A novel strong fluorescent three-dimensional supramolecular coordination polymer based on bridging terephthalate

Article abstract of DOI:10.1016/j.inoche.2003.11.017

A novel coordination polymer [Cd(bpy)(tp)(H₂O)]_n (1) has been prepared through hydrothermal reaction and structurally characterized, and the compound gives strong fluorescent emission. The structure of the compound consists of CdN₂O₄ octahedron linked through bridging terephthalate (tp) into 1D structure, and then a 3D supramolecular structure is formed adopting herringbone packing in the solid state through π-π stacking and hydrogen bonding interactions.

Full text of DOI:10.1016/j.inoche.2003.11.017

Inorganic Chemistry Communications 7 (2004) 260–263
www.elsevier.com/locate/inoche
A novel strong fluorescent three-dimensional
supramolecular coordination polymer based
on bridging terephthalate q
a
a,
a
a
a
Hong-Bin Xu , Zhong-Min Su *, Kui-Zhan Shao , Ya-Hui Zhao , Yan Xing ,
b
Yu-Cang Liang , Heng-Jun Zhang , Dong-Xia Zhu
a
a
a
Faculty of Chemistry, Institute of Functional Material Chemistry, Northeast Normal University, Changchun, Jilin 130024, PR China
b
Anorganisch – Chemisches Institut, Technische Universitaet Muenchen, Lichtenbergstrasse 4, D-85747 Garching, Germany
Received 23 October 2003; accepted 18 November 2003
Published online: 9 December 2003
Abstract
A novel coordination polymer [Cd(bpy)(tp)(H2O)]n (1) has been prepared through hydrothermal reaction and structurally
characterized, and the compound gives strong fluorescent emission. The structure of the compound consists of CdN2O4 octahedron
linked through bridging terephthalate (tp) into 1D structure, and then a 3D supramolecular structure is formed adopting her-
ringbone packing in the solid state through p–p stacking and hydrogen bonding interactions.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Crystal structure; Strong fluorescence; Hydrogen bonds; p–p stacking; Herringbone network
The design and synthesis of coordination polymer
have attracted much attention in recent years owing to
their fascinating molecular structures [1] and potential
application, such as magnetism [2], electrical conduc-
tivity [3], adsorption [4], separation [5], biology [6] and
catalysis [7]. Mostly coordination polymer are con-
structed by using appropriate organic ligand, especially
bridging ligands containing multi-dentate oxygen, ni-
trogen, or sulfur donors, to coordinate to transition
metal centers [8]. The bridging ligand is one of the im-
portant factors that greatly influences the structure of
coordination polymer [9].
Terephthalates (tp) have been used in many synthetic
systems because they can form short bridges via one
carboxylato end or long bridges via the benzene ring,
leading a great variety of structures by formation of
binuclear metal complexes [10], tetranuclear metal
complexes [11], 1D [12], 2D [13] and 3D [2a,14] coor-
dination polymers. In addition, Zn(II), Cd(II) and
Ag(I), d10 metal complexes including tp give strange
photoluminescent phenomena [12c,12d,14b,15]. Here,
we report a new coordination polymer [Cd(bpy)(tp)
(H2O)]n which possesses strong fluorescent property.
The compound 1 was prepared from a mixture of
Cd(CH3COO)2 ꢀ 2H2O (0.133 g, 0.5 mmol), tp (0.084 g,
0.5 mmol), bpy (0.078 g, 0.5 mmol), NaOH (0.04g, 1
mmol) and H2O (16 ml) in a 25-ml Teflon-lined stainless
steel autoclave and heated for 7 days at 180 °C [16].
X-ray crystallography [17] reveals that compound 1
consists of 1D zigzag [Cd(bpy)(tp)(H2O)]n chain. The
molecular structure and atom-labeling scheme of the
title compound 1 is given in Fig. 1. The cadmium atom
has a distorted octahedral coordination environment
with two carboxylato-oxygen atoms O(1) and O(2) from
a tp, a nitrogen atom N(1) from bpy and another oxygen
atom O(5) from a water molecule in equatorial positions
and the nitrogen atom N(2) from the same bpy and one
carboxylato-oxygen atom O(4B) from the other tp in
axial ones. The bpy ligand acts as a typical chelating
q Supplementary data associated with this article can be found, in the
online version, at doi:10.1016/j.inoche.2003.11.017.
* Corresponding author. Tel.: +864315269747; fax: +864315684009.
E-mail address: zmsu@nenu.edu.cn (Z.-M. Su).
1387-7003/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2003.11.017

