Syntheses, structures and photoluminescent properties of Zn(∥)/Co(∥) coordination polymers based on flexible tetracarboxylate ligand of 5,5′-(butane-1,4-diyl)-bis(oxy)-di isophthalic acid

Article abstract of DOI:10.1016/j.jssc.2016.05.023

Three new mixed-ligand metal-organic frameworks based on 5,5′-(butane-1,4- diyl)-bis(oxy)-diisophthalic acid and transitional metal cations with the help of two ancillary bridging N-donor pyridyl and imidazole linkers, [Zn(L)_0.5(4,4′-bpy)]·2(H<

Full text of DOI:10.1016/j.jssc.2016.05.023

Journal of Solid State Chemistry 240 (2016) 82–90
Contents lists available at ScienceDirect
Journal of Solid State Chemistry
journal homepage: www.elsevier.com/locate/jssc
Syntheses, structures and photoluminescent properties of Zn(Ⅱ)/Co(Ⅱ)
coordination polymers based on flexible tetracarboxylate ligand of
5,5′-(butane-1,4-diyl)-bis(oxy)-di isophthalic acid
Yan-Peng Gao a,b,c, Le Guo b,c, Wei Dong a, Min Jia a, Jing-Xue Zhang a, Zhong Sun a,
Fei Chang a,
n
a Inner Mongolia Key Lab Chem & Phys Rare Earth Mat, College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, PR China
b Department of Chemistry and Chemical Engineering, Ordos College of Inner Mongolia University, Ordos 017000, PR China
c Department of Chemistry and Chemical Engineering, Ordos Applied Technology College, Ordos 017000, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Three new mixed-ligand metal-organic frameworks based on 5,5′-(butane-1,4- diyl)-bis(oxy)-dii-
sophthalic acid and transitional metal cations with the help of two ancillary bridging N-donor pyridyl
and imidazole linkers, [Zn(L)0.5(4,4′-bpy)] ꢀ 2(H2O) (1), [M(L)0.5(bib)] ꢀ 4(H2O) (M ¼ Zn (2), Co (3)), (4,4′-
bpy¼4,4′–bipyridine, bib¼1,4-bis (1H-imidazol-1-yl)-butane), have been synthesized under solvother-
mal conditions. Their structures and properties were determined by single-crystal and powder X-ray
diffraction analyses, IR spectra, elemental analyses and thermogravimetric analyses (TGA). Compounds
1–3 display a 3D 3-fold interpenetrated frameworks linked by the L4ꢁ ligands, ancillary N-donor linkers
and the free water molecules in the crystal lattice. Topological analysis reveals that 1–3 are a (4,4)-
connected bbf topology net with the (64 ꢀ 82)(66) topology. The effects of the L4ꢁ anions, the N-donor
ligands, and the metal ions on the structures of the coordination polymers have been discussed. Fur-
thermore, luminescence properties and thermogravimetric properties of these compounds were in-
vestigated.
Received 20 January 2016
Received in revised form
18 May 2016
Accepted 21 May 2016
Available online 21 May 2016
Keywords:
Multicarboxylate acid
Coordination polymers
Crystal structure
Fluorescence
& 2016 Elsevier Inc. All rights reserved.
1. Introduction
functional organic groups [24–26]. The flexibility of the organic
flexible multicarboxylate ligands provide the constructed func-
In recent years, the metal-organic frameworks (MOFs) has at-
tracted considerable attention not only for their intriguing archi-
tectures [1,2] and bewitching topological nets [3,4], but also for
their potential applications in gas storage substances [5,6], lumi-
nescent materials [7–9], magnetism substances [10–12], catalysis
[13,14], nonlinear optics [15–17] and so on. The current research in
the fields of MOFs has promoted the design of a target structure
with specific properties and functions [18,19]. Therefore, the in-
vestigation of the relationship between the topological structure
and the conformation of ligands is a challenging task for chemists
working on creating fascinating inorganic function compounds,
and it is necessary to research some properties of the resulting
coordination polymers.
tional MOFs tunable structures, which further have affected the
properties [27–30]. Moreover, when the ancillary ligands are in-
troduced to build the frameworks, the final structures have greater
tunability [31–33]. The ancillary bridging imidazole or pyridine
linkers holding different lengths and flexibilities have great effects
on the final architectures and topology as well as coordination
modes and molecular conformations of multicarboxylate acids
[34–36]. Therefore, preparing novel functional MOFs using such
kinds of flexible multicarboxylate and ancillary bridging imidazole
or pyridine linkers should be attempted. In this article, we have
chosen the flexible multicarboxylic acid, namely, 5,5′-(butane-1,4-
diyl)-bis(oxy)-diisophthalic acid (H4L), and two ancillary bridging
imidazole or pyridine linkers, namely, 4,4-bipyridine (4,4′-bpy)
[37–40] and 1,4-bis (1H-imidazol-1-yl)-butane (bib) [41–43].
Herein, three 3D 3-fold interpenetrated frameworks were ob-
tained through a mix ligand strategy under similar solvothermal
reactions, [Zn(L)0.5(4,4′-bpy)] ꢀ 2(H2O) (1), [M (L)0.5(bib)] ꢀ 4(H2O)
(M ¼ Zn (2), Co (3)) (Fig. S1, S2). Moreover, the syntheses, crystal
structures, topologies, thermal stabilities and photoluminescent
Recently, flexible multi-carboxylate ligands with two or more
aromatic rings were used to build interesting coordination fra-
meworks [20–23], especially some flexible frameworks with
n
Corresponding author.
E-mail address: ndchfei@imu.edu.cn (F. Chang).
http://dx.doi.org/10.1016/j.jssc.2016.05.023
0022-4596/& 2016 Elsevier Inc. All rights reserved.

