Carbon Dioxide Fixation and Sulfate Sequestration by a Supramolecular Trigonal Bipyramid

Article abstract of DOI:10.1002/anie.201504856

The subcomponent self-assembly of a bent dialdehyde ligand and different cationic and anionic templates led to the formation of two new metallosupramolecular architectures: a Fe^II₄L₆molecular rectangle was isolated following reaction of the ligand with iron(II) tetrafluoroborate, and a M₅L₆trigonal bipyramidal structure was constructed from either zinc(II) tetrafluoroborate or cadmium(II) trifluoromethanesulfonate. The spatially constrained arrangement of the three equatorial metal ions in the M₅L₆structures was found to induce small-molecule transformations. Atmospheric carbon dioxide was fixed as carbonate and bound to the equatorial metal centers in both the Zn₅L₆and Cd₅L₆assemblies, and sulfur dioxide was hydrated and bound as the sulfite dianion in the Zn₅L₆structure. Subsequent in situ oxidation of the sulfite dianion resulted in a sulfate dianion bound within the supramolecular pocket.

Full text of DOI:10.1002/anie.201504856

.
Angewandte
Communications
International Edition: DOI: 10.1002/anie.201504856
German Edition: DOI: 10.1002/ange.201504856
Supramolecular Chemistry
Carbon Dioxide Fixation and Sulfate Sequestration by a Supra-
molecular Trigonal Bipyramid
Colm Browne, William J. Ramsay, Tanya K. Ronson, John Medley-Hallam, and
Jonathan R. Nitschke*
[
12]
Abstract: The subcomponent self-assembly of a bent di-
aldehyde ligand and different cationic and anionic templates
led to the formation of two new metallosupramolecular archi-
solvent,
have been shown to be important not only in
governing the overall structures formed, but also for defining
the physicochemical characteristics of the resulting cavities.
Rules have been established to define the geometric
parameters that lead to the formation of metal–organic
II
tectures: a Fe L molecular rectangle was isolated following
4
6
reaction of the ligand with iron(II) tetrafluoroborate, and
a M L trigonal bipyramidal structure was constructed from
[
13]
[14]
tetrahedral
or cubic
assemblies, and rational design
5
6
either zinc(II) tetrafluoroborate or cadmium(II) trifluoro-
methanesulfonate. The spatially constrained arrangement of
the three equatorial metal ions in the M L structures was
principles have been put forth to describe the preparation
[9a,15]
of more complex three-dimensional architectures.
Based
upon the understanding gained as these rule sets were
deciphered, ligand geometries may be identified wherein
the rules do not suggest a clearly defined self-assembly
outcome. The design of a rigid ligand that fits one of these
5
6
found to induce small-molecule transformations. Atmospheric
carbon dioxide was fixed as carbonate and bound to the
equatorial metal centers in both the Zn L6 and Cd L6
5
5
[16]
assemblies, and sulfur dioxide was hydrated and bound as
the sulfite dianion in the Zn L structure. Subsequent in situ
geometries may thus allow for serendipity to be engineered
and for new functions to be accessed that are difficult to
envisage using rationally designed structures.
5
6
oxidation of the sulfite dianion resulted in a sulfate dianion
bound within the supramolecular pocket.
Subcomponent A (Scheme 1) was prepared in this spirit,
as described in the Supporting Information (Section S1.2).
The coordination vectors of A converge in such a way as to
T
hree-dimensional metal–organic self-assembly allows for
[17]
the preparation of increasingly intricate structures that
disfavor the formation of a tetrahedron, cube, or polymer,
[
1]
contain void spaces. Valuable understanding is being
gained as to how to design and control the chemical environ-
ments of these voids, allowing the inner phases of new
assemblies to display properties distinct from the solvent
environment and enabling selective recognition and trans-
[
2]
formations of various substrates.
The combination of multidentate coordinating ligands
and metal ions with well-defined coordination spheres, in
[
3]
conjunction with secondary templates such as anions, has
proven to be a powerful construction technique for supra-
[
4]
molecular assembly. The arrangement of the ligands around
these templates can generate isolated cavities which have
[5]
found diverse applications, including in catalysis, gas
[
6]
[7]
[8]
storage, and selective guest binding, among others.
