Hydrothermal syntheses and crystal structures of five complexes with 3,5-dinitrosalicylate and N-donor ligand: Helical chains, 2D network and extended 3D structures

Article abstract of DOI:10.1016/j.molstruc.2007.06.031

Five complexes with 3,5-dinitrosalicylate (3,5-(NO₂)₂sal) and N-donor ligand, [Cd{3,5-(NO₂)₂sal}(phen)(H₂O)]_n (1), Ni{3,5-(NO₂)₂sal}(phen)(H₂O)₂ (2), [Co{3,5-(NO₂)₂sal}(4,4′-bipy)(H₂O)·(H₂O)]_n (3), [Co{3,5-(NO₂)₂sal}(phen)]_n (4) and [Zn{3,5-(NO₂)₂sal}(phen)]_n (5), have been synthesized by hydrothermal reactions and characterized by single crystal X-ray analysis, where phen = 1,10-phenanthroline and 4,4′-bipy = 4,4′-bipyridine. There are one-dimensional left- and right-handed helical chains in complexes 1, 4 and 5, an extended 3D structure in 2, and a 2D rectangular grid-like network in 3. The C-H···O hydrogen bonds lead to the formation of 3D supramolecular structures in the five title complexes. The fluorescent spectra study show that compounds 1 and 5 exhibit weak fluorescent emission in the solid state at room temperature.

Full text of DOI:10.1016/j.molstruc.2007.06.031

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Journal of Molecular Structure 876 (2008) 154–161
www.elsevier.com/locate/molstruc
Hydrothermal syntheses and crystal structures of five complexes
with 3,5-dinitrosalicylate and N-donor ligand: Helical chains,
2D network and extended 3D structures
a,
a
De-Cai Wen a,b, Shi-Xiong Liu *, Min Lin
a
Department of Chemistry, Fuzhou University, Fuzhou 350002, PR China
Department of Chemistry, Longyan University, Longyan 364000, PR China
b
Received 2 March 2007; received in revised form 14 June 2007; accepted 16 June 2007
Available online 5 July 2007
Abstract
Five complexes with 3,5-dinitrosalicylate (3,5-(NO2)2sal) and N-donor ligand, [Cd{3,5-(NO2)2sal}(phen)(H2O)]n (1), Ni{3,5-
(NO2)2sal}(phen)(H2O)2 (2), [Co{3,5-(NO2)2sal}(4,40-bipy)(H2O)Æ(H2O)]n (3), [Co{3,5-(NO2)2sal}(phen)]n (4) and [Zn{3,5-(NO2)2sal}
(phen)]n (5), have been synthesized by hydrothermal reactions and characterized by single crystal X-ray analysis, where phen = 1,10-phe-
nanthroline and 4,40-bipy = 4,40-bipyridine. There are one-dimensional left- and right-handed helical chains in complexes 1, 4 and 5, an
extended 3D structure in 2, and a 2D rectangular grid-like network in 3. The C–HÆÆÆO hydrogen bonds lead to the formation of 3D
supramolecular structures in the five title complexes. The fluorescent spectra study show that compounds 1 and 5 exhibit weak fluores-
cent emission in the solid state at room temperature.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Coordination polymer; Helical chain; 3,5-Dinitrosalicylic acid; Hydrogen bond; Crystal structure
1. Introduction
supramolecular architectures based on bipy-like and car-
boxylate ligands have been reported [19]. Some non-coor-
dinated functional groups such as NO2, NH2, etc. are
well known to form robust and strong hydrogen bond,
the syntheses of metal–organic supramolecular assemblies
employing organic ligands with NO2 groups are limited
[20,21]. As far as the reaction pathways, recent plentiful
practice has prove that the hydrothermal synthesis is a
promising technique in preparing metal complexes with
novel structures and special properties, which are difficult
to obtain by routine synthetic methods [22–25].
The self-assembly in metallacrowns based on 3d-series
metals with N-acyl salicylhydrazides [7,26,27] has been
reported in our group. In an extension of this research,
3,5-dinitrosalicylate (3,5-(NO2)2sal) is selected as a ligand
to form coordination polymers. Because numerous
coordination polymers with salicylic acid were found to
display diverse structure types, but only a few com-
plexes with 3,5-(NO2)2sal are reported [28–32]. Further,
Coordination polymers continue to be extensively stud-
ied because of not only for their intriguing structural fea-
tures, but also for their potential applications such as
magnetism, catalysis, chirality, luminescence, non-linear
optics, molecular recognition and sorption [1–5]. Salicylic
acid and its substituted derivatives continue to attract
attention because of its versatile coordination modes [6–
10] and biological applications [11–13]. Salicylate anion
can also exist in solid state as phenolato anion or as carb-
oxylato anion and/or as dianion. There has been continu-
ous interest in the influence of deprotonation degree for
salicylate on the structures of related complexes [14–18].
