Supramolecular assembly of a series of new coordination polymers based on 4,4′-(carbonylimino)dibenzoic acid: Syntheses, structures and photoluminescence investigation

Article abstract of DOI:10.1016/j.poly.2013.03.029

Assembly reactions of acylamide-containing dicarboxylate ligand 4,4′-(carbonylimino)dibenzoic acid (H₂L) with corresponding divalent metal ions resulted in the formation of seven new coordination polymers, namely Cd(L)(H₂O) (1), Zn(L)(H₂O) (2), Zn ₅(L)₂(OH)₆ (3), [Ni(L)(H₂O) ₂]·H₂O (4), [Cd(L)(py)(H₂O)] ·(DMF)·(C₆H₅Cl) (5), [Cd(L)(py) ₂]·2CH₃OH (6) and [Mn (HL)₂(py) ₂]·2DMF (7). In complex 1, the double chains composed Cd ^II and L^2- are connected by interlayer Cd-O bonds to form a three-dimensional architecture. Complex 2 exhibits a three-dimensional supramolecular architecture extended by hydrogen bonds involving O-Ha?[;?O and N-Ha?]?O types. Complex 3 displays a three-dimensional framework consisting of zinc-hydroxide layers and L ^2- pillars. Complex 4 is also a supramolecular three-dimensional network generated from linkage of Ni-O chains via versatile hydrogen bonds. Complex 5 exhibits an interdigitated network in which the cavities are occupied by guest DMF and C₆H₅Cl molecules. In complex 6, two-dimensional square-grid network was generated by linkage of Cd₂ units with L^2- ligands. Mono-depronated ligand presents in complex 7. The adjacent [Mn(py)(HL)] chains are arranged parallel to each other by forming hydrogen bonding between the acylamide groups and guest DMF molecules. The stability properties of 2, 3, 4, 6 and 7 have been presented. In addition, photoluminescence properties of complexes 2, 3, 5 and 6 are investigated.

Full text of DOI:10.1016/j.poly.2013.03.029

Polyhedron 55 (2013) 249–258
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Polyhedron
journal homepage: www.elsevier.com/locate/poly
Supramolecular assembly of a series of new coordination polymers
based on 4,40-(carbonylimino)dibenzoic acid: Syntheses, structures
and photoluminescence investigation
Juan-Juan Han a,1, Yan-Fei Niu a,1, Jie Han b, Xiao-Li Zhao a,
⇑
a Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University,
3663 North Zhongshan Road, Shanghai 200062, PR China
b School of Science & Technology, The Open University of Hong Kong, Kowloon, Hong Kong Special Administrative Region
a r t i c l e i n f o
a b s t r a c t
Assembly reactions of acylamide-containing dicarboxylate ligand 4,40-(carbonylimino)dibenzoic acid
(H2L) with corresponding divalent metal ions resulted in the formation of seven new coordination poly-
mers, namely Cd(L)(H2O) (1), Zn(L)(H2O) (2), Zn5(L)2(OH)6 (3), [Ni(L)(H2O)2]ꢀH2O (4), [Cd(L)(py)(H2-
O)]ꢀ(DMF)ꢀ(C6H5Cl) (5), [Cd(L)(py)2]ꢀ2CH3OH (6) and [Mn (HL)2(py)2]ꢀ2DMF (7). In complex 1, the
double chains composed CdII and L2ꢁ are connected by interlayer Cd–O bonds to form a three-dimen-
sional architecture. Complex 2 exhibits a three-dimensional supramolecular architecture extended by
hydrogen bonds involving O–Hꢀ ꢀ ꢀO and N–Hꢀ ꢀ ꢀO types. Complex 3 displays a three-dimensional frame-
work consisting of zinc-hydroxide layers and L2ꢁ pillars. Complex 4 is also a supramolecular three-
dimensional network generated from linkage of Ni–O chains via versatile hydrogen bonds. Complex 5
exhibits an interdigitated network in which the cavities are occupied by guest DMF and C6H5Cl mole-
cules. In complex 6, two-dimensional square-grid network was generated by linkage of Cd2 units with
L2ꢁ ligands. Mono-depronated ligand presents in complex 7. The adjacent [Mn(py)(HL)] chains are
arranged parallel to each other by forming hydrogen bonding between the acylamide groups and guest
DMF molecules. The stability properties of 2, 3, 4, 6 and 7 have been presented. In addition, photolumi-
nescence properties of complexes 2, 3, 5 and 6 are investigated.