Minor and subtle variations in ligand design, such as the
[
9]
ligand bend angle, preferred metal coordination geometry
and stoichiometry, flexibility, and interactions with the
[
10]
[11]
[
$] [+]
[+]
[
*] Dr. C. Browne,
W. J. Ramsay, Dr. T. K. Ronson, J. Medley-Hallam,
Prof. J. R. Nitschke
University of Cambridge, Department of Chemistry
Lensfield Road, Cambridge, CB2 1EW (UK)
E-mail: jrn34@cam.ac.uk
Homepage: http://www-jrn.ch.cam.ac.uk/
$
[
] Current address:
Scheme 1. The self-assembly of dialdehyde A with p-anisidine and
School of Chemistry, University of Manchester
Oxford Road, Manchester, M13 9PL (UK)
II
II
i) M(NTf ) (M=Fe , Zn ) in acetonitrile led to the formation of
2
2
helicates 1 and 2, respectively. When ii) Fe(BF ) , iii) Zn(BF ) , or
4
2
4 2
+
[
] These authors contributed equally to this work.
iv) Cd(OTf) were employed in the self-assembly procedure, the anions
2
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201504856.
and metal cations cooperatively templated the structures of 3, 4 and 5,
respectively.
1
1122
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Angewandte
Chemie
and to destabilize a helicate. A instead generated a new class
of trigonal bipyramidal structures in which a central guest is
exposed directly to three dicationic metal centers, allowing
for selective transformations and substrate stabilization. A
was also found to generate a new M L molecular rectangle
of two intertwined ligands, forming a double-stranded helix.
Each helix within the rectangle bridges two metal centers with
identical handedness, with each helical edge mirroring the
otherꢀs handedness (Figure 1a). All metal centers have mer
coordination geometry, in contrast to the fac geometry usually
4
6
[23]
with different templates.
found in M L tetrahedra. The arrangement of the ligands
4 6
The reaction of iron(II) bis(trifluoromethanesulfonimide)
defines a binding pocket at each of the shorter rectangular
À
À
(
triflimide, NTf ) or zinc(II) triflimide (2 equiv) with p-
edges, each of which binds a BF4 ion (Figure 1b); the
2
À
anisidine (6 equiv) and A (3 equiv) in acetonitrile produced
M L helicate structures 1 or 2, respectively, as confirmed
distances between the protons of the ligand and the BF4 ions
(2.24–2.63 Š) are within the expected range for CH···F
2
3
[24]
19
by NMR spectroscopy and mass spectrometry (Scheme 1;
Sections S1.3 and S1.4). Triflimide is known to exercise less
influence as a template upon self-assembled metal–organic
hydrogen bonds.
Resonances in the F NMR spectrum
suggested that this interaction also existed in solution, in fast
exchange on the NMR timescale (Figure S10). We attribute
the stability of 3 to a combination of anion templation and
[
18]
[19]
structures than smaller noncoordinating anions, prompt-
À
[3c,25]
ing the investigation of tetrafluoroborate (BF ) as an anionic
aromatic stacking.
4
[
20]
template in place of triflimide in the system described in
Scheme 1.
Prompted by the novel structure of 3 templated by the
À
BF4 ion, we investigated the reaction of A, p-anisidine, and
Although the reaction between A (3 equiv), p-anisidine
Zn(BF ) in a 3:6:2 ratio in acetonitrile (Section S1.6). The
H NMR spectrum of the reaction mixture was again more
4
2
1
(
6 equiv), and Fe(BF ) (2 equiv) in acetonitrile produced
4
2
a deep-blue solution consistent with the formation of 1, the
H NMR spectrum of this solution was complex (Supporting
complex than that detected for helicate 2, and signals
corresponding to excess ligand were detected (Figure S13A).
However, DOSY NMR of the purified product gave results
consistent with the formation of a single species (Figure S14).
Single-crystal X-ray analysis revealed the presence of an
1
Information Figure S6), indicating the formation of a species
having lower than expected symmetry. Two distinguishable
products were evident by DOSY NMR experiments (Fig-
ure S7), with the chemical shifts of the signals for the
hydrodynamically smaller species consistent with those of
[26]
unusual Zn L trigonal bipyramid 4 (Figure 2).
5
6
II
The structure of 4 contains two Zn ions of identical
handedness and fac stereochemistry at the two apical vertices
(both enantiomers are present in the unit cell) and three
1
detected when Fe(NTf ) had been used. Signals attribut-
2 2
able to helicate 1 were detected by electrospray MS (Fig-
ure S8), and the second species was identified as having
a metal:ligand ratio of 4:6 (confirmed by HRMS, Figure S9),
suggesting the formation of a Fe L structure.