Hydrogen bond plays an important role in forming
supramolecular architectures. A lot of hydrogen-bonded
*
Corresponding author.
E-mail address: shixiongliu@yahoo.com (S.-X. Liu).
0022-2860/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2007.06.031

D.-C. Wen et al. / Journal of Molecular Structure 876 (2008) 154–161
155
1,10-phenanthroline and 4,40-bipyridine have also been
chosen as a co-ligand, not only they can bind to metal ion
to form coordination polymers, but also they can also act as
hydrogen bond donors to form weak C–HÆÆÆO hydrogen
bonds with the NO2 groups of 3,5-(NO2)2sal ligand [19,33].
Herein, we report hydrothermal syntheses and crystal struc-
tures of five complexes with mixed ligands (3,5-(NO2)2sal
and N-donor ligand). These complexes are [Cd{3,5-(NO2)2sal}
(phen)(H2O)]n (1), Ni{3,5-(NO2)2sal}(phen)(H2O)2 (2),
[Co{3,5-(NO2)2sal}(4,40-bipy)(H2O)Æ(H2O)]n (3), [Co{3,5-
(NO2)2sal}(phen)]n (4) and [Zn{3,5-(NO2)2sal}(phen)]n (5)
(phen = 1,10-phenanthroline, 4,40-bipy = 4,40-bipyridine).
based on Co. Anal. Found: C, 42.80; H, 2.80; N, 11.64%.
Calc. for C17H14N4O9Co (Mr = 477.25): C, 42.78; H,
2.96; N, 11.74%.
2.4. Synthesis of [Co{3,5-(NO2)2sal}(phen)]n (4)
The same synthetic procedure as that for 1 was used
except that Cd(NO3)2Æ4H2O was replaced by Co(OA-
c)2Æ4H2O. The green prism-like crystals of 4 were synthe-
sized in 66% yield based on Co. Anal. Found: C, 49.08;
H, 2.02; N, 11.91%. Calc. for C19H10N4O7Co (Mr =
465.24): C, 49.05; H, 2.17; N, 12.04%.
2. Experimental
2.5. Synthesis of [Zn{3,5-(NO2)2sal}(phen)]n (5)
All of the chemicals were obtained from commercial
sources and were used without further purification. Ele-
mental analyses were conducted on a Perkin-Elmer 2400
CHN elemental analyzer. IR spectra were recorded on a
Nicolet 360 FT-IR spectrometer with KBr pellets in
the 4000–400 cmꢀ1 region. Thermogravimetric analysis
(TGA) of complex 1 was obtained on NETZSCH STA
449C thermogravimetric analyzer, carried out under N2
with a heating rate of at 10 ꢁC minꢀ1. Fluorescence spec-
troscopy was performed on a Perkin-Elmer LS 55 lumines-
cence spectrometer.
The same synthetic procedure as that for 1 was used
except that Cd(NO3)2Æ4H2O was replaced by Zn(NO3)2Æ
6H2O. The colorless chunk-like crystals of 5 were obtained
in 80% yield based on Zinc. Anal. Found: C, 48.43; H, 2.03;
N, 11.68%. Calc. for C19H10N4O7Zn (Mr = 471.68): C,
48.38; H, 2.14; N, 11.88%.
2.6. X-ray crystallography
X-ray diffraction measurements of the five title com-
plexes were carried out at 293 K on a Rigaku R-AXIS
RAPID Weissengberg IP diffractometer with graphite
˚
2.1. Synthesis of [Cd{3,5-(NO2)2sal}(phen)(H2O)]n (1)
monochrocmated Mo Ka radiation (k = 0.71073 A). The
structures were solved by direct methods (SHELXTL-97)
and refined on F2 by full-matrix least-squares techniques.
The crystallographic data of 1–5 are summarized in
Table 1. The selected bond lengths and angles for 1–5 are
listed in Table 2.
A mixture of Cd(NO3)2Æ4H2O (0.1 mmol), 1,10-phenan-
throline (0.1 mmol), 3,5-dinitrosalicylic acid (0.2 mmol)
and distilled water (10 ml) with pH value adjusted to 7
by addition of 1 M NaOH solution was put into a Tef-
lon-lined autoclave (20 ml) and then heated at 180 ꢁC for
72 h. Yellow block-like crystals of 1 were obtained with
25% yield based on Cd. Anal. Found: C, 42.58; H, 2.15;
N, 10.35%. Calc. for C19H12N4O8Cd (Mr = 536.73): C,
42.52; H, 2.25; N, 10.44%.
