Synthesis of shape-persistent macrocycles with three 1,8-diazaanthracene units and their packing in the single crystal

Article abstract of DOI:10.1002/chem.201301798

The synthesis of four shape-persistent macrocycles with three 1,8-diazaanthracene units each is reported (2,3 a-3 c). For two of them single crystals could be obtained and the structures in the crystal be solved. The structures reveal that macrocycle 2 se

Full text of DOI:10.1002/chem.201301798

FULL PAPER
DOI: 10.1002/chem.201301798
Synthesis of Shape-Persistent Macrocycles with Three 1,8-Diazaanthracene
Units and Their Packing in the Single Crystal
Ming Li,[a] Frank-Gerrit Klꢀrner,[b] Junji Sakamoto,[a] and A. Dieter Schlꢁter*[a]
Abstract: The synthesis of four shape-
persistent macrocycles with three 1,8-
diazaanthracene units each is reported
(2,3a–3c). For two of them single crys-
tals could be obtained and the struc-
tures in the crystal be solved. The
prisingly it also forms a stable dimer in
solution. The reason for this is seen in
unusually efficient dispersion interac-
tions as a consequence of the large
contact areas in the dimer. All macro-
cycles are assessed as to their applica-
bility in lateral polymerizations in the
single crystal as well as in solution.
Keywords: crystal packing · macro-
cycles · shape-persistence · supra-
molecular self-dimerization
structures reveal that macrocycle
2
self-dimerizes in the solid state; sur-
Introduction
tent C2v-symmetric macrocycle 1 with two DAA units to-
wards a rigid rod polymer by photo-irradiation in the single
crystal,[11] whereby the DAA units were in fact packed anti-
parallel ftf resulting in a [4+4]-cycloaddition polymerization.
Encouraged by these results, we decided to make available
a collection of DAA-based monomers and to investigate in
depth their potential in context with the synthesis of 2DP
and their congeners, covalent monolayer sheets. These mon-
omers may also be of interest for novel types of double-
stranded hyperbranched polymers.[12]
Anthracenes (A)[1] and their heteroaromatic aza[2] and diaza
analogues[3] are important photochemically active units.
Light-induced dimerization via [4+4]-cycloaddition has been
studied in great detail particularly for homoaromatic anthra-
cenes and used for the creation of complex compounds[1,4]
and polymers[5] derived from simple components presenting
one or more of these units. Substituted As tend to furnish
anti dimers and aza-, as well as diazaanthracenes (DAA),
have an even stronger anti-preference.[2b,3,6] Recently, we
have started a program aiming at exploring shape-persistent
macrocyclic compounds[7] with two or three A or DAA units
for their ability to give polymers by photochemical treat-
ment, both in the solid state and at the air/water interface.
This led to the first two-dimensional polymer (2DP),[8] that
is, a covalent monolayer sheet polymer with topologically
planar repeat units,[9] and also a covalent monolayer sheet,
the internal structure of which still needs to be proven.[10]
The 2DP and the monolayer sheets were obtained by irradi-
ating a single crystal and a tight monomer assembly at the
air/water interface, respectively. While in the 2DP case the
A units of neighboring monomers were not face-to-face (ftf)
stacked, which resulted in a [4+2]-cycloaddition between
the A of one monomer and the acetylene of another, in the
sheet case it is assumed that the As are connected via
[4+4]-cycloaddition. We also polymerized the shape-persis-
Here we report a first important step into this matter, the
synthesis of compounds 2 and 3a–c which all carry three
DAAs and thus potentially qualify as monomers for lateral
polymerization in a single crystal (2,3a,3b), at an air/water
interface (3a) or in homogeneous solution (3c). We also de-
scribe first crystallization studies which in the case of com-
pounds 2 and 3a led to single crystals, the structures of
