1D zigzag chain and 0D monomer Cd(II)/Zn(II) compounds based on flexible phenylenediacetic ligand: Synthesis, crystal structures and fluorescent properties

Article abstract of DOI:10.1016/j.molstruc.2008.05.039

Three novel Cd(II)/Zn(II) compounds, [Cd₂(poda)₂(phen)₃(H₂O)]_n·nEtOH·3nH₂O(1), [Zn(poda)₂(bpy)(H₂O)]_n(2) and [Zn(Hpoda)₂(bpy)](3) (H₂poda = 1,2-phenylenediacetic acid, phen = 1,10-phenanthroline, bpy = 2,2′-bipyridyl), have been synthesized and characterized by IR, TG, fluorescent spectrum and single-crystal X-ray diffraction techniques. In 1, poda^2- anions link the adjacent Cd(II) centers to generate a 1D zigzag chain. Furthermore, an unprecedented four-footed 8-shaped mixed water-ethanol (H₂O)₆(C₂H₅OH)₂ cluster connects four double chains based on 1D zigzag chain into 3D supramolecular architecture. By bis(chelate-monodentate) fashion of poda^2- ligand, compound 2 exhibits 1D zigzag chains, which forming a dense zipper-like 2D structure via strong π-π stacking interactions. Differed from 1 and 2, compound 3 has a mononuclear motif, and displays a 3D 6-connected α-Po net hydrogen-bonded topology. The structure-related solid-state fluorescence spectra of compounds 1 and 2 have been determined.

Full text of DOI:10.1016/j.molstruc.2008.05.039

Journal of Molecular Structure 892 (2008) 283–288
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
1D zigzag chain and 0D monomer Cd(II)/Zn(II) compounds based on flexible
phenylenediacetic ligand: Synthesis, crystal structures and fluorescent properties
a
a
b
Fang Yang a, Yixia Ren a, Dongsheng Li a, , Feng Fu , Guangcai Qi , Yaoyu Wang
*
a Department of Chemistry and Chemical Engineering, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan0an University, Yan0an, Shaanxi 716000, China
b Department of Chemistry, Northwest University, Xi0an, Shaanxi 710069, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 9 April 2008
Received in revised form 23 May 2008
Accepted 27 May 2008
Available online 6 June 2008
Three novel Cd(II)/Zn(II) compounds, [Cd2(poda)2(phen)3(H2O)]nꢀnEtOHꢀ3nH2O(1), [Zn(poda)2(bpy)
(H2O)]n(2) and [Zn(Hpoda)2(bpy)](3) (H2poda = 1,2-phenylenediacetic acid, phen = 1,10-phenanthroline,
bpy = 2,20-bipyridyl), have been synthesized and characterized by IR, TG, fluorescent spectrum and sin-
gle-crystal X-ray diffraction techniques. In 1, poda2ꢁ anions link the adjacent Cd(II) centers to generate a
1D zigzag chain. Furthermore, an unprecedented four-footed ‘‘8-shaped” mixed water–ethanol
(H2O)6(C2H5OH)2 cluster connects four double chains based on 1D zigzag chain into 3D supramolecular
architecture. By bis(chelate–monodentate) fashion of poda2ꢁ ligand, compound 2 exhibits 1D zigzag chains,
Keywords:
Cd(II)/Zn(II) phenylenediacetic compounds
Crystal structure
Mixed water–ethanol clusters
Fluorescent properties
which forming a dense zipper-like 2D structure via strong
compound 3 has a mononuclear motif, and displays a 3D 6-connected
p
–
p
stacking interactions. Differed from 1 and 2,
-Po net hydrogen-bonded topology.
a
The structure-related solid-state fluorescence spectra of compounds 1 and 2 have been determined.
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
have been widely investigated for the larger distance of their two
carboxylate groups, and are apt to porous metal compounds [10].
