atoms in the axial
positions. The mononuclear units at ¡1/2 + x, 1/2 2 y, ¡1/2 +
z completed the coordination around the Cu(II) center using by
their O3 and O8 carboxylate oxygen atoms of pydc ligand and
2
2
2
2
2
2
was synthesized in three stages. First 10 mL DMF solution of
pydcH2 (1.00 g, 5.98 mmol) was treated with KOH (0.67 g,
1.96 mmol) and metallic copper (0.38 g, 5.98 mmol) under
stirring at 80 uC. The resulting solution was left to evaporate
slowly in the dark at room temperature for several weeks. The
dark blue crystals of K
washed with 10 mL of water and then dried in air. In the
second stage a solution of K [Cu(pydc) ]?3H O (0.50 g, 0.956
1
2 2 2
[Cu(pydc) ]?3H O were formed and
2
2
2
mmol) in water (20 mL) was added dropwise with stirring to a
solution of AgNO (0.32 g, 1.91 mmol) in water (20 mL). The
3
solution immediately precipitated and was stirred for 1 h at 80
uC. The precipitation of Ag [Cu(pydc) ]?H O product was
2
2
2
filtrated off and dried in air. In the last stage uncharacterized
light blue Ag [Cu(pydc) ]?H O was added to 10 mL water and
the mixture was stirred for 4 h at 50 uC and then en (0.074 g,
.2 mmol) in water (25 ml) was added to the mixture to give a
2
2
2
1
clear solution. The resulting solution was left to evaporate
slowly in the dark at room temperature for several weeks until
violet crystals were formed, which were washed with 10 mL of
water and then dried in air. Yield: 67% (based on Cu) for 4.
Anal. found: C, 26.69; H, 4.77; N, 12.41%. Calcd. for:
2
1
C
20
H
42Ag
2
CuN
O), 3358 m; n(CH), 3294 s, 3238 s; n(NH), 2975 m;
953 m; 2886 m; nas(COO), 1593 sh, 1571 vs; n(CLN), 1454 w;
ns(COO), 1382 vs; Dn, 211.
[Cd(H O) Cu(m-pydc) ]?2H O} (5). This complex was
8
O
14, C: 26.75; H: 4.71; N: 12.48%. IR (cm
,
KBr): n(H
2
2
{
2
4
2
2
n
obtained in a similar method to that of 4, but AgNO
3
was
replaced by Cd(CH COOH) ?2H O (1.59 g, 5.98 mmol). Sky-
3
2
2
blue crystals were formed and washed with 10 mL of water and
then dried in air. Yield: 21% (based on Cd) for 5. Anal. found:
C, 27.37; H, 2.95; N, 4.56%. Calcd. for: C H CdCuN O , C,
1
4
18
2 14
2
1
2
7.31; H, 2.89; N, 4.49%. IR (cm , KBr): n(H
2
O), 3456 m;
n(CH), 3201 w, 3156 w; n (COO), 1644 vs, 1588 vs; n(CLN), 1454
as
s
m; n (COO), 1395 m, 1367 m; Dn, 249, 221.
Result and discussion
Crystal structures
The relevant crystal data and experimental conditions with the
final parameters are summarized in Table 1. The selected
bond lengths and angles together with the hydrogen bonding
geometry are tabulated in the relevant sections. The molecular
structures of the compounds with atom numbering scheme
are shown in the relevant sections .
Fig. 1 (a) View of the asymmetric unit of 1 containing two different chains with
…
…
atom-labelling scheme and (b) supramolecular N–H O and C–H p interactions
between two chains in 1.
This journal is ß The Royal Society of Chemistry 2013
CrystEngComm, 2013, 15, 1244–1256 | 1247

View Article Online
Paper
CrystEngComm
interaction using its hydrogen atom with the aromatic ring
center of pydc ligand at (ii) 21/2 + x, 1/2 2 y, 21/2 + z to bond
the two polymer to each other. In 1, the N2, N3 and N4 atoms
act as hydrogen bond donors via one of their hydrogen atoms
i
i
with the N1 , O2, and O4 , respectively, to form intrachain
hydrogen bonds (Fig. 1b and Table S6, ESI ). In addition to
3
these interchain hydrogen bonds, the N5 atom of the dmpen
ligand in 1 acts as a hydrogen bond donor via its hydrogen
ii
ii
atoms to O6 and O8 atoms of pydc ligand. In chain 2, the N7,
N8 and N9 atoms act as hydrogen bond donors via their one of
iii
ii
hydrogen atoms with the O7 , O6, and N10 , respectively, to
form intrachain hydrogen bonds. The remaining hydrogen
atoms of these donors composed inter-polymer hydrogen
iv
i
bonds to bond polymers to each other with O4 and O2 atoms
and the N6 atom of the dmpen ligand in chain 1 acting as a
i
i
hydrogen bond donor via its hydrogen atoms to O2 and O3
atoms of pydc ligand (Fig. 1b, Table S6, ESI ). All of the
3
interchain hydrogen bonds link the chains to each other to
form three dimensional network.
[
Cu
2
(m-pydc) (m-pydc)
2
(emim)
4
]?2H
2
O (2). The complex [Cu
2
2
(emim)
4
]?2H O (2) crystallizes in the monoclinic P2 /n space
2
1
group. The asymmetric unit of the complex contains a Cu(II)
ion which lies on an inversion center, a pyridine-2,3-
dicarboxylate dianion (pydc), two neutral 2-ethyl-5-methylimi-
dazole (emim) ligands and a hydrate water (Fig. 2a). The
crystal structure of 2 showed the 2-ethyl-4-methylimidazole
ligands changed to 2-ethyl-5-methylimidazole ligands by
proton transfer on the nitrogen atoms of the imidazole rings
during the complexation reaction. We reported similar proton
transfer reactions in imidazole rings in our previous stu-
Scheme 1 Coordination modes for the pydc ligand in 1–5.
arrange in order to form a 1D polynuclear structure by the two-
fold screw axis, so the mononuclear units go at x + n, y, z + n
and ¡1/2 + x + n, 1/2 2 y, ¡1/2 + z + n symmetries (n is an
integer) to compose two infinite different one dimensional
chains along the [100] and [001] directions (Fig. 1b) and the
pydc ligands act as bridge between the symmetry related
6
8,69
dies.
2 3
The two [CuO N ] coordination systems in the
dinuclear structure are formed by two oxygen and one nitrogen
i
atoms from two pydc ligands [Cu1–O1 = 1.986 (2), Cu1–O3 =
2.191 (2) and Cu1–N1 = 2.017 (2) Å, (i) 2x, 2y, 2z + 1] and two
N atoms from two emim ligands [Cu1–N2 = 1.987 (2) and Cu1–
[
Cu(dmpen) ] complex units.