Y.-P. Gao et al. / Journal of Solid State Chemistry 240 (2016) 82–90
83
properties are reported in this paper.
2.2.2. Synthesis of [Zn(L)0.5(4,4′-bpy)] ꢀ 2(H2O) (1)
A solution of Zn(NO3)2
ꢀ
(H2O)6 (0.0145 g, 0.05 mmol) in CH3OH
(0.5 mL) and a solution of 4,4′-bpy (0.0096 g, 0.05 mmol) in
CH3OH (0.5 mL)were added with stirring to a solution of H4L
(0.0104 g, 0.025 mmol) in DMF (1 mL), then 2 mL H2O was added
to this mixture solution. After the mixture solution was stirred for
20 min, 2 drops of 1 mol/L HNO3 solution was added to this re-
action solution, and then the reaction mixture solution were stir-
red for another 20 min. The colorless solution had been obtained
and then sealed in a 5 mL sealing glass vessel. The vessel was
heated to 80 °C and held at that temperature for 48 h, then slowly
cooling to room temperature, block crystals of 1 for single crystal
X-ray diffraction were obtained by filtration and dried at air.
yield:80%. Anal. Caled.(%): C 52.09, H 4.08, N 6.02. Found (%): C
52.62, H 4.17, N 5.94. EDX El. AN. (wt%): Zn 11.41, O 26.07, C 54.95,
N 7.57. (at%): Zn 2.52, O 23.55, C 66.12, N 7.81. FT-IR (KBr, cmꢁ1):
3455(s), 3101(w), 2951(w), 2907(w), 2870(w), 1615(s), 1570(s),
1491(m), 1453(m), 1411(s), 1377(s), 1351(s), 1317(m), 1259(m), 1221
(m), 1121(m), 1070(m), 1048(s), 923(w), 874(w), 816(s), 777(s), 731
(s), 638(m), 543(w), 469(w).
2. Experimental section
2.1. Materials and general methods
The ligands H4L and bib were prepared according to the lit-
erature [44–47]. Other chemicals were obtained from commercial
sources and used without further purification, such as K2CO3 (A.R.,
Z99% ), Zn(NO3)2
ꢀ
6H2O (A.R., Z99%) Co(NO3)2 6H2O (A. R.,
ꢀ
Z99%) NaOH (A.R., Z99%), 4,4′-bpy (A.R., Z99%), CH3OH (A.R.,
Z99%), 5-hydroxy-isophthalic acid diethyl ester (A.R., Z98%), 1,4-
dichlorobutane (A.R., Z98%), and so on. Fourier Transform Infra-
red Spectra (FT-IR) were measured on Nexus-670FT spectrum in-
strument at the range of 4000–400 cmꢁ1 using KBr pellets.
Compounds 1–3 were examined by and TEM (FEI Tecnai G2 F20
200 kV) (Fig. S6), and compounds 1 and 2 were examined by SEM
(Hitachi S4800 SEM and Bruker QUANTAX 200 EDX) at accelerat-
ing voltage up to 10 KV (Fig. S7). The Elemental analyses of C, H,
and N were carried out on a Perkin-Elmer 2400 CHNS elemental
2.2.3. Synthesis of [M (L)0.5(bib)] ꢀ 4(H2O) (M ¼ Zn (2), Co (3))
The synthesis of compound 2 and 3 was similar to that of
compound 1 except that 4,4′-bpy (0.0096 g, 0.05 mmol) was re-
analyzer. Thermogravimetric analyses were performed on
a
STA409pc thermogravimetric analyzer from 30 to 700 °C at a
heating rate 10 °C minꢁ1 under air atmosphere. Powder X-ray
diffractometer (PXRD) was performed on a X’Pert PRO (PW3071/
placed by bib (0.0095 g, 0.05 mmol) for 2 and 3, and Zn(NO3)2
ꢀ
(H2O)6 (0.0145 g, 0.05 mmol) was replaced by Co(NO3)2 (H2O)6
ꢀ
xx Bracket) diffractometer with Cu K
α
radiation (
λ¼1.5406 Å).
(0.0145 g, 0.05 mmol) for 3. For compound 2, Anal. Caled. (%): C:
47.23, H: 5.25, N:11.01. Found(%): C: 47.42, H: 5.12, N: 11.08. EDX El.
AN. (wt%): Zn 9.59, O 23.89, C 52.56, N 13.96. (at%): Zn 2.09, O
21.29, C 62.40, N 14.21. FT-IR (KBr, cmꢁ1): 3469(s), 3131(m), 2949
(m), 2872 (m), 1667(m), 1621(s), 1575(s), 1529(m), 1451(m), 1404
(s), 1375(s), 1346(s), 1261(m), 1237(m), 1098(s), 1052(s), 952(m),
923(w), 843(w),803(m), 729(m), 657(m), 627(w), 551(w), 426(w).
For compound 3, Anal. Caled. (%): C: 47.11, H: 5.32, N:11.11. Found
(%): C: 47.40, H: 5.06, N: 11.09. FT-IR (KBr, cmꢁ1): 3428(s), 3130
(m), 2949(m), 2872 (w), 1667(w), 1617(m), 1560(s), 1453(m), 1408
(m), 1376(s), 1351(s), 1262(m), 1235(m), 1097(s), 1052(s), 950(m),
923(w), 840(w), 806(m), 781(m), 730(m), 659(m), 627(w), 543(w).
UV–vis spectra were measured on a TU-1901 UV–vis spectro-
photometer in the solid state at room temperature. Solid-state
photoluminescent spectra were measured on an Edinburgh
FLS920 fluorescence spectrometer at room temperature Scheme 1.
