Preparation and characterization of two supramolecular complexes with 5-amino-2,4,6-triiodoisophthalic acid under N-donor auxiliary ligand intervention

Article abstract of DOI:10.1016/j.ica.2010.12.038

Assemblies of 5-amino-2,4,6-triiodoisophthalic acid (H₂ATIBDC) with Cd(II) and Zn(II) in the presence of N-donor auxiliary ligand, 1,4-bis(1,2,4-triazol-1-yl)butane (btb), at ambient conditions yield two new supramolecular complexes, [Cd(ATIBDC

Full text of DOI:10.1016/j.ica.2010.12.038

Inorganica Chimica Acta 368 (2011) 49–57
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Preparation and characterization of two supramolecular complexes
with 5-amino-2,4,6-triiodoisophthalic acid under N-donor auxiliary
ligand intervention
a
b
Kou-Lin Zhang a, , Yan Chang , Seik Weng Ng
⇑
a Key Laboratory of Environmental Material and Environmental Engineering of Jiangsu Province, College of Chemistry and Chemical Engineering,
Yangzhou University, Yangzhou 225002, China
b Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 29 July 2010
Accepted 15 December 2010
Available online 24 December 2010
Assemblies of 5-amino-2,4,6-triiodoisophthalic acid (H2ATIBDC) with Cd(II) and Zn(II) in the presence of
N-donor auxiliary ligand, 1,4-bis(1,2,4-triazol-1-yl)butane (btb), at ambient conditions yield two new
supramolecular complexes, [Cd(ATIBDC)(btb)(H2O)2]Á3H2O (1), and [Zn(ATIBDC)(btb)]Á2H2O (2). Gener-
ally, these two complexes display 1D ATIBDC2À-bridged coordination arrays. Distinct extended 3D net-
work architectures are further constructed with the help of weak secondary interactions especially
aromatic stacking, halogen bonding, and hydrogen bonding as supramolecular driving forces. It is worthy
Keywords:
Cd(II) complex
Zn(II) complex
Crystal structures
Supramolecular networks
Fluorescence
to mention that halogen bonds (C–IÁ Á Á
p
and C–IÁ Á ÁN/O) play important roles in the supramolecular
assembly. The pentameric cluster (H2O)5 in 1 assembles into highly ordered helical infinite chains. Com-
plex 2 exhibits the fascinating single-walled tube-like chain structure. It loses crystallinity rapidly in the
air and leads to the formation of [Zn(ATIBDC)(btb)]ÁH2O (2A). Thermal stabilities and solid state fluores-
cent properties of complexes 1 and 2A have been studied.
Ó 2010 Elsevier B.V. All rights reserved.
1. Introduction
At present, we are focusing our attention on using iodine-
containing 5-amino-2,4,6-triiodoisophthalic acid (H2ATIBDC) as
The aim of contemporary supramolecular chemistry and crystal
engineering is the development of new crystalline materials with
various functions and possible applications such as molecular
adsorption, magnetism, nonlinear optics, molecular sensing, heter-
ogeneous catalysis, and photoactive materials although the ra-
tional design and synthesis of metal–organic frameworks (MOFs)
with target structure and function still remains a long-term chal-
lenge [1–11]. The construction of supramolecular architectures
depends on the combination of several factors, such as the coordi-
nation geometry of metal ions, the nature of organic ligands, the
use of noncovalent interactions (hydrogen bonding, halogen bond-
the organic moiety to assemble with transition metal ions in the
presence of N-donor auxiliary ligand, which is based mostly upon
the following considerations: (1) Three I atoms in H2ATIBDC are
potential interaction sites for forming C–IÁ Á ÁN/O, C–IÁ Á ÁI, or C–
IÁ Á Á
p halogen bonds which may help to extend the linkage into
high dimensional supramolecular network due to their specific
directional nature and relatively high halogen bonding energy.
(2) ATIBDC2À is a rigid aromatic dicarboxylate ligand and thus
can play the role of a bridging rod. Therefore, a structural predic-
tion of the resulting polymeric complexes may be possible to some
extent. Furthermore, due to the presence of aromatic/hetero rings
of ATIBDC2À and N-donor auxiliary ligand in the assembled system,
ing, p–p interactions, or their combination in different ways) and
sometimes the reagent ratio [12–15]. So, understanding how these
considerations affect metal coordination and influence crystal
packing is at the forefront of controlling coordination supramolec-
ular arrays. It has been documented that the geometries of organic
ligands play crucial roles in determining the resulted polymeric
structures [16].
the delicate
p p stacking interactions are available to play an sig-
Á Á Á
nificant role in regulating the resulting supramolecular networks.
Several novel complexes with the ATIBDC2À ligand have been re-
ported [17,18].
