Syntheses, structures, and supra-molecular assembles of zinc 4-sulfobenzoate complexes with chelating and/or bridging ligands

Article abstract of DOI:10.1016/j.molstruc.2009.05.032

Three unique Zn^II/4-sulfobenzoate complexes based on 2,2′-bipyridine and/or 4,4′-bipyridine, [Zn(4-sb)(2,2′-bipy)(H₂O)₃]·H₂O (1), {[Zn(4,4′-bipy)(H₂O)₄]·(4-sb)}_n (2), and {[Zn(4-

Full text of DOI:10.1016/j.molstruc.2009.05.032

Journal of Molecular Structure 931 (2009) 87–93
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Syntheses, structures, and supra-molecular assembles of zinc 4-sulfobenzoate
complexes with chelating and/or bridging ligands
*
Jing Zhang, Long-Guan Zhu
Department of Chemistry, Zhejiang University, Hangzhou 310027, People’s Republic of China
a r t i c l e i n f o
a b s t r a c t
Three unique ZnII/4-sulfobenzoate complexes based on 2,20-bipyridine and/or 4,40-bipyridine, [Zn(4-
sb)(2,20-bipy)(H2O)3]ꢀH2O (1), {[Zn(4,40-bipy)(H2O)4]ꢀ(4-sb)}n (2), and {[Zn(4-sb)(2,20-bipy)(4,40-bipy)0.5(-
H2O)]ꢀ2H2O}n (3) [4-sb = 4-sulfobenzoate; 4,40-bipy = 4,40-bipyridine; 2,20-bipy = 2,20-bipyridine], have
been prepared and characterized by single-crystal X-ray analyses, elemental analyses, IR, thermogravi-
metric analyses and fluorescent spectra. The molecular structure of the complex 1 is a monomer species,
while the structures of complexes 2 and 3 are 1-D chains. The complex 2 is a cation–anion species. These
extended hydrogen-bonding networks are 3-D architectures. In complexes 1 and 3 there are strong p. . .p
stacking effects, while in complex 2 there is no such interaction. The thermal stability of complexes 1, 2,
and 3 has the order of 2 > 1 > 3.
Article history:
Received 21 April 2009
Received in revised form 12 May 2009
Accepted 15 May 2009
Available online 21 May 2009
Keywords:
Synthesis
Crystal structure
Fluorescence
Supra-molecular assembly
Diverse structure
Sulfobenzoate
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
{[Zn(4,40-bipy)(H2O)4](4-sb)}n (2), and [Zn(4-sb)(2,20-bipy)(4,40-
bipy)0.5(H2O)]nꢀ2H2O (3).
In recent years, diverse metal complexeshave attracted consider-
able attention due to their potential functional applications strongly
related to their structures [1–4]. Many factors can influence the syn-
thesis of diverse metal complexes, such as metal ions, coordination
features of the ligands, starting materials, pH, temperature, syn-
thetic methods, and templates [5–10]. Diverse structures, in general,
show different supra-molecular building blocks, different hydro-
gen-bonding patterns, and different weak interactions, therefore
careful tune of the diverse structures will construct specific func-
tional materials [11,12]. The 4-sulfobenzoate ligand with two differ-
ent functional groups have been used to produce several interesting
metal complexes in our lab and our results showed that this ligand
performs abundant bonding modes, coordination sites and bonding
directions [13–19]; therefore the 4-sulfobenzoate is a good candi-
date for constructing diverse metal complexes. On the other hands,
the coordination modes of 4-sulfobenzoate ligand with metal ions
can be adjusted by the addition of the neutral ligands; such effect
further results in abundant diverse structures. For the reasons above
mentioned, we choose 4-sulfobenzoate ligand with fixed metal ion,
zinc, but used the combination of 2,20-bipyridine and/or 4,40-bipyr-
idine to synthesize novel diverse complexes. Herein, we report syn-
theses, structures, properties, and supra-molecular assembles of
three new complexes, namely, [Zn(4-sb)(2,20-bipy)(H2O)3]ꢀH2O (1),
2. Experimental
2.1. Materials and physical measurements
Chemicals and solvents used in the experiments were obtained
from commercial sources and were used as received without puri-
fication. C, H, and N elemental analyses were carried out on a Per-
kin–Elmer analyzer model 1110. The IR spectra were taken on a
Nicolet Nexus 470 IR spectrophotometer as KBr pellets in the
400–4000 cmꢁ1 region. Thermogravimetric analyses (TGA) were
studied by a Delta Series TA-SDT Q600 in a N2 atmosphere in the
temperature range between room temperature and 800 °C at a
heating rate of 10 °C minꢁ1 using Al2O3 crucibles. The fluorescent
study was carried out on a powdered sample in the solid state at
room temperature using a Hitachi 850 spectrometer.
