Synthesis, structures of four coordination compounds constructed from o-methacrylamidobenzoic acid and their relationship between structure and solid state luminescence

Article abstract of DOI:10.1016/j.jssc.2013.03.055

Four new coordination compounds, namely, Zn(o-MAABA)₂(Phen) (1), [Cd(o-MAABA)₂ · 2H₂O]₂ (2), {[Pb ₂Cl₂(o-MAABA)₂(Phen)₄]} · 2H₂O (3 · 2H₂O), [Pb(

Full text of DOI:10.1016/j.jssc.2013.03.055

Journal of Solid State Chemistry 203 (2013) 1–7
Contents lists available at SciVerse ScienceDirect
Journal of Solid State Chemistry
journal homepage: www.elsevier.com/locate/jssc
Synthesis, structures of four coordination compounds constructed
from o-methacrylamidobenzoic acid and their relationship between
structure and solid state luminescence
n
Hong-Xia Chen a,b, Yong Ma a,b, Feng Zhou a,b, Bing Wu a,b, Qing-Feng Xu a,b,
,
n
Jian-Mei Lu a,b, , Jian-Feng Ge a,b
a Key Laboratory of Organic Synthesis of Jiangsu Province, School of Chemistry, Chemical Engineering and Materials Science, Soochow University(DuShuHu
Campus), 199 Renai Road, Suzhou, 215123, China
b Key Laboratory of Energy-Saving And Environmental Protection Materials Test & Technical Service Center of Jiangsu Province, Soochow University
(DuShuHu Campus), 199 Renai Road, Suzhou, 215123, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Four new coordination compounds, namely, Zn(o-MAABA)2(Phen) (1), [Cd(o-MAABA)2 ꢀ 2H2O]2 (2),
{[Pb2Cl2(o-MAABA)2(Phen)4]} ꢀ 2H2O (3 ꢀ 2H2O), [Pb(NO3)(o-MAABA)(Phen)]n (4), where o-MAABA¼
o-methacrylamidobenzoic acid and phen¼1, 10-phenanthroline, have been synthesized. All compounds
were fully confirmed by FT-IR, elemental analysis and TGA analysis. Their structures were determined by
single crystal X-ray diffraction, in which compound 1 shows a mononuclear structure, compounds 2 and
3 have binuclear structures and compound 4 shows an infinite chain. In 2 and 4, the adjacent chains are
extended into a 3D supramolecular architecture via π–π interactions. Solid-state room temperature
Received 17 January 2013
Received in revised form
22 March 2013
Accepted 26 March 2013
Available online 4 April 2013
Keywords:
o-Mmethacrylamidobenzoic acid
Crystal structure
1,10-Phenanthroline
Luminescent properties
luminescence spectra revealed that emission bands of compound
1 were located at 524 nm
(λex ¼352 nm) and compound 4 at 479 and 584 nm (λex¼390 nm) assigned to the excimer formation.
The emission at 454 nm (λex ¼340 nm) of compound 2 was mainly ascribed to the Ligand–Metal Charge
Transfer (LMCT).
Crown Copyright & 2013 Published by Elsevier Inc. All rights reserved.
1. Introduction
5-Benzenetetracarboxylate [6], pyridine [7], pyrazole [8], and imi-
dazoledicarboxylate [9]), neutral organonitrogen bridging
During the past decades, considerable efforts have been
devoted to construct new coordination compounds, not only
owing to their enormous variety of intriguing structural topologies
but also because of their great potential applications as micro-
porous, magnetic, and non-linear optical and fluorescent materials
[1,2]. The selection of multifunctional organic ligands containing
appropriate coordination sites linked by a spacer with specific
positional orientation is especially crucial to the construction of
desirable frameworks [3]. Thus, much attention has been paid to
the various multifunctional bridging ligands and the structure
diversities accordingly. So far, organic ligands, mainly including
the aromatic/heterocyclic multicarboxylate compounds (e.g. 1,4-
benzenedicarboxylate [4], 1,3,5-benzenetricarboxylate [5], 1,2,4,
ligands such as 4, 4′-bipy and derivatives and terminal aromatic
chelating ligands such as 2, 2′-bpy [10], 1, 10-phen [11], have been
widely used for the design and synthesis of functional crystalline
solids.
Recently, bridging ligands, for example, multidentate aromatic
ligands containing multiple coordination sites such as the N-
heterocyclic group and carboxylate group have been extensively
studied and proved to be a rational choice to synthesize coordina-
tion compounds with unique structures and potential applications
[12,13]. In this paper, o-methacrylamidobenzoic acid (o-MAABA), a
multi-functional ligand, containing amide and carboxylate groups:
carboxylate group can be used as an efficient “spacer” in designing
novel coordination polymers since it contains versatile coordina-
tion modes as well as its hydrogen bonding capability [14–16].
Moreover, the electron delocalization of amide backbone results in
becoming a chelate ring and then coordinates with the metals
more stable [15(c),15(d)]. Herein, the use of o-methacrylamidoben-
zoic acid and 1,10-phenanthroline for constructing coordination
compounds namely, Zn(o-MAABA)2(Phen) (1), [Cd(o-MAABA)2 ꢀ
2H2O]2 (2), {[Pb2Cl2(o-MAABA)2(Phen)4]} ꢀ 2H2O (3 ꢀ 2H2O), [Pb
n
Corresponding authors at. Key Laboratory of Organic Synthesis of Jiangsu
Province, School of Chemistry, Chemical Engineering and Materials Science,
Soochow University(DuShuHu Campus), 199 Renai Road, Suzhou, 215123, China.