which could be solved by XRD. As will be shown, both
structures are not yet suited for 2D polymerization but pro-
vide valuable hints how to change crystallization to eventu-
ally arrive at a useful packing. The crystal packing of 2 is of
interest in its very own right in that this compound forms a
homo-dimer reminiscent of the commonly encountered het-
erodimeric supramolecular aggregates derived from, for ex-
ample, molecular tweezers and clips.[13] Because of the
scarce availability of supramolecular homo-dimers[14] the sta-
bility of the dimer of 2 was explored towards disassembly in
solution by NMR, UV/Vis, and fluorescence spectroscopy at
concentrations as low as 10À6 m and found to be virtually
negligible. The dimer was further investigated by MALDI-
ICR mass spectrometry and found to withstand also those
conditions. To find a reason for this surprisingly high stabili-
ty, the electrostatic surface potentials (ESP) of the two resi-
dues of the dimer were calculated by the semi-empirical
methods AM1 and PM3.[15] This led us to conclude that the
manifold dispersion interactions between the aromatic sub-
structures tightly ftf packed within the dimer sum up to a re-
[a] Dr. M. Li, Priv. Doz. Dr. habil. J. Sakamoto, Prof. Dr. A. D. Schlꢀter
Laboratory for Polymer Chemistry, Department of Materials
ETH Zurich, HCI J541, Wolfgang-Pauli-Strasse 10
8093 Zꢀrich (Switzerland)
E-mail: ads@mat.ethz.ch
[b] Prof. Dr. F.-G. Klꢁrner
Institute of Organic Chemistry, University of Duisburg-Essen
45117 Essen (Germany)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201301798.
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spectable value which together with an efficient dipol
moment compensation results in a stable dimer. Any sub-
stantial compensation of ESP, which is often encountered in
tweezers and clips, can be ruled out as driving force in this
case. Finally, compounds 3a–c will be briefly discussed in
terms of their applicability for lateral polymerizations where
particularly 3a but also 3c are believed to have a great po-
tential (Figure 1).
scale. The overall yield was 7% which is considered reason-
able given the complexity of the macrocycle.[16] Macrocycle
2 and compounds 5b, 5c, 5d were purified by recycling (r)-
GPC, compound 7a by silica gel column chromatography
and compound 7b by easy filtration and washing.
Synthesis of macrocycles 3a–c is delineated in Schemes 2
and 3. The bridging building blocks 12 and 13 were synthe-
sized from the known 3-bromo-5-iodo-toluene (8).[17] The
different reactivity of its two
halogens was used for the selec-
tive Sonogashira coupling with
TIPSA. The remaining bromide
was further reacted with bis(pi-
nacolato)diboron under palladi-
um catalysis to give 10. Double
Suzuki coupling of 9 with 3,5-
dibromobenzyl alcohol[17] af-
forded 11. This reaction was
particularly easy to perform
and gave compound 11 in quan-
tities of up to 50 g. Complete
desilylation of 11 with tetrabu-
tylammonium fluoride (TBAF)
resulted in 12, while the mono-
desilylation of 11 with TBAF in
a 1.15:1 stoichiometry afforded
13 after purification. All com-
pounds were purified by silica
gel column chromatography.
Synthesis of macrocycle 3a
started from the DAA deriva-
tive 4 which was coupled either
with the terphenylene bridging
unit 12 to give 14 or with unit
13 to furnish 15. Deprotection
of 15 to give macrocycle precur-
sor 16 had to be performed at
08C to avoid black insoluble
precipitate which most likely
was the product of an uncon-
trolled oligomerization of de-
protected acetylenes. The two
precursors 14 and 16 were cy-
Figure 1. Chemical structures of compounds synthesized in this study. Macrocycle 1 has two 1,8-diazaanthra-
cene (DAA) units while macrocycles 2 and 3a–c have three. Compound 2 is shown in two representations.
The letters refer to NMR signal assignment in Figures 2 and 4. The assignment of macrocycle 1 follows that of
2.