2.2. Synthesis of [Zn(4-sb)(2,20-bipy)(H2O)3]ꢀH2O (1)
A mixture of Zn(CH3COO)2 ꢀ 2H2O (0.112 g, 0.5 mmol), 4-sulfo-
benzoic acid mono-potassium salt (0.120 g, 0.5 mmol), 2,20-bipyri-
dine (0.078 g, 0.5 mmol) and 15 ml H2O was placed in a 30 ml
Teflon-lined stainless-steel and heated at 433 K for 3 days. The ves-
sel was slowly cooled to room temperature, and then filtered and
the filtrate was standing for 15 days and colorless brick crystals
of 1 were obtained. Yield: 24% based on zinc salt. Anal. Calcd. for
* Corresponding author. Tel.: +86 571 87963867; fax: +86 571 87951895.
E-mail address: chezlg@zju.edu.cn (L.-G. Zhu).
0022-2860/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2009.05.032

88
J. Zhang, L.-G. Zhu / Journal of Molecular Structure 931 (2009) 87–93
C17H20 N2O9ZnS: C, 41.35%; H, 4.08%; N, 5.67%; found: C, 41.42%; H,
4.10%; N, 5.58%. IR (KBr pellet, cmꢁ1): 3377(s), 1599(s), 1552(m),
1493(w), 1476(w), 1444(s), 1401(s), 1317(w), 1220(s), 1186(s),
1010(s), 868(w), 767(s), 736(s), 702(m), 643(m), 565(m).
matized Mo Ka radiation (k = 0.71073 Å). The data were integrated
by use of the SAINT program [20] and this program also did the
intensities corrected for Lorentz and polarization effects. The
absorption corrections were done by the SADABS program [21].
All of these three structures were solved initially by direct methods
and then completed by full matrix least squares on F2 followed by
difference Fourier synthesis using the SHELXL-97 program [22] in
the WinGX environment [23]. In all three structures, the non-
hydrogen atoms were refined with anisotropic displacement
parameters. The O5 atom is disordered over two positions with
the ratio of 0.51(7): 0.49(7) in complex 1. Hydrogen atoms bonded
to the carbon atoms were placed in calculated positions and re-
fined as riding, with C–H = 0.93 Å and Uiso(H) = 1.2Ueq(C). The
water hydrogen atoms were located in the difference Fourier maps
and refined with an O–H distance restraint of 0.85(1) Å. The draw-
ings of the three molecules were realized with the help of ORTEP-3
for Windows [24] and Mercury software [25]. Crystallographic data
and refinement parameters for these three complexes are given in
Table 1.
2.3. Synthesis of {[Zn(4,40-bipy)(H2O)4]ꢀ(4-sb)}n (2)
A mixture of Zn(CH3COO)2ꢀ2H2O (0.112 g, 0.5 mmol), 4-sulfo-
benzoic acid mono-potassium salt (0.120 g, 0.5 mmol), 4,40-bipyri-
dine (0.078 g, 0.5 mmol) and 15 ml H2O was placed in a 30 ml
Teflon-lined stainless-steel and heated at 433 K for 3 days. The ves-
sel was slowly cooled to room temperature, and then filtered and
the filtrate was standing for 2 days. Colorless crystal of 2 was ob-
tained. Yield: 37% based on zinc salt. Anal. Calcd. for C17H20
N2O9ZnS: C, 41.35%; H, 4.08%; N, 5.67%; found: C, 41.33%; H,
4.08%; N, 5.62%. IR (KBr pellet, cmꢁ1): 3301(s), 1613(s), 1545(m),
1498(w), 1421(m), 1377(s), 1228(s), 1176(s), 1115(s), 1034(s),
1010(s), 883(w), 820(m), 795(m), 734(s), 706(w), 636(s), 571(w).