Article history:
Received 21 August 2012
Accepted 13 March 2013
Available online 21 March 2013
Keywords:
Coordination polymers
Hydrogen bond
4,40-(Carbonylimino)dibenzoic acid
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
functionalized with acylamide unit: 4,40-(carbonylimino)dibenzoic
acid (H2L). There are multiple reasons for exploring H2L: (1) It con-
The exploration of coordination bond in the construction of
coordination polymers (CP) has resulted in a wide range of mul-
ti-dimensional solid-state architectures [1]. Applications includ-
ing heterogeneous catalysis, photochemistry, magnetism, gas
storage and separation based on coordination polymers have been
well documented [2]. In a parallel development, the highly direc-
tains two carboxylate groups, therefore, versatile coordination
modes could be adopted in the formation of new complexes with
fascinating properties [5]; (2) the presence of an acylamide group,
–CONH, may be expected to have a particularly potent as struc-
ture-determining unit in the formation of hydrogen bonds among
themselves and/or interacting with the guest molecules incorpo-
rated into the coordination architectures, which might turn out
to be significant structure-controlling factors [6]. In addition, the
relatively free rotatable capability of C–N bond of acylamide group
and C–C bond between phenyl ring and carboxylate group make
this ligand a flexible skeleton. In this article, we present the isola-
tion and structural characterization of seven new coordination
polymers: Cd(L)(H2O) (1), Zn(L)(H2O) (2), Zn5(L)2(OH)6 (3),
[Ni(L)(H2O)2]ꢀH2O (4), [Cd(L)(py)2(H2O)]ꢀ(DMF)ꢀ(C6H5Cl) (5),
[Cd(L)(py)2]ꢀ2CH3OH (6) and [Mn(HL)2(py)2]ꢀ2DMF (7) (py = pyri-
dine, DMF = dimethylformamide, C6H5Cl = chlorobenzene). The
crystallographic data of 1–7 are summarized in Table 1. In addi-
tion, thermal stability and luminescent properties of the new com-
plexes were also investigated.
tional bonds such as hydrogen bonding and p–p stacking are fre-
quently used as cohesive forces in the crystal engineering [3]. The
combination of coordination bonds, hydrogen bonding and/or
other weak interactions has been recognized as a very powerful
and versatile strategy in supramolecular assembly and material
chemistry [4].
Our conceived strategy in the present study is to investigate the
assembly of coordination polymers based on bicarboxylate ligand
⇑
Corresponding author. Tel./Fax: +86 21 62233179.
E-mail address: xlzhao@chem.ecnu.edu.cn (X.-L. Zhao).
These authors contributed equally to this work.
1
0277-5387/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2013.03.029

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J.-J. Han et al. / Polyhedron 55 (2013) 249–258
Table 1
Crystal data and structure refinement for complexes 1–7.
Complex
1
2
3
4
5
6
7
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C
15H11NO6Cd
C15H11NO6Zn
366.62
monoclinic
Pc
C15H12NO8Zn2.5
497.68
monoclinic
C2/c
34.634(2)
5.5604(4)
16.399(1)
90
100.453(2)
90
C15H15NO8Ni
395.99
monoclinic
Cc
C34H33ClN4O7Cd
757.49
monoclinic
C2/c
34.952(1)
6.1056(2)
33.918(1)
90
114.634(1)
90
C26H25N3O7Cd
603.89
monoclinic
P21/c
12.9342(4)
20.3616(6)
10.5043(3)
90
112.552(1)
90
C23H22N3O6Mn0.5
463.91
413.65
monoclinic
P21/c
16.0892(4)
11.7307(3)
7.2224(2)
90
97.841(1)
90
triclinic
ꢀ
P1
14.6567(8)
5.4421(3)
8.7148 (5)
90
93.383(1)
90
693.91(7)
2
1.755
6.9058(8)
35.957(4)
6.0158(7)
90
95.749(4)
90
1486.2(3)
4
1.770
8.5227(3)
8.6792(4)
15.6198(6)
99.603(1)
105.233(1)
96.321(1)
1084.70(8)
2
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
1350.39(6)
4
2.035
3105.7(4)
8
2.116
6579.3(4)
8
1.529
2554.9(1)
4
1.570
Z
qcalc (mg cmꢁ3
)
1.420
0.376
l
(mmꢁ1
)
1.651
1.803
3.892
1.354
0.800
0.905
F(000)
816
372
1960
816
3088
1224
481
h (°)
Rint
3.09–25.01
0.0182
1.39–25.50
0.0218
2.39–25.01
0.0396
2.27–25.00
0.0308
1.32–25.01
0.0258
1.70–25.01
0.0240
1.38–25.00
0.0207
Final R indices
[I > 2 (I)]
R indices (all data) R1 = 0.0172,
wR2 = 0.0409
R1 = 0.0163,
wR2 = 0.0404
R1 = 0.0339,
wR2 = 0.0892
R1 = 0.0341,
wR2 = 0.0895
R1 = 0.0503,
wR2 = 0.1296
R1 = 0.0619,
wR2 = 0.1422
R1 = 0.0329,
wR2 = 0.0850
R1 = 0.0351,
wR2 = 0.0867
R1 = 0.0898,
wR2 = 0.2118
R1 = 0.0913,
wR2 = 0.2126
R1 = 0.0443,
wR2 = 0.1008
R1 = 0.0458,
wR2 = 0.1016
R1 = 0.0596
wR2 = 0.1472
R1 = 0.0666,
wR2 = 0.1527
r
obtained (yield: 30%, based on H2L). Anal. Found: C, 49.00; H,
3.039; N, 3.829%. Calc. for C15H11O6NZn: C, 49.14; H, 3.025; N,
3.821%. IR (KBr, cmꢁ1): 3360w, 3120w, 1670m, 1600m, 1530vs,
1420s, 1320w, 1250w, 1180w, 787m, 764w, 661w.
2. Experimental
2.1. Materials and general methods
All reagents and solvents employed were commercially avail-
able and used without further purification. NMR spectra were ob-
tained using a Bruker Avance II 300 M instrument. Elemental
analyses were determined on an Elementar Vario ELIII analyzer.