Synthesis of macrocycles 2 and 3a–3c: Synthesis of com-
pound 2 (Scheme 1) started from the previously reported
building blocks dibromo-DAA 4, bridge 5a, and cyclization
precursor 6.[11] Mono substitution of 5a with tri(isopropylsi-
lyl)acetylene (TIPSA) afforded 5b, and further substitution
with tri(methylsilyl)acetylene (TMSA) afforded 5c. TIPS
and TMS-protected component 5c was then converted into
5d by selective removal of the TMS group in aqueous
KOH. Next, precursor 7b was prepared by a twofold inter-
molecular Sonogashira coupling between 4 and 5d leading
to 7a, followed by TIPS removal. In the final step, the two
complementary precursors 6 and 7b were cyclized in a 1:1
stoichiometry in a dilute DMF solution (0.2 mm). This pro-
cedure furnished macrocycle 2 on a rather useful 100 mg
clized in diluted solution (2.0 mm) using a 1:1 stoichiometry
furnishing macrocycle 3a on a 600 mg scale (total yield: 5%
from 4 and 8) starting from more than a gram of both 14
and 16.
Macrocycle 3a served as starting material for capped de-
rivative 3b and the alkyl-chain decorated derivate 3c. Un-
fortunately, the capping procedure with trimesoyl chloride,
turned out to be extremely low yielding and also poorly re-
producible. Nevertheless a few mg of this material could be
obtained (estimated total yield: <1%) and its existence
proven by NMR spectroscopy (Figure 2) and high resolution
MALDI ICR mass spectrometry (see below). The esterifica-
tion of 3a with n-dodecanoyl chloride went much better and
afforded the expected macrocycle 3c reliably on a 70–75 mg
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Synthesis of Shape-Persistent Macrocycles
FULL PAPER
3c which reflects the incorpora-
tion of an aromatic ester cap
and aliphatic ester chains, re-
spectively. Other characteristic
signals include the methyl
group at d
ꢀ
2 ppm for all
three compounds and the aro-
matic hydrogens (g) of the cap
in 3b. More assignments are
given in Figure 2. Note that
there is no indication of homo-
dimer formation. The UV/Vis
spectra of macrocycles 3a–c
have the typical p–p* absorp-
tions of the DAA unit at l=
380–480 nm similar to other an-
thracenes (Figure S18).
Single crystal X-ray structures
of macrocycle 2 and 3a: Cubic
crystals of 2 were grown by
slow liquid diffusion of super-
natant toluene into a chloro-
form solution (Figure 3a). For
this purpose a necked vial was
used the bottom part of which
was filled up to the neck with
the chloroform solution before
the upper part was charged
with toluene. This macrocycle
crystallizes in a rectangular con-
formation (Figure 3b) and, un-
expectedly, two such macrocy-
cles mutually penetrate each
other to give
a homodimer
(Figure 3c). The representation
in Figure 3b and c and the
color code (red and grey)
should facilitate understanding
the dimer structure. Note that
the DAA units in both residues
of such a dimer pair are orient-
ed parallel to one another but
Scheme 1. Synthesis of macrocycle 2 with conditions.
in opposite direction. The DAA
units of one monomer are posi-
1
scale (total yield: 2% from 4 and 8). The H and 13C NMR
spectra of all compounds are provided in Figures S1–S17.
Macrocycles 3a–c were analyzed by HR-MALDI ICR
tioned at close distance to the bridging units of the other
monomer and vice versa. Figure 3d shows two views of the
resulting two stacks of DAA (residue1), bridge (residue2),
DAA (residue1), and bridge (residue2) units contained in
each dimer. For clarity, all other parts of the molecular
structures are removed. The distances between neighboring
units are well below 4 ꢃ which suggests effective stacking
interactions. For a discussion of the driving forces for dimer
formation, see below. Interestingly the dimers are arranged
into straight arrays (Figure 3e) whereby stacking interac-
tions are again operative. This time it is the pyridine moiet-
ies contained in the bridging units which are oriented anti-
mass spectrometry and H and 13C NMR spectroscopy. The
1
mass spectra gave the molecular ions [M+H+] of 3a, 3b
and 3c at m/z 1579.6187 (calcd: 1579.6208), 1736.6094
(calcd: 1736.6088) and 2126.1233 (calcd: 2126.1220), respec-
tively. In addition, both H and 13C NMR spectra show the
1
expected (small) set of signals in accordance with molecular
symmetry. Figure 2 compares the H NMR spectra. The sig-
nals of the benzylic hydrogen atoms (e) shift from d=
4.85 ppm in 3a to d=5.65 ppm in 3b and to d=5.04 ppm in
1
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A. D. Schlꢀter et al.
parallel to one another at a dis-
tance of approximately 3.8 ꢃ
(Figure 3 f).