Tel.: +86 512 65880367; fax: +86 512 6588 2875.
E-mail addresses: xuqingfeng@suda.edu.cn (Q.-F. Xu),
lujm@suda.edu.cn (J.-M. Lu).
0022-4596/$ - see front matter Crown Copyright & 2013 Published by Elsevier Inc. All rights reserved.
http://dx.doi.org/10.1016/j.jssc.2013.03.055

2
H.-X. Chen et al. / Journal of Solid State Chemistry 203 (2013) 1–7
(NO3)(o-MAABA)(Phen)]n (4) were reported. All the compounds
were characterized by X-ray crystallography, elemental analysis,
infrared spectra (IR), powder X-ray diffraction (PXRD) and thermo-
gravimetric analyses (TGA). The structures and topological analyses
of these compounds reveal that compound 1 shows a mononuclear
structure, compounds 2 and 3 have binuclear structures and
compound 4 shows an infinite chain. Furthermore, the photolumi-
nescent properties of all compounds and o-MAABA in DMF solu-
tion and solid state have also been investigated. Although the
emission bands in DMF solution were all similar, there are
differences in PL properties between the ligand o-MAABA and
compounds 1, 2, 4 which may be attributed to the molecular
stacking and LMCT, respectively.
sealed tube) at 223 K (for compounds 1, 3 and 4) and an Xcalibur Atlas
Gemini CCD X-ray diffractometer (50 KV, Enhance (Mo) X-ray Source)
at 293 K (for compound 2) using graphite monochromated Mo Kα and
a suitable single crystal mounted at the top of a glass fiber. Diffraction
data were collected in ω mode and reduced using the program
CrystalClear (Rigaku and MSC, Ver. 1.3, 2001) and the application of
a semi-empirical absorption correction. The reflection data were
further corrected for Lorentz and polarization effects. The structure
was solved using SHELXS-97 software and refined using Full-matrix
least-squares on F2 in the SHELXL-97 program [17]. The Cl2 atom in
compound 3 was added at the 2-fold axis. All calculations were
performed on a Dell workstation using the Shelxs software package.
Most of the hydrogen atoms in compound 3 were introduced at the
calculated positions and included in the structure-factor calculations. A
summary of the key crystallographic information for compounds 1–4
are given in Table 1. The selected bond lengths and bond angles of
compounds 1–4 are listed in Table 2.
2. Experimental section
2.1. Materials and measurements
All the reagents for synthesis were obtained commercially,
purified by standard methods prior to use, and characterized using
1H NMR, elemental analysis and IR spectra. Elemental analysis of C,
H and N was performed by the Elemental Analysis Service using an
EA1110-CHNS elemental analyzer. Infrared spectra were measured
as KBr disks on a MagNa-550 FT-IR system. The solid-state
luminescent spectra were measured on a Perkin-Elmer LS55
spectrofluorometer at room temperature. Thermal gravimetric
analysis (TGA) was conducted on a Universal V3.7 A TA instrument
in flowing N2 with a heating rate of 10 1C/min. 1H NMR spectra
were recorded on a Bruker AC-P500 spectrometer (400 MHz) in
DMSO-d6 medium at 25 1C with tetramethylsilane as the internal
reference. Powder X-ray diffraction (PXRD) was recorded on a
Rigaku D/Max-2500 diffractometer at 40 kV and 100 Ma with a
Cu-target tube and a graphite monochromator.
2.3. Synthesis
2.3.1. Synthesis and characterization of o-methacrylamidobenzoic
acid (o-MAABA)
2-methacrylamidobenzoic acid (o-MAABA): the 2-aminobenzoic
acid (0.05 mol, 6.85 g) in 50 ml THF solution was cooled in an ice bath
and stirred mechanically. To the solution, 10.10 g triethylamine
(0.1 mol) was added, after stirring for 0.5 h, 6.27 g methacryloyl
chloride (0.06 mol) was added into the mixture, then the mixture
was stirred in ice bath for 1 h then the mixture was stirred at room
temperature for another 5 h. The precipitate was removed from the
reaction mixture by suction filtration. The filtrate was poured into
water then a little of precipitate was removed from the filtrate by
suction filtration again. The resulting filtrate was washed with Et2O
(3 ꢁ 10 ml), then 1% hydrochloric acid was poured into the washed
filtrate while stirring. The resulting precipitate was collected by suction
filtration and dried under vacuum. Yield: 53% (5.44 g). Anal. calc. for
C11H11NO3(%): C, 64.32, H, 58.96, N, 6.82, Found: C, 64.40, H, 59.05, N,
6.78. 1H NMR(DMSO-d6, 400 MHz): (δ, ppm): 13.5–13.9(1H, OH),
11.5–11.8(1H, NH), 6.5–8.5(4H, ArH), 5.8–6.0(2H, CH2), 1.8–2.0(3H, CH3).
2.2. X-ray diffraction crystallography
All measurements were made on two different CCD X-ray diffract-
ometers which are a Rigaku Mercury CCD X-ray diffractometer (50 KV,
Table 1
Crystallographic data for compounds 1–4.