Construction of metal-involved supramolecular architectures
based on crystal engineering are currently of interest in the field
of supramolecular chemistry and material science [1,2]. The
increasing interest in this field is justified not only by their poten-
tial application in microelectronics [3], non-linear optics [4], por-
ous materials [5], catalysis, and luminescence [6], but also by
their intriguing structural diversities of the architectures [7]. A suc-
cessful approach to build these supramolecular frameworks is to
select suitable multi-dentate ligands as building blocks. Among
them, multi-carboxylate ligands have been demonstrated as a
top-rank candidates, owing to their versatile coordination modes
[8], for the formation of 1D, 2D or 3D frameworks and, construction
of unique interwoven extended structural motifs, such as polyca-
tenanes, polyrotaxanes, double helices, triple helices, borromean
rings, molecular braids, and other more unusual species [9]. Pheny-
lenediacetic acid is a multifunctional ligand with two carboxyl
groups, which possesses three isomers of 1,2-, 1,3-, and 1,4-pheny-
lenediacetitic acids. As symmetrical and flexible dicarboxylate li-
gand, they could display versatile coordinated modes, and
However, 1,2-phenylenediacetitic acid is rarely reported [11],
which inspirits our interest in it. Recently, we take interest in
building supramolecular structures using N-heterocyclic or aro-
matic carboxyl ligands, and obtain the expected results.
In view of above points, we tried to prepare Cd(II)/Zn(II) com-
pounds with 1,2-phenylenediacetitic acid for series researches. For-
tunately, we obtained two 1D compounds (1 and 2) and 0D
mononuclear compound 3 by using 1,2-phenylenediacetitic acid as
bridged ligand and NN chelated ligands as terminal ligands. In these
compounds, 1,2-phenylenediacetitic acid exhibits three kinds of
coordination fashions, and constructs 1D zigzag chain or 0D mono-
mer structures, respectively. Interestingly, compound 1 shows a
3D supramolecular architecture with the inclusion of an unusual
four-footed ‘‘8-shaped” mixed water–ethanol (H2O)6(C2H5OH)2
clusters unreported in Ref. [12].
2. Experimental
2.1. Materials and measurements
provide potential identified sites of hydrogen bonds and p–p stack-
ing interactions to expand in high dimension frameworks. To our
knowledge, two of them, 1,3- and 1,4-phenylenediacetitic acids,
All manipulations were carried out in air. All reagents were
commercially available and were used without further purification.
Elemental analyses (C, H, N) were performed on a Perkin-Elmer
2400 CHN elemental analyzer. TG analyses were recorded with a
NETZSCH STA 449C microanalyzer under nitrogen atmosphere at
* Corresponding author.
E-mail address: lidongsheng1@126.com (D. Li).
0022-2860/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2008.05.039

284
F. Yang et al. / Journal of Molecular Structure 892 (2008) 283–288
a heating rate of 10 °C minꢁ1. Fluorescence spectra were performed
on a Hitachi F-4500 fluorescence spectrophotometer at room
temperature.
two nitrogen atoms from one phen, and one water molecule into
a distorted one-cap triangular-prism geometry. The Cd–O bonds
are in the range of 2.208–2.585 Å, Cd–N bonds range from
2.374(4) to 2.468(4) Å, which drop into the normal scope of Cd–
N and Cd–O bond lengths [16]. The poda2ꢁ ligand adopts che-
late–bidentate coordination fashion to connect the adjacent CdII
atoms into 1D zigzag chain. Interestingly, the 1D chains are inter-
linked to form a 1D double chain via strong intermolecular hydro-
gen bonds between the coordinated water molecules on one chain
and the poda2ꢁ acceptors on the other chain (O(9)–
Hꢀ ꢀ ꢀO(3) = 2.730 Å, 178.49°).
2.2. Synthesis of [Cd2(poda)2(phen)3(H2O)]nꢀnEtOHꢀ3nH2O (1)
A solution of H2poda (0.0194 g, 0.1 mmol) and phen (0.0198 g,
0.2 mmol) in EtOH/H2O (40 mL, 1:1) adjusted to pH 7 by addition
of aqueous NaOH solution (1.0 mmol Lꢁ1), was added to the solu-
tion of Cd(NO3)2ꢀ4H2O (0.0308 g, 0.1 mmol) in H2O (20 mL). The
reaction mixture was stirred for ca. 10 min to give a colorless solu-
tion and filtered. After the mixture was slowly cooled to room tem-
perature, colorless block crystals of 1 were yielded. Elemental
analysis calcd. for C58H54Cd2N6O13 (%): C, 54.94; H, 4.29; N, 6.63.
Found (%): C, 54.02; H, 4.12; N, 6.05.
