Unusual Cd2(COO)4Cl2 building blocks for the construction of a dia or ths-type metal-organic framework

Article abstract of DOI:10.1016/j.inoche.2012.02.007

A new three-dimensional (3D) metal-organic framework (MOF) [Cd(tpa)Cl](CH₃)₄ N⁺ (1; tpa = 1, 4-terephthalic acid) with unusual Cd₂ (COO)₄Cl₂ building block has been solvothermally synthesized and structurally characterized by the aid of single crystal X-ray diffraction, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) Elemental analysis (EA) and Infrared Spectroscopy (IR). The Cd₂(COO)₄Cl₂ building block can be simplified as 4-connected or two 3-connected nods in different ways, correspondingly, the compound 1 exhibits 4-connected dia or 3-connected ths structural topology.

Full text of DOI:10.1016/j.inoche.2012.02.007

Inorganic Chemistry Communications 20 (2012) 30–32
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Unusual Cd2(COO)4Cl2 building blocks for the construction of a dia or ths-type
metal-organic framework
b
b,
a,⁎⁎
⁎
, Yao Kang , Fei Wang
Hui Yang a,b, Tie hu Li
a
School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 35002, China
b
a r t i c l e i n f o
a b s t r a c t
A new three-dimensional (3D) metal-organic framework (MOF) [Cd(tpa)Cl](CH3)4 N+ (1; tpa=1, 4-
terephthalic acid) with unusual Cd2 (COO)4Cl2 building block has been solvothermally synthesized and struc-
turally characterized by the aid of single crystal X-ray diffraction, powder X-ray diffraction (PXRD), thermo-
gravimetric analysis (TGA) Elemental analysis (EA) and Infrared Spectroscopy (IR). The Cd2(COO)4Cl2
building block can be simplified as 4-connected or two 3-connected nods in different ways, correspondingly,
the compound 1 exhibits 4-connected dia or 3-connected ths structural topology.
Article history:
Received 12 January 2012
Accepted 14 February 2012
Available online 22 February 2012
Keywords:
Metal-organic framework
Cadmium
© 2012 Elsevier B.V. All rights reserved.
Topology
SBUs
Crystal structure
Metal-organic frameworks (MOFs) or porous coordination poly-
mers (PCPs) have recently attracted considerable interest not only
for their potential applications in gas storage, separation, sensing
and heterogeneous catalysis, but also for fascinating architectures
and intriguing topologies [1,2]. The architectures of MOFs are mainly
depended on the assembly of metals and linkers. The molecular sec-
ondary building units (SBUs) are essential to the design of direction-
ality for the construction of MOFs and to the achievement of robust
frameworks [3]. SBUs usually not only have predefined and often
rigid coordination geometries, but also always generated in situ,
which often provides a versatile pool of connectors for the rational
synthesis of targeted MOFs [4].
It is noteworthy that SBUs also play an important role in the struc-
tural design and synthesis of metal-carboxylate frameworks. Indeed,
some famous framework materials such as MOF-5, MIL-101 and
HKUST-1 etc., are all based on the assembly of metals and carboxylate
ligands [1a,5]. In MOF-5, a cationic oxide-centered Zn4O tetrahedron
is edge-bridged by six carboxylates to give the neutral octahedron-
shaped SBU that reticulates into a three-dimensional (3D) cubic po-
rous network with pcu type topology [5a]. The design idea of MIL-
101 is that leading to the existence of trimeric inorganic building
blocks consists of three metal octahedra, each coordinated by
four bridging carboxylate groups sharing a μ3-O common vertex
[CrIII3O(CO2)6] [1a]. Simulations were then performed to combine
these inorganic trimers in 3D space with 1, 3, 5-benzene tricarboxy-
late (btc) through the assembly of a computationally designed hybrid
building block. HKUST-1 is formed by binuclear paddle-wheel units
[Zn2(CO2)4] linked by four btc Ligands, connected into a (3, 4)-
connected tbo type topology [5b]. Through the building block ap-
proach and the reticular synthesis strategy, many analogues famous
frameworks can be designed and synthetic.
