Confined Spaces in [n]Cyclo-2,7-pyrenylenes

Article abstract of DOI:10.1002/anie.202102809

A set of strained aromatic macrocycles based on [n]cyclo-2,7-(4,5,9,10-tetrahydro)pyrenylenes is presented with size-dependent photophysical properties. The K-region of pyrene was functionalized with ethylene glycol groups to decorate the outer rim and thereby confine the space inside the macrocycle. This confined space is especially pronounced for n=5, which leads to an internal binding of up to 8.0×10⁴ m^?1 between the ether-decorated [5]cyclo-2,7-pyrenylene and shape-complementary crown ether–cation complexes. Both the ether-decorated [n]cyclo-pyrenylenes as well as one of their host–guest complexes have been structurally characterized by single-crystal X-ray analysis. In combination with computational methods the structural and thermodynamic reasons for the exceptionally strong binding have been elucidated. The presented rim confinement strategy makes cycloparaphenylenes an attractive supramolecular host family with a favorable, size-independent read-out signature and binding capabilities extending beyond fullerene guests.

Full text of DOI:10.1002/anie.202102809

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: Confined Spaces in [n]Cyclo-2,7-pyrenylenes
Authors: Niklas Grabicki, Khoa T. D. Nguyen, Steffen Weidner, and
Oliver Dumele
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.202102809
Link to VoR: https://doi.org/10.1002/anie.202102809

10.1002/anie.202102809
Angewandte Chemie International Edition
COMMUNICATION
Confined Spaces in [n]Cyclo-2,7-pyrenylenes
Niklas Grabicki,[a] Khoa T. D. Nguyen,[a] Steffen Weidner,[b] Oliver Dumele[a],*
[a]
N. Grabicki, K. T. D. Nguyen, O. Dumele,
Department of Chemistry
Humboldt Universität zu Berlin
Brook-Taylor-Straße 2, 12489 Berlin, Germany
E-mail: oliver.dumele@hu-berlin.de
Homepage: www.dumelelab.com
S. Weidner
[b]
Bundesanstalt für Materialprüfung
Federal Institute for Material Research and Testing
Richard-Willstätter-Straße 11, 12489 Berlin, Germany
Supporting information for this article is given via a link at the end of the document.
In memory of Prof. François Diederich
Abstract: A set of strained aromatic macrocycles based on [n]cyclo-
2,7-(4,5,9,10-tetrahydro)pyrenylenes is presented with size-
dependent photophysical properties. The K-region of pyrene was
functionalized with ethylene glycol groups to decorate the outer rim
and thereby confine the space inside the macrocycle. This confined
space is especially pronounced for n = 5, which leads to an internal
Herein, we report on a series of highly functionalized [n]cyclo-
2,7-(4,5,9,10-tetrahydro)pyrenylenes (CPYs) as supramolecular
hosts with confined binding cavities. The rich chemistry developed
on the pyrene scaffold and the reported [4]cyclo-2,7-pyrenylene
by Yamago and co-workers (Figure 1, top) make this polycyclic
aromatic hydrocarbon
functionalized aromatic macrocycles.[34,35] The molecular shape of
pyrenylene and shape complementary crown ether–cation complexes. the pyrene subunit leads to a -conjugated concave inner host
a feasible starting point for highly
binding of up to 8.0×104 –1 between the ether-decorated [5]cyclo-2,7-
M
Both, the ether-decorated [n]cyclo-pyrenylenes as well as one of their
host–guest complexes have been structurally characterized by single-
crystal X-ray analysis. In combination with computational methods the
structural and thermodynamic reasons for the exceptionally strong
binding have been elucidated. The presented rim confinement
strategy makes cycloparaphenylenes an attractive supramolecular
host family with a favorable, size-independent read-out signature and
binding capabilities extending beyond fullerene guests.
surface, creating an accessible volume suitable for host–guest
interactions.
Strained aromatic macrocycles have distinct properties compared
to their linear counterparts such as shape persistence, enhanced
solubility, and the ability to complex guests in their cavities.[1–3]
Among them, cycloparaphenylenes (CPPs) have gained much
interest in the last decade due to their size-dependent
photophysical and electronic properties.[4–7] Several bottom-up
strategies have been developed to synthesize CPPs or
derivatives containing hetero- or polycyclic aromatic moieties.[8–12]
Incorporation of such moieties allows to study new functionality
within this class of macrocycles and alter their photophysical and
electronic properties.[13–17] Moreover, the developed synthetic
methodology can be used to extend the molecular shape from a
macrocycle to a cage.[18–21] While molecular cages intrinsically
favor guest inclusion, CPPs and related strained carbon
macrocycles have been of limited use as supramolecular hosts,
most prominently for fullerenes.[22–27] However, a higher degree of
functionalization in combination with spatial extension of the cyclic
structure could enable turning CPPs into a relevant class of
supramolecular hosts.