The most remarkable feature of 1 is the existence of unreported
mixed solvent clusters (Fig. 2a). The solvent cluster, as named four-
footed ‘‘8-shaped” mixed water–ethanol (H2O)6(C2H5OH)2 cluster,
consists of four water (O11A, O13A, O11B, and O13B) and two oxy-
gen atoms (O12A and O12B) of two ethanol molecules as the ‘‘8-
shaped” main body, as well as two water molecules (O10A and
O10B) and –CH2–CH3 groups of ethanol molecules as its four feet
(Fig. 2b). All data of these hydrogen bonds are listed in Table 2.
The distances of hydrogen bonds range from 2.651 to 2.875 Å, with
the mean value of 2.786 Å, which is slightly longer than that ob-
served in ice-like cyclic (H2O)8 clusters [17]. Although discrete
water clusters have been the subject of theoretical calculations,
and have been described in literatures [18,19], mixed solvent clus-
ters have been rarely reported before [20]. As far as we know, such
a four-footed ‘‘8-shaped” mixed water–ethanol (H2O)6(C2H5OH)2
cluster is rare example and worth to investigating further. In com-
pound 1, each mixed solvent cluster links four double chains by its
four feet to extend into 3D supramolecular framework.
2.3. Synthesis of [Zn(poda)2(bpy)(H2O)]n (2)
Compound 2 was synthesized from the reaction mixture of
H2poda (0.0194 g, 0.1 mmol) were dissolved in 2 ml of MeOH, then
the solution was added dropwise with 6 ml H2O of Zn(NO3)2
(0.0308 g, 0.1 mmol) and 2 ml MeOH of bpy (0.0156 g,0.1 mmol).
The solution was adjusted to pH 8–9 by addition of 1.0 mmol Lꢁ1
NaOH solution, then stirred, filtered, and standing in air at room
temperature for 20 days, some colorless block crystals of com-
pound
2
were obtained. Elemental analysis calcd. for
C20H18N2O5Zn (%): C, 55.64; H, 4.20; N, 6.49. Found (%): C, 54.93;
H, 4.01; N, 5.69.
2.4. Synthesis of [Zn(Hpoda)2(bpy)] (3)
In compound 2, the Zn(II) ion lies in a distorted octahedron
coordination environment. The coordinated six atoms are three
carboxylic O atoms from two poda2ꢁ ligands, one O atom from
one water molecule and two N atoms of a bpy ligand, respectively
(Fig. 3). The bond lengths of Zn–O are in the range of 2.2086–
2.3591 Å, and those of Zn–N within 2.3129–2.3212 Å, which accord
with the Zn–O and Zn–N bond lengths reported [21]. Just for the
flexible structure of the poda2ꢁ ligand, the adjacent Zn(II) ions
are linked into an infinite 1D zigzag chain by the poda2ꢁ anions
in a bis(chelate–monodentate) mode (Fig. 4). The chelating bpy li-
gands coordinated to Zn(II) ions at the opposite side to the phenyl
The synthesis procedure was similar to that described above
compound 2 except using pH 7 instead of pH 8–9, and colorless
block crystals of 3 were yielded. Elemental analysis calcd. for
C30H26N2O8Zn (%): C, 59.27; H, 4.31; N, 4.61. Found (%): C, 58.76;
H, 4.12; N, 3.95.
2.5. Determination of crystal structure
Single-crystal X-ray data were collected on a Bruker SMART
APEX II CCD diffractometer equipped with graphite monochroma-
tized Mo Ka (k = 0.071073 nm) by Crystal clear software. Empirical
of the poda2ꢁ ligand of 1D zigzag chain alternately. Strong
p–p
stacking interactions (the face to face distance is 3.493 Å) existing
between the immediate bipy ligands and phenyl rings of poda2ꢁ li-
gands from adjacent chains, result in a dense zipper-like 2D layer
in ac plane (Fig. 5). Then, these 2D layers stack along b axis accord-
ing to ABAB manner.
absorption corrections were applied in the case. All calculations
were conducted using SHELXS-97 and SHELXL-97 programs
[13,14], while the structures were solved by the direct methods.
All the non-hydrogen atoms were located from the trial structure
and then refined anisotropically with SHELXTL via full-matrix
least-square procedure [15]. Hydrogen atoms were located from
difference Fourier maps. The crystallographic data of the com-
pounds are summarized in Table 1.