In this work, we reported the synthesis and structure and photolu-
minescence (PL) of a new compound [Cd(tpa)Cl](CH3)4 N+ (1;
tpa=1, 4-terephthalic acid) with unusual Cd2 (COO)4Cl2 building
block synthesized under solvothermal condition. The Cd2(COO)4Cl2
building block can be simplified as 4-connected or two 3-connected
nods in different ways, correspondingly, the compound 1 exhibits 4-
connected dia or 3-connected ths structural topology.
Compound
1 was solvothermally synthesized by employing
CdCl2·3H2O, 1, 4-terephthalic acid (H2tpa), and (CH3)4NBr in N, N’-
Dimethylformamide (DMF) solvent at 120 °C for 3 days [6]. Single-
crystal X-ray diffraction analysis reveals that compound 1 crystallizes
in the centrosymmetric orthorhombic space group Fddd and pos-
sesses an extended 3D framework [7]. The asymmetric unit of 1 in-
cludes one half Cd2+ center, one half tpa ligand, one half chlorine
anion, and one half (CH3)4 N+ cation (Fig. 1a). In the structure of 1,
the Cd atom adopts distorted octahedral geometry coordinated by
four oxygen atoms from two carboxylate groups of two tpa ligands
and two chlorine atoms. The Cd–O distances are ranging from
2.314(3) to 2.374(3) Å, and the Cd–Cl distance is 2.5596(12) Å.
Three carboxylate groups of the tpa ligand adopt chelating coordina-
tion mode, which link two Cd atoms (Fig. 1c). Two Cd ion are bridged
by two chlorine atoms and chelated by four carboxylate groups into
⁎
Correspondence to: F. Wang, State Key Laboratory of Structural Chemistry, Fujian
Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou,
Fujian, 35002, China.
⁎⁎ Correspondence to: T. Li,School of Materials Science and Engineering, Northwest-
ern Polytechnical University, Xi'an 710072, China.
E-mail address: wangfei04@fjirsm.ac.cn (F. Wang).
1387-7003/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2012.02.007

H. Yang et al. / Inorganic Chemistry Communications 20 (2012) 30–32
31
Fig. 1. (a) The independent unit of 1; (b) The dinuclear unit in 1; (c) View of the single open framework in 1 along b axis, showing large channels; (d) View of the 3D framework of 1
along b axis, showing three-fold interpenetration of the network.
an symmetrical dinuclear unit Cd2(COO)4Cl2 (Fig. 1b). Here the Cd…
Cd distance is 3.6670(1) Å. The resulting dinuclear units are further
connected by the tpa ligands to form a anion three-dimensional
(3D) framework with interesting oval nanotube channels, in which
the (CH3)4 N+ cations fill the free spaces and also balance the
whole charges (Fig. 1c). Furthermore, three such frameworks are
mutually interpenetrated (Fig. 1d).
An interesting structural feature of 1 is the presence of the 4-
connected dia or 3-connected ths topology network in different
ways. Topological analysis was performed by Topos4.0 [8]. The sym-
metrical dinuclear unit Cd2(COO)4Cl2 units can be viewed as 4-
connected nodes, and the btc ligand can be reduced as a line (L)
(Fig. 2a). Therefore, the three-fold interpenetration 3D framework
of 1 can be simplified as a 4-connected dia net (Fig. 2b). Just consid-
ering the Cd atom as the node, the symmetrical dinuclear unit Cd2(-
COO)4Cl2 units can be viewed as two 3-connected nodes showing
Fig. 2c, thus the 3D framework of 1 can be simplified as a 3-
connected ths net (Fig. 2d).
The as-synthesized samples of 1 have been characterized by powder
X-ray diffraction (PXRD) (Figure S1). The experimental PXRD patterns
correspond well with the results simulated from the single crystal
data, indicating the pure phase of 1. The difference in reflection intensi-
ties between the simulated and experimental patterns was due to the
variation in preferred orientation of the powder samples during the
collection of the experimental PXRD data.