3. Result and discussion
3.1. Structural description of [Cd{3,
5-(NO2)2sal}(phen)(H2O)]n (1)
2.2. Synthesis of Ni{3,5-(NO2)2sal}(phen)(H2O)2 (2)
The X-ray diffraction analysis reveals that complex 1
exhibits a helical chain structure consisting of Cd{3,5-
(NO2)2sal}(phen)(H2O) entities. As shown in Fig. 1, each
Cd(II) atom is coordinated by two N atoms from one che-
lating phen ligand, three O atoms (O2, O3 and O1A) from
two 3,5-(NO2)2sal ligands and one coordinated water mol-
ecule O8 atom, forming a distorted octahedron. The Cd–N
The same synthetic procedure as that for 1 was used
except that Cd(NO3)2Æ4H2O was replaced by Ni(OA-
c)2Æ2H2O. Yellow chip-like crystals of 2 were synthesized
with 30% yield based on Ni. Anal. Found: C, 45.60; H,
2.68; N, 11.12%. Calc. for C19H14N4O9Ni (Mr = 501.05):
C, 45.55; H, 2.82; N, 11.18%.
˚
bond lengths are 2.338(3) and 2.350(3) A. The Cd–O(3,5-
˚
(NO2)2sal) bond lengths are from 2.243(2) to 2.286(2) A,
˚
2.3. Synthesis of [Co{3,5-(NO2)2sal}(4,
40-bipy)(H2O)Æ(H2O)]n (3)
while Cd–O8(water) bond length is 2.334(2) A.
Every 3,5-(NO2)2sal ligand adopts a chelating–bridging
mode. Each 3,5-(NO2)2sal bridging ligand is not only coor-
dinated to one Cd(II) atom via its two oxygen atoms (phe-
nolate oxygen O3 and carboxylate oxygen O2), but also
coordinated to the other Cd(II) atom via carboxylate oxy-
gen O1 atom (Fig. 2a). Therefore, the adjacent Cd atoms
are bridged through the carboxylate CO2 group to obtain
a chain along the a axis (see Fig. 2a), the CdÆÆÆCd distance
A mixture of Co(OAc)2Æ4H2O (0.1 mmol), 4,40-bipy
(0.1 mmol), 3,5-dinitrosalicylic acid (0.2 mmol) and dis-
tilled water (10 ml) with the pH value adjusted to 7 by addi-
tion of 1 M NaOH solution was put into a Teflon-lined
autoclave (20 ml) and then heated at 180 ꢁC for 72 h,
brown chunk-like crystals of 3 were obtained in 33% yield

156
D.-C. Wen et al. / Journal of Molecular Structure 876 (2008) 154–161
Table 1
Crystallographic data in complexes 1–5
Compound
1
2
3
4
5
Formula
C19H12N4O8Cd
536.73
Orthorhombic
P bca
7.926(2)
21.268(6)
21.887(6)
90
90
90
3689(2)
8
1.933
C19H14N4O9Ni
501.05
Triclinic
C17H14N4O9Co
477.25
Monoclinic
P21/c
11.415(4)
8.648(3)
19.142(9)
90
94.76(1)
90
C19H10N4O7Co
465.24
Monoclinic
P21/n
12.487 (6)
7.944 (3)
18.575(6)
90
105.09(1)
90
C19H10N4O7Zn
471.68
Monoclinic
P21/n
12.3182(4)
8.0999(5)
18.4896(9)
90
104.434(2)
90
Formula weight
Crystal system
Space group
ꢀ
P1
˚
a (A)
7.359(2)
11.041(2)
12.551(3)
69.66(3)
88.24(3)
85.78(3)
953.6(3)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
1883 (1)
4
1.683
1779(1)
4
1.737
1786.6(2)
4
1.754
Z
Dcalc (g cmꢀ3
T (K)
)
1.745
293(2)
293(2)
293(2)
293(2)
293(2)
Color
Shape
Yellow
Block
0.15 · 0.25 · 0.28
1.246
Yellow
Chip
0.05 · 0.20 · 0.35
1.084
Brown
Green
Prism
0.10 · 0.15 · 0.59
1.021
940
Colorless
Chunk
0.10 · 0.15 · 0.10
1. 431
Chunk
0.10 · 0.10 · 0.25
0.974
Dimension (mm)
l (mmꢀ1
F (000)
)
2128
512
972
952
h
min, hmax (ꢁ)
3.17, 27.48
ꢀ10 fi 10
ꢀ27 fi 27
ꢀ27 fi 28
0.0512
3.04, 27.43
ꢀ9 fi 9
ꢀ14 fi 14
ꢀ16 fi 16
0.0545
3.09, 25.00
ꢀ12 fi 13
ꢀ9 fi 10
ꢀ22 fi 22
0.0870
3.07, 27.47
ꢀ16 fi 16
ꢀ8 fi 10
ꢀ23 fi 24
0.0435
1.80, 27.48
0 fi 15
0 fi 10
ꢀ24 fi 23
0.0487
hmin–max
kmin–max
lmin–max
Rint
No. of unique
No. of observed
No. variables
R
4214
3044
289
0.0316
4247
3250
354
0.0498
3314
2260
277
0.0587
4066
3153
278
0.0506
3979
2478
278
0.0475
wR
GOF
(Dp)max,min (e/A )
0.0723
1.035
0.468(ꢀ0.442)
0.1062
1.032
0.521(ꢀ0.672)
0.1371
1.056
0.786(ꢀ0.574)
0.1231
1.069
0.796, ꢀ0.621
0.1139
0.996
0.763(ꢀ0.424)
3
˚
˚
and Cd–Cd–Cd angle being 5.872(1) A and 84.90(1)ꢁ,
and two nitrogen atoms (N3 and N4) from chelating phen
ligand (Ni–N lengths 2.061(3) and 2.084(3) A) form the
˚
respectively.