N4 = 1.979 (2) Å] in the asymmetric unit (Table S2, ESI ). The
2
3
dinuclear structure is completed with the asymmetric unit at
2x, 2y, 2z + 1 via bonding the remaining carboxylate oxygen
The coordination bond lengths in the polymers, for Cu1–O1,
i
ii
Cu1–O3 , Cu2–O5 and Cu2–O8 are found to be 2.388, 2.638,
.348 and 2.597 Å, respectively ((i) 1/2 + x, 1/2 2 y, 1/2 + z and
ii) 21/2 + x, 1/2 2 y, 21/2 + z) and Cu–Ndmpen bond lengths
were in the range of 2.007(4) to 2.032(3) Å (Table S1, ESI ). The
i
2
(
(O3 and O3 ) to the Cu(II) ion to form the first identified
dinuclear structure for Cu(II) complexes of pydc ligand. So the
two pydc anions act as a bridge between two [Cu(emim)2]
complex units (Fig. 2b). A similar dinuclear complex was
3
shortest Cu–Cu separation was found to be 6.114 Å between
the polynuclear chains. In 1, the pyridine rings of pydc are
nearly planar with the largest deviation from the plane being
that of atom C6 [0.006(5) Å] in chain 1 and C20 in chain 2
7
0
reported only for a cobalt complex of pydc. The bond length
of the Cu–O bonds (1.984 and 2.191 Å) and Cu–Npydc (2.016 Å)
are comparable to those of other some pydc complexes (Cu–O
[
0.008(5) Å] and the two pyridine ring planes in the asymmetric
= 1.986 (2)–2.191 (2) and Cu–N
pydc
= 1.980 (2)–2.017 (2) Å) in
3
2,71–75
unit are nearly parallel to each other, with the angle between
the two planes being 2.055(8)u. The angle between the
symmetry related (i and ii) pyridine rings of pydc ligands
was 18.592(8)u in chain 1 and 14.669(9)u in chain 2. The
carboxylate groups were not in the pyridine ring planes. The
angle between the pyridine ring planes and carboxylate groups
were 41.86 and 67.35u for (O1–C2–O2) and (O3–C7–O4),
respectively, in chain 1, and 41.29 and 66.53u for (O5–C18–
O6) and (O7–C24–O8), respectively, in chain 2. The nearest
distance between the aromatic rings of pydc ligands in
polymer chains is found to be 5.235(3) Å at ¡3/2 + x, 1/2 2
y, ¡1/2 + z and 7.765 Å in the asymmetric unit. The C15 atom
the literature.
The bond lengths were compared with
the dinuclear cobalt complex and some polynuclear copper
complexes which contain acceptably similarly orientated pydc
ligands. In complex 2, the pyridine rings of pydc are nearly
planar with the largest deviation from the plane being that of
atom C3 [0.005(3) Å] and the two pyridine ring planes are
parallel to each other, with the distance and angle between the
two planes being 4.097(2) Å and 0u, respectively. One of the
carboxylate groups (O1–C2–O2) was nearly in the pyridine ring
plane with an angle of 4.85u and the other carboxylate group
(O3–C4–O4) was nearly perpendicular to the pyridine ring
plane with an angle of 86.74u. The bond lengths and angles of
O1–C1–O2 reflect the p electron delocalization through these
…
of dmpen ligand in the asymmetric unit showed the C–H p
1
248 | CrystEngComm, 2013, 15, 1244–1256
This journal is ß The Royal Society of Chemistry 2013

View Article Online
CrystEngComm
Paper
7
6
…
et al. The literature survey shows that the X–H M angle is
around 110–170u for anagostic interactions, which reflects
largely electrostatic interactions and around 90–140u for
agostic interactions suitable with 3-center–2-elecron interac-
7
7
tions. The bond lengths and angles indicated that anagostic
interactions are present in 2. The anagostic interactions were
first explored for pydc or emim complexes in this work. The
C19–H19 of an emim ligand formed intramolecular hydrogen
i
bonds with the O3 atom of pydc ligand at ((i) 2x, 2y, 2z + 1).
The dinuclear complex units bonded to each other along the c
…
…
i
…
iii
axis by the O5–H5w O1, C2–H2 O5 and O5–H5w9 O4
intermolecular hydrogen bonds, so the hydrated water
molecules act as a bridge between the dinuclear complexes
(Table S7, ESI
3
). The complex unit lying at the 2x (+1/2 and
2
1/2), y + 1/2 + n, 2z + 1/2 and x (+1/2 and 21/2), 2y + 1/2 + n,
z + 1/2 symmetries (n is an integer) that formed a dinuclear
complex bonded the dinuclear complex units to each other
…
ii
…
iii
along the x and y axis with the N3–H3 O4 , and N5–H5 O2
intermolecular hydrogen bonds (Fig. S2, Table S7, ESI ). So
3
these intermolecular hydrogen bonds formed three dimen-
sional network.
[
Cd(m-pydc)(emim)
shows that 3 crystallizes in the orthorhombic space group
P2 and has an infinite 1D chain structure. As shown in
2 n
] (3). The X-ray crystallographic analysis
1 1 1
2 2
Fig. 3a, a crystallographically independent Cd(II) ion is
surrounded by a distorted octahedral geometry with two emim
ligands and three oxygen and one nitrogen atoms from two
3
pydc ligands (Table S3, ESI ). The equatorial plane of the
octahedral geometry is provided by one nitrogen atom from
emim, one nitrogen atom from pydc ligand and two oxygen
atom from different two pydc ligands. The axial position is
occupied by a carboxylate oxygen atom from pydc and a
nitrogen atom from the emim ligand. The pydc ligand is
coordinated to two Cd(II) ions in a bis(bidentate) mode with its
one nitrogen atom of the pyridine ring and three oxygen atoms
of the carboxylate groups to form a one-dimensional chain.
…
The crystal packing of the complex is a composite of C–H p
and hydrogen bonding interactions (Table S8, ESI
Fig. 2 (a) View of the asymmetric unit of 2 with atom-labelling scheme and (b)
hydrogen bonding interactions between two dinuclear units in 2 (symmetry
code: (i) 1 2 x, 1 2 y, 2 2 (z).
3
). The
adjacent 1D chains extend into a 3D supramolecular network
…
…
…
by N5–H5 O4 and N9–H9 O3 hydrogen bonds and C–H p
interactions (Fig. 3b and Fig. S3a, ESI
…
3
). Furthermore, there is
an interchain C–H p interaction between C–H groups (C13–
three atoms. The distance and angles between the five
membered ring plane formed by coordination and symmetry
related pyridine ring planes of pydc were measured as
H13b, C16–H16a and C16–H16c) and imidazole (Cg1: N4–C14–
…
…
i
C15–N5–C17; H13b Cg1 = 3.039, H16c Cg1 = 3.218 Å, (i)
2x, 21/2 + y, 1.5 2 z) or pyridine (Cg2: N1–C1–C2–C3–C4–C5,
2
3
.492(11) Å and 6.00(12)u, respectively. There were also C–
…
i
…
H16A Cg2 = 2.921 Å) (Fig. S3b, ESI
3
).
