A series of coordination networks constructed from the rigid ligand 4,4′-ethynylenedibenzoate: Topological diversity, entanglement, supramolecular interactions and photophysical properties

Article abstract of DOI:10.1039/c7ce00306d

Four coordination networks (CNs), i.e., [Co(edb)(H₂O)(Py)₂], 3; [Cd(edb)(DMSO)₂]·0.5(DMSO), 4; [Er₂(edb)₃(DMSO)₂(H₂O)₂], 5; and [Gd₂(edb)₃(H₂O)₄], 6 (edb^2- = 4,4′-ethynylenedibenzoate), were synthesized and structurally characterized, and the luminescence properties of CNs 4 and 5 were investigated. In CN 3, the ligand adopts a bridging coordination mode that connects one Co(ii) ion to another, resulting in a 1D CN. CNs 4 and 5 contain binuclear centers that are linked to four ligands in the chelating and bridging coordination modes. CN 4 has a 2D → 3D inclined polycatenated structure, whereas CN 5 exhibits a 3D network because the voids created by the long ligand are stabilized by the π-π stacking interactions, thereby avoiding the entanglement of the structure. CN 6 has a paddle-wheel structure with a two-fold interpenetrated rob topology. The photophysical properties of the compound H₂edb and CNs 4 and 5 were studied in the solid state. Compound 2 (H₂edb) displays strong absorption bands at 325 and 350 nm and emission at 385 nm. Upon complexation with Er(III), the emission was quenched. The emissions of CN 4 were due to the intraligand transitions.

Full text of DOI:10.1039/c7ce00306d

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A series of coordination networks constructed from the rigid
ligand 4,4'-ethynylenedibenzoate: topological diversity,
entanglement, supramolecular interactions and photophysical
properties
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
V. Martins,a J. A. L. C. Resendea,b and C. M. Ronconi*a
www.rsc.org/
Four coordination networks (CNs), i.e., [Co(edb)(H2O)(Py)2], 3; [Cd(edb)(DMSO)2]·0.5(DMSO), 4; [Er2(edb)3(DMSO)2(H2O)2],
5; and [Gd2(edb)3(H2O)4], 6 (edb2- = 4,4’-ethynylenedibenzoate), were synthesized and structurally characterized, and the
luminescent properties of CNs 4 and 5 were investigated. In CN 3, the ligand adopts a bridging coordination mode that
connects one Co(II) ion to another, resulting in a 1D CN. CNs 4 and 5 contain binuclear centers that are linked to four
ligands in the chelating and bridging coordination modes. CN 4 has a 2D → 3D inclined polycatenated structure, whereas
CN 5 exhibits a 3D network because the voids created by the long ligand are stabilized by the π-π stacking interactions,
thereby avoiding the entanglement of the structure. CN 6 has a paddle-wheel structure with a two-fold interpenetrated
rob topology. The photophysical properties of the compound H2edb and CNs 4 and 5 were studied in the solid state.
Compound 2 (H2edb) displays strong absorption bands at 325 and 350 nm and emission at 385 nm. Upon complexation
with Er(III), the emission was quenched. The emissions of CN 4 were due to the intraligand transitions.
plays an important role in the structures, pore sizes and
functional applications of CNs.4 In entangled networks, their
individual motifs are interweaved or interlocked, resulting in
Introduction
Coordination networks (CNs) are an important class of
multifunctional hybrid materials that are constructed through
the rational selection of building blocks, such as ligands, metals
and counterions.1 These materials have been used in various
technological applications, including gas storage and
separation, sensing, drug delivery, catalysis and molecular
magnetism, among others.2 However, furnishing CNs with
tailored structures and properties remains a challenge because
predicting the effects of all variables that are involved in the
self-assembly and crystallization processes is difficult. The
optimal choice of metal ions and organic ligands with
controllable characteristics, e.g., the number of binding sites
and their orientation and the ligand denticity, rigidity and
coordination mode, may somewhat overcome this problem.3
Entanglement in CNs is an interesting phenomenon that
periodic architectures with infinite extended array in at least
one dimension.5 Entangled networks can be classified6a as
interpenetrated,6b polycatenated,6c polythreaded6b,c and
polyknotted (self-penetrated),6b,d,e and interpenetrated and
polycatenated networks are the most common entangled
systems.7 According to Carlucci et al., interpenetrated
networks comprise motifs with the same dimensionality as
that of the resulting framework. In polycatenated networks,
the motifs have a lower dimensionality than that of the
resulting structure.8 In addition, each individual motif is
catenated (catena is a Latin word meaning chain) only with the
surrounding motifs but not with all the other motifs.8
Therefore, the individual motifs of the interpenetrated and
polycatenated networks cannot be separated without breaking
the chemical bonds between the atoms. Entanglement may
occur to fill the large pore spaces that are created by wide
voids in the frameworks, thereby increasing the stability of the
whole system.4 This phenomenon relies on supramolecular
interactions, such as hydrogen bonding, π–π stacking
interactions and dispersion forces.9
The ligand 4,4’-ethynylenedibenzoate (edb2-) can adopt a
variety of coordination modes depending on the coordination
habits of the metal ions (Fig. 1).10 In addition, the ligand edb2-
can form different types of entangled structures. To the best
of our knowledge, there are twelve CNs based on edb2-, most
of which are entangled (Table 1). Six of these twelve structures
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were obtained using Zn(II) as the metal cation, of which three interactions can affect the assembly of the entangled
are interpenetrated and, one is polycatenated (Table 1).10 coordination networks.11 To the best of our knowledge, few
Nguyen et al. reacted H2edb and 4,4’-dipyridyl with Zn(II) in investigations have described the role of supramolecular
DMF/H2O under solvothermal conditions and obtained a interactions that are involved in entangled structures that
diamond-like CN possessing
structure of type 3D
3D.10d Song et al. synthesized the CN to investigate the capacity of the elongated dicarboxylate
[Zn2(edb)2(DMSO)2]·1.6H2O using a slow diffusion method and ligand 4,4
-ethynylenedibenzoate (edb2-) (Fig. 1) to furnish new
obtained a polycatenated network of type 2D
3D.10a
a four-fold interpenetrated contain different metal ions. Therefore, our goal in this work is
→
′
→
CNs with the metal ions (Co(II), Cd(II), Er(III) and Gd(III)) and
understand the supramolecular interactions that stabilize the
structures. We obtained two entangled CNs based on Cd(II)
and Gd(II). The Cd(II)-based CN is a polycatenated sql net,
whereas the Gd(III)-based CN is a rare interpenetrated rob net.
Interesting, both coordination networks obtain some
stabilization from the π–π stacking interaction of the triple
bond of the ligand. This interaction is not present in non-
entangled coordination networks. The photophysical
properties of the compound H2edb and CNs
explored in the solid state.
4 and 5 were also
Experimental
Materials and methods
The following compounds were used as received: 4-
iodobenzoic acid, bis(triphenylphosphine)palladium(II)
dichloride, copper(I) iodide, cadmium(II) acetate dihydrate
(98.0 %), cobalt(II) acetate tetrahydrate (98.0 %), erbium(III)
nitrate pentahydrate (99.9 %), calcium hydride, and
trimethylsilylacetylene (TMSA) were obtained from Sigma-
Aldrich, and sodium carbonate, magnesium sulfate, sulfuric
acid, hydrochloric acid, ethyl acetate, methanol, ethanol,
Fig. 1 The ligand edb2- and its common coordination modes: (a) bidentate bis-bridging
mode, (b) tetradentate bis-chelating, (c) tetradentate bis-bridging and (d) tetradentate
chelating-bridging.
dichloromethane,
dimethyl
sulfoxide
and
N,N-
Rigby et al. reacted Zn(NO3)2 and H2edb in DMF at 80 °C,
dimethylformamide were obtained from Vetec/Brazil.