II
Zn ions in equatorial positions. The Zn L framework
5
6
displays approximate D symmetry but the crystal structure
3
of 4 is C symmetric because of the coordination environ-
4
6
[
1
21]
Single-crystal X-ray diffraction revealed the structure
ments of the equatorial metal centers. The Zn···Zn distance
II
of this Fe L species 3 (Figure 1). Instead of the tetrahedral
4
6
[22]
arrangement usually observed for M L assemblies, 3 has
4
6
II
four Fe centers arranged into a rectangle. The shorter edges
have an average Fe···Fe distance of 11.3 Š and are composed
of a single ligand that bridges two metal centers. The longer
edges have an average Fe···Fe distance of 13.4 Š and consist
Figure 1. a) Framework representation of the X-ray crystal structure of
À
3
, where the 2BF4 ions occupying the binding pockets are shown as
II
a space-filling model. Dark purple spheres correspond to Fe ions of D
stereochemistry, and light purple to L-Fe . The edges of the rectangle
II
Figure 2. a) Framework representation of the X-ray crystal structure of
À
are highlighted by yellow lines. b) Space-filling representation of 3,
highlighting the tight arrangement of the ligands around the BF4
ions. Atom colors: C=gray, N=blue, Fe =purple, H=white, F=cyan,
B=pink, O=red. Disorder, non-encapsulated anions, and solvent
molecules are omitted for clarity.
4, where the BF4 and hydroxide ions occupying the cavity are shown
À
in space-filling mode. b) The space-filling representation of 4 highlights
the aromatic stacking of the ligands. Atom colors: C=gray, N=blue,
Zn=yellow, H=white, F=cyan, B=pink, O=red. Disorder, non-
encapsulated anions, and solvent molecules are omitted for clarity.
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Angewandte
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between apical sites is 21.2 Š, and the Zn···Zn distances at the
equatorial positions range from 5.07 to 5.18 Š. The ligands
forming the edges of the trigonal bipyramid exhibit extensive
face-to-face aromatic stacking (Figure 2b), defining two
separate cavities that are separated by the equatorial ring of
The distance between the apical Cd centers in 5 is 21.9 Š,
with 4.74–5.06 Š between the equatorial centers, resulting in
a longer and narrower trigonal bipyramid in comparison to 4.
À
One of the encapsulated OTf ions shows CH···F and
[29]
CH···O interactions, which likely contribute both to guest
binding and host stability. The second cavity is also occupied
II
À
Zn centers. A BF4 ion is bound in each binding pocket,
stabilized by attractive electrostatic forces and CH···F hydro-
gen-bonding interactions with the protons lining the interior
À
by a OTf ion, which is bound as a tris(monodentate) ligand
II
bridging between the three equatorial Cd centers through its
19
of the binding pocket. An analysis of the F NMR spectrum
oxygen atoms (Figure 3b). Intriguingly, the octahedral coor-
À
II
revealed that the bound BF4 ions were in slow exchange on
dination sphere of the equatorial Cd centers is satisfied by
the NMR timescale in solution (Figure S15), with correlations
a carbonate dianion, which forms three bonds to the
equatorial metal centers with its oxygen atoms (Figure 3c).
19
1
to inward-facing host protons detected in the F– H HOESY
À
spectrum (Figure S16). A third BF4 ion is bound at the
The CÀO bond lengths of 1.26(1)–1.30(1) Š are in good
[
27]
[30]
equator of 4 and acts as a tris(monodentate) ligand,
agreement for those expected for carbonate.
The poor
II
bridging the three equatorial Zn centers with three of its
fluorine atoms. Two of these Zn ions are each coordinated to
solubility of the crystals of 5 hindered NMR characterization
and the investigation of carbonate binding in solution, but
signals detected in the mass spectrum of 5 were consistent
with carbonate binding in solution (Figure S21). As no
carbonate was added to the solution during the self-assembly
of 5, we infer that the anion was generated from atmospheric
II
an additional hydroxide ion; the equatorial belt thus consists
II
of two six-coordinate Zn centers and one five-coordinate
II
Zn ion. Several combinations of water, hydroxide, and
acetonitrile adducts were detected in the HRMS spectrum
after dissolving the crystals of 4 in acetonitrile (Figure S19),
suggesting dynamic exchange of these weakly bound ligands
at the equatorial positions in solution. This is consistent with
[31]
carbon dioxide; if self-assembly occurred under a nitrogen
atmosphere, 5 was not observed to form.
To better understand the carbonate binding abilities of
this new trigonal-bipyramidal structure type, further studies
focused upon the structurally similar compound 4 because of
the better solubility of this structure (Section S3.1).
When 4 self-assembled from its subcomponents under
a N2 atmosphere, ESI-MS identified the presence of the
trigonal bipyramid but extended heating did not yield any
changes (Figure S22). However, when this sample was
exposed to air and heated at 708C for an additional 48 h,
new signals corresponding to a carbonate adduct of 4 were
detected by mass spectrometry (Figures S22, S23). This
1
the multiple environments evident in the complex H NMR
spectrum of 4, with different signal intensities reflecting slight
preferences for the formation of some adducts over others.
