Hydrothermal synthesis, crystal structure of five novel complexes based on 4-chlorophenyloxyacetic acid

Article abstract of DOI:10.1080/03610918.2013.767739

Five new metal-organic complexes of the formula [Pb₃L ₅(2,2′-bipy)₂(NO₃)(H₂O)] _n 1, [Cd₂L₄(1,10-Phenanthroline)₂] 2, [Mn₂L₄(1,10-Phena

Full text of DOI:10.1080/03610918.2013.767739

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Hydrothermal Synthesis, Crystal
Structure of Five Novel Complexes Based
on 4-Chlorophenyloxyacetic Acid
Long Li a , Kaisheng Diao a b , Yuqiu Ding a & Xianhong Yin a
a College of Chemistry and Chemical Engineering , Guangxi
University for Nationalities , Nanning , People's Republic of China
b Guangxi Key Laboratory of Chemistry and Engineering of Forest
Products , Guangxi University for Nationalities , Nanning , People's
Republic of China
Published online: 22 Apr 2013.
To cite this article: Long Li , Kaisheng Diao , Yuqiu Ding & Xianhong Yin (2013) Hydrothermal
Synthesis, Crystal Structure of Five Novel Complexes Based on 4-Chlorophenyloxyacetic Acid,
Molecular Crystals and Liquid Crystals, 575:1, 173-187, DOI: 10.1080/03610918.2013.767739
To link to this article: http://dx.doi.org/10.1080/03610918.2013.767739
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Mol. Cryst. Liq. Cryst., Vol. 575: pp. 173–187, 2013
Copyright © Taylor & Francis Group, LLC
ISSN: 1542-1406 print/1563-5287 online
DOI: 10.1080/03610918.2013.767739
Hydrothermal Synthesis, Crystal Structure
of Five Novel Complexes Based
on 4-Chlorophenyloxyacetic Acid
LONG LI,1 KAISHENG DIAO,1,2 YUQIU DING,1
AND XIANHONG YIN1,∗
1College of Chemistry and Chemical Engineering, Guangxi University for
Nationalities, Nanning, People’s Republic of China
2Guangxi Key Laboratory of Chemistry and Engineering of Forest Products,
Guangxi University for Nationalities, Nanning, People’s Republic of China
Five new metal–organic complexes of the formula [Pb3L5(2,2ꢀ-bipy)2(NO3)(H2O)]n
1, [Cd2L4(1,10-Phenanthroline)2] 2, [Mn2L4(1,10-Phenanthroline)2] 3, [Mn3L6(2,2ꢀ-
bipy)2] 4, and [PbL2(H2O)]n 5 [HL = 4-chlorophenyloxyacetic acid] have been syn-
thesized and characterized by IR method, elemental analysis, X-ray powder diffraction
(XRPD) analysis, fluorescence spectroscopy method, and single-crystal X-ray diffrac-
tion techniques. X-ray structure analysis reveals that complex 1 is 1D chain polymer,
complex 5 is 2D network polymer, while complex 2, 3, and 4 are all 0D structure. The L
ligand have many kinds of coordination mode, which make these complexes have differ-
ent configuration. The weak C–H···O and π–π interactions are also very important, the
mononuclear or multinuclear crystal units of these complexes can be packed through
them. Moreover, all these complexes exhibit fluorescence.
Keywords 4-chlorophenyloxyacetic acid; fluorescence; hydrothermal synthesis
Introduction
As far as we know, halogen phenoxyl carboxylates were widely used as excellent pesticide
and the plant auxin in agriculture in recent decades [1–4]. However, it can also pollutes
our environment and results in the intoxication of animals and humans [5]. In order to
decrease these intoxications, many researches focused on the degradation of the pesti-
cide. Coordinating halogen phenoxyl carboxylates with metal ion is a good way. Besides,
the self-assembly of metal ions and halogen phenoxyl carboxylates ligands have made
progress by detailed studies of their structural characteristics, such as diverse coordina-
tion modes and conformations, and their potential applications as catalysts, luminescent,
sorption, magnetic materials, and biological reagents [6–10]. As bridging ligands, halogen
phenoxyl carboxylates, are of huge interest in the construction of polymeric coordination
architectures not only because the fact that these polymers have a wide range of structural
diversities and potential applications as porous materials and magnetic materials, but also
∗Address correspondence to Xianhong Yin, College of Chemistry and Chemical Engineer-
ing, Guangxi University for Nationalities, Nanning 530006, People’s Republic of China. E-mail:
llgxmd@163.com
173