Figure 1. Comparison of the accessible inner space between
a non
functionalized [n]cyclo-2,7-pyrenylene (CPY) and highly functionalized
a
[n]cyclo-2,7-(4,5,9,10-tetrahydro)pyrenylene derivative (not all ethylene glycol
groups are shown for clarity (n = 4)).
The K-region of pyrene was symmetrically functionalized via
Ru-catalyzed oxidation to obtain pyrene-4,5,9,10-tetrone (5).[36]
Acid-catalyzed condensation with ethylene glycol readily yielded
the wall fragment 4 of the desired macrocyclic structure
(Figure 2a).[37,38] We turned to regioselective Ir-catalyzed C–H
borylation of
4
to efficiently produce 3.[39] Subsequent
transmetallation with dichloro(1,5-cyclooctadiene)platinum(II)
gave the macrocyclic precursor 2.[11,40,41] This organometallic
precursor is accessible in gram-scale within four steps from
pyrene without the need of column chromatography. Reductive
elimination using triphenylphosphine resulted in the targeted
Regarding their intrinsic rigidity and their size dependent
UV/vis absorption and emission, carbon nanorings are unique
compared to other supramolecular host structures, such as
calix[n]arenes, resorcin[n]arenes, and cucurbit[n]urils.[28–31]
Improved guest binding should therefore enhance the applicability
of these intrinsically porous and shape persistent molecules in a
variety of research areas they are currently investigated for.[32,33]
CPYs 1[ ] as a crude reaction mixture of five different macrocycle
n
sizes 1[4–8] as observed by MALDI-TOF MS (Figure 2b). The
different congeners were separated by recycling gel permeation
chromatography (GPC).
1
This article is protected by copyright. All rights reserved.

10.1002/anie.202102809
Angewandte Chemie International Edition
COMMUNICATION
Figure 2. a) Synthesis of 1[4–8] starting from pyrene. Reagents and conditions: I) RuCl3, NaIO4, CH3CN/CH2Cl2/H2O, 0 °C, 30 min, then 25 °C, 2 h; II) ethylene
glycol, camphorsulfonic acid, MeOH, 120 °C, 24 h; III) 4,4'-di-tert-butyl-2,2'-bipyridine, [Ir(OMe)(COD)]2, bis(pinacolato)diboron, 1,4-dioxane, 120 °C, 18 h; IV)
[PtCl2(COD)], CsF, CH2Cl2, 45 °C, 24 h; V) PPh3, 1,2-dichlorobenzene, 180 °C (microwave), 1 min. MALDI-TOF mass spectra of b) the filtered crude reaction
mixture of step V and c) the isolated macrocycles 1[4–8]. d) Single-crystal X-ray structures of 1[4] and 1[6], H-atoms and solvent molecules (except for the ones inside
the cavity) are omitted for clarity, thermal ellipsoids are shown at 50% probability at 100 K. COD = cycloocta-1,5-diene.[77]
Formation of various ring sizes is a common feature,
observed in several examples following the platinum mediated
macrocyclization.[42–46] While the origin of this effect is still not fully
understood, the result is beneficial in the presented example, as
a systematic series of hosts with various sizes are obtained in a
one-pot synthesis. During the analysis of the Pt-containing
macrocyclic precursor, we have detected exclusively the mass of
tetrameric 2 via MALDI-TOF MS (see Figure S21 in the
Supporting Information), nevertheless formation of other Pt-ring
sizes appears plausible in regard of the literature.[42–46] The
H⋅⋅⋅Ohost hydrogen bonds (3.1–3.3 Å heavy atom distance) and
several remarkable C–Cl⋅⋅⋅Ohost halogen bonds (2.7–3.3 Å)
(Figure 2c, for a detailed analysis on the complex interaction
network between 1[6] and the solvent CHCl3 see Supporting
Information Figure S36–S38).
The UV/vis absorptions of the series 1[4–8] show similar
absorption maxima max for all macrocycle sizes (Figure 3 and
Table 1), which is a typical property for this class of macrocycles
originating from a formally Laporte-forbidden optical HOMO–
LUMO transition.[6,53,54] Exceptions to this forbidden transition
result in a red-shifted shoulder of all absorption maxima (400–
450 nm). While the entire series of 1[4–8] shows rather large
present triphenylphosphine leads to the formation of Pt(PPh3)4–n
,
which is known to insert into strain-activated C–C bonds. Dynamic
insertion of active Pt(PPh3)4–n into the C–C bond between
pyrenylene units and subsequent ligand exchange of cyclic
fragments can therefore be an explanation for the observed
variety of ring sizes.[12,47–49]
The 1H NMR spectra show a single signal in the aromatic
region for each macrocycle 1[n] owing to their average Dnh (n = 4–
8) symmetry (Figure S8–S19).[50] Due to the limited solubility of
1[8] full characterization by NMR was not possible, pointing
towards the feasible limitations in terms of ring-size for the
presented macrocycles. Unambiguous structural proof was
[77]
obtained by single-crystal X-ray diffraction for 1[4–6]
.