We had finished a systematic study focusing on the p-block me-
tal Pb(II) with ATIBDC2À ligand [19]. In this paper, we will describe
our recent research results of the synthesis, crystallography, and
properties of two supramolecular complexes with H2ATIBDC in or-
der to further understand the coordination chemistry of H2ATIBDC
with d10 metal ions, the roles of three I atoms in the supramolecu-
lar assembly. With the introduction of organonitrogen auxiliary
⇑
Corresponding author. Tel./fax: +86 514 87695171.
E-mail addresses: koulinzhang2002@yahoo.com, klzhang@yzu.edu.cn (K.-L.
Zhang).
0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2010.12.038

50
K.-L. Zhang et al. / Inorganica Chimica Acta 368 (2011) 49–57
Table 1
ligand, 1,4-bis(1,2,4-triazol-1-yl)butane (btb), two interesting
supramolecular complexes, [Cd(ATIBDC)(btb)(H2O)2]Á3H2O (1)
and [Zn(ATIBDC)(btb)]Á2H2O (2), have been obtained. In this work,
we attempt to demonstrate the roles of supramolecular interac-
Crystal data and structure refinement for the complexes 1–2.
1
2
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
a (Å)
C
16H24CdI3N7O9
C16H18I3N7O6Zn
850.44
296(2)
0.71073
Orthorhombic
Pna21
16.511(3)
14.854(2)
10.1159(15)
90
tions, such as hydrogen bonding and halogen bonding (C–IÁ Á Á
p,
951.52
293(2)
C–IÁ Á ÁN/O), in engineering the resultant crystalline architectures.
The pentameric water cluster (H2O)5 in 1 assembles into highly or-
dered helical infinite chains. Complex 2 exhibits a fascinating sin-
gle-walled tube-like chain structure and desolvates partly in the
air forming [Zn(ATIBDC)(btb)]ÁH2O (2A). Solid state fluorescent
properties of 1 and 2A have been investigated.
0.71073
Monoclinic
P21/n
8.1689(4)
20.2307(9)
17.2518(8)
90
b (Å)
c (Å)
a
(°)
b (°)
96.9830(10)
90
2829.9(2)
4
2.233
4.099
90
90
2480.9(6)
4
2.277
c
(°)
2. Experimental
V (Å3)
Z
2.1. Materials and characterization
Dcalc (mg/m3)
Absorption coefficient (mmÀ1
F(0 0 0)
)
4.769
1600
The nitrogenous auxiliary ligand, 1,4-bis(1,2,4-triazol-1-yl)bu-
tane (btb), was synthesized according to the literature method
[20]. The other reagents were purchased commercially. Elemental
analyses (C, H, and N) were carried out on a 240 C Elemental ana-
lyzer. FT-IR spectra (4000–400 cmÀ1) were recorded from KBr pel-
let in Magna 750 FT-IR spectrophotometer. Solid state emission
spectra were recorded using an F 4500 fluorescence spectrometer.
Both the excitation and emission pass width are 5.0 nm. Thermo-
gravimetric analysis (TGA) was taken on NETZSCH STA 409 PG/
PC instrument from room temperature to 800 °C at a heating rate
of 10 °C/min in N2. X-ray powder diffraction data were collected
at room temperature on a computer-controlled Bruker D8 Ad-
1792
h range for data collection (°)
Index ranges
1.56–27.50
À10 6 h 6 10
À26 6 k 6 23
À21 6 l 6 21
17 765
6452
[R(int) = 0.0222]
99.40%
1.84–27.42
À21 6 h 6 21
À17 6 k 6 19
À12 6 l 6 13
20 561
5466
[R(int) = 0.0466]
99.60%
Reflections collected
Unique (Rint
)
Completeness to h = 27.5
Maximum and minimum
transmission
0.406 and 0.226
0.424 and 0.249
Goodness-of-fit on F2
1.047
1.066
Final R indices [I > 2
r
(I)]
R1 = 0.0285
wR2 = 0.0775
R1 = 0.0352
wR2 = 0.0809
1.927 and À1.019
R1 = 0.0323
wR2 = 0.0723
R1 = 0.0420
wR2 = 0.0879
0.982 and À0.784
R indices (all data)
vanced XRD diffractometer equipped with Cu K
a monochromator
(k = 1.5418 Å) at a scanning rate 0.04°/s from 5° to 50°.
Largest different peak and hole
(e ÅÀ3
)
2.2. Crystal structure determination
btb (0.019 g, 0.100 mmol), H2ATIBDC (0.112 g, 0.200 mmol), and
NaOH (0.8 ml, 0.5 mol/l) were used. Pale yellow crystals were
formed. Complex 2 loses crystallinity in the open air and turns into
the pale yellow powder formulated as [Zn(ATIBDC)(btb)]ÁH2O (2A)
(44% based on btb). Anal. Calc. for C16H16I3N7O5Zn: C, 23.09; H,
1.94; N, 11.78. Found: C, 22.89; H, 1.89; N, 11.69%.