174
L. Li et al.
because these ligands exhibit rich coordination chemistry. 4-chlorophenyloxyacetic acid
is a typical halogen phenoxyl carboxylate ligand, to our knowledge, many of the most
interesting metal–organic polymers with one-, two-, and three-dimensional networks have
been engineered using anionic, carboxylate ligands, L has one flexible acetate.
However, no literatures related to the titled complexes have been published. Herein, we
report the synthesis, structure of five new complexes, [Pb3L5(2,2ꢀ-bipy)2(NO3)(H2O)]n 1,
[Cd2L4(1,10-Phenanthroline)2] 2, [Mn2L4(1,10-Phenanthroline)2] 3, [Mn3L6(2,2ꢀ-bipy)2]
4, and [PbL2(H2O)]n 5 [HL = 4-chlorophenyloxyacetic acid]. In addition, we investigate
the fluorescence of these complexes.
Experimental
Materials and Instrumentation
All reagents and solvents were used directly as supplied commercially without further
purification. Elemental analysis for C, H, and N was carried out on a Perkin–Elmer 2400
II elemental analyzer. The FT-IR spectrum was obtained on a PE spectrum one FT-IR
spectrometer Fourier transform infrared spectroscopy in the 4000–400 cm−1 regions, using
KBr pellets. The X-ray powder diffraction (XRPD) was recorded on a XD-3 diffractome-
ter (Beijing, China) at 36 kV, 25 mA for a Cu-target tube, and a graphite monochro-
mator. Simulation of the XRPD spectra was carried out by the single-crystal data and
Figure 1. The coordination environment of 1. Thermal ellipsoids are shown at 30% probability, all
H atoms are omitted for clarity.

Crystal Structure of Five Novel Complexes
175
Figure 2. A view of 1D infinite chain construct with C–O–Pb. Unnecessary atoms are omitted for
clarity.
Figure 3. The 2D layered network of complex 1 via π–π stacking interactions. Unnecessary atoms
are omitted for clarity.