Carbon-
rich CPP-type macrocycles often exhibit a dense herringbone
crystal packing, reducing the intrinsic porosity (Figure S34 and
S39 for a detailed analysis).[33,51,52] In contrast, the solid state
structures of 1[4] and 1[6] exhibit a slipped-stacked tubular packing
presumably caused by the sterically demanding ethylene glycol
groups preventing a self-filling assembly in the solid state.
Crystals suitable for X-ray analysis of 1[5] could only be obtained
in the presence of a guest. The defined tubular stacking of this
structure can therefore not be compared to the other series
members. The crystal structure of 1[6] shows well resolved
chloroform molecules, structurally positioned by weak Cl3C–
Figure 3. a) UV/vis absorption (solid lines) and emission (dashed lines) spectra
of 1[4–8] (CHCl3, 25 °C). b) Molecular strain energies calculated using
a
homodesmotic model and StrainViz (B3LYP/6-31G(d)). c) Graphical
representation of the strain distribution for 1[4] given by StrainViz.
2
This article is protected by copyright. All rights reserved.

10.1002/anie.202102809
Angewandte Chemie International Edition
COMMUNICATION
Figure 4. Ball-and-stick representation of the X-ray (1[4–6]) and the geometry optimized (DFT) structures 1[7–8] containing the calculated cavity volume using the MS
Roll suite implemented in X-Seed.
apparent Stokes shifts, taking into account the forbidden HOMO–
LUMO transition the genuine Stokes shifts are 28–45 nm (0.20–
0.31 eV, Table 1). Using time-dependent density functional theory
(TD-DFT) the calculated oscillator strengths for the HOMO–
LUMO transitions of 1[4–8] were rather low (f < 0.2) verifying the
forbidden nature of the HOMO–LUMO transition (Figure S79–
S83).
The unique photophysical properties of these CPP-type
macrocycles are assigned to their cyclic symmetric structure in
combination with the strain necessary to bend their otherwise
planar aromatic repeating units. We calculated the strain energy
of 1[4–8] using an homodesmotic approach and also assessed the
ring strain energy with StrainViz (Figure 3b,c).[55,56] The results of
these calculations generally follow the same and expected trend
for the series 1[5–8] except for the shortest, most strained tetramer
1[4], for which the homodesmotic equation calculates a higher
strain energy than the results obtained from the StrainViz analysis
(Figure 3b). Strain energies cannot be determined experimentally,
yet the calculated results allow for comparison within this set of
macrocycles.
energetic barrier to pass the gate of the cavity might be too high,
whereas for a large opening the effect of tight binding to the
confined space vanishes (see Supporting Information, Section
S7).[58–60] These considerations are experimentally supported by
our finding that 1[5] shows no binding with C60 using 1H NMR
spectroscopy (Figure S75), while the structurally similar [10]CPP
(with the same amount of phenylene units as 1[5]) shows very
strong binding towards fullerene (Ka = 1010 M–1).[61] Besides that
ratio, the cavity volume is the second crucial parameter, which we
visualized for each ring size using the MS Roll suite implemented
in X-Seed[62] (Figure 4, Section S7). Shape and size of this volume
preclude several potential guests according to earlier reports on
space filling.[63,64] While the ratio between the gate diameter and
the central diameter for [n]CPPs is 1, this ratio is with 0.64 and
0.67 considerably smaller for 1[4] and 1[5] (Table S8). To
investigate the influence on confinement we decided to first study
the guest properties of 1[5] since the average gate diameter at the
van der Waals surface of 1[4] was calculated to be 3.65 Å,
exhibiting a too small opening into the macrocycle’s cavity.
Host-in-host complexes are an intriguing starting point in the
construction of more complex superstructures.[65–67] A well-
studied example is the encapsulation of crown ethers or their
nitrogen containing equivalents into cages or capsular hosts.[68–72]
We selected crown ethers as guests because they are
conformationally flexible allowing them to pass the gate of the
macrocycle, and being readily available in various sizes. We first
studied the binding of several crown ether metal cation complexes
to 1[5] using UV/vis absorption spectroscopy in CHCl3 at 25 °C.
Addition of 12-crown-4⋅LiCl did not lead to a change in absorption
(Figure S61). In contrast, upon addition of 15-crown-5⋅Na(BF4) a
bathochromic shift combined with a narrowing of the absorption
band and multiple distinct isosbestic points were observed. The
new absorption maximum max of the complex 1[5]⋅⋅⋅[15-crown-
5⋅Na(BF4)] is red-shifted by 9 nm as compared to 1[5]. Isothermal
UV/vis absorption titration with addition of up to 54 equivalents of
15-crown-5⋅Na(BF4) and subsequent non-linear least-square
curve fitting afforded an association constant Ka = 8.0×104 M–1
(Figure 5a and Figure 5b, top). A perfect fit in size is further
suggested by DFT calculations (Figure S54 and Table S9). To the
best of our knowledge, this is the strongest binding observed for
a non-fullerene guest to a CPP or a CPP-related macrocycle.