H.-B. Xu et al. / Inorganic Chemistry Communications 7 (2004) 260–263
261
are parallel and the centroid–centroid distance is 3.4961
ꢀ
A. In addition there are p–p stacking interactions be-
tween the phenyl of the tp and the bpy, and two dis-
tances of the adjacent phenyl and pyridyl are 3.2539
ꢀ
and 4.0417 A, respectively. Therefore, through hydro-
gen bonds and p–p stacking interactions, the undulat-
ing layers further extend to a supramolecular network
(Fig. 2(a)) in which the p–p stacking rectangular units
are arranged perpendicularly each other and distrib-
uted alternately forming a ‘‘herringbone-like’’ structure
[20] (Fig. 2(b)).
Fig. 1. The molecular structure and atom-labeling scheme of 1.
The UV spectrum of 1 in the solid state exhibits two
high-energy absorptions at 253 and 301 nm, which can
be due to an interligand p–pꢁ transition. In the solid
state at ambient temperature, a fluorescent emission of 1
at 379 nm is so strong that the slit of the excited light
ligand terminally coordination to the Cd(II) metal cen-
ter. The terephthalate acting as a good bridge ligand can
have many diverse coordinated mode [2a,18] (Scheme 1).
Here, tp adopts a rare tridentate coordinated mode b in
Scheme 1 to link to two metal centers. The bridging tp
ligand unlike the free molecule is no coplanar and highly
twisty. The torsion angle of the two carboxylato and the
phenyl is 5.63° and 12.58°, respectively. The distance of
ꢀ
the two adjacent Cd(II) is 11.304 A, resulting in
[Cd(bpy)(tp)(H2O)]n zigzag chains. And the Cdꢀ ꢀ ꢀ
Cdꢀ ꢀ ꢀCd angle formed by the three adjacent Cd(II) at-
oms is 104.17°. Both carboxylate ends function in an
asymmetric chelate mode, as evidenced by the Cd(1)–
ꢀ
ꢀ
O(1) [2.3686(13) A] and Cd(1)–O(2) [2.3841(13) A] bond
lengths.
Hydrogen bond interactions are usually important
in the synthesis of supramolecular architecture [19].
There are persistent 1D O–Hꢀ ꢀ ꢀO hydrogen bond
interactions between adjacent [Cd(bpy)(tp)(H2O)]n
chains. The distance of the carboxylate groups and
ꢀ
coordinated H2O is 2.697 A and O–Hꢀ ꢀ ꢀO angle is
177.51°, which indicates a strong O–Hꢀ ꢀ ꢀO hydrogen
bond and plays an important role in the stabilization of
the layer structure and the control of the orientation of
the tp ligands. At the same time aromatic p–p stacking
interactions are also apparent in 1. Here are two kinds
of the p–p stacking interactions and three aromatic
distances in one rectangular unit. The two bpy ligands
O
O
O
O
O
O
O M
O
M
M
M
a
b
d
O-
O
O
O M
O
M O
M O
M O
c
M O
M O
M O
M O
O M
O
O M
O M
Fig. 2. (a) Perspective view of the 3D supramolecular network along
the c-axis. (b) Representation of the supramolecular network along the
c-axis showing the herringbone arrangement of tapes in adjacent
stacks.
e
f
Scheme 1. Typical coordination modes for the tp ligand.