Crystallographic data were collected at 293(2) K with a Siemens
SMART CCD diffractometer using graphite-monochromated
(Mo Ka) radiation (k = 0.71073 Å), w and x scans mode. The struc-
tures were solved by direct methods and refined by Full-Matrix
least-squares on F2 method. Intensity data were corrected for Lor-
enz and polarization effects and a multi-scan absorption correction
was performed. All non-hydrogen atoms were refined anisotropi-
cally. The carbon-bound hydrogen atoms of all the complexes were
added geometrically. The oxygen-bound hydrogen atoms of water
molecules were located in the difference Fourier map and then
kept fixed in that position. The contribution of these hydrogen
atoms was included in the structure factor calculations. Two oxy-
gen atoms (O4W and O5W) of lattice water molecules in 1 were
disordered over two positions. All calculations were carried out
on a PC computer using SHELXL-97 program [21]. Details of crystal
data, collection, and refinement are listed in Table 1.
3. Results and discussion
3.1. Synthesis of the complexes
The formation of the products is sensitive to synthetic condi-
tions. The hydrothermal method is not suitable for the syntheses
of these two complexes since the ATIBDC2À ligand decomposes un-
der hydrothermal condition. Therefore, the complexes 1–2 have
been obtained under soft ambient conditions. NaOH is used to neu-
tralize the acid. Interestingly, the molar ratio of H2ATIBDC:NaOH is
important for the formation of 1–2. The molar ratio of H2ATI-
BDC:NaOH = 1:2 was used to synthesize the complexes 1–2. Other-
wise the polycrystals or cotton-like solids were obtained.
2.3. Synthesis of [Cd(ATIBDC)(btb)(H2O)2]Á3H2O (1)
A
mixture of H2ATIBDC (0.056 g, 0.100 mmol) and NaOH
(0.4 ml, 0.5 mol/l) was dissolved in water (5 ml) and then an aque-
ous solution of CdCl2Á2.5H2O (0.046 g, 0.200 mmol) was added
while stirring. To this solution btb (0.019 g, 0.100 mmol) in water
(5 ml) was added and then filtered. Pale yellow polyhedral crystals
were collected (61% based on H2ATIBDC). Anal. Calc. for C16H24CdI3-
N7O9: C, 20.20; H, 2.54; N, 10.30. Found: C, 20.11; H, 2.47; N,
10.21%.
Complex 2 loses crystallinity rapidly in the open air, resulting in
the formation of the powder [Zn(ATIBDC)(btb)]ÁH2O (2A) sup-
ported by the elemental and thermogravimetric analysis.
3.2. Structure description of [Cd(ATIBDC)(btb)(H2O)2]Á3H2O (1)
Complex 1 crystallizes in monoclinic system with space group
P21/n. There are one Cd(II) atom, one ATIBDC2À anion, two coordi-
nated water molecules, and three lattice water molecules in the
asymmetric unit (Fig. 1A). The Cd(II) lies in a distorted pentagonal
bipyramid environment, in which the equatorial plane contains O1,
O2, and O3 atoms from two carboxylate groups of two different
2.4. Synthesis of [Zn(ATIBDC)(btb)]Á2H2O (2)
Complex 2 can be obtained following the same synthetic proce-
dure as that for 1 except that Zn(NO3)Á6H2O (0.060 g, 0.200 mmol),

K.-L. Zhang et al. / Inorganica Chimica Acta 368 (2011) 49–57
51
Fig. 1. (A) View of the coordination environment of Cd(II) and the conformation of btb in 1. Symmetry transformations #1 Àx + 3/2, y + 1/2, Àz + 3/2. (B) 1D loop-like chain,
showing the conformation of btb ligand and the coordination mode of ATIBDC2À. (C) Hydrogen-bonded 2D layer. All the disordered positions of O4W and O5W are shown. (D)
Halogen-bonded 2D layer. (E) 3D MOF along [0 1 0] through both the H-bonding and halogen bonding between the chains.
ATIBDC2À ligands and O1W and O2W from two coordinated water
molecules. The two triazole nitrogen atoms N2 and N7 from two
different btb ligands occupy the axial positions with N2–Cd1–N7
angle of 168.71(13)° (Table 2). The btb ligand exhibits the trans–
trans–gauche conformation (Scheme 1). On the other hand, each
ATIBDC2À ligand coordinates with two Cd(II) atoms. One carboxyl-
ate group adopts a k2-chelating coordination mode, while the other
carboxylate group adopts a k1 monodentate coordination mode. So,
the ATIBDC2À ligand exhibits the k1–k2-l2 coordination mode
(Scheme 2). As shown in Fig. 1B, both the btb and ATIBDC2À ligand
bridge the Cd1 and Cd2 atoms to form an infinite 1D loop-like
chain with the nearest CdÁ Á ÁCd distance of 10.125 Å.