The FT-IR spectra were recorded in the range 500–4000 cmꢁ1 using
KBr pellets on a Nicolet NEXUS 670 spectrophotometer. Thermo-
gravimetric analyses (TGA) were performed on a Mettler Toledo
TGA/SDTA851 instrument by heating from 25 to 800 °C under
flowing N2 atmosphere at a heating rate of 10 °C/min. Powder X-
ray diffraction (PXRD) patterns were recorded on recorded using
2.2.3. Synthesis of Zn5(L)2(OH)6 (3)
A mixture of Zn(NO3)2ꢀ6H2O (0.044 g, 0.15 mmol) and H2L
(0.014 g, 0.05 mmol) in 2 mL DMA/H2O (3:1, v:v) was sealed in a
Teflon-lined stainless autoclave and heated at 150 °C under auto-
geneous pressure for 30 h, and then cooled to room temperature.
Colorless prismatic crystals were obtained (yield: 46%, based on
H2L). IR (KBr, cmꢁ1): 3500w, 3380w, 1660m, 1600s, 1550vs,
1400vs, 1320m, 1250m, 1180w, 1010w, 856w, 779m, 731w.
a Rigaku (D/Max-Ultima IV) diffractometer equipped with Cu K
a
,
radiation, with a step size and a scan speed of 0.02° and 5° minꢁ1
2.2.4. Synthesis of [Ni(L)(H2O)2]ꢀH2O (4)
respectively. Simulated PXRD patterns were calculated with the
Mercury program using the single-crystal data [7]. Solid-state pho-
toluminescent spectra of complexes 2, 3, 5 and 6 were measured at
A mixture of Ni(NO3)2ꢀ6H2O (0.0204 g, 0.07 mmol) and H2L
(0.010 g, 0.035 mmol) in 2 mL DMA/H2O (1:3, v:v) was sealed in
a Teflon-lined stainless autoclave and subjected to solvothermal
condition at 150 °C for 30 h, and then cooled to room temperature.
Green prismatic crystals were obtained (yield: 87%, based on H2L).
Anal. Found: C, 45.24; H, 3.76; N, 3.54%. Calc. for C15H15O8NNi: C,
45.50; H, 3.82; N, 3.54%. IR (KBr, cmꢁ1): 3410w, 3020s, 1660vs,
1600s, 1510w, 1430m, 1380w, 1320w, 1250m, 1180w, 1110w,
1010w, 783m, 735w, 509m.
room temperature using
spectrometer.
a Varian Cary Eclipse fluorescence
2.2. Synthesis of H2L and complexes 1–7
H2L was synthesized according to the literature method [8].
2.2.1. Synthesis of Cd(L)(H2O) (1)
2.2.5. Synthesis of [Cd(L)(py)2H2O]ꢀDMFꢀ(C6H5Cl) (5)
A mixture of Cd(NO3)2ꢀ4H2O (0.043 g, 0.14 mmol) and H2L
(0.01 g, 0.035 mmol) in 5 mL DMF/H2O (1:1, v:v) was sealed in a
Teflon-lined stainless autoclave and heated at 100 °C under auto-
geneous pressure for 24 h, and then cooled to room temperature
(cooling rate: 0.1 °C/min). Colorless plate-like crystals of 1 were
obtained.
For complex 1, the synthesis was found to be fully reproducible.
However, the yield was very low and the resulting crystals were al-
ways accompanied by powders of un-determined composition. So it
is hard to carry out other characterizations.
A
mixture of Cd(NO3)2ꢀ4H2O (0.03 g, 0.1 mmol) and H2L
(0.014 g, 0.05 mmol) was dissolved in a 5 mL vial containing DMF
(0.5 mL) and H2O (0.5 mL). Slow diffusion of pyridine/C6H5Cl
(1:10, v:v) into the mixture resulted in the formation of 5 after
14 days (yield: 53%, based on H2L). IR (KBr, cmꢁ1): 3276m,
2930w, 2360w, 1660s, 1600s, 1490s, 1390vs, 1320s, 1260m,
1180m, 1100w, 1010w, 860m, 785m, 737w, 695w, 652w.
2.2.6. Synthesis of [Cd(L)(py)2]ꢀ2CH3OH (6)
A procedure similar to that for 5 was carried out to prepare 6,
except that C6H5Cl (5 mL) was replaced by CH3OH (5 mL). Colorless
block crystals of 6 were obtained (yield: 63%, based on H2L). IR
(KBr, cmꢁ1): 3280m, 3070w, 1940w, 1660s, 1600vs, 1520s,
1390vs, 1320s, 1253m, 1170w, 1010w, 864w, 787w, 700s.
2.2.2. Synthesis of Zn(L)(H2O) (2)
When the synthetic procedure for
1 was repeated with
Zn(NO3)2ꢀ6H2O (0.015 g, 0.053 mmol) instead of Cd(NO3)2ꢀ4H2O
in 2.5 mL DMF/H2O (3:2, v:v). Colorless plate-like crystals of 2 were

J.-J. Han et al. / Polyhedron 55 (2013) 249–258
251
2.2.7. Synthesis of [Mn (HL)2(py)2]ꢀ2DMF (7)
The coordination environment around CdII can be described as a
slightly distorted [CdO6] octahedron involving five carboxylate
oxygen atoms from four L2ꢁ ligands and an aqua ligand (O1w).