There are
a
hydrogen bond O(8)–H(08A)ÆÆÆO(2A)
equatorial plane, while the two oxygen atoms (O8 and
O9) from two coordination water molecules occupy the
axial positions with Ni–O lengths of 2.125(3) and
2.151(3) A. Each 3,5-(NO2)2sal ligand is coordinated to
one Ni(II) atom only, coordinate mode of 3,5-(NO2)2sal
ligand being O,O0-chelating fashion.
As illustrated in Fig. 4 and Table 3, there are rich hydro-
gen bonds among the coordinated water molecules, the car-
boxylate groups and the NO2 groups of 3,5-(NO2)2sal
ligands in 2. These C–HÆÆÆO hydrogen bonds with oxygen
atoms (O4, O5, O6 and O7 from NO2 group) and the O–
HÆÆÆO hydrogen bonds between the water O–H group and
the carboxylate O1 atom connect the neighboring complex
molecules, resulting in an extended 2D layer network down
the a axis (see Figs. 4a and b).
between O(8)–H(08A) of coordinated water molecule
and carboxylate O(2) atom and a hydrogen bond O(8)–
H(08B)ÆÆÆO(6B) (O(6B) from a NO2 group). These hydro-
gen bonds connect the neighboring chains into a 2D
network structure along ac plane (Fig. 2a). There are
two kinds of parallel helices correspondingly, one is
right-handed helical chain (Fig. 2(b1)) and the other is
left-handed helical chain (Fig. 2(b2)), they are parallel
to each other along the a-axis. It is noteworthy that
the major intermolecular force between the polymer
chains in 1 is the C–HÆÆÆO hydrogen bonds between the
phenyl hydrogens of phen ligands and the NO2 groups
of 3,5-(NO2)2sal ligands (see Supplementary Fig. S1 and
Table 3).
˚
All hydrogen bonds lead to the formation of three-
dimensional framework structures (Fig. 4c). The hydrogen
bonds based on NO2 groups play an important role in the
supramolecular formation of complex 2.
3.2. Structural description of Ni{3,
5-(NO2)2sal}(phen)(H2O)2 (2)
Complex molecule 2 comprises of one Ni(II) atom, one
3,5-(NO2)2sal ligand, one phen ligand and two coordinated
water molecules (Fig. 3).
3.3. Structural description of [Co{3,5-(NO2)2sal}(4,
40-bipy)(H2O)Æ(H2O)]n (3)
The coordination geometry around the Ni(II) atom is an
octahedron. Two oxygen atoms (O2 and O3) from 3,5-
(NO2)2sal ligand (Ni–O lengths 1.980(2) and 1.989(2) A),
Complex 3 exhibits a 2D rectangular grid-like network
structure. As illustrated in Fig. 5, Co1 atom is coordinated
˚

D.-C. Wen et al. / Journal of Molecular Structure 876 (2008) 154–161
157
Table 2
˚
Selected lengths (A) and Angles (ꢁ) for complexes 1–5
Compound 1
Cd(1)–O(3)
Cd(1)–O(8)
2.243(2)
2.334(2)
77.49(7)
100.76(9)
78.67(8)
125.02(9)
119.72(9)
Cd(1)–O(2)
Cd(1)–N(4)
2.276(2)
2.338(3)