Interestingly, the acyclic pentameric water cluster (O1W, O2W,
O3W, O4W, O5W) assembles into 1D helical water chain, which
further acts as a glue to link the adjacent chains into 2D supramo-
lecular hydrogen-bonded layer (Fig. 1C and Table 3). It is worthy to
note that both O4W and O5W are disordered over two positions.
The 2D hydrogen-bonded supramolecular layers are further hal-
ogen-bonded to each other, which is verified by the C–IÁ Á ÁN dis-
tance of 3.292 Å. Thus, 3D supramolecular MOF with 1D channels

52
K.-L. Zhang et al. / Inorganica Chimica Acta 368 (2011) 49–57
Fig. 1 (continued)
is formed. So, the C–IÁ Á ÁN halogen bonding plays a significant role
The nearest two Zn(II)-btb-bridged chains are further connected
by the bridging ATIBDC2À ligands in (k1)–(k1)-
2 coordination mode
in the 3D supramolecular assembly (Fig. 1D and E).
l
to generate a single-walled tube-like 21 helical chain (Scheme 2).
The ZnÁ Á ÁZn separation by ATIBDC2À bridge is 7.1579(14) Å
3.3. Structure description of [Zn(ATIBDC)(btb)]Á2H2O (2)
(Fig. 2B–D). Within the helical tube-like chain, there are
pÁ Á Áp
stacking interactions between the imidazole ring N4N5N6C15C16
of btb and benzene ring of the ATIBDC2À ligand as evidenced by
the centeroidÁ Á Ácenteroid distance of 3.6019(5) Å. There are no
residual solvent-accessible void in the ‘‘tube’’ calculated by PLATON
[22].
It should be interesting to note that the halogen bonding C8–
I1Á Á ÁN5 [3.1862(75) Å] also exists within the tube-like chain
Complex 2 also crystallizes in monoclinic space group P21/n.
Quite different from the structure of 1, complex 2 has a novel sin-
gle-walled tube-like chain structure. The asymmetric unit of 2 con-
tains one zinc ion, one ATIBDC2À ligand, one btb ligand, and two
uncoordinated H2O molecules. As shown in Fig. 2A, the central zinc
ion is four-coordinated by two oxygen atoms from two different
ATIBDC2À ligands and two triazole nitrogen atoms from two differ-
ent btb ligands in a distorted tetrahedral geometry with the aver-
age Zn–O and Zn–N distances of 1.952 and 2.008 Å, respectively
(Table 2). The btb molecule acts as a bidentate bridging ligand,
linking the Zn(II) ions into a btb-bridged chain with the nearest
intrachain ZnÁ Á ÁZn distance of 10.1159(20) Å. The btb ligand shows
the gauche–gauche–trans conformation in complex 2 (Scheme 1).
(Fig. 2C). It is really fascinating that the halogen bonding,
p p
Á Á Á
stacking interactions as well as the tetrahedral configuration of
Zn(II) ion act as the directing forces of the tube-like chain.
Although various MOFs with tubular channels have been synthe-
sized, it is difficult to prepare isolated coordination tubes owing
to the interlocks or interpenetration [23–25]. Only a few isolated
coordination tubes have been reported to date [26–34]. The work

K.-L. Zhang et al. / Inorganica Chimica Acta 368 (2011) 49–57
53
NH2
Table 2
NH2
Selcted bond lengths (Å) and angles (°) for the complexes.