To get more structural information on the binding we turned to
Table 1. Photophysical data of the series 1[4–8] in CHCl3 solution.
1[4]
374
468
0.28
1[5]
375
468
0.27
1[6]
371
448
0.31
1[7]
375
440
0.24
1[8]
378
435
0.20


max [nm]
emission [nm][a]
stokes shift [eV]
[a]Excitation at 375 nm
A great advantage of StrainViz is the visualization of the strain
energy at affected bonds, while classifying the strain energy into
bond-, angle-, and dihedral strain energy. For CPPs in general,
dihedral strain has the highest impact because an average
biphenyl angle of ~44° cannot be fulfilled between all Clar-sextet
units (Figure S84–S88).[57] Comparison of 1[4] to the equivalently
sized parent [8]CPP revealed an evenly distributed dihedral strain
energy on all eight biphenyl units for [8]CPP but a localized
dihedral strain energy over only four pyrene units in 1[4] (visualized
by red bonds, Figure 3c).
Confined spaces within the volumetric centers of 1[4–8 are
1
]
isothermal H NMR binding titration, but the necessity for higher
established by the radially converging ethylene groups into the
cavity gates of the macrocycles. A crucial parameter in this
concept is the ratio of the gate diameter formed by the ethylene
glycol groups to the cavity diameter in the center of the
macrocycle. If the gate diameter becomes very small the
concentrations than in the UV/vis experiments led to peak
broadening and precipitation upon addition of 15-crown-
5⋅Na(BF4) to a solution of 1[5] in CDCl3 (Figure S74). To
investigate the size-dependency of the binding, we studied the
next larger crown ether 18-crown-6 and its K+ complexes.
3
This article is protected by copyright. All rights reserved.

10.1002/anie.202102809
Angewandte Chemie International Edition
COMMUNICATION
Figure 5. a) Isothermal UV/vis binding titration of 1[5] (c0 = 3.8 M) upon addition of 15-crown-5⋅(NaBF4) at 25 °C in CHCl3. b) Differences in absorption in relation
to the guest concentration and curve-fitting to 1:1 isotherms (solid line). c) Isothermal UV/vis binding titration of 1[5] (c0 = 3.8 M) upon addition of 18-crown-6⋅K(BF4)
at 25 °C in CHCl3. d) Single-crystal X-ray structure of 1[5]⋅⋅⋅[18-crown-6⋅K(BF4)], H-atoms and solvent molecules are omitted for clarity, thermal ellipsoids shown at
50% probability, the structure on the right shows the conformational distortion of the 18-crown-6 ether.[77] e) top and side view on X-ray structure of 1[5]⋅⋅⋅[18-crown-
6⋅K(BF4)], where 1[5] is shown as sticks, 18-crown-6⋅K+ as van der Waals spheres, and the green surface represents the calculated cavity volume.
Isothermal UV/vis absorption titration upon addition of 18-crown-
6⋅K(BF4) (Figure 5c) gave a bathochromic shift of 5 nm for max
ethylene glycol unit twisted out-of-plane. The energetic penalty of
this bent conformation compared to its optimized planar
conformation was calculated to be 2.0 kcal mol–1 (DFT:B3LYP-
D3/QZVP in vacuum, Figure S45), well compensated by a non-
covalent interaction free enthalpy. Measuring the distance
between centroids of the phenyl subunits of 1[5] and the C-atoms
of the crown ether shows ten close contacts (3.5–4.0 Å) assigned
to C–H⋅⋅⋅interactions (Figure S43). Several further C–H⋅⋅⋅O
hydrogen bonds were determined between the strongly polarized
C–H groups of the crown ether as hydrogen bond donors and the
oxygens of the ethylene glycol groups of 1[5] acting as hydrogen
bond acceptors (Figure S45). The crystal structure shows a
tubular packing of 1[5], where the void space is filled with 18-
,
accompanied with a narrowing of the absorption, and several
distinct isosbestic points. Non-linear least-square curve fitting of
the absorption titration data afforded an association constant of
Ka = 1.2×104 M–1 (Figure 5b, bottom). This only slightly lower
Ka value compared to 15-crown-5⋅Na+ with 1[5] results from the
conformational flexibility of crown ethers. 18-Crown-6 can adopt
to the rigid host cavity by bending out one ethylene glycol unit, as
confirmed by X-ray crystallography (see below). In contrast, the
equally-sized but unconfined parent [10]CPP shows significantly
smaller binding constants of Ka = 103 M–1 and Ka = 24 M–1 for 15-
crown-5⋅Na(BF4) and 18-crown-6⋅K(BF4), respectively (25 °C,
CHCl3, Figure S70–S73). To complete the series, we investigated
the binding of the larger dibenzo-18-crown-6 — a guest even too
large to be included inside 1[7] — and we observed no binding
event (neither for 1[5] nor for 1[7], see Figure S59 and Figure S69,
respectiveley).