Compounds
1
2
3
4
Formula
Fw
T(K)
Crystal system
Space group
a (Å)
b (Å)
c (Å)
α(deg)
β(deg)
C34H28N4O6Zn
653.97
223(2)
Monoclinic
C 2/c
20.608(4)
15.235(3)
9.4214(16)
90
102.590(5)
90
2886.8(9)
4
C22H24CdN2O8
556.83
293(2)
Triclinic
P-1
8.9842(5)
10.1349(8)
13.8013(10)
80.705(6)
87.854(5)
72.433(6)
1182.25(14)
2
C70H56Cl2N10O8Pb2
1650.53
223(2)
Monoclinic
C 2/c
32.394(4)
10.3254(12)
21.126(3)
90
118.263(3)
90
C23H15N4O6Pb
650.58
223(2)
Triclinic
P-1
7.9963(11)
9.9322(14)
14.448(2)
76.013(9)
85.738(12)
79.627(12)
1094.7(3)
2
γ(deg)
3
V(Å
Z
)
6223.9(14)
4
Dcalc
1.505
0.906
1352
1.564
0.972
564
1.761
5.556
3232
1.974
7.755
622
μ(mm-1
F(000)
)
Crystal size(mm)
Θmax(1)
0.35 ꢁ 0.10 ꢁ 0.10
0.10 ꢁ 0.20 ꢁ 0.20
0.60 ꢁ 0.40 ꢁ 0.30
0.20 ꢁ 0.10 ꢁ 0.08
27.47
26.37
27.49
27.50
Reflections collected
Independent reflections
Observed reflections
Parameters refined
R(I42s(I))
8207
3253
2065
206
0.0690
0.1322
1.119
14531
4829
3992
306
0.0334
0.1058
0.746
17303
7090
5755
425
0.0505
0.1274
1.068
10032
4916
4211
309
0.0491
0.0814
1.078
wR2(all data)
GOF on F2

H.-X. Chen et al. / Journal of Solid State Chemistry 203 (2013) 1–7
3
2.3.2. Synthesis of Zn(o-MAABA)2(phen) (1)
2.3.3. Synthesis of [cd(o-MAABA)2 ꢀ 2H2O]2 (2)
To the solution of o-MAABA (20.5 mg, 0.1 mmol) in water
(5 mL), the pH value was adjusted to ca. 7–8 by adding 0.1 M
NaOH methanol solution. The ZnCl2 (6.8 mg/2.5 ml, 0.05 mmol)
and 1,10-Phen ꢀ H2O (10 mg/2.5 ml, 0.05 mol) methanol solution
were added slowly to the above solution (Scheme 1). The mixture
was stirred and refluxed for another 2 h. Colorless prisms of 1
were obtained after one day at room temperature, which were
isolated by filtration, washed with Et2O, and dried in vacuo. The
final yield of 1 was 13.5 mg (41%). Anal. Calcd for C34H28N4O6Zn
(1): C, 65.39; H, 4.28; N, 8.56. Found: C,65.34; H, 4.26; N, 8.50. IR
(KBr,cm−1): 3479 (b), 3063(w), 1916(w), 1670(s), 1620(m), 1587(s),
1512(s), 1425(s), 1381(m), 1310(s), 1225(m), 1178(w), 1149(m), 1109
(m), 1040(w), 1011(w), 950(m), 863(s), 769(m), 725(s), 678(w), 640
(m).
Compound 2 was synthesized following a similar procedure in
1, except CdCl2 ꢀ 2.5H2O (11.4 mg, 0.05 mmol) as used (Scheme 1).
Colorless crystals of compound 2 were obtained from solvent
evaporation for two days and isolated by filtration (Scheme 1).
Yield: 8.4 mg (30%). Anal. Calc. For C22H24CdN2O8: C, 47.41; H,
4.31; N, 5.03. Found: C, 47.47; H, 4.30; N, 4.96. IR (KBr, cm−1): 3468
(b), 3099(w), 1750(w), 1677(s), 1617(m), 1589(s), 1507(s), 1449(m),
1424(m), 1364(m), 1307(m), 1287(s), 1231(w), 1165(w), 1039(w),
955(w), 933(w), 845(m), 761(s), 720(m), 680(w), 648(w).
2.3.4. Synthesis of {[ Pb2Cl2(o-MAABA)2(phen)4]} ꢀ 2H2O (3 ꢀ 2H2O)
Compound 3 was synthesized following a similar procedure in
1, except PbCl2 (13.9 mg, 0.05 mmol) as used (Scheme 1). Color-
less crystals of compound 3 were obtained from solvent evapora-
tion for few days and isolated by filtration (Scheme 1). Yield:
28.9 mg (35%). Anal. Calc. For C70H56Cl2N10O8Pb: C, 50.89; H, 3.39;
N, 8.48. Found: C, 50.93; H, 3.48; N, 8.40. IR (KBr, cm−1): 3388 (b),
3059(w), 1831(w), 2873(s), 1646(w), 1617(w), 1587(m), 1561(m),
1504(m), 1422(s), 1344(w), 1217(w), 1139(w), 1091(m), 987(w),
843(s), 778(w), 707(m), 623(m).
Table 2
Selected bond lengths (Å) and bond angles (1) of compounds 1–4.