O p interactions between the uncoordinated carboxyl oxygen
O2) and aromatic rings of pydc [3.535(3) Å] (Fig. 2b). Similar
[
Cu(en) (H O) ][Ag (pydc) (m-en)]?6H O (4). Complex 4 crys-
2
2
2
2
2
2
(
…
tallizes in the monoclinic C2/c space group. The asymmetric
unit of the complex contains a Cu(II) ion, an ethylenediamine
C–O p interactions were reported as 3.163 and 3.239 Å
3
2,71
previously in two polynuclear copper(II) complexes of pydc.
(
en) ligand and an aqua ligand which lie on a crystallographic
The most striking property of complex 2 is the presence of
the rare C–H Cu type hydrogen bonding interactions. The
…
centre of symmetry (2x, y, 3/2 2 z), a silver(I) ion, a pyridine-2,3-
dicarboxylate dianion (pydc) and a half en ligands and three
hydrate waters lying on a crystallographic centre of symmetry
(1/2 2 x, 1/2y, 1 2 z) (Fig. 4). The compound contains two
complex units which are diaquabisethylenediamincopper(II),
distance of C9–H9A and C15–H15A atoms of the ethyl group of
emim ligands and Cu(II) centers are 2.920(5) and 2.969(5) Å,
…
respectively. The angles are 116.37(5)u for C9–H9A Cu and
…
1
12.52(5)u for C15–H15A Cu. These results indicated an
interaction between the C–H and Cu(II) center (Table S7,
…
[Cu(H
2
O)
2
(en)
2
]
and m-ethylenediamine bis(pyridine-2,3-
ESI
3
). This X–H M type interaction, named as agostic or
dicarboxylatosilver(I)), [Ag(pydc)
(m-en)], and six hydrate water
2
anagostic interactions, was first suggested in 1972 by Roe
molecules.
This journal is ß The Royal Society of Chemistry 2013
CrystEngComm, 2013, 15, 1244–1256 | 1249

View Article Online
Paper
CrystEngComm
ligands were oriented by a symmetry operation in cis- and
trans-forms, respectively. To form the Ag(I)–pydc parts of the
compound, the pydc ligands bonded to Ag(I) ions via their
pyridine nitrogen and an oxygen atom of the carboxylate
groups, which is in the ortho position. The en ligand acted in a
bridging manner between the two Ag(I)–pydc parts to form an
en bridged dinuclear [Ag (pydc) (m-en)]. The bond lengths
2
2
were measured as 2.451(5), 2.178(5) and 2.158(5) Å for O1–Ag1,
N1–Ag1 and N2–Ag1, respectively.
The pyridine rings of pydc are nearly planar with the largest
deviation from the plane being that of atom C6 [0.007(6) Å ].
The two pyridine ring planes in the dinuclear structure are
parallel to each other and the distance and angles between the
two planes are 1.189 Å and 0u, respectively. One of the
carboxylate groups (O1–C2–O2) was nearly in the pyridine ring
plane with the angle of 3.26u and the other carboxylate group
(O3–C7–O4) was nearly perpendicular to the pyridine ring
planes with an angle of 85.39u.
The complex units in the compound showed interesting
arrangements. [Ag(pydc) (m-en)] complex units related by
2
symmetry were bonded to each other by Ag–Cg secondary
interactions (3.445 and 3.377 Å; Cg refers to the center of
…
…
gravity of the pydc rings) and C–H O and N–H O hydrogen
bonds to form [Ag(pydc) (m-en)] complex layers through the b
axis (Fig. S4b, ESI ).
The independent [Cu(H O) (en) ]
2
3
2
+
complex ion units
2
2
2
settled between the layers by symmetry and bonded the layers
to each other by using their aqua ligands and the NH parts of
2
…
…
en ligands to form N–H O and O–H O hydrogen bonds with
the uncoordinated carboxylate oxygens of pydc ligands of
Fig. 3 (a) View of the asymmetric unit of 3 with atom-labelling scheme and (b)
…
hydrogen bonding and interchain C–H p interactions in 3 (symmetry codes: (i)
[Ag(pydc)
independent [Cu(H
dinuclear [Ag(pydc)
(m-en)] complex units (Fig. S5, ESI
3
). So, the
complex units bridged the
(m-en)] complex units that form layers
2
2
+
2
1/2 + x, 1.5 2 y, 1 2 z, (ii) 1/2 + x, 1.5 2 y, 1 2 z).
2
2 2
O) (en) ]
2
along the a, b and c axis by symmetry to form three
dimensional supramolecular networks which have solvent
accessible voids along the b axis (Fig. 5). Interestingly, in these
voids, the crystal water molecules are bonded to each other by
hydrogen bonds to form the pentagonal water rings. In the
infinite water tape involving cyclic pentamer water clusters
extended along the c-axis with a T(5)2 motif, which has been
One of the most striking features of 4 is that it has two en
ligands in different coordination manners. One of them acts
as a bidentate ligand and is coordinated to the Cu(II) ion and
the other one acts as bridged ligand between the two Ag(I)–
pydc units. The two en ligands in different manners were seen
3
in this work for the first time (Fig. S4a, ESI ). The two en
7
8
reported rarely so far
3
(Fig. S6a, ESI ). The geometric
ligands occupied the equatorial positions of octahedral
around the Cu(II) center and aqua ligands coordinated to
Cu(II) through the axial positions to complete an octahedral
geometry (Cu1–O8 = 2.614(5), Cu1–N3 = 2.004(6) and Cu1–N4 =
2.012(7) Å) (Table S4, ESI
3
). The ethylenediamine and aqua
…
Fig. 4 Perspective view of supramolecular interactions (Ag p, hydrogen bond
…
and O–H Ag) of the 4 with atom-labelling scheme (symmetry code: (i) 1/2 2 x,
Fig. 5 Three dimensional supramolecular network of 4 which have 1D T5(2)
water tape inside the voids along the b axis.
1
/2 2 y, 1 2 z).