I
I
I
I
Complex 1
Cd(1)–N(2)
2.250(4)
2.277(3)
2.342(3)
2.388(3)
Cd(1)–O(2W)
Cd(1)–O(2)
Cd(1)–O(1)
2.406(3)
2.438(3)
2.612(4)
Cd(1)–N(7)#1
Cd(1)–O(1W)
Cd(1)–O(3)#1
O
M
O
O
M
O
M
C
O
C
C
O
C
M
I
I
O
N(2)–Cd(1)–N(7)#1
N(2)–Cd(1)–O(1W)
N(7)#1–Cd(1)–O(1W)
N(2)–Cd(1)–O(3)#1
N(7)#1–Cd(1)–O(3)#1
O(1W)–Cd(1)–O(3)#1
N(2)–Cd(1)–O(2W)
N(7)#1–Cd(1)–O(2W)
O(1W)–Cd(1)–O(2W)
O(3)#1–Cd(1)–O(2W)
N(2)–Cd(1)–O(2)
168.71(13)
100.83(14)
85.83(13)
84.65(11)
87.26(11)
82.24(10)
87.64(14)
82.87(13)
156.79(12)
77.04(11)
96.32(12)
N(7)#1–Cd(1)–O(2)
O(1W)–Cd(1)–O(2)
O(3)#1–Cd(1)–O(2)
O(2W)–Cd(1)–O(2)
N(2)–Cd(1)–O(1)
N(7)#1–Cd(1)–O(1)
O(1W)–Cd(1)–O(1)
O(3)#1–Cd(1)–O(1)
O(2W)–Cd(1)–O(1)
O(2)–Cd(1)–O(1)
87.63(12)
122.19(11)
154.56(11)
77.60(12)
82.36(13)
108.17(12)
77.17(11)
153.04(11)
125.69(12)
51.05(11)
O
(k1)-(k1)-u2-ATIBDC2-
(k2)-(k1)-u2-ATIBDC2-
2
1
Scheme 2. Schematic representation of the coordination modes of the ATIBDC2À
ligand in 1–2.
Table 3
The details of the hydrogen bonds for the title complexes.
Complex 2
Zn(1)–N(1)
Zn(1)–O(1)
D–HÁ Á ÁA
d(D–H) d(HÁ Á ÁA) d(DÁ Á ÁA)
<DHA
Symmetry
of A
2.017(6)
1.941(5)
Zn(1)–O(3)#3
Zn(1)–N(6)#4
1.963(4)
1.999(6)
Complex 1
O(1)–Zn(1)–O(3)#3
O(1)–Zn(1)–N(6)#4
O(3)#3–Zn(1)–N(6)#4
106.9(2)
115.6(2)
113.2(2)
O(1)–Zn(1)–N(1)
O(3)#3–Zn(1)–N(1)
N(6)#4–Zn(1)–N(1)
115.2(2)
99.7(2)
105.2(2)
N1–H1N1Á Á ÁI3
N1–H1N2Á Á ÁI2
N1–H1N2Á Á ÁO3W
0.8600 2.7200
0.8600 2.7100
0.8600 2.4200
3.196(4)
3.191(4)
3.125(5)
117.00
117.00
140.00 1/2 + x,
3/2 À y,
Symmetry transformations used to generate equivalent atoms: (#1) Àx + 3/2, y + 1/
2, Àz + 3/2 for 1; (#3) Àx + 1, Ày + 1, z À 1/2; (#4) x, y, z À 1 for 2.
1/2 + z
O1W–H1W1Á Á ÁO3W 0.8500 2.0500
O2W–H2W1Á Á ÁO4W 0.8500 2.0900
O2W–H2W2Á Á ÁO3W 0.8500 2.1900
2.869(5)
2.905(7)
2.937(5)
2.814(5)
2.770(7)
162.00 1 + x, y, z
162.00 x, 1 + y, z
147.00
157.00
179.00 1/2 À x,
O3W–H3W2Á Á ÁO2
0.8600 2.0000
presented here reports a convenient one-pot synthesis of a new
isolated infinite tube-like single-walled chain by using two kinds
of bidentate ligands, which may provide an efficient way to synthe-
size isolated tube.
Both the lattice water molecules O1W and O2W act as double
hydrogen bond donor (Table 3). The interchain hydrogen bonds
[O1W–H1WAÁ Á ÁO4 2.790(9), O1W–H1WBÁ Á ÁN2 3.010(11), O2W–
H2WAÁ Á ÁO2 2.891(7), O2W–H2WBÁ Á ÁO3 3.007(8) Å] further ex-
tends single-walled tube-like chain into 3D supramolecular net-
work (Fig. 2E).