The relevant Cd–O (carboxylate oxygen: O1, O2, O4, O5) bond dis-
tances range from 2.127(1) to 2.380(1) Å, whereas the Cd–O1w
bond distance is 2.279(2) Å (Fig. 1a). Two CdII atoms are linked
A procedure similar to that for 5 was repeated to prepare 7, ex-
cept that Cd(NO3)2ꢀ4H2O was replaced by MnCl2ꢀ4H2O (0.014 g,
0.07 mmol). After 30 days, colorless block crystals of 7 were ob-
tained (yield: 45%, based on H2L). IR (KBr, cmꢁ1): 3290w, 1650vs,
1540vs, 1400s, 1330m, 1180w, 1100w, 1010w, 856w, 783w, 733w.
by two
clear cadmium unit with a Cdꢀ ꢀ ꢀCd separation of 3.528 Å, which are
further connected by
2-O,O0 carboxylate units with bond type
l
3-O,O,O0 carboxylate groups from two L2ꢁ to form a dinu-
2.3. X-ray crystallography
l
Cd1–O5 2.380(1) Å to generate an infinite double chain along the
Single-crystal X-ray diffraction data were collected on a Bruker
SMART Apex II diffractometer equipped with graphite-monochro-
c direction (Fig. 1a). There are two kinds of carboxylate coordina-
tion modes exist in 1, namely
l l
3-O,O,O0 and 2-O,O0, the latter
matic Mo Ka radiation (k = 0.71073 Å). Crystals were coated with
one further connected the chains into a three-dimensional (3D)
network via bond type Cd1–O4, 2.127(1) Å (Fig. 1b). From a topo-
logical point of view, the dinuclear cadmium SBU in complex 1
can be regarded as a 6-connected node with a point symbol of
{42.610.83}, and L2ꢁ acting as a 3-connected node with a point sym-
bol of {4.62}. Therefore, the whole structure thus can be repre-
sented as a {4.62}{42.610.83} network topology (Fig. S14).
paratone oil and the diffraction data were collected at 173 or
123 K cooled in a nitrogen stream. Frames were collected with
0.6° intervals in
of data was collected. Raw data collection and refinement were
done using SMART [9]. Data reduction was performed using SAINT
u and x for 30 s per frame such that a hemisphere
+
[10]. Absorption corrections were applied using the SADABS program
[11]. The structures were solved by direct method and refined by
full-matrix least-squares on F2 with anisotropic displacement
using SHELX-97 [12]. Non-hydrogen atoms were refined with aniso-
tropic displacement parameters during the final cycles. All the
hydrogen atoms attached to carbon atoms were placed in calcu-
lated positions and refined using the riding model.
3.1.2. Crystal structure of Zn(L)(H2O) (2)
When the synthetic procedure for
1 was repeated with
Zn(NO3)2ꢀ6H2O instead of Cd(NO3)2ꢀ4H2O, a quite different struc-
ture of complex 2 was obtained. The asymmetric unit of 2 is com-
posed of one ZnII atom, one L2ꢁ and an aqua ligand. The ZnII atom is
in a distorted tetrahedral geometry, being coordinated by one aqua
ligand (Zn–O1w = 1.980(3) Å), three carboxylate oxygen atoms
from three L2ꢁ ligands (Zn–O = 1.931(3)–1.985(3) Å). Further
expansion of the structure through the bis(monodentate)/mono-
dentate carboxylates create a layer (Fig. 2a). Notably the aqua li-
gand plays a key role in the structure of 2: (1) the tetrahedral
coordination environment of ZnII and L2ꢁ is reinforced by intermo-
lecular hydrogen bonding between the aqua ligand and the carbox-
3. Results and discussion
3.1. Crystal structures
3.1.1. Crystal structure of Cd(L)(H2O) (1)
Single-crystal X-ray diffraction analysis revealed that complex 1
crystallizes in the monoclinic space group P21/c. The asymmetric
unit contains one CdII atom, one L2ꢁ ligand and an aqua ligand.
Fig. 1. (a) Portion of the infinite chain of Cd(L)(H2O) (1) viewed along the c direction; (b) Schematic showing of the 3D structure of 1 viewed along the a direction constructed
from linkage of chains via bond type Cd1–O4.

252
J.-J. Han et al. / Polyhedron 55 (2013) 249–258
ylate group with the aqua ligand serving as donors and the carbox-
ylate oxygen atoms as acceptors [O1w–H1wbꢀ ꢀ ꢀO1 (x + 1, ꢁy + 1,
A prominent structural feature of 3 is the zinc-hydroxide layers
generated from connection of ZnII via l3
l4 hydroxyl oxygen
/
z + 1/2),
O1wꢀ ꢀ ꢀO1 = 2.689 Å,
H1wbꢀ ꢀ ꢀO1 = 1.85 Å,
O1w–
atoms. Each Zn1 atom is connected to six other Zn atoms (three
Zn2, two Zn1, and one Zn3) via hydroxyl groups, while each Zn2
atom is joined with seven other Zn atoms (three Zn1, two Zn3,
and two Zn2) via hydroxyl groups. In addition, each Zn3 atom is
linked to total six Zn atoms (four Zn2 and two Zn1) through the hy-
droxyl groups, leading to the formation of 2D zinc-hydroxide lay-
ers with Zn3(OH)3, Zn4(OH)5, Zn2(OH)2 circular units (Fig. 3b),
which are quite different from those in the other coordination
polymers incorporating Cd-hydroxide or Fe-hydroxide layers
[13]. Adjacent layers are further pillared by L2ꢁ ligands functioning
H1wbꢀ ꢀ ꢀO1 = 167.9°]; (2) the layers are further connected by
hydrogen bonding with the aqua ligand serving as donors and
the carboxylate oxygen as acceptors into a 3D architecture
[O1w–H1waꢀ ꢀ ꢀO1 (x + 1, y ꢁ 1, z + 1), O1wꢀ ꢀ ꢀO1 = 2.655 Å,
H1waꢀ ꢀ ꢀO1 = 1.799 Å, O1w–H1waꢀ ꢀ ꢀO1 = 158.9°] (Fig. 2b).