176

Crystal Structure of Five Novel Complexes
177
Table 2. The selected bond lengths (Å) and angles (◦) for complex 1, 2, 3, 4, and 5
Complex 1
Pb (1)–O(11)
2.474(11)
2.492(12)
2.567(13)
2.591(13)
2.673(11)
2.884(11)
2.497(14)
2.499(13)
2.506(13)
2.666(12)
2.674(11)
2.702(12)
2.414(12)
2.463(11)
Pb(3)–O(18)
Pb(3)–O(17)
Pb(3)–O(11)
Pb(3)–O(14)
2.834(14)
2.752(13)
2.749(11)
2.654(13)
2.519(11)
101.5(3)
50.3(3)
120.0(4)
149.2(4)
71.6(4)
Pb(1)–O(9)
Pb(1)–N(4)
Pb(1)–N(3)
Pb(1)–O(8)
Pb(1)-O(6)
Pb(2)–N(1)
Pb(2)–O(5)
Pb(2)–N(2)
Pb(2)–O(2)
Pb(2)–O(15)a
Pb(2)–O(6)
Pb(3)–O(12)
Pb(3)-O(16)
Pb(3)–O(3)
O(11)–Pb(1)–O(8)
O(9)–Pb(1)–O(8)
N(4)–Pb(1)–O(8)
O(5)–Pb(2)–O(2)
O(5)–Pb(2)–O(15)a
N(2)–Pb(2)–O(6)
O(17)–Pb(3)–O(18)
O(16)–Pb(3)–O(14)
O(3)–Pb(3)–O(11)
82.6(4)
44.5(4)
78.0(4)
92.4(4)
Complex 2
Cd(1)–O(3)
Cd(1)–O(10)
Cd(1)–O(5)
Cd(1)–O(8)
Cd(1)–N(4)
Cd(1)–N(3)
Cd(2)–O(9)
Cd(2)–O(6)
Cd(2)–O(11)
2.237(3)
2.252(3)
2.319(4)
2.326(4)
2.385(4)
2.385(4)
2.242(4)
2.248(4)
2.296(4)
Cd(2)–O(2)
Cd(2)–N(2)
Cd(2)–N(1)
O(3)–Cd(1)–O(10)
O(10)–Cd(1)–O(8)
N(4)–Cd(1)–N(3)
O(9)–Cd(2)–O(6)
O(11)–Cd(2)–O(2)
O(11)–Cd(2)–N(2)
2.315(3)
2.400(4)
2.404(4)
161.66(11)
84.41(14)
69.13(16)
163.85(12)
128.60(12)
149.48(13)
Complex 3
Mn(1)–O(3)
Mn(1)–O(11)
Mn(1)–O(9)
Mn(1)–O(5)
Mn(1)–N(2)
Mn(1)–N(1)
Mn(2)–O(6)
Mn(2)–O(8)
2.124(3)
2.151(4)
2.210(5)
2.216(4)
2.309(4)
2.316(5)
2.119(4)
2.137(4)
Mn(2)–O(12)
Mn(2)–O(2)
Mn(2)–N(3)
Mn(2)–N(4)
O(3)–Mn(1)–O(11)
N(2)–Mn(1)–N(1)
O(12)–Mn(2)–O(2)
N(3)–Mn(2)–N(4)
2.195(3)
2.217(4)
2.341(4)
2.345(5)
161.43(15)
70.71(17)
126.29(15)
70.14(14)
Complex 4
Mn(1)–O(8)
Mn(1)–O(2)
Mn(1)–O(5)
Mn(1)–N(2)
Mn(1)–N(1)
Mn(2)–O(6)
Mn(2)–O(6)a
Mn(2)–O(3)
2.069(4)
2.103(4)
2.122(4)
2.254(4)
2.266(4)
2.137(4)
2.137(4)
2.161(3)
Mn(2)–O(3)a
2.161(3)
2.196(4)
2.196(4)
97.42(16)
106.59(16)
90.88(16)
93.11(14)
88.06(15)
Mn(2)–O(9)a
Mn(2)–O(9)
O(2)–Mn(1)–O(5)
O(8)–Mn(1)–O(2)
O(6)–Mn(2)–O(3)
O(3)–Mn(2)–O(9)
O(6)–Mn(2)–O(9)
Complex 5
Pb(1)–O(5)
Pb(1)–O(3)
Pb(1)–O(7)
Pb(1)–O(5)a
Pb(1)–O(6)
2.505(15)
2.51(2)
2.61(2)
2.644(14)
2.664(16)
Pb(1)–O(6)b
2.696(17)
2.711(16)
50.7(5)
118.3(5)
147.6(5)
Pb(1)–O(2)c
O(5)–Pb(1)–O(6)
O(5)–Pb(1)–O(6)b
O(6)–Pb(1)–O(2)c
Symmetry transformations used to generate equivalent atoms:
afor Complex 1: x + 1, y, z; afor Complex 4: –x + 1, –y + 1,–z + 2;
afor Complex 5: –x, –y + 1, –z; bfor Complex 5: –x, –y + 2, –z;
cfor Complex 5: x – 1, y, z.

178
L. Li et al.
Table 3. Hydrogen-bond geometry (Å) of complexes
D H···A
Complex 1
O16–H16D···O5
O16–H16C···O12
Complex 5
D H
H···A
D···A
D H···A
Symmetry codes
x – 1, y, z
0.850
0.850
2.02
1.98
2.859(16)
2.825(17)
169.6
169.4
O7–H7F···O5
0.850
0.850
2.37
2.04
3.20(3)
2.87(3)
167.0
166.6
O7–H7E···O3
x – 1, y, z
diffraction-crystal module of the Mercury (Hg) program available free of charge via
the Internet at http://www.iucr.org. Excitation and emission spectra were acquired on a
Perkin–Elmer instruments LS55 spectrofluorometer.
Synthesis of the Complex [Pb3L5(2,2ꢀ-bipy)2(NO3)(H2O)]n 1
A mixture of Pb(NO3)2 (165.5 mg, 0.3 mmol), HL (111.8 mg, 0.6 mmol), and 2,2ꢀ-bipy
(46.2 mg, 0.3 mmol) were dissolved in the mixed solvent (1:1 H2O/EtOH) (20 mL). Then,
an aqueous solution of sodium hydroxide was added dropwise with stirring to adjust the
pH value of the solution being 6. The mixture was kept heated at 130◦C for 3 days. After
Figure 4. The coordination environment of 2. Thermal ellipsoids are shown at 30% probability, all
H atoms are omitted for clarity.