The coordination modes of an organic ligand containing car-
boxyl group are affected by pH value of a reaction system. In order
to verify it, we altered pH value of system of compound 2 from 8–9
to 7 and obtained compound 3. For 3, the Zn(II) ion is in a six-coor-
dinated slight distorted triangular-prism environment, in which
four oxygen atoms O1, O2, O1A, and O2A from two Hpodaꢁ ligands,
and two nitrogen atoms N1 and N1A from a bpy ligand (Fig. 6). And
O1, O2A, N1A, and O1A, O2, N1 form two planes of
triangular-prism. The Zn–O bond lengths are in the range of
2.2568–2.3515 Å, which are similar to those in compound 2. The
Zn–N distances (2.2530 Å) are slightly shorter than that in com-
pound 2. The Hpodaꢁ ligand adopts the chelate coordinated mode
and holds back the formation of 1D chain.
A notable feature of compound 3 is four neighboring Zn(II) ions
via four C12–Hꢀ ꢀ ꢀO2 hydrogen bonds (3.453 Å, 115.42°) to form 2D
[4,4] supramolecular network parallel to the ab plane (Fig. 7). And
strong hydrogen bonds between the protonized carbonyl oxygen
atoms from two different dangling ligands (O4–Hꢀ ꢀ ꢀO1 2.667 Å)
make 2D networks into 3D 6-connected supramolecular edifice
[22]. From the point of view of topology, 3D framework of 3 is a
3. Results and discussion
3.1. Crystal structures of compounds 1–3
X-ray single-crystal diffraction analysis reveals compound 1 has
1D zigzag structure based on dinuclear metallic units containing
solvent clusters. In the asymmetric unit of 1, there are two CdII
ions, two poda2ꢁ ligand, three phen groups, one water molecule,
as well as three lattice water molecules, and one ethanol molecule
(Fig. 1). Cd1 ion is located in a six-coordinated anti-triangular-
prism geometry with four nitrogen atoms from two chelated phen
ligands, two oxygen atoms from two poda2ꢁ groups (plane 1: N4,
N2, O5 and plane 2: O1, N1, N3). Different from Cd1, Cd2 ion is se-
ven-coordinated to four oxygen atoms from two poda2ꢁ groups,

F. Yang et al. / Journal of Molecular Structure 892 (2008) 283–288
285
Table 1
Crystallographic data for compounds 1, 2, and 3
1
2
3
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C58H54N6O13Cd2
1267.87
Triclinic
C20H18N2O5Zn
431.73
Monoclinic
P2(1)/n
10.2100(17)
17.054(3)
11.1836(18)
90
95.296(2)
90
C30H26N2O8Zn
607.9
Monoclinic
C2/c
16.398(4)
8.6224(18)
20.785
P-1
12.7635(17)
14.9031(19)
15.198(2)
68.796(2)
84.210(3)
78.093(2)
2636.2(6), 2
2.023
b (Å)
c (Å)
a
(deg)
90
b (deg)
111.975(2)
90
2725.28(242), 2
1.48151
c
(deg)
V (Å3), Z
1938.99(67), 4
1.47883
1.30
Dcacl (g cmꢁ3
l
)
(mmꢁ1
)
1.725
0.96
F(000)
1288
888.0
1256.0
Reflections collected/unique
13806/9133
0.0258
1.039
0.0405/0.0747
0.0751/0.0910
0.746/ꢁ0.619
16329/3529
0.0344
1.088
0.0642/0.1544
0.0513/0.1413
0.943/ꢁ0.426
12711/2536
0.0242
1.135
0.0649/0.2163
0.0590/0.2072
1.102/ꢁ0.512
Rint
Goodness-of-fit on F2
b
R1a/wR2 [I > 2
r(I)]
R1/wR2 [all data]
Largest differ. peak and hole (e Åꢁ3
)
Fig. 1. ORTEP plot showing the asymmetric unit of compound 1.