83.18(8)
81.27(8)
147.84(8)
80.49(8)
71.19(9)
Cd(1)–O(1)A
Cd(1)–N(3)
2.286(2)
2.350(3)
154.56(8)
86.22(9)
98.89(9)
102.83(8)
148.07(9)
O(3)–Cd(1)–O(2)
O(2)–Cd(1)–O(8)
O(3)–Cd(1)–N(4)
O(1)A–Cd(1)–N(4)
O(3)–Cd(1)–N(3)
O(2)–Cd(1)–O(1)A
O(1)A–Cd(1)–O(8)
O(2)–Cd(1)–N(4)
O(1)A–Cd(1)–N(3)
N(4)–Cd(1)–N(3)
O(3)–Cd(1)–O(1)A1
O(3)–Cd(1)–O(8)
O(A)–Cd(1)–N(4)
O(2)–Cd(1)–N(3)
O(A)–Cd(1)–N(3)
Compound 2
Ni(1)–O(2)
Ni(1)–N(3)
O(2)–Ni(1)–O(3)
O(3)–Ni(1)–N(3)
O(3)–Ni(1)–N(4)
O(2)–Ni(1)–O(8)
N(3)–Ni(1)–O(8)
1.980(2)
2.061(3)
91.82(9)
174.2(1)
93.5(1)
Ni(1)–O(3)
Ni(1)–O(8)
1.989(2)
2.126(3)
91.5(1)
89.8(1)
89.7(1)
90.6(1)
90.2(1)
Ni(1)–N(4)
Ni(1)–O(9)
2.084(3)
2.151(3)
93.93(1)
174.7(1)
80.8(1)
O(3)–Ni(1)–O(9)
O(2)–Ni(1)–O(9)
N(3)–Ni(1)–O(9)
N(4)–Ni(1)–O(8)
N(4)–Ni(1)–O(9)
O(2)–Ni(1)–N(3)
O(2)–Ni(1)–N(4)
N(3)–Ni(1)–N(4)
O(3)–Ni(1)–O(8)
O(8)–Ni(1)–O(9)
89.5(1)
90.2(1)
88.8(1)
179.2(9)
Compound 3
Co(1)–O(2)
Co(1)–N(4)B
O(2)–Co(1)–O(1)A
O(1)A1–Co(1)–O(3)
O(1)A–Co(1)–O(8)
O(2)–Co(1)–N(4)B
O(3)–Co(1)–N(4)B
2.037(3)
2.177(4)
81.5(1)
166.3(1)
96.0(2)
Co(1)–O(1)A
Co(1)–N(3)
2.089(4)
2.184(4)
92.4(2)
87.4(1)
175.6(2)
94.3(2)
Co(1)–O(3)
Co(1)–O(8)
2.093(4)
2.117(4)
84.8(1)
177.1(2)
97.7(2)
O(2)–Co(1)–N(3)
O(3)–Co(1)–N(3)
N(4)B–Co(1)–N(3)
O(1)A–Co(1)–N(3)
O(8)–Co(1)–N(3)
O(2)–Co(1)–O(3)
O(2)–Co(1)–O(8)
O(3)–Co(1)–O(8)
O(1)A–Co(1)–N(4)B
O(8)–Co(1)–N(4)B
91.4(1)
95.0(2)
84.2(2)
89.8(1)
86.2(2)
Compound 4
Co(1)–O(3)
Co(1)–N(4)
O(3)–Co(1)–O(2)
O(3)–Co(1)–O(1)A
O(2)–Co(1)–O(1)A
1.976(2)
2.109(3)
90.28(9)
111.7(1)
108.9(1)
Co(1)–O(2)
Co(1)–N(3)
O(3)–Co(1)–N(4)
O(2)–Co(1)–N(4)
O(1)A–Co(1)–N(3)
2.003(2)
2.144(3)
92.7(1)
135.3(1)
83.4(1)
Co(1)–O(1)A
2.010(2)
111.2(1)
164.4(1)
88.53(9)
77.4(1)
O(1)A–Co(1)–N(4)
O(3)–Co(1)–N(3)
O(2)–Co(1)–N(3)
N(4)–Co(1)–N(3)
Compound 5
Zn(1)–O(1)A
Zn(1)–N(4)
O(1)A–Zn(1)–O(3)
O(1)A–Zn(1)–O(2)
O(3)–Zn(1)–O(2)
1.979(3)
2.139(3)
111.0(1)
109.5(1)
89.1 (1)
Zn(1)–O(2)
Zn(1)–N(3)
O(1)A–Zn(1)–N(3)
N(3)–Zn(1)–N(4)
O(2)–Zn(1)–N(4)
2.009(3)
2.137(3)
111.4(1)
77. 5(1)
89.6 (1)
Zn(1)–O(3)
1.988(3)
89.9 (1)
136.5(1)
88.2(1)
O(3)–Zn(1)–N(3)
O(2)–Zn(1)–N(3)
O(1)A–Zn(1)–N(4)
O(3)–Zn(1)–N(4)
160.1(1)
Symmetry code: 1 (A) x ꢀ 1/2, ꢀy + 1/2, ꢀz + 1. 3 (A) ꢀx + 1, y ꢀ 1/2, ꢀz + 3/2; (B) x ꢀ 1, y, z. 4 (A) ꢀx + 3/2, y + 1/2, ꢀz + 1/2. 5 (A) ꢀx + 1/2,
y ꢀ 1/2, ꢀz + 1/2.
by three oxygen atoms from two 3,5-dinitrosalicylate
The adjacent 2D fragments are further connected to each
other by C–HÆÆÆO hydrogen bonds between the phenyl
hydrogens of 4,40-bipy and the NO2 groups of 3,5-
(NO2)2sal ligands, resulting in a 3D framework structure
(Supplementary Fig. S2).