2.2. Synthesis
2.2.1. Synthesis of 5,5′-(butane-1,4-diyl)-bis(oxy)-diisophthalic acid
(H4L)
5-hydroxy-isophthalic acid diethyl ester (2.38 g, 10 mmol) and
anhydrous K2CO3 (3 g, 22 mmol) were put in a 50 mL round bot-
tom flask under nitrogen atmosphere and treated with 20 mL of
dry DMF. The reaction mixture was stirred for 1 h at 70 °C followed
by addition of 1,4-dichlorobutane (0.64 g, 5 mmol), and the re-
sulting mixture was stirred for 20 h in an oil-bath at 80 °C. At the
end of the period, the solution was allowed to cool to room tem-
perature and then poured into ice-water (100 mL) with vigorous
stirring that afforded a white precipitated (tetraethyl 5,5′-(butane-
1,4-diyl)-bis(oxy)-diisophthalate) which was collected by filtra-
tion, washed with water three times, and dried in air. Then the
tetraethyl 5,5′-(butane-1,4-diyl)-bis(oxy) diisophthalate (2.65 g,
5 mmol) was hydrolyzed by refluxing it with 95% ethanol solution
for 1 h followed by addition of NaOH (0.8 g, 20 mmol) and the
reaction mixture was refluxed for 15 h in an oil-bath. Finally, the
resulting solution was poured into ice-water (100 mL) with vig-
orous stirring and was acidified carefully with 4 M HCl to obtain a
white precipitate. After keeping it overnight in the freezer, the
white solid was collected by filtration and dried at air. Yield: 2.02 g
(96%). FT-IR (KBr, cmꢁ1): 3096.35(s), 2961(s), 1697(s), 1597(m),
1462(m), 1402(m), 1273(m), 1126(w), 1051(m), 909(w), 759(w),
668(w), 530(w), 479(w).
3. X-ray crystallography
Single-crystal X-ray data for compound 1–3 were collected on
an Bruker Smart Apex
monochromated Mo K
Ⅱ
CCD diffractometer using graphite
α
radiation (
λ
¼1.71073 Å) at room tem-
perature. Empirical absorption correction was applied. The struc-
tures were solved by direct methods and refined by the full-matrix
least-squares methods on F2 using the SHELXTL-97 software [48].
All non-hydrogen atoms were refined anisotropically. All of the
hydrogen atoms were placed in the calculated positions. Pertinent
crystallographic data collection and parameters are collated in
Table 1. Selected bond lengths and angles are collated in Table S1.
Topological analyses of the compounds were performed by using
the TOPOS software [49]. CCDC-1444200, CCDC-1471013 and
CCDC-1444201 contain the supplementary crystallographic data
for compound 1, 2 and 3, respectively. These data can be obtained
free of charge from the Cambridge crystallographic data centre via
Scheme 1. Synthesis of 5,5′-(butane-1,4-diyl)-bis(oxy)diisophthalic acid (H4L).

84
Y.-P. Gao et al. / Journal of Solid State Chemistry 240 (2016) 82–90
Table 1
Crystal data and structure refinement for compound 1–3.
Compound
1
2
3
Empirical formula
Formula weight
C20H15N2O7Zn
460.71
C20H21N4O9Zn
526.78
C20H21CoN4O9
520.34
T (K)
293(2)
293(2)
293(2)
Crystal system
space group
Monoclinic
P21/c
Monoclinic
P21/c
Monoclinic
P21/c
a (Å)
b (Å)
c (Å)
α (°)
7.4085(10)
15.002(2)
17.9311(19)
90
8.045(4)
17.549(8)
18.014(7)
90
8.0319(8)
17.9407(19)
17.9318(17)
90
β (°)
107.583(5)
90
1899.8(4)
4
1.611
1.340
108.093(18)
90
2417.5(19)
4
1.447
1.071
108.644(4)
90
2448.3(4)
4
1.412
0.755
γ (°)
V (Å3)
Z
Calculated density (Mg/m3)
M (mmꢁ1
)
F(000)
940
1084
1072
θ range for data collection(°)
Reflections collected / unique
R(int)
1.81–28.39
13765/4737
0.0302
1.66–27.64
15532/5567
0.0611
3.18–28.42
64579/6081
0.0358
Data / restraints / parameters
Goodness-of-fit on F2
R1, wR2 [I42s(I)]a
4737/0/261
1.046
0.0715, 0.2147
0.0910, 0.2298
5567/0/307
1.045
0.0820, 0.2289
0.1035, 0.2466
6081/4/307
1.067
0.0903, 0.2549
0.1077, 0.2806
R1, wR2 (all data)
a
R1¼Σ||Fo|-|Fc||/Σ|Fo|, wR2¼Σ[w(Fo2-Fc2)2]/Σ[w(Fo2)2]1/2
.
www.ccdc.cam.ac.uk/data_request/cif.
two pyridyl rings is 13.022°. Therefore, two pyridyl rings of 4,4′-bpy
are not coplanar. On the other hand each L4ꢁ ligand connects to four
1
0
[ZnN2O2] tetrahedrons at four orientational positions by a μ1
monodentate modes forming a 2D network, characterized by the
phenyl-O…O-Cphenyl torsion angle of 180° in the central part of the
L4ꢁ ligand, and the torsion angle of Cphenyl-O…CH2-CH2,
-η
:
η
4. Result and discussion
C
4.1. Synthesis and general characterization
O-CH2…CH2-CH2,
CH2-CH2…CH2-CH2,
CH2-CH2…CH2-O,
and
All crystallization of compounds 1–3 were synthesized under
similar reaction conditions by solvothermal methods, by changing
metal ions and solvent, the single crystals suitable for the single-
crystal X-ray diffraction analysis were finally obtained. For com-
pounds 1–3, the measured PXRD patterns closely match the si-
mulated patterns generated from the results of Single-Crystal
Diffraction data, indicating pure phases of 1–3 products (Figs. 5–7).
