Tetranuclear Zn(II) and mononuclear Ni(II) based coordination polymers derived from a pair of isomeric 1,2,4-triazole ligands 3,5-disubstituted by pyridine and acetate ethyl ester groups

Article abstract of DOI:10.1016/j.poly.2015.12.047

A pair of isomeric compounds, namely L1-Et [2-(5-(pyridin-4-yl)-4H-1,2,4-triazol-3-yl)acetate ethyl ester] and L3-Et [2-(5-(pyridin-3-yl)-4H-1,2,4-triazol-3-yl)acetate ethyl ester], has been synthesized in this work, and they are used as multi-dentate ligands to react with certain transition-metal ions under solvothermal conditions. As a result, two three-dimensional (3D) coordination polymers, i.e. {[Zn(L1)(H₂O)]ClO₄·2H₂O·0.5MeOH}_n (C1) and {[Ni(L2)₂](ClO₄)₂·2H₂O}_n (C3), have been yielded and structurally characterized, where ligand L2 is found to be the decomposition product of ligand L3-Et. It is noted that a novel tetranuclear Zn₄(L1)₄ based cluster-organic framework is constructed in the case of C1 exhibiting a three-dimensional (3D) 2-fold interpenetrating diamond structure. By comparing the structures of C1 and C3, it is concluded that the competition between metal-ion complexation and ligand decomposition leads to the formation of different coordination polymers.

Full text of DOI:10.1016/j.poly.2015.12.047

Accepted Manuscript
Tetranuclear Zn(II) and mononuclear Ni(II) based coordination polymers de-
rived from a pair of isomeric 1,2,4-triazole ligands 3,5-disubstituted by pyridine
and acetate ethyl ester groups
Bin Hu, Yue-Hua Wang, Hui-Fen Qian, Yu-Xin Peng, Wei Huang
PII:
S0277-5387(15)00797-4
DOI:
http://dx.doi.org/10.1016/j.poly.2015.12.047
POLY 11746
Reference:
Polyhedron
To appear in:
Received Date:
Accepted Date:
5 October 2015
23 December 2015
Please cite this article as: B. Hu, Y-H. Wang, H-F. Qian, Y-X. Peng, W. Huang, Tetranuclear Zn(II) and mononuclear
Ni(II) based coordination polymers derived from a pair of isomeric 1,2,4-triazole ligands 3,5-disubstituted by
pyridine and acetate ethyl ester groups, Polyhedron (2015), doi: http://dx.doi.org/10.1016/j.poly.2015.12.047
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Tetranuclear Zn(II) and mononuclear Ni(II) based coordination
polymers derived from a pair of isomeric 1,2,4-triazole ligands
3,5-disubstituted by pyridine and acetate ethyl ester groups
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Bin Hu,a,b Yue-Hua Wang,a,c Hui-Fen Qian,a,* Yu-Xin Peng,c Wei Huangc,
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a College of Chemistry and Molecular Engineering, Nanjing Tech University,
Nanjing, Jiangsu Province, 210009, P. R. China
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b
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School of Environmental and Chemical Engineering, Nanchang Hangkong
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University, Nanchang, Jiangxi, 330063, P. R. China.
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State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of
Microstructures, School of Chemistry and Chemical Engineering, Nanjing University,
Nanjing 210093, P. R. China
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ABSTRACT
A
pair
of
isomeric
compounds,
ethyl
namely
ester] and
L1-Et
L3-Et
[2-(5-(pyridin-4-yl)-4H-1,2,4-triazol-3-yl)acetate
[2-(5-(pyridin-3-yl)-4H-1,2,4-triazol-3-yl)acetate ethyl ester], has been synthesized in
this work, and they are used as multi-dentate ligands to react with certain
transition-metal ions under solvothermal conditions. As
a
result, two
 Corresponding author. Tel.: +86-25-89686526; fax: +86-25-89682309
E-mail addresses: qhf@njtech.edu.cn (H.-F. Qian); whuang@nju.edu.cn (W. Huang).
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three-dimensional
(3D)
coordination
polymers,
i.e.
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{[Zn(L1)(H2O)]ClO4·2H2O·0.5MeOH}n (C1) and {[Ni(L2)2](ClO4)2·2H2O}n (C3),
have been yielded and structurally characterized, where ligand L2 is found to be the
decomposition product of ligand L3-Et. It is noted that a novel tetranuclear Zn4(L1)4
based cluster-organic framework is constructed in the case of C1 exhibiting a
three-dimensional (3D) 2-fold interpenetrating diamond structure. By comparing the
structures of C1 and C3, it is concluded that the competition between metal-ion
complexation and ligand decomposition leads to the formation of different
coordination polymers.