Triethylamine (Sigma-Aldrich) was distilled over CaH2 under Ar.
1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU, Aldrich) was
degassed using the freeze-pump-thaw method prior to use.
Gadolinium(III) nitrate hexahydrate was prepared from 99.9 %
gadolinium oxide (Aldrich/Brazil) following the procedure
described in the Supporting Information.
which yielded an interpenetrated (3D
→ 3D) cubic extended
network with a topology that was similar to that observed in
the IRMOF series.10b Yaghi et al. reacted the ligand H2edb with
Zn(NO3)2 in DMF under solvothermal conditions to obtain a CN
that also had a topology similar to that observed in the IRMOF
isoreticular series. In this CN, the secondary building blocks,
Zn4O(CO2)6, are connected by edb2- moieties, forming a doubly
interpenetrated network (3D
→
3D) with pcu topology.10e
Thin-layer chromatography (TLC) was carried out on
aluminum sheets coated with 60F silica gel (Merck 5554). The
plates were inspected under UV light. The melting points were
determined on a Thermo Scientific 9100 apparatus and are
reported without corrections. The NMR spectra were recorded
by a Varian NMR spectrometer (1H at 500 MHz and 13C at 125
MHz). The solutions were prepared in CDCl3 and DMSO-d6,
which were purchased from Cambridge Isotope Laboratories,
and the residual solvent was used as the internal standard. The
Chen et al. reported the only Zn-based non-entangled CN.
They reacted the ligands H2edb and 2,2’-dipyridyl with Zn(II) in
DMF/MeOH under solvothermal conditions and obtained a 1D
zigzag chain CN.10c
In addition to these Zn-based CNs, Song et al. synthesized a
polyknotted [Eu2(edb)3(DMSO)2(MeOH)2]·2DMSO·3H2O CN.10a
This type of entanglement was also observed in a Co-based
CN, [Co3(edb)3(DMF)4]·2.6DMF, obtained by Chen et al.10c
Arguably, the elongated and rigid nature of the ligand edb2-
appears to favor the formation of entangled structures.
Noticeably, the reaction conditions and the supramolecular
chemical shifts are expressed as
δ
constants (J) are expressed
values, and the coupling
in Hertz.
2 | J. Name., 2012, 00, 1-3
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Table 1. List of CNs based on the ligand edb2- as described in the literature
Coordination network (CN)
[Eu2(edb)3(DMSO)2(MeOH)2]·DMSO·3H2O
[Zn2(edb)2(DMSO)2]·1.6H2O
[Zn(edb)(BIPY)]
Dimensionality
Entanglement
Reference
10a
3D
2D
3D
3D
2D
1D
2D
3D
3D
3D
3D
3D
Polyknotted
Two-fold 2D → 3D inclined polycatenated
Four-fold 3D → 3D interpenetrated
Two-fold 3D → 3D interpenetrated
Not observed
10a
10d
[Zn4O(edb)3(H2O)2]·6DMF
[Co3(edb)3(DMF)4]·2.6DMF
[Zn(edb)(bpy)]·x(Solvent)
[Cu(edb)(bpy)]·x(Solvent)
[Co2(edb)3(bpy)2]·3DMF·H2O
[Zn4O(edb)3]·(DMF)17(H2O)7
[ZrO4(OH)4(edb)6
10b
10b
Not observed
10c
Not observed
10c
Polyknotted
10c
Two-fold 3D → 3D interpenetrated
Not observed
10e
10f, g
10f
[HfO4(OH)4(edb)6
Not observed
[Zn8O2(TPA)2(BDC)(EDDB)2]
Not observed
10h
The following abbreviations are used for signal graphite monochromated Mo K
multiplicities: s, singlet; d, doublet; t, triplet; and m, multiplet. The data were integrated using the EVALCCD program12, and a
α radiation (λ = 0.71073 Å).
Fourier transform infrared (FTIR) spectra were recorded from semiempirical absorption correction was carried out using the
4000–400 cm-1 from KBr pellets on a Varian FTIR-7000 SADABS program.13 The single-crystal X-ray data for CNs
5
and
were collected by a Bruker D8 Venture diffractometer using
the bands: vs, very strong; s, strong; m, medium; and w, weak. Mo K = 0.71073 Å) radiation. CNs and were mounted
The diffuse reflectance UV-Vis spectra of the solid samples on a MiTeGen loop using silicone grease. The measurement of
diluted in BaSO4 (Aldrich) were recorded by a Cary 5000 UV- CN was carried out at 150 K. The data collection, data
spectrometer. The following nomenclature was used to assign
6
α
(
λ
3
6
6
Vis-NIR absorption spectrometer. The emission spectra were reduction and cell refinement were performed using APPEX2
acquired by an FLS980 fluorescence spectrometer from (Bruker AXS, 2005), and absorption corrections were
Edinburgh Instruments. The fluorescence quantum yields of performed using SADABS.13 All structures were solved using
the solid samples were determined using an integration the direct method and refined using the full-matrix least-
sphere. Fluorescence lifetime measurements were performed squares method in the SHELX-97 program package.13 Non-
on a laser table. A quartz cuvette for solids containing the hydrogen atoms were refined with anisotropic displacement
powdered compounds was irradiated using a third-harmonic parameters, and the hydrogen atoms were positioned
(355 nm, 185 mJ) Nd-YAG pulsed laser (Quantel BRILLIANT-B). geometrically using the riding model. All structures displayed
The emissions were collected at 90 ° to the excitation on an large solvent-accessible voids, which are presumably filled with
Oriel CornerstoneTM 260 1/4
m monochromator at the several disordered molecules of DMSO, DMF, H2O and
selected wavelengths and detected using a PMT (Oriel 77360, pyridine. The attempts to locate and refine the solvent peaks
rise time = 1.2 ns). The signals were captured using an were unsuccessful. Therefore, the PLATON-SQUEEZE program
oscilloscope (LeCroy Wavesurfer 44MXs-B, 400 MHz).
was used to remove those peaks and improve the atomic
Elemental analyses were conducted using a Perkin Elmer model.14 The PLATON-SQUEEZE routine reports that the total
CHN 2400 analyzer at the Central Analítica, Instituto de solvent-accessible void volumes (per unit cell) are 2303 (for CN
Química, USP-São Paulo, Brazil. Crystallizations were carried
out in a Memmert cooled incubator, model IPP 400.
3
), 1086 (for CN
5
), and 9241 Å3 (for CN
: two DMSO and one pyridine; CN
: eight DMF) were severely
6
). The lattice solvent
molecules (CN
3
5: two
The thermogravimetric analysis (TGA) was carried out using DMSO and one H2O; CN
6
a Shimadzu TGA-60 instrument with aluminum crucibles over a disordered and could not be modeled satisfactorily. The total
range of 30 – 600 °C at a heating rate of 10 °C min-1 under a electron count per unit cell removed by this routine was 568
nitrogen gas flow of 30 mL min-1.
for CN
correspond to 142 (Z = 4 for CN
(Z = 8 for CN ) electrons per asymmetric unit. The solvent-
3 and 4 were accessible void volumes and the electron count values
3
, 234 for CN
5
and 2569 for CN
6
. These values
3
), 117 (Z = 2 for CN
5
) and 321
Crystallography
6
Single-crystal X-ray diffraction data for CNs
collected by a Bruker Kappa CCD diffractometer equipped with matched well with the calculated values.