O3W–H3W1Á Á ÁO5W 0.8500 1.9200
1/2 + y,
3/2 À z
C15–H15Á Á ÁO2W
0.9300 2.5800
3.114(6)
117.00 3/2 À x,
À1/2 + y,
3/2 À z
Complex 2
O1W–H1WAÁ Á ÁO4
0.8600 1.9400
0.8600 2.3600
2.790(9)
174.00 1 À x, 1 À y,
1/2 + z
O1W–H1WBÁ Á ÁN2
3.010(11) 133.00 1/2 À x,
À1/2 + y,
1/2 + z
O2W–H2WAÁ Á ÁO2
0.8500 2.2600
2.891(7)
131.00 3/2Àx,
À1/2 + y,
1/2 + z
3.4. Discussion of the structures
O2W–H2WBÁ Á ÁO3
O2W–H2WBÁ Á ÁO4
N7–H7AÁ Á ÁI2
0.8500 2.4500
0.8500 2.3800
0.8600 2.7400
0.8600 2.3600
0.8600 2.7300
0.9300 2.4200
3.007(8)
3.220(8)
3.211(6)
3.078(9)
3.217(7)
3.265(8)
124.00
174.00
116.00
From the above-mentioned structural descriptions, it can be
seen that the metal centers have great influence on the crystalline
architectures of these two compounds. Both Zn(II) and Cd(II) have
no crystal field stabilization energy due to their closed d10 elec-
tronic shells when their complexes are formed. The coordination
numbers of Zn(II) and Cd(II) are mainly determined by the steric
repulsion between different ligands. Since the radius of Cd(II) is
larger than that of Zn(II), the coordination number of Cd(II) in 1
is seven, which is larger than that of Zn(II) in 2 (four). Thus, the
structural discrepancies between 1 and 2 may mainly be attributed
to the differences in the coordination numbers of Zn(II) and Cd(II)
because the auxiliary ligand in these two complexes is the same
N7–H7AÁ Á ÁO2W
N7–H7BÁ Á ÁI3
141.00 x, y, À1 + z
117.00
C9–H9Á Á ÁO2W
151.00 1 À x, 1 À y,
À1/2 + z
C10–H10Á Á ÁO2
0.9300 2.5200
0.9300 2.4500
3.178(8)
3.189(12) 136.00 1/2 + x,
3/2 À y, z
128.00
C15–H15Á Á ÁO1W
(btb). So, the coordination behavior of the metal nodes plays a sig-
nificant role in the case.
Scheme 1. The conformations of the auxiliary ligand, btb, in complexes 1–2.

54
K.-L. Zhang et al. / Inorganica Chimica Acta 368 (2011) 49–57
Fig. 2. (A) The coordination environment of Zn(II) and the conformation of btb in 2. (B) Side view of 1D helical chain, where the dashed red and green lines represent
pÁ Á Áp
stacking interactions and the halogen bonding (C8–I1Á Á ÁN5), respectively. (C) Schematic view of the 1D helical tube-like chain. The solid yellow line represents 21 helice. (D)
Top view of 1D helical chain. (E) 3D supramolecular MOF formed by interchain hydrogen bonding (yellow dashed lines). (For interpretation of the references to color in this
figure legend, the reader is referred to the web version of this article.)
3.5. FT-IR spectra and thermal stability
in the range of 1680–1760 cmÀ1 indicates the complete deprotona-
tion of H2ATIBDC in the two complexes. The characteristic bands of
the carboxylate groups appear in the range 1552–1598 cmÀ1 for
the asymmetric stretching and 1384–1490 cmÀ1 for the symmetric
The FT-IR spectral data show features attributable to the car-
boxylate stretching vibrations of 1 and 2A. The absence of bands

K.-L. Zhang et al. / Inorganica Chimica Acta 368 (2011) 49–57
55
Fig. 2 (continued)
stretching. The broad band at ca. 3300 cmÀ1 corresponds to the
vibration of the –NH2 group in the ATIBDC2À ligand, and water
molecules in the corresponding complexes 1 and 2A [35].
X-ray powder diffraction measurement further shows that the
structure of 2A is slightly different from that of 2 (Fig. 4).
To study the thermal stability of the compounds, the thermo-
gravimetric analysis (TGA) was performed on all samples under a
3.6. Fluorescent properties
nitrogen atmosphere in flowing N2 with
a heating rate of
The solid state fluorescent properties of the polymeric Zn(II)
and Cd(II) complexes have been investigated at room temperature.
To well-compare the fluorescent intensity of these compounds, we
determined all the emission spectra with the same excitation
wavelength. Excitation of the complexes at 290 nm leads to the
generation of similar fluorescent emissions in 1 and 2A (Fig. 5),
with the same peaks occurring at 473 and 453 nm, although the
intensities are different. To further understand the origin of these
emission bands, the fluorescent spectrum of H2ATIBDC has also
been measured. The free H2ATIBDC acid exhibits the nearly same
emission (kex = 290 nm) peaks as those in 1 and 2A. These observa-
10 °C minÀ1 (Fig. 3). Complex 1 exhibits a weight loss of 10.31%
in the temperature range 30–140 °C, corresponding to the removal
of both the coordinated and lattice water molecules (Calc. 9.64%).
The second step begins at 248 °C and then followed by a long tail.
The weight loss of 1.96% from 85 to 148 °C corresponds to the
release of one lattice water molecule, which further reveals that
[Zn(ATIBDC)(btb)]Á2H2O (2) loses one lattice water molecule rap-
idly in the open air and changes into [Zn(ATIBDC)(btb)]ÁH2O (2A)
(Calc. 2.16%). The second step begins from 295 °C and the whole
decomposition process does not finish at 800 °C.