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Keywords: Structural isomer; Metal-organic framework; Ligand decomposition;
Zinc(II) complex; Nickel(II) complex
1. Introduction
The design and synthesis of metal-organic frameworks (MOFs) have received more
and more attention in the past two decades. Based on the concept of crystal
engineering, a variety of MOFs with intriguing structures and topologies have been
synthesized by joining metal-containing units with bridging organic linkers [1, 2].
Meanwhile, carboxylates and N-containing ligands are among the most important and
widely used candidates for constructing functional coordination complexes owing to
their fascinating characteristics, including functional materials in the areas of
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photoluminescence [3, 4], catalysis [5], recognition [6, 7], adsorption [8], separation
[9] and magnetism [10].
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Coordination complexes based on 1,2,4-triazole and its derivatives have been
extensively studied in recent years [11-15]. It has been known that 1,2,4-triazole
moiety in certain multi-functional ligands is relatively easy to exhibit several
coordination modes, especially under aggressive solvothermal conditions [11, 16-17],
where the competition between metal-ion complexation and ligand decomposition is
believed to play important roles during the self-assembled process. From the
viewpoint of ligand design, incorporation of diverse functional groups such as pyridyl,
triazole and carboxylic acid groups into one molecule is an emerging practical
strategy for constructing metal-organic frameworks with versatile topologies and
functionalities [18-21]. However, the use of these multi-functional ligands would
result in very complicated, where oxidation, reduction, hydrolyzation, ring-opening
and even decomposition of ligands took place in some cases. Thus, it is still very
challenging for preparing desired MOFs based upon well-defined multi-functional
ligands.
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In this work, a pair of isomeric ternary compounds having pyridyl, 1,2,4-triazole
and carboxyl groups simultaneously has been synthesized, namely L1-Et
[2-(5-(pyridin-4-yl)-4H-1,2,4-triazol-3-yl)acetate
ethyl
ester]
and
L3-Et
[2-(5-(pyridin-3-yl)-4H-1,2,4-triazol-3-yl)acetate ethyl ester]. They are used as
multi-dentate ligands to react with certain transition-metal ions under solvothermal
conditions, in order to provide some MOFs that have intriguing structures and
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topologies such as multinuclear cluster-organic frameworks with diverse architectures
and n-fold interpenetrated topologies. In this work, two 3D coordination polymers, i.e.
{[Zn(L1)(H2O)]ClO4·2H2O·0.5MeOH}n (C1) and {[Ni(L2)2](ClO4)2·2H2O}n (C3),
have been isolated and structurally characterized, where ligand L2 is found to be the
decomposition product of ligand L3-Et. It is noted that a novel cluster-organic
framework with tetranuclear Zn4(L1)4 unit is constructed in the case of C1 exhibiting
a 3D 2-fold interpenetrating diamond structure. By comparing the structures of C1
and C3, it is concluded that the competition between metal-ion complexation and
ligand decomposition leads to the formation of different coordination polymers.
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2. Experimental
2.1. Materials and measurements
All solvents and chemicals were of analytical grade and used without further
purification. Column chromatography was carried out on silica gel (300-400 mesh)
and analytical thin-layer chromatography (TLC) was performed on glass plates of
silica gel GF-254 with detection by UV. Standard techniques for synthesis were
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carried out under argon atmosphere. H and C NMR spectra were obtained using
CDCl3 as the deuterium solvent.
Elemental analyses (EA) were measured with a Perkin-Elmer 1400C analyser.
Infrared spectra (4000~400 cm-1) were recorded on a Nicolet FTIR 170X
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spectrophotometer. 1H and C NMR spectroscopic measurements were performed on
a Bruker AM-400 NMR spectrometer, using TMS (SiMe4) as an internal reference at
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room temperature. UV-visible (UV-vis) spectra were recorded with a Shimadzu
UV-3100 double-beam spectrophotometer using a quartz glass cell with a path length
of 10 mm at room temperature. Luminescence spectra were recorded on an F-4600
fluorescence spectrophotometer at room temperature (25 C). Electrospray ionization
mass spectra (ESI-MS) were recorded on a Finnigan MAT SSQ 710 mass
spectrometer in a scan range 200~1000 amu. Powder X-ray diffraction (PXRD)
measurements were performed on a Philips X′pert MPD Pro X-ray diffractometer
using Cu K radiation ( = 0.15418 nm), in which the X-ray tube was operated at 40
kV and 40 mA at room temperature.