˚
ligands (Co–O lengths range 2.037(4)–2.094(7) A), two
nitrogen atoms from two 4,40-bipyridine ligands (Co–N
˚
lengths 2.177(4), 2.184(5) A) and one oxygen atom from
˚
coordination water (Co–O8 lengths 2.116(4) A), forming
a distorted octahedral geometry. The four oxygen atoms
(O2, O3, O8 and O1A) consist the equatorial plane, two
nitrogen atoms are in the axial positions, N3–Co1–N4B
bond angle being 175.7 (1)ꢁ.
3.4. Structural description of [Co{3,5-(NO2)2sal}(phen)]n
(4) and [Zn{3,5-(NO2)2sal}(phen)]n (5)
3,5-(NO2)2sal ligands adopt chelating–bridging mode.
Every 3,5-(NO2)2sal ligand links two neighboring cobalt
atoms into a 1D right-handed helix structure along the b
axis. And then neighboring chains are connected through
4,40-bipyridine ligands, forming a 2D rectangular grid-like
network fragment (see Fig. 6). The CoÆÆÆCo distance
between the adjacent cobalt atoms through the carboxyl
The title complexes 4 and 5 crystallize in the P21/n space
group and adopt helical chain structure consisting of
Co{3,5-(NO2)2sal}(phen) or Zn{3,5-(NO2)2sal}(phen)
entities. The complexes 4 and 5 constitute a pair of isomor-
phous. Xu J.-N. et al. [30] reported that the hydrothermal
synthesis of Co(NH3)6Cl3, 1,10-phenanthroline, 3,5-
dinitrosalicylic acid, and H2O at 140 ꢁC for 72 h yielded
deep red platelet crystals of complex Co{3,5-(NO2)2sal}-
(phen) with space group Cc. The title complex [Co{3,5-
(NO2)2sal}(phen)]n (4) and the complex in [30] are
˚
bridge is 5.183(2) A, while the corresponding CoÆÆÆCo dis-
0
˚
tance through 4,4 -bipyridine is 11.415(4) A. The vertex
angles of lattice are 85.04(1)ꢁ and 94.96(1)ꢁ, respectively.

158
D.-C. Wen et al. / Journal of Molecular Structure 876 (2008) 154–161
Table 3
Hydrogen bond lengths (A) and angles (ꢁ) for the complexes 1–5
˚
D–HÆÆÆA
d(D–H)
d(HÆÆÆA)
d(DÆÆÆA)
<(DHA)
Compound 1
O(8)–H(08A)ÆÆÆO(2)a
O(8)–H(08B)ÆÆÆO(6)b
C(17)–H(17A)ÆÆÆO(5)b
C(10)–H(10A)ÆÆÆO(4)c
C(8)–H(8A)ÆÆÆO(6)d
0.819(2)
0.877(2)
0.931(4)
0.930(4)
0.929(3)
1.937(2)
2.436(3)
2.535(3)
2.619(4)
2.642(3)
2.710(3)
3.264(4)
3.351(5)
3.438(5)
3.308(4)
157.0(2)
157.8(2)
146.6(2)
147.1(2)
129.1(2)
Compound 2
O(9)–H(09A)ÆÆÆO(1)a
O(9)–H(09B)ÆÆÆO(4)b
O(8)–H(08B)ÆÆÆO(1)c
O(8)–H(08A)ÆÆÆO(5)d
C(10)–H(10A)ÆÆÆO(6)e
C(13)–H(13A)ÆÆÆO(7)f
0.87(1)
0.81(1)
0.86(2)
0.79(9)
0.95(1)
0.99(2)
1.91(3)
2.24(4)
1.89(4)
2.08(2)
2.43(2)
2.34(3)
2.77(4)
3.04(5)
2.74(6)
2.85(3)
3.11(3)
3.26(5)
171.9(2)
170.4(2)
173.1(2)
170.1(2)
127.4(3)
154.9(3)
Compound 3
C(14)–H(14A)ÆÆÆO(4)a
C(16)–H(16A)ÆÆÆO(6)b
C(8)–H(8A)ÆÆÆO(5)c
0.930(6)
0.929(8)
0.930(8)
2.40(1)
2.54(1)
2.56(2)
3.27(2)
3.10(2)
3.11(2)
155.3(5)
119.41(4)
117.51(6)
Compound 4
C(10)–H(10A)ÆÆÆO(7)a
C(16)–H(16A)ÆÆÆO(6)b
C(12)–H(12A)ÆÆÆO(5)c
0.930(5)
0.930(4)
0.929(5)
2.465(4)
2.65(1)
2.67(1)
3.038(6)
3.42(1)
3.47(2)
120.0(3)
139.7(3)
144.0(3)
Compound 5
C(10)–H(10A)ÆÆÆO(7)a
C(16)–H(16A)ÆÆÆO(6)b
C(12)–H(12A)ÆÆÆO(5)b
0.932(6)
0.930(5)
0.931(5)
2.482(4)
2.645(5)
2.63(1)
3.046(7)
3.412(7)
3.42(1)
119.1(4)
140.2(3)
142.7(4)
Fig. 1. Coordination arrangements of the Cd(II) atom in 1 with 30%
probability ellipsoid. Hydrogen atoms are omitted for clarity. Symmetry
code (A) x ꢀ 1/2, ꢀy + 1/2, ꢀz + 1.