Fig. 2. 3D framework via ‘‘8-shaped” four-footed mixed solvent clusters along a axis in 1 (carbon atoms of 1,10-phen and hydrogen atoms are omitted for clarity).
distorted
a-Po net with the Zn(II) ions as nodes and hydrogen
In compounds 1–3, H2poda ligand adopts three different
bonds as spacers (9.263 ꢂ 9.263 ꢂ 11.052 Å) (Fig. 8).
coordination modes: (1) bis(chelate–bidentate) mode; (2)

286
F. Yang et al. / Journal of Molecular Structure 892 (2008) 283–288
Table 2
served weight loss of 5.11% is somehow larger than the calculated
value; however, we deem that this is within the experimental error
because the results of TG may have larger errors. The secondary
step (90–430 °C) corresponds to the release of bpy ligands, giving
zinc oxides as the final decomposition product which constitute
18.32% (calcd. 18.85%). For 3, TG curve shows merely one step of
weight loss from 20 to 489 °C, and zinc oxides is the final decom-
position product with residue percent of 13.26% (calcd. 13.39%).
Hydrogen-bond distances and angles of the mixed solvent cluster in 1
D–H
d(Hꢀ ꢀ ꢀA)/nm
\DHA/deg
d(Dꢀ ꢀ ꢀA)/nm
A
O(9)–H(9C)
O(9)–H(9C)
0.1870
0.1880
0.2078
0.1913
0.2045
0.1957
0.1957
0.1971
0.2151
178.49
178.42
165.14
164.79
164.78
164.63
169.28
136.38
137.31
0.2719
0.2730
0.2908
0.2742
0.2874
0.2786
0.2767
0.2652
0.2835
O(2)
O(3)
O(1)
O(6)
O(12)
O(10)
O(7)
O(11)
O(12)
O(10)–H(10A)
O(10)–H(10B)
C(11)–H(11A)
O(11)–H(11B)
O(12)–H(12)
O(13)–H(13A)
O(13)–H(13B)
3.3. Fluorescent properties of 1 and 2
As shown in Fig. 10, solid-state fluorescence spectra of L and 1, 2
at room temperature have been determined. The free ligand L has
fluorescence emission bands centered at ca. 391.8 nm. In compari-
son with that of the free ligand, compound 1 shows weak red-shifted
emission centered at 566 nm (kex = 350 nm), which could be as-
cribed to the ligand-to-metal-charge-transfer (LMCT), that is, prob-
ably due to r-donations from the cooperation of H2poda and phen
ligands to the CdO core [23]. The similar emission at 375 nm was ob-
served for 2 upon excitation at 220 nm. Compared to that of L, the
maximum emission band of 2 is blue-shift shifted. It is electronic
that the emission of 2 originated from the
p ? p
* electronic transi-
tion of L ligand [24]. By comparing the emission spectra of 2 and li-
gand, we could conclude that the enhancement of luminescence in
2 may be attributed to the rigidity of 2. This rigidity is favor of energy
transfer and reduces the loss of energy through a radiationless path-
way. The possible explanation for the different emission properties
of 1 and 2 is the different structure in 1 and 2. Because compound
2 are usually stable and insoluble in common solvents arising from
their polymeric structures, it is possible to develop high stable lumi-
nescent materials based on them.
Fig. 3. The coordination environment of Zn in compound 2.
bis(chelate–monodentate) mode and (3) mono(chelate–deproton-
ized) mode. These different modes make their different structures.
From compounds 2 and 3, we could discover that pH value of the
reaction system plays a key role in constructing the structures of
the compounds. Clearly, the pH value influence in the compounds
is attributed to its effect on deprotonation of H2poda ligand.
3.2. Thermal stabilities of compounds 1–3
Thermogravimetric analyses (TG) have been performed in air
for compounds 1–3 from 20 to 700 °C (Fig. 9). For compound 1,
its TG curve shows two main steps of weight losses. The first step
started at 40 and completed at 80 °C, which corresponds to the re-
lease of one free C2H5OH and four H2O. The observed weight loss of
9.77% is close to the calculated value (9.32%). The final step (310–
476 °C) corresponds to the release of bpy and H2poda ligands, giv-
ing cadmium oxides as the final decomposition product which con-
stitute 20.47% (calcd. 20.25%). TG curve of 2 also exhibit two main
steps of weight losses. The first step started at 31 °C and completed
at 87 °C, which corresponds to the release of one H2O. The ob-
Fig. 5. 2D zipper-like network via p–p stacking interactions of 2.
Fig. 4. 1D chain along b axis in compound 2.