262
H.-B. Xu et al. / Inorganic Chemistry Communications 7 (2004) 260–263
350
300
250
200
150
100
50
References
Em(Ex=320nm, Ex.slit=2.5nm, Em.slit=5nm)
379nm
[1] (a) B. Moulton, M.J. Zaworotko, Chem. Rev. 101 (2001) 1629;
(b) M. Eddaoudi, D.B. Moler, L.-H. Li, B. Chen, T.M. Reineke,
M. OÕKeeffe, O.M. Yaghi, Acc. Chem. Res. 34 (2001) 319.
[2] (a) D.-F. Sun, R. Cao, Y.-C. Liang, Q. Shi, W.-P. Su, M.-C.
Hong, J. Chem. Soc., Dalton Trans. (2001) 2335;
(b) K.S. Min, M.P. Suh, J. Solid State Chem. 152 (2000) 183;
(c) V.V. Pavlishchuk, I.A. Koval, E. Goreshnik, A.W. Addison,
G.A. Albada, J. Reedijk, Eur. J. Inorg. Chem. (2001) 297.
[3] W. Kobel, M. Hanack, Inorg. Chem. 25 (1986) 103.
[4] (a) M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter, M.
OÕKeeffe, O.M. Yaghi, Science 295 (2002) 469;
(b) S.S. Chui, S.M. Lo, J.P.H. Charmant, A.G. Orpen, I.D.
Williams, Science 283 (1999) 1148.
0
[5] (a) K.S. Min, M.P. Sun, Chem. Eur. J. 7 (2001) 303;
(b) S.-I. Noro, S. Kitagawa, M. Kondo, K. Seki, Angew. Chem.,
Int. Ed. 39 (2000) 2082.
300
350
400
450
500
550
600
Wavelength (nm)
[6] B.L. Chen, M. Eddaoudi, S.T. Hyde, M. OÕKeeffe, O.M. Yaghi,
Science 291 (2001) 1021.
Fig. 3. Fluorescence emission spectrum of 1 in the solid state at room
temperature.
[7] J.S. Seo, D. Whang, H. Lee, S.I. Jun, J. Oh, Y.J. Jeon, K. Kim,
Nature 404 (2000) 982.
(kexc ¼ 320 nm) was 2.5 cm while the emission slit is 5
cm Fig. 3, which may be assigned to the symmetry de-
crease of tp (seriously twisted) in 1 [14b] or the chelating
of the tp ligands to cadmium ions that effectively in-
creases the rigidity of the ligand and reduces the loss of
energy via radiationless decay of the interligand emis-
sion excited state [12c].
The TG curve shows there are three-step weight los-
ses from room temperature to 650 °C, which correspond
to the removal of coordinated H2O, tp and bpy ligands,
respectively. It should be noted that no obvious weight
loss was observed in the temperature range 317–347 °C
after the decomposition of the tp ligand. Therefore, the
TGA curve of 1 indicates that the chelating coordina-
tion of Cd and bpy ligand is far more stable than that of
the Cd and tp ligand.
[8] (a) P.J. Hagrman, D. Hagrman, J. Zubieta, Angew. Chem., Int.
Ed. 38 (1999) 2639;
(b) S.R. Batten, R. Robson, Angew. Chem., Int. Ed. 37 (1998)
1460.
[9] L.-J. Zhang, J.-Q. Xu, Z. Shi, W. Xu, T.-G. Wang, J. Chem. Soc.,
Dalton Trans. (2003) 1148.
[10] (a) P. Chaudhuri, K. Oder, K. Wieghardt, S. Gehring, W. Haase,
B. Nuber, J. Weiss, J. Am. Chem. Soc. 110 (1988) 3657;
(b) Z.-L. Deng, J. Shi, Z.-H Jiang, D.-Z. Liao, S.-P. Yan, G.-L.
Wang, H.-G. Wang, R.-J. Wang, Polyhedron 11 (1992) 885;
(c) J. Cano, G.D. Munno, J.L. Sanz, R. Ruiz, J. Faus, F. Lloret, M.
Julve, A. Caneschi, J. Chem. Soc., Dalton Trans. (1997) 1915.
€
[11] K.S. Burger, P. Chaudhuri, K. Wieghardt, B. Nuber, Chem. Eur.