1
250 | CrystEngComm, 2013, 15, 1244–1256
This journal is ß The Royal Society of Chemistry 2013

View Article Online
CrystEngComm
Paper
parameters of the 1D water cluster are summarized in Table
…
3
S8, ESI. The average O O distance in the water tape is
ligands act as bidentate ligands using their pyridine N and a
carboxylate O in the ortho position and act in a bridging
manner using one of their carboxylate O in the meta position
to form a monometallic 1D polynuclear structure. Only one of
the two carboxylate oxygens was used to coordinate and to
form a polynuclear arrangement. This work is the first
example of polynuclear pydc compounds having different
metals (3d–4d) that are in different coordination spheres or
three carboxylate oxygen atoms used to form a 2D polynuclear
arrangement (Fig. 6b).
2
.832 Å, which is slightly shorter than that observed in liquid
water (2.854 Å) and similar to those in the ice II phase (2.77–
.84 Å). The water rings also act as hydrogen bond donors to
carboxylate oxygens of pydc ligands of [Ag(pydc) (m-en)]
complex units (Fig. S6b, ESI ). The bridged en ligands act as
hydrogen bond donors to the T(5)2 water cluster by using one
hydrogen atom of each of their two NH parts and so each of
2
2
3
2
the dinuclear [Ag(pydc) (m-en)] complex units act as a bridge
2
In 5, pydc ligands bonded to Cu(II) ion using their pyridine
N and carboxylate O in the ortho position to compose the
equatorial plane of octahedron around the copper ion, similar
to the literature examples. The other carboxylate oxygens (O3
and O4) in the meta position were free to bond in a bridging
manner. Meanwhile, one of the carboxylate oxygens (O3) in the
meta position coordinated to a symmetry related Cu(II)
through the axial position to form a 1D [Cu(pydc)] polynuclear
complex along the c axis, like the literature examples, as in
different literature examples the other carboxylate oxygens
between the six infinite water chains lying along the b axis.
More interestingly, besides the classical hydrogen bonds, an
…
intermolecular O–H Ag close interaction between H5A in
crystal water molecules and Ag1 centers have been observed.
…
…
…
The Ag1 H5A, Ag1 O5 distances and Ag1 O–H5A angle are
2
.962, 3.687 Å and 139.82u, respectively and this intermole-
…
cular O–H Ag close interaction is well described as being
weak intermolecular O–H Ag hydrogen bonding.
Crystal structure of {[Cd(H O) Cu(m-pydc) ]?2H O} (5).
2 n
…
79
2
4
2
Complex 5 crystallizes in the monoclinic I2/a space group.
The asymmetric unit of the complex contains a Cu(II) ion, a
Cd(II) ion, a pyridine-2,3-dicarboxylate dianion (pydc), two
aqua ligands and a crystal water molecule (Fig. 6a). In the
literature there are some polynuclear Cu(II) complexes of pydc
ligands formed with only pydc ligands. In this report the pydc
(O4) in the meta position bonded to Cd(II) coordinated by four
aqua ligands to form polymeric structure along the b axis. So,
the Cd(II) ions act as a bridge bonding 1D chains to each other
by bonding to the O4 atom of pydc ligands in Cu(II)–pydc
polymers to form a two dimensional network.
The Cu atoms displaying distorted octahedral geometry were
bonded to two pyridine N atoms (Cu1–N1 = 2.134 Å) and two
O4 atoms of the carboxylate groups in the pyridine ortho
positions (Cu1–O1 = 1.700 Å) which form the equatorial plane
3
(Table S5, ESI ). The pydc ligands also bonded to Cd(II) ion by
the O4 atoms of the carboxylate groups in the pyridine meta
positions (Cd1–O4 = 1.946(4) Å) to form the complex polymer
chain. The distorted octahedral geometry around the
cadmium(II) centers was completed by the symmetry related
aqua ligands (Cd1–O6 = 2.291 and Cd1–O7 = 2.797 Å). The O3
atoms of the carboxylate group in the pyridine meta positions
i
bonded to the Cu1 atom of adjacent polymer (Cu1–O3 = 2.734,
(i) x, 21 + y, z). The distorted octahedral geometry around the
Cu(II) atom in the asymmetric unit was completed by the O3
atoms of adjacent polymers at x, 1 + y, z and 1 2 x, 1 2 y, 1 2 z.
The pyridine rings of pydc were nearly planar with the
largest deviation from the plane being that of atom C2
[0.031(8) Å] and the two pyridine ring planes in the polymer
were parallel to each other (0u) and the distance between the
nearest two centers of phenyl rings was measured as 5.449(5)
Å. The one of carboxylate group (O1–C7–O2) was nearly in the
pyridine ring planes with an angle of 4.54u and the other
carboxylate group (O3–C1–O4) was nearly perpendicular to the
pyridine ring planes with an angle of 81.56u. We also found C–
…
O p interactions between the pydc ring and uncoordinated
carboxylate oxygens with lengths of 3.711(8) Å.
All of the aqua ligands coordinating to Cd(II) ion and crystal
water lying between the Cu(II)–pydc polymer chains act as
hydrogen bond donors via one of their hydrogen atoms to the
carboxylate oxygens of pydc ligands. Using the other hydrogen
atom (H6A) the O6 of aqua ligands also formed hydrogen
bonds with the O5 atom of crystal water at x, 21 + y, z (Table
Fig. 6 (a) View of the asymmetric unit of 5 with atom-labelling scheme (b) 2D
sheet structure containing hydrogen bonding interactions in 5 (symmetry code:
3
S9, ESI ). The O5 atoms of crystal waters also formed hydrogen
(
i) x, 21 + y, z).
bonds with the O4 atom of aqua ligands and so act as
This journal is ß The Royal Society of Chemistry 2013
CrystEngComm, 2013, 15, 1244–1256 | 1251

View Article Online
Paper
CrystEngComm
bifurcated hydrogen bond donors. So the crystal waters and
aqua ligands coordinating to Cd(II) ions formed metallo–water
clusters lying parallel to the b axis.
kinetic diameter than H
pores of two structures, 4 and 5. Fig. 8 shows single
component and equimolar binary mixture adsorption iso-
2
, CH
4
can only be adsorbed into the
4 2
therms of CH and H in these complexes. As should be
Computational results
expected from the single component isotherms, adsorption
favors CH4 over H2 in the mixture since the more strongly
adsorbing CH molecules exclude H molecules in the pores. It
We examined gas adsorption properties of complexes to
understand their potential in storage applications. Fig. 7
4
2
represents the single component adsorption isotherms of H
in all complexes at 77 and 298 K. The scatters are the results
from GCMC simulations whereas the lines are the single
component adsorption isotherm fits. At 298 K, H is below
2
saturation in all complexes and gas uptake increases as the
2
is obvious from Fig. 8 that the amount of adsorbed gas in the
mixture is smaller than the amount of adsorbed gas in the
single component case due to the competitive adsorption
between two gas species. In addition to mixture GCMC
simulations, we also predicted mixture adsorption isotherms
using a theoretical approach. Ideal Adsorbed Solution Theory
(IAST) is a well-developed technique to describe adsorption
equilibria for components in a gaseous mixture, using only
data for the pure component adsorption equilibria at the same
pressure increases. At 77 K, except complex 1, all complexes
8
0
are saturated with H
2
. Fig. 7 shows that complexes 2–5 can be
potential candidates for H2 storage. Since CH4 has a larger
Fig. 7 Adsorption isotherms for H
2
at 77 K (a) and 298 K (b).