2.4. Synthesis of [Zn(4-sb)(2,20-bipy)(4,40-bipy)0.5(H2O)]n ꢀ 2H2O (3)
3. Results and discussion
A mixture of Zn(CH3COO)2ꢀ2H2O (0.112 g, 0.5 mmol), 4-sulfo-
benzoic acid mono-potassium salt (0.120 g, 0.5 mmol), 2,20-bipyri-
dine (0.078 g, 0.5 mmol), 4,40-bipyridine (0.078 g, 0.5 mmol) and
15 ml H2O was placed in a 30 ml Teflon-lined stainless-steel and
heated at 433 K for 3 days. After cooled to room temperature, col-
orless block crystal was obtained from the vessel. Yield: 45% based
on zinc salt. Anal. Calcd. for C22H22N3SZnO8: C, 47.71%; H, 4.00%; N,
7.59%; found: C, 47.78%; H, 4.23%; N, 7.33%. IR (KBr pellet, cmꢁ1):
3427(s), 1609(s), 1551(s), 1491(m), 1478(m), 1446(m), 1403(s),
1320(w), 1229(s), 1183(s), 1162(s), 1143(m), 1119(s), 1071(w),
1036(s), 1024(m), 1008(s), 810(m), 779(s), 766(s), 737(s),
698(m), 642(m), 632(m), 568(w).
3.1. Synthesis
In our lab, we have synthesized the complex [Zn(4,40-
bipy)2(H2O)4]ꢀ2(4-Hsb) (4), in which the 4-sulfobenzoate is partly
deprotonated and exists as a non-coordinating anion [17]. Our tar-
get was to obtain the full deprotonation 4-sb, therefore the further
exploration was done. The synthesis of complex 4 was achieved by
using the starting material ZnSO4ꢀ7H2O. The Zn(CH3COO)2ꢀ2H2O
used in the new procedure led to the precipitation of complex 2.
In complex 2, although the 4-sb is fully deprotonated, it is still a
non-coordinating anion. Considering the coordination behavior of
4-sb in 2,20-bipyridine zinc complex, 1, we combined the 2,20-bipy
and 4,40-bipy to synthesize novel complex with the coordination of
4-sb to the metal ion. The hydrothermal synthesis led to novel
complex, 3, in which the complex contains both chelating and
bridging ligands.
2.5. Single-crystal structure determination
Crystals with suitable sizes of 1–3 were selected for data collec-
tion by a Bruker Smart CCD area detector with graphite monochro-
Table 1
Crystallographic data and refinement parameter for complexes 1, 2, and 3.
Complex
1
2
3
Empirical formula
Formula
C17H20 N2O9SZn
493.78
C17H20 N2O9SZn
493.78
C22H22N3O8SZn
553.86
Crystal color/shape
Crystal size/mm
Space group
a (Å)
b (Å)
c (Å)
Colorless/brick
0.31 ꢂ 0.24ꢂ0.22
Monoclinic, P21/n
11.7796(10)
11.2355(9)
16.3836(13)
90
104.398(1)
90
2100.3(3)
4
Colorless/block
0.37 ꢂ 0.28 ꢂ 0.23
Colorless/block
0.33 ꢂ 0.21 ꢂ 0.19
ꢀ
ꢀ
Triclinic, P1
Triclinic, P1
7.3840(7)
10.5394(9)
13.5034(12)
67.387(1)
83.674(1)
78.483(1)
949.91(15)
2
8.8716(25)
9.8863(28)
13.5952(36)
86.793(8)
89.864(8)
79.971(8)
1172.3(6)
2
a
(°)
b (°)
c
(°)
V (Å3)
Z
D (g cmꢁ3
T (K)
l
)
1.562
295(2)
1.320
1.726
295(2)
1.459
1.569
295(2)
1.190
(mmꢁ1
)
h range (°)
2.2–27.5
12842
4804
3908
1016
2.1–25.3
5037
3382
3096
508
1.5–25.0
9711
3755
2806
570
Measured reflections
Unique reflections
Observed reflections
F (0 0 0)
R1 and wR2 (I > 2
R1 and wR2 (all data)
Number of variable
r
(I))
0.030, 0.084
0.041, 0.093
306
0.024, 0.071
0.027, 0.075
295
0.048, 0.152
0.073, 0.212
334
Goodness of fit (GOF)
0.811
0.345, ꢁ0.379
0.842
0.344, ꢁ0.355
1.262
0.642, ꢁ0.784
Largest difference peak and hole (e Åꢁ3
)

J. Zhang, L.-G. Zhu / Journal of Molecular Structure 931 (2009) 87–93
89
Fig. 1. ORTEP view of the molecular structure of complex 1. Hydrogen atoms are omitted for clarity.