Thermogravimetric analysis (TGA) in N2 atmosphere with a heat-
ing rate of 10 °C/min was performed on polycrystalline sample to de-
termine their thermal stability from 25 to 800 °C. The result indicated
that the host framework was stable up to ca. 290 °C (Figure S2). After
that temperature, the framework decomposed.
The emission spectrum of 1 was measured in the solid state at
room temperature. It exhibited one intense emission at 437 nm
upon photoexcitation at 350 nm (Fig. 3). In comparison, the intense
emission of the free H2tpa ligand was at 385 nm. So the emission
bond of 1 may be attributed to the ligand centered charge transfer
(n→π* or π→π*).
Fig. 2. (a) The defined 4-connected nodes; (b) Topologically representation of three
interpenetrating dia nets of 1; (c) The defined 3-connected nodes; (d) Topologically
representation of three interpenetrating ths nets of 1.
Fig. 3. Solid-state emission spectra of 1 and free H2tpa ligand at room temperature.

32
H. Yang et al. / Inorganic Chemistry Communications 20 (2012) 30–32
(f) Y.-J. Cui, Y.-F. Yue, G.-D. Qian, B.-L. Chen, Luminescent functional metal–organic
In summary, we presented here a new 3-fold interpenetration
frameworks, Chem. Rev. (2011), doi:10.1021/cr200101d.
metal organic framework with 4-connected dia or 3-connected ths
structural topology based on the Cd2(COO)4Cl2 building blocks. The
compound exhibited interesting topology and photoluminescent
property. These results demonstrated that the building blocks played
an important role in the structure design and synthesis.
[3] D.J. Tranchemontagne, J.L. Mendoza-Corte, M. O'Keeffe, O.M. Yaghi, Secondary
building units, nets and bonding in the chemistry of metal–organic frameworks,
Chem. Soc. Rev. 38 (2009) 1257–1283.
[4] (a) X.-C. Huang, Y.-Y. Lin, J.P. Zhang, X.-M. Chen, Ligand-directed strategy for
zeolite-type metal-organic frameworks: zinc(ii) imidazolates with unusual
zeolitic topologies, Angew. Chem. Int. Ed. 45 (2006) 1557–1559;
(b) A. Phan, C. Doonan, F.J. Uribe-Romo, C.B. Knobler, M. O'keeffe, O.M. Yaghi, Syn-
thesis, structure, and carbon dioxide capture properties of zeolitic imidazolate
frameworks, Acc. Chem. Res. 43 (2009) 58–67;
Acknowledgments
(c) Sh.-T. Zheng, J.-J. Bu, T. Wu, C. Chou, P.-Y. Feng, X.-H. Bu, Porous indium–or-
ganic frameworks and systematization of structural building blocks, Angew.
Chem. Int. Ed. 50 (2011) 1–6.
This work is supported by NSFC (21103189 and 21173224) and
NSF of Fujian Province (2010J05039).
[5] (a) H.-L. Li, M. Eddaoudi, M. O'Keeffe, O.M. Yaghi, Design and synthesis of an ex-
ceptionally stable and highly porous metal-organic framework, Nature 402
(1999) 276–279;
Appendix A. Supplementary data
(b) S.S.Y. Chui, S.M.F. Lo, J.P.H. Charmant, A.G. Orpen, I.D. Williams, A chemically
functionalizable nanoporous material [Cu3(TMA)2(H2O)3]n, Science 283
(1999) 1148–1150.
Supplementary data to this article can be found online at doi:10.
1016/j.inoche.2012.02.007.