4 2
Fig. 8 Adsorption of CH and H in complexes 4 (a) and 5 (b) at 298 K.
1
252 | CrystEngComm, 2013, 15, 1244–1256
This journal is ß The Royal Society of Chemistry 2013

View Article Online
CrystEngComm
Paper
temperature and on the same adsorbent. This theory is known
to give accurate results in many nanoporous materials except
in materials characterized by strong energetic or geometric
heterogeneity. Practical application of IAST requires that the
functional form of the single component isotherms must be
specified. In order to apply IAST, single component adsorption
(4), which contain a Ag molecule, has a higher activity
(47 mg mL in all studied microorganisms) than the other
new complexes.
2
1
8
1
The antimicrobial activities of some pyridine-2,3-dicar-
boxylic acid complexes have been reported previously in the
8
2,83
literature.
In recent years, metal complexes are very
isotherms of CH
4
and H
2
were fitted using a dual site
interesting materials for antimicrobial agents. Biocations such
as Co, Ni, Cu, Fe, and metal ions such as Cd, Ag were found to
have very high activity in inhibition of bacterial growth.
Langmuir isotherm and these fits were shown as continuous
lines in Fig. 8. The predictions of IAST were found to be in a
good agreement with the mixture GCMC simulations. This
result indicates that IAST can be used to predict mixture
adsorption accurately in the synthesized materials. A good
indication of the ability for separation is the adsorption-based
selectivity of a porous material for different components in the
8
4
Complex 4 which contains Ag(I) ions has very high activity. It is
known from previous studies that many complexes containing
8
4–87
Ag(I) are highly effective antimicrobial agents.
We think
that these complexes can be used in treatment of some
diseases and disinfection.
mixtures. The adsorption-based selectivity for CH
4
relative to
Spectroscopic and magnetic properties
H is defined as S
~ðxCH =xH Þ=ðyCH =yH Þ, where x and y
2
CH4=H2
4
2
4
2
Compounds were investigated by FT-IR spectroscopy. Broad
bands observed in the range from 3565–3365 cm are attributed
to the asymmetric and symmetric stretching modes of water
are the molar fractions of the adsorbed and bulk phase,
respectively. The CH adsorption selectivities of complexes 4 and
were found to be 12 and 17, respectively, at 10 bar and 298 K.
This result suggests that these materials are potential candidates
for CH –H separation applications.
Complexes 4 and 5 are found to adsorb more H
21
4
5
2
1
molecules in 2, 4 and 5. The weak peaks at 2941 and 2685 cm
are characteristic of aliphatic C–H stretching bands of the CH
CH /CH groups. This confirms the existence of the dmpen, emim
3
/
4
2
2
2
compared
and en ligands in complexes 1–4. The absence of strong
to the complexes 1–3. This can be explained by the following
discussion: complex 5 is a 2D coordination polymer and it
extends to 3D due to London interactions. The 2D interlayer
space in the 3D supramolecular structure can be responsible
21
absorption bands around 1720 cm indicates the full deproto-
nation of carboxylate groups of the pydc ligands, as revealed by
the X-ray single-crystal structure analysis. The very strong peaks
range from 1671–1571 and 1404–1365 cm correspond to nasym
and nsym of the carboxylate group, respectively.
The electronic spectra of water solutions of the complexes 1,
21
2
for the high amount of H adsorption in complex 5. In
complex 4, a 1D structure is formed due to the connection of
2
2
…
2 2
Ag (pydc) (m-en)] anionic units with dihapto Ag C interac-
[
2
, 4 and 5 display broad absorption bands at 604 (e = 91 L
…
i
…
i
tions [Ag1 C4 = 3.279(6) and Ag1 C5 = 3.318(6) Å, (i) 2x, 1 2
21
21
21
21
21
mol cm ), 646 (e = 45 L mol cm ), 563 (e = 62 L mol
…
y, 1 2 z]. Complex 4 extends to 2D due to the Ag p
21
21
21
cm ) and 633 nm (e = 50 L mol cm ) respectively, which
are assigned to the E A T2g the transition for 1, 4, 5 and dxz
dyz A dx22y2 (a A b ) transition for 2. The strong absorption
…
ii
interactions of adjacent 1D units [Ag1 Cg1 = 3.377 Å, Cg1 =
g
,
N1, C2, C3, C4, C5, C6, (ii) 2x, 2y, 1 2 z]. The 2D units form
strong hydrogen bonds with the cationic [Cu(en) (H O) ]
2 2 2
units that results in a 3D supramolecular structure with 1D
pores. When the T5(2) water tapes are removed from the 1D
1
1
2
+
bands below 300 nm are due to n A p* and p A p* transitions
of en, dmpen, emim and pydc ligands.
Photoluminescent properties of 3–5 and pydcH
2
were
pores, these pores become available for guest H adsorption.
2
investigated in the crushed single-crystal sample at room
temperature. Complexes 3 exhibit intense blue fluorescent
emission bands at 406 nm and a shoulder at 483 nm upon
excitation at ca. 347 nm. These emissions can probably be
assigned to the intraligand (p* A p) fluorescent emission
because similar emissions are observed at 420 nm and a
shoulder at 483 nm for the free pydc. The enhancement of the
emissions for 3 may be attributed to the chelation of the
ligand to the metal center and ligand enhances conforma-
tional rigidity due to their coordination to Cd(II) ions resulting
in a decrease in the nonradiative decay of intraligand excited
states. Excitation at 335 nm leads to a weak fluorescent
emission band with two maxima at about 488 and 537 nm in
complex 4. The first emission peak at 488 nm can probably be
assigned to the ligand centered fluorescent emission because
similar emissions under the same conditions are observed for
the free pydc at 483 nm. Furthermore, the added peak at 537
nm may be attributed to the ligand-to-metal charge transfer
(LMCT) bands. The chelation of the ligand to the silver center
plays an important role in red shift of the emission. Excitation
of the complex 5 at 402 nm produces weak green emission
with two maxima at 557 and 598 nm, as shown in Fig. 9. The
2
The lower H adsorption of complexes 1–3 was attributed to
lower pore volume of the materials.