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Topological analysis of the CNs was carried out using the
ToposPro 5.0.4.1 package.15
[Gd2(edb)3(H2O)4], 6. M = [Gd(NO3)3].6H2O (25.3 mg, 56.2
μmol), S = DMF. Transparent crystals were collected from the
Powder XRD measurements were carried out by a Bruker solution (26.5 mg, 40 %). FTIR
ν
(cm-1): 3379 (m), 1660 (m),
D8 Advance diffractometer with Cu Kα radiation (λ = 1.54184 1608 (s), 1583 (vs), 1525 (s), 1417 (s), 1384 (s), 1298 (m), 1284
Å). All data were acquired at room temperature over a 2θ (m), 1178 (w), 1097 (w), 1014 (w), 864 (m), 829 (w), 785 (s),
range from 4 to 50° with a step of 0.02° and a counting time of 700 (m), 679 (m), 628 (m), 567 (w), 511 (w), 461 (w), 405 (m).
0.5 sec/step.
Elemental analysis calculated for C48Gd2H32O16: C 48.89 %, H
2.74 %; experimentally determined: C 36.69 %, H 2.74 %.
Ligand preparation
The ligand was synthesized according to a procedure
previously reported in the literature with minor modifications
as described in the ESI†.10d
Results and discussion
Syntheses
The Sonogashira cross-coupling reaction was carried out
following the procedure described in the literature with minor
modifications.10d For the synthesis of 4,4’-ethynylenedibenzoic
General procedure for synthesizing coordination networks (CNs) 3
and 4
acid (H2edb, compound 2) (Scheme 1), 4-iodobenzoic acid was
A solution of the metal salt M (0.75 mmol) in 15 mL of
MeOH was added dropwise to a beaker containing 25 mL of a
solution of H2edb (0.20 g, 0.75 mmol) in DMSO. This beaker
was then inserted into a large vial containing 5 mL of a base B.
The vial was sealed and left undisturbed for five days for
crystal formation.
methylated, and the resulting ester (methyl 4-iodobenzoate)
was cross-coupled via the Sonogashira reaction to afford
dimethyl 4,4’-ethynylenedibenzoate
into H2edb via a basic hydrolysis, followed by acidification
with HCl. Compound was then reacted with the metal
cations to afford
[Cd(edb)(DMSO)2]·0.5(DMSO)
and [Gd2(edb)3(H2O)4]
1, which was converted
2
2
CNs
[Co(edb)(H2O)(Py)2]
3
,
,
[Co(edb)(H2O)(Py)2], 3. M = [Co(OAc)2].4H2O (0.19 g, 0.75
mmol), B = pyridine. Pink crystals were formed after five days
4, [Er2(edb)3(DMSO)2(H2O)2]
5
6
(Scheme 1).
(0.29 g, 68 %). FTIR
ν
(cm-1): 3381–3224 (m), 1630 (m), 1606
Fourier transform infrared spectroscopy (FTIR)
The FTIR spectrum of compound displays a broad O–H
(m), 1581 (m), 1537 (m), 1487 (w), 1446 (m), 1386 (vs), 1284
(w), 12717 (w), 1178 (w), 1153 (w), 1095 (w), 1070 (w), 1040
(w), 1014 (m), 952 (w), 862 (m), 802 (m), 783 (s), 756 (w), 698
(m), 630 (m), 511 (w), 426 (w). Elemental analysis calculated
2
stretching band in the region of 3200–2200 cm-1, which
suggests that the molecules might exist as dimers in the solid
state (Fig. S1, ESI†).16 This broad band displays various sub-
maxima due to the C–H stretching modes of the aromatic ring.
The band at 1673 cm-1 can be attributed to the C=O stretching
vibrations. This band contains a shoulder at approximately
1635 cm-1. A deconvolution analysis of this band revealed two
bands centered at 1673 and 1635 cm-1, supporting the
for C32CoH40N2O9S3:
C 51.12 %, H 5.36 %, N 3.73 %;
experimentally determined: C 51.63 %, H 3.96 %, N 1.675 %.
[Cd(edb)(DMSO)2]·0.5(DMSO), 4. M = [Cd(OAc)2].2H2O
(0.33 g, 0.75 mmol), B = Et3N. Transparent single crystals were
formed after five days (0.19 g, 63 %). FTIR
ν
(cm-1): 3350–3238
(m), 1606 (s), 1577 (s), 1531 (s), 1512 (s), 1406 (s), 1384 (vs),
1284 (m), 1172 (m), 1140 (m), 1099 (m), 1012 (m), 970 (w),
866 (s), 827 (m), 787 (s), 704 (m), 642 (m), 513 (m), 457 (w),
403 (m). Elemental analysis calculated for C42Cd2H46O12S5: C
44.72 %, H 4.11 %; experimentally determined: C 40.43 %, H
3.37 %.
presence of dimeric species in compound 2 16
Upon
.
coordination to the metal ions, the band at 1673 cm-1, which
are attributed to the C=O stretching vibrations, shifted to
wavenumbers that were lower than those of compound
2 (Fig.
S2, ESI†). In addiꢀon, the broad band, which is attributed to
the O–H stretching vibrations, of the carboxylic group at 3200–
2200 cm-1 disappeared from the spectra of the CNs, indicating
General procedure for the synthesis of coordination networks
(CNs) 5 and 6.
that compound 2 had been deprotonated and had coordinated
to the metal ions.17 A broad band in the range of 3700–2900
cm-1 of the CNs indicates the presence of adsorbed or
crystallized water molecules.18
A solution of the metal salt M (56.2 μmol) in 1.5 mL of
MeOH was added dropwise to a scintillation vial containing 2.5
mL of a solution of H2edb (10.0 mg, 37.5 μmol) in the solvent S.
The mixture was heated to 60 °C for three days in an incubator
and then cooled to 10 °C at 0.4 °C min-1.
Structural description of the coordination networks (CNs)
[Er2(edb)3(DMSO)2(H2O)2], 5. M = [Er(NO3)3].5H2O (24.9
mg, 56.2 μmol), S = DMSO. Pink single crystals were collected
The data collection and structural refinement of CNs
, and are summarized in Table 2.
3, 4,
5
6
from the solution (12.1 mg, 32 %). FTIR
ν
(cm-1): 3579 (w),
3350 (w), 3072 (w), 1608 (s), 1580 (s), 1351 (s), 1413 (vs), 1301
(m), 1284 (m), 1180 (m), 1097 (w), 1016 (m), 862 (m), 817 (w),
783 (s), 698 (m), 624 (m), 565 (w), 507 (w), 463 (w). Elemental
analysis calculated for C26ErH19O8S: C 47.40 %, H 2.91 %;
experimentally determined: C 32.27 %, H 2.95 %.
Crystal structure of [Co(edb)(H2O)(Py)2], 3. The single-crystal
X-ray structural analysis revealed that CN crystallizes in the
3
monoclinic space group C2/c. The asymmetric unit of CN
3
contains one Co(II) ion, a half-deprotonated ligand (edb2-), two
pyridine molecules and two water molecules, all of which are
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localized in a two-fold rotational axis, as well as a glide and bidentate bis-bridging mode (Fig. 1a). The axial positions are
several intensely disordered solvent molecules, which were occupied by two nitrogen atoms from the pyridine molecules
not posiꢀoned in the asymmetric unit (Fig. S3, ESI†).
(N1 and N2). The ligand edb2- connects one metal center to
Co(II) has an octahedral geometry, and the equatorial another to form a 1D chain (Fig. 2b). The Co–O and Co–N bond
positions are occupied by two oxygen atoms from the water lengths (Table S1, ESI†) vary from 2.074(2) Å to 2.128(2) Å and
i
molecules (O1w and O1w ) and two oxygen atoms (O1 and O1i) from 2.180(3) Å to 2.183(46) Å, respectively, and agree with
from two edb2- units (Fig. 2a) that are coordinated in a the related bonding parameters of other cobalt compounds.19
Scheme 1. Synthetic route employed to obtain the compound H2edb and the CNs.