Investigating the host abilities of 1[6] towards crown ethers, no
pronounced binding was observed for the addition of neither 15-
crown-5⋅Na(BF4) (Ka = 28 M–1) nor 18-crown-6⋅K(BF4) (Ka too
weak to be detected, Figure S66–S68). We assign this result to
the drastic increase of the cavity volume by 23% from 1[5] to 1[6]
with the latter therefore requiring much larger guest for
reasonable strong binding. Further, no binding event could be
determined for 1[4] with the smallest crown ether 12-crown-4⋅LiCl,
which we assign to the already mentioned very small gate
opening, presumably requiring much higher energies to overcome
this barrier (Figure S56).
-
crown-6⋅K+ and the BF4 anion. These columnar stacks form a
hexagonal circle-packing motif (Figure S42).[73,74]
In summary, we successfully synthesized a series of five
[n]cyclo-2,7-(4,5,9,10-tetrahydro)pyrenylenes
1[4–8]
carrying
ethylene glycol groups at the outer rim to create a confined space
in the center of the macrocycles. The effect of confinement was
demonstrated by a significantly weaker binding of 15-crown-
5⋅Na(BF4) in [10]CPP or 18-crown-6⋅K(BF4) in [10]CPP. We
assign the improved binding to the confined space of 1[5] and the
additional hydrogen bond acceptors created by the introduction of
the dipolar ethylene glycol groups to form a cooperative
interaction network.[75] The observed association constant of 15-
crown-5⋅Na(BF4) to 1[5] is the largest of a non-fullerene guest to
a CPP-type macrocycle, thereby illustrating the potential of our
reported extension strategy to develop these highly fluorescent
and shape persistent macrocycles into
a new class of
Crystals suitable for synchrotron-based X-ray crystallography
were obtained for the complex 1[5]⋅⋅⋅[18-crown-6⋅K(BF4)] (Figure
5d). The cationic 18-crown-6⋅K+ is located in the center of the
cavity of 1[5] and the ethylene glycol groups of 1[5] embrace the
guest complex as a secondary coordination sphere.[72] 18-crown-
6⋅K+ is bound in an unexpected non-planar conformation with one
supramolecular hosts beyond fullerene guests.[61,76]
4
This article is protected by copyright. All rights reserved.

10.1002/anie.202102809
Angewandte Chemie International Edition
COMMUNICATION
Acknowledgements
[26] Y. Xu, R. Kaur, B. Wang, M. B. Minameyer, S. Gsänger, B. Meyer,
T. Drewello, D. M. Guldi, M. von Delius, J. Am. Chem. Soc. 2018,
140, 13413–13420.
We thank André Dallmann for assistance with the NMR
experiments, Christian Feiler and Manfred Weiss for assistance
at the beamline sector MX14.2 at BESSY-II, Hanna Arndt for
upscaling of the target compounds, Sebastian Pallasch for
suggestions on the selection of guests, Josefine Sprachmann for
valuable comments on the manuscript, Beatrice Cula and
Charlotte Stern (Northwestern) for crystallographic advice, and
Oskar Knittelfelder for measurement of HR-ESI-MS. N.G. was
supported by a doctoral fellowship of the Fonds der Chemischen
Industrie (FCI) and O.D. thanks the FCI for a generous Liebig
scholarship. We are grateful to Stefan Hecht for his continuous
support.
[27] S. Adachi, M. Shibasaki, N. Kumagai, Nat. Commun. 2019, 10,
3820.
[28] C. D. Gutsche, Acc. Chem. Res. 1983, 16, 161–170.
[29] A. G. S. Hogberg, J. Org. Chem. 1980, 45, 4498–4500.
[30] P. Timmerman, W. Verboom, D. N. Reinhoudt, Tetrahedron 1996,
52, 2663–2704.
[31] W. A. Freeman, W. L. Mock, N. Y. Shih, J. Am. Chem. Soc. 1981,
103, 7367–7368.
[32] B. M. White, Y. Zhao, T. E. Kawashima, B. P. Branchaud, M. D.
Pluth, R. Jasti, ACS Cent. Sci. 2018, 4, 1173–1178.
[33] T. A. Schaub, E. A. Prantl, J. Kohn, M. Bursch, C. R. Marshall, E.
J. Leonhardt, T. C. Lovell, L. N. Zakharov, C. K. Brozek, S. R.
Waldvogel, S. Grimme, R. Jasti, J. Am. Chem. Soc. 2020, 142,
8763–8775.