Antimicrobial activity
We performed experiments for microbial activity to under-
stand the potential of complex in biomedical applications. The
antimicrobial activity results of the synthesized complexes are
21
3
presented in Table S10, ESI, as MIC values (mg mL ), which is
the minimum concentration to inhibit the growth of bacteria or
yeast. According to results, the MIC values of the complexes
indicate that while the activity of [Cu(en) (H O) ][Ag (pydc)
2
2
2
2
2
21
(
2
m-en)]?6H O (4) was at 47 mg mL at all studied microorgan-
isms, the antimicrobial activity of {[Cd(H O) Cu(m-pydc) ]?2H O}
n
5) was in the range of 23–187 mg mL in the studied micro-
2
4
2
2
2
1
(
organisms. The MIC values of [Cu(m-pydc)(dmpen) ] (1) and
2
n
[
2 2 4 2
Cu (m-pydc) (emim) ]?2H O (2) were 2250–4500 and 1300 mg
21
mL , respectively. As a result, the complexes did not show any
difference between the cell wall of bacteria. The complexes did
not show any difference in activity according to prokaryote or
eukaryote. These complexes have a large effect spectrum on
2 2 2 2 2 2
bacteria. The complex [Cu(en) (H O) ][Ag (pydc) (m-en)]?6H O]
This journal is ß The Royal Society of Chemistry 2013
CrystEngComm, 2013, 15, 1244–1256 | 1253

View Article Online
Paper
CrystEngComm
temperature range of 256–402 uC may related to the decom-
position of two pydc ligands is abruptly burnt by the exothermic
effect (found 28.29, calcd. 31.39%, DTAmax = 283 uC and 499 uC).
For complex 4, the weight loss starts at ca. 45 uC with the
liberation of the uncoordinated six water molecules with a
21
weight loss of 13.57% (calcd. 12.03%, DH = 13.53 kJ mol ). In
the following endothermic and exothermic stages between 90
and 363 uC, the successive weight-loss stages correspond to the
decomposition of en and pydc ligands (DTAmax = 141, 261 and
2
1
3
30 uC, found 55.36, calcd. 56.86%, DH = 289.10 kJ mol ). TG
and DTA study of 5 shows a weight loss of 18.42% from room
temperature to 131 uC, which corresponds to six water
21
molecules (calcd. 17.58%, DH = 32.31 kJ mol ). The anhydrous
complex is thermally stable up to about 278 uC. The last stages
in the temperature range of 278–427 uC are related to the
decomposition of pydc ligands by exothermic effect (found
2
Fig. 9 Photoluminescence emission spectra of 3–5 and pydcH .
4
8.86, calcd. 48.57%, DTA
= 321 and 411 uC, DH = 2115.87 kJ
max
21
mol ). The final products of the thermal decomposition were
identified by IR spectroscopy (CuO for 1 and 2, CdO for 3, CuO +
Ag for 4 and CuO + CdO for 5).
interesting emission of 5 is tentatively assigned as originating
from the ligand-to-metal charge-transfer (LMCT) and/or metal-
to-ligand charge-transfer (MLCT) character, mixed with metal-
centered (ds/dp) states. Ag(I) and Cd(II) complexes usually
show photoluminesence emission but Cu(II) ions in hetero-
metallic complexes caused a quenching effect. Complex 3 may
be a candidate for a light emitting device because of its high
thermal stability and the insolubility in many common
solvents.
The magnetic properties of complexes in the solid state at
room temperature were examined by using a Gouy magnetic
balance. The complexes 1, 2, 4 and 5 exhibit magnetic moment
values of 1.72, 1.73, 1.41 and 1.49 BM, respectively, which
correspond to one unpaired electron The measured values for
Conclusion
In summary, we have successfully prepared five new coordina-
tion polymers built from 2,3-pyridinedicarboxylic acid. These
complexes exhibit structural and dimensional diversity.
Complex 1 exhibits a new unexpected coordination mode of
pydc. Complex 2 is the first dinuclear complex of copper with
pydc, whereas 4 and 5 are also the first 3d–4d heteronuclear
…
complexes. A rare O–H Ag(I) interaction is seen in 4. Complex 4
containing 1D water tapes with T5(2) motif has been obtained.
Water molecule tapes having T5(2) motif are present within the
cavities of the complex and water clusters with hydrogen
bonding contribute to the stability of the complex 4. Complex
5 exhibits rare green emission and the anhydrous form of 5 is
thermally stable up to about 278 uC. These results are expected to
provide new important information for understanding supra-
molecular assemblies of pyridine-2,3-dicarboxylate ligand.
1
and 2 are quite close to the expected value for copper(II)
complexes without interaction. In the case of 4 and 5,
magnetic moments are lower than the expected values for
the copper(II) complexes. This may be attributed to the
antiferromagnetic coupling interaction between neighbouring
Cu(II) ions.
Thermal analyses
Thermal analyses (TG-DTA) were performed to verify the
thermal stability of the complexes. The TGA curves showed
that 1 and 3 were stable up to 196 and 260 uC, respectively. A
total weight loss of 84.20% for 1 and 76.68% for 3 occurred in
the temperature range 196–394 and 260–479 uC, respectively,
presumably due to the endothermic and exothermic removal
of two dmpen for 1 or two emim for 3 and pydc ligands and it
is difficult to assign each weight loss separately (for 1, calcd.
Acknowledgements
This work has been supported by The Scientific and
Technological Research Council of Turkey (TUBITAK, No.
109T201).
2
1
81.6%, DTAmax = 204, 227 and 389 uC, DH = 280.19 kJ mol
;
for 3, calcd. 74.21, DTAmax = 280 and 468 uC, DH = 281.01 kJ
2
1
References
mol ). The thermal decomposition of complex 2 occurs in
three stages. The first degradation stage takes place in the
range of 57–117 uC and it may correspond to the elimination of
two water molecules due to a weight loss of 11.37%, matching
well with theoretical value of 11.37% (DTAmax = 102 uC). The
second stage was attributed to the release of four emim
ligands by giving endothermic and exothermic effects,
respectively (found 40.29%, calcd. 40.48%, DTAmax 227 and
1
S. Ma and H. C. Zhou, Chem. Commun., 2010, 46, 44.
2 L. J. Murray, M. Dinc and J. R. Long, Chem. Soc. Rev., 2009,
38, 1294.
3 R. J. Kuppler, D. J. Timmons, Q. R. Fang, J. R. Li, T.
A. Makal, M. D. Young, D. Yuan, D. Zhao, W. Zhuang and
H. C. Zhou, Coord. Chem. Rev., 2009, 253, 3042.
4 A. U. Czaja, N. Trukhan and U. M u¨ ller, Chem. Soc. Rev.,
2009, 38, 1284.