3.1.3. Crystal structure of Zn2.5(L)(OH)3 (3)
Single-crystal diffraction study revealed that complex 3 crystal-
lizes in monoclinic space group C2/c. There are two and a half crys-
tallographic independent ZnII atoms, one L2ꢁ and three hydroxyl
groups. In 3, Zn1 atom adopts a distorted triangular bipyramid
geometry, being surrounded by two hydroxyl groups [Zn–O (O8,
O7c) = 2.066(3)–2.073(3) Å] at the apical positions and two hydro-
xyl oxygen atoms [Zn–O (O6, O7b) = 2.018(4)–2.029(6) Å] and one
carboxylate oxygen atom at the basal positions [Zn–O
(O1a) = 1.987(4) Å]; Zn2 is six-coordinated with a distorted octa-
hedral geometry, and the metal center is surrounded by four hy-
droxyl oxygen atoms [Zn–O (O6, O7, O8, O9) = 1.984(4)–
2.4512(7) Å] and two carboxylate oxygen atoms from two individ-
ual L2ꢁ ligands [Zn–O (O5, O2d) = 2.062(4)–2.219(4) Å]. Zn3 lies in
a 2-fold axis and adopts a slightly distorted triangular bipyramid
geometry, coordinated by two carboxylate oxygen atoms [Zn–O
(O4, O4e) = 2.231(4) Å] from two L2ꢁ ligands at the apical positions
and three hydroxyl oxygen atoms [Zn–O (O8, O8e,
O9b) = 1.928(6)–1.952(4) Å] at the basal positions.
in the l
2-O,O0 coordination mode to generate a 3D network.
3.1.4. Crystal structure of [Ni(L)(H2O)2]ꢀH2O (4)
X-ray crystallography reveals that 4 crystallizes in the mono-
clinic space group Cc. The asymmetric unit consists of one NiII
atom, one L2ꢁ, two aqua ligands and one guest water molecule.
In 4, each NiII ion is six-coordinated in a octahedral geometry
involving two carboxylate oxygen atoms from two different L2ꢁ li-
gands [Ni–O (O2, O3a) = 1.967(7)–1.977(7) Å] and four aqua li-
gands [Ni–O (O1w, O2w) = 2.082(9)–2.115(9) Å] (Fig. 4a). In the
two carboxylate units of L2ꢁ, only one carboxylate of L2ꢁ adopts
a syn–syn bidentate coordination mode. The NiII atoms are linked
by aqua ligands, together with the syn–syn bidentate carboxylate
group, to generate a 1D chain extending along the a direction
(Niꢀ ꢀ ꢀNi = 3.009 Å). The most interesting feature of 4 arises from
the supramolecular level involving the uncoordinated carboxylate
Fig. 2. (a) Ball-and stick showing of the layer structure of complex Zn(L)(H2O) (2); (b) Three-dimensional architecture of 2 viewed the c direction. Hydrogen bonds are
represented by broken lines.

J.-J. Han et al. / Polyhedron 55 (2013) 249–258
253
Fig. 3. (a) Local coordination environments of the Zn1, Zn2, Zn3 center in Zn5(L)2(OH)6 (3) (hydrogen atoms were omitted for clarity); (b) View of 2D zinc-hydroxide layers of
3; (c) View of the 3D coordination network of 3.
unit, aqua ligand and guest water molecule. As shown in Fig. 4b,
the infinite Ni(II) chains are interconnected by O1w–Hꢀ ꢀ ꢀO5,
O2w–Hꢀ ꢀ ꢀO4 hydrogen bonds to form a 2D layer structure along
the b axis. It is noteworthy that O3w plays a dual role serving as
a hydrogen bonding donor as well as an acceptor to construct a
3D structure by forming four hydrogen bonds O1w–Hꢀ ꢀ ꢀO3w,
O2w–Hꢀ ꢀ ꢀO3w, O3w–Hꢀ ꢀ ꢀO4, O3w–Hꢀ ꢀ ꢀO5 (the distances are in
the range of 2.64–2.66 Å) to generate a hybrid 3D structure
(Fig. 4c).
pyridine molecules, one aqua ligand, one guest DMF molecule, and
one C6H5Cl molecule. Each CdII atom adopts a pentagonal bipyramid
geometry being coordinated by two pyridine molecules at the axial
positions (Cd–N = 2.334(7)–2.371(7) Å) and four oxygen atoms from
the chelating carboxylates of two L2ꢁ (Cd–O = 2.345(6)–2.475(6) Å)
and one aqua ligand in the equatorial plane (Cd–O
(aqua) = 2.334(6) Å) (Fig. 5a). Linkage of L2ꢁ and CdII gives rise to
the 1D chain. Each aqua ligand (O1w)from one chain forms three dif-
ferent hydrogen bonds (O1W–Hꢀ ꢀ ꢀO2, O1W–Hꢀ ꢀ ꢀO4, O1W–Hꢀ ꢀ ꢀO2)
with two carboxylate oxygen atoms (O2 and O4) from another chain
to generate a layer (Fig. 5a). The layers are further mutually interdig-
itated to create a stable 3D assembled framework, with the cavities
occupied by guest DMF and C6H5Cl arranged alternatively (Fig. 5b).