56
K.-L. Zhang et al. / Inorganica Chimica Acta 368 (2011) 49–57
tions suggest that the coordination of the ATIBDC2À ligand with
Zn(II) and Cd(II) ions in the presence of btb auxiliary ligand has
no influence on the emission mechanism of the metal–organic
coordination polymers [36]. So, the emissions of the complexes 1
100
80
60
40
20
0
and 2A may be assigned to an intraligand
p
Á Á Á Ã transition [37].
p
The small differences of the peak intensities in 1 and 2A are consid-
ered to be a result of the dissimilar coordination environments of
the metal centers with the incorporation of co-ligands, which
may also participate in the process of energy transfer involved in
the fluorescence.
4. Conclusion
In summary, two d10 metal–organic supramolecular complexes
1–2 with the ATIBDC2À ligand have been prepared and structurally
characterized. These two complexes showed polymeric chain
structures and possess extended 3D supramolecular architectures
with the aid of supramolecular driving forces. The features of the
ATIBDC2À ligand, strong ability of hydrogen/halogen bonding, have
been embodied in these two complexes. Complex 2 gives an inter-
esting example of an infinite single-walled tube-like chain con-
structed by using two kinds of polydentate ligands. The
interesting characteristic embodied in 2 may provide a new means
of constructing discrete 1D single-walled coordination tube
through combination of appropriate polydentate ligands and metal
ions. Three I atoms in H2ATIBDC play important roles in construct-
ing the supramolecular architectures of 1–2. The studies further re-
0
100
200
300
400
500
600
700
800
900
Temperature / 0
C
Fig. 3. The TG curves of complexes 1 (black) and 2 (red). (For interpretation of the
references to colour in this figure legend, the reader is referred to the web version of
this article.)
veal that the halogen bonds (C–IÁ Á Á and C–IÁ Á ÁO/N) are useful tools
p
to construct supramolecular networks. The use of halogen bonding
as supramolecular driving force opens up new insights to supra-
molecular synthesis. Initially, it is likely that the interest can be
stimulated to develop a novel family of iodine-substituted aro-
matic polycarboxylate ligands as supporting spacers. Further syn-
thesis of the related supramolecular complexes with the series of
I-substituted aromatic polycarboxylate ligands are underway.
Acknowledgments
10
20
30
40
50
2θ /degree
The authors gratefully acknowledge the financial support of
Yangzhou University and Key Laboratory of Environmental Mate-
rial and Environmental Engineering of Jiangsu Province for the
financial support of this work.
Fig. 4. PXRD patterns of 2 (black) simulated from the single-crystal data, (red) for
the powder sample 2A. (For interpretation of the references to colour in this figure
legend, the reader is referred to the web version of this article.)
Appendix A. Supplementary material
CCDC 743506 and 740001 for (1) and (2), respectively, contains
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.ica.2010.12.038.
240
220
200
180
160
140
120
100
80
References
[1] J. An, S.J. Geib, N.L. Rosi, J. Am. Chem. Soc. 132 (2010) 38.
[2] B.H. Ye, M.L. Tong, X.M. Chen, Coord. Chem. Rev. 249 (2005) 545.
[3] R. Matsuda, R. Kitaura, S. Kitagawa, Y. Kubota, R.V. Belosludov, T.C. Kobayashi,
H. Sakamoto, T. Chiba, M. Takata, Y. Kawazoe, Y. Mita, Nature 436 (2005) 238.
[4] P.L. Llewellyn, P. Horcajada, G. Maurin, T. Devic, N. Rosenbach, S. Bourrelly, C.
Serre, D. Vincent, S. Loera-Serna, Y. Filinchuk, G. Férey, J. Am. Chem. Soc. 131
(2009) 13002.
60
40
350
400
450
500
550
600
[5] J.M. Lehn, Supramolecular Chemistry: Concepts and Perspectives, VCH, New
York, 1995.
Wavelength (nm)
[6] A.G. Wong-Foy, A.J. Matzger, O.M. Yaghi, J. Am. Chem. Soc. 128 (2006) 3494.
[7] J. Lee, O.K. Farha, J. Roberts, K.A. Scheidt, S.T. Nguyen, J.T. Hupp, Chem. Soc. Rev.
38 (2009) 1450.
[8] W.J. Rieter, K.M. Pott, K.M.L. Taylor, W. Lin, J. Am. Chem. Soc. 130 (2008) 11584.
[9] Y.Y. Niu, H.G. Zheng, H.W. Hou, X.Q. Xin, Coord. Chem. Rev. 248 (2004) 169.
Fig. 5. The emission spectra of H2ATIBDC (black), 1 (red), 2 (green) in the solid state
at 298 K. The corresponding excitation wavelengths, kex, is 290 nm. (For interpre-
tation of the references to colour in this figure legend, the reader is referred to the
web version of this article.)