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Caution! Although no problem was encountered in our experiments, transition
metal perchlorates are potentially explosive and should be carefully performed in
small quantities.
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2.2. Preparation of L1-Et and L3-Et
2-(5-(Pyridin-4-yl)-4H-1,2,4-triazol-3-yl)acetate
ethyl
ester
(L1-Et).
Isonicotinohydrazide (2.19 g, 16.0 mmol) was added into a solution of
malonomonoimidic acid diethyl ester hydrochloride (6.27 g, 32.0 mmol) in EtOH
(180 cm3). The reaction mixture was refluxed for 36 hours, and then cooled to room
temperature. The solvent was removed and the residue was washed with brine,
extracted thoroughly with ethyl acetate (EA) until no more products could be detected
by TLC, purified by column chromatography (silica gel, methanol/EA = 1:30), and
dried in vacuo. Light yellow solid was finally obtained in a yield of 0.73 g (39%).
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M.p., 124-126 °C. Anal. Calcd for C11H12N4O2: C, 56.89; H, 5.21; N, 24.12%. Found:
C, 56.98; H, 4.99; N, 24.24%. Main FT-IR absorptions (KBr pellets, cm-1): 3438 (bw),
1733 (vs), 1616 (vs), 1462 (w), 1425 (w), 1389 (w), 1369 (w), 1331 (w), 1300 (m),
1244 (w), 1209 (w), 1122 (w), 1029 (s), 939 (w), 837 (m), 750 (m)，718 (w), 685 (w),
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591 (w), 525 (w). H NMR (500 MHz, CDCl3): δ = 8.71 (d, J = 5.8 Hz, 2H,
pyridine-H), 7.98 (d, J = 6.0 Hz, 2H, pyridine-H), 4.30 (q, J = 7.1 Hz, 2H, CH2), 4.05
(s, 2H, CH2), 1.34 (t, J = 7.1 Hz, 3H, CH3). 13C NMR (400 MHz, CDCl3): δ = 169.1,
150.1, 138.3, 120.7, 62.1, 32.7, 14.1. UV-Vis (in methanol): λmax = 247 nm. Negative
ESI-MS in methanol (m/z): Calcd. for [C11H12N4O2] 232.10, found 231.08 [M-H]-.
2-(5-(Pyridin-3-yl)-4H-1,2,4-triazol-3-yl)acetate ethyl ester L3-Et. L3-Et was
prepared by a similar method to L1-Et except that nicotinohydrazide (1.10 g, 8.0
mmol) was used instead of isonicotinohydrazide. The desired compound L3-Et was
separated by silica gel column chromatography using EA as gradient eluent affording
white microcrystals in a yield of 1.05 g (56%). M.p., 73-75 °C. Anal. Calcd. for
C11H12N4O2: C, 56.89; H, 5.21; N, 24.12%. Found: C, 56.57; H, 4.91; N, 24.37%.
Main FT-IR absorptions (KBr, cm-1): 3464 (bw), 1738 (vs), 1605 (m), 1582 (m), 1481
(m), 1416 (m), 1373 (m), 1329 (m), 1267 (w), 1196 (vs), 1097 (w), 1209 (w), 1032
(m), 1014 (m), 962 (w), 885 (w), 829 (m), 723 (w), 708 (w), 654 (w), 621 (w), 571
(w). 1H NMR (400 MHz, CDCl3): δ = 9.28 (d, J = 1.6 Hz, 1H, pyridine-H), 8.79 (dd,
J = 4.9, 1.6 Hz, 1H, pyridine-H), 8.36 (dt, J = 8.0, 1.9 Hz, 1H, pyridine-H), 7.48 (ddd,
J = 8.0, 4.9, 0.7 Hz, 1H, pyridine-H), 4.27 (q, J = 7.1 Hz, 2H, CH2), 4.07 (s, 2H, CH2),
1.31 (t, J = 7.1 Hz, 3H, CH3). 13C NMR (125 MHz, CDCl3): δ = 166.1, 163.6, 160.9,
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152.6, 147.9, 134.2, 123.8, 120.2, 62.3, 32.0, 14.1. Negative ESI-MS in methanol
(m/z): Calcd. for [C11H12N4O2] 232.10, found 231.08 [M-H]-. UV-Vis (in methanol):
λmax = 244 nm. Colorless block single crystals of L3-Et suitable for X-ray
crystallographic analysis were obtained from methanol by slow evaporation in air at
room temperature for one week.