3.1.5. Crystal structure of [Cd(L)(py)2H2O]ꢀDMFꢀ(C6H5Cl) (5)
Complex 5 crystallizes in the monoclinic space group C2/c. Its
asymmetric unit contains one CdII atom, one L2ꢁ, two coordinated

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J.-J. Han et al. / Polyhedron 55 (2013) 249–258
Fig. 4. (a) Local coordination environment of the NiII center in [Ni(L)(H2O)2]ꢀH2O (4); (b) Two-dimensional layer of 4 connected by hydrogen bonds; (c) Three-dimensional
hydrogen-bonded network of 4.
Note that the 3D framework is reinforced by
p
–
p
stacking between
L2ꢁ ligands in complex 6. The asymmetric unit contains one CdII
atom, one L2ꢁ, two coordinated pyridine molecules and two guest
CH3OH molecules. It is worth to note that the seven-coordinated
CdII atom shows a pentagonal–bipyramidal coordination geometry.
The metal center was coordinated by five carboxylate oxygen
atoms in the equatorial plane (Cd–O = 2.325(2)–2.639(3) Å) and
two pyridine nitrogen atoms (Cd–N = 2.287(8)–2.295(8) Å) locating
at the apical position (Fig. 6a). Each binuclear motif is further linked
to four identical motifs through four L2ꢁ ligands, leading to a 2D
coordination layer (Fig. 6b). Taking the binuclear motifs as 4-con-
necting nodes and the ligands as linkers, the layer can be consid-
ered to be a (4,4) net. The dimensions of the rhombic windows of
adjacent pyridine rings (centroid-to-centroid distance between
adjacent pyridine rings is 3.774 Å). It should be pointed out that
hydrogen bonds exist between the skeleton and the guest DMF mol-
ecules (N1–Hꢀ ꢀ ꢀO6DMF is about 2.869 Å). Another interesting feature
is the p–p stacking interactions between pairs of C6H5Cl guest mol-
ecules existing in the structure (centroid-to-centroid distance be-
tween C6H5Cl is 3.845 Å).
3.1.6. Crystal structure of [Cd(L)(py)2]ꢀ2CH3OH (6)
Two-dimensional square-grid structure was generated from
linkage of Cd2 units (Cdꢀ ꢀ ꢀCd separation of 3.936 Å) with

J.-J. Han et al. / Polyhedron 55 (2013) 249–258
255
Fig. 5. (a) Local coordination environments of the CdII center in [Cd(L)(py)(H2O)]ꢀ(DMF)ꢀ(C6H5Cl) (5) (hydrogen atoms were omitted for clarity); (b) Two-dimensional
hydrogen-bond layer of 5; (c) View of three-dimensional assembled structure, with the cavities are occupied by guest DMF and C6H5Cl molecules.
the layer are about 17.91 ꢂ 16.46 Å which is large enough to
accommodate the guest molecule (the shortest Cdꢀ ꢀ ꢀCd distance
spanned by the two independent L2ꢁ ligands). The moderate strong
hydrogen bonding interactions can be found between the guest
molecules CH3OH and the acylamide group of about 2.8 Å.
form a linear [Mn(py)(HL)] chain with Mnꢀ ꢀ ꢀMn contact distance
of about 16.139 Å. Moreover, the [Mn(py)(HL)] chains are rein-
forced by intermolecular hydrogen bonding between carboxylic
acid group and carboxylate unit (d(Dꢀ ꢀ ꢀA) = 2.469 Å, d(Hꢀ ꢀ ꢀA)
1.652 Å). Adjacent chains are arranged parallel to each other by
forming hydrogen bonding (acylamide) N–Hꢀ ꢀ ꢀO(DMF) about
3.035 Å to create a 2D assembled sheet, with DMF guest molecules
hosted inside via hydrogen bonding between the acylamide group
of HL and carbonyl group of DMF molecules d(Dꢀ ꢀ ꢀA) = 3.035 Å,
d(Hꢀ ꢀ ꢀA) 2.259 Å (Fig. 7b).
3.1.7. Crystal structure of [Mn0.5(HL)(py)]ꢀDMF (7)
Determination of the structure of complex 7 by single-crystal X-
ray diffraction analysis indicates that 7 crystallizes in the triclinic
ꢀ
space group P1. Its asymmetric unit contains a divalent Mn atom
lying on a crystallographic inversion center, one mono-deprontat-
ed HLꢁ anion, one pyridine ligand and one guest DMF molecule of
crystallization. Operation of the inversion center at the metal cen-
ter revealed that the MnII center is in an octahedral geometry,
being coordinated by two pyridine molecules (Mn–
N = 2.257(1) Å) and four carboxylate oxygen atoms (Mn–
O = 2.142(2)–2.156(1) Å) from four different HLꢁ ligands (Fig. 7a).