Table 2. Crystallographic data for the CNs synthesized in this work
3
4
5
6
Chemical formula
Formula mass
Crystal system
Space Group
Temperature (K)
a (Å)
C26CoH22N2O6
517.39
C42Cd2H46O12S5
1127.95
Monoclinic
C2/c
C26ErH19O8S
658.73
Triclinic
Gd2C48H32O16
1179.24
Monoclinic
C2/c
Monoclinic
C2/c
P1
̅
293(2)
293(2)
287(2)
150(2)
10.337(2)
15.507(3)
27.383(6)
90
32.978(7)
7.9043(16)
19.738(4)
90
8.1941(5)
16.2658(9)
16.7088(9)
78.246(2)
87.041(2)
84.491(2)
2169.1(2)
2
35.067(3)
24.035(3)
26.081(3)
90
b (Å)
c (Å)
α (°)
β (°)
96.84(3)
90
106.77(3)
90
132.07(9)
90
γ (°)
V (Å3)
4358.0(15)
4
4926.2(19)
8
16319(3)
8
Z
μ (mm-1)
0.418
1.132
2.010
1.652
Reflections/unique
Rint
17440/3980
0.0597
78928/4511
0.0809
31069/8558
0.0562
57136/14826
0.0675
R1a/wR2a (I ≥ 2σ(I))
R1/wR2 (all data)
GOOF
0.0578/0.2179
0.0822/0.2431
0.915
0.0300/0.0621
0.0441/0.0674
1.085
0.0339/0.0790
0.0470/0.0842
1.032
0.1425/0.3908
0.1879/0.4313
1.062
aR1 = ∑||Fo| – |Fc||/∑|Fo|, wR2)= [∑w(Fo2 – Fc2)2/∑w(Fo2)2]1/2
Both the pyridine and water molecules coordinated to coordinating in chelating or other modes (Fig. 2a). The
Co(II) in the axial and equatorial positions and prevented the distance between O1wi and O2 is 2.636(6) Å.
growth of the polymer into dimensions (Fig. 2a) that were
The CNs that were constructed with the elongated ligands,
higher than those obtained. The main intermolecular such as edb2-, can display entanglement.4 To the best of our
interacꢀons are summarized in Table S2, ESI†. The water knowledge, two Co-based CNs that were constructed using the
molecule participates in a strong hydrogen bond with the edb2- ligand have been reported in the literature (Table 1); one
i
i
ligand (O2···H1wb –O1w ), preventing the latter from
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2D CN was described by Rigby et al. in 201210b, and another 3D formation of secondary units and, therefore, the construction
polyknotting CN was obtained by Chen et al. in 2015.10c of CNs with enhanced dimensionality.20
CN , however, is 1D, with no entanglement (Fig. 2b). To CN also crystallizes in the monoclinic space group C2/c (Table
stabilize the whole network, the chains of CN pack in a 3D 2). The asymmetric unit contains one fully deprotonated ligand
3
4
3
array, resulting in a 3D supramolecular structure. This packing edb2-, two DMSO molecules that are coordinated to Cd(II) and
essentially involves the following two different types of a half-lattice DMSO molecule in a two-fold rotation axis (Fig.
hydrogen bonds: C4–H4···O2 and O2·· H14···O2 (bifurcated) S4, ESI†). The Cd(II) cation is hexacoordinated and adopts a
(Fig. 2c and Table S2, ESI†). The first interaction involves the distorted octahedral geometry with the oxygen atoms from
hydrogen atom from the benzene ring of the ligand and the the DMSO molecules in the axial position and the oxygen
oxygen atom from the carbonyl group, resulting in a dimer atoms from the ligand edb2- in the equatorial position (Fig. 3).
with a distance of 3.607(6) Å. The second interaction consists The Cd–O bond lengths (Table S3, ESI†) vary from 2.247(3) Å to
of an array of the following three atoms: one hydrogen atom 2.435(3) Å and are consistent with the values found in the
from a pyridine molecule and two oxygen atoms from the literature.19 The distance between the two Cd(II) ions is
carbonyl groups of the ligand edb2-, forming a bifurcated 4.174(1) Å. The ligand adopts the tetradentate bis-chelating
hydrogen bond with a distance of 3.380(9) Å (Table S2, ESI†).
(Fig. 1b) and tetradentate bis-bridging (Fig. 1c) coordination
modes. Two metal centers, four edb2- units in the equatorial
Structure of [Cd(edb)(DMSO)2]·0.5(DMSO), 4. Changing position and four DMSO molecules in the axial position form a
pyridine to triethylamine and Co(II) to Cd(II) in the synthesis subunit named Cd2(CO2)4(DMSO)4. This subunit has four
yielded the 2D CN
found. 4). Pyridine participates in the coordination in CN
while triethylamine does not coordinate to Cd(II) in CN , most carboxylate group participates in a hydrogen bond with
4
(Fig. 3 andError! Reference source not extension points that orientate the network growth in a 2D
3,
square grid (Fig. 3 and 4). Notably, oxygen O1 of the
4
likely because of its higher steric hindrance. Cadmium is largely hydrogen H3 attached to carbon C3 of the aromatic ring,
used to construct the CNs with carboxylate ligands because of stabilizing the formed subunit, Fig. 3.
its high coordination number. This feature facilitates the
Fig. 2 (a) Coordination environment of Co(II) in CN 3; (b) perspective view of the 1D chain; (c) 3D supramolecular framework and the main intermolecular interactions involved in
these assemblies. The hydrogen atoms are omitted for clarity. The symmetry code for equivalent positions is as follows: (i) 1–x, y, 1/2–z; (ii) 2–x, y, 1/2–z; (iii) -1/2+x, -1/2+y, z; and
(iv) 3/2–x, -1/2+y, 1/2–z.
6 | J. Name., 2012, 00, 1-3
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The literature contains reports of 11 compounds based on contribute to the polycatenation of the layers in CN
Cd(II) and carboxylate ligands that contain the same subunit In addition to this interaction, the piling of the layers can be
obtained in this work, Cd2(CO2)4(solvent)4 (solvent = H2O, DMF attributed to numerous weak short interactions, such as C1D2
4 (Fig. 5).
–
and MeOH), which are surprisingly all 0D coordination H1DB···O1D1 and C4–H4···S1D2 (Fig. 5 and Table S4, ESI†). A
compounds.21 This is an interesting result because a variety of weak hydrogen bond C6–H6···π also exists between hydrogen
CNs and topologies can be designed from this subunit. A H6 on
topological analysis of 4 was carried out using the ToposPro
5.0.4.1 package25 considering the subunits Cd2(CO2)4(DMSO)4
as 4-connected nodes.
CN
4 is a 4-connected uninodal net of sql type with point
(Schläfli) symbol (44·62) (Fig. 4). The sql net is one of the most
frequent in the coordination networks. An interesting feature
of the sql-type net is its tendency to form polycatenated
structures when the sizes of the square grids are large enough
for two or more related nets to interweave with each other.3f
Indeed, the grids of the 2D CN
4 stack and interlock with each
other (Fig. 4) due to the elongated nature of the ligand edb2-
and the supramolecular interactions that are present in the
structure (Fig. 5 and Table S4, ESI†). The interlocking between
the 2D nets produces a 3D polycatenated inclined structure
Fig. 3 Tetra-coordinated subunit Cd2(CO2)4(DMSO)4 in CN 4
. The ligand edb2-
(2D + 2D
→ 3D) with the layers showing an inclination of
adopts the following two coordination modes: tetradentate bis-chelating and
tetradentate bis-bridging. Symmetry code for equivalent positions is as follows:
(i) 1/2–x, 1.5–y, and 1–z.
approximately 134°, as measured between the two planes
through the layers, and a solvent-accessible void of 815 Å3.
The short distance of 3.952 Å between carbons C8 and C16
of the triple bond suggests that π-π stacking interactions may
Fig. 4. (a) The polycatenated (2D + 2D → 3D) network in CN 4 and (b) its topological representation.