Compound 1
Zn(1)–N(2)
Zn(1)–O(2)#1
N(2)–Zn(1)–O(2)#1
O(2)#1–Zn(1)–O(2)
N(2)#1–Zn(1)–O(1)#1
Compound 2
2.101(3)
2.122(2)
91.87(10)
146.20(14)
100.72(11)
Zn(1)–O(1)#1
2.205(3)
79.60(17)
114.47(10)
150.12(10)
60.48(10)
N(2)–Zn(1)–N(2)#1
N(2)#1–Zn(1)–O(2)#1
N(2)–Zn(1)–O(1)#1
O(2)#1–Zn(1)–O(1)#1
2.3.5. Synthesis of [pb(NO3)(o-MAABA)(phen)]n (4)
Compound 4 was synthesized following a similar procedure in
1, except Pb(NO3)2 (16.56 mg, 0.05 mmol) as used (Scheme 1).
Colorless crystals of compound 4 were obtained from solvent
evaporation for a few days and isolated by filtration (Scheme 1).
Yield: 10.4 mg (32%). Anal. Calc. For C23H15N4O6Pb: C, 42.42; H,
2.31; N, 8.61. Found: C, 42.50; H, 2.38; N, 8.55. IR (KBr, cm−1): 3415
(b), 3050(w), 1978(w), 1672(w), 1622(m), 1585(s), 1515(s), 1423(s),
1384(m), 1349(w), 1144(m), 1103(m), 1070(w), 861(s), 784(w), 729
(s), 638(w).
Cd(1)–O(4)
Cd(1)–O(7)
Cd(1)–O(2)
Cd(1)–O(1)
2.222(3)
2.371(2)
2.282(2)
2.513(3)
106.90(11)
98.41(10)
154.34(10)
94.60(10)
127.40(9)
167.79(9)
53.91(8)
Cd(1)–O(5)
Cd(1)–O(8)
Cd(1)–O(1)#1
2.554(3)
2.264(3)
2.394(2)
2.554(3)
133.86(10)
87.74(10)
85.23(8)
81.44(10)
76.37(9)
78.44(9)
83.51(8)
Cd(1)–O(5)
O(4)–Cd(1)–O(8)
O(8)–Cd(1)–O(2)
O(8)–Cd(1)–O(7)
O(4)–Cd(1)–O(1)#1
O(2)–Cd(1)–O(1)#1
O(4)–Cd(1)–O(1)
O(2)–Cd(1)–O(1)
Compound 3
O(4)–Cd(1)–O(2)
O(4)–Cd(1)–O(7)
O(2)–Cd(1)–O(7)
O(8)–Cd(1)–O(1)#1
O(7)–Cd(1)–O(1)#1
O(8)–Cd(1)–O(1)
O(7)–Cd(1)–O(1)
3. Results and discussion
Pb(1)–N(4)
Pb(1)–N(5)
2.522(5)
2.615(6)
Pb(1)–O(1)
Pb(1)–O(2)
2.525(5)
2.640(5)
3.1. Experimental section
Pb(1)–N(2)
2.669(5)
Pb(1)–N(3)
2.780(5)
Preparations of these compounds were shown in Scheme 1. All
compounds were air stable and soluble in water but difficult to
dissolve in some common organic solvents such as THF, CHCl3,
toluene and so on. All compounds were confirmed by IR, Ele-
N(4)–Pb(1)–O(1)
O(1)–Pb(1)–N(5)
O(1)–Pb(1)s–O(2)
N(4)–Pb(1)–N(2)
N(5)–Pb(1)–N(2)
N(4)–Pb(1)–N(3)
N(5)–Pb(1)–N(3)
N(2)–Pb(1)–N(3)
Compound 4
76.49(16)
75.39(15)
50.43(14)
82.18(16)
132.99(16)
73.49(16)
77.69(16)
60.92(15)
N(4)–Pb(1)–N(5)
N(4)–Pb(1)–O(2)
N(5)–Pb(1)–O(2)
O(1)–Pb(1)–N(2)
O(2)–Pb(1)–N(2)
O(1)–Pb(1)–N(3)
O(2)–Pb(1)–N(3)
64.53(17)
73.78(17)
117.58(15)
129.67(15)
80.04(14)
146.08(15)
131.53(15)
−
mental Analyses and TGA. According to IR spectra, the NO3
vibration bands appeared at about 1070 cm−1 for 4, the asym-
metric stretching carboxyl group bands at about 1620 and
1381 cm−1 for 1, 1617 and 1364 cm−1 for 2, 1617 and 1344 cm−1
for 3, 1622 and 1384 cm−1 for 4.
Pb(1)–O(1)
Pb(1)–O(2)
2.468(4)
2.508(5)
Pb(1)–N(3)
Pb(1)–N(2)
2.488(5)
2.620(6)
Pb(1)–O(6)
2.692(5)
O(1)–Pb(1)–N(3)
N(3)–Pb(1)–O(2)
N(3)–Pb(1)–N(2)
O(1)–Pb(1)–O(6)
O(2)–Pb(1)–O(6)
80.60(16)
77.91(17)
64.89(17)
126.97(15)
76.11(14)
3.2. Description of crystal structures
O(1)–Pb(1)–O(2)
O(1)–Pb(1)–N(2)
O(2)–Pb(1)–N(2)
N(3)–Pb(1)–O(6)
N(2)–Pb(1)–O(6)
52.56(15)
75.10(17)
119.76(15)
76.11(16)
131.35(16)
3.2.1. Zn(o-MAABA)2(phen) (1, mononuclear structure)
Compound 1 is a mononuclear compound in which the six-
coordinated central zinc atom is connected by two nitrogen atoms
from the 1, 10-Phen ligand, four oxygen atoms of two carboxylate
from two o-MAABA anions into a distorted octahedral geometry
Symmetry transformations used to generate equivalent atoms for 1: #1−x+1, y, −z
+1/2; for 2: #1−x+2, −y, −z; for 4: #1−x, −y, −z+1 #2 x−1, y+1, z.