F. Yang et al. / Journal of Molecular Structure 892 (2008) 283–288
287
Fig. 6. The coordination environment of Zn(II) in 3.
Fig. 9. TG curves of compounds 1–3.
Fig. 7. The view of altemation of 2 along the ab plane (carbon atoms and hydrogen
atoms of O-phenylenediacetic acid and hydrogen atoms are omitted for clarity).
Fig. 10. Emission spectra of 1, 2, and free ligand H2poda (L) in solid-state at room
temperature.
(fax: +44 1233 336033; e-mail: deposit@ccdc.cam.ac.uk or
http:www.ccdc.cam.ac.uk) and can be obtained on request, quot-
ing the deposition Nos. 683323, 683324, and 683325.
Fig. 8. The schematic topology of the compressed a-Po net in 3.
Acknowledgments
This project was supported by the National Natural Science
Foundation of China (No. 20773104), the Program for New Century
Excellent Talents in University (NCET-06-0891), the Natural Sci-
ence Foundation of Shaanxi Provinces of China (No. 2006B08)
and the Nature Scientific Research Foundation of Shaanxi Provin-
cial Education Office of China (No. 06JK155).
4. Conclusions
In summary, using H2poda ligand and NN chelated ligands, we
isolated three metal (Cd/Zn)–organic compounds with 1D chains
(1 and 2) and 0D monometer (3) structures. Noteworthy, in 1 an
unprecedented four-footed ‘‘8-shaped” mixed water–ethanol
(H2O)6(C2H5OH)2 cluster links adjacent 1D double chains and ex-
tends 1 into 3D structures, and is one of rare mixed solvent cluster
examples in metal–organic coordination polymer research.
References
[1] [a] S.T. Wu, L.S. Long, R.B. Huang, L.S. Zheng, Cryst. Growth Des. 7 (2007) 1746;
[b] M. Du, Z.H. Zhang, L.F. Tang, X.J. Zhao, S.R. Batten, Chem. Eur. J. 13 (2007)
2578.
[2] [a] O.M. Yaghi, M. O’ Keeffe, N.W. Ockwig, H.K. Chae, M. Eddaoudi, J. Kim,
Nature 423 (2003) 705;
5. Supplementary material
[b] M. Du, X.J. Jiang, X.J. Zhao, Inorg. Chem. 46 (2007) 3984;
[c] A.Y. Robin, K.M. Fromm, Coord. Chem. Rev. 250 (2006) 2127.
[3] X.L. Wang, C. Qin, E.B. Wang, L. Xu, Z.M. Su, C.W. Hu, Angew. Chem. 116 (2004)
5146.
Supplementary data are available from the Cambridge Crystal-
lographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK

288
F. Yang et al. / Journal of Molecular Structure 892 (2008) 283–288
[4] [a] B. Moulton, M.J. Zaworotko, Chem. Rev. 101 (2001) 1629;
[b] O.R. Evans, W. Lin, Acc. Chem. Res. 35 (2002) 511.
[14] G.M. Sheldrick, SHELXS-97 Program for Crystal Structure Solution, University of
Göttingen, Göttingen, 1997.
[5] [a] C. Janiak, Dalton Trans. (2003) 2781;
[15] G.M. Sheldrick, SHELXL-97. Program for Crystal Structure Refinement,
University of Göttingen, Göttingen, 1997.
[b] S. Kitagawa, R. Kitaura, S.I. Noro, Angew. Chem. 116 (2004) 2388;
[c] M.P. Suh, Y.E. Cheon, E.Y. Lee, Coord. Chem. Rev. 252 (2008) 1007.
[6] [a] C.N.R. Rao, S. Natarajan, R. Vaidhyanathan, Angew. Chem. 116 (2004) 1490;
[b] N.W. Ockwig, O. Delgado-Friederichs, M. O’ Keeffee, O.M. Yaghi, Acc. Chem.
Res. 38 (2005) 176.
[16] L.Y. Zhang, J.P. Zhang, Y.Y. Lin, X.M. Chen, Cryst. Growth Des.
1684.
6 (2006)
[17] [a] J.L. Atwood, L.J. Barbour, T.J. Ness, C.L. Raston, P.L. Raston, J. Am. Chem. Soc.