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2.3. Syntheses of metal complexes
Preparation of {[ZnL1(H2O)]ClO4·2H2O·0.5MeOH}n (C1). Ligand L1-Et (23.2 mg,
0.10 mmol) and Zn(ClO4)2·6H2O (37.2 mg, 0.10 mmol) were placed in a thick-walled
pyrex tube (ca. 26 cm long). After the addition of methanol (2.5 cm3) and H2O (0.5
cm3), the mixture was treated in the ultrasonator for one minute, frozen with liquid N2,
evacuated under a vacuum, and sealed with a torch. The tube was then placed inside
an oven at 90°C under the solvothermal reaction condition for 3 days to furnish the
pale yellow crystals in a yield of 31.5 mg (72%) based on ligand L1-Et. Anal. Calcd.
for [C19H30Cl2N8O19Zn2]: C, 26.04; H, 3.45; N, 12.79%. Found: C, 25.78; H, 3.69; N,
12.64%. Main FT-IR absorptions (KBr pellets, cm-1): 3456 (bw), 1615 (s), 1593 (vs),
1530 (w), 1492 (w), 1439 (m), 1421 (m), 1391 (m), 1264 (w), 1228 (w), 1121 (vs),
1026 (m), 991 (w), 943 (w), 846 (w), 808 (w), 744 (m), 703 (w), 627 (m), 572 (w),
530 (w). UV-Vis (in methanol): λmax = 260 nm. Fluorescence (solid): λmax, ex = 325 nm,
λmax, em = 405 nm. Colorless block crystals of known Zn(II) complex C2 [22] were
obtained as a by-product of this reaction in a low yield of 1.5 mg (5%).
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Preparation of {[Ni(L2)2](ClO4)2·2H2O}n (C3). The preparation of C3 follows the
same procedure as that of C1 by the treatment of a mixture of ligand L3-Et (27.8 mg,
0.10 mmol), Ni(ClO4)2·6H2O (36.6 mg, 0.1 mmol), methanol (2.5 cm3) and H2O (0.5
cm3). Purple single crystals suitable for X-ray diffraction were obtained under the
solvothermal reaction condition for 3 days in a yield of 13.3 mg (47%) based on
ligand L3-Et. Anal. Calcd. for C12H18Cl2N6NiO12: C: 25.38; H: 3.19; N: 14.80%.
Found: C: 25.56; H: 3.47; N: 14.71%. Main FT-IR absorptions (KBr, cm-1): 3520
(bw), 1649 (s), 1624 (m), 1580 (m), 1485 (w), 1431 (w), 1369 (w), 1204 (w), 1086
(vs), 901 (w), 837 (w), 725 (w), 623 (w). UV-Vis (in methanol): λmax = 262 nm.
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2.4. X-ray data collection and solution
Single-crystal samples of L3-Et, C1 and C3 were glue-covered and mounted on
glass fibers and then used for data collection at 291(2) K. The diffraction data were
collected on a Bruker SMART 1K CCD diffractometer using graphite
mono-chromated MoK radiation ( = 0.71073 Å). The crystal systems were
determined by laue symmetry and the space groups were assigned on the basis of
systematic absences using XPREP. Absorption corrections were performed to all data
and the structures were solved by direct methods and refined by full-matrix
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least-squares method on Fobs by using the SHELXTL-PC software package [23]. All
non-H atoms were anisotropically refined and all hydrogen atoms were inserted in the
calculated positions assigned fixed isotropic thermal parameters and allowed to ride
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on their respective parent atoms. The summary of the crystal data, experimental
details and refinement results for ligand L3-Et, complexes C1 and C3 is listed in
Table 1. Selected bond distances and bond angles are given in Table SI1, while
hydrogen bonding interactions are shown in Table SI2 (see supporting information).