Scheme 1. Synthesis route of compounds 1–4.

4
H.-X. Chen et al. / Journal of Solid State Chemistry 203 (2013) 1–7
Fig. 1. (a) Local coordination environments of Zn in compound 1 (#1 −x+1, y, −z+1/2, H atoms were omitted for clarity); (b) Packing of compound 1 (#1 −x+1, y, −z+1/2,
H atoms were omitted for clarity); (c) π–π stacking of compound 1 (#1 −x+1, y, −z+1/2, H atoms were omitted for clarity).
Fig. 2. (a) Local coordination environments of Cd in compound 2 (#1 −x+1, y, −z+1/2, H atoms were omitted for clarity); (b) Packing of compound 2 (#1 −x+1, y, −z+1/2,
H atoms were omitted for clarity); (c) Hydrogen bonds in compound 2 (#1 −x+1, y, −z+1/2).
(Fig. 1(a)). The average bond of Zn–N and Zn–O distance are 2.101
(3) Å and 2.164(3) Å, respectively. Two o-MAABA anions act as
bidentate ligand with −1 valence, and its carboxyl group acts as a
(μ1,3-bridge) mode, chelating with the metal Zn atom (Fig. 1(a)).
The coordinated Phen ligands was interacted with the nearby
Phen ligand respectively to form a 3D supramolecular structure
(Fig. 1(b)). The π–π stacking between two closest Phen ligands of
nearby units is 3.537(2) Å (Fig. 1(c)).
distances [18]. The structure of compound 2 extends into 3D
supramolecular array through hydrogen bonds formed from the
O atoms of coordinated water molecule and the N atoms of
uncoordinated amide groups (Fig. 2(c)). It should be mentioned
that the π–π stacking between o-MAABA ligand is weak and
neglected.
3.2.3. {[ Pb2Cl2(o-MAABA)2(phen)4] ꢀ 2H2O } [(3 ꢀ 2H2O), binuclear
structure]
3.2.2. [Cd(o-MAABA)2 ꢀ 2H2O]2 (2, binuclear structure)
The structural analysis shows that compound 2 crystallizes in
space group P-1, with a binuclear structure. In this compound, two
Cd atoms are bridged by two oxygen atoms and the coordination
sphere of one Cd atom is a pentagonal bipyramid, completed by
seven oxygen atoms from two H2O molecules and five oxygen
atoms from three o-MAABA ions (Fig. 2(a)). The carboxylate
groups of o-MAABA act as μ1,3-carboxylate and μ1,1,3-carboxylate
modes. The bond distance of Cd–O(H2O) is 2.518(11) Å, and the
average bond distance of Cd–O(carboxyl) is 2.566 Å (Table 2),
which falls within the range of reported Cd–O(carboxyl) bond
Single X-ray structure analysis reveal that compound 3 contains
one Pb atom, two coordinated chloride anions, one ligand
o-MAABA, two 1, 10-Phen molecules, two free water molecules
in the asymmetric unit. As shown in Fig. 3(a), the lead(II) center
shows a eight-coordinated geometry with two O atoms from
carboxyl of one o-MAABA anion and four N atoms of two 1, 10-
Phen molecules, two bridged chloride anions. There are two μ-Cl
single bridges between the two closest Pb atoms. o-MAABA ligand
shows a μ1,3-carboxylate group chelating with the Pb(II) atom
(Fig. 3(b)). The coordinated Phen ligands interacted with the

H.-X. Chen et al. / Journal of Solid State Chemistry 203 (2013) 1–7
5
Fig. 3. (a) Local coordination environments of Pb in compound 3 (H atoms were omitted for clarity); (b) Packing of compound 3 (H atoms were omitted for clarity); (c) π–π
stacking of compound 3 (H atoms were omitted for clarity).
Fig. 4. (a) Local coordination environments of Pb in compound 4 (#1 −x, −y, −z+1 #2 x−1, y+1, z, H atoms were omitted for clarity); (b) Perspective view showing the 1D
chain along c axis (#1 −x, −y, −z+1 #2 x−1, y+1, z, H atoms were omitted for clarity); (c) π–π stacking of compound 4 (#1 −x, −y, −z+1 #2 x−1, y+1, z, H atoms were omitted for
clarity).
nearby Phen ligand to form a 3D supramolecular structure with
the closest π–π stacking of 3.643(4) Å (Fig. 3(c)).
(2-pyridyl)-1,2,4,5-tetrazine), the coordinated NO3− anions play an
important role in stabilizing the infinite structure [20]. The NO3
−
ions adopt tridentate coordinated mode (μ1,3,4-bridge) with Pb
−
atoms. Therefore, Pb atoms link each other via two NO3 bridges
3.2.4. [Pb(NO3)(o-MAABA)(phen)]n (4, 1D chain)
Compound 4 shows an infinite chain with space group P-1.