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Fig. 5 (a) Intermolecular interactions involved in the polycatenated CN 4 and (b) its piling. Symmetry code for equivalent positions is as follows: (i) x, -1+y, z; (ii) x, 1-y, -1/2+z; (iii)
1/2-x, -1/2+y, 1/2-z; and (iv) x, 1-y, 1/2+z.
the aromatic ring of one molecule and the centroid Cg formed synthesized in this work. Indeed, the void space in the Zn(II)-
by carbons C10–C15 of the adjacent molecule. All these based CN is 523 Å3, whereas in CN , the void space is 815 Å3.
4
supramolecular interactions may contribute to the stability of
the whole system.
Chen et al. reported a sql CN based on Cu(II) and the ligand
edb2- containing a Cu2(CO2)4(bpy)2 (bpy = 2,2’-bipyridine)
Using the ligand edb2- and Zn(II), Song et al. obtained a 2D subunit.10c In addition to the elongated nature of the ligand
CN with a Zn2(CO2)4(DMSO)2 paddle-wheel subunit.10a Similarly edb2-, entanglement of the Cu(II)-based CN did not occur. The
to the CN
4
obtained in this work, this Zn(II)-based CN is a 3D steric hindrance caused by the 2,2’-bipyridyl moiety prevented
, in which the entanglement of the sql layers.
polycatenated inclined sql net. However, unlike CN
4
there is a π-π stacking interaction related to the triple bond
(the short distance is approximately 4.0 Å), in the Zn(II)-based
Structure of [Er2(edb)3(DMSO)2(H2O)2], 5. To enhance the
CN, this interaction is between the aromatic rings of the ligand dimensionality of the network, metal cations with higher
(the short distance is 3.5 Å). Most likely, the stronger coordination numbers and flexible coordination modes, such
interaction between the layers in the Zn(II)-based CN obtained as lanthanides, can be employed.22 In this work, we obtained
by Song et al. may decrease the void space compared to CN
4
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Fig. 6 (a) Coordination environment of the Er(III) ion in CN 5. (b) Four connected Er2(CO2)6(DMSO)2 subunits. (c) Representation of the 2D CN. (d) Representation of the topology of
CN 5. Symmetry code for equivalent positions is as follows: (i) 3–x, 1–y, –1–z and (ii) 2–x, 1–y, –z.
an Er-based CN
[Er(NO3)3] 5H2O and H2edb (Fig. 6).
To the best of our knowledge, CN
constructed using the ligand edb2-. CN
5
from
a
DMSO:MeOH solution of antiprism geometry (Fig. 6a). The geometry involves one aqua
·
oxygen atom, one oxygen atom from DMSO and six oxygen
5
is the first Er-based CN atoms from the edb2- units. The ligand edb2- is coordinated to
5
crystallizes in the the central ion in the tetradentate chelating-bridging (Fig. 1d)
ꢀ
1 space group. The asymmetric unit consists of one- and tetradentate bis-chelating modes (Fig. 1b). The Er−O bond
triclinic P
and-a-half edb2- units, one Er(III) ion, one DMSO molecule, one lengths are in the range of 2.250(5) to 2.438(5) Å (Table S5,
water molecule and several disordered solvent molecules that ESI†), which are comparable to the values found in the
were not positioned in the asymmetric unit (Fig. S5, ESI†). The literature.19
Er(III) ions are octa-coordinated, showing a distorted square
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Fig. 7 (a) Hydrogen bonds involved in the stacking of the nets. (b) Weak C–H···O bond of the ligand. Symmetry code for equivalent positions is as follows: (i) 3–x, 1–y, –1–z and (ii)
2–x, 1–y, –z.
The water molecule O1W–H1WA participates in a hydrogen
bond in which the acceptor is oxygen O5 of the carbonyl group bonding, O1W–H1WB···O1, between water molecules and the
in the ligand (Fig. 6b and Table S6, ESI†). CN forms a oxygen atom of a carboxylate group in an adjacent network
The 3D supramolecular network in CN 5 packs via hydrogen
5
paddlewheel-like subunit with four extension points that (Fig. 7a). Additionally, there is a C13–H13···O2 hydrogen bond
directs the growth of the framework in two dimensions (Fig. between the hydrogen of the methyl group in DMSO C13–H13
6b), resulting in a 2D stair-like network (Fig. 6c and e) with a and oxygen O2 of the carboxylate group in the ligand (Fig. 7a).
solvent-accessible void of 1069 Å3.
The ligand is slightly bent to allow for a hydrogen bond, C4D1–
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H4DB···O5, between the hydrogen of the aromatic ring and the
oxygen of the carbonyl group (Fig. 7b).
The topological analysis of CN
5 using the ToposPro 5.0.4.1
package15 revealed a uninodal 5-connected cem net with a
point (Schläfli) symbol of (33·44·53) (Fig. 7d and f). To the best
of our knowledge, this is the first example in which the ligand
edb2- was used to construct a coordination network with a rare
uninodal 5-connected cem topology (Table 1).
Structure of [Gd2(edb)3(H2O)4], 6. CN
6 crystallizes in the
monoclinic C2/c space group. The asymmetric unit consists of
three edb2- units, two independent Gd(III) ions and four
coordinated water molecules (Fig. S6, ESI†). The Gd(III) ions
adopt
a distorted square antiprism geometry that is
coordinated to four edb2- units in bridging the mode, one edb2-
in the chelating mode and two water molecules (Fig. 1b and c).
The bridging coordination mode of the ligands connects the
two metal centers, forming a Gd2(CO2)6(H2O)4 subunit in a
paddle-wheel arrangement (Fig. 8). The distance between the
two Gd(III) ions is 4.373(2) Å, and the Gd–O bond lengths vary
from 2.287(14) Å to 2.526(13) Å (Table S7, ESI†).
The four edb2- units coordinated in the bridging mode that
connect the two Gd(III) ion extend the growth of the network
in two dimensions, whereas the two edb2- units coordinated in
the chelating mode extend the dimensionality in a third
dimension (Fig. 9a).
Fig. 8 Gd2(CO2)6(H2O)4 subunit of CN 6 in a paddle-wheel arrangement. Symmetry code
for equivalent positions is as follows: (i) x, 1 – y, – 1/2 – z; (ii) x, 2 – y, 1/2 – z; and (iii)
1/2 – x, – 1/2 + y, z.
The primary intermolecular interactions that appear to
dictate the growth of this network are weak π–π stacking
interactions between the C9 and C40 atoms of the triple bond
(Fig. 9c and d, Table S8, ESI†).
The topological analyses reveals that CN
6 can be classified
To the best of our knowledge, only three lanthanide-based
CNs using the ligand edb2- ligand have been reported, two of
which were reported in this work. Therefore, although this
ligand has been previously used to form CNs, research on
lanthanides and edb2- remains scarce.
as a 6-connected rob (Fig. 9b) network with a point (Schläfli)
symbol of (48·66·8) (Fig. 9b).23 The rob net can be visualized as
a distorted octahedral node (usually a metal ion or metal
clusters) connected through to 2-connected linkers (usually
the organic ligands).23a The occurrence of entanglement in the
rob topology is influenced by a distortion of their coordination
figures (nodes) and the length of the spacers.23a The rob
topology is commonly observed in the literature as a self-
interpenetrating network in which the six-membered shortest
circuits are penetrated by rods of the same net23b-i The self-
Powder X-ray diffraction (PXRD) and thermogravimetric
analysis (TGA)
PXRD studies were carried out to evaluate the structural
stability and phase purity of the CNs synthesized in this work
(Fig. S7, ESI†). During the collection of the single-crystal X-ray
penetration appears to be favored when flexible and long
23b-i
data, crystal decay was observed in CNs
3 and 6. Therefore, to
linkers are used.