It is noteworthy that one carboxyl group of H2L is not ionized
and therefore giving rise to HL- instead of L2ꢁ. Ligands HLꢁ in
bis(mondentate) coordination mode connect the MnII atoms to
The preparation of coordination polymers is a complicated pro-
cess and can be influenced by many factors such as molar ratio, sol-
vents employed, reaction temperature, pH etc. Subtle change in the
reaction conditions may result in complete different structure. For
instance, reaction of H2L Zn(NO3)2ꢀ6H2O in DMF at 80 °C gave rise
to NJU-Bai1 exhibiting a 2-fold interpenetrated pcu-type network.
Its structure is quite different from that of 1 obtained in DMF–H2O
system at 100 °C [8]. Also, complexes 1 and 2 in this report showed
entirely different structures under similar reaction conditions with
different metal ions.

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J.-J. Han et al. / Polyhedron 55 (2013) 249–258
Fig. 6. (a) Local coordination environments of the CdII center in [Cd(L)(py)2]ꢀ2CH3OH (6) (hydrogen molecules were omitted for clarity); (b) Two-dimensional (4,4) network
based on the binuclear Cd2 units.
3.2. Thermal stability analysis and powder X-ray diffraction (PXRD)
analysis
methanol (calcd, 5.5%). The loss of two coordinated pyridine mol-
ecules was found in the range of 85–280 °C (observed 26.9%; calcd,
25.6%). When the temperature is higher than 400 °C, the frame-
work began to collapse to give CdO as the final residue (observed
21.3%; calcd, 20.7%) (Fig. S5). The TGA of 7 shows the first weight
loss of 16.7% (calcd, 15.9%) around 186 °C, corresponding to the
loss of guest DMF molecule. The second weight loss of 18.0% (calcd,
17.1%) around 397 °C corresponds to the loss of two coordinated py
molecules. When the temperature is higher than 400 °C, the
remaining HLꢁ units were removed (observed 31.2%; calcd,
30.6%) and the collapse of the framework began. The final residue
is MnO (observed 23.7%; calcd, 23.0%) (Fig. S6).
Thermogravimetric analyses (TGA-DSC) are performed on crys-
talline samples to examine the thermal stability.
TGA data for the crystalline sample 2 indicates a 4.3% weight
loss during 18–187 °C, corresponding to the loss of one coordi-
nated water molecule (calcd, 4.9%). No further weight loss is ob-
served from 187 to 425 °C. The decomposition begins at 425 °C
accompanied by a large exothermic peak (Fig. S1). For the crystal-
line sample 3, the weight loss of 5.2% at 17–346 °C corresponds to
the loss of three OH groups (calcd, 5.8%). Decomposition of the
framework begins at 425 °C and the final residue is ZnO (observed
49.3%, calcd, 48.9%) (Fig. S2). From the TGA of complex 4, the
weight loss of 9.0% during 185–220 °C corresponds to the loss of
two coordinated water molecules (calcd, 9.1%). Then decomposi-
tion occurred with a large exothermic peak within the temperature
range of 405–450 °C to give NiO as the final product (observed
38.5%, calcd, 37.9%) (Fig. S3). The TGA curve of 5 exhibits a large
weight loss (43.7%) at 25–252 °C, corresponding to the loss of all
the coordinated water and pyridine molecules, the guest C6H5Cl
and DMF in the structure (calcd, 44.5%). Decomposition began at
temperature of 397 °C. The final residue is CdO (observed 17.5%;
calcd, 16.9%) (Fig. S4). As to 6, one guest CH3OH molecule was lost
before TGA test. The TGA curves shows the first weight loss of 5.2%
in the range of 25–85 °C, corresponding to the loss of the other
PXRD analyses are carried out to check the structural identity.
For 2–7, the measured PXRD pattern closely matches the one sim-
ulated from single-crystal diffraction data, indicating the phase
purity (Figs. S7–S12).
3.3. Luminescent properties of 2, 3, 5 and 6
Luminescent properties of d10 metal-containing complexes
have attracted much attention due to their potential applications
in electroluminescent display, chemical sensors, and photochemis-
try. Therefore, in this work, the luminescent properties of com-
plexes 2, 3, 5 and 6 as well as the free H2L ligand were
investigated in the solid state at room temperature (Fig. 8). The
main emission peaks of the free H2L at 437 nm (kex = 348 nm)

J.-J. Han et al. / Polyhedron 55 (2013) 249–258
257
Fig. 7. (a) Local coordination environments of the MnII center in [Mn (HL)2(py)2]ꢀ2DMF (7); (b) View of two-dimensional assembled layer along the a axis.
for the four complexes compared with the free H2L under the same
conditions may mainly originate from the coordination interac-
tions between the metal atom and the ligand, which enhanced
its conformational rigidity and then decreased the nonradiative
energy loss [14]. It is noteworthy that a similar emission band
at about 450 nm has also been observed previously in other
H2L-based Zn-containing coordination polymers.
Besides, in comparison with the free ligand, red-shifts of about
8, 15, 10, 6 nm are found for 2, 3, 5 and 6, respectively. These re-
sults suggest that 2, 3, 5 and 6 may be good candidates for poten-
tial hybrid inorganicꢁorganic photoactive materials.