Crystal Structure of Five Novel Complexes
179
Figure 5. A view of 2D supramolecular structure and π–π stacking interactions of complex 2.
Unnecessary atoms are omitted for clarity.
Figure 6. The coordination environment of 3. Thermal ellipsoids are shown at 30% probability, all
H atoms are omitted for clarity.

180
L. Li et al.
Figure 7. The coordination environment of 4. Thermal ellipsoids are shown at 30% probability, all
H atoms are omitted for clarity.
cooling to room temperature, the reaction solution was filtered to remove a small quantity
of precipitation. Kept slow evaporation of the filtrate at room temperature and four days
later X-ray quality colorless block-shaped single crystals were obtained. The crystals were
isolated, washed with ethanol, and dried at room temperature (Yield: 55% based on Pb).
Calcd. For C60H48Cl5N5O19Pb3: C 37.09, H 2.47, N 3.60%. Found: C 36.15,H 2.43, N
3.64%. IR (KBr, cm−1): 3060 (w), 1618 (w), 1596 (s), 1491 (s), 1380 (s), 1242 (m), 821
(w), 724 (s).
Synthesis of the Complex [Cd2L4(1,10-Phenanthroline)2] 2
The synthesis of 2 was similar to that of 1 except that CdCl2·2.5H2O (68.4 mg,
0.3 mmol) was used instead of Pb(NO3)2 (165.5 mg, 0.3 mmol), and 2,2ꢀ-bipy (46.2 mg,
0.3 mmol) was replaced by 1,10-Phenanthroline (54 mg, 0.3 mmol). A week later, colorless
block-shaped single crystals were obtained. The crystals were isolated, washed with ethanol,
and dried at room temperature (Yield:70% based on Cd). Calcd.For C56H40Cl4Cd2N4O12:
C 50.64, H 3.01, N 4.22%. Found: C 50.59,H 3.07, N 4.18%. IR (KBr, cm−1): 3074 (w),
1662 (w), 1593 (s), 1492 (s), 1426 (s), 1244 (m), 822 (w), 726 (s).
Synthesis of the Complex [Mn2L4(1,10-Phenanthroline)2] 3
The synthesis of 3 was similar to that of 2 except that MnCl2·4H2O (58.2 mg, 0.3 mmol)
was used instead of CdCl2·2.5H2O (68.4 mg, 0.3 mmol). Four days later, yellow block-
shaped single crystals were obtained. The crystals were isolated, washed with ethanol, and
dried at room temperature (Yield:65% based on Mn). Calcd.For C56H40Cl4Mn2N4O12: C
55.44, H 3.30, N 5.28%. Found: C 55.38,H 3.36, N 5.22%. 3082 (w), 1667 (s), 1593 (w),
1492 (s), 1429 (s), 1246 (m), 822 (w), 726 (s).

Crystal Structure of Five Novel Complexes
181
Figure 8. A perspective view of the 2D layered network via C–H···O and π–π stacking interactions.
Figure 9. The weak C–H···π interaction in complex 4.

