Urothermal synthesis of two photoluminescent cadmium coordination polymers

Article abstract of DOI:10.1016/j.inoche.2013.01.030

Two new Cd coordination polymers, [Cd(5-Nisp)(e-urea)]_n (1), and [Cd₂(5-Hisp)₂(e-urea)₂(en)]_n (2), (where 5-Nisp = 5-nitroisophthalate; 5-Hisp = 5-hydroxyisophthalate; e-urea = ethyleneurea; en = 1,2-

Full text of DOI:10.1016/j.inoche.2013.01.030

Inorganic Chemistry Communications 30 (2013) 152–155
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Urothermal synthesis of two photoluminescent cadmium coordination polymers
a
a
E Yang a,b, , Hong-Yan Li , Zi-Sheng Liu , Qi-Dan Ling
⁎
a,⁎⁎
a
Fujian Key Laboratory of Polymer Materials and College of Materials Science and Engineering, Fujian Normal University, Fuzhou, 350007, PR China
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002, PR China
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Two new Cd coordination polymers, [Cd(5-Nisp)(e-urea)]n (1), and [Cd2(5-Hisp)2(e-urea)2(en)]n (2), (where
5-Nisp=5-nitroisophthalate; 5-Hisp=5-hydroxyisophthalate; e-urea=ethyleneurea; en=1,2-ethanediamine),
have been urothermally synthesized by using ethyleneurea hemihydrate as the solvent. Single-crystal X-ray
diffraction analyses reveal that both 1 and 2 have linear chain sub-structures linked by 5-Nisp ligands or 5-Hisp
ligands into three-dimensional frameworks. The thermogravimetric behavior and the photoluminescent proper-
ties of 1 and 2 were studied.
Received 20 December 2012
Accepted 29 January 2013
Available online 4 February 2013
Keywords:
Cadmium
Urothermal synthesis
Ethyleneurea
© 2013 Elsevier B.V. All rights reserved.
Crystal structure
Photoluminescence
Linear chain
Coordination polymers have attracted considerable attention in re-
cent years due to their interesting properties and promising applications
in the areas of heterogeneous catalysis, magnetism, nonlinear optics, gas
storage, and separation etc. [1]. The solvents play an important role in the
self-assembly process of the metal organic frameworks (MOFs), and the
well-known synthetic methods including hydrothermal, solvothermal
and ionothermal synthesis [2–4] have been established and widely
used. At the current stage, the urothermal synthesis of MOFs remains
in the initial stage [5].
To construct novel architectures, different functional groups such as
sulfonate, nitro and hydroxy groups have been attached to benzene-
polycarboxylate [6–8]. Recently, supramolecular Cd frameworks based
on 5-nitroisophthalic acid (5-Nisp) and 5-hydroxyisophthalic acid
(5-Hisp) ligands have been systematically studied [7,8]. The carboxyl
groups of 5-Nisp or 5-Hisp may be completely deprotonated and bond
to metal centers, which may form secondary building units to construct
frameworks with novel structural features. On the other hand,
one-dimensional chain is the basic building block [9,10] in the
structures of coordination polymers. The chain can be zig-zag, lin-
ear, ladder, or helix. Herein, we report the urothermal synthesis,
structures and photoluminescent properties of two interesting
compounds [Cd(5-Nisp)(e-urea)]n (1; e-urea=ethyleneurea) and
[Cd2(5-Hisp)2(e-urea)2(en)]n (2; en=1,2-ethanediamine), which
have linear chain sub-structures linked by 5-Nisp ligands or
5-Hisp ligands into three-dimensional frameworks.