The IR spectra of H4L and compound 1–3 also show characteristic
the asymmetric and symmetric stretching vibrations of the car-
boxylate groups are observed in the ranges of 1597–1621 and
1346–1402 cmꢁ1, respectively [50,51] (Fig. S3).
CH2-CH2… O-Cphenyl is 178°, 179°, 180°, 179°, and 178° in the L4ꢁ li-
gand, and the dihedral angle between two phenyl rings of L4ꢁ is 0°,
hence all oxygen and carbon atoms of the L4ꢁare mainly coplanar
(Fig. 1(c)). Finally, the 2D network structures formed by L4ꢁ ligand
and [ZnN2O2] tetrahedra were interconnected by the 1D metal-pyr-
idyl chains to form
a
3D framework with channels
(15.0977 Å ꢂ 22.2255 Å) (Fig. 2(a)). The 3D grid allows each frame-
works to be penetrated by two other independent frameworks to
form the interesting 3-fold interpenetrating 3D frameworks, with
isolated water molecules occupying the neutral channels (Fig. 2(b)).
A better insight into the nature of compound 1 can be provided
by a topology analysis. The extension of the structure of 1 into a
(4,4)-connected bbf topology net [52–54] is accomplished by
binding two L4ꢁ ligands and two bib ligands to the four-connected
Zn (Ⅱ) nodes. The L4ꢁ ligands can be simplified as a four-connected
node, the bib ligands are taken as linkers, and the 3D structure can
be simplified as a 4-connected net with the Schläfli symbol of
(64 ꢀ 82)(66) (Fig. 2(c)). The topological analysis of 1 reveals that the
individual 3D framework has spacious space, it allows another two
identical 3D frameworks to interpenetrate it in a normal mode
giving a 3-fold interpenetrated 3D to 3D frameworks (Fig. 2(d)).
4.2. Structure descriptions
4.2.1. Description of crystal structure of compound 1
Single-crystal X-ray structure determination of compound 1
reveals a 3-fold interpenetrated three-dimensional (3D) frame-
work that crystallizes in the monoclinic space group P21/c. The
relevant asymmetric unit consists of one crystallographically in-
dependent Zn(Ⅱ) ion in a distorted tetrahedral geometry, a half of
coordinated L4ꢁ ligand, one coordinated 4,4′-bpy and two lattice
water molecules. The coordination geometry around the Zn(Ⅱ)
metal ion is found to be distorted tetrahedral.
4.3. Description of crystal structure of compound 2 and 3
The tetrahedral [ZnN2O2] geometry around the Zn(Ⅱ) metal ion is
comprised of two oxygen atoms from two different L4ꢁ ligand units,
and two nitrogen atoms from two different 4,4′-bpy ligands (Fig. 1(a)).
The bond distances of Zn-O and Zn-N are in the range 1.952–2.079 Å
and the bond angles around the Zn (Ⅱ) centre are in the range 95.38–
132.51°. In the compound 1, on the one hand the 4,4′-bpy ligand
connects two tetrahedral [ZnN2O2] centres in the 1D metal-pyridyl
chains through the N atoms of the pyridyl rings with a separation of
10.9588 Å resulting in the formation of a V-shaped chain as shown in
Fig. 1(b). In the 1D metal-pyridyl chain, the dihedral angle between
When the auxiliary ligand was changed from rigid 4,4′-bpy to
flexible bib used in the preparation for 2 and 3. The results of
Single-crystal X-ray structure determination show that the struc-
ture of compound 2 are similar to that of compound 3, so we
describe the structure of the compound 3 as an example, com-
pound 3 with a 3D framework crystallizes in the monoclinic space
group P21/c. The asymmetric unit contains one independent Co(Ⅱ)
ion, a half of coordinated L4ꢁ ligand, one coordinated bib and four
lattice water molecules. As shown in Fig. 3(a), the Co (Ⅱ) metal ion

Y.-P. Gao et al. / Journal of Solid State Chemistry 240 (2016) 82–90
85
Fig. 1. (a) Molecular diagram representing the coordination environment around the Zn(Ⅱ) metal ions in 1. (b) 1D V-shaped metal-pyridyl chain formed by tetrahedral
[ZnN2O2] geometry and 4,4′-bpy in 1. (c) The 2D network structure formed by L4ꢁ ligands and [ZnN2O2] tetrahedra.
1
0
is four-coordinated by two oxygen atoms from two different L4ꢁ
ligand units, and two nitrogen atoms from two bib ligands re-
spectively. The bond distances of Co-O and Co-N are in the range
1.963–2.024 Å and the bond angles around the Co (Ⅱ) centre are in
the range 97.56–124.01°. In the compound 3, the N-donor imida-
zolyl ligand bib occurs in one kind of coordination mode.