182
L. Li et al.
Synthesis of the Complex [Mn3L6(2,2ꢀ-bipy)2] 4
A mixture of MnCl2·4H2O (58.2 mg, 0.3 mmol), HL (111.8 mg, 0.6 mmol), and 2,2ꢀ-
bipy (46.2 mg, 0.3 mmol) were dissolved in the mixed solvent (1:1 H2O/EtOH) (20 mL).
Then, an aqueous solution of sodium hydroxide was added dropwise with stirring to adjust
the pH value of the solution being 6. The mixture was kept heated at 130◦C for 3 days. After
cooling to room temperature, the reaction solution was filtered to remove a small quantity
of precipitation. Kept slow evaporation of the filtrate at room temperature and four days
later X-ray quality yellow block-shaped single crystals were obtained. The crystals were
isolated, washed with ethanol, and dried at room temperature (Yield: 62% based on Mn).
Calcd. For C68H52Cl6N4O18Mn3: C 51.32, H 3.27, N 4.02%. Found: C 51.28, H 3.24, N
3.99%. IR (KBr, cm−1): 3116 (w), 1614 (s), 1598 (w), 1491 (s), 1411 (s), 1223 (m), 827
(m), 719 (w).
Synthesis of the Complex [PbL2(H2O)]n 5
A mixture of Pb(NO3)2 (165.5 mg, 0.3 mmol) and HL (111.8 mg, 0.6 mmol) were
dissolved in the mixed solvent (1:1 H2O/EtOH) (20 mL). Using an aqueous solution of
sodium hydroxide to adjust the pH value being 6. The mixture was kept heated at 130◦C
for 3 days. After cooling to room temperature, we get the colorless block-shaped single
crystals. The X-ray quality crystals were isolated, washed with ethanol and dried at room
temperature (Yield: 65% based on Pb). Calcd. For C16H14Cl2O7Pb: C 32.21, H 2.34%.
Found: C 32.19, H 2.38%. IR (KBr, cm−1): 3093 (w), 1619 (w), 1592 (w), 1492 (s), 1434
(m), 1239 (s), 821 (w), 720 (m).
X-Ray Data Collection and Structure Refinement
Crystallographic data of complexe was collected on a Bruker SMART CCD diffractometer
with graphite monochromated Mo–Ka radiation (λ = 0.71073 Å) at T = 296 K.Absorption
corrections were applied by using the multi-scan program [11]. The structure was solved by
direct methods and successive Fourier difference syntheses (SHELXS-97), and anisotropic
thermal parameters for all nonhydrogen atomswere refined by full-matrix least-squares
procedure against F2 (SHELXL-97) [12]. All nonhydrogen atoms were refined anisotropi-
cally. Hydrogen atoms were set in calculated positions and refined by a riding mode, with a
common thermal parameter. H atoms for H2O molecules were located in different synthesis
and refined isotropically. Complex 2 and 3 are both have one disorder L ligand, in complex
3, I did not set all hydrogens of the disorder L ligand, I just create some hydrogens and
alter their occupancy to get the correct formula. The crystallographic data and experimental
details for the structure analysis are summarized in Table 1, the selected bond lengths and
angles are listed in Table 2, meanwhile, the hydrogen-bonds of the complexes are listed in
Table 3.
Results and Discussion
Crystal Structure Descriptions
Single crystal X-ray analysis of 1 reveals that the asymmetric unit consists of three Pb(II)
ions, two 2,2ꢀ-bipy, four L ligands, one NO3 anion, and one water. The Pb(II) ion in
−
complex 1 has two kinds of coordination number, The Pb1 coordinate with two nitrogen
atoms (N3, N4) from one 2,2ꢀ-bipy, with two oxygen atoms (O8, O9) from the carboxylate
of L ligand and with two oxygen atoms (O6, O11) from the carboxylate of different two L
ligands. Each Pb2 is coordinated by two nitrogen atoms (N1, N2) from one 2,2ꢀ-bipy, by

