Syntheses, structures, and luminescent properties of two cadmium(II) and manganese(II) coordination polymers based on the 11-fluoro-dipyrido[3,2-a: 2′,3′-c]-phenazine ligand

Article abstract of DOI:10.1007/s11243-013-9710-z

Two new coordination polymers, namely [Cd(4-nitro-1,2-BDC))(L)] (1) and [Mn(1,3-BDC)(L)] (2) (4-nitro-1,2-BDC = 4-nitro-1,2-benzenedicarboxylate, 1,3-BDC = 1,3-benzenedicarboxylate, and L = 11-fluoro-dipyrido[3,2-a:2′, 3′-c]phenazine), have been synthesized from phen derivative L and dicarboxylates under hydrothermal conditions. Their crystal structures have been determined by single-crystal X-ray diffraction analyses and further characterized by physicochemical and spectroscopic methods. Both compounds 1 and 2 show 1D chain structures. However, neighboring chains of 2 are further joined together by π···π interactions. Furthermore, the compound 1 shows good fluorescence properties in solid state at room temperature. Graphical Abstract: Two new coordination polymers based on 11-fluoro-dipyrido[3,2-a:2′,3′-c]phenazine and different dicarboxylates have been synthesized under hydrothermal conditions, where the fluorescence properties in solid state at room temperature have been studied. [Figure not available: see fulltext.]

Full text of DOI:10.1007/s11243-013-9710-z

Transition Met Chem (2013) 38:449–453
DOI 10.1007/s11243-013-9710-z
Syntheses, structures, and luminescent properties of two
cadmium(II) and manganese(II) coordination polymers based
on the 11-fluoro-dipyrido[3,2-a:20,30-c]-phenazine ligand
•
Zhi-Guo Kong Xu-Ran Sun Ling Li
•
•
•
Han-Xue Wang Xiu-Yan Wang Seik Weng Ng
•
Received: 25 January 2013 / Accepted: 28 February 2013 / Published online: 15 March 2013
Ó Springer Science+Business Media Dordrecht 2013
Abstract Two new coordination polymers, namely
[Cd(4-nitro-1,2-BDC))(L)] (1) and [Mn(1,3-BDC)(L)]
(2) (4-nitro-1,2-BDC = 4-nitro-1,2-benzenedicarboxylate,
1,3-BDC = 1,3-benzenedicarboxylate, and L = 11-fluoro-
dipyrido[3,2-a:20,30-c]phenazine), have been synthesized
from phen derivative L and dicarboxylates under hydro-
thermal conditions. Their crystal structures have been
determined by single-crystal X-ray diffraction analyses and
further characterized by physicochemical and spectro-
scopic methods. Both compounds 1 and 2 show 1D chain
structures. However, neighboring chains of 2 are further
joined together by pꢀꢀꢀp interactions. Furthermore, the
compound 1 shows good fluorescence properties in solid
state at room temperature.
selection of ligands as basic building blocks is of great
importance during the syntheses of the coordination poly-
mers because slight structural changes in organic building
blocks, such as length, flexibility, and symmetry, can dra-
matically change the structural motifs of coordination
polymers [4–6]. So far, a large number of supramolecular
architectures have been prepared based on metal ions which
can yield various coordination geometries as connecting
centers, plus polyfunctional organic ligands such as pyri-
dine-type N-donors and carboxylate-type O-donors as link-
ers [7–12]. It is well known that 2,20-bipyridyl-like ligands,
for example, 1,10-phenanthroline (phen), are bidentate
chelating ligands, which have been widely used in the con-
struction of the polymeric framework. However, its deriva-
tive 11-fluoro-dipyrido[3,2-a:20,30-c]phenazine (L) (Fig. 1),
as a good candidate for construction of supramolecular
architectures, has received less attention [13].
Introduction
In this work, we report the syntheses, crystal structures,
elemental analyses, thermogravimetric analysis, and lumi-
nescent properties of two novel coordination polymers
based on L and different dicarboxylates, [Cd(4-nitro-1,2-
BDC))(L)] (1) and [Mn(1,3-BDC)(L)] (2) (4-nitro-1,2-
BDC = 4-nitro-1,2-benzenedicarboxylate and 1,3-BDC =
1,3-benzenedicarboxylate). Their structures have been
determined by single-crystal X-ray diffraction analyses, IR
spectra, and elemental analyses. In addition, the TGA and
luminescent properties of the complexes have also been
investigated in the solid state at room temperature.