II
As a result of the similar geometric preferences of Cd
II
[28]
and Zn ions, we anticipated that a similar M L trigonal
5
6
bipyramidal structure would self-assemble upon reaction of
A, p-anisidine, and cadmium(II) trifluoromethanesulfonate
À
1
(
OTf ; Section S1.7). The H NMR spectrum of this solution
was broad, with multiple signals for each proton, similar to
that of 4 (Figure S20). Single-crystal X-ray diffraction
revealed the structure of trigonal bipyramid 5 (Figure 3).
observation suggested that 4 was capable of binding CO as
2
2À
CO3 in a similar manner to 5. After seven days at 708C the
intensities of these new signals (relative to the carbonate-free
form) in the mass spectrum were found to increase, which we
2
À
inferred to result from an increase in CO3 concentration in
solution; only a slight broadening of the signals of 4 in the
1
H NMR spectrum was detected during this transformation
(Figure S24).
When helicate 2 was kept at room temperature open to air
for four weeks, no evidence of carbonate binding was evident
1
in the H NMR (Figure S25) or mass spectra (Figure S26).
+
À
When excess Me N BF (10 equiv) was added to a solution
4
4
1
of 2, the resonance signals in the H NMR spectrum of 2
immediately shifted, with the greatest change detected for the
protons orientated towards the interior of 2. Models suggest
À
that the cavity of 2 is sufficiently large for BF encapsulation
4
1
9
(
Figure S27). A single F NMR resonance signal, shifted
À
upfield with respect to free BF4 , was detected, suggesting
that BF4 ions were in fast exchange with the cavity of 2
À
Figure 3. a) Space-filling representation of the X-ray crystal structure of
in solution (Figure S28). ESI-MS also provided evidence
consistent with host–guest binding (Figure S29).
À
5, where b) two OTf ions (shown in space-filling model) occupy the
two binding pockets of 5 (shown as a framework). c) View down the
Under air over a two week period, the signals attributed to
long axis of the structure showing coordination of a carbonate ion to
À
1
II
[BF ꢀ2] in the H NMR spectrum decreased in intensity,
4
the equatorial Cd centers (apical metal centers are omitted for clarity).
with concomitant growth of new, broad signals, which were
comparable to the H NMR spectrum of 4. ESI-MS results
Atom colors: C=gray, N=blue, Cd =light yellow, H=white, F=light
blue, B=pink, O=red, S=dark yellow. Disorder, non-encapsulated
anions, and solvent molecules are omitted for clarity.
1
were consistent with the formation of trigonal bipyramid 4
1
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Chemie
containing bound carbonate (Figure S29). These observations
X-ray diffraction analysis indicated that two oxygen
donors from the bound sulfate dianion chelate one equatorial
À
suggest that the cavity of 4 must first be opened through BF4
À
II
II
or OTf templation before CO fixation may occur.
Zn metal center and the remaining two Zn sites each
coordinate to one oxygen from sulfate and to a water
molecule. Dissolution of the crystals in acetonitrile yielded
2
Based on the observation that 4 and 5 were capable of
fixing carbon dioxide as carbonate in solution, we hypothe-
sized that similar small-molecule capture might be possible
with sulfur dioxide (Section S3.2). When a solution of sulfur
dioxide in water was added to the subcomponents necessary
for the formation of 4 in acetonitrile in air, ESI-MS signals
were detected consistent with the formation of the sulfite
1
a H NMR spectrum with sharp signals (Figure S33), suggest-
ing that this anion was bound more strongly than the
previously detected carbonate or hydroxide anions. Peaks
attributable to bound carbonate in the ESI mass spectra were
not detected after bubbling CO through a solution of the
2
2
À
2À
(
SO3 ) adduct of 4 after 25 min stirring at 708C (Figures S30,
SO4 adduct of 4 at 708C over a two week period (Fig-
ure S34). Two signals for BF4 were evident in the F NMR
spectrum (Figure S35), attributable to bound and unbound
2À
À
19
S31). Sulfate (SO4 ) was present in the sulfur dioxide
solution as an impurity (approximately 18%); MS signals
corresponding to 4 with two equivalents of SO4 were also
2
À
19
1
anions, with a F– H HOESY indicating proximity between
the tetrafluoroborate anion and the inward-facing protons of
4 (Figure S37). We infer that the rate-limiting step of sulfite
oxidation occurs outside of the cavity of 4, given that no
difference was detected between oxidation rates in the
presence and absence of the host.