However, rob nets displaying
avoid solvent loss, the crystals were mounted on a MiTeGen
loop using silicone grease, and the single-crystal X-ray
interpenetration are rarely observed.23j,k Therefore, in this
work, we obtained a rare two-fold interpenetrated net (3D +
measurements were conducted at a low temperature. CNs
and lost their crystallinity after 15 minutes (Fig. S7a and d,
ESI†). In contrast, CNs and were very stable over time, and
3
3D
penetrated by the rods of the related net (Fig. 9b).6
The solvent-accessible void in CN
is 9051 Å3, which is the
→ 3D) in which the six-membered shortest circuits are
6
4
5
6
their PXRD patterns matched the simulated patterns that were
calculated from the single-crystal X-ray diffraction data,
indicating the phase purities of these CNs, (Fig. S7b and c,
ESI†). The difference in the intensity can be attributed to the
preferred orientation of the crystalline powder samples.
highest of all the CNs reported in this work.
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Fig. 9 (a) 3D packing of CN 6 and (b) the resulting rob topology. (c) and (d) Self-interpenetration of the networks involving π···π stacking.
The TGA studies revealed that compound
to decompose above 300 °C (Fig. S8a, ESI†). CN
weight loss of approximately 34.5 % from 30 to 275 °C, which range of 30 – 480 °C (
2
(H2edb) begins approximately 30 % (
5
) and 24 % (
6
) due to the loss of
3
underwent a adsorbed water and solvent molecules in their lattices in the
) and 30 – 450 °C ( ), followed by ligand
) and 450 °C ( ) (Fig. S8 d and e,
5
6
is related to the loss of water and pyridine molecules, and a decomposition above 480 °C (
second weight loss of 42 % at 390 °C, which is attributed to the ESI†).
decomposition of the 4,4'-ethynylenedibenzoate ligand (Fig.
5
6
Solid-state photophysical studies
The normalized diffuse reflectance UV-Vis and
(Fig. S8c, ESI†), and a 5 % weight loss at 220 °C, which that was photoluminescence spectra of compound and CNs and in
most likely due to the loss of DMSO molecules. The the solid state at room temperature are shown in Fig. 10 and
decomposition of the ligand occurs above 390 °C. CNs and Table 3. The photophysical properties of CNs and were not
S8b, ESI†). CN
4 underwent a 26 % weight loss from 30 to 100
°C, which is attributed to the loss of adsorbed water molecules
2
4
5
5
6
3
6
displayed two consecutive weight losses as follows: a loss of
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investigated because their structures were not stable when 10. Because the molecule is highly conjugated, the transitions
exposed to air.
in the absorption spectrum might be related to the π–π*
electron transfer that involves the aromatic ring and adjacent
triple bond.24
Compound
2
exhibits a blue emission (
λ
λ
em(3) = 385 nm)
max(3) = 325 nm
when excited at the absorption maximum
with a high quantum yield (Φem = 0.45) as shown in Table 3. A
low Stokes shift occurred for compound 2, indicating a low
geometry change upon excitation due to its structural rigidity
in the solid state. The lifetime (τ) of compound 2 in the solid
state synthesized in this work is 5.61 ns (Table 3 and Fig. S9,
ESI†). The lifetimes for the ligand in the ester form measured
in different solvents reported in the literature are
MeCN; 0.72 ns in C6H12; and 0.64 ns in CH2Cl2.25 The higher
lifetime measured for the acid form of compound compared
τ = 0.61 ns in
2
to the values reported in the literature for this compound in
the ester form in solution is consistent with the fact that the
infrared spectrum (Fig. S1, ESI†) of compound
2 indicates the
presence of dimeric species in the solid state, which increases
the rigidity of the structure and reduces nonradiative decay
processes. In addition, a shorter lifetime is expected in solution
than in the solid state due to the interaction with the
surrounding solvent molecules, which can increase the
efficiency of energy transfer.
Table 3 Photophysical data obtained for compounds 2, 4 and 5 in the solid state
and at room temperature
Stokes
shiftb
Cpd
2
λ
abs (1)a
λ
abs (2)a
λ
abs (3)a
λema, τ (ns)
Φ
245
235
230
325
305
305
350
360
330
385, 5.61
444, 6.37
586, 7.16
20.66
0.45
0.057
-
4
8.920
-
5
-
-
a Wavelengths given in nm
b Stokes shift given in eV
CN
nm and a strong band at 305 nm (Fig. 10b and Table 3) due to
the ligand transitions. Excitation at = 305 nm resulted in a
strong emission at em = 444 nm and two weak emission bands
at 414 nm and 500 nm. These emission bands can be
attributed to the intraligand (IL) charge-transfer *–
transitions. The lifetime (Table 3) measured for CN in the
solid state is 6.37 ns (λem = 444 nm). CN also produces an
emission band at 586 nm ( = 7.16 ns, Table 3) under excitation
at 305 nm, which is not observed for compound . This
emission might be associated with metal-perturbed intraligand
transitions (MPIL).26, 27 The higher lifetimes for CN
than the
lifetime of the ligand H2edb (compound ) might be related to
4 shows two weak absorption bands at 235 nm and 360
λ
λ
π
π
4
4
τ
2
4
2
the coordination of the ligand to various Cd(II) centers and also
to the intermolecular interactions, such as π–π stacking and C–
H···π interactions, which can increase the rigidity of the
network, thus reducing non-radiative energy loss. The
Fig. 10 Photoluminescence absorption (dashed lines) and emission (thick lines) spectra
of compounds 2 (a), 4 (b) and 5 (c).
quantum yield of CN
Φem = 0.0574), which might be also associated to the
presence of several Cd(II) centers in the network.27
4 was much lower than that of compound
Compound
2 displays a weak shoulder at 243 nm and two
2
(
strong absorption bands at 325 and 350 nm as shown in Fig.
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Journal Name
the nature of the topology and the stair-like fashion of the
network, which stabilizes the whole structure. The emission of
Table 4 Main absorption bands attributed to the f-f transitions observed in CN
5
Transition
4I15/2 to 4G11/2
4I15/2 to 4F3/2
λ
abs (2) (nm)
379
CN
5
was quenched due to vibronic coupling.
CN 6 displays a rare 3D interpenetrated rob topology in
407
which the Gd2(CO2)6(H2O)4 subunit acts as a distorted six-
connected node, and the ligand acts as a two-connected node.
Networks with rob topology usually display self-catenation,
and interpenetration rarely occurs. The interpenetration was
also stabilized by a π···π interaction between the triple bond of
4I15/2 to 4F5/2 + 4F3/2
4I15/2 to 4F7/2
4I15/2 to 2H11/2
4I15/2 to 4S3/2
451
488
523
544
the ligand, as observed in CN
4. Interestingly, the non-
4I15/2 to 4F9/2
635
entangled networks did not show such π···π interactions,
which suggests that this interaction might play an important
role in the stabilization of the entangled networks synthesized
CN 5 displays a strong absorption band centered at 305 nm
in this work. Regarding CN
6, its photophysical properties
and two weak absorption bands at 230 nm and 330 nm (Fig.
10c and Table 3) that can be assigned to the IL transitions in
addition to seven narrow absorption bands that are attributed
to the f-f transitions of Er(III) as shown in Table 4.28
could not be studied because the crystals are unstable when
exposed to air.
The Er-based coordination compounds usually display an f-
f based luminescence with a weak intensity at 1530 nm in the
Acknowledgements
NIR region due to the spin-forbidden transition between the
fundamental 4I15/2 and the first excited state I13/2
This work was supported by the National Council for
Scientific and Technological Development (CNPq grant number
550572/2012-0 and research fellowships), the Brazilian Federal
Agency for Support and Evaluation of Graduate Education
(CAPES) and the Rio de Janeiro Research Foundation (FAPERJ).