Its asymmetric unit includes one lead atom, a NO3 ion, one 1,
10-Phen molecule and an o-MAABA anion. The Pb atom adopts
distorted [PbN2O6] geometry, ligated by two nitrogen atoms from
1, 10-Phen molecule and two oxygen atoms from carboxyl group
and two o-MAABA bridges alternatively forming an infinite chain
along c axis (Fig. 4(b)). The 1, 10-Phen molecule only acts as a
chelating ligand to coordinate with the center metal ion. The π–π
stacking of two closest o-MAABA ligands is 3.62 Å and that of
closest of Phen ligands is 3.89 Å, constructing the 3D supramole-
cular structure (Fig. 4(c)).
-
−
of the ligand o-MAABA, two oxygen atoms from NO3 (Fig. 4(a)).
o-MAABA acts as a bridge between two Pb atoms, in which its
carboxyl group acts as a chelating group and the O atom from
amide group links the closest Pb atom. Similar with the reported
cases of [Pb(4-bpdh)(NO3)2]n (4-bpdh¼2,5-bis(4- pyridyl)-3,
4-diaza-2,4-hexadiene) [19], and [Ag(bptz)(NO3)] (bptz¼3,6-bis
3.3. Structural diversity of Compounds 1–4
Compounds 1–4 show different coordination features from
mononuclear structure to binuclear structure and 1D chain. Three
coordination modes of o-MAABA are adopted in all compounds.

6
H.-X. Chen et al. / Journal of Solid State Chemistry 203 (2013) 1–7
Scheme 2. Coordination modes of o-methacrylamidobenzoic acid (o-MAABA).
As depicted in Scheme 2, compounds 1 and 3 adopt coordination
mode a, compound 2 adopts coordination mode b and compound
4 adopts coordination mode c, respectively. It is clear that the
second ligand Phen affects the coordination mode of o-MAABA. In
addition, anions participated in the coordination also affect the
coordination mode of o-MAABA. For instance, in compound 3,
chloride anion as the second anion participated in the structural
architectures; however amide group did not coordinate with the
metal center. Differently, in compound 4, nitrate ion acted as a
second anion, and amide group coordinated with the metal center.
3.4. TGA study
The thermal stabilities of compounds 1–3 were assessed by
TGA measurement (See SI, Fig. S-1). The thermal stability of 1 is
relatively high, with a decomposition temperature of approxi-
mately 300 1C, which can be ascribed to the loss of all organics and
chloride. The final residue of 1 is 11.7% at 799 1C, assigned to ZnO
(calculated value, 12.39%).
The thermal decomposition of 2 is characterized by a dehydra-
tion step (8.3%) from 22 to 186 1C, which is probably due to the
compound obtained from water solution without further dryness
and free water molecule leaves from material surface [21]. The
following step, from 186 to 456 1C, corresponds to the decomposi-
tion of all organics. The residue (19.29 %) is consistent with the
calculated value (20.9%), assuming CdO as the final products.
The thermal decomposition of 3 is characterized by a dehydra-
tion step from 50 to 297 1C, which is probably due to the
compound obtained from water solution without further dryness
and free water molecule leaves from material surface [21]. The
final residue of 3 is 18.6% at 800 1C (calculated 17%), assigned to
PbCl2.
Fig. 5. (a) The emission spectra of o-MAABA, 1, 2 and 4 in DMF solution; (b) Solid-
state emission spectra of o-MAABA, 1, 2 and 4 at room temperature.
3.5. PXRD results
Fig. S-3), indicating an energy transfer from Phen to o-MAABA. The
emissions of compound o-MAABA, 1, 2 and 4 at the solid state
were shown in Fig. 5(b). The emission of o-MAABA at solid state
was observed at about 450 nm, compared to that in solution, the
red-shift of emission was assigned to the molecular aggregates and
stacking. For 1, upon excitation at 352 nm, it exhibited observable
photoluminescence with emission maxima peaks at 524 nm. The
red-shift is about 74 nm compared to that of ligand itself and
ascribed to Ligand–Metal Charge Transfer (LMCT) [23,24]. For 2,
upon excitation at 340 nm, the emission maximum is at 454 nm,
which is similar to that of the ligand o-MAABA. For 4, upon
excitation at 390 nm, the emission maximum is at 479 and
584 nm. The emission at 479 nm might be ascribed to the LMCT,
while the 584 nm peak is in consistent with the formation of
excimer due to the molecular stacking in solid state. From the
above results in this case, the emission wavelength can be tuned
by different center ions due to their different affinity with organic
ligand. Due to the coordination between metal ion and organic
ligand, the ordered array in crystalline inclined to the formation of
excimers and resulted in the red-shift of emission wavelength.
Powder X-ray diffraction (PXRD) patterns of compounds 1–4
were in agreement with the simulated patterns from the single-
crystal X-ray data (See SI, Fig. S-2). It indicates that the crystal
structures are truly representative of the bulk materials. The
differences in intensity are due to the preferred orientation of
the powder samples.
3.6. Photoluminescent properties
The photoluminescent properties of compounds 1–4 and the
free o-MAABA ligand have been investigated in DMF solution and
the solid state at room temperature, respectively. The emission of
compound 3 is too weak to be observed, assigned to the quenching
of chloride anion [22]. The emission bands in DMF solution are all
similar with that of the free ligand o-MAABA which is originated
from the π –π transition of ligand (Fig. 5(a)). It is probably due to
n
the dissociation of metal compounds in polar solution. However
there is also only one emission band shown from a mixture of
Phen and o-MAABA in DMF solution without metal ions (See SI,

H.-X. Chen et al. / Journal of Solid State Chemistry 203 (2013) 1–7
7
4. Conclusion
(b) X.X. Xu, Y. Ma, E.B. Wang, J. Solid State Chem. 180 (2007) 3136;
(c) Y.W. Hu, G.H. Li, X.M. Liu, B. Hu, M.H. Bi, L. Gao, Z. Shi, S.H. Feng,
CrystEngComm 10 (2008) 888.