detected (Figure S32). After 25 min, the relative intensities of
2
À
the signals for the SO adduct of 4 in comparison to those of
4
2
À
the SO3 analogue were higher than those detected in
a control experiment monitoring sulfite oxidation (Fig-
2
À
ure S30), suggesting that a SO
guest was preferred over
4
2
À
SO3 . The rate of decrease in the intensity of the MS signals
attributed to the SO3 adduct, and the concomitant increase
In conclusion, the acute coordination vectors of ligands
derived from dialdehyde A have allowed for the construction
of two new metal–organic structure types, an M L rectangle
2
À
2
À
in the signals for the SO4 adduct, was consistent with a zero-
4
6
2
À
order rate of reaction in [SO ], as has been previously
and an M L trigonal bipyramid. The trigonal bipyramid is
5 6
3
[
32]
reported
(Figures S30b and c). Single-crystal X-ray dif-
fraction revealed the binding of one SO4 anion between the
equatorial metal sites (Figure 4).
capable of fixing carbon dioxide as carbonate and sulfur
dioxide as (oxidized) sulfate. Investigations are underway to
stabilize a variety of unstable anionic species using this
trigonal bipyramid structure.
2
À
Acknowledgements
This work was supported by the EU FP7 Marie Curie
Academic-Industrial Initial Training Network on Dynamic
Molecular Nanostructures (DYNAMOL; to C.B. and W.J.R.)
and the UK Engineering and Physical Sciences Research
Council (EPSRC). We thank the Diamond Light Source
(UK) for synchrotron beamtime on I19 (MT8464), the NMR
facility at the Department of Chemistry, University of Cam-
bridge, and the EPSRC UK National Mass Spectrometry
Facility at Swansea University.
Keywords: carbon dioxide fixation · host–guest systems ·
small-molecule transformations · supramolecular chemistry ·
template synthesis
How to cite: Angew. Chem. Int. Ed. 2015, 54, 11122–11127
Angew. Chem. 2015, 127, 11274–11279
[
[
1] T. R. Cook, P. J. Stang, Chem. Rev. 2015, DOI: 10.1021/
cr5005666.
2] a) A. W. Kleij, J. N. H. Reek, Chem. Eur. J. 2006, 12, 4218 – 4227;
b) G. H. Clever, Molecules at Work, Wiley-VCH, Weinheim,
2
012, pp. 13 – 37; c) M. J. Hardie, Chem. Soc. Rev. 2010, 39, 516 –
Figure 4. X-ray crystal structure of the sulfate adduct of 4 showing
a) the bound anions (sulfate and tetrafluoroborate) in space-filling
mode within the framework of 4, shown in wireframe representation.
b) View highlighting the chelation of the centrally bound sulfate by the
527; d) M. Albrecht, Activating Unreactive Substrates, Wiley-
VCH, Weinheim, 2009, pp. 411 – 425; e) M. Yoshizawa, J. K.
Klosterman, M. Fujita, Angew. Chem. Int. Ed. 2009, 48, 3418 –
3438; Angew. Chem. 2009, 121, 3470 – 3490.
II
three equatorial Zn centers (apical metal centers are removed for
[3] a) N. Gimeno, R. Vilar, Coord. Chem. Rev. 2006, 250, 3161 –
3189; b) R. M. Meudtner, S. Hecht, Angew. Chem. Int. Ed. 2008,
47, 4926 – 4930; Angew. Chem. 2008, 120, 5004 – 5008; c) I. A.
Riddell, M. M. J. Smulders, J. K. Clegg, Y. R. Hristova, B.
clarity). Atom colors: C=gray, N=blue, Zn=yellow, H=white,
F=light blue, B=pink, O=red, S=dark yellow. Non-encapsulated
anions and solvent molecules are omitted for clarity.
Angew. Chem. Int. Ed. 2015, 54, 11122 –11127
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org 11125

.
Angewandte
Communications
Breiner, J. D. Thoburn, J. R. Nitschke, Nat. Chem. 2012, 4, 751 –
56; d) H. T. Chifotides, I. D. Giles, K. R. Dunbar, J. Am. Chem.
Berseth, J. J. Sokol, M. P. Shores, J. L. Heinrich, J. R. Long, J.
Am. Chem. Soc. 2000, 122, 9655 – 9662.
7
Soc. 2013, 135, 3039 – 3055.
4] a) R. Chakrabarty, P. S. Mukherjee, P. J. Stang, Chem. Rev. 2011,
[15] a) K. S. Chichak, S. J. Cantrill, A. R. Pease, S.-H. Chiu, G. W. V.
Cave, J. L. Atwood, J. F. Stoddart, Science 2004, 304, 1308 – 1312;
b) J.-F. Ayme, J. E. Beves, C. J. Campbell, D. A. Leigh, Angew.
Chem. Int. Ed. 2014, 53, 7823 – 7827; Angew. Chem. 2014, 126,
7957 – 7961; c) D. A. Leigh, R. G. Pritchard, A. J. Stephens, Nat.
