Interlocked and interdigitated architectures from self-assembly of long flexible ligands and cadmium salts

Article abstract of DOI:10.1002/anie.200460758

Noninterpenetrating structures are formed by self-assembly of cadmium salts and long flexible ligands. In one case exceptional ninefold interlocked homochiral helices are built from achiral components (see picture). The helices are chemically independent but physically interwoven. This represents the highest degree of entanglement presently known for a noninterpenetrating system.

Full text of DOI:10.1002/anie.200460758

Communications
appealing interpenetrated nets, in which only internal con-
nections are broken to separate individual nets, have been
reported and reviewed by Batten and Robson.[3] In contrast,
other types of entangled architectures that have recently been
described—such as infinite multiple helices,[4] two-dimen-
sional clothlike warp-and-weft sheet structures,[5] interdigi-
tated structures in a gearlike (or tongue-and-groove) fash-
ion,[6] and polythreaded structures with poly-pseudo-rotax-
anes[7]—can, in principle, be disentangled without breaking
links. Moreover, these entangled nets can lead to synthetic
supramolecular arrays with potential applications in asym-
metric catalysis, drug-delivery vehicles, and sensor devices.
Unfortunately, these species are still rare, as evidenced in
a recent review by Ciani and co-workers,[8] and therefore the
exploration of new synthetic routes to this class of supra-
molecular architectures is one of the most challenging issues
in current synthetic chemistry. On the other hand, it is well-
known that product topology can often be controlled and
modulated by selecting the coordination geometry of the
metal ions and the chemical nature of the organic ligands.
Usually, long ligands will lead to larger voids that may result
in interpenetrated structures,[3] the most outstanding example
of which is 1,2-bis(4-pyridyl)ethane (bpe). With this ligand,
many beautiful interpenetrated networks of ingenious design
have been constructed, ranging from interpenetrating 1D
ladders to 3D nets.[9]
Self-assembly
However, these results do not mean that other types of
entangled structures cannot be formed in the presence of long
flexible ligands. If another configurational ligand is intro-
duced, it may be possible to gain noninterpenetrating nets by
combining different precursors. In this regard, for our
synthetic strategy we choose an analogy of bpe, biphenyle-
thene-4,4’-dicarboxylic acid (bpea), whose coordination
chemistry, to the best of our knowledge, has not been
previously investigated. Due to the replacement of two
pyridyl groups by aromatic carboxy groups, bpea will be
more flexible than bpe. Therefore, to avoid interpenetration
the heterocyclic aromatic ligand 1,10-phenanthroline (phen)
was introduced based on the following considerations: 1) The
steric hindrance at the metal center will be increased when the
bulky aromatic ligand binds to the metal ion; this reduces the
dimension of the net formed. Lower dimensional nets are
usually less likely to interpenetrate because there are more
possible ways to maximize the packing efficiency.[10] 2) Che-
lating bipyridyl-like ligands may provide recognition sites for
p–p stacking interactions to form interesting supramolecular
structures. 3) The conjugated p systems containing (hetero)-
aromatic rings are currently of interest in the development of
fluorescent materials and use as model compounds for
electroluminescence and optical switching devices.[11]
Interlocked and Interdigitated Architectures from
Self-Assembly of Long Flexible Ligands and
Cadmium Salts**
Xin-Long Wang, Chao Qin, En-Bo Wang,* Lin Xu,
Zhong-Min Su,* and Chang-Wen Hu
The current interest in the crystal engineering of coordination
polymer frameworks not only stems from their potential
applications in microelectronics, nonlinear optics, porous
materials, and catalysis, but also from their intriguing variety
of architectures and topologies.[1,2] Up to now, a variety of
[*] Dr. X.-L. Wang, Dr. C. Qin, Prof. E.-B. Wang, Prof. L. Xu, Prof. C.-W. Hu
Institute of Polyoxometalate Chemistry
Department of Chemistry
Northeast Normal University
Changchun 130024 (China)
Fax: (+86)431-5684009
E-mail: wangenbo@public.cc.jl.cn
Prof. Z.-M. Su
Institute of Functional Materials
Department of Chemistry
Northeast Normal University
Changchun, Jilin, 130024 (China)
Fax: (+86)431-5684009
Due to the low solubility of the ligands, we adopted
hydrothermal techniques and successfully synthesized three
noninterpenetrating species. The first complex [Cd(bpea)-
(phen)2] (1) exhibits a remarkable assembly of ninefold
interlocked homochiral helices that are built from achiral
components. [Cd2(bpea)(pt)(phen)2][Cd(pt)(phen)]·2H2O (2,
pt = phthalate) contains neutral 2D puckered sheets that are
interdigitated by neutral 1D zigzag chains. The final com-
pound [Cd3(bpea)(phen)3(OH)3(H2O)]·0.5bpea·4H2O (3)
E-mail: zmsu@nenu.edu.cn
[**] This work was financially supported by the National Natural Science
Foundation of China (No. 20371011).