4. Conclusions
In summary, the combination of coordination bond, hydrogen
bond and p–p stacking leads to a series of coordination polymers
showing interesting solid-state structures. Complexes 1 and 3
show 3D dense architecture built by coordination bond only, while
Fig. 8. Solid-state emission spectra for 2, 3, 5 and 6.
complexes 2, 5, 6 and 7 are constructed by coordination bond, p–p
stacking together with hydrogen bonding into 3D supramolecular
frameworks. Weak interactions play an important role in con-
structing above complexes. In addition, the luminescent emission
intensities of complexes 2, 3, 5 and 6 are much stronger than that
of the ligand, so they may be suitable candidates for fluorescent
materials. Our continue research will further expand to other reac-
tion systems to obtain new coordination polymers with fascinating
structures and potential applications.
may be ascribed to the n ? p⁄ or
p ?
p⁄ transitions (Fig. S13).
Complexes 2, 3, 5 and 6 show emission peaks at 445 nm
(kex = 348 nm), 452 nm (kex = 342 nm), 447 nm (kex = 320 nm) and
443 nm (kex = 334 nm), respectively (Fig. S14). The emission peaks
of 2, 3, 5 and 6 are close to that of the free H2L, so the emission
peaks of the four complexes can probably be attributed to the
intraligand fluorescent emission. The enhancement of luminescence

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J.-J. Han et al. / Polyhedron 55 (2013) 249–258
(e) B.-L. Chen, S.-Q. Ma, F. Zapata, F.R. Fronczek, E.B. Lobkovsky, H.-C. Zhou,
Acknowledgements
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(f) C.-C. Ji, L.-F. Huang, J. Li, H.-G. Zheng, Y.-Z. Li, Z.-J. Guo, Dalton Trans. 39
(2010) 8240;
(g) Y.-J. Cui, Y.-F. Yue, G.-D. Qian, B.-L. Chen, Chem. Rev. 112 (2011) 1126;
(h) C. Benelli, D. Gatteschi, Chem. Rev. 102 (2002) 2369;
This work was supported by the National Natural Science Foun-
dation of China (NSFC No. 20801018), Shanghai education develop-
ment foundation for financial support (Grant No.2008CG31) and
Shanghai Phosphor Project of Science and Technology for Excellent
Young Researcher (10QA1402000).
(i) J.A. Alonso, Chem. Rev. 100 (2000) 637;
(j) M. Yoon, R. Srirambalaji, K. Kim, Chem. Rev. 112 (2012) 1196.
[3] S.K. Seth, D. Sarkarc, T. Kar, CrystEngComm 13 (2011) 4528.
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Appendix A. Supplementary data
[6] (a) N.L.S. Yue, D.J. Eisler, M.C. Jennings, R.J. Puddephatt, Inorg. Chem. 43 (2004)
7671;
(b) S. Hong, Y. Zou, D. Moon, M.S. Lah, Chem. Commun. (2007) 1707;
(c) D.K. Kumar, A. Das, P. Dastidar, CrystEngComm 9 (2007) 895;
(d) S. Hasegawa, S. Horike, R. Matsuda, S. Furukawa, K. Mochizuki, Y.
Kinoshita, S. Kitagawa, J. Am. Chem. Soc. 129 (2007) 2607;
(e) Z.-Q. Qin, M.C. Jennings, R.J. Puddephatt, Chem. Eur. J. 8 (2002) 735;
(f) D. Moon, S. Kang, J. Park, K. Lee, R.P. John, H. Won, G.H. Seong, Y.S. Kim, G.H.
Kim, H. Rhee, M.S. Lah, J. Am. Chem. Soc. 128 (2006) 3530;
(g) Y. Zhang, Q. Wang, Y.-J. Xiao, J. Han, X.-L. Zhao, Polyhedron 33 (2012) 127.
[7] C.F. Macrae, P.R. Edgington, P. McCabe, E. Pidcock, G.P. Shields, R. Taylor, M.
Towler, J.J. van de Streek, Appl. Crystallogr. 39 (2006) 453.
[8] J. Duan, J. Bai, B. Zheng, Y. Li, W. Ren, Chem. Commun. 47 (2011) 2556.
[9] SMART (Version 6.532), Program for Bruker CCD X-ray Diffractometer Control,
Bruker AXS Inc., Madison, WI, 2005.
[10] Bruker, SMART 5.0 and SAINT 4.0 for Windows NT, Area Detector Control and
Integration Software, Bruker Analytical X-ray Systems Inc., Madison, WI, 1998.
[11] G.M. Sheldrick, SADABS: Program for Empirical Absorption Correction of Area
Detector Data, University of Göttingen, Göttingen, Germany, 1996.
[12] G.M. Sheldrick, SHELXTL 5.1 for Windows NT: Structure Determination Software
Programs, Bruker Analytical X-ray Systems Inc., Madison, WI, 1997.
[13] (a) M.-L. Tong, S. Hu, J. Wang, S. Kitagawa, S.W. Ng, Cryst. Growth Des. 5
(2005) 837;
CCDC 892604–892610 contains the supplementary crystallo-
graphic data for complexes 1–7, respectively. These data can be ob-
tained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Cen-
tre, 12, Union Road, Cambridge CB 21 EZ, UK; fax: (+44) 1223-336-
033; or e-mail: deposit@ccdc.cam.ac.uk. Supplementary data asso-
ciated with this article can be found, in the online version, at
http://dx.doi.org/10.1016/j.poly.2013.03.029.
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