Chem. 2014, 6, 978 – 982; d) C. S. Wood, T. K. Ronson, A. M.
Belenguer, J. J. Holstein, J. R. Nitschke, Nat. Chem. 2015, 7,
[
1
11, 6810 – 6918; b) D. Fiedler, D. H. Leung, R. G. Bergman,
K. N. Raymond, Acc. Chem. Res. 2005, 38, 349 – 358; c) M. D.
Ward, Chem. Commun. 2009, 4487 – 4499; d) P. Ballester, Chem.
Soc. Rev. 2010, 39, 3810 – 3830; e) G. M. Whitesides, B. Grzy-
bowski, Science 2002, 295, 2418 – 2421; f) T. K. Ronson, S. Zarra,
S. P. Black, J. R. Nitschke, Chem. Commun. 2013, 49, 2476 –
3
54 – 358.
[16] R. W. Saalfrank, H. Maid, A. Scheurer, Angew. Chem. Int. Ed.
008, 47, 8794 – 8824; Angew. Chem. 2008, 120, 8924 – 8956.
2
490.
2
[
[
5] a) Z. J. Wang, C. J. Brown, R. G. Bergman, K. N. Raymond, F. D.
Toste, J. Am. Chem. Soc. 2011, 133, 7358 – 7360; b) Y. Kohyama,
T. Murase, M. Fujita, J. Am. Chem. Soc. 2014, 136, 2966 – 2969.
6] a) G. Zhang, O. Presly, F. White, I. M. Oppel, M. Mastalerz,
Angew. Chem. Int. Ed. 2014, 53, 5126 – 5130; Angew. Chem.
[
17] a) M. Burnworth, L. Tang, J. R. Kumpfer, A. J. Duncan, F. L.
Beyer, G. L. Fiore, S. J. Rowan, C. Weder, Nature 2011, 472, 334 –
3
8
37; b) J. R. Kumpfer, S. J. Rowan, ACS Macro Lett. 2012, 1,
82 – 887.
[
[
18] I. A. Riddell, T. K. Ronson, J. K. Clegg, C. S. Wood, R. A.
Bilbeisi, J. R. Nitschke, J. Am. Chem. Soc. 2014, 136, 9491 – 9498.
19] a) V. Amendola, L. Fabbrizzi, Chem. Commun. 2009, 513 – 531;
b) K. M. Mullen, P. D. Beer, Chem. Soc. Rev. 2009, 38, 1701 –
2
014, 126, 5226 – 5230; b) M. A. Little, M. E. Briggs, J. T. A.
Jones, M. Schmidtmann, T. Hasell, S. Y. Chong, K. E. Jelfs, L.
Chen, A. I. Cooper, Nat. Chem. 2015, 7, 153 – 159; c) I. A.
Riddell, M. M. J. Smulders, J. K. Clegg, J. R. Nitschke, Chem.
Commun. 2011, 47, 457 – 459.
1
713; c) P. A. Gale, N. Busschaert, C. J. E. Haynes, L. E.
Karagiannidis, I. L. Kirby, Chem. Soc. Rev. 2014, 43, 205 – 241;
d) G. O. Lloyd, J. W. Steed, Nat. Chem. 2009, 1, 437 – 442.
[
7] a) O. Chepelin, J. Ujma, X. Wu, A. M. Z. Slawin, M. B. Pitak,
S. J. Coles, J. Michel, A. C. Jones, P. E. Barran, P. J. Lusby, J. Am.
Chem. Soc. 2012, 134, 19334 – 19337; b) T. Heinz, D. M. Rudke-
vich, J. Rebek, Nature 1998, 394, 764 – 766; c) S. Mirtschin, A.
Slabon-Turski, R. Scopelliti, A. H. Velders, K. Severin, J. Am.
Chem. Soc. 2010, 132, 14004 – 14005; d) Y. Li, A. H. Flood, J.
Am. Chem. Soc. 2008, 130, 12111 – 12122; e) R. Custelcean, P. V.
Bonnesen, N. C. Duncan, X. Zhang, L. A. Watson, G. Van Ber-
kel, W. B. Parson, B. P. Hay, J. Am. Chem. Soc. 2012, 134, 8525 –
[
20] a) L. Raehm, L. Mimassi, C. Guyard-Duhayon, H. Amouri,
M. N. Rager, Inorg. Chem. 2003, 42, 5654 – 5659; b) H. Amouri,
L. Mimassi, M. N. Rager, B. E. Mann, C. Guyard-Duhayon, L.
Raehm, Angew. Chem. Int. Ed. 2005, 44, 4543 – 4546; Angew.