Crystal Structure of Five Novel Complexes
183
two oxygen atoms (O8, O9) from the carboxylate of L ligand and by two oxygen atoms
(O2, O15) from the carboxylate of two different L ligands. The Pb3 coordinate with two
oxygen atoms (O11, O12) from the a L ligand, with two oxygen atoms (O3, O14) from two
different L ligands, with one oxygen atom (O16) from a coordinated water, and two oxygen
atoms (O17, O18) from a NO3− anion. The different coordination number make each Pb1
and Pb2 adopt a distorted octahedral coordination, make Pb3 form a distorted decanedron
coordination. We can see the environment of Pb in Fig. 1. The L ligand in complex 1 has
three kinds of coordination modes: one is chelating, one displays a bridging bidentate, and
the third adopts a bridging tridentate, which linked Pb ions together and extended in a axis
direction to be a 1D chain (Fig. 2). The protrudent 2,2ꢀ-bipy molecules play an important
role in structure construction as interlinkages by π–π stacking interactions with the phenyl
rings from 2,2ꢀ-bipy molecules of adjacent chains into 2D supramolecular layer in ab plane.
The centroid-to-centroid distances of π–π stacking interactions among the phenyl rings
of 2,2ꢀ-bipy molecules and two phenyl rings of two neighboring 2,2ꢀ-bipy molecules are
3.779 and 3.848 Å (Fig. 3). In addition, the π–π stacking interactions also exist between
two benzene rings of L ligands from adjacent layers (3.896 Å, 5.97◦), which connected
these 2D layers to be a 3D supermolecular structure. The hydrogen bonds in complex 1
also make the structure to be more stable.
As shown in Fig. 4 for compound 2, all L ligands exhibit chelating bidentate arrange-
ment. Compound 2 show us a 0D structure, there are two independent Cd(II) centers exist in
the unit. Each Cd(II) adopts a slightly distorted octahedral coordination, are six coordinated
by four oxygen atoms from the carboxylate of four different L ligands and two nitrogen
atoms from one 2,2ꢀ-bipy. The nonbonding Cd1·Cd2 distance is 3.571 Å, four L ligands
linked the two Cd(II) centers together through the chelating bidentate carboxylate. The two
1,10-phenanthroline coordinated with two Cd(II) at the opposite position, and the dihedral
angle between them is 69.06◦. There are π–π stacking interactions between the adjacent
1,10-phenanthroline of which the intercentroid distance being depicted in Fig. 5. These
π–π stacking interactions construct complex 2 to be a two-dimensional supramolecular
structure.
The X-ray structure shows that complex 3 has the same structure with compound 2.
The asymmetric unit of complex 3 consists of two Mn(II) ions, four L ligands and two
1,10-phenanthroline molecules. Each Mn(II) coordinate with four oxygen atoms from the
carboxylate of four L ligands and two nitrogen atoms from a 2,2ꢀ-bipy (Fig. 6). The π–π
stacking interactions also exist between the adjacent 1,10-phenanthroline, which paly an
important part in the structure construction.
A perspective view of the molecular structure of the complex 4 along with the atom-
numbering scheme is depicted in Fig. 7. The Mn(II) ion in complex 4 has two kinds of
coordination number, each Mn1 coordinate with two nitrogen atoms (N1, N2) from one
2,2ꢀ-biphenyl and three oxygen atoms (O2, O5, O8) from three different bridging L ligands
adopts a distorted hexahedron coordination, the Mn2 coordinate with six oxygen atoms
from the carboxylate of six bridging bidentate L ligands show a slightly distorted octahe-
dral coordination. The six L ligands linked three Mn ions together and make the structure
become a dimer. The 0D dimer are linked by weak C31–H31···O5, C28–H28···O5, and
C22–H22···O4 interactions and by π–π stacking to yield a layered network (Fig. 8). The
2D layers in complex 4 are packed alongside with eachother through weak C–H···π inter-
actions (Fig. 9). Along with this shortest interaction (H19 to the centroid of ring C9–C14:
3.297 Å) propagating crystallographic c axis with the formation of a 3D supermolecule
structure.

184
L. Li et al.
Figure 10. The coordination environment of 5. Thermal ellipsoids are shown at 30% probability, all
H atoms are omitted for clarity.
The X-ray structure shows that complex 5 adopts a 2D network polymer. The Pb(II)
central atoms, which have decanedron coordination, are seven-coordinated by six oxygen
atoms from five L ligands and one oxygen atom from a coordinated water (Fig. 10). The
carboxylate group of L ligand exhibit bridging bidentate and chelating-bridging quadriden-
tate modes. As shown in Fig. 11, complex 5 is stabilized through the C-O-Pb frame and
weak O7–H7E···O3, O7–H7F···O5 hydrogen bonds.
Figure 11. A perspective view of C–O–Pb frame and weak hydrogen bonds.