four Co atoms at four angles in a μ1
-η
:
η
monodentate modes and
connects the [CoN2O2] tetrahedra in a 2D network conformation,
characterized by the Cphenyl-O…O-Cphenyl torsion angle of 180° in the
central part of the L4ꢁ ligand and the dihedral angle between two
phenyl rings is 0°, but the torsion angle of Cphenyl-O…CH2-CH2,
O-CH2…CH2-CH2,
CH2-CH2…CH2-CH2,
CH2-CH2…CH2-O,
and
The bib ligand connects two tetrahedral [CoN2O2] centres in the
1D metal-imidazolyl chains through the N atoms of the imidazolyl
rings, creating a separation of 13.61 Å to form a V-shaped chain as
shown in Fig. 3(b). In the 1D structure, the flexible bib exhibits anti–
gauche–anti conformation and the dihedral angle between two imi-
dazolyl rings is 62.015°. In compound 3, each L4ꢁ ligand connects to
CH2-CH2…O-Cphenyl is 157.94°, 83.55°, 180°, 83.55°, and 157.94°, re-
spectively. The two phenyl rings of L4ꢁ is coplanar, but a great
changes have taken place in the -(CH2)4- of L4ꢁ ligand (Fig. 3(c)). In
this compound, the 2D network structure formed by L4ꢁ ligand and
[CoN2O2] tetrahedra was linked by the 1D metal-imidazolyl chains to
form a 3D framework with channels (18.1567 Å ꢂ 24.0957 Å) (Fig. 4

86
Y.-P. Gao et al. / Journal of Solid State Chemistry 240 (2016) 82–90
Fig. 2. (a) 3D frameworks of 1 formed by L4ꢁ ligand, [ZnN2O2] tetrahedra and 4,4′-bpy. (b) 3-fold interpenetrating 3D frameworks of 1. (c) the individual 3D topos structure
of 1 with the Schläfli symbol of (64 ꢀ 82)(66). (d) the 3D 3-fold interpenetrated topos structure for 1.
(a)). Longer length of co-ligand (bib) in compound 2 and 3 than that
of co-ligand (bpy) in compound 1 resulted in that compound 2 and 3
exhibit larger channels of individual 3D frameworks in size
(18.1567 Å ꢂ 24.0957 Å) than those (15.0977 Å ꢂ 22.2255 Å) of com-
pound 1. Correspondingly, compound 2 and 3 with larger channels
size accommodate more H2O molecules than compound 1. The 3D
grid allows each frameworks to be penetrated by two other in-
dependent frameworks to form the interesting 3D 3-fold inter-
penetrating frameworks with isolated water molecules occupying the
neutral channels (Fig. 4(b), S5).
From the view of topology, by treating the Co (Ⅱ) atoms and the
L4ꢁ ligands as a four-connected node, the bib ligands are taken as
linkers, the 3D single framework can be simplified as a (4,4)-con-
nected bbf topology net, like compound 1, with the Schläfli symbol of
(64 ꢀ 82)(66) (Fig. 4(c)). The topological analysis of 3 reveals that the 3D
individual framework have spacious space, it allows another two
identical 3D single frameworks to interpenetrate it in a normal mode
giving a 3-fold interpenetrated 3D to 3D framework (Fig. 4(d)).
gravity (DTG) for the H4L and the crystalline samples of com-
pounds 1–3 were recorded under air atmosphere in the tem-
perature range of 30–700 °C (Fig. 8, S8). The TGA curves of all three
compounds have released the lattice water before 350 °C, reflect-
ing the fact that the lattice water in the framework is unstable and
easy to separate from framework at low temperatures. The first
weight losses corresponding to the release of water molecules are
observed before 365 °C for compound 1 (observed 9.12%, calcu-
lated 7.83%), 323 °C for compound 2 (observed 11.36%, calculated
13.69%), 325 °C for compound 3 (observed 16.34%, calculated
13.84%). The anhydrous compositions begin to decompose at
365 °C and ending above 490 °C for 1, at 323 °C and ending above
497 °C for 2, and at 325 °C and ending above 417 °C for 3, due to
the decomposition of the organic part of the framework. The re-
maining weight may correspond to the formation of ZnO for
compound 1 (observed 18.14%, calculated 17.72%) and compound 2
(observed 20.12%, calculated 15.39%), CoO for compound 3 (ob-
served 15.63%, calculated 14.42%).
4.4. PXRD studies and thermogravimetric analyses
4.5. UV–vis absorption spectra of compound 1-3
The simulated of single X-ray diffraction data and experimental
PXRD patterns of compounds 1–3 obtained at room temperature
are shown in (Figs. 5–7). Rietveld full-profile fitting results based
on the structural parameters of compounds 1–3 indicate the po-
sitions of the major diffraction peaks are in agreement with those
calculated single crystal data (Figs. S9–S11). The difference in-
tensities between simulated and experimental patterns may be
due to the variation in preferred orientation of crystalline powder
samples during collection of the experimental XRD data.
The UV–vis spectra of compound 1–3 together with the free H4L
ligand in the solid state at room temperature were measured. The
Kubelka-Munk functions [55–57] converted from the diffuse re-
flectance data were plotted in Fig. 9. The H4L exhibits strong absorption
with a maximum at 316 nm in the range of 280ꢁ352 nm, which
probably corresponds to the
π-π
* and n- * transitions centered on the
π
benzene ring. The absorption of 4,4′-bpy is strong in a similar range
with one peak at 290 nm [58,59]. Compared to the free H4L ligand,
compound 1–3 exhibit absorption with maxima at 307 nm, 308 nm,
305 nm, respectively, and the absorption peaks of compounds 1, 2, and
Thermogravimetric analyses (TGA) and Differential thermal

Y.-P. Gao et al. / Journal of Solid State Chemistry 240 (2016) 82–90
87
Fig. 3. (a) Molecular diagram representing the coordination environment around the Co (Ⅱ) metal ions in 3. (b) 1D V-shaped metal-imidazoly chain formed by tetrahedral
[CoN2O2] geometry and bib in 3. (c) The 2D network structure formed by L4ꢁ ligand and [CoN2O2] tetrahedra.