Chem. 2005, 117, 4619 – 4622; c) H. Amouri, C. Desmarets, A.
Bettoschi, M. N. Rager, K. Boubekeur, P. Rabu, M. Drillon,
Chem. Eur. J. 2007, 13, 5401 – 5407; d) C. Desmarets, C. Policar,
L.-M. Chamoreau, H. Amouri, Eur. J. Inorg. Chem. 2009, 4396 –
8
1
534; f) S. K. Samanta, M. Schmittel, Org. Biomol. Chem. 2013,
1, 3108 – 3115; g) S. Liu, A. D. Shukla, S. Gadde, B. D. Wagner,
4
400; e) S. Freye, J. Hey, A. Torras-Galµn, D. Stalke, R. Herbst-
Irmer, M. John, G. H. Clever, Angew. Chem. Int. Ed. 2012, 51,
191 – 2194; Angew. Chem. 2012, 124, 2233 – 2237; f) C. Klein, C.
A. E. Kaifer, L. Isaacs, Angew. Chem. Int. Ed. 2008, 47, 2657 –
660; Angew. Chem. 2008, 120, 2697 – 2700; h) G. H. Clever, S.
Tashiro, M. Shionoya, Angew. Chem. Int. Ed. 2009, 48, 7010 –
012; Angew. Chem. 2009, 121, 7144 – 7146.
2
2
Gütz, M. Bogner, F. Topi c´ , K. Rissanen, A. Lützen, Angew.
Chem. Int. Ed. 2014, 53, 3739 – 3742; Angew. Chem. 2014, 126,
7
3
814 – 3817; g) D. A. Safin, A. Pialat, A. A. Leitch, N. A.
[
[
8] a) Y. Ahn, Y. Jang, N. Selvapalam, G. Yun, K. Kim, Angew.
Chem. Int. Ed. 2013, 52, 3140 – 3144; Angew. Chem. 2013, 125,
Tumanov, I. Korobkov, Y. Filinchuk, J. L. Brusso, M. Murugesu,
Chem. Commun. 2015, 51, 9547 – 9550; h) I. A. Riddell, Y. R.
Hristova, J. K. Clegg, C. S. Wood, B. Breiner, J. R. Nitschke, J.
Am. Chem. Soc. 2013, 135, 2723 – 2733.
3
222 – 3226; b) D. Ray, J. T. Foy, R. P. Hughes, I. Aprahamian,
Nat. Chem. 2012, 4, 757 – 762.
9] a) Q.-F. Sun, J. Iwasa, D. Ogawa, Y. Ishido, S. Sato, T. Ozeki, Y.
Sei, K. Yamaguchi, M. Fujita, Science 2010, 328, 1144 – 1147;
b) M. Han, R. Michel, G. H. Clever, Chem. Eur. J. 2014, 20,
[
[
21] a) H. Nowell, S. A. Barnett, K. E. Christensen, S. J. Teat, D. R.
Allan, J. Synchrotron Radiat. 2012, 19, 435 – 441;
b) CCDC 1400514, 1400515, 1400516, 1400517 contain the
supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge
Crystallographic Data Centre.
1
0640 – 10644; c) T. Weilandt, U. Kiehne, J. Bunzen, G. Schna-
kenburg, A. Lützen, Chem. Eur. J. 2010, 16, 2418 – 2426.
[
10] C. Schouwey, J. J. Holstein, R. Scopelliti, K. O. Zhurov, K. O.
Nagornov, Y. O. Tsybin, O. S. Smart, G. Bricogne, K. Severin,
Angew. Chem. Int. Ed. 2014, 53, 11261 – 11265; Angew. Chem.
22] a) A. M. Castilla, W. J. Ramsay, J. R. Nitschke, Chem. Lett. 2014,
4
3, 256 – 263; b) R. W. Saalfrank, B. Hçrner, D. Stalke, J.
2
014, 126, 11443 – 11447.
11] A. Stephenson, M. D. Ward, Dalton Trans. 2011, 40, 10360 –
0369.
Salbeck, Angew. Chem. Int. Ed. Engl. 1993, 32, 1179 – 1182;
Angew. Chem. 1993, 105, 1223 – 1225; c) P. Mal, D. Schultz, K.
Beyeh, K. Rissanen, J. R. Nitschke, Angew. Chem. Int. Ed. 2008,
[
[
[
1
12] Y. Okazawa, K. Kondo, M. Akita, M. Yoshizawa, J. Am. Chem.
Soc. 2015, 137, 98 – 101.
4
7, 8297 – 8301; Angew. Chem. 2008, 120, 8421 – 8425; d) D. L.
Caulder, K. N. Raymond, J. Chem. Soc. Dalton Trans. 1999,
13] a) R. W. Saalfrank, A. Stark, M. Bremer, H.-U. Hummel, Angew.