[34] T. Iwamoto, E. Kayahara, N. Yasuda, T. Suzuki, S. Yamago, Angew.
Chem. Int. Ed. 2014, 53, 6430–6434; Angew. Chem. 2014, 126,
6548–6552.
[35] A. Mateo-Alonso, Chem. Soc. Rev. 2014, 43, 6311–6324.
[36] J. Hu, D. Zhang, F. W. Harris, J. Org. Chem. 2005, 70, 707–708.
[37] B. L. Hu, K. Zhang, C. An, D. Schollmeyer, W. Pisula, M.
Baumgarten, Angew. Chem. Int. Ed. 2018, 57, 12375–12379;
Angew. Chem. 2018, 130, 12555–12559.
[38] N. Wang, X. Bao, Y. Yan, D. Ouyang, M. Sun, V. A. L. Roy, C. S.
Lee, R. Yang, J. Polym. Sci. Part A Polym. Chem. 2014, 52, 3198–
3204.
[39] During the preparation of this work, the borylation of ethylene
gylcol-protected pyrenetetrone was reported under similar reaction
conditions, see: J. Merz, M. Dietz, Y. Vonhausen, F. Wöber, A.
Friedrich, D. Sieh, I. Krummenacher, H. Braunschweig, M. Moos,
M. Holzapfel, C. Lambert, T. B. Marder, Chem. Eur. J. 2020, 26,
438–453.
Keywords: Cycloparaphenylenes • Host–guest systems •
Macrocycles • Molecular recognition • Supramolecular chemistry
[1]
[2]
[3]
[4]
[5]
P. S. Bols, H. L. Anderson, Acc. Chem. Res. 2018, 51, 2083–
2092.
M. Ball, B. Zhang, Y. Zhong, B. Fowler, S. Xiao, F. Ng, M.
Steigerwald, C. Nuckolls, Acc. Chem. Res. 2019, 52, 1068–1078.
M. Iyoda, J. Yamakawa, M. J. Rahman, Angew. Chem. Int. Ed.
2011, 50, 10522–10553; Angew. Chem. 2011, 123, 10708–10740.
Y. Segawa, A. Fukazawa, S. Matsuura, H. Omachi, S. Yamaguchi,
S. Irle, K. Itami, Org. Biomol. Chem. 2012, 10, 5979–5984.
S. Yamago, E. Kayahara, T. Iwamoto, Chem. Rec. 2014, 14, 84–
100.
[40] G. Fuhrmann, T. Debaerdemaeker, P. Bäuerle, Chem. Commun.
2003, 3, 948–949.
[41] S. Hitosugi, W. Nakanishi, T. Yamasaki, H. Isobe, Nat. Commun.
2011, 2, 492–495.
[6]
[7]
E. R. Darzi, R. Jasti, Chem. Soc. Rev. 2015, 44, 6401–6410.
M. Hermann, D. Wassy, B. Esser, Angew. Chem. Int. Ed. 2020,
DOI 10.1002/anie.202007024; Angew. Chem. 2020, DOI
10.1002/ange.202007024.
[42] Z. Sun, T. Mio, K. Ikemoto, S. Sato, H. Isobe, J. Org. Chem. 2019,
[8]
[9]
R. Jasti, J. Bhattacharjee, J. B. Neaton, C. R. Bertozzi, J. Am.
Chem. Soc. 2008, 130, 17646–17647.
N. Hayase, Y. Miyauchi, Y. Aida, H. Sugiyama, H. Uekusa, Y.
Shibata, K. Tanaka, Org. Lett. 2017, 19, 2993–2996.
84, 3500–3507.
[43] L. Sicard, F. Lucas, O. Jeannin, P. A. Bouit, J. Rault-Berthelot, C.
Quinton, C. Poriel, Angew. Chem. Int. Ed. 2020, 59, 11066–11072;
Angew. Chem. 2020, 132, 11159–11165.
[10] H. Takaba, H. Omachi, Y. Yamamoto, J. Bouffard, K. Itami, Angew.
Chem. Int. Ed. 2009, 48, 6112–6116; Angew. Chem. 2009, 121,
6228–6232.
[11] S. Yamago, Y. Watanabe, T. Iwamoto, Angew. Chem. Int. Ed.
2010, 49, 757–759; Angew. Chem. 2010, 122, 769–771.
[12] Y. Tsuchido, R. Abe, T. Ide, K. Osakada, Angew. Chem. Int. Ed.
2020, 59, 22928–22932; Angew. Chem. 2020, 132, 23128–23132.
[13] Y. Xu, S. Gsänger, M. B. Minameyer, I. Imaz, D. Maspoch, O.
Shyshov, F. Schwer, X. Ribas, T. Drewello, B. Meyer, M. von
Delius, J. Am. Chem. Soc. 2019, 141, 18500–18507.