A series of coordination compounds based on a new o-metha-
crylamidobenzoic acid (o-MAABA) ligand and N-donor (1, 10-
Phen) ligand have been successfully synthesized. These com-
pounds show versatile coordination features from mononuclear
structure to binuclear structure and 1D chain. The structural
differences in the compounds were attributed to the different
coordination modes of o-MAABA ligand, the coordination num-
bers of the central metals and the second ligand (1, 10-Phen)
involved. The photoluminescent properties of the compounds 1, 2
and 4 in the solid state are also discussed. The PL is highly affected
by the molecular stacking. For instance in compound 4, the π–π
stacking results in the formation of excimer and red shift of
emission band.
[4] (a) L. Hou, Y.Y. Lin, X.M. Chen, Inorg. Chem. 47 (2008) 1346;
(b) Z.F. Tian, J.G. Lin, Y. Su, L.L. Wen, Y.M. Liu, H.Z. Zhu, Q.J. Meng, Cryst.
Growth Des. 7 (2007) 1863;
(c) M. Du, X.J. Jiang, X.J. Zhao, Inorg. Chem. 46 (2007) 3984.
[5] (a) D.R. Xiao, E.B. Wang, H.Y. An, Y.G. Li, L. Xui, Cryst.Growth Des. 7 (2007)
506;
(b) G.B. Che, C.B. Liu, B. Liu, Q.W. Wang, Z.L. Xu, CrystEngComm 10 (2008) 184.
[6] (a) J. Wang, Z.J. Lin, Y.C. Ou, N.L. Yang, Y.H. Zhang, M.L. Tong, Inorg. Chem.
47 (2008) 190;
(b) X.Y. Wang, S.C. Sevov, Inorg. Chem. 47 (2008) 1037;
(c) Q.G. Zhai, C.Z. Lu, X.Y. Wu, S.R. Batten, Cryst. Growth Des. 7 (2007) 2332.
[7] (a) L.L. Wen, D.B. Dang, C.Y. Duan, Y.Z. Li, Z.F. Tian, Q.J. Meng, Inorg. Chem.
44 (2005) 7161;
(b) H.L. Gao, L. Yi, B. Zhao, X.Q. Zhao, P. Cheng, D.Z. Liao, S.P. Yan, Inorg. Chem.
45 (2006) 5980;
(c) T.K. Prasad, M.V. Rajasekharan, Polyhedron 26 (2007) 1364.
[8] J. Xia, B. Zhao, H.S. Wang, W. Shi, Y. Ma, H.B. Song, P. Cheng, D.Z. Liao, S.P. Yan,
Inorg. Chem. 46 (2007) 3450.
[9] (a) R.Q. Fang, X.M. Zhang, Inorg. Chem. 45 (2006) 4801;
(b) W.G. Lu, J.Z. Gu, L. Jiang, M.Y. Tan, T.B. Lu, Cryst. Growth Des. 8 (2008) 192.
[10] (a) Y.Q. Guo, B.P. Yang, J.L. Song, J.G. Mao, Cryst. Growth Des. 8 (2008) 600;
(b) J Wang, Z.J. Lin, Y.C. Qu, N.L. Yang, Y.H. Zhang, M.L. Tong, Inorg. Chem.
47 (2008) 190.
[11] (a) X.L. Wang, C. Qin, E.B. Wang, L. Xu, Cryst. Growth Des. 6 (2006) 2061;
(b) Z.F. Chen, Z.L. Zhang, Y.H. Tan, Y.Z. Tang, H.K. Fun, Z.Y. Zhou, B.F. Abrahams,
H. Liang, CrystEngComm 10 (2008) 217.
[12] (a) Y.L. Yao, L. Xue, Y.X. Che, J.M. Zheng, Cryst. Growth Des. 9 (2009) 606;
(b) X.M. Zhang, T. Jiang, H.S. Wu, M.H. Zeng, Inorg. Chem. 48 (2009) 4536;
(c) J.Y. Zheng, A.L. Cheng, Q. Sun, Q. Yue, E.Q. Gao, Cryst. Growth Des.
10 (2010) 2908;
Supplementary data
TGA curve of compounds 1–3, XRD for compounds 1–4, and
hydrogen bond geometries in the crystal structure of 4 are
provided in Supplementary Information.
Additional crystallographic data have been deposited at the
Cambridge Crystallographic Data Centre, CCDC reference numbers
are 830665 for 1, 917478 for 2, 917477 for 3, 826685 for 4. The data
can be obtained free of charge from www.ccdc.cam.ac.uk/conts/
retrieving.html (or from CCDC, 12 Union Road, Cambridge CB2 1EZ,
UK; fax:+ 44 1223 336 033; e-mail: deposit@ccdc.cam.ac.uk.)
(d) P. Cui, Z. Chen, D.L. Gao, B. Zhao, W. Shi, P. Cheng, Cryst. Growth Des.
10 (2010) 4370.
[13] (a) S.T. Zheng, T. Wu, J. Zhang, M. Chow, R.A. Nieto, P.Y. Feng, X.H. Bu, Angew.