3 have slightly blue-shifted in the same range. In compound 1, the
absorption peak is more stronger than other compound at 280 nm,
which may be attributed to the effect of 4,4′-bpy. In compound 3, the
characteristic absorption bands of UV–vis spectra around 580 nm are
correlated with the d-d transitions of tetrahedral coordinated Co2þ
[60–63].
based luminescent MOFs. The d10 metal ions not only have various
coordination numbers and geometries, but also display luminescent
properties with functional ligands [64,65]. The photoluminescence
properties of compound 1 and 2 together with the free H4L ligand, were
investigated in the solid state at room temperature (Table 2) and de-
picted in Fig. 10, S4. The photoluminescent spectra of the free ligands
show the main peak at 412 nm (λex¼339 ) for H4L, 466 nm (λex
¼390 nm) for 4,4′-bpy [66], 436 nm (λex ¼380 nm) for bib [67–69],
4.6. Photoluminescence properties
respectively, which may be caused by the
π
*-
π
and *-n transition. The
π
The metal-organic frameworks are promising candidates for ap-
plicable photoluminescent materials such as chemical sensors, light
emitting diodes, electro-chemical sensors and so on. Although a lot of
transition metal ions and rare-earth ions have been used to construct
MOFs, the Zn-based MOFs are the most interested transition metal
emission spectra for bands were observed at 452 nm (λex ¼337 nm) for
1, 401 and 418 nm (λex ¼348 nm) for 2. As the literature reported, the
d10 configured Zn(Ⅱ) cations are electrochemically inert, therefore,
when coordinated by ligands, they cannot take an electron from the
ligand with their 3d-orbitals, nor donate an electron to the ligand [36].

88
Y.-P. Gao et al. / Journal of Solid State Chemistry 240 (2016) 82–90
Fig. 4. (a) 3D framework of 3 formed by L4ꢁ ligand, [CoN2O2] tetrahedra and bib. (b) 3-fold interpenetrating 3D framework for 3. (c) the 3D single topos structure of 3 with
the Schläfli symbol of (64 ꢀ 82)(66). (d) the 3D 3-fold interpenetrated topos structure for 3.
Fig. 6. As-synthesized and simulated X-ray diffraction patterns of compound 2.
Fig. 5. As-synthesized and simulated X-ray diffraction patterns of compound 1.
In comparison to the free ligands, the emission maxima of 1 is red-
shifted by 40 nm as compared to free H4L ligand, and close to the free
4,4′-bpy ligand, inferring their emission bands may be assigned to the
intra-ligand charge transfer (ILCT), neither metal-to-ligand charge
transfer (MLCT) nor ligand-to-metal charge transfer (LMCT) happened.
The emission peaks of 2 are close to free H4L ligand, so the emission
bands of 2 can probably be attributed to the intra-ligand charge transfer
(ILCT). Experimental results show that compound 3 is non-emissive
under similar conditions, indicating the emissions of organic ligands
may be quenched completely in the compound, which may be due to
the emission quencher of Co (Ⅱ) in the structure. In term of the struc-
tures and emission spectra of compound 1 and 2, it is inferred that
different ligands co-ligands may be an important factor on influencing
different luminescent properties of compounds [36].

Y.-P. Gao et al. / Journal of Solid State Chemistry 240 (2016) 82–90
89
Table 2
wavelengths of the emission maxima and excitation (nm) of 1, 2, and organic li-
gands at room temperature.
Ligand /compound
λ
ex/nm
λem/nm
H4L
4,4′-bpy
bib
1
2
339
390
380
337
348
412
466
436
452
418, 401
Fig. 7. As-synthesized and simulated X-ray diffraction patterns of compound 3.
Fig. 10. Solid-state emission spectra at room temperature for the free H4L and 1, 2
(slit width ¼0.5 nm).
ancillary imidazole linkers 1,4-bis (1H-imidazol-1-yl)-butane (bib) for
2 and 3. These compounds display interesting and versatile co-
ordination features from 3D to 3D parallel entangled frameworks.
Topological analysis reveals that 1–3 are 3D (4,4)-connected bbf to-
pology net with the (64 ꢀ 82)(66) topology. The adjustable channels
size of individual 3D framework is realized by using different lengths
of co-ligands from byp to bib with keeping similar architectures of
compounds 1–3. In compound 3, the assignment of characteristic
absorption bands of UV–vis spectra at 580 nm correlated with the d-d
transitions of Co2þ ions in field of tetrahedral coordination is con-
firmed by the result of the single-crystal X-ray structure analysis. The
solid-state photoluminescent properties of 1 and 2 were investigated,
and the emission bands were assigned to the intra-ligand charge
transfer (ILCT), and the different emission wavelength due to the ef-
fect of co-ligands. The solid-state thermal stabilities were investigated.
The frameworks of 1, 2 and 3 are stable under 350 °C.
Fig. 8. Thermogravimetric curves of the H4L and the compounds 1–3.
Acknowledgements
We are grateful to the National Natural Science Foundation of
China (No. 20561003), Natural Science Foundation of Inner Mon-
golia (2004-08020202), Innovation Foundation for Students of
Ordos College of Inner Mongolia University (20140401).
Fig. 9. UV–vis spectrogram of compounds 1, 2, 3, and free H4L ligand in the solid
state.
5. Conclusions
Appendix A. Supporting information
In summary, we successfully designed and synthesized three co-
ordination polymers based on flexible multicarboxylic acid 5,5′-(bu-
tane-1,4-diyl)-bis(oxy)-diisophthalic acid (H4L), and one rigid ancillary
bridging pyridine linkers 4,4′ -bipyridine (4,4′-bpy) for 1, one flexible
Supplementary data associated with this article can be found in
the online version at http://dx.doi.org/10.1016/j.jssc.2016.05.023.

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Y.-P. Gao et al. / Journal of Solid State Chemistry 240 (2016) 82–90
References
[34] Z.-P. Deng, Z.-Y. Zhang, L.-H. Huo, S.W. Ng, H. Zhao, S. Gao, CrystEngComm 14
(2012) 6548.