Cubic crystals of macrocycle
3a were grown from CHCl3
(Figure 3). The macrocycles
fold-up resulting in two of their
DAA units to give a somewhat
off-set ftf dimer. The remaining
DAA unit is involved in an in-
termolecular ftf-stacking with
its counterpart of the neighbor-
ing macrocycle. Stacking is
again off-set and next neighbors
are turned upside down. Fig-
ure 3i gives typical distances in
these ftf-stackings.
Scheme 2. Synthesis of terphenylene bridging units 12 and 13 with conditions.
Discussion
The single crystals of 2 and 3a show a highly interesting
packing of the macrocyles in the crystal lattice, which is,
however, unfavorable for any photochemically induced poly-
merization. Macrocycle 2 forms intimate dimers which are
interesting in their own right but, even though there are sur-
prising cases of innercrystal mobility,[18] it is safe to assume
that irradiation of crystals of 2 will not result in 2D poly-
mers. However, as stacking enhances p orbital overlap, the
dimer crystals may be interesting candidates to explore, for
example, directed charge carrier mobility.[19] For 3a at best
one may achieve a dimerization of the DAA pairs between
neighboring compounds. Despite the off-set within these
pairs, the distances of both DAA units (Figure 4c, bottom)
are still within the range for topochemical reactions, as first
described by Schmidt.[20] Regarding macrocycle 3b it is
noted that although only a very small amount of this com-
pound was synthesized, crystals could be grown (Fig-
ure S19). Unfortunately, they contained too many defects
for structure determination. Thus, despite its rather promis-
ing design,[8] 3b is not a useful monomer for polymerization
studies unless the synthetic difficulties with introducing the
cap and with crystallization can be overcome. It is notewor-
thy that the packing of both monomers 2 and 3a while
being rather different seems to be driven by the same desire
namely to prevent the cyclesꢄ interior voids from being
“empty”. Both the homo-dimer of 2 and the tightly self-
folded 3a have virtually no residual void. We believe that
this interpretation provides the key to eventually rendering
these macrocycles into successful monomers. One can well
imagine that, if offered an attractive guest for their voids,
the macrocycles would co-crystallize as 1:1 host/guest com-
plexes presenting their DAA units in a fixed geometry with
1208 between the DAAs. This could then very well result in
layered packing with these complexes being arranged alter-
natingly up and down and all their DAA units being ftf
stacked. Experiments in this direction are on-going. It may
Scheme 3. Synthesis of macrocycles 3a–c with conditions.
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Synthesis of Shape-Persistent Macrocycles
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tical rhombic conformations,
and also in the solid state it as-
sumes similar collapsed confor-
mations to prevent the void and
maximize stacking interactions.
In
sharp
contrast,
the
in
1H NMR spectrum of
2
[D2]TCE solution at room tem-
perature is astoundingly com-
plex (Figure 4b), rendering an
assignment practically impossi-
ble, and the complexity remains
basically unchanged even if the
temperature is raised from 298
to 383 K. This suggests that
macrocycle 2 forms a rather
stable supramolecular complex
whereby the symmetry is
broken and (unresolved) dy-
namic effects cause line broad-
ening. Given the fact that this
Figure 2. 1H NMR spectra of macrocycles 3a in [D6]DMSO at 370 K (a), 3b in [D2]TCE (tetrachloroethane)
at 350 K (b) and 3c in [D6]-benzene at 338 K (c). Signal assignment refers to Figure 1.