Compounds 1 and 2 were urothermally synthesized through the
assembly of Cd(NO3)·6H2O in ethyleneurea hemihydrate at 120 °C
for 3 days, with 5-Nisp or 5-Hisp, respectively [11]. A single crystal
X-ray analysis reveals that [Cd(5-Nisp)(e-urea)]n (1) crystallizes in
an orthorhombic form with chiral space group P212121 [12]. The
flack parameter of −0.02(3) demonstrates the homochirality of a
single crystal. Spontaneous resolution occurs here and the bulk sam-
ple is racemic because of the achiral precursors. As shown in Fig. 1a,
the Cd1 is octahedrally coordinated with six oxygen atoms, among
which, four oxygen atoms (O1, O2, O3, O4) are from four carboxyl
groups of four different 5-Nisp ligands, and two μ2-O (O7, O7a) are
from two e-urea molecules. The 5-Nisp ligand acts as a μ4-linker,
using its four oxygen atoms to bond to four Cd atoms. The e-urea
acts as the μ2-bridge to link two adjacent Cd atoms. So the e-urea
molecules link the Cd atoms to form a 1D chain, the adjacent Cd
atoms are further linked by the carboxyl groups of 5-Nisp ligands
(Fig. 1b). Then these chains are connected by the aromatic rings of
the 5-Nisp ligands to form the 3D framework (Fig. 1c), which in-
cludes a 1D channel along the a-axis filled by the coordinate
e-urea molecules.
A single crystal X-ray analysis reveals that 2 crystallizes in a
monoclinic P2(1)/n space group. [12] As shown in Fig. 2a, the asym-
metric unit of 2 consists of two crystallographically independent Cd
centers, two 5-Hisp ligands, two e-urea molecules and one en having
half occupation factor. Cd1 is six-coordinated by four oxygen atoms
(O1, O3, O7, O9) from different carboxyl groups of two 5-Hisp ligands,
⁎
Correspondence to: E. Yang, Fujian Key Laboratory of Polymer Materials and College of
Materials Science and Engineering, Fujian Normal University, Fuzhou, 350007, PR China.
Tel.: +86 591 83715075; fax: +86 591 22868666.
⁎⁎ Corresponding author. Tel.: +86 591 83715075; fax: +86 591 22868666.
E-mail addresses: yangeli66@yahoo.com.cn (E. Yang), lingqd@fjnu.edu.cn
(Q.-D. Ling).
1387-7003/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.inoche.2013.01.030

E. Yang et al. / Inorganic Chemistry Communications 30 (2013) 152–155
153
Fig. 1. (a) The coordination environment in 1, H atoms were omitted for clarity; (b) the chain in 1; (c) The three-dimensional structure of 1 viewed along the a-axis, the aubergine
balls indicate the e-urea ligands.
and two oxygen atoms (O11, O12) from two coordinated e-urea mol-
ecules. Differently, Cd2 is eight-coordinated by four oxygen atoms
(O1, O2, O8, O9) from two chelating carboxyl group of 5-Hisp ligands,
two single coordinated oxygen atoms (O4, O6) from two carboxyl
groups of 5-Hisp ligands, and two oxygen atoms (O11, O12) from
two coordinated e-urea molecules. Two 5-Hisp ligands have the
same coordination modes. Each of them acts as a μ4-linker, using its
four oxygen atoms to bond to four Cd atoms. Two e-urea molecules
act as μ2-linker to link adjacent Cd atoms to form a Cd2(e-urea)2
subunit (SBU). Then the Cd2(e-urea)2 SBUs are linked by the carboxyl
groups of 5-Hisp ligands to form a chain (Fig. 2b). Then these chains
are connected by the aromatic rings of the 5-Hisp ligand to form the
3D framework through μ2-ligands (Fig. 2c). The 3D structure exhibits
1D channels along the a-axis, which are blocked with coordination
solvent and en molecules generated from the decomposition of
e-urea (Fig. s3) [13].
Some Cd-(5-Nisp) and Cd-(5-Hisp) framework structures syn-
thesized from hydrothermal or solvothermal methods have been
previously reported [7a,14]. The structures of 1 and 2 presented
are totally different from those reported Cd-(5-Nisp) and Cd-
(5-Hisp) compounds, because the additional e-urea ligands com-
ing from the solvent have been part of the framework structure.