Chem. Int. Ed. 49 (2010) 5362;
(b) P.K. Allan, B. Xiao, S.J. Teat, J.W. Knight, R.E. Morris, J. Am. Chem. Soc. 132
(2010) 3605;
Acknowledgments
(c) S. Bureekaew, W. Sato, R. Matsuda, Y. Kubota, R. Hirose, J. Kim, K. Kato,
M. Takata, S. Kitagawa, Angew. Chem. Int. Ed. 49 (2010) 7660.
[14] S.C. Manna, E. Zangrando, M.G.B. Drew, J. Ribas, N.Ray Chaudhuri, Eur. J. Inorg.
Chem. (2006) 481.
[15] (a) E.Y. Choi, Y. Kwon, Inorg. Chem. 44 (2005) 538;
(b) Z. Lin, F. Jiang, L. Chen, D. Yuan, M. Hong, Inorg. Chem. 44 (2005) 73;
(c) A.V. Lee, L.L. Schafer, Eur. J. Inorg. Chem. 16 (2007) 2243;
(d) D.C. Leitch, J.D. Beard, R.K. Thomson, V.A. Wright, B.O. Patrick, L.L. Schafer,
Eur. J. Inorg. Chem. (2009) 2691.
The authors thank the Chinese Natural Science Foundation
(21071105 and 21176164) and the project for Environmental
Protection in Suzhou (201102).
Appendix A. Supporting information
[16] (a) X.M. Chen, G.F. Liu, Chem. Eur. J. 8 (2002) 4811;
(b) G.F. Liu, B.H. Ye, Y.H. Ling, X.M. Chen, Chem. Commun. (2002) 1442.
[17] G.M. Sheldrick, Acta Crystallogr. A64 (2008) 112.
[18] (a) M.L. Zhang, D.S. Li, J.J. Wang, F. Fu, M. Du, K. Zou, X.M. Gao, Dalton Trans.
(2009) 5355;
Supplementary data associated with this article can be found in
the online version at http://dx.doi.org/10.1016/j.jssc.2013.03.055.
(b) D.S. Liu, Y. Sui, W.T. Chen, J.G. Huang, J.Z. Chen, C.C. Huang, J. Solid State
Chem. 196 (2012) 161.
References
[19] L. Hashemi, A. Morsali, Cryst. Eng. Commun. 14 (2012) 8349.
[20] K. Chainok, S.M. Neville, C.M. Forsyth, W.J. Gee, K.S. Murraya, S.R. Batten, Cryst.
Eng. Commun. 14 (2012) 3717.
[1] (a) X.L. Wang, C. Qin, E.B. Wang, Z.M. Su, L X, S.R. Batten, Chem. Commun.
(2005) 4789;
[21] X.R. Hao, X.L. Wang, Z.M. Su, K.Z. Shao, Y.H. Zhao, Y.Q. Lan, Y.M. Fu, Dalton
Trans. (2009) 8562.
(b) C.D. Wu, W. Lin, Angew. Chem. Int. Ed. 46 (2007) 1075;
(c) M. O’Keeffe, M.A. Peskov, S.J. Ramsden, O.M. Yaghi, Acc. Chem. Res.
41 (2008) 1782;
[22] (a) K.N. Jayanta, J.B. Baruah, New J. Chem. (2013), http://dx.doi.org/10.1039/
c3nj00034f;
(b) J.W. Steed, Chem. Soc. Rev. 38 (2009) 506.
(d) J.J. Perry, J.A. Perman, M.J. Zaworotko, Chem. Soc. Rev. 38 (2009) 1400.
[2] (a) S. Delgado, P.J. Sanz Miguel, J.L. Priego, R. Jimenez-Aparicio, C.J. Gomez-
Garcia, F. Zamora, Inorg. Chem. 47 (2008) 9128;
[23] (a) H.A. Habib, A. Hoffmann, H.A. HÖppe, C. Janiak, Dalton Trans. (2009) 1742;
(b) X.H. Jin, J.K. Sun, L.X. Cai, J. Zhang, Chem. Commun. 47 (2011) 2667;
(c) F.P. Huang, J.B. Lei, Q. Yu, H.D. Bian, S.P. Yan, Polyhedron 34 (2012) 129;
(d) X.R. Jiang, H.Y. Yuan, Y.L. Feng, J. Solid State Chem. 191 (2012) 181.
[24] (a) O. Kahn, Acc．Chem．Res 33 (2000) 647;
(b) S.C. Xiang, W. Zhou, J.M. Gallegos, Y. Liu, B. Chen, J. Am. Chem. Soc. 131
(2009) 12415;
(c) B.V. Harbuzaru, A. Corma, F. Rey, J.L. Jorda, D. Ananias, L.D. Carlos, J. Rocha,
Angew. Chem. Int. Ed. 48 (2009) 6476.
(b) Z.N. Chen, N. Zhao, Y. Fan, J. Ni, Coord. Chem. Rev. 253 (2009) 1;
(c) F. Guo, B.Y. Zhu, G.L. Xu, M.M. Zhang, X.L. Zhang, J. Zhang, J. Solid State
Chem. 199 (2013) 42.
[3] (a) R.H. Wang, Y.F. Zhou, Y.Q. Sun, D.Q. Yuan, L. Han, B.Y. Lou, B.L. Wu,
M.C. Hong, Cryst. Growth Des. 5 (2005) 251;