[44] H. Jia, G. Zhuang, Q. Huang, J. Wang, Y. Wu, S. Cui, S. Yang, P.
Du, Chem. Eur. J. 2020, 26, 2159-2163.
[45] H. Jia, Y. Gao, Q. Huang, S. Cui, P. Du, Chem. Commun. 2018,
54, 988–991.
[46] H. W. Jiang, T. Tanaka, T. Kim, Y. M. Sung, H. Mori, D. Kim, A.
Osuka, Angew. Chem. Int. Ed. 2015, 54, 15197–15201; Angew.
Chem. 2015, 127, 15412–15416.
[47] E. Kayahara, T. Hayashi, K. Takeuchi, F. Ozawa, K. Ashida, S.
Ogoshi, S. Yamago, Angew. Chem. Int. Ed. 2018, 57, 11418–
11421; Angew. Chem. 2018, 130, 11588–11591.
[48] Y. Yoshigoe, Y. Suzaki, K. Osakada, Chem. Lett. 2014, 43, 1337–
1339.
[49] C. Eaborn, K. J. Odell, A. Pidcock, J. Chem. Soc., Dalt. Trans.
1978, 357–368.
[50] P. Neuhaus, A. Cnossen, J. Q. Gong, L. M. Herz, H. L. Anderson,
Angew. Chem. Int. Ed. 2015, 54, 7344–7348; Angew. Chem. 2015,
127, 7452–7456.
[51] Y. Zhou, K. Jie, R. Zhao, F. Huang, Adv. Mater. 2020, 32, 1–30.
[52] J. B. Lin, E. R. Darzi, R. Jasti, I. Yavuz, K. N. Houk, J. Am. Chem.
Soc. 2019, 141, 952–960.
[53] M. Fujitsuka, D. W. Cho, T. Iwamoto, S. Yamago, T. Majima, Phys.
Chem. Chem. Phys. 2012, 14, 14585–14588.
[14] M. Ball, B. Fowler, P. Li, L. A. Joyce, F. Li, T. Liu, D. Paley, Y.
Zhong, H. Li, S. Xiao, F. Ng, M. L. Steigerwald, C. Nuckolls, J. Am.
Chem. Soc. 2015, 137, 9982–9987.
[15] T. Kuwabara, J. Orii, Y. Segawa, K. Itami, Angew. Chem. Int. Ed.
2015, 54, 9646–9649; Angew. Chem. 2015, 127, 9782–9785.
[16] E. R. Darzi, E. S. Hirst, C. D. Weber, L. N. Zakharov, M. C.
Lonergan, R. Jasti, ACS Cent. Sci. 2015, 1, 335–342.
[17] D. Wassy, M. Pfeifer, B. Esser, J. Org. Chem. 2020, 85, 34–43.
[18] E. Kayahara, T. Iwamoto, H. Takaya, T. Suzuki, M. Fujitsuka, T.
Majima, N. Yasuda, N. Matsuyama, S. Seki, S. Yamago, Nat.
Commun. 2013, 4, 2694.
[19] N. Hayase, J. Nogami, Y. Shibata, K. Tanaka, Angew. Chem. Int.
Ed. 2019, 58, 9439–9442; Angew. Chem. 2019, 131, 9539–9542.
[20] S. Cui, G. Zhuang, D. Lu, Q. Huang, H. Jia, Y. Wang, S. Yang, P.
Du, Angew. Chem. Int. Ed. 2018, 57, 9330–9335; Angew. Chem.
2018, 130, 9474–9479.
[21] R. Frydrych, T. Lis, W. Bury, J. Cybińska, M. Stȩpień, J. Am.
Chem. Soc. 2020, 142, 15604–15613.
[22] Y. Xu, M. von Delius, Angew. Chem. Int. Ed. 2020, 59, 559–573;
Angew. Chem. 2020, 132, 567–582.
[23] N. Ozaki, H. Sakamoto, T. Nishihara, T. Fujimori, Y. Hijikata, R.
Kimura, S. Irle, K. Itami, Angew. Chem. Int. Ed. 2017, 56, 11196–
11202; Angew. Chem. 2017, 129, 11348–11354.
[24] T. Matsuno, M. Fujita, K. Fukunaga, S. Sato, H. Isobe, Nat.
Commun. 2018, 9, 3779.
[54] T. Iwamoto, Y. Watanabe, Y. Sakamoto, T. Suzuki, S. Yamago, J.
Am. Chem. Soc. 2011, 133, 8354–8361.
[55] S. E. Wheeler, K. N. Houk, P. v. R. Schleyer, W. D. Allen, J. Am.
Chem. Soc. 2009, 131, 2547–2560.
[56] C. E. Colwell, T. W. Price, T. Stauch, R. Jasti, Chem. Sci. 2020,
11, 3923–3930.
[57] A. Almenningen, O. Bastiansen, L. Fernholt, B. N. Cyvin, S. J.