Crystal Structure of Five Novel Complexes
185
Figure 12. Simulated and experimental XRPD patterns for complex 1, 2, 3, and 4.
The structural consistency and phase purity of 1, 2, 3, and 4 were confirmed by
comparing the measured pattern calculated from single-crystal data with the experimental
X-ray powder diffraction (XRPD) analysis at room temperature (Fig. 12).
IR Spectroscopy
The IR spectrum of c−om1 plex 1, 2, 3, 4, and 5 are exhibit two peaks at 1618 cm−1 and
1380 cm−1, 1662 cm and 1426 cm−1, 1667 cm−1 and 1429 cm−1, 1614 cm−1 and
1411 cm−1, 1619 cm−1 and 1434 cm−1, respectively. which are assigned to the νCOO–
stretching vibration and indicate the coordination of the carboxylate group of L ligand
to metal for the large red-shift compared with the IR spectrum of the free L ligand. The
skeleton vibration bands of the phenyl ring appearing at 3060, 1596, and 1491 in 1; 3074,
1593, and 1492 in 2; 3082, 1593, and 1492 in 3; 3116, 1598, and 1491 in 4; and 3093,
1592, and 1492 in 5. Furthermore, the band at around 822 cm−1 in all these complexes
are attributable to the γ ( C–H) of 1, 4-substituted phenyl ring, and the peak at around
724 cm−1 can be attributed to the γ (–CH 2–) of the ligand.
Fluorescence Emission Properties
The photoluminescence behavior of the free ligand (HL) and its corresponding manganese
(II), cadmium (II), plumbum (II) compounds were studied in the solution of methanol at
room temperature. The excitation and emission spectra of HL, 1, 2, 3, 4, and 5 are depicted
in Fig. 13. Upon photoexcitation at 288 nm, the free HL exhibits fluorescence emission at
310 nm. Upon excitation at 336 nm, the compound 1 show more intense photoluminescence
with the main emission at 375 nm. Compound 2 exhibits emission around 370 nm upon
excitation at 326 nm. Upon photoexcitation at 360 nm, compound 3 show a broad emission

186
L. Li et al.
Figure 13. Photoluminescent spectrum of HL ligand and complex 1, 2, 3, 4, and 5 in the solution of
methanol at room temperature.
peak at 410 nm. Compound 4 exhibits emission around 424 nm upon excitation at 343 nm.
Upon photoexcitation at 322 nm, compound 5 exhibits fluorescence emission at 388 nm.
The emission band for compound 1, 2, 3, 4, and 5 are different to that found for the free
ligand in terms of position and band shape. Therefore, the luminescence behaviors in these
complexes may be attributed to the intraligand (π–π∗) transition, and greater intensity
may presumably be due to the increase in conformational rigidity of the ligand upon
coordination. Meanwhile, compared with the emission spectrum of HL, a largely red shift
in these five complexes have been observed, which is considered to mainly arise from the
coordination effect of metal (II) with the ligand. Furthermore, the incorporation of metal
(II) effectively increases the conformational rigidity of HL and reduces the loss of energy
via vibration motions. Thus, the enhanced fluorescence intensities of the five compounds
are detected.
Conclusion
This paper reports the synthesis and characterization of complexes [Pb3L5(2,2ꢀ-
bipy)2(NO3)(H2O)]n, [Cd2L4(1,10-Phenanthroline)2], [Mn2L4(1,10-Phenanthroline)2],
[Mn3L6(2,2ꢀ-bipy)2], and [PbL2(H2O)]n by IR method, elemental analysis, XRPD anal-
ysis, fluorescence spectroscopy method, and single-crystal X-ray diffraction techniques.
The above results show that the configuration of ligand plays an important role in af-
fecting the final structure of the coordination polymers. The successful preparation of the
complexes manifest that the conformations and functions of π–π stacking interactions,

Crystal Structure of Five Novel Complexes
187
hydrogen bonds and van der Waals’ forces are important factors in influencing the architec-
ture of metal-L ligand complexes. In addition, Compound 1, 2, 3, 4, and 5 are all exhibits
fluorescence in the solution of methanol at room temperature.
Supplementary Material
CCDC 904945, 904949, 904946, 904947, and 904948 contains the supplementary
crystallographic data for this paper. These data can be obtained free of charge via
www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data
Centre, 12, Union Road, Cambridge CB2 1EZ, UK; fax: C44 1223 336033; e-mail: de-
posit@ccdc.cam.ac.uk).
Acknowledgments
This work is supported by the Innovation Project of Guangxi University for Nationalities
(gxun-chx2012089), the Scientific Research Program of Education Department of Guangxi
Zhuang Autonomous Region (Project No. 201010LX081), and the Scientific Research
Program of Guangxi University for Nationalities (Project No. 2010QD019).
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