Chem. Int. Ed. Engl. 1990, 29, 311 – 314; Angew. Chem. 1990,
1185 – 1200.
[23] B. R. Hall, H. Adams, M. D. Ward, Supramol. Chem. 2012, 24,
499 – 507.
1
02, 292 – 295; b) R. W. Saalfrank, H. Glaser, B. Demleitner, F.
Hampel, M. M. Chowdhry, V. Schünemann, A. X. Trautwein,
G. B. M. Vaughan, R. Yeh, A. V. Davis, K. N. Raymond, Chem.
Eur. J. 2002, 8, 493 – 497; c) D. L. Caulder, K. N. Raymond, Acc.
Chem. Res. 1999, 32, 975 – 982.
[24] F. Grepioni, G. Cojazzi, S. M. Draper, N. Scully, D. Braga,
Organometallics 1998, 17, 296 – 307.
[25] Z. R. Bell, J. C. Jeffery, J. A. McCleverty, M. D. Ward, Angew.
Chem. Int. Ed. 2002, 41, 2515 – 2518; Angew. Chem. 2002, 114,
2625 – 2628.
[26] a) S. Hiraoka, Y. Sakata, M. Shionoya, J. Am. Chem. Soc. 2008,
130, 10058 – 10059; b) J. C. Garrison, M. J. Panzner, P. D. Custer,
D. V. Reddy, P. L. Rinaldi, C. A. Tessier, W. J. Youngs, Chem.
Commun. 2006, 4644 – 4646; c) S. Cardona-Serra, E. Coronado,
P. Gavina, J. Ponce, S. Tatay, Chem. Commun. 2011, 47, 8235 –
[
14] a) C. Browne, S. Brenet, J. K. Clegg, J. R. Nitschke, Angew.
Chem. Int. Ed. 2013, 52, 1944 – 1948; Angew. Chem. 2013, 125,
1
2
998 – 2002; b) D. Luo, X.-P. Zhou, D. Li, Angew. Chem. Int. Ed.
015, 54, 6190 – 6195; c) Q.-G. Zhai, C. Mao, X. Zhao, Q. Lin, F.
Bu, X. Chen, X. Bu, P. Feng, Angew. Chem. Int. Ed. 2015, 54,
884 – 7888; Angew. Chem. 2015, 127, 7997 – 8001; d) P. A.
7
1
1126 www.angewandte.org
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2015, 54, 11122 –11127

Angewandte
Chemie
8
237; d) C. J. Kuehl, Y. K. Kryschenko, U. Radhakrishnan, S. R.
Seidel, S. D. Huang, P. J. Stang, Proc. Natl. Acad. Sci. USA 2002,
9, 4932 – 4936; e) M. Wang, C. Wang, X.-Q. Hao, X. Li, T. J.
[29] T. Steiner, Chem. Commun. 1997, 727 – 734.
[30] H. Effenberger, K. Mereiter, J. Zemann, Z. Kristallogr. 1981,
156, 233 – 243.
9
Vaughn, Y.-Y. Zhang, Y. Yu, Z.-Y. Li, M.-P. Song, H.-B. Yang, X.
Li, J. Am. Chem. Soc. 2014, 136, 10499 – 10507.
27] a) L. Alvarado, C. Brewer, G. Brewer, R. J. Butcher, A. Straka,
C. Viragh, CrystEngComm 2009, 11, 2297 – 2307; b) J. Olguín, M.
Kalisz, R. ClØrac, S. Brooker, Inorg. Chem. 2012, 51, 5058 – 5069;
c) N. K. Szymczak, L. A. Berben, J. C. Peters, Chem. Commun.
[31] a) S. K. Dey, R. Chutia, G. Das, Inorg. Chem. 2012, 51, 1727 –
1738; b) S. J. Brooks, P. A. Gale, M. E. Light, Chem. Commun.
2006, 4344 – 4346; c) T. Gunnlaugsson, P. E. Kruger, P. Jensen,
F. M. Pfeffer, G. M. Hussey, Tetrahedron Lett. 2003, 44, 8909 –
8913.
[
[
[32] V. Linek, V. Vacek, Chem. Eng. Sci. 1981, 36, 1747 – 1768.
2
009, 6729 – 6731.
28] W. Meng, T. K. Ronson, J. K. Clegg, J. R. Nitschke, Angew.
Chem. Int. Ed. 2013, 52, 1017 – 1021; Angew. Chem. 2013, 125,
Received: May 28, 2015
1
051 – 1055.
Published online: July 31, 2015
Angew. Chem. Int. Ed. 2015, 54, 11122 –11127
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org 11127