J. 1 (1995) 583.
[12] (a) R.H. Groeneman, L.R. MacGillvrey, J.L. Atwood, Inorg.
Chem. 38 (1999) 208;
(b) L. Deakin, A.M. Arif, J.S. Miller, Inorg. Chem. 38 (1999)
5872;
(c) L.-N. Zhu, L.-Z. Zhang, W.-Z. Wang, D.-Z. Liao, P. Cheng,
Z.-H. Jiang, S.-P Yan, Inorg. Chem. Commun. 5 (2002) 1017,
and references therein;
In conclusion, we report a novel 1D coordination
polymer [Cd(bpy)(tp)(H2O)]n (1) which exhibit a 3D
herringbone-like supramolecular structure. The title
compound gives strong fluorescent emission.
(d) X.-M. Zhang, M.-L. Tong, M.-L. Gong, X.-M. Chen, Eur. J.
Inorg. Chem. (2003) 138.
[13] E. Bakalbassis, P. Bergerat, O. Kahn, S. Jeannin, Y. Jeannin, Y.
Dromzee, M. Guillot, Inorg. Chem. 31 (1992) 625.
[14] (a) C.S. Hong, Y. Do, Inorg. Chem. 36 (1997) 5684;
(b) H.-K. Fun, S.S.S. Raj, R.-G. Xiong, J.-L. Zuo, Z. Yu, X.-Z.
You, J. Chem. Soc., Dalton Trans. (1999) 1915;
(c) H.J. Choi, M.P. Suh, Inorg. Chem. 38 (1999) 6309.
[15] (a) J.-C. Dai, X.-T. Wu, Z.-Y. Fu, S.-M. Hu, W.-X. Du, C.-P.
Cui, L.-M. Wu, H.-H. Zhang, R.-Q. Sun, J. Chem. Soc.,
Chem. Commun. (2002) 12;
Supplementary material
Crystal data and structure refinement, atomic coor-
dinates, bond lengths and angles, IR, UV, TG spectra of
compound 1 were available from the authors on request.
CCDC reference number: 222426.
(b) J. Fan, W.-Y. Sun, T. Okamura, J. Xie, W.-X. Tang, N.
Ueyama, New J. Chem. 26 (2002) 199;
(c) J.-C. Dai, S.-M. Hu, X.-T. Wu, Z.-Y. Fu, W.-X. Du, H.-H.
Zhang, R.-Q. Sun, New J. Chem. 27 (2003) 914.
[16] Elem. Anal. Calc. for compound C18H14N2O5Zn (1) (450.71): C,
47.96; H, 3.14; N, 6.22. Found: C, 47.75; H, 3.22; N, 6.12%. IR
(cmꢂ1): 3427w, 3067m, 1689s, 1574s, 1438m, 1377s, 1290m, 752m,
524m.
Acknowledgements
This work was financially supported by the National
Natural Science Foundation of China (Project Nos.
20160025 and 20243003) and Trans-Century Training
Programme Foundation for the Talents by the State-
Education commission of China.
[17] Crystal data for C18H14CdN2O5 (1): Monoclinic, space group
ꢀ
ꢀ
ꢀ
P21=n, a ¼ 10:017ð2Þ A, b ¼ 16:324ð3Þ A, c ¼ 11:457ð2Þ A,
b ¼ 112:50ð3Þ°, V ¼ 1730:8ð6Þ A , Z ¼ 4, Dcalc ¼ 1:730 g/cm3,
3
ꢀ
l ¼ 1:294 mmꢂ1, F ð000Þ ¼ 896, T ¼ 293ð2Þ K. 17,091 reflections

H.-B. Xu et al. / Inorganic Chemistry Communications 7 (2004) 260–263
263
ꢀ
measured (2:29° < l < 27:48°; k ¼ 0:71073 A), 3970 unique
ðRint ¼ 0:0318Þ. Structure solution and refinement based on 3970
independent reflections with I > 2rðIÞ and 291 parameters gave
R1ðwR2Þ ¼ 0:0209 ð0:0448Þ and S ¼ 0:932.
[19] M.J. Krische, J.-M. Lehn, Struct. Bonding 96 (2000) 3.
[20] (a) G.L. Ning, L.P. Wu, K. Sugimoto, M. Munakata, T. Kuroda-
Sowa, M. Maekawa, J. Chem. Soc., Dalton Trans. (1999)
2529;
[18] C.S. Hong, S.K. Son, Y.S. Lee, M.J. Jun, Y. Do, Inorg. Chem. 38
(1999) 5602.
(b) E. Batchelor, J. Klinowski, W. Jones, J. Mater. Chem. (2000)
839.