also be of interest to raise the question why macrocycle 2
forms a dimer and 3a does not. The main structural differ-
ence between these two compounds are i) the ethanylene
bridges connecting the three phenylene units in the hetero-
terphenylene units of 2 and ii) the hetero-terphenylene
bridge in 2 containing a para-methoxyphenylpyridyl frag-
ment. While the ethanylene bridges effectively coplanarize
the terphenylene units and thus render ftf stacking between
them and the next neighborꢄs DAA units energetically more
favorable, the pyridyl fragment significantly adds to com-
poundꢄs 2 overall dipole moment which is effectively com-
pensated in the dimer, the two residues of which are stacked
antiparallel. It is thus understandable that 2 has a higher
propensity to self-dimerize than 3a.
Finally, monomer 3a is an attractive candidate for interfa-
cial polymerization. It is amphiphilic and should either be
directly spreadable at an air/water interface or after its three
hydroxyl groups have been converted into short ethyleneoxy
substituents.[21] Monomer 3c finally is fully soluble even in
highly concentrated benzene solution which is the pre-requi-
site for a successful polymerization into the corresponding
double-stranded hyperbranched polymer. Such hyper-
branched polymers are unique because of their structure-en-
forced tendency to assume ellipsoidally flattened coils in sol-
ution.[22]
We shall now discuss qualitative experimental studies
aiming at determining the stability of dimer 2 towards de-
aggregation and computational studies aiming at under-
standing the reasons for its stability. Figure 4a depicts the
1H NMR spectrum of 1, which is the lower homologue of 2
and therefore contains only two instead of three repeat
units. From its simplicity and the C2v symmetry of 1, it is
concluded that this spectrum refers to an individual com-
pound rather than a dimer. Also there is no indication for
dimer formation of 1 in the crystal.[11] Thus, macrocycle 1 in
solution oscillates fast on the NMR timescale between iden-
macrocycle in the crystal forms a dimer, we assume that the
same applies to the solution, however, the dimerꢄs geometric
parameters now being somewhat flexible. The NMR spectra
remained unchanged even if solutions with concentrations
down to 10À3 m were recorded. Remarkably, the signal of the
methoxy hydrogen atoms e is the one least affected by this
complexation, suggesting that it is furthest away from the
central part of the dimer. The lower concentration range
was explored by UV/Vis and fluorescence spectroscopy. Fig-
ure S20 shows the UV/Vis spectra of 2 at concentrations of
10À3, 10À4 and 10À5 m in chloroform and Figure S21 displays
the corresponding fluorescence spectra in the concentration
range from 10À3–10À6 m. Neither of these spectra shows any
significant concentration dependence. Thus, if there is equili-
brium between monomer and dimer, it is entirely on the
dimer side. We further substantiated this aspect by high res-
olution MALDI-ICR mass spectrometry of a sample in
which macrocycle 2 was prepared with DCTB matrix. The
spectrum showed the dimer molecular ion at m/z 3765.3877
(calcd for C270H174N18O6 [M+H]+: 3765.4015) (Figure S22)
which is noteworthy because of the long dwelling time in
ICR mass spectrometry between ionization and detection fa-
voring disassembly.
The interaction between aromatic components has been
studied in quite some detail.[23] Electrostatic and dispersive
forces are the main sources of this interaction. To find out
what the driving force for dimer formation was the electro-
static potential surfaces of macrocyles 1, 2 and diethynyl-
substituted DAA derivative 17 and bridging unit 18 (the two
potential aromatic binding sites of 1 and 2) were calculated
by the semi-empirical methods AM1 and PM3.[15] The mo-
lecular structures were also optimized by these methods
(Figure S23). The EPS calculations were helpful for the un-
derstanding and explanation why various aromatic host mol-
ecules such as cyclophanes or molecular tweezers bind pref-
erentially positively charged guest molecules.[13,24] Contrary
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A. D. Schlꢀter et al.