[35] W.-Q. Kan, J.-F. Ma, B. Liu, J. Yang, CrystEngComm 14 (2012) 286–299.
[36] W.-Q. Kan, J.-F. Ma, Y.-Y. Liu, J. Yang, CrystEngComm 14 (2012) 2316.
[37] P.R. Matthes, J. Eyley, J.H. Klein, A. Kuzmanoski, C. Lambert, C. Feldmann,
K. Muller-Buschbaum, Eur. J. Inorg. Chem. (2015) 826–836.
[38] S. Parshamoni, S. Sanda, H.S. Jena, K. Tomar, S. Konar, Cryst. Growth Des., 2014.
[39] M. Tsotsalas, J.X. Liu, B. Tettmann, S. Grosjean, A. Shahnas, Z.B. Wang,
C. Azucena, M. Addicoat, T. Heine, J. Lahann, J. Overhage, S. Brase, H. Gliemann,
C. Woll, J. Am. Chem. Soc. 136 (2014) 8–11.
[40] H. Jia, M. Guo, B. Ma, Y. Liu, G. Li, Synthesis and Reactivity in Inorganic Metal-
Organic and Nano-Metal Chemistry, 43, 2013, pp. 1458–1464.
[41] J.-X. Yang, Y.-Y. Qin, J.-K. Cheng, Y.-G. Yao, Cryst. Growth Des. 14 (2014)
1047–1056.
[1] H.M. He, F.X. Sun, N. Zhao, R.R. Yuan, G.S. ZHu, RSC Adv. 4 (2014) 21535–21540.
[2] X. Yuan, X. Zhang, H. Zhao, L. Liu, B. Wu, Cryst. Growth Des. 13 (2013)
4859–4867.
[3] G.L. Wen, M.L. Han, F.W. Wang, X. Zhao, C.Y. Yin, Z. Anorg. Allg. Chem. 639
(2013) 2307–2311.
[4] H. Yang, H.-X. Zhang, D.-C. Hou, T.-H. Li, J. Zhang, CrystEngComm 14 (2012)
8684–8688.
[5] X.M. Zhang, J.J. Hou, C.H. Guo, C.F. Li, Inorg. Chem. 54 (2015) 554–559.
[6] G. Calleja, C. Martos, G. Orcajo, J.A. Botas, J.A. Villajos, CrystEngComm 17 (2015)
338–343.
[7] Y.L. Wu, G.P. Yang, Y.Q. Zhao, W.P. Wu, B. Liu, Y.Y. Wang, Dalton Trans. 44
(2015) 3271–3277.
[8] D. Banerjee, Z. Hu, J. Li, Dalton Trans. 43 (2014) 10668–10685.
[9] D. Banerjee, Z.C. Hu, S. Pramanik, X. Zhang, H. Wang, J. Li, CrystEngComm 15
(2013) 9745–9750.
[10] A. Ablet, D. Wang, W. Cao, L.C. Li, X.J. Zheng, Inorg. Chem. Commun. 52 (2015)
20–22.
[11] Y.X. Liu, D. Liu, C. Wang, J. Solid State Chem. 223 (2015) 84–94.
[12] P. Manna, B.K. Tripuramallu, S. Bommakanti, S.K. Das, Dalton Trans. 44 (2015)
2852–2864.
[13] W.L. Liu, N.S. Yang, Y.T. Chen, S. Lirio, C.Y. Wu, C.H. Lin, H.Y. Huang, Chem. Eur. J.
21 (2015) 115–119.
[14] D.D. Zu, L. Lu, X.Q. Liu, D.Y. Zhang, L.B. Sun, J. Phys. Chem. C 118 (2014)
19910–19917.
[15] C. Wang, D. Liu, W. Lin, J. Am. Chem. Soc. 135 (2013) 13222–13234.
[16] Y.P. He, Y.X. Tan, J. Zhang, Inorg. Chem. 52 (2013) 12758–12762.
[17] C. Wang, D.M. Liu, W.B. Lin, J. Am. Chem. Soc. 135 (2013) 13222–13234.
[18] P. Ramaswamy, N.E. Wong, G.K.H. Shimizu, Chem. Soc. Rev. 43 (2014)
5913–5932.
[19] R.L. Martin, M. Haranczyk, Cryst. Growth Des. 13 (2013) 4208–4212.
[20] H.B. Xu, S.H. Zhou, L.L. Xiao, H.H. Wang, S.Z. Li, Q.H. Yuan, J. Mater. Chem. C 3
(2015) 291–297.
[21] X.Y. Dong, R. Wang, J.Z. Wang, S.Q. Zang, T.C.W. Mak, J. Mater. Chem. A 3 (2015)
641–647.
[22] Y. Rachuri, K.K. Bisht, B. Parmar, E. Suresh, J. Solid State Chem. 223 (2015)
23–31.
[23] M.J. Dong, M. Zhao, S. Ou, C. Zou, C.D. Wu, Angew. Chem., Int. Ed. 53 (2014)
1575–1579.
[24] X. Feng, X.-L. Ling, L. Liu, H.-L. Song, L.-Y. Wang, S.-W. Ng, B.Y. Su, Dalton Trans.
42 (2013) 10292–10303.
[42] Z.Q. Shi, Y.Z. Li, Z.J. Guo, H.G. Zheng, CrystEngComm 16 (2014) 900–909.
[43] C. Zhang, H. Hao, Z. Shi, H. Zheng, CrystEngComm 16 (2014) 5662–5671.
[44] Z. Xue, T. Sheng, Y. Wang, S. Hu, Y. Wen, Y. Wang, H. Li, R. Fu, X. Wu, Crys-
tEngComm 17 (2015) 2004–2012.
[45] B. Xu, Q. Chen, H.-M. Hu, R. An, X. Wang, G. Xue, Cryst. Growth Des. 15 (2015)
2318–2329.