3.2. Description of the molecular structures
2, the 4-sb in 3 bis-monodentately acts as a bridge by two O atoms
from carboxyl group and sulfonate group and the 4,40-bipyridine is
only a dimeric ligand linking ZnII ions. The bond lengths of Zn–
The molecular structure of complex 1 is a monomer (Fig. 1 and
Table 2), while complexes 2 and 3 are 1-D chains (Figs. 2 and 3; Ta-
bles 3 and 4). In these three complexes, zinc ions adopt octahedron
geometries. The zinc coordination geometry in 1 is completed by
two N atoms of one 2,20-bipyridne, one O atom from the 4-sb,
and three O atoms from three water molecules. The Zn–O bond dis-
tances in 1 range from 2.0716(15) Å to 2.1474(15) Å. The Zn–N
bond lengths are in agreement with those of Zn(II) complexes con-
taining 2,20-bipyridine [26,27].
The complex 2 is a cation–anion species (Fig. 2a). The cationic
motif (Fig. 2b), [Zn(4,40-bipy)(H2O)4]2+, is a 1-D chain in which the
4,40-bipyridine is a polymeric bridging ligand and such motif has
been reported by others [28]. The separation distance of Zn. . .Zn be-
tween 1-D chains is 7.0275(6) Å. The pyridyl rings of the 4,40-bipyr-
idine ligands are not coplanar with a dihedral angle of 12.7(1)°. The
4-sb in complex 2 is fully deprotonated but uncoordinated and only
serves as a counter-ion. The bond lengths of Zn–O range from
2.0977(14) Å to 2.1875(15) Å which are compared well with those
distances reported for other ZnII-aqua (2.12–2.19 Å) complexes
[28–30]. The bond distances of Zn–N are typical for ZnII compounds
with 4,40-bipyridine [31,32]. The separation of Zn. . .Zn by 4,40-bipyr-
idine ligand in the cationic chain is 11.3649 (8) Å which is shorter
than those of previous reports [28].
0
N2,2 -bipy are a little bit longer than that in complex 1 and bond
0
lengths of Zn–N4,4 -bipy are longer than that in complex 2. The bond
lengths of Zn–O are consistent with other two complexes, 1 and 2.
The distances of Zn. . .Zn separated by 4-sb and 4,40-bipyridine are
9.539(2) Å and 11.433(2) Å (longer than that in complex 1),
respectively.
The addition of neutral ligands in ZnII/4-sb system leads to dif-
ferent supra-molecular assembles. All 4-sb ligands in these three
complexes are fully deprotonated and perform three different
coordination modes, monodentate in 1, free ligand in 2, and bis-
monodentate in 3. The 4,40-bipy ligands in 2 act as polymeric link-
ers while in complex 3 the 4,40-bipy ligand serves as a dimeric
bridge. And in complex 4, [Zn(4,40-bipy)2(H2O)4]ꢀ2(4-Hsb), the
4,40-bipy is only a monodentate terminal ligand. Therefore, careful
control or tune of synthetic procedures results in abundant diverse
metal complexes.