Thus, the e-urea used for synthesis is not only an effective solvent,
but also a structure-directing agent which helps to build the
framework structure. In this work, we found that 1D chain is the
basic building block for 1 and 2. However, the chains in two com-
pounds are totally different. In 1, the e-urea molecules link Cd
atoms to form a 1D chain. In 2, two e-urea molecules link two ad-
jacent Cd atoms to form a Cd2(e-urea)2 SBU, which are further
linked by the carboxyl groups of 5-Nisp ligands to form the 1D
chain.
Thermal gravimetric analysis (TGA) of 1 indicates that the com-
pound 1 has thermal stability up to 350 °C. The compound of 2 has
thermal stability up to 330 °C (Fig. s1). After that temperature, the
frameworks decompose.
Powder X-ray diffraction (PXRD) were measured to confirm the
phase purity and to examine the crystallinity of bulk sample (Fig. s2).
The simulative (black line) and experimental (red line) X-ray pow-
der diffraction pattern for compound 1 and compound 2 are com-
pared, respectively. The diffraction (XRD) peaks are corresponded
well in position, indicating the phase purity of the experimental
compounds.
The fluorescent emission spectra of compounds 1 and 2 were mea-
sured in the solid state at room temperature. Compound 1 (Fig. 3a)
has one intense emission at 440 nm upon photoexcitation at the
λex=350 nm. Compound 2 has one intense emission at 473 nm
upon photoexcitation at λex=350 nm (Fig. 3b). These results indi-
cate that the emission bonds correspond to the intraligand charge
transfers (n→π* or π→π*) [7a,14]. Such luminescent properties of
1 and 2 are similar to those observed in other Cd-(5-Nisp) and
Cd-(5-Hisp) frameworks [13].
In summary, we report here two new compounds 1 and 2 synthe-
sized by using the e-urea as the solvent. The 1D chain is the basic
building block in two compounds. The different numbers of e-urea

154
E. Yang et al. / Inorganic Chemistry Communications 30 (2013) 152–155
Fig. 2. (a) The coordination environment in 2, H atoms were omitted for clarity; (b) the chain in 2; (c) the three-dimensional structure of 2 viewed along the a-axis, the aubergine
ball indicate the e-urea ligands.
molecules in two compounds result in different chains, which further
affect the final framework and symmetry. The results demonstrated
that the e-urea is an effective solvent and structure-directing agent
for the construction of MOFs.
20093223110002), Cultivating Fund for Excellent Young Scholar of
Fujian Normal University (FJSDJK2012063) and Program for Innova-
tive Research Team in Science and Technology in Fujian Province
University (IRTSTFJ).
Acknowledgments
Appendix A. Supplementary material
The authors are grateful for the financial support from the Nation-
al Natural Science Foundation of China (60976019), Specialized Re-
search Fund for the Doctoral Program of Higher Education (SRFDP
Supplementary data to this article can be found online at http://
dx.doi.org/10.1016/j.inoche.2013.01.030.
Fig. 3. Solid-state emission spectra of 1 (a) and 2 (b) at room temperature.

E. Yang et al. / Inorganic Chemistry Communications 30 (2013) 152–155
155
[9] (a) J.-W. Ye, J. Wang, J.-Y. Zhang, P. Zhang, Y. Wang, Construction of 2-D lanthanide
coordination frameworks: syntheses, structures and luminescent property,
CrystEngComm 9 (2007) 515–523;
References
[1] (a) G. Ferey, Hybird porous solids: past, present, future, Chem. Soc. Rev. 37 (2008)
191–214;
(b) Y.X. Ren, S.P. Chen, S.G. Gao, Q.Z. Shi, Syntheses, characterization and the
liquid-phase formation enthalpy changes of two new one-dimensional
ribbon-like lanthanide supermolecular polymers, Inorg. Chem. Commun. 9
(2006) 649–653;
(c) N.L. Rosi, J. Kim, M. Eddaoudi, B. Chen, M. O'Keeffe, O.M. Yaghi, Rod packings
and metal–organic frameworks constructed from rod-shaped secondary
building units, J. Am. Chem. Soc. 127 (2005) 1504–1518;
(d) W.-J. Ji, Q.-G. Zhai, M.-C. Hu, S.-N. Li, Y.-C. Jiang, Y. Wang, Ionothermal synthesis
and characterization of a 3-D (4, 8)-connected porous anionic mental–organic
framework entrapped with 1-D [K2(H2O)6] chains, Inorg. Chem. Commun. 11
(2008) 1455–1458.