DAA unit slightly less negative
than that of the aromatic bridg-
ing unit (Figure S23). Thus,
there is no obvious attractive
electrostatic interaction be-
tween these two units in the
dimer of 2. However, in these
extended aromatic systems mul-
tiple dispersive interactions are
certainly the dominating nonco-
valent binding force which
binds the two molecules togeth-
er.
Conclusion
In summary, four different mac-
rocycles with three DAA units
each, 2 and 3a–c, were synthe-
sized. For two of them, 2 and
3a, single crystals were grown
and the structure be solved by
XRD. While these crystals in
their present form are not suita-
ble for photochemically in-
duced solid-state polymeriza-
tion, co-crystallization seems a
promising way to nevertheless
achieve this goal. The crystals
of 2 revealed an unexpected
tendency of this macrocycle to-
wards self-assembly into a ho-
modimer. The propensity of the
dimer towards disaggregation in
solution was investigated at ele-
vated temperature and at con-
centrations as low as 10À6 m and
found to be negligible. The
dimer was stable under all ap-
plied conditions including in
the MALDI ICR mass spec-
trometer which sets it apart
from other supramolecular
dimers, which involve CH–
aryl,[25] aryl–aryl[26] and H-bond-
ing[27] interactions and are less
stable towards dissociation.
Electrostatic potential surface
calculations suggest that disper-
sion interactions are the re-
sponsible factor behind this sta-
bility whereby the unusually
Figure 3. Single crystal of macrocycle 2: a) Optical microscopy image of crystal habit. b)–f) Packing in the
crystal: b) Approach of two macrocycles (red and grey) to illustrate dimer formation. Arrows indicate the op-
posite orientations of DAA moieties. c) Self-assembled dimer. d) Two views of truncated dimer to show the
packing of the DAA units of one macrocycle with the bridging units of the other in the same dimer. e) Top
view of the 1D array of dimers. f) Side view of the truncated 1D array to illustrate packing of the dimer bridg-
ing units. Solvent molecules are disordered and crystallographically not resolved. Single crystal of macrocycle
3a: g) Optical microscopy image of crystal habitus. h)–j) Packing in the crystal: h),j) Two different perspec-
tives tilted by 908 of two neighboring macrocycles showing that two of the DAA units of each compound are
intramolecularly ftf-stacked while one DAA unit of each macrocycle form an intermolecular ftf stacking. Both
stackings are somewhat off-set i) which prevents [4+4]-cycloadditions across the 9,10-positions (up: intermo-
lecular; down: intramolecular).
to these host–guest systems, where, for example, the tweez-
ersꢄ arene units show a profoundly negative EPS comple-
mentary to the positive guest EPS, the EPS of both aromatic
binding sites of macrocycle 1 and 2 is negative, that of the
large number of tight contacts between the two residues of
the dimer obviously sums up to considerable overall interac-
tion energy. Compounds 3a and 3c are promising monomers
for interfacial polymerization at the air/water interface and
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Synthesis of Shape-Persistent Macrocycles
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[10] P. Payamyar et al. unpublished results.
[11] M. Li, A. D. Schlꢀter, J. Sakamoto, J. Am. Chem. Soc. 2012, 134,
11721–11725.
[12] For hyperbranched polymers, see: B. Voit, J. Polym. Sci. Part A
2000, 38, 2505–2525; B. Voit, A. Lederer, Chem. Rev. 2009, 109,
5924–5973. For double-stranded ladder polymers, see: A. D. Schlꢀt-
er, Adv. Mater. 1991, 3, 282–291; A. D. Schlꢀter, M. Lçffler, V. En-
kelmann, Nature 1994, 368, 831–834. M. Servalli, A. D. Schlꢀter, J.
Sakamoto, in preparation. For novel double-stranded hyperbranched
polymers, see: M. Servalli, J. Sakamoto, in preparation.
[13] F.-G. Klꢁrner, B. Kahlert, Acc. Chem. Res. 2003, 36, 919–932; M.
Harmata, Acc. Chem. Res. 2004, 37, 862–873. F.-G. Klꢁrner, T.