3.3. Hydrogen bonds and p–p stacking interactions
In complex 1, there is one intra-molecular hydrogen bond be-
tween coordinated water molecule and carboxyl group. There are
abundant inter-molecular O–Hꢀ ꢀ ꢀO hydrogen bonds between coor-
dinated water molecules and carboxyl groups, sulfonate groups,
and lattice water molecules, respectively, and between sulfonate
groups and lattice water molecules. These hydrogen-bonding
interactions extend the monomer structure into 3-D architecture
The X-ray single-crystal analysis reveals complex 3 is a zig-zag
chain linked by 4-sb and 4,40-bipy (Fig. 3a). Unlike complexes 1 and
(Fig. 4). Within the 3-D framework, face to face
p–p interactions
Table 2
occur between rings of symmetry-related 2,20-bipyridine ligands
with a centroid-to-centroid distance of 3.7721(15) Å and between
2,20-bipy (the ring of N1/C1–C5) and 4-sb (the ring of C12–C17)
with a centroid-to-centroid distance of 3.6845(13) Å. The existence
Selected bond lengths (Å) and angles (°) in complex 1.
Zn1–O2
Zn1–O7
Zn1–N1
2.0730(14)
2.1474(15)
2.1273(17)
90.76(5)
94.03(7)
169.44(7)
89.21(6)
89.51(6)
91.21(6)
173.08(7)
77.24(7)
Zn1–O6
Zn1–O8
Zn1–N2
O2–Zn1–O7
O2–Zn1–N1
O6–Zn1–O7
O6–Zn1–N1
O7–Zn1–O8
O7–Zn1–N2
O8–Zn1–N2
2.1394(15)
2.0716(15)
2.1411(18)
88.80(6)
92.21(6)
175.07(6)
93.71(6)
85.93(6)
91.82(6)
96.53(7)
O2–Zn1–O6
O2–Zn1–O8
O2–Zn1–N2
O6–Zn1–O8
O6–Zn1–N2
O7–Zn1–N1
O8–Zn1–N1
N1–Zn1–N2
of hydrogen bonds and face to face
p–p interactions consolidate
the complex 1.
In complex 2, coordinated water molecules in cationic motifs
form hydrogen bonds with 4-sb ligands through sulfonate and
carboxyl groups and these hydrogen-bonding interactions hold the
cationic motifs and anions into 3-D supra-molecular assembly
(Fig. 5). No any p–p stacking interaction can be found in complex 2.

90
J. Zhang, L.-G. Zhu / Journal of Molecular Structure 931 (2009) 87–93
Fig. 2. ORTEP view of the molecular structure of complex 2 (a) and 1-D cationic chain (b). Symmetry code: (i) 2-x, 2-y, 2-z; (ii) 1-x, 1-y, 1-z.
Fig. 3. ORTEP view of the molecular structure of complex 3 (a) and 1-D chain (b). Symmetry code: (i) 2-x, 2-y, 1-z; (ii) 1-x, 1-y, 1-z.

J. Zhang, L.-G. Zhu / Journal of Molecular Structure 931 (2009) 87–93
91
1317 cmꢁ1 for 1, 1545 and 1421 and 1377 cmꢁ1 for 2, and 1551
Table 3
and 1320 cmꢁ1 for 3, respectively. The characteristic vibrations of
Selected bond lengths (Å) and angles (°) for complex 2.
ꢁ
vs(SO3
)
are at 1220, 1196, 1117 cmꢁ1 in 1, 1228, 1176,
Zn1–O6
Zn1–O8
Zn1–N1
2.1875(15)
2.0977(14)
2.1393(15)
177.91(6)
88.08(6)
89.65(6)
93.99(6)
90.21(6)
88.91(6)
Zn1–O7
Zn1–O9
Zn1–N2
O6–Zn1–O8
O6–Zn1–N1
O7–Zn1–O8
O7–Zn1–N1
O8–Zn1–O9
O8–Zn1–N2
O9–Zn1–N2
2.1597(15)
2.1115(15)
2.1410(16)
91.05(6)
89.47(6)
86.89(6)
90.80(6)
178.91(5)
94.99(6)
1115 cmꢁ1 in 2, and 1229, 1183, 1162, 1119 cmꢁ1 in 3, respec-
tively; further vas(SO3ꢁ) peaks are at 1035 cmꢁ1 in 1, 1034 cmꢁ1
in 2, and 1036 cmꢁ1 in 3, respectively. The characteristic peaks of
the 2,20-bipyridine are at about 1598, 1443, and 767 cmꢁ1 in 1,
and 1609, 1446, 779 cmꢁ1 in 3.