We are grateful to the Material Characterization
4
.
28 Therefore,
the fluorescence spectrum of CN
measured in the solid state at room temperature upon
excitation at 305 nm. CN did not exhibit luminescence in the
5 in the NIR region was
5
NIR region most likely because of the quenching of the
vibronic coupling with the harmonics of the C-H and O-H
vibrations from the water, DMSO and ligand molecules. 29
(http://www.uff.br/lamate/),
Molecular
Spectroscopy
(http://www.uff.br/lame/), NMR (http://www.laremn.uff.br)
and X-ray Diffraction (http://www.ldrx.uff.br) Multiuser
Laboratories from Universidade Federal Fluminense. We also
thank Prof. Fabio Miranda for assistance with the
photophysical measurements.
Conclusions
Four new CNs have been synthesized using the rigid ligand
4,4'-ethynylenedibenzoate (edb2-) – [Co(edb)(H2O)(Py)2],
3
;
;
[Cd(edb)(DMSO)2]·0.5(DMSO), 4; [Er2(edb)3(DMSO)2(H2O)2],
5
Notes and references
and [Gd2(edb)3(H2O)4],
entanglements.
6 – with a variety of structures and
1
(a) R. S. Batten, N. R. Champness, X.-M. Chen, J. Garcia-
Martinez, S. Kitagawa, L. Öhrström, M. O’Keeffe, M. Suh and
J. Reedijk, Pure Appl. Chem., 2013, 85, 1715; (b) S. Kitagawa,
CN 3 is a 1D network in which the ligand coordinates to the
Co(II) in the bridging mode. The Co-based CN synthesized in
this work did not growth into other dimensions because the
pyridine and water molecules coordinated to Co(II) in the axial
and equatorial positions. After 15 minutes of exposure to air,
R. Kitaura and S.-I. Noro, Angew. Chem. Int. Ed., 2004, 43
,
2334; (c) S. L. James, Chem. Soc. Rev., 2003, 32, 276; (d) M.
Eddaoudi, D. Moler, H. Li, B. Chen, T. Reineke, M. O’Keeffe
and O. M. Yaghi, Acc. Chem. Res., 2001, 34, 319.
2
(a) S. Gao, C. G. Morris, Z. Lu, Y. Yan, H. G. W. Godfrey, C.
Murray, C. C. Tang, K. M. Thomas, S. Yang and M. Schöder,
Chem. Mater., 2016, 28, 2331; (b) B. Wang, X.-L. Lv, D. Feng,
L.-H. Xie, J. Zhang, M. Li, J.-R. Li and H.-C. Zhou, J. Am. Chem.
Soc., 2016, 138, 6204; (c) H. Zheng, Y. Zhang, L. Liu, W. Wan,
P. Guo, A. M. Nyström and X. Zou, J. Am. Chem. Soc., 2016,
138, 962; (d) M. W. Lohan, Y. A. Lau, Y. Zheng, E. A. Hall, M.
A. Hettinger, R. P. Marks, M. L. Hosler, F. M. Rossi, Y. Yuan
CN
properties could not be investigated.
CN is an inclined 3D polycatenated sql net formed by the
3 lost its crystallinity; therefore, its photophysical
4
square subunit Cd2(CO2)4(DMSO)4 linked through the 2-
connected edb2- unit. An interesting and unusual π···π
interaction between the triple bond of the ligand edb2-
appears to provide additional stabilization to the
and J. F. Uribe-Romo, Catal. Sci. Technol., 2016, 6, 5647; (e)
polycatenated structure. Upon excitation at
displayed a strong emission at λem = 444 nm (Φem = 0.057),
which is attributed to the IL charge-transfer due to the *–
λmax = 305 nm, CN
M. Yoon, R. Srirambalaji and K. Kim, Acc. Chem. Res., 2016,
49, 483; (f) J. S. F. Silva, G. F. Sa, M. N. Eberlin, C. M. Ronconi,
G. A. Bataglion, D. Lopez-Malo and S. Alves Jr., Plos One,
2015, 10, e0128436.
(a) A. A. Tehrani, A. Morsali and M. Kubicki, Dalton Trans.,
2015, 44, 5703; (b) M. Maekawa, T. Tominaga, K. Sugimoto,
T. Okubo, T. Kuroda–Sowa, M. Munakata and S. Kitagawa,
CrystEngComm., 2012, 14, 5955; (c) J. Duan, M. Higuchi, C.
Zou, W. Jin and S. Kitagawa, CrystEngComm., 2015, 17, 5609;
(d) L. Hashemi, A. Morsali and O. Büyükgüngor, New J.
Chem., 2014, 38, 3187; (e) S. Tripathi, R. Srirambalaji, S. Patra
4
π
π
transitions. An emission at λem = 586 nm indicates metal-
perturbed intraligand transitions (MPIL).
3
CN 5 is a rare 2D 5-connected cem network construct by an
Er2(CO2)6(DMSO)2 subunit linked through the ligand edb2-.
Despite the large void between the grids of the network,
entanglement is not observed, which is likely probably due to
14 | J. Name., 2012, 00, 1-3
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ARTICLE
and G. Anantharaman, CrystEngComm., 2015, 17, 8876. (f)
D.-S. Li, Y.-P. Wu, J. Zhao, J. Zhang, and J. Y. Lu, Coord. Chem.
Rev., 2014, 261, 1.
H.-L. Jiang, T. A. Makal and H.-C. Zhou, Coord. Chem. Rev.,
2013, 257, 2232.
363, 2616; (d) B. Murugesapandian and P. W. Roesky, Eur. J.
Inorg. Chem., 2011, 26, 4103; (e) N. G. Charles, E. A. H.
Griffith, P. F. Rodesiler and E. L. Amma, Inorg. Chem., 1983,
22, 2717; (f) F. Jian, H. Xiao, P. Sun and P. Zhao, Molecules,
4
5
6
2004, 9, 876; (g) H.-X. Chen, Y. Ma, F. Zhou, B. Wu, Q.-F. Xu,
S. R. Batten and R. Robson, Angew. Chem., Int. Ed., 1998, 37,
1460.
(a) L. Carlucci, G. Ciani and D. M. Proserpio, Coord. Chem.
J.-M. Lu and J.-F. Ge, J. Solid State Chem., 2013, 203, 1.
22 M. Chen, C. E. Sañudo, E. Jimenez, S.-M. Fang, C.-S. Liu and
M. Du, Inorg. Chem., 2014, 53, 6708.
Rev., 2003, 246, 247. (b) G.-W. Xu, Y.-P. Wu, H.-B. Wang, Y.- 23 (a) E. V. Alexandrov, V. A. Blatov and D. M. Proserpio, J.
N. Wang, D.-S. Li, and Y.-L. Liu, CrystEngComm, 2015, 17,
9055. (c) D.-S. Li, P. Zhang, J. Zhao, Z.-F. Fang, M. Du, K. Zou,
and Y.-Q. Mu, Cryst. Growth Des., 2012, 12, 1697. (d) D.-S. Li,
F. Fu, J. Zhao, Y.-P. Wu, M. Du, K. Zou, W.-W. Donga, and Y.-
Y. Wang, Dalton Trans., 2010, 39, 11522. (e) D.-S. Li, J. Zhao,
Struct. Chem., 2014, 55, 1308; (b) J. Zhang, Y.G. Yao, X. Bu,
Chem. Mater., 2007, 19, 5083; (c) D. L. Long, R. J. Hill, A. J.
Blake, N. R. Champness, P. Hubberstey, C. Wilson and M.
Schröder, Chem. Eur. J., 2005, 11, 1384; (d) L.-F. Ma, L.-Y.