In the past decades, coordination polymers have been
intensely studied because of their various applications
including gas storage, ion exchange, catalysis, and fluores-
cence technology [1–3]. It is well known that judicious
Z.-G. Kong ꢀ X.-R. Sun ꢀ L. Li ꢀ H.-X. Wang ꢀ
X.-Y. Wang (&)
Key Laboratory of Preparation and Applications of
Environmental Friendly Materials, Ministry of Education,
College of Chemistry, Jilin Normal University,
Siping 136000, People’s Republic of China
e-mail: wangxiuyan2001@yahoo.com.cn
S. W. Ng
Department of Chemistry, University of Malaya,
50603 Kuala Lumpur, Malaysia
Experimental
All the materials were of analytical reagent grade and used as
received without further purification. Elemental analysis was
carried out with a Perkin-Elmer 240C analyzer. Thermal
S. W. Ng
Chemistry Department, King Abdulaziz University,
PO Box 80203, Jeddah, Saudi Arabia
123

450
Transition Met Chem (2013) 38:449–453
thermal parameters for all non-hydrogen atoms using
SHELXS-97 [14] and SHELXL-97 [15], respectively.
Carbon-bound H-atoms were placed in calculated positions
˚
(C–H 0.93 A) and were included in the refinement in the
riding model approximation, with U(H) set to 1.2U(C). The
F atoms are disordered over two positions in 0.63(1):0.37
ratio for 1 and 0.70(1):0.30 ratio for 2. The nitro group in 1
is disordered over two positions in a 1:1 ratio in respect of
the O atoms. The details of the crystal structures and
refinements are summarized in Table 1. Selected bond
lengths and angles of 1 and 2 are given in Table 2.
Fig. 1 The ligands used in this work
stability experiments were performed on a TG SDT2960
thermal analyzer from room temperature to 800 °C under a
nitrogen atmosphere at a heating rate of 10 °C min-1. The
photoluminescent properties were measured on a FLSP920
Edinburgh Fluorescence Spectrometer.
Results and discussion
Crystal structure of compound 1
As shown in Fig. 2, the asymmetric unit of 1 contains one
Cd(II) atom, one L ligand, and one 4-nitro-1,2-BDC anion.
The central Cd(II) atom is six-coordinated by four car-
boxylate atoms from three different 4-nitro-1,4-BDC
anions and two nitrogen atoms from one L ligand in an
octahedral sphere. The Cd–O distances vary from 2.247(2)
Preparation of [Cd(4-nitro-1,2-BDC)(L)] (1)
A mixture of CdCl2ꢀ2H2O (1 mmol, 0.192 g), L (1 mmol,
0.300 g), and 4-nitro-1,4-H2BDC (1 mmol, 0.211 g) was
dissolved in 12 ml distilled water, followed by addition of
triethylamine until the pH value of the system was adjusted
to between 5 and 6. The resulting solution was sealed in a
23 ml Teflon-lined stainless-steel autoclave and heated at
426 K for 6 d under autogeneous pressure. After the mix-
ture had been cooled to room temperature at a rate of
10 °C h-1, crystals of 1 were obtained. Yield 0.168 g
(27 %). Anal. for C26H12CdFN5O6 (%): calcd. C 50.2, H
2.0, N 11.3; found C 50.4, H 1.3, N 11.3.
˚
to 2.247(2) A, and the Cd–N distances are 2.405(3) and
˚
2.384(3) A, respectively (Table 2), which are very close to
those found in
a
similar coordination polymer
[Cd2(IP)2(TBZ)2(H2O)2]ꢀ(H2O) (IP = isophthalate and
TBZ = thiabendazole) [16]. Notably, each 4-nitro-1,2-
BDC anion bridges three Cd(II) atoms. In this way, the
4-nitro-1,2-BDC anions bridge neighboring Cd(II) atoms to
Preparation of [Mn(1,3-BDC)(L)] (2)
Table 1 Crystal data and structure refinements for compounds 1 and
2
The preparation of 2 was similar to that of 1 except that
MnCl2ꢀ4H2O (0.1 mmol, 0.020 g) and 1,3-H2BDC
(0.1 mmol, 0.017 g) were used instead of CdCl2ꢀ2H2O
(1 mmol, 0.192 g) and 4-nitro-1,4-H2BDC (1 mmol,
0.211 g) of 1. Crystals of 2 suitable for single-crystal X-ray
diffraction analysis were collected by filtration, washed
several times with distilled water, and dried in air at
ambient temperature. Yield 0.009 g (18 %). Anal. for
C26H13FMnN4O4 (%): calcd. C 60.1, H 2.5, N 10.8; found
C 60.2, H 2.4, N 10.9.