2
1
2
37 uC, DH = 2129.87 kJ mol ). The last stage in the
1
254 | CrystEngComm, 2013, 15, 1244–1256
This journal is ß The Royal Society of Chemistry 2013

View Article Online
CrystEngComm
Paper
5
S. Takaishi, M. Hosoda, T. Kajiwara, H. Miyasaka,
M. Yamashita, Y. Nakanishi, Y. Kitagawa, K. Yamaguchi,
A. Kobayashi and H. Kitagawa, Inorg. Chem., 2008, 48,
37 Y. Zhou, X. Shen, C. Du, B. Wu and H. Zhang, Eur. J. Inorg.
Chem., 2008, 4280.
38 E. J. Gao, M. C. Zhu, Y. Huang, L. Liu, H. Y. Liu, F. C. Liu,
S. Ma and C. Y. Shi, Eur. J. Med. Chem., 2010, 45, 1034.
39 Q. Yue, J. Yang, G. Li, G. Li, W. Xu, J. Chen and S. Wang,
Inorg. Chem., 2005, 44, 5241.
9
048.
S. Kitagawa, R. Kitaura and S. Noro, Angew. Chem., Int. Ed.,
004, 43, 2334.
6
2
7
8
9
C. Janiak, Dalton Trans., 2003, 2781.
O. Kahn, Acc. Chem. Res., 2000, 33, 647.
S. K. Ghosh, J. Ribas and P. K. Bharadwaj, Cryst. Growth
Des., 2005, 5, 623.
40 W. Starosta and J. Leciejewicz, J. Coord. Chem., 2009, 62,
1240.
41 M. P. Heyes, B. J. Brew, A. Martin, R. W. Price, A.
M. Salazar, J. J. Sidtis, J. A. Yergey, M. M. Mouradian, A.
E. Sadler and J. Keilp, Ann. Neurol., 1991, 29, 202.
42 A. Schurr, C. A. West and B. M. Rigor, Brain Res., 1991, 568,
199.
1
0 B. B. Ding, Y. Q. Weng, Z. W. Mao, C. K. Lam, X. M. Chen
and B. H. Ye, Inorg. Chem., 2005, 44, 8836.
1
1
1
1 G. R. Desiraju, Acc. Chem. Res., 2002, 35, 565.
2 G. Guilera and J. W. Steed, Chem. Commun., 1999, 1563.
3 C. A. Hunter, K. R. Lawson, J. Perkins and C. J. Urch, J.
Chem. Soc., Perkin Trans. 2, 2001, 651.
43 A. Vezzani, R. Serafini, M. Stasi, S. Caccia, I. Conti,
R. Tridico and R. Samanin, J. Pharmacol. Exp. Ther., 1989,
249, 278.
1
1
4 C. Janiak, J. Chem. Soc., Dalton Trans., 2000, 3885.
5 D. Braga, F. Grepioni and E. Tedesco, Organometallics,
44 A. C. Foster, A. Vezzani, E. D. French and R. Schwarcz,
Neurosci. Lett., 1984, 48, 273.
1
998, 17, 2669.
45 R. Schwarcz, W. O. Whetsell and R. M. Mangano, Science,
1983, 219, 316.
46 B. Zhao, X. Y. Chen, P. Cheng, D. Z. Liao, S. P. Yan and Z.
H. Jiang, J. Am. Chem. Soc., 2004, 126, 15394.
47 M. D. Allendorf, C. A. Bauer, R. K. Bhakta and R. J. T. Houk,
Chem. Soc. Rev., 2009, 38, 1330.
48 B. Chen, L. Wang, F. Zapata, G. Qian and E. B. Lobkovsky,
J. Am. Chem. Soc., 2008, 130, 6718.
49 B. Chen, Y. Yang, F. Zapata, G. Lin, G. Qian and E.
B. Lobkovsky, Adv. Mater., 2007, 19, 1693.
1
1
1
6 A. Sediki, F. Lebsir, L. Martiny, M. Dauchez and A. Krallafa,
Food Chem., 2008, 106, 1476.
7 Y. Jin, Y. Che, S. Batten, P. Chen and J. Zheng, Eur. J. Inorg.
Chem., 2007, 1925.
8 M. Mascal, L. Infantes and J. Chisholm, Angew. Chem., Int.
Ed., 2005, 45, 32.
9 R. Ludwig, Angew. Chem., Int. Ed., 2001, 40, 1808.
0 S. Noro, S. Kitagawa, M. Yamashita and T. Wada, Chem.
Commun., 2002, 222.
1
2
2
2
2
1 S. Kitagawa, S. Noro and T. Nakamura, Chem. Commun.,
50 B. D. Chandler, D. T. Cramb and G. K. H. Shimizu, J. Am.
Chem. Soc., 2006, 128, 10403.
51 E. Y. Lee, S. Y. Jang and M. P. Suh, J. Am. Chem. Soc., 2005,
127, 6374.
52 W. J. Rieter, K. M. L. Taylor, H. An and W. Lin, J. Am. Chem.
Soc., 2006, 128, 9024.
53 E. C. Yang, Q. Q. Liang, P. Wang and X. J. Zhao, Inorg.
Chem. Commun., 2009, 12, 211.
54 C. S. Liu, Z. Chang, J. J. Wang, L. F. Yan, X. H. Bu and S.
R. Batten, Inorg. Chem. Commun., 2008, 11, 889.
55 J. He, J. X. Zhang, G. P. Tan, Y. G. Yin, D. Zhang and M.
H. Hu, Cryst. Growth Des., 2007, 7, 1508.
56 K. L. Zhang, F. Zhou, L. M. Yuan, G. W. Diao and S. W. Ng,
Inorg. Chim. Acta, 2009, 362, 2510.
57 L. Wang, L. Duan, E. Wang, D. Xiao, Y. Li, Y. Lan, L. Xu and
C. Hu, Transition Met. Chem., 2004, 29, 212.
58 P. Kanoo, R. Matsuda, R. Kitaura, S. Kitagawa and T.
K. Maji, Inorg. Chem., 2012, 51, 9141.
2
006, 701.
2 B. Hoskins and R. Robson, J. Am. Chem. Soc., 1990, 112,
546.
1
3 S. M. Humphrey, T. J. P. Angliss, M. Aransay, D. Cave, L.
A. Gerrard, G. F. Weldon and P. T. Wood, Z. Anorg. Allg.
Chem., 2007, 633, 2342.
2
2
2
2
4 L. Carlucci, G. Ciani, S. Maggini, D. M. Proserpio and
M. Visconti, Chem.–Eur. J., 2010, 16, 12328.
5 G. H. Wang, Z. G. Li, H. Q. Jia, N. H. Hu and J. W. Xu, Acta
Crystallogr., Sect. E: Struct. Rep. Online, 2009, 65, 1568.