Cyvin, S. Samdal, J. Mol. Struct. 1985, 128, 59–76.
[58] V. Maslak, Z. Yan, S. Xia, J. Gallucci, C. M. Hadad, J. D. Badjić, J.
Am. Chem. Soc. 2006, 128, 5887–5894.
[59] K. Hermann, Y. Ruan, A. M. Hardin, C. M. Hadad, J. D. Badjić,
Chem. Soc. Rev. 2015, 44, 500–514.
[60] K. N. Houk, K. Nakamura, C. Sheu, A. E. Keating, Science 1996,
273, 627–629.
[61] T. Iwamoto, Y. Watanabe, T. Sadahiro, T. Haino, S. Yamago,
[25] P. Della Sala, C. Talotta, T. Caruso, M. De Rosa, A. Soriente, P.
Neri, C. Gaeta, J. Org. Chem. 2017, 82, 9885–9889.
5
This article is protected by copyright. All rights reserved.

10.1002/anie.202102809
Angewandte Chemie International Edition
COMMUNICATION
Angew. Chem. Int. Ed. 2011, 50, 8342–8344; Angew. Chem. 2011,
123, 8492–8494.
[62] L. J. Barbour, J. Appl. Crystallogr. 2020, 53, 1141–1146.
[63] D. P. van Heerden, L. J. Barbour, Chem. Soc. Rev. 2021, 50, 735–
749.
[64] S. Mecozzi, J. Rebek, Chem. Eur. J. 1998, 4, 1016–1022.
[65] D. Zhang, T. K. Ronson, J. L. Greenfield, T. Brotin, P. Berthault, E.
Leónce, J. L. Zhu, L. Xu, J. R. Nitschke, J. Am. Chem. Soc. 2020,
141, 8339–8345.
[66] S. A. L. Rousseaux, J. Q. Gong, R. Haver, B. Odell, T. D. W.
Claridge, L. M. Herz, H. L. Anderson, J. Am. Chem. Soc. 2015,
137, 12713–12718.
[67] H. Wu, Y. Wang, L. O. Jones, W. Liu, B. Song, Y. Cui, K. Cai, L.
Zhang, D. Shen, X. Y. Chen, Y. Jiao, C. L. Stern, X. Li, G. C.
Schatz, J. F. Stoddart, J. Am. Chem. Soc. 2020, 142, 16849–
16860.
[68] F. Vögtle, W. M. Müller, Angew. Chem. Int. Ed. 1979, 18, 623–624;
Angew. Chem. 1979, 91, 676–677.
[69] S. Y. Kim, I. S. Jung, E. Lee, J. Kim, S. Sakamoto, K. Yamaguchi,
K. Kim, Angew. Chem. Int. Ed. 2001, 40, 2119–2121; Angew. Chem.
2001, 113, 2177–2179.
[70] S. J. Dalgarno, J. L. Atwood, C. L. Raston, Chem. Commun. 2006,
4567–4574.
[71] T. N. Parac, M. Scherer, K. N. Raymond, Angew. Chem. Int. Ed.
2000, 39, 1239–1242; Angew. Chem. 2000, 112, 1288–1291.
[72] A. Lützen, A. R. Renslo, C. A. Schalley, B. M. O’Leary, J. Rebek,
J. Am. Chem. Soc. 1999, 121, 7455–7456.
[73] A. Bezdek, W. Kuperberg, Mathematika 1990, 37, 74–80.
[74] J. M. Van Raden, E. J. Leonhardt, L. N. Zakharov, A. Pérez-
Guardiola, A. J. Pérez-Jiménez, C. R. Marshall, C. K. Brozek, J. C.
Sancho-García, R. Jasti, J. Org. Chem. 2020, 85, 129–141.
[75] B. Kuhn, J. E. Fuchs, M. Reutlinger, M. Stahl, N. R. Taylor, J.
Chem. Inf. Model. 2011, 51, 3180–3198.
[76] S. Hitosugi, W. Nakanishi, T. Yamasaki, H. Isobe, Org. Lett. 2013,
15, 3199–3201.
[77] CCDC-1940871 (5), CCDC-2049516 (4), CCDC-2049515 (3),
CCDC-2050148 (1[4]), CCDC-1876252 (1[6]), CCDC-2049763
–
(1[5]⋅⋅⋅18-crown-6⋅K+ (BF4 )), contain the supplementary
crystallographic data for this paper, including structure factors and
refinement instructions. These data can be obtained free of charge
from the joint Cambridge Crystallographic Data Centre and
Fachinformationszentrum Karlsruhe Access Structures service
online access via www.ccdc.cam.ac.uk/structures.
6
This article is protected by copyright. All rights reserved.

10.1002/anie.202102809
Angewandte Chemie International Edition
COMMUNICATION
7
This article is protected by copyright. All rights reserved.