[6] Synthesis of [Cd(tpa)Cl] (CH3)4N (1): CdCl2·6H2O (0.154 g, 0.5 mmol), (CH3)
4NBr (0.077 g, 0.5 mmol), 1, 4-terephthalic acid (H2tpa, 0.86 g, 0.5 mmol) and
5 mL N, N-dimethylformamide (DMF) in a 23 mL Teflon-lined airtight reactor
was heated at 120 °C for 3 days, and then cooled to room-temperature, colorless
crystals of 1 were obtained (0.125 g, 65% yield). Elemental analysis (EA) for 1,
C12H16NClO4Cd (386.1): Calcd. C 37.33, H 4.18, N 3.63, Cl 9.18. Found. C 37.31,
References
[1] (a) G. Férey, Hybrid porous solids: past, present, future, Chem. Soc. Rev. 37 (2008)
191–214;
H
4.19, N 3.61, Cl 9.17. IR (KBr pellet, cm-1): 3035(w), 1688(s), 1554(s),
(b) J.R. Long, O.M. Yaghi, The pervasive chemistry of metal-organic frameworks,
Chem. Soc. Rev. 38 (2009) 1213–1214;
1504(w), 1488(w), 1439(w), 1382(s), 1299(w), 1146(w), 1091(m), 1012(m),
952(s), 903(w), 883(m), 841(s), 745(s), 663(w), 525(s), 456(w).
(c) J.-R. Li, R.J. Kuppler, H.-C. Zhou, Selective gas adsorption and separation in
metal-organic frameworks, Chem. Soc. Rev. 38 (2009) 1477–1504;
(d) D.M. D'Alessandro, B. Smit, J.R. Long, Carbon dioxide capture: prospects for
new materials, Angew. Chem. Int. Ed. 49 (2010) 6058–6082;
(e) S.R. Caskey, A.J. Matzger, Selective metal substitution for the preparation of
heterobimetallic microporous coordination polymers, Inorg. Chem. 47
(2008) 7942–7944.
[7] Crystal data for a: C12H16NClO4Cd, Mw=386.1, cubic, a=15.0412(4)
Å
b=15.8919(4) c=28.2210(7) Å, α=β=γ=90.00° V=6745.8(3) Å3,
Å
T=273(2) K, space group Fddd, Z=16, 14769 reflections measured, 2461 indepen-
dent reflections (Rint=0.1087). The final R1 values were 0.0533 (I>2σ(I)). The
final wR(F2) values were 0.1508 (I>2σ(I)). The final R1 values were 0.0758 (all
data). The final wR(F2) values were 0.1673 (all data). The goodness of fit on F2 was
1.097.
[2] (a) O.M. Yaghi, M. O'Keeffe, N.W. Ockwig, H.K. Chae, M. Eddaoudi, J. Kim, Reticular
synthesis and the design of new materials, Nature 423 (2003) 705–715;
(b) S. Kitagawa, R. Kitaura, S. Noro, Functional Porous Coordination Polymers,
Angew. Chem. Int. Ed. 43 (2004) 2334–2375;
[8] (a) V.A. Blatov, A.P. Shevchenko, V.N. Serezhkin, Crystal space analysis by means
of Voronoi–Dirichlet polyhedra, Acta Crystallogr. A51 (1995) 909–916;
(b) V.A. Blatov, L. Carlucci, G. Ciani, D.M. Proserpio, Interpenetrating metal-organic
and inorganic 3D networks: a computer-aided systematic investigation. Part I.
(c) X. Lin, J. Jia, X. Zhao, K.M. Thomas, A.J. Blake, G.S. Walker, N.R. Champness, P.
Hubberstey, M. Schröder, High H2 adsorption by coordination-framework
materials, Angew. Chem. Int. Ed. 45 (2006) 7358–7364;
(d) Y. Liu, F. Boey, L.L. Lao, H. Zhang, X. Liu, Q. Zhang, Postchemistry of inorganic–
organic hybrid particles in aqueous solution: metal–cation exchange, Chem.
Asian J. 6 (2011) 1004–1006;
Analysis of the Cambridge Structural Database, CrystEngComm
6 (2004)
377–395;
(c) V.A. Blatov, D.M. Proserpio, Topological relations between three-periodic nets.
II. Binodal nets, Acta Crystallogr. A65 (2009) 202.
(e) B.-L. Chen, S.-G. Xiang, G.-D. Qian, Metal–organic frameworks with functional
pores for recognition of small molecules, Acc. Chem. Res. 43 (2010) 1115–1124;