(b) J.L.C. Rowsell, O.M. Yaghi, Effects of functionalization, catenation, and variation
of the metal oxide and organic linking units on the low-pressure hydrogen ad-
sorption properties of metal–organic frameworks, J. Am. Chem. Soc. 128 (2006)
1304–1315;
(c) C.N.R. Rao, S. Natarajan, R. Vaidhyanathan, Metal carboxylates with open ar-
chitectures, Angew. Chem. Int. Ed. 43 (2004) 1466–1496;
(d) F. Wang, Z.-S. Liu, H. Yang, Y.-X. Tan, J. Zhang, Hybrid zeolitic imidazolate frame-
works with catalytically active TO4 building blocks, Angew. Chem. Int. Ed. 50
(2011) 450–453;
(e) S.M. Humphrey, P.T. Wood, Mutipie areas of magnetic bistability in the topolog-
ical ferrimagnet [Co3(NC5H3(CO2)2-2,5)2(μ3-OH)2(OH2)2], J. Am. Chem. Soc. 126
(2004) 13236–13237.
[10] (a) Y.B. Go, X.Q. Wang, E.V. Anokhina, A.J. Jacobson, A chain of changes: influence
of noncovalent interactions on the one-dimensional structures of nickel(II)
dicarboxylate coordination polymers with chelating aromatic amine ligands,
Inorg. Chem. 43 (2004) 5360–5367;
[2] (a) Y.-B. Chen, Y. Kang, J. Zhang, New mimic of zeolite: heterometallic organic host
framework accommodating inorganic cations, Chem. Commun. 46 (2010)
3182–3184;
(b) H.-J. Chen, J. Zhang, W.-L. Feng, M. Fu, Synthesis, structures of cobalt/copper
complexes and magnetic property of copper complex with the mixed ligands
5-nitro-1,3-benzenedicarboxylic acid and imidazole, Inorg. Chem. Commun.
9 (2006) 300–303;
(c) Z.-S. Liu, E. Yang, Y. Kang, J. Zhang, Urothermal synthesis of a photoluminescent
zinc coordination polymer, Inorg. Chem. Commun. 14 (2011) 355–357;
(d) P.-X. Yin, J. Zhang, Z.-J. Li, Y.-Y. Qin, J.-K. Cheng, L. Zhang, Q.-P. Lin, Y.-G. Yao, Su-
pra molecular isomerism and various chain/layer substructures in silver(I)
compounds: syntheses, structures, and luminescent properties, Cryst. Growth
Des. 9 (2009) 4884–4896.
(b) Q.-Y. Liu, D.-Q. Yuan, L. Xu, Diversity of coordination architecture of
copper(II)-5-sulfoisophthalic acid: synthesis, crystal structures, and char-
acterization, Cryst. Growth Des. 7 (2007) 1832–1843;
(c) J. Zhang, Y. Kang, R.-B. Zhang, Z.-J. Li, J.-K. Cheng, Y.-G. Yao, A twisting chiral
‘dense’ 75.9 net, incorporating
(2005) 177–178.
a helical sub-structure, CrystEngComm 7
[3] (a) S.T. Zheng, Y. Li, T. Wu, R. Nieto, P.Y. Feng, X.H. Bu, Porous lithium imidazolate
frameworks constructed with charge-complementary ligands, Chem. Eur. J. 16
(2010) 13035–13040;
(b) S.M. Chen, J. Zhang, T. Wu, P.Y. Feng, X.H. Bu, Multiroute synthesis of porous an-
ionic frameworks and size-tunable extraframework organic cation-controlled
gas sorption properties, J. Am. Chem. Soc. 131 (2009) 16027–16029.