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3. Results and discussion
3.1. Syntheses and spectral characterizations
Ligands L1-Et and L3-Et and their metal complexes C1 and C3 were prepared in
satisfactory yields, as displayed in Schemes 1 and 2, respectively. The peaks in 1H and
13C NMR spectra of L1-Et and L3-Et clearly manifest the formation of desired
heterocyclic aromatic compounds (Fig. SI1-2 in Supporting Information). This pair of
isomeric ligands has two rigid 1,2,4-triazole and pyridine rings as well as one flexible
carboxylic ester group, which could provide multiple coordination sites and
coordination modes in the process of metal-ion complexation. In this work, Zn(II) and
Ni(II) complexes C1, C2 and C3 were synthesized by the solvothermal method
because control experiments by using the general solution method revealed quick
precipitates and very complicated products. However, it is interesting to mention that
the competition between metal-ion complexation and ligand decomposition is
observed for ligands L1-Et and L3-Et in the presence of different metal ions.
Our results revealed that the control of reaction temperature and the use of solvent
are very important in the process of preparing complex C1. In our experiments,
complex C1 could only be obtained below 90 °C, where the ligand is the hydrolysate
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of L1-Et. In addition, a small amount of known complex C2 was obtained as a
by-product (5 %). However, when the temperature was higher than 90 °C, ligand
decomposition would be the main reaction and complex C2 was isolated in a high
yield (> 75 %). Furthermore, comparative experiments revealed that the mixture of
methanol and water was very important for producing complex C1 in addition to the
control of reaction temperature because other solvents such as ethanol, propyl alcohol,
butyl alcohol and their mixture with water would yield merely complex C2.
In contrast, when L3-Et was used to replace L1-Et for constructing some other
metal-organic frameworks, ligand decomposition of L3-Et took place again under the
same hydrothermal condition. As a result, a new 3D Ni(II) complex C3 with the
isonicotinohydrazide ligand was successfully obtained as purple single crystals and it
was structurally characterized. Nevertheless, analogous Ni(II) complex of C1 bearing
ligand L3-Et could not be isolated in our experiments whatever reaction conditions
were used, indicative of the difference in the nature of central metal ion. In addition,
blank experiments indicated that ligands L1-Et and L3-Et were stable under the same
solvothermal conditions in the absence of metal ions, where only the mixture of
isomeric ligands and corresponding hydrolyzed products can be detected after the
solvothermal reactions.
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UV-Vis absorption spectra of this pair of isomeric ligands (L1-Et and L3-Et) and
two metal coordination polymers (C1 and C3) in methanol are illustrated in Fig. 1.
Only a small hypsochromic shift of 3 nm is observed from L1-Et (247 nm) to L3-Et
(244 nm), which can be ascribed to the difference in their molecular structures. In
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contrast, after Zn(II) ion complexation, the maximum absorption peak is slightly
red-shifted to 250 nm. However, no obvious absorption peaks can be observed in the
case of complex C3 because of its very low solubility in methanol.
1
2
3
4
5
6
7
8
9
Furthermore, the solid-state fluorescence spectrum of Zn(II) complex C1 indicates
one intense fluorescence emission at 405 nm (λex= 325 nm) at room temperature (Fig.
SI3), which is different from two fluorescence inactive ligands L1-Et and L3-Et. It is
suggested that the fixation of coordination bonds by forming the Zn4(L1)4 cluster,
which could greatly increases the rigidity of the whole coordination polymer, is
responsible for the strong fluorescence emission of complex C1. In addition, the pure
phase of complexes C1 and C3 are also confirmed by PXRD patterns as shown in Fig.
SI4, where the simulated and as-synthesized curves are almost identical.
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3.2. Description of single-crystal structures of L3-Et, C1 and C3
The molecular structure of ligand L3-Et with the atom-numbering scheme is
shown in Fig. 2. It crystallizes in the monoclinic P21/c space group, where the
connected 1,2,4-triazole and pyridine rings are almost coplanar with the dihedral
angle of 6.1(4). In the crystal packing of ligand L3-Et, offset – stacking
interactions are found between adjacent 1,2,4-triazole and pyridine rings with the
centroid-centroid separations of 3.396(5) and 3.823(5) Å, respectively. In addition,
intermolecular C–H···N and C–H···O hydrogen bonding interactions are observed
between neighboring molecules (Table SI2). As a result, a two-dimensional (2D)
supramolecular network is formed with the assistance of – stacking and hydrogen
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bonding interactions.