123 (2001) 7192;
[7] [a] R. Sun, S. Wang, H. Xing, J. Bai, Y. Li, Y. Pan, X. You, Inorg. Chem. 46 (2007)
8451;
[b] L.F. Ma, L.Y. Wang, X.K. Huo, Y.Y. Wang, Y.T. Fan, J.G. Wang, S.H. Chen, Cryst.
Growth Des. 8 (2008) 620.
[b] M. Du, Z.H. Zhang, X.J. Zhao, Q. Xu, Inorg. Chem. 45 (2006) 5785.
[8] [a] S.A. Bourne, A. Mondal, M.J. Zaworotko, Cryst. Eng. 4 (2001) 25;
[b] S.A. Biyrne, J.J. Lu, A. Mondal, B. Moulton, M.J. Zaworotko, Angew. Chem.,
Int. Ed. Engl. 40 (2001) 2111;
[18] R.C. Binning, J.Y. Ishikawa, J. Phys. Chem. A 104 (2000) 8097.
[19] L.F. Ma, Y.Y. Wang, L.Y. Wang, J.Q. Liu, Y.P. Wu, J.G. Wang, Q.Z. Shi, S.M. Peng,
Eur. J. Inorg. Chem. (2008) 693.
[20] [a] K. Raghuraman, K.K. Katti, L.J. Barbour, N. Pillarsetty, C.L. Barnes, K.V. Katti,
J. Am. Chem. Soc. 125 (2003) 6955;
[c] L. Pan, N.W. Zheng, Y.G. Wu, S. Han, R.Y. Yang, X.Y. Huang, J. Li, Inorg. Chem.
40 (2001) 828;
[d] L. Pan, K.M. Adams, H.E. Hernandez, X.T. Wang, C. Zheng, Y. Hattori, K.
Kaneko, J. Am. Chem. Soc. 125 (2003) 3062;
[e] H. Abourahma, B. Moulton, V. Kravtsov, M.J. Zaworotko, J. Am. Chem. Soc.
124 (2002) 9990.
[b] Y. Liu, C. Liu, X.W. Ni, X.S. Luo, J. Lu, Z.H. Shen, Acta Photonica Sinica 26
(2006) 1580 (in Chinese);
[c] Y. Liu, C.D. Peng, X.W. Ni, J. Lu, Z.H. Shen, X.S. Luo, Acta Photonica Sinica 36
(2007) 1677.
[21] Y.F. Zhou, R.H. Wang, B.L. Wu, R. Cao, M.C. Hong, J. Mol. Struct. 697 (2004)
73.
[22] [a] X.L. Wang, C. Qin, E.B. Wang, Y.G. Li, Z.M. Su, L. Xu, L. Carlucci, Angew.
Chem. Int. Ed. 44 (2005) 5824;
[b] V.A. Batten, L. Carlucci, G. Ciani, D.M. Proserpio, CryEngComm. 6 (2004)
377.
[23] Y.Y. Liu, Y.Q. Huang, W. Shi, P. Cheng, D.Z. Liao, S.P. Yan, Cryst. Growth Des. 7
(2007) 1483.
[9] B.H. Ye, B.B. Ding, Y.Q. Weng, X.M. Chen, J. Am. Chem. Soc. 5 (2005) 801.
[10] [a] X. Lin, Y.Q. Wang, R. Cao, F. Li, W.H. Bi, Acta Cryst. 61 (2005) 292;
[b] M.A. Braverman, R.L. LaDuca, Cryst. Growth Des. 7 (2007) 2343.
[11] [a] X.M. Chen, G.F. Liu, Chem. Eur. 8 (2002) 4811;
[b] Y. Yang, M.H. Zeng, F.Y. Meng, X.J. Deng, H. Liang, S.H. Zhang, Chin. J. Inorg.
Chem. 23 (2007) 137.
[12] R.D. Bergougnant, A.Y. Robin, K.M. Fromm, Cryst. Growth Des. 5 (2005) 1691.
[13] G.M. Sheldrick, SADABS Program for Bruker Area Detector Absorption
Correction, University of Göttingen, Göttingen, 1997.
[24] X.L. Chen, J.J. Wang, H.M. Hu, F. Fu, H.M. Shu, M.L. Yang, G.L. Xue, C.Q. Du, Y.J.
Yao, Z. Anorg, Allg. Chem. 633 (2007) 2053.