[4] (a) J.H. Liao, P.C. Wu, W.C. Huang, Ionic liquid as solvent for the synthesis and crys-
[11] Synthesis of [Cd(5-Nisp)(e-urea)]n (1). A mixture of Cd(NO3)·6H2O (0.163 g,
0.528 mmol), 5-Nisp (0.109 g, 0.517 mmol), e-urea·0.5H2O (1.72 g, 20 mmol)
were sealed in a 25 ml teflon-lined stainless steel autoclave, heated at 120 °C
for 3 days under autogenous pressure. After the reaction was cooled to room
temperature, colorless crystals were produced (yield: 75%, based on Cd). Anal.
Calc. for 1, C11H9CdO7N3: C, 32.41%; H, 2.21%; N, 10.30%. Found: C, 32.47%; H,
2.20%; N, 10.41%. Synthesis of [Cd2(5-Hisp)2(e-urea)2(en)]n (2). A mixture of
Cd(NO3)·6H2O (0.192 g, 0.622 mmol), 5-Hisp (0.103 g, 0.566 mmol),
e-urea·0.5H2O (1.69 g, 19.6 mmol) were sealed in a 25 ml teflon-lined stainless
steel autoclave, heated at 120 °C for 3 days under autogenous pressure. After
the reaction was cooled to room temperature, colorless crystals were produced
(yield: 72%, based on Cd). Anal. Calc. for 2, C23H24Cd2O12N5: C, 35.08%; H,
3.07%; N, 8.89%. Found: C, 35.05%; H, 2.99%; N, 8.81%.
tallization of
a coordination polymer: (EMI)[Cd(BTC)] (EMI=1-ethyl-3-
methylimidazolium, BTC=1,3,5-benzenetricarboxylate), Cryst. Growth Des. 6
(2006) 1062–1063;
(b) Z.J. Lin, D.S. Wragg, J.E. Warren, R.E. Morris, Anion control in the ionothermal syn-
thesis of coordination polymers, J. Am. Chem. Soc. 129 (2007) 10334–10335;
(c) R.E. Morris, Ionothermal synthesis — ionic liquids as functional solvents in the
preparation of crystalline materials, Chem. Commun. 21 (2009) 2990–2998;
(d) J. Zhang, S.M. Chen, X.H. Bu, Multiple functions of ionic liquids in the synthe-
sis of three-dimensional low-connectivity homochiral and achiral frame-
works, Angew. Chem. Int. Ed. 47 (2008) 5434–5437;
(e) W.-J. Ji, Q.-G. Zhai, S.-N. Li, Y.-C. Jiang, M.-C. Hu, The first ionothermal synthe-
sis of a 3D ferroelectric metal–organic framework with colossal dielectric
constant, Chem. Commun. 47 (2011) 3834–3836.
[12] X-ray crystallographic study: Diffraction intensities of 1 and 2 were collected at
293 K direction methods and difference Fouriersynthese (Mo-Ka, λ=0.71073
Ǻ). The crystallographic calculations were conducted using SHELXL-97 pro-
grams. Crystal date for 1:
C11H9CdO7N3, M=407.61, orthorhombic,
a=6.7547(8) Ǻ, b=11.0302(9) Å, c=17.1073(19) Ǻ, β=90o, V=1274.6(2)
Ǻ3, T=293(2) K, space group P212121, Z=4, 10975 reflections measured,
2905 independent reflections (Rint =0.0295). The final R1 values were 0.0180
(I>2σ(I)). The final wR(F2) values were 0.0636 (I>2σ(I)). The final R1 values
were 0.0197 (all data). The final wR(F2) values were 0.0639 (all data). The
goodness of fit on F2 was 0.784. Crystal date for 2: C23H24Cd2O12N5,
M=787.27, monoclinic, a=7.152(2) Ǻ, b=18.283(5) Å, c=19.947(6) Ǻ,
β=90.395(7)o, V=2608.3(13) Ǻ3, T=293(2) K, space group P2(1)/n, Z=4,
6447 reflections measured, 3938 independent reflections (Rint =0.0214). The
final R1 values were 0.0406 (I>2σ(I)). The final wR(F2) values were 0.1021
(I>2σ(I)). The final R1 values were 0.0501(all data). The final wR(F2) values
were 0.1074 (all data). The goodness of fit on F2 was 1.030.