K.-L. Zhang et al. / Inorganica Chimica Acta 368 (2011) 49–57
57
[10] X.H. Bu, W. Chen, S.L. Lu, R.H. Zhang, D.Z. Liao, W.M. Shionoya, M. Bu, F. Brisse,
J. Ribas, Angew. Chem., Int. Ed. 40 (2001) 3201.
[11] X.-H. Zhou, Y.-H. Peng, X.-D. Du, C.-F. Wang, J.-L. Zuo, X.-Z. You, Cryst. Growth
Des. 9 (2009) 1028.
[25] P. Jensen, S.R. Batten, B. Moubaraki, K.S. Murray, Chem. Commun. (2000) 793.
[26] M. Aoyagi, K. Biradha, M. Fujita, J. Am. Chem. Soc. 121 (1999) 7457.
[27] T. Yamaguchi, S. Tashiro, M. Tominaga, M. Kawano, T. Ozeki, M. Fujita, J. Am.
Chem. Soc. 126 (2004) 10818.
[12] J. Yang, J.-F. Ma, Y.-Y. Liu, J.-C. Ma, S.R. Batten, Inorg. Chem. 46 (2007) 6542.
[13] A.M. Beatty, Coord. Chem. Rev. 246 (2003) 131.
[28] S. Tashiro, M. Tominaga, T. Kusukawa, M. Kawano, S. Sakamoto, K. Yamaguchi,
M. Fujita, Angew. Chem., Int. Ed. 42 (2003) 3267.
[14] X.-P. Li, J.-Y. Zhang, M. Pan, S.-R. Zheng, Y. Liu, C.-Y. Su, Inorg. Chem. 46 (2007)
4617.
[15] D.F. Sava, V.Ch. Kravtsov, J. Eckert, J.F. Eubank, F. Nouar, M. Eddaoudi, J. Am.
Chem. Soc. 131 (2009) 10394.
[16] F. Dai, H. He, D. Gao, F. Ye, X. Qiu, D. Sun, CrystEngComm 11 (2009) 2516.
[17] F. Dai, H. He, D. Sun, J. Am. Chem. Soc. 130 (2008) 14064.
[18] F. Dai, H. He, D. Sun, Inorg. Chem. 48 (2009) 4613.
[19] K.-L. Zhang, Y. Chang, C.-T. Hou, G.-W. Diao, R. Wu, S.W. Ng, CrystEngComm 12
(2010) 1194.
[29] C.Y. Su, M.D. Smith, H. Loye, Angew. Chem., Int. Ed. 42 (2003) 4085.
[30] F. Chang, Z.M. Wang, H.L. Sun, S. Gao, G.H. Wen, X.X. Zhang, J. Chem. Soc.,
Dalton Trans. 18 (2005) 2976.
[31] J. Fan, H.F. Zhu, T.A. Okamura, W.Y. Sun, W.X. Tang, N. Ueyama, Inorg. Chem. 42
(2003) 158.
[32] A.M. Madalan, C. Paraschiv, J.P. Sutter, M. Schmidtmann, A. Müller, M. Andruh,
Cryst. Growth Des. 5 (2005) 707.
[33] Y.B. Dong, Y.Y. Jiang, J. Li, J.P. Ma, F.L. Liu, J. Am. Chem. Soc. 129 (2007)
4520.
[20] X. Liu, Y. Zhang, B. Li, J. Suzhou Univ. (Nat. Sci.) 121 (2005) 59.
[21] G.M. Sheldrick, SHELXL 97. Programs for Crystal Structure Analysis (Release
97-2), University of Götinggen, Germany, 1997.
[22] A.L. Spek, PLATON, A Multipurpose Crystallographic Tool, Utrecht University,
Utrecht, The Netherlands, 2002.
[23] X.L. Wang, C. Qin, E.B. Wang, L. Xu, Z.M. Su, C.W. Hu, Angew. Chem., Int. Ed. 43
(2004) 5036.
[24] M.C. Hong, Y.J. Zhao, W.P. Su, Angew. Chem., Int. Ed. 39 (2000) 2468.
[34] H.T. Zhang, Y.Z. Li, T.W. Wang, H.Q. Wang, X.Z. You, Eur. J. Inorg. Chem. (2006)
3532.
[35] K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination
Compounds, fourth ed., Wiley, New York, 1986. p. 231.
[36] S.T. Wang, Y. Hou, E.B. Wang, Y.G. Li, L. Xu, J. Peng, S.X. Liu, C.W. Hu, New J.
Chem. 27 (2003) 1144.
[37] S.J.A. Pope, B.J. Coe, S. Faulkner, E.V. Bichenkova, X. Yu, K.T. Douglas, J. Am.
Chem. Soc. 126 (2004) 9490.