a
b
Symmetry code: 1
c
ꢀ0.5 + x, 0.5 ꢀ y, 1 ꢀ z; ꢀ0.5 + x, y, 0.5 ꢀ z;
a b
d
1 ꢀ x, ꢀy, 1 ꢀ z; x, 0.5 ꢀ y, 0.5 + z. 2 ꢀx, ꢀy, 1 ꢀ z; ꢀx, 1 ꢀ y,
c
d
e
1 ꢀ z; 1 ꢀ x, ꢀy, 1 ꢀ z; 1 ꢀ x, 1 ꢀ y, 1 ꢀ z; ꢀ1 + x, y, ꢀ1 + z;
f
a
b
ꢀ1 + x, 1 + y, ꢀ1 + z. 3 2 ꢀ x, ꢀy, 2 ꢀ z; 2 ꢀ x, 1 ꢀ y, 2 ꢀ z;
c
a
b
x, 0.5 ꢀ y, ꢀ0.5 + z. 4 0.5 + x, 0.5 ꢀ y, ꢀ0.5 + z; 0.5 ꢀ x, 0.5 + y,
c
a
0.5 ꢀ z; 0.5 + x, 1.5 ꢀ y, ꢀ0.5 + z.
5
ꢀ0.5 + x, 1.5 ꢀ y, 0.5 + z;
b
c
1.5 ꢀ x, ꢀ0.5 + y, 0.5 ꢀ z; ꢀ0.5 + x, 0.5 ꢀ y, 0.5 + z.
Fig. 2. (a) Extended 2D network structure along ac plane in 1. 1,10-Phen
are omitted for clarity. Dashed lines represent the hydrogen bonds. (b)
Right-handed helix (b1) and left-handed helix (b2) in 1. Unnecessary
atoms are omitted for clarity.
Fig. 3. Molecular structure of the complex 2 with 30% probability
ellipsoid.
polymorphic. The CoÆÆÆCo distance between the two neigh-
boring cobalt atoms in the helical chain of complex 4 is
van der Waals radius of cobalt and zinc are different from
that of manganese, the corresponding distances of Co–O
and Co–N, Zn–O and Zn–N are a little different from that
of Mn–O and Mn–N.
As illustrated in Table 3 and the packing diagrams of
complexes 4 and 5 (Supplementary Fig. S4), C–HÆÆÆO
hydrogen bonds between the phenyl hydrogens of phen
˚
5.331 A, while the corresponding CoÆÆÆCo distance of the
˚
complex [30] is 4.085 A.
The title complexes 4,
5
and the complex
[Mn(phen){3,5-(NO2)2sal2ꢀ}]n reported by [31] are isomor-
phous. They all exhibit the one-dimensional left- and right-
handed helical chains (Supplementary Fig. S3). Because the

D.-C. Wen et al. / Journal of Molecular Structure 876 (2008) 154–161
159
Fig. 4. (a) Extended 2D layer observed in 2 down the a axis, the discrete oxygen atoms represent the coordinated water molecules in order to clarity.
Symmetry codes: (A) 1 ꢀ x, ꢀy, 1 ꢀ z; (B) ꢀx, ꢀy, 1 ꢀ z. (b) Side view of the extended 2D layer in 2 down the b axis. (c) The 3D supramolecular structure
in 2. Dashed lines represent the hydrogen bonds.
Fig. 5. Coordination environment of the Co(II) atom in 3 with 30%
Fig. 6. (a) The 2D rectangular grid-like structure in 3. Hydrogen atoms
probability ellipsoid. Hydrogen atoms and solvent water molecules are
and solvent water molecules are omitted for clarity. (b) Right-handed helix
omitted for clarity. Symmetry codes: (A) ꢀx + 1, y ꢀ 1/2, ꢀz + 3/2;
in 3. Unnecessary atoms are omitted for clarity.