O6–Zn1–O7
O6–Zn1–O9
O6–Zn1–N2
O7–Zn1–O9
O7–Zn1–N2
O8–Zn1–N1
O9–Zn1–N1
N1–Zn1–N2
3.5. Thermal stability behavior
90.43(6)
176.02(6)
85.66(6)
Thermal analyses of complexes 1–3 were done under a flow of
nitrogen gas from room temperature to 800 °C at heating rate of
10 °C minꢁ1. TG analysis for 1 shows that three-step weight loss
was observed from room temperature to 75 °C, 75–116 °C, and
117–130 °C. Total weight loss of 14.5% corresponds to the release
of four water molecules (calculated 14.6%). The complex decom-
posed at the range 250–780 °C with the loss of 2,20-bipy and 4-sb
ligands (calculated 68%, observed 67.8%), and the residue was
ZnO. For complex 2, the weight loss started at 66 °C, and in the
range 66–167 °C the total loss of 14.2% corresponds to the release
of four water molecules (calculated 14.6%). Complex 2 began to
decompose at 285 °C and ended at 658 °C with the loss of 4,40-bipy
and 4-sb ligands (calculated 68%, observed 67%), and the residue
was ZnO. Complex 3 released three water molecules from room
temperature to 100 °C with the weight loss of 9.5% (calculated
9.7%) and the complex decomposed at 243 °C. Complex 2 has the
higher temperature of water loss than those of complexes 1 and
3, which is agreement with the results that lattice water molecules
are easier to loss than that of coordinated water molecules.
Table 4
Selected bond lengths (Å) and angles (°) for complex 3.
Zn1–O1i
Zn1–O6
Zn1–N2
2.066(3)
2.141(4)
2.162(5)
Zn1–O3
Zn1–N1
Zn1–N3
2.164(4)
2.148(4)
2.164(4)
91.95(14)
93.15(15)
88.94(17)
169.27(14)
84.48(14)
173.24(16)
95.57(15)
O1i–Zn1–O3
O1i–Zn1–N1
O1i–Zn1–N3
O3–Zn1–N1
O3–Zn1–N3
O6–Zn1–N2
N1–Zn1–N2
N2–Zn1–N3
97.17(15)
168.95(17)
89.20(14)
93.22(16)
84.31(17)
93.64(17)
76.69(16)
92.94(17)
O1i–Zn1–O6
O1i–Zn1–N2
O3–Zn1–O6
O3–Zn1–N2
O6–Zn1–N1
O6–Zn1–N3
N1–Zn1–N3
Symmetry code: (i) 2-x, 2-y, 1-z.
In complex 3, hydrogen bonds between carboxyl groups and lat-
tice water molecules, between lattice water molecules, between
sulfonate groups and lattice water molecules, and between lattice
water molecules and coordinated water molecules extend the 1-D
zig-zag structure into a 3-D supra-molecular assembly (Fig. 6). Off-
3.6. Fluorescent emission
set face to face p–p
interactions occur between symmetrical 2,20-
Complexes 1–3 have the similar fluorescent properties in solid
state at room temperature (kex = 220 nm). The maximum emission
wavelengths occur at 470 nm in these three complexes. These
emissions may be mainly caused by 4-sb, 2,20-bipyridine, or/and
4,40-bipyridine ligands by comparison with the free ligands of
2.20-bipy, 4,40-bipy or K(4-Hsb). And these maximum emissions
in complexes 1–3 have the emission strength of 2 > 3 > 1, further-
more these emissions are stronger than free ligands, K(4-Hsb), 2,20-
bipyridine, and 4,40-bipyridine, indicating the coordination en-
hances the emission absorptions.
bipy rings with a centroid-to-centroid distance of 3.856(3) Å.