6 M. Andruh, J. P. Costes, C. Diaz and S. Gao, Inorg.Chem.,
2009, 48, 3342.
7 A. Lazarescu, S. Shova, J. Bartolome, P. Alonso, A. Arauzo,
A. M. Balu, Y. A. Simonov, M. Gdaniec, C. Turta, G. Filoti
and R. Luque, Dalton Trans., 2011, 40, 463.
28 M. Li, J. Xiang, L. Yuan, S. Wu, S. Chen and J. Sun, Cryst.
Growth Des., 2006, 6, 2036.
2
9 Z. Yu, G. Li, Y. Jiang, J. Xu and J. Chen, Dalton Trans., 2003,
59 (a) G. M. Sheldrick, SHELXS-97, Program for solution of
crystal structures, University of G o¨ ttingen, Germany, 1997;
(b) G. M. Sheldrick, SHELXL-97, Program for refinement of
crystal structures, University of G o¨ ttingen, Germany, 1997.
60 C. F. Macrae, P. R. Edgington, P. McCabe, E. Pidcock, G.
P. Shields, R. Taylor, M. Towler and J. van De Streek, J. Appl.
Crystallogr., 2006, 39, 453.
61 D. Frenkel and B. Smit, Understanding Molecular
Simulation: From Algorithms to Applications, Academic
Press, San Diego, 2nd edn, 2002.
62 S. Keskin, J. Liu, R. B. Rankin, J. K. Johnson and D. S. Sholl,
Ind. Eng. Chem. Res., 2009, 48, 2355.
63 A. K. Rappe, C. J. Casewit, K. S. Colwell, W. A. Goddard and
W. M. Skiff, J. Am. Chem. Soc., 1992, 114, 10024.
64 V. Buch, J. Chem. Phys., 1994, 100, 7610.
4219.
3
3
0 H. Yin and S. X. Liu, J. Mol. Struct., 2009, 918, 165.
1 T. K. Maji, G. Mostafa, R. Matsuda and S. Kitagawa, J. Am.
Ceram. Soc., 2005, 127, 17152.
3
3
3
2 B. O. Patrick, C. L. Stevens, A. Storr and R. C. Thompson,
Polyhedron, 2003, 22, 3025.
3 Y. Kang, H. Zhang, Z. J. Li, H. K. Cheng and Y. G. Yao,
Inorg. Chim. Acta, 2006, 359, 2201.
4 S. Natarajan, S. Manual, P. Mahata, V. Rao, P. Ramaswamy,
A. Banerjee, A. Paul and K. Ramya, J. Chem. Sci., 2006, 118,
5
25.
5 M. Goher, A. Youssef and F. Mautner, Polyhedron, 2006, 25,
531.
6 M. Frisch and C. L. Cahill, Dalton Trans., 2006, 4679.
3
3
1
This journal is ß The Royal Society of Chemistry 2013
CrystEngComm, 2013, 15, 1244–1256 | 1255

View Article Online
Paper
CrystEngComm
6
6
6
5 S. Y. Jiang, K. E. Gubbins and J. A. Zollweg, Mol. Phys.,
993, 80, 103.
6 A. I. Skoulidas and D. S. Sholl, J. Phys. Chem. A, 2003, 107,
0132.
75 D. R. Turner and S. R. Batten, Acta Crystallogr., Sect. E:
Struct. Rep. Online, 2007, 63, m452.
76 D. M. Roe, P. M. Bailey, K. Moseley and P. M. Maitlis, J.
Chem. Soc., Chem. Commun., 1972, 1237.
77 M. Brookhart, M. L. H. Green and G. Parkin, Proc. Natl.
Acad. Sci. U. S. A., 2007, 104, 6908.
78 L. Infantes and S. Motherwell, CrystEngComm, 2002, 4, 454.
79 D. Braga, F. Grepioni, E. Tedesco, K. Biradha and G.
R. Desiraju, Organometallics, 1997, 16, 1846.
80 A. L. Myers and J. M. Prausnitz, AIChE J., 1965, 11, 121.
81 R. Krishna and D. Paschek, Phys. Chem. Chem. Phys., 2001,
3, 453.
1
1
7 D. Frenkel and B. Smit, Understanding Molecular
Simulation: From Algorithms to Applications, Academic
Press, London, 1996.
¨
6
6
7
8 O. Z. Yesilel, G. G u¨ nay, A. Mutlu, H. Olmez and
O. B u¨ y u¨ kg u¨ ng ¨o r, Inorg. Chem. Commun., 2010, 13, 1173.
9 O. Z. Yesilel, H. Erer and O. B u¨ y u¨ kg u¨ ng ¨o r, Inorg. Chem.
Commun., 2009, 12, 724.
0 Y. Y. Lin, G. H. Chen, Y. P. Yu and B. X. Liu, Acta
Crystallogr., Sect. E: Struct. Rep. Online, 2007, 63,
m2178.
82 A. T. Colak, Y. Sahin, O. Z. Yesilel, F. Colak, F. Yilmaz and
M. Tas, Inorg. Chim. Acta, 2012, 383, 169.
71 H. Aghabozorg, R. Khadivi, M. Ghadermazi, H. Pasdar and
S. Hooshmand, Acta Crystallogr., Sect. E: Struct. Rep. Online,
83 P. Sengupta, S. Ghosh and T. C. W. Mak, Polyhedron, 2001,
20, 975.
2
008, 64, m267.
84 O. Z. Yesilel, G. Gunay, C. Darcan, M. S. Soylu, S. Keskin
and S. W. Ng, CrystEngComm, 2012, 14, 2817.
85 O. Z. Yesilel, A. Mutlu, C. Darcan and O. Buyukgungor, J.
Mol. Struct., 2010, 964, 39.
7
2 S. Martinez-Vargas, R. A. Toscano and J. Valdes-Martinez,
Acta Crystallogr., Sect. E: Struct. Rep. Online, 2007, 63,
m1975.
7
3 S. Shit, J. Chakraborty, S. Sen, G. Pilet, C. Desplanches and
S. Mitra, J. Mol. Struct., 2008, 891, 19.
86 M. Rai, A. Yadav and A. Gade, Biotechnol. Adv., 2009, 27, 76.
87 A. Jurjus, B. S. Atiyeh, I. M. Abdallah, R. A. Jurjus, S.
N. Hayek, M. A. Jaoude, A. Gerges and R. A. Tohme, Burns,
2007, 33, 892.
74 T. Suga and N. Okabe, Acta Crystallogr., Sect. C: Cryst.
Struct. Commun., 1996, 52, 1410.
1
256 | CrystEngComm, 2013, 15, 1244–1256
This journal is ß The Royal Society of Chemistry 2013