[46] Y.F. Xiao, T.T. Wang, H.P. Zeng, J. Solid State Chem. 221 (2015) 37–48.
[47] C.C. Wang, H.P. Jing, P. Wang, S.J. Gao, J. Mol. Struct. 1080 (2015) 44–51.
[48] G.M. Sheldrick, SHELXTL-97 Program for Crystal Structure olution and Re-
finement University of Gottingen, Germany, 1997.
[49] V.A. Blatov, Struct. Chem. 23 (2012) 955–963.
[50] A.V. Raghu, H.M. Jeong, J. Appl. Polym. Sci. 107 (2008) 3401–3407.
[51] D.P. Suhas, H.M. Jeong, T.M. Aminabhavi, A.V. Raghu, Polym. Eng. Sci. 54 (2014)
24–32.
[52] X. He, X.-P. Lu, Z.-F. Ju, C.-J. Li, Q.-K. Zhang, M.-X. Li, CrystEngComm 15 (2013)
2731–2744.
[53] J.-S. Hu, X.-Q. Yao, M.-D. Zhang, L. Qin, Y.-Z. Li, Z.-J. Guo, H.-G. Zheng, Z.-L. Xue,
Cryst. Growth Des. 12 (2012) 3426–3435.
[54] J.S. Hu, X.Q. Yao, M.D. Zhang, L. Qin, Y.Z. Li, Z.J. Guo, H.G. Zheng, Z.L. Xue, Cryst.
Growth Des. 12 (2012) 3426–3435.
[55] H. Lin, P. Liu, J. Zhang, X. Wang, G. Liu, J. Coord. Chem. 66 (2013) 612–623.
[56] Q.-L. Lu, J. Luan, X.-L. Wang, H.-Y. Lin, C. Xu, Transit. Met. Chem. (Lond.) 37
(2012) 713–719.
[57] Y.J. Liu, X.L. Lin, G.Y. Liu, J. Ying, A.X. Tian, J. Inorg. Organomet. Polym. Mater. 22
(2012) 946–951.
[58] Y. Gong, J. Li, J. Qin, J. Lin, CrystEngComm 14 (2012) 5862–5869.
[59] Y. Gong, T. Wu, J. Lin, B. Wang, CrystEngComm 14 (2012) 5649–5656.
[60] S.A. Laurence Poul, Noureddine Jouini, Fernand Fievet, Francoise Villain, Solid
State Sci. 3 (2001) 31–42.
[25] L. Li, B.B. Guo, G. Li, Inorg. Chem. Commun. 35 (2013) 351–354.
[26] B.B. Guo, L. Li, Y. Wang, Y.Y. Zhu, G. Li, Dalton Trans. 42 (2013) 14268–14280.
[27] M. Chen, Z.W. Wang, H. Zhao, C.S. Liu, Inorg. Chem. Commun. 45 (2014) 84–88.
[28] S.-J. Liu, Y.-F. Zeng, X. Hu, L. Xue, S.-D. Han, J.-M. Jia, T.-L. Hu, J. Solid State
Chem. 204 (2013) 197–204.
[29] M. Hassan, E. Haque, K.R. Reddy, A.I. Minett, J. Chen, V.G. Gomes, Nanoscale 6
(2014) 11988–11994.
[30] M. Hassan, K.R. Reddy, E. Haque, S.N. Faisal, S. Ghasemi, A.I. Minett, V.
G. Gomes, Compos. Sci. Technol. 98 (2014) 1–8.
[31] J.J. Wang, X.Y. Hou, L.J. Gao, M.L. Zhang, Y.X. Ren, F. Fu, Chin. J. Inorg. Chem. 30
(2014) 1616–1620.
[32] S.-N. Zhao, S.-Q. Su, X.-Z. Song, M. Zhu, Z.-M. Hao, X. Meng, S.-Y. Song, H.-
J. Zhang, Cryst. Growth Des. 13 (2013) 2756–2765.
[33] L. Fan, X. Zhang, Z. Sun, W. Zhang, Y. Ding, W. Fan, L. Sun, X. Zhao, H. Lei, Cryst.
Growth Des. 13 (2013) 2462–2475.
[61] P. Cossee, A.E.V. Arkel, J. Phys. Chem., Solids Pergamon Press, 15, 1960, pp 1–6.
́
[62] I. Balti, A. Mezni, A. Dakhlaoui-Omrani, P. Leone, B. Viana, O. Brinza, L.-S. Smiri,
N. Jouini, J. Phys. Chem. C 115 (2011) 15758–15766.
[63] Y. Brik, M. Kacimi, M. Ziyad, F. Bozon-Verduraz, J. Catal. 202 (2001) 118–128.
[64] C. Yan, Y.Z. Fan, L. Chen, M. Pan, L.Y. Zhang, J.J. Jiang, C.Y. Su, CrystEngComm 17
(2015) 546–552.
[65] Q.-G. Zhai, R.-R. Zeng, S.-N. Li, Y.-C. Jiang, M.-C. Hu, CrystEngComm 15 (2013)
965–976.
[66] J.S. Lucas, J.W. Uebler, R.L. LaDuca, CrystEngComm 15 (2013) 860–866.
[67] S.J. Li, K. Li, B.T. Qu, W. Zheng, Chin. J. Struct. Chem. 33 (2014) 193–198.
[68] H.J. Cheng, M. Yu, H.X. Li, C.N. Lu, D.X. Li, M.M. Chen, Z.G. Ren, J.P. Lang, J.
Coord. Chem. 66 (2013) 2335–2350.
[69] J.-Q. Liu, Y.-Y. Wang, T. Wu, J. Wu, CrystEngComm 14 (2012) 2906–2913.