Schrader, Acc. Chem. Res. 2013, 46, 967–978.
[14] B. Branchi, V. Balzani, P. Ceroni, M. Campana Kuchenbrandt, F.-G.
Klꢁrner, D. Blꢁser, R. Boese, J. Org. Chem. 2008, 73, 5839–5851.
[15] The EPS calculations of the compounds 1, 2, 17, and 18 were per-
formed with AM1 and PM3 implemented in Spartan’04, Wavefunc-
tion, Inc. Irvine, CA, USA.
[16] C. Grave, A. D. Schlꢀter, Eur. J. Org. Chem. 2002, 3075–3098.
[17] P. Kissel, S. Breitler, V. Reinmꢀller, P. Lanz, L. Federer, A. D.
Schlꢀter, J. Sakamoto, Eur. J. Org. Chem. 2009, 2953–2955.
[18] J. M. Thomas, Pure Appl. Chem. 1979, 51, 1065–1082; V. Enkel-
mann, Adv. Polym. Sci. 1984, 63, 91–136; G. Kaupp, CrystEng-
Comm 2003, 5, 117–133; R. Morꢅ, G. Busse, J. Hallmann, C. Paul-
mann, M. Scholz, S. Techert, J. Phys. Chem. C 2010, 114, 4142–4148.
[19] J.-L. Bredas, J. P. Calbert, D. A. da Silva Filho, J. Cornil, Proc. Natl.
Acad. Sci. USA 2002, 99, 5804–5809; D. A. Curtis, J, Cao, J. W.
Kampt, J. Am. Chem. Soc. 2004, 126, 4318–4328; X. Chi, D. Li, H.
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[20] M. D. Cohen, G. M. J. Schmidt, J. Chem. Soc. 1964, 1996–2000;
G. M. J. Schmidt, Solid State Photochemistry, Verlag Chemie, Wein-
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[21] The amphiphilicity of 3a should result in a clear orientation at the
air/water interface with the hydroxyl or oligoethyleneoxy groups
pointing into the aqueous phase while the DAA units are positioned
at more or less the same altitude above the interface potentially al-
lowing for DAA stacking-driven order formation with subsequent
photoirradiation-induced lateral polymerization Y. Chen, M. Li, J.
Sakamoto, A. D. Schlꢀter, in preparation.
Figure 4. 1H NMR spectra of macrocycles 1 (a) and 2 at 298 K (b) and
383 K (c) in [D2]TCE. (Internal standard: d TCE =6 ppm). For signal as-
signment, see Figure 1.
solution polymerization towards novel hyperbranched poly-
mers, respectively.
Acknowledgements
We thank Dr. W. B. Schweizer and M. Solar, X-ray facility of the Labora-
tory of Organic Chemistry, ETHZ, for solving the X-ray structures and
Dr. A. Khan, ETHZ, and Dr. P. Kissel, UNR, for helpful discussions. We
are also grateful to L. Bertschi and R. Hꢁfliger, mass spectrometry unit
of the Laboratorium fꢀr Organische Chemie der ETHZ for their compe-
tent help with mass spectrometric analysis. Finally, we thank Prof. P.
Smith and Dr. K. Feldmann, both ETHZ, for access to and help with op-
tical microscopy.
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Received: May 10, 2013
Published online: && &&, 0000
Chem. Eur. J. 2013, 00, 0 – 0
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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These are not the final page numbers!

A. D. Schlꢀter et al.
The perfect fit: Two shape-persistent
macrocycles such as A form a self-
assembled dimer in the single crystal
which even under forcing conditions in
solution cannot be made to dissociate
into the single components.
Macrocycles
M. Li, F.-G. Klꢀrner, J. Sakamoto,
A. D. Schlꢁter* ............... &&&& — &&&&
Synthesis of Shape-Persistent Macrocy-
cles with Three 1,8-Diazaanthracene
Units and Their Packing in the Single
Crystal
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www.chemeurj.org
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 0000, 00, 0 – 0
ÝÝ
These are not the final page numbers!