1
2
Empirical formula
Fw
C26H12CdFN5O6
621.81
C26H13FMnN4O4
519.34
Crystal system
Space group
Triclinic
P -1
Monoclinic
C 2/c
˚
a [A]
7.3062(5)
12.9494(8)
14.0305(9)
62.905(1)
75.104(1)
84.085(1)
1141.89(13)
2
15.6305(16)
15.3462(15)
18.3424(19)
90
˚
b [A]
˚
c [A]
a [°]
b [°]
c [°]
109.256(2)
90
X-ray crystallography
3
˚
Volume [A ]
4153.6(7)
8
Z
Single crystal of compounds 1 and 2 was mounted on a
Bruker Smart CCD using Mo Ka radiation (k =
Dc (g/cm3)
1.808
1.661
GOF
1.021
0.973
˚
0.71073 A) and a graphite monochromator at room tem-
Reflns collected/unique
Rint
6229/4418
0.0121
13092/4084
0.0475
perature. All structures were solved by the direct method
and successive Fourier difference syntheses and refined by
the full-matrix least-squares method on F2 with anisotropic
R1 [I [ 2r(I)]
0.0315
0.0553
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Transition Met Chem (2013) 38:449–453
451
˚
Table 2 Selected bond lengths [A] and angles [°] for 1 and 2
Compound 1
Cd(1)–N(2)
2.405(3)
2.323(2)
2.420(3)
90.04(8)
Cd(1)–N(5)
Cd(1)–O(2)i
Cd(1)–O(4)ii
O(2)i–Cd(1)–O(4)ii
2.384(3)
2.247(2)
2.333(3)
80.97(9)
Cd(1)–O(1)
Cd(1)–O(3)
O(2)i–Cd(1)–O(1)
O(1)–Cd(1)–O(4)ii 125.26(9)
O(2)i–Cd(1)–N(5) 116.19(10)
O(1)–Cd(1)–N(5)
O(2)i–Cd(1)–N(2)
O(4)ii–Cd(1)–N(2) 143.91(10) N(5)–Cd(1)–N(2)
O(2)i–Cd(1)–O(3) 165.11(10) O(1)–Cd(1)–O(3)
O(4)ii–Cd(1)–O(3)
N(2)–Cd(1)–O(3)
Compound 2
146.16(9)
O(4)ii–Cd(1)–N(5)
82.02(10)
89.86(9)
69.34(10)
77.54(8)
78.45(10)
92.12(10) O(1)–Cd(1)–N(2)
99.39(9)
95.98(9)
N(5)–Cd(1)–O(3)
Mn(1)–O(1)
Mn(1)–O(3)i
2.269(3)
2.088(3)
2.304(3)
Mn(1)–O(2)
Mn(1)–O(4)ii
Mn(1)–N(4)
2.221(3)
2.120(3)
2.339(3)
91.00(11)
Mn(1)–N(1)
O(3)i–Mn(1)–(4)ii
O(4)ii–Mn(1)–O(2)
101.51(11) O(3)i–Mn(1)–O(2)
99.62(13) O(3)i–Mn(1)–O(1) 141.72(11)
Fig. 2 View of the coordination environment of Cd(II) atom of the
complex 1. All the hydrogen atoms are omitted for clarity
O(4)ii–Mn(1)–O(1) 104.32(11) O(2)–Mn(1)–O(1)
O(3)i–Mn(1)–N(1) 120.20(11) O(4)ii–Mn(1)–N(1)
O(2)–Mn(1)–N(1) 145.18(11) O(1)–Mn(1)–N(1)
57.26(10)
89.49(11)
87.94(10)
O(3)i–Mn(1)–N(4)
O(2)–Mn(1)–N(4) 103.41(13) O(1)–Mn(1)–N(4)
N(1)–Mn(1)–N(4) 70.34(11)
80.25(11) O(4)ii–Mn(1)–N(4) 156.88(11)
86.65(11)
Symmetry transformations used to generate equivalent atoms: for 1
(i) 1 - x, 1 - y, 2 - z; (ii) 2 - x, 1 - y, 2 - z; for 2 (i) 1 - x, 1 -
y, 1 - z; (ii) x, 1 - y, 1 - z
form a 1D chain structure (Fig. 3). The L ligands are
alternately attached on both sides of the chains (Fig. 3).