(B) x ꢀ 1, y, z.
ligands and the NO2 groups of 3,5-(NO2)2sal ligands are
the major intermolecular force between the neighboring
chains and play an important role in stable the crystal
structures Fig. 7.

160
D.-C. Wen et al. / Journal of Molecular Structure 876 (2008) 154–161
Fig. 7. (a) Coordination arrangements of the M(II) atoms (M = Co and Zn for complexes 4 and 5, respectively) with 30% probability ellipsoid. Hydrogen
atoms are omitted for clarity. (b) The 1D helical chain of complex 4 along b axis. Hydrogen atoms are omitted for clarity.
3.5. Thermogravimetric analysis
4. Conclusions
The thermogravimetric analysis of 1 (see Supplementary
Fig. S5) shows the loss of one coordinated water molecule
between 170 and 202 ꢁC (found, 3.56%; calcd., 3.36%) and
an explosive weight loss at 346 ꢁC. The TG curve shows
that complex 4 is stable up to 250 ꢁC, an explosive weight
loss at 402 ꢁC. Complex 5 is stable up to 300 ꢁC, an explo-
sive weight loss at 422 ꢁC. Metal complexes of 3,5-dinitro-
salicylic acid are potentially explosive.
Three 1D helical coordination polymers (complexes 1,
4 and 5), one mononuclear complex (complex 2) and
one 2D rectangular grid-like coordination polymer (com-
plex 3) with mixed ligands (3,5-(NO2)2sal and N-donor
ligand) have been hydrothermally synthesized and charac-
terized. 3,5-(NO2)2sal ligands in 1, 3, 4 and 5 adopt che-
lating–bridging mode, while 3,5-(NO2)2sal in 2 has a
mono-chelating mode. The C–HÆÆÆO hydrogen bonds,
formed between the NO2 groups of 3,5-(NO2)2sal ligands
and phenyl hydrogens of phen or 4,40-bipy ligands, are
the major binding force to lead to the formation of
three-dimensional supramolecular framework structures.
From the syntheses and structures among complexes 1–5,
we can conclude that the formation of these complexes
is significantly dependent on many factors, such as the
coordination geometry of the metal centers, the coordina-
tion modes of the 3,5-(NO2)2sal ligands, pH value of the
solution, and temperature.
3.6. Photoluminescence
The emission spectra of complexes 1 and 5 and the free
3,5-(NO2)2sal ligand in the solid state at room temperature
are investigated (Supplementary Figs. S6 and S7). Complex
1 exhibits stronger blue fluorescent emission at ca. 485 nm
and weaker emission bands at 527 and 539 nm upon exci-
tation at ca. 355 nm, while complex 5 exhibits stronger blue
fluorescent emission at ca. 483 nm and weaker emission
bands at 535 nm upon excitation at ca. 360 nm. The peaks
at 485 and 483 nm in 1 and 5 would be assigned to the
intraligand fluorescent emission because similar emissions
are observed for the free 3,5-(NO2)2sal ligand. The weaker
emission bands at 527, 539 and 535 nm would be assigned
to the emission of LMCT [34,35].
Acknowledgements
This project was financially supported by the Natural
Science Foundation of China ((Nos. 20431010 and
20171012) and the Natural Science Foundation of Fujian
Province, China (E0110010).
3.7. IR spectra
Appendix A. Supplementary data
Two absorption peaks at 1626 and 1426 cmꢀ1 in the IR
spectra for 2 and 1615 and 1428 cmꢀ1 for 4 are attributed
to the COO antisymmetric and symmetric stretching fre-
quencies, respectively (Supplementary Figs. S8 and S9).
The difference between the asymmetric and symmetric
stretching vibrations (Dv = vas(COOꢀ) ꢀ vs(COOꢀ)) is
200 cmꢀ1 for 2 and 187 cmꢀ1 for 4, suggesting that the
3,5-dinitrosalicylate anions are coordinated to metal atom
as a unidentate group in 2 and a bridging bidentate group
in 4 [36]. The peaks at 3551, 3481 cmꢀ1 in 2 could be attrib-
uted to OH vibration of coordination water.
The crystallographic data of the structures described in
this paper were deposited in the Cambridge Crystallo-
graphic Data Center with the CCDC deposition numbers
631506, 631507, 631508, 631509, 631510, respectively.
The TG curves for complexes 1, 4 and 5, Emission spectra
of compounds 1, 5 and 3,5-(NO2)2sal ligand and the IR
spectra of 2 and 4 were deposited in the online version.
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.molstruc.
2007.06.031.

D.-C. Wen et al. / Journal of Molecular Structure 876 (2008) 154–161
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