[5] (a) J. Zhang, S. Chen, T. Wu, S.T. Zheng, Y. Chen, R.A. Nieto, P. Feng, X. Bu,
Urothermal synthesis of crystalline porous materials, Angew. Chem. Int. Ed.
49 (2010) 8876;
(b) Z.S. Liu, E. Yang, Y. Kang, J. Zhang, Urothermal synthesis of a photoluminescent
zinc coordination polymer, Inorg. Chem. Commun. 14 (2011) 355–357.
[6] (a) J.W. Ye, J.Y. Zhang, G.L. Ning, G. Tian, Y. Chen, Y. Wang, Lanthanide coordina-
tion polymers constructed from dinuclear building blocks: novel structure
evolution from one-dimensional chains to three-dimensional architectures,
Cryst. Growth Des. 8 (2008) 3098–3106;
(b) D.F. Sun, R. Cao, Y.Q. Sun, W.H. Bi, D.Q. Yuan, Q. Shi, X. Li, Syntheses and
structures of two novel copper complexes constructed from unusual planar
tetracopper(II) SBUs, CrystEngComm 13 (2003) 1528–1529.
[13] H. Yang, T. Li, Y. Kang, F. Wang, Urothermal in situ ligand synthesis to fabricate a
metal–organic framework with (3,4)-connected tfi topology, Inorg. Chem.
Commun. 14 (2011) 1695–1697.
[14] (a) X.J. Li, R. Cao, W.H. Bi, Y.Q. Wang, Y.L. Wang, X. Li, Z.G. Guo, A new family of
cadmium(II) coordination polymers from coligands: effect of the coexistent
groups (R=H, \NO2, \OH) on crystal structures and properties, Cryst.
Growth Des. 5 (2005) 1651–1656;
[7] (a) H.-T. Zhang, Y.-Z. Li, H.-Q. Wang, Emmanuel N. Nfor, X.-Z. You, From loop-like
chain to helix: a result of symmetry breaking triggered by the replacement of
coordination water, CrystEngComm 7 (2005) 578–585;
(b) J.W. Ye, Q. Zhang, K.Q. Ye, W.R. Yin, L. Ye, G.D. Yang, Y. Wang, Synthesis, struc-
ture and photoluminescence of a 2-D cadmium(II) metal–organic framework:
[Cd(μ4-NIPH)(μ2-OH2)]n (NIPH=5-nitroisophthalate), Inorg. Chem. Commun.
9 (2006) 744–747.
(b) J.H. Luo, M.C. Hong, R.H. Wang, R. Cao, L. Han, Z.Z. Lin, Synthesis, crystal struc-
ture and fluorescence of two novel mixed-ligand cadmium coordination poly-
mers with different structural motifs, Eur. J. Inorg. Chem. 14 (2003) 2705–2710;
(c) Y.J. Cui, Y.F. Yue, G.D. Qian, B.L. Chen, Luminescent functional metal–organic
frameworks, Chem. Rev. 112 (2012) 1126–1162.
[8] (a) Z.-M. Sun, J.-G. Mao, Y.-Q. Sun, H.-Y. Zeng, A. Clearfield, synthesis, characteriza-
tion, and crystal structures of three new divalent metal carboxylate-sulfonates
with
a layered and one-dimensional structure, Inorg. Chem. 43 (2004)
336–341;
(b) H.B. Abourahma, B. Moulton, V. Kravtsov, M.J. Zaworotko, Supramolecular
isomerism in coordination compounds: nanoscale molecular hexagons and
chains, J. Am. Chem. Soc. 124 (2002) 9990–9991.