Crystal structure of compound 2
As illustrated in Fig. 4, the asymmetric unit of 1 contains
one Mn(II) atom, one L ligand, and one 1,3-BDC anion.
Each Mn(II) atom is five-coordinated by four carboxylate
oxygen atoms from two different 1,3-BDC ligands, and two
nitrogen atoms from one L ligand in a distorted octahedral
coordination sphere. Three carboxylate oxygen atoms (O1,
O2, and O3i) and one nitrogen atom (N1) constitute the
plane of the octahedra, and the additional carboxylate
oxygen atom (O4ii) and the nitrogen atom (N4) are at the
axis of the octahedra. The Mn–O bond lengths vary from
Fig. 3 View of the 1D chain structure of 1
interactions to result in a fascinating 2D supramolecular
layer (Fig. 6).
Thermogravimetric analysis (TGA) was performed to
examine the thermal stability of compounds 1 and 2
(Fig. 7). The crushed single-crystal samples were heated up
to 800 °C under N2 gas at a heating rate of 10 °C min-1
The compound 1 is thermally stable up to around 288 °C.
The first weight loss corresponds to the release of 4-nitro-
1,2-BDC anion in the temperature range of 288–400 °C
(obsd 31.5 %, calcd 33.6 %). The second weight loss from
405 to 642 °C corresponds to the decomposition of L
ligand (obsd 47.6 %, calcd 48.3 %). The remaining weight
may be attributed to the formation of CdO (obsd 21.1 %,
calcd 20.6 %). The compound 2 begins to decompose at
.
˚
2.088(3) to 2.269(3) A, and the Mn–N distances are
˚
2.304(3) and 2.339(3) A. Each 1,3-BDC ligand bridges
three Mn(II) atoms. In this way, the 1,3-BDC ligands
bridge neighboring Mn(II) atoms to form a 1D chain
structure (Fig. 5). The L ligands are attached on both sides
of the chain in pairs (Fig. 6). In addition, the L ligands
from neighboring chains are paired through strong p–p
123

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Transition Met Chem (2013) 38:449–453
Fig. 4 View of the
coordination environment of
Mn(II) atom of the complex 2.
All the hydrogen atoms are
omitted for clarity
Fig. 5 View of the 1D chain
structure of 2
175 and ends above 628 °C. The weight loss is attributed to
both the 1,3-BDC anion and L ligand (obsd 86.0 %, calcd
89.4 %). However, it is difficult to determine these weight
losses accurately as these processes are overlapped with the
weight losses due to the dissociation of the 1,3-BDC anion
and L ligand. The remaining weight may be attributed to
the formation of MnO (obsd 14.0 %, calcd 13.7 %).
It is well known that coordination polymers with d10
metals show interesting luminescent properties. Therefore,
the luminescent properties of the free organic ligands and
compound 1 have been investigated in the solid state at
room temperature (Fig. 8). The free L and 4-nitro-1,2-
H2BDC show emission bands centered at 495 and 545 nm,
respectively, which can be attributed to the p*–n or p*–p
transitions as previously reported [4]. Compound 1 shows
an emission band at 555 nm (kex = 325 nm). This emis-
sion is similar to that of the 4-nitro-1,2-H2BDC
(kem = 545 nm). Therefore, the emission of 1 should
originate from the 4-nitro-1,2-H2BDC ligand.
Fig. 6 View of the 2D supramolecular layer constructed by p–p
interactions in 2
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Transition Met Chem (2013) 38:449–453
453
Conclusion
Two new Cd(II) and Mn(II) coordination polymers con-
structed from N-donor ligand L and different aromatic
polycarboxylate anions have been prepared under hydro-
thermal conditions. Both compounds 1 and 2 show 1D
chain structures. However, neighboring chains of 2 are
further joined together by pꢀꢀꢀp interactions. Furthermore,
the compound 1 shows good fluorescence properties in the
solid state at room temperature. It is anticipated that more
metal compounds containing the phen derivatives and
aromatic polycarboxylates will be synthesized.
Supplementary materials
CCDC 911677 and 911678 for compounds 1 and 2 contain
the supplementary crystallographic data. The data can be
obtained free of charge from the Cambridge Crystallo-
graphic Data Centre via deposit@ccdc.cam.ac.uk.
Acknowledgments This work was supported by Jilin Province
Science and Technology Development projects (No. 201105085) and
the Ministry of Higher Education of Malaysia (Grant No. UM.C/HIR/
MOHE/SC/12).
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123