Bandgap Engineering in π-Extended Pyrroles. A Modular Approach to Electron-Deficient Chromophores with Multi-Redox Activity

Article abstract of DOI:10.1021/jacs.6b07826

A family of bandgap-tunable pyrroles structurally related to rylene dyes was computationally designed and prepared using robust, easily scalable chemistry. These pyrroles show highly variable fluorescence properties and can be used as building blocks for the synthesis of electron-deficient oligopyrroles. The latter application is demonstrated through the development of π-extended porphyrins containing naphthalenediamide or naphthalenediimide units. These new macrocycles exhibit simultaneously tunable visible and near-IR absorptions, an ability to accept up to 8 electrons via electrochemical reduction, and high internal molecular free volumes. When chemically reduced under inert conditions, the most electron-deficient of these macrocycles revealed reversible formation of eight charged states, characterized by remarkably red-shifted optical absorptions, extending beyond 2200 nm. Such features make these oligopyrroles of interest as functional chromophores, charge-storage materials, and tectons for crystal engineering.

Full text of DOI:10.1021/jacs.6b07826

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Article
Bandgap Engineering in #-Extended Pyrroles. A Modular Approach
to Electron-Deficient Chromophores with Multi-Redox Activity
Halina Zhylitskaya, Joanna Cybinska, Piotr Chmielewski, Tadeusz Lis, and Marcin St#pie#
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.6b07826 • Publication Date (Web): 17 Aug 2016
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Bandgap Engineering in π-Extended Pyrroles. A Modular Approach
to Electron-Deficient Chromophores with Multi-Redox Activity
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Halina Zhylitskaya,† Joanna Cybińska,†‡ Piotr Chmielewski,† Tadeusz Lis,† and Marcin Stępień†*
† Wydział Chemii, Uniwersytet Wrocławski, ul. F. Joliot-Curie 14, 50-383 Wrocław, Poland
‡ Wrocławskie Centrum Badań EIT+, ul. Stabłowicka 147, 54-066 Wrocław, Poland
ABSTRACT: A family of bandgap-tunable pyrroles structurally related to rylene dyes was computationally designed and prepared
using robust, easily scalable chemistry. These pyrroles show highly variable fluorescence properties and can be used as building
blocks for the synthesis of electron-deficient oligopyrroles. The latter application is demonstrated through the development of π-
extended porphyrins containing naphthalenediamide or naphthalenediimide units. These new macrocycles exhibit simultaneously
tunable visible and near-IR absorptions, an ability to accept up to 8 electrons via electrochemical reduction, and high internal
molecular free volumes. When chemically reduced under inert conditions, the most electron-deficient of these macrocycles
revealed reversible formation of eight charged states, characterized by remarkably red-shifted optical absorptions, extending
beyond 2200 nm. Such features make these oligopyrroles of interest as functional chromophores, charge-storage materials, and
tectons for crystal engineering.
merging of existing electron-deficient and electron-rich
motifs.
INTRODUCTION
The synthetic chemistry of large polycyclic heteroaromatic
molecules (PHAs) has recently become an area of intense
investigation, because of the relevance of such systems as
heteroatom-doped analogues of nanographenes and graphene
nanoribbons.1,2 The prospective use of these molecules in
organic electronics requires precise control over their π-
conjugation, notably their frontier orbital energies and
electronic bandgaps. The synthesis of extended PHA systems
can in principle be simplified by employing a modular
approach, in which suitably designed building blocks
(monomers) are covalently assembled into larger fused
structures. For maximum design flexibility, bandgap
engineering should be performed on the building block level.
However, such an approach requires not only efficient
strategies of bandgap tuning but also a good understanding of
the relationship between the electronic structure of the
monomer and the properties of its oligomeric derivatives.
A simple and potentially productive design of such a hybrid
structure, consisting of naphthalenemonoimide (NMI, red)
and pyrrole (blue), is proposed in Figure 1. NMI is the key
constituent
of
perylenediimide
(PDI)26–28
and
naphthalenediimide (NDI)29 dyes, and is known to offer
excellent chemical stability and diverse derivatization options,
usually based acyl chemistry, heterocyclic annulation
reactions,30 and lateral ring fusion.31 Structural modifications
can be used to change the electron-withdrawing character of
the naphthalene fragment, which thus can serve as a tunable
acceptor unit.32,33 Consequently, the NMI-based and related
chromophores can be tailored for use in various fields of
application, e.g. as n-channel OFETs,34 or functional cavities.35
Because the bandgap changes in such hybrid monomers are
expected to be amplified upon oligomerization, the resulting
pyrroles are of immediate interest as building blocks for small-
molecule dyes, such as dipyrrins36,37 or α-linked
oligopyrroles,38,39 as well as for pyrrole-based macrocycles,40
nanographenoids,41–44 and polymers.22,45 The synthetic
approach relying on tunable pyrrole monomers can thus be
envisaged to complement the existing routes to directly fused
rylene–oligopyrrole hybrids.46–48
Systematic tuning of optical bandgaps3 can be achieved by
homologation (oligomerization) of linear π-conjugated
motifs,4 such as oligophenyls,5,6 rylenes,7–9 oligoporphyrins,10,11
or BODIPY12 derivatives, although in general, the bandgap
narrowing effect weakens with the increasing oligomer length.
A formally related strategy involves ring expansion of π-
conjugated macrocycles,13,14 but its predictability is limited by
the complex conformational behavior of large rings.15
A
complementary approach relies on combining donor and
acceptor (D–A) moieties, with diverse recent applications in
small-molecule16–21 and polymer chemistry.22–25 The D–A
method is particularly suitable for the development of tunable
building blocks, which can be constructed by judicious
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Because of the favorable combination of chemical stability and
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4
reactivity, these pyrroles are useful as covalent building
blocks. This use is demonstrated here by the synthesis of π-
extended porphyrin derivatives characterized by large
curvatures and a remarkable multi-redox behavior.
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RESULTS AND DISCUSSION
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Pyrroles: Design and Synthesis. The design of the pyrrole
library shown in Chart 1 was guided by DFT calculations,
which provided theoretical estimates of HOMO–LUMO gaps
(HLGs), from either Kohn–Sham (KS) orbital energies or TD-
DFT excited-state calculations. It was found that, starting
from compound 2, the HLG could be progressively reduced by
structural elaboration of the acceptor end of the fused pyrrole.
Switching off the acceptor functionality by reduction of the
amide groups was also considered (compound 1), and was
indeed predicted to result in a broadened HLG (3.81 eV),
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Figure 1. Design principle illustrated for the prototypic NMI–
pyrrole hybrid. FGI, functional group interconversion, SE(N)Ar
aromatic electrophilic (nucleophilic) substitution.
Chart 1. π-Extended Pyrrole Librarya
a Natural population (NPA) charges on the pyrrole rings, calculated Kohn–Sham HOMO, LUMO, and bandgap (HLG) energies,
TDA bandgaps (f > 0.05), and oscillator strengths, dipole moments; all values calculated at the PCM(DMSO)/B3LYP/6-31G(d,p)
level of theory. dipp = 2,6-di(isopropyl)phenyl.
Figure 2. Optical properties of pyrroles 1–9. (A) Absorption spectra (