Supporting information for this article is available on the WWW
under http://www.angewandte.org or fromthe author.
5036
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/anie.200460758
Angew. Chem. Int. Ed. 2004, 43, 5036 –5040

Angewandte
Chemie
has unprecedented hexanuclear cadmium clusters that show a
3D supramolecular host–guest network.
X-ray crystallography[12] shows that 1 has a 3D chiral
framework assembled by nine interlocking nanotubes. Com-
plex 1 crystallizes in the chiral space group P4(3), with one Cd
atom, one bpea ligand, and two phen ligands in the
asymmetric unit. The Cd center is coordinated by four
À
nitrogen atoms from two chelating phen ligands (mean Cd
N 2.477(3) Š) and two oxygen atoms from two monodentate
À
carboxylate ends of two bpea ligands (mean Cd O
2.259(3) Š) to furnish a distorted octahedral geometry. The
[Cd(phen)2]2+ molecular corners are bridged by long linear
spacers to form an infinite helical chain running along the c
axis (Figure 1a). The left-handed helix is generated around
Figure 2. A schematic illustration of the ninefold interlocked homochi-
ral helices of 1.
penetrated network, the individual chains can “ideally” be
separated without breaking links.
For typical interpenetrating systems, the world record is
held by a tenfold interpenetrated diamondoid net exclusively
based on coordinative bonds.[13] Among the new structures
showing entanglement, a rather remarkable example was
reported by Lin and co-workers in which the 3D chiral
framework results from the assembly of quintuple interwoven
helices built from axially chiral bityridines.[14] Therefore, to
our knowledge, the ninefold interlocking homochiral helices
constructed from achiral components in 1 represents the
highest degree of entanglement known in a noninterpene-
trating system.
Figure 1. Crystal structure of 1. a) View of the left-handed 41 helical
chain. b) Schematic view of the helical chain. c) Perspective view of a
chiral nanotube with an opening of about 1.8”1.8 nm.
The structure determination of 2 shows the presence of
two crystallographically independent polymer motifs in the
same crystal. One motif is a 1D zigzag chain constructed from
mononuclear Cd atoms, pt, and phen (Figure 3a). The Cd
center has a distorted octahedral coordination environment
containing two nitrogen atoms of a chelating phen ligand
the crystallographic 41 axis with a pitch of 24.46 Š. Notably,
each pair of nearly perpendicular phen ligands bonded to the
Cd atom point away from the helical axis; this steric
orientation leads to the generation of a tetragonal nanotube
with an opening of about 1.8 ” 1.8 nm (Figure 1b,c).
À
(Cd N 2.278(5) Š) and four oxygen atoms of two chelating
À
carboxylate ends of two pt ligands (Cd O 2.332(5) Š).
The most fascinating structural feature of 1 is that each
helical chain is chemically independent but physically inter-
woven with the same independent chains in all directions,
whose unique entangled fashion can be described stepwise.
First of all, four identical helices interweave the central one
along the a and b axes with an extent of intercalation of about
0.72 nm. Another four helices further interlock the central
one along the [a,b], [Àa,Àb], [a,Àb], and [Àa,b] directions
with an extent of intercalation of about 0.24 nm. Thus, each
helical chain is interlocked by eight equivalent polymeric
units to give a periodically ordered interlocked architecture
(Figure 2). The resulting 3D chiral network can therefore be
described as an infinite interlocked array originating from
ninefold interwoven homochiral helices. The framework is
stabilized by strong p–p stacking interactions between the
interwoven aryl groups: Parallel stacking with face-to-face
distances of 3.350 Š between phen ligands and 3.400 Š
between phen and bpea ligands. In contrast to the inter-
The dangling phen groups are perpendicular to the propaga-
tion direction of the chain and bristle out in opposite
directions. This arrangement paves the way for interdigita-
tion.
The other polymer motif of 2 is a 2D puckered sheet of
(4,4) topology built up from dinuclear Cd units with three
types of ligands, that is, pt, bpea, and phen (Figure 3b).
Although a few polymer frames with two kinds of aromatic
ligands have been reported,[15] there are no examples in which
more than two different aromatic ligands are incorporated
into a metal–organic polymer network. In contrast to the Cd
atom in the first motif, the Cd center in the second motif
adopts a seven-coordinate geometry made up of two nitrogen
À
atom of a chelating phen ligand (Cd N 2.351(5) Š) and five
oxygen atoms from one chelating bpea and two pt ligands
À
(Cd O 2.425(4) Š). Two crystallographically equivalent Cd
atoms are bridged by two m3-oxygen atoms to generate a
dinuclear unit [Cd···Cd(A) 3.693(9) Š]. Four such dinuclear
Angew. Chem. Int. Ed. 2004, 43, 5036 –5040
www.angewandte.org
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
5037

Communications
Figure 4. Crystal structure of 3. a) View of the ladderlike hexanuclear
cadmium cluster. b) View of the 1D ladder highlighting the hexanuclear
metal clusters as rungs. c) View of the supramolecular host–guest net-
work in which the location of the guest bpea2À ions in the parallelo-
gramchannels is created by stacking of the ladders.
Figure 3. Crystal structure of 2. a) View of the zigzag chain. b) View of
the puckered sheet. c) View of the entanglement of the 1D chains and
2D sheets in the ABAB mode. The interdigitation of the phen groups is
clearly visible.
units are alternately linked by pt and bpea ligands to form a
long and narrow window, which provides a snug habitat for
dangling phen groups of the 1D chain.
cadmium clusters in which three crystallographically inde-
pendent cadmium(ii) atoms exhibit three different coordina-
tion environments. In addition to a chelating phen ligand, Cd1
is coordinated by a monodentate bpea ligand and three m3-
OH groups, Cd2 is coordinated by one aqua ligand and three
m3-OH groups, and Cd3 is coordinated by a chelating bpea
ligand and two m3-OH groups. Each m3-OH group interlinks
three Cd atoms in a trigonal shape (Cd···Cd 3.511(6)–
3.909(7) Š) to give an edge-sharing hexanuclear cadmium
cluster. While a few [Cd3(m3-OH)]5+ cores[17] and octanuclear
cadmium clusters[18] have been reported, such a hexanuclear
ladderlike metal core featuring cadmium–hydroxy clusters
has never been shown before. Neighboring hexanuclear
cadmium clusters are linked by two linear bpea spacers,
The unexpected aspect of 2 is how structurally divergent
the two motifs are rationally combined together. The width of
a window within a puckered sheet, dictated by the shortest
carbon–carbon separation between two opposite bpea
ligands, is about 8.80 Š, while the period of a zigzag chain is
about 17.56 Š. This allows every other window of a sheet to
be penetrated by one side of the phen groups of the 1D chains
above the layer. The remaining windows are penetrated in the
same way by the phen groups below the layer. Thus, each
sheet is simultaneously interdigitated by chains located above
and below. The two different structural motifs alternate in the
crystals, stacking with a sequence ABAB to form a beautiful thus producing a new type of pseudo-molecular ladder in
3D array (Figure 3c).
which the hexanuclear cadmium clusters act as inner rungs
(Figure 4b). The phen ligands are orientated away from the
ladder and play an important role in subsequent packing into
a three-dimensional network.
The coexistence of different structural motifs in the same
crystal is rather rare.[16] Among the few examples of
interdigitation—almost all with identical motifs, generally a
2D sheet[6a–d]—only one involves two different polymer
motifs, namely, [Zn2.5(L)(m3-OH)](H2O)5 (L = 3-{[4-(4-pyri-
dylethenyl)phenyl]ethenyl}benzoate).[6e] In this structure the
1D and 2D motifs are both constructed from the L ligand.
Therefore, compound 2, in which the 1D and 2D motifs are
constructed from different components (1D: pt and phen; 2D:
pt, phen, and bpea) represents a new example of interdigi-
tation: there has now been a progression from one motif with
a single ligand, to different motifs with a single ligand, to
finally different motifs with diverse ligands.
Interestingly, adjacent ladders in 3 are interdigitated in a
À
zipper fashion to form 2D layers with significant C H···p
interactions between the aromatic rings of different ladders;
the edge-to-face separation is about 3.70 Š. These layers are
further packed into a 3D network featuring 1D parallelo-
gram-shaped cationic channels (8.91 ” 9.97 Š) under the
direction of strong p–p stacking interactions between the
phen groups; the face-to-face distance is about 3.414 Š.
Completely deprotonated bpea guests reside in the channels
and are hydrogen-bonded to the aqua ligands of the ladders
(O···O 2.659(9) Š, Figure 4c. Therefore, the architecture of 3
can be best described as a 3D supramolecular host–guest
network.
The structure of 3 consists of positive 1D pseudo-
molecular ladders and negative bpea2À ions. As shown in
Figure 4a, the 1D ladder contains unprecedented hexanuclear
5038
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
Angew. Chem. Int. Ed. 2004, 43, 5036 –5040

Angewandte
Chemie
Compounds 1–3 have much in common: All are
Cd(bpea)(phen) derivatives and contain 1D chain motifs in
their crystal structures. This could be related to the fact that
chelating ligands such as phen serve a “passive” role by
occupying coordination sites on the metal centers and
represent another important branch in the realm of entangle-
ment and open interesting perspectives in the study of these
materials.
providing steric constrains, thus preventing spatial extension Experimental Section
1:
A mixture of Cd(NO3)2·4H2O (154 mg, 0.5 mmol), H2bpea
of the skeleton to higher dimensions. Similar behavior has
been observed before.[19] Despite the similarities among 1–3,
the three types of chains (helical, zigzag, and ladderlike) fulfill
different functions in crystal packing. Although some possible
factors have been discussed here, we are unable to propose
definite reasons as to why each compound adopts a different
strategy.
(134 mg, 0.5 mmol), phen (198 mg, 1 mmol), and water (10 mL) was
placed in a 23-ml Teflon reactor and kept under autogenous pressure
at 1408C for 5 d. Then the mixture was cooled to room temperature at
a rate of 108ChÀ1, and colorless crystals of 1 were obtained (yield:
192 mg, 52% based on Cd). C,H,N analysis calcd (%) for
C40H26CdN4O4: C 65.00, H 3.55, N 7.58; found: C 64.65, H 3.27, N,
7.81.
To examine the contribution of d10 metal polynuclear
clusters to the photoluminescent properties of these systems,
the luminescence of 3 was investigated. While the free H2bpea
ligand displays weak luminescence in the solid state at room
temperature (see Figure S1 in the Supporting Information),
compound 3 exhibits an intense blue radiation emission
maximum at l ꢀ 489 nm upon excitation at l = 386 nm
(Figure 5). The enhancement of luminescence may be attrib-
2: A mixture of Cd(NO3)2·4H2O (460 mg, 1.5 mmol), H2bpea
(134 mg, 0.5 mmol), phen (300 mg, 1.5 mmol), H2pt (250 mg,
1.5 mmol), and water (10 mL) was placed in a 23-ml Teflon reactor
and kept under autogenous pressure at 1608C for 5 d. Then the
mixture was cooled to room temperature at a rate of 108ChÀ1, and
light-yellow crystals of 2 were obtained (yield: 140 mg, 56% based on
Cd). C,H,N analysis calcd (%) for C68H46Cd3N6O14: C 54.10, H 3.07, N
5.57; found: C 53.84, H 2.77, N, 5.75.
3: A mixture of Cd(NO3)2·4H2O (308 mg, 1 mmol), H2bpea
(134 mg, 0.5 mmol), phen (300 mg, 1.5 mmol), and water (10 mL) was
placed in a 23-ml Teflon reactor and kept under autogenous pressure
at 1808C for 3 d. Then the mixture was cooled to room temperature at
a rate of 108ChÀ1, and colorless crystals of 3 were obtained (yield:
302 mg, 64% based on Cd). C,H,N analysis calcd (%) for
C60H52Cd3N6O14: C 50.80, H 3.70, N 5.93; found: C 50.45, H 3.44, N,
6.38.
Received: May 24, 2004
Keywords: cadmium · hydrothermal synthesis · luminescence ·
.
polymers · supramolecular chemistry
[1] Reviews: a) P. J. Hagrman, D. Hagrman, J. Zubieta, Angew.
Chem. 1999, 111, 2798; Angew. Chem. Int. Ed. 1999, 38, 2638;
b) A. J. Blake, N. R. Champness, P. Hubberstey, W. S. Li, M. A.
Withersby, M. Schröder, Coord. Chem. Rev. 1999, 183, 117; c) B.
Moulton, M. J. Zaworotko, Chem. Rev. 2001, 101, 1629; d) O. R.
Evans, W. Lin, Acc. Chem. Res. 2002, 35, 511; e) O. M. Yaghi, M.
OꢀKeeffe, N. W. Ockwig, H. K. Chae, M. Eddaoudi, J. Kim,
Nature 2003, 423, 705; f) A. Müller, S. K. Das, S. Talismanov, S.
Roy, E. Beckmann, H. Bögge, M. Schmidtmann, A. Merca, A.
Berkle, L. Allouche, Y. Zhou, L. Zhang, Angew. Chem. 2003,
115, 5193; Angew. Chem. Int. Ed. 2003, 42, 5039; g) C. N. R. Rao,
S. Natarajan, R. Vaidhyanathan, Angew. Chem. 2004, 116, 1490;
Angew. Chem. Int. Ed. 2004, 43, 1466; h) S. Kitagawa, R.
Kitaura, S. I. Noro, Angew. Chem. 2004, 116, 2388; Angew.
Chem. Int. Ed. 2004, 43, 2334.
[2] For recent examples, see a) E. Lee, J. Heo, K. Kim, Angew.
Chem. 2000, 112, 2811; Angew. Chem. Int. Ed. 2000, 39, 2699;
b) G. J. Halder, C. J. Kepert, B. Moubaraki, K. S. Murry, J. D.
Cashion, Science 2002, 298, 1762; c) T. J. Prior, D. Bradshaw, S. J.
Teat, M. J. Rosseinsky, Chem. Commun. 2003, 500; d) A. Galet,
M. C. Munoz, J. A. Real, J. Am. Chem. Soc. 2003, 125, 14224;
e) B. Q. Ma, H. L. Sun, S. Gao,Chem. Commun. 2003, 2164; f) L.
Pan, H. Liu, X. Lei, X. Huang, D. H. Olson, N. J. Turro, J. Li,
Angew. Chem. 2003, 115, 560; Angew. Chem. Int. Ed. 2003, 42,
542; g) X. L. Wang, C. Qin, E. B. Wang, Y. G. Li, C. W. Hu, L.
Xu, Chem. Commun. 2004, 378; h) X. H. Bu, M. L. Tong, H. C.
Chang, S. Kitagawa, S. R. Batten, Angew. Chem. 2004, 116, 194;
Angew. Chem. Int. Ed. 2004, 43, 192.
Figure 5. Photoluminescent spectra of 3 in the solid state at room
temperature. Ex=excitation, Em=emission.
uted to ligand chelation to the metal center, which effectively
increases the rigidity of the ligand and reduces the loss of
energy by radiationless decay.[20] As with other metal–
hydroxy clusters,[18b,21] the lifetime of 3 is about 14 ns, which
is significantly longer than for systems without metal–hydroxy
clusters. This fact may be ascribed to the presence of the metal
clusters, since the m3-OH ligand may tighten the whole
skeleton, resulting in much weaker vibrations.
In conclusion, we have presented a rational synthetic
strategy that successfully provided three coordination poly-
mers by combining a long flexible ligand and a bulky
heterocyclic aromatic ligand, which show different packing
modes. Although the final polymeric architectures are
impossible to predict with our present state of knowledge,
the strategy represents a potential approach for the design of
noninterpenetrating structures with long flexible ligands. In
addition to the well-known interpenetrated frameworks,
these new types of supramolecular entangled networks
Angew. Chem. Int. Ed. 2004, 43, 5036 –5040
www.angewandte.org
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
5039

Communications
[3] S. R. Batten, R. Robson, Angew. Chem. 1998, 110, 1558; Angew.
[17] a) W. Lin, Z. Wang, L. Ma, J. Am. Chem. Soc. 1999, 121, 11249;
b) X. Xue, X. S. Wang, L. Z. Wang, R. G. Xiong, B. F. Abrahams,
X. Z. You, Z. L. Xue, C. M. Che, Inorg. Chem. 2002, 41, 6544.
[18] a) R. W. Saalfrank, N. Löw, S. Trummer, G. M. Sheldrick, M.
Teichert, D. Stalke. Eur. J. Inorg. Chem. 1998, 559; b) S. L.
Zheng, J. H. Yang, X. L. Yu, X. M. Chen, W. T. Wong, Inorg.
Chem. 2004, 43, 830.
[19] P. J. Hagrman, J. Zubieta, Inorg. Chem. 2000, 39, 5218.
[20] a) Photochemistry and Photophysics of Coordination Com-
pounds (Eds.: H. Yersin, A. Vogler), Springer, Berlin, 1987;
b) B. Valeur, Molecular Fluorescence: Principles and Applica-
tion, Wiley-VCH, Weinheim, 2002.
Chem. Int. Ed. 1998, 37, 1460.
[4] a) S. Sailaja, M. V. Rajasekharan, Inorg. Chem. 2000, 39, 4586;
b) P. Grosshans, A. Jouaiti, V. Bulach, J. M. Planeix, M. W.
Hosseini, J. F. Nicoud, Chem. Commun. 2003, 1336; c) Y. Cui,
H. L. Ngo, W. Lin, Chem. Commun. 2003, 1388.
[5] a) P. M. Van Calcar, M. M. Olmstead, A. L. Balch, Inorg. Chem.
1997, 36, 5231; b) L. Carlucci, G. Ciani, A. Gramaccioli, D. M.
Proserpio, S. Rizzato, CrystEngComm 2000, 29; c) I. Ino, J. C.
Zhong, M. Munakata, T. Kuroda-Sowa, M. Maekawa, Y.
Suenaga, Y. Kitamori, Inorg. Chem. 2000, 39, 4273; d) Y. H. Li,
C. Y. Su, A. M. Goforth, K. D. Shimizu, K. D. Gray, M. D. Smith,
H. C. zur Loye, Chem. Commun. 2003, 1630.
[6] a) M. Kondo, T. Joshitomi, K. Seki, H. Matsuzaka, S. Kitagawa,
Angew. Chem. 1997, 109, 1844; Angew. Chem. Int. Ed. Engl.
1997, 36, 1725; b) K. N. Power, T. L. Hennigar, M. J. Zaworotko,
New J. Chem. 1998, 177; c) L. Carlucci, G. Ciani, P. Macchi, D. M.
Proserpio, S. Rizzato, Chem. Eur. J. 1999, 5, 237; d) S. R. Batten,
B. F. Hoskins, R. Robson, Chem. Eur. J. 2000, 6, 156; e) P.
Ayyappa, O. R. Evans, W. Lin, Inorg. Chem. 2002, 41, 3328.
[7] a) C. V. K. Sharma, R. D. Rogers, Chem. Commun. 1999, 83;
b) L. Carlucci, G. Ciani, D. M. Proserpio, Chem. Commun. 1999,
449; c) K. Biradha, M. Fujita, Chem. Commun. 2002, 1866.
[8] L. Carlucci, G. Ciani, D. M. Proserpio, Coord. Chem. Rev. 2003,
246, 247.
[21] a) H. Kunkey, A. Vogler, J. Chem. Soc. Chem. Commun. 1990,
1204; b) S. L. Zheng, J. P. Zhang, X. M. Chen, Z. L. Huang, Z. Y.
Lin, W. T. Wong, Chem. Eur. J. 2003, 9, 3888.
[9] For example, see a) Y. B. Dong, R. C. Layland, N. G. Pschirer,
M. D. Smith, U. H. F. Bunz, H. C. zur Loye, Chem. Mater. 1999,
11, 1413; b) L. Carlucci, G. Ciani, D. M. Proserpio, S. Rizzato,
CrystEngComm 2003, 5, 190; c) J. Luo, M. Hong, R. Wang, R.
Cao, L. Han, Z. Lin, Eur. J. Inorg. Chem. 2003, 2705.
[10] S. R. Batten, B. F. Hoskins, B. Moubaraki, K. S. Murray, R.
Robson, Chem. Commun. 2000, 1095.
[11] U. W. Grummt, E. Birckner, E. Klemm, D. A. M. Egbe, B. Heise,
J. Phys. Org. Chem. 2000, 13, 112.
[12] Crystal data for 1 (C40H26CdN4O4): Mr = 739.05, tetragonal,
space group P4(3), a = b = 11.1568(16), c = 24.461(5) Š, V=
3044.7(9) Š3, Z = 4, 1calcd = 1.612 mgmÀ3, Flack parameter=
0.028(16), final R1 = 0.0267 for 6819 independent reflections
[I > 2s(I)]. Crystal data for 2 (C68H46Cd3N6O14): Mr = 1508.31,
monoclinic, space group P2/c, a = 16.776(3), b = 10.141(2), c =
17.559(4) Š, b = 97.11(3)8, V= 2964.2(10) Š3, Z = 2, 1calcd
=
1.690 mgmÀ3, final R1 = 0.0670 for 6666 independent reflections
[I > 2s(I)]. Crystal data for 3 (C60H52Cd3N6O14): Mr = 1418.28,
¯
triclinic, space group P1, a = 13.214(3), b = 13.661(3), c =
16.964(3) Š, a = 113.03(3), b = 92.53(3), c = 90.27(3)8, V=
2814.6(10) Š3, Z = 2, 1calcd = 1.673 mgmÀ3, final R1 = 0.0613 for
12603 independent reflections [I > 2s(I)]. The data were
collected at 298(2) K on a Rigaku R-AXIS RAPID IP diffrac-
tometer with MoKa monochromated radiation (l = 0.71073 Š).
The structures were solved by direct methods using SHELXS-97
and refined using Fourier techniques. CCDC 239159–239161
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge via www.ccdc.cam.a-
c.uk/conts/retrieving.html (or from the Cambridge Crystallo-
graphic Data Centre, 12, Union Road, Cambridge CB21EZ,
UK; fax: (+ 44)1223-336-033; or deposit@ccdc.cam.ac.uk).
[13] L. Carlucci, G. Ciani, D. M. Proserpio, S. Rizzato, Chem. Eur. J.
2002, 8, 1519.
[14] Y. Cui, S. J. Lee, W. Lin, J. Am. Chem. Soc. 2003, 125, 6014.
[15] a) W. Chen, J. Y. Wang, C. Chen, Q. Yue, H. M. Yuan, J. S. Chen,
S. N. Wang, Inorg. Chem. 2003, 42, 944; b) X. M. Chen, G. F. Liu,
Chem. Eur. J. 2002, 8, 4811.
[16] For example, see a) S. R. Batten, CrystEngComm 2001, 18;
b) D. M. Ciurtin, M. D. Smith, H. C. zur Loye, Chem. Commun.
2002, 74; L. Carlucci, G. Ciani, D. M. Proserpio, Chem.
Commun. 2004, 380.
5040
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
Angew. Chem. Int. Ed. 2004, 43, 5036 –5040