1
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3
4
5
6
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8
9
Perspective view of the tetranuclear compound C1 is shown in Fig. 3. It
crystallizes in the tetragonal space group P42/n, where one Zn(II) ion, one ligand L1
-
(hydrolysate of L1-Et), one coordinated water molecule, one free ClO4 anions, half a
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methanol molecule and two solvent water molecules constitute the asymmetric unit.
The central Zn(II) ion is five-coordinated by three oxygen atoms (one water
molecule and two carboxylate oxygen atoms from different L1 ligands) with the
Zn–O bond lengths of 1.992(3) ~ 2.133(3) Å as well as two nitrogen atoms (one
pyridyl and one triazole from different L1 ligands) with the Zn–N distances of
2.066(4) and 2.016(3) Å. The coordination geometry of central Zn(II) ion can be
described as the distorted trigonal bipyramid, where the τ parameter is calculated to
be 0.72 [24]. Ligand L1 acts as a tridentate bridging ligand in C1, extending the
structure into an infinite 3D framework. It is noted that a novel Zn4(L1)4 cluster unit
is formed with neighboring Zn∙∙∙Zn distance of 4.897(3) Å, as can be seen in Fig. 4b.
In addition, the 3D framework is further stabilized by N–H···O and O–H···O
hydrogen bonding interactions as well as π-π stacking interactions between adjacent
L1 ligands with the centroid-to-centroid separation of 3.801(6) Å.
For a better insight into the unique architecture of C1, topological analysis has
been carried out by using TOPOS [25, 26]. Interpenetration is also found in
exploring the packing structure of C1, if the central Zn(II) ions are considered as
topological nodes. As demonstrated in Fig. 3c, every Zn(II) center can be regarded as
a 4-connected nod in this case. Therefore, complex C1 forms a unique uninodal
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(6,6)-connected net with a 3D 2-fold interpenetrating diamond structure, and the
point (Schlafli) symbol for the net is (66).
1
2
3
4
5
6
7
8
9
Complex C3 crystallizes in the orthorhombic space group Fdd2, and the
asymmetric unit contains one central Ni(II) ion, one dissociated ligand L2, one water
molecule and one perchlorate anion. As shown in Fig. 4a, the metal center in C3 is
six-coordinated by two pairs of nitrogen and oxygen atoms from hydrazide groups of
two ligands and two nitrogen atoms from another two pyridine rings, forming
distorted octahedron geometry. Ligand L2 serves as a bidentate bridging unit
connecting adjacent nickel(II) centers with the Ni∙∙∙Ni distance of 8.156(4) Å. In the
crystal structure of C3, equilateral hexagons containing the hexanuclear Ni units are
formed and they are extended to a 3D coordination polymer. No π–π stacking
interactions can be found between adjacent pyridine rings in the crystal packing of
C3.
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4. Conclusion
In summary, the competition between metal-ion complexation and ligand
decomposition has been observed for a pair of isomeric 1,2,4-triazole compounds
3,5-disubstituted by pyridine and acetate ethyl ester groups (L1-Et and L3-Et). Two
3D
coordination
polymers
C1
and
C3,
formulated
as
{[Zn(L1)(H2O)]ClO4·2H2O·0.5MeOH}n and {[Ni(L2)2](ClO4)2·2H2O}n), have been
yielded and structurally characterized, where ligand L2 is found to be the
decomposition product of ligand L3-Et. It is found that C1 exhibits a novel
13

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tetranuclear Zn4(L1)4 based cluster-organic framework with a 2-fold interpenetrating
diamond structure.
1
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8
9
Appendix A. Supplementary data
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CCDC 1428471-1428473 contains the supplementary crystallographic data for ligand
L3-ET, complexes C1 and C3. These data can be obtained free of charge via
http://www.ccdc.cam.ac.uk/conts/retrieving.html,
or
from
the
Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44)
1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk. Tables of selected bond lengths,
1
bond angles and Hydrogen bonding interactions for related crystal structures, H and
13C NMR spectra for ligands L1-Et and L3-Et, fluorescence and Powder X-ray
diffraction spectra for metal complexes are attached for this paper, together with the
CIF of Zn(II) complex C2. Supplementary data to this article can be found online at
http://dx.doi.org/.
Acknowledgements. This work was financially supported by the National Natural
Science Foundation of China (No. 21501088), the Natural Science Foundation of
Jiangxi Province (20151BAB213002) and the Education Department of Jiangxi
Province (N0. DB201302155).
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16

Table 1. Crystal data and structural refinements for compounds L3-Et, C1 and C3.
1
2
3
4
5
6
7
8
9
Compound
Empirical formula
Formula weight
T (K)
Crystal system
Space group
a / Å
L3-Et
C11H12N4O2
232.25
291(2)
monoclinic
P21/c
6.017(2)
23.777(9)
8.961(4)
90
C1
C3
C19H30Cl2N8O19Zn2 C12H18Cl2N6NiO12
876.19
291(2)
tetragonal
P42/n
18.1111(7)
18.1111(7)
11.2507(9)
90
567.93
291(2)
orthorhombic
Fdd2
21.969(2)
22.463(2)
8.7866(8)
90
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
b / Å
c / Å
 (o)
β (o)
115.647(5)
90
1155.6(8)
90
90
3690.4(4)
90
90
 (o)
V / Å3
4336.1(7)
0.10 x 0.12 x 0.12
8
1.740
1.215
Crystal size / mm
Z
0.12 x 0.11 x 0.10 0.12 x 0.10 x 0.10
4
4
Dc / Mg·m-3
 (Mo/K) /mm-1
F(000)
1.335
1.577
0.096
1.527
488
1784
2320
Absorption correction
Data collected / unique
Limiting indices
multi-scan
5594 / 2017
-7 h  7
-12  k  28
-10  l  10
multi-scan
18131 / 3242
-20 h  21
-20  k  21
-8  l  13
0.8623 / 0.8380
3242 / 240
R1 = 0.0532,
wR2 = 0.1450
R1 = 0.0708,
wR2 = 0.1555
1.030
multi-scan
5293 / 1884
-26 h  22
-25  k  26
-10  l  10
0.8680 / 0.8882
1884 / 150
R1 = 0.0367,
wR2 = 0.0998
R1 = 0.0394,
wR2 = 0.1030
1.099
Min. / max. transmission 0.9886 / 0.9905
Data / parameters
R1, wR2 (I > 2 (I))
2017 / 155
R1 = 0.0723
wR2 = 0.2104
R1 = 0.1259,
wR2 = 0.2399
0.937
R1, wR2 (all data)
Goodness of fit on F2
/e·Å-3 (max, min)
0.335 / -0.412
0.885 / -0.416
0.561 / -0.467
R1 = FoFcFo, wR2 = [[w(Fo2Fc2)2]w(Fo2)2]1/2
17

Schemes and Figures with captions
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Scheme 1. Schematic illustration for the preparation of compounds L1-Et, C1 and
C2.
Scheme 2. Schematic illustration for the preparation of compounds L3-Et and C3.
18

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Fig. 1. UV/Vis spectra of ligands L1-Et and L3-Et as well as complexes C1 and C3
in methanol at room temperature.
Fig. 2. (a) ORTEP drawing of ligand L3-Et with the atom-numbering scheme.
Displacement ellipsoids are drawn at the 30% probability level and the
hydrogen atoms omitted for clarity; (b) Perspective view of the π-π stacking
19

interactions in the crystal packing.
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Fig. 3.
(a) ORTEP drawing of zinc(II) complex C1 with the atom-numbering
scheme. Displacement ellipsoids are drawn at the 30% probability level
and the hydrogen atoms omitted for clarity; (b) Perspective view of C1
network with the π-π stacking interactions along c-axis; (c) Representation
of two interpenetrating uninodal (6,6)-connected net with an diamond-like
structure.
20

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Fig. 4.
(a) ORTEP drawing of nickel(II) complex C3 with the atom-numbering
scheme. Displacement ellipsoids are drawn at the 30% probability level
and the hydrogen atoms omitted for clarity; (b) Perspective view of the 3D
network in the crystal packing of C3.
21

Graphical Abstract - Pictogram
Tetranuclear Zn(II) and mononuclear Ni(II) based coordination
polymers derived from a pair of isomeric 1,2,4-triazole ligands
3,5-disubstituted by pyridine and acetate ethyl ester groups
Bin Hu, Yue-Hua Wang, Hui-Fen Qian, Yu-Xin Peng, Wei Huang
1

Graphical Abstract - Synopsis
Competition between metal-ion complexation and ligand decomposition has been
observed for a pair of isomeric compounds having pyridyl, 1,2,4-triazole and carboxyl
groups simultaneously, where a tetranuclear Zn4(L1)4 based 3D cluster-organic
framework C1 and a hexanuclear Ni(II) based 3D coordination polymer C3 have been
yielded, respectively.
1