Wang, Y.-Y. Wang, M. Du and J.-G. Wang, CrystEngComm.,
2009, 11, 109; (e) L. K. Sposato, J. A. Nettleman and R. L.
LaDuca, CrystEngComm., 2010, 12, 2374; (f) J. Li, Y. Peng, H.
Liang, Y. Yu, B. Xin, G. Li, Z. Shi and S. Feng, Eur. J. Inorg.
Chem., 2011, 17, 2712; (g) L.-Y. Xin, G.-Z. Liu, X.-L. Li and L.-Y.
Wang, Cryst. Growth Des., 2012, 12, 147; (h) L.-Y. Xin, G.-Z.
Liu and L.-Y. Wang, J. Solid State Chem., 2011, 184, 1387; (i)
Z.-H. Zhang, S.-C. Chen, Q. Chen, M.-Y. He and H. Xu, Inorg.
Chem. Commun., 2011, 14, 1819. (j) F.-L. Liang, D.-Y. Ma and
L. Quin; Acta Cryst. C, 2016, 72, 373. (k) N. Goel, Inorg. Chim.
Acta, 2016, 450, 330.
Y.-P. Wu, B. Liu, L. Bai, K. Zou, and M. Du, Inorg. Chem., 2013
52, 8091.
,
7
(a) L. Carlucci, G. Ciani and D. M. Proserpio. CrystEngComm.,
2003, , 269. (b) Y.-L. Liu, K.-F. Yue, D.-S. Li, Y. Yu, L. Houa,
5
and Y.Y. Wanga, CrystEngComm, 2013, 15, 2791.
L. Carlucci, G. Ciani, D. M. Proserpio, Tatiana G. Mitina, and
V. A. Blatov. Chem. Rev., 2014, 114, 7557.
8
9
J. H. Park, W. R. Lee, Y. Kim, H. J. Lee, D. W. Ryu, W. J. Phang
and C. S. Hong, Cryst. Growth Des., 2014, 14, 699.
10 (a) B. T. N. Pham, L. M. Lund and D. Song, Inorg. Chem.,
2008, 47, 6329; (b) A. D. Burrows, L. C. Fisher, D. Hodgson, 24 C. R. M. O. Matos, F. S. Miranda, J. W. d. M. Carneiro, C. B.
Pinheiro and C. M. Ronconi, Phys. Chem. Chem. Phys., 2013,
15, 13013.
M. F. Mahon, N. F. Cessford, T. Düren, C. Richardson and S. P.
Rigby, Inorg. Chem., 2012, 14, 188; (c) J. Bai, H.-L. Zhou, P.-Q.
Liao, W.-X. Zhang and X.-M. Chen, CrystEngComm., 2015, 17
4462; (d) T. Gadzikwa, B.-S. Zeng, J. T. Hupp and S. T.
Nguyen, Chem. Commun., 2008, 31 3672; (e) D. J.
Tranchemontagne, K. S. Park, H. Furukawa, J. Eckert, C. B.
,
25 T. M. Fasina, J. C. Collings, J. M. Burke, A. S. Batsanov, R. M.
Ward, D. Albesa-Jové, L. Porrès, A. Beeby, J. A. K. Howard, A.
J. Scott, W. Clegg, S. W. Watt, C. Viney and T. B. Marder, J.
Mater. Chem., 2005, 15, 690.
,
Knobler and O. M. Yaghi, J. Phys. Chem. C, 2012, 116, 13143. 26 S.-L. Zheng, J.-H. Yang, X.-L. Yu, X.-M. Chen and W.-T. Wong,
(f) R. J. Marshall, S. L. Griffin, C. Wilson and R. S. Forgan, J. Inorg. Chem., 2004, 43, 830.
Am. Chem. Soc., 2015, 137. (g) X.-L. Lv, M. Tong, H. Huang, B. 27 (a) L.-Y. Zhang, J.-P. Zhang, Y.-Y. Lin and X.-M. Chen, Cryst.
Wang, L. Gan, Q. Yang, C. Zhong and J.-R. Li, J. Solid State
Chem., 2015, 223, 104. (h) A. Dutta, A. G. Wong-Foy and A. J.
Matzger, Chem. Sci., 2014, 5, 3729.
Growth Des., 2006, 12, 1684. (b) J. Tao, M.-L. Tong, J.-X. Shi,
X.-M. Chen and S. W. Ng, Chem. Commun., 2000, 20, 2043.
28 R. C. Evans, P. Douglas and C. J. Winscom, Coord. Chem. Rev.,
2006, 250, 2093.
11 G. G. da Silva, C. S. Silva, R. T. Ribeiro, C. M. Ronconi, B. S.
Barros, J. L. Neves and S. Alves Jr. Synthetic Metals, 2016, 29 B. Chen and G. Qian, Metal-Organic Frameworks for
220, 369. Photonics Applications, Springer-Verlag, Berlin, 2013.
12 J. M. Duisenberg, L. M. J. Kroom-Batenburg and M. M. J. J. 30 (a) B. Li, H.-M. Wen, Y. Cui, G. Qian, B. Chen, Prog. Polym.
Schreurs, Appl. Cryst., 2003, 36, 220.
13 G. M. Sheldrick, Acta Cryst. A., 2008, 64, 112.
14 A. L. Spek, J. Appl. Cryst., 2003, 36, 7.
15 V. A. Blatov, A. P. Shevchenko and D. M. Proserpio, Cryst.
Growth Des., 2014, 14, 3576.
Sci., 2015, 48, 40. (b) P. Martín-Ramos, M. D. Miranda, M. R.
Silva, M. E. S. Eusebio, V. Lavín and J. Martín-Gil, Polyhedron,
2013, 65, 187; (c) P. Martín-Ramos, J. T. Coutinho, M. R.
Silva, L. C. J. Pereira, A. M. M. Beja and J. Martıín-Gil, J.
Chem. Crystallogr., 2014, 44, 255.
16 C. A. Téllez, E. Hollauer, M. A. Mondragon and V. M. Castaño, 31 K. Norton, G. A. Kumar, J. L. Dilks, T. J. Emge, R. E. Riman, M.
Spectrochim. Acta. A., 2001, 57, 993.
G. Brik and J. G. Brennan, Inorg. Chem., 2009, 48, 3573.
17 S. Demir, H. M. Çepni, N. Bilgin, M. Holynska and F. Yilmaz,
Polyhedron, 2016, 115, 236.
18 K. Nakamoto, Infrared and Raman spectra of inorganic and
coordination compounds. Part B: Applications in
coordination, organometallic, and bioinorganic chemistry,
John Wiley & Sons, New Jersey, 2009.
19 E. Prince, International Tables for Crystallography Volume C:
Mathematical, physical and chemical tables, Kluwer
Academic Publishers, Netherlands, 2004.
20 (a) W.-X. Yin, Y.-T. Liu, Y.-J. Ding, Q. Lin, X.-M. Lin, C.-L. Wu,
X.-D. Yao and Y.-P. Cai, CrystEngComm., 2015, 17, 3619; (b)
A. V. Kuttatheyil, M. Handke, J. Bergmann, D. Lässig, J.
Lincke, J. Haase, M. Bertmer and H. Krautscheid, Chem. Eur.
J., 2015, 21, 1118; (c) D. Liu and J.-P. Lang, CrystEngComm.,
2014, 21, 76.
21 (a) L. Liu, G.-M. Zhang, R.-G. Zhu, Y.-H. Liu, H.-M. Yao and Z.-
B. Han, RSC Adv., 2014,
Petrusenko, V. N. Kokozay, O. V. Shishkin and M. V. Zhigalko,
Inorg. Chem. Commun., 2003, , 896; (c) Z. Li, G. Mei, H.
4, 46639; (b) O. V. Pryma, S. R.
6
Zhang, G. Li, W. Wang and Z. Zhang, Inorg. Chim. Acta, 2010,
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