3.4. IR spectra analysis
In these three complexes, COOH characteristic peaks near
1680 cmꢁ1 are absent, indicating that each carboxyl group for 4-
sb ligands is deprotonated. The broad peaks at 3377 cmꢁ1 in 1,
3301 cmꢁ1 in 2, and 3427 cmꢁ1 in 3 suggest the presence of water
molecules in these three complexes. The symmetrical and unsym-
metrical peaks of carboxylates are observed at 1552 and
Fig. 4. A view of 3-D hydrogen-bonding architecture for complex 1.

92
J. Zhang, L.-G. Zhu / Journal of Molecular Structure 931 (2009) 87–93
Fig. 5. A view of 3-D hydrogen-bonding supra-molecular assembly for complex 2.
Fig. 6. A view of 3-D hydrogen-bonding supra-molecular assembly for complex 3.
analyses. These three complexes exhibit a monomer for complex
4. Conclusions
1, linear cationic chain in 2, and zig-zag chain for complex 3. In
the complexes containing 2,20-bipyridine ligands, 4-sb ligands
coordinate with metal ions, while in complex 2 the 4-sb is non-
coordinating. Hydrogen bonds are found in these three complexes,
Three ZnII/4-sulfobenzoate complexes based on 2,20-bipyridine
and/or 4,40-bipyridine ligands have been synthesized by hydro-
thermal synthesis and characterized by elemental analyses, IR
spectra, TG analyses, fluorescent spectra, and single-crystal X-ray
while
p–p interactions only occur in complexes 1 and 3. There is

J. Zhang, L.-G. Zhu / Journal of Molecular Structure 931 (2009) 87–93
93
p–p
interaction between 4,40-bipyridine ligands or 4,40-
[11] K.R. Gruenwald, A.M. Kirillov, M. Haukka, J. Sanchiz, A.J.L. Pombeiro, Dalton
Trans. (2009) 2109.
[12] J.Q. Chen, Y.P. Cai, H.C. Fang, Z.Y. Zhou, X.L. Zhan, G. Zhao, Z. Zhang, Cryst.
Growth Des. 9 (2008) 1605.
[13] L.P. Zhang, L.G. Zhu, J. Mol. Struct. 873 (2007) 61.
[14] J. Zhang, L.P. Zhang, L.G. Zhu, Chin. J. Inorg. Chem. 24 (2008) 27.
[15] L.P. Zhang, L.G. Zhu, Z. Anorg. Allg. Chem. 634 (2008) 39.
[16] L.P. Zhang, L.G. Zhu, CrystEngComm 8 (2006) 815.
[17] L.P. Zhang, L.G. Zhu, Acta Crystallogr. E61 (2005) m1768.
[18] S.R. Fan, H.P. Xiao, L.P. Zhang, L.G. Zhu, Acta Crystallogr. E60 (2004) m1833.
[19] S.R. Fan, H.P. Xiao, L.P. Zhang, G.Q. Cai, L.G. Zhu, Acta Crystallogr. E60 (2004)
m1970.
no any
bipyridine and 4-sb ligands. These extending hydrogen-bonding
supra-molecular assembles are 3-D architectures. These three di-
verse structures cause different properties, (1) complex 2 has the
highest water loss temperature; (2) the fluorescent emission
strength order is 2 > 3 > 1.
Acknowledgement
The authors thank the National Natural Science Foundation of
China (Grant No. 50073019).
[20] S. Bruker, AXS Inc., SAINT, version 6.02a, Madison, WI, 2002.
[21] G.M. Sheldrick, SADABS, Program for Bruker Area Detector Absorption
Correction, University of Göttingen, Germany, 1997.
[22] G.M. Sheldrick, SHELXL-97, Program for the Refinement of Crystal Structures,
University of Göttingen, Germany, 1997.
[23] L.J. Farrugia, WINGX: A Windows Program for Crystal Structure Analysis,
University of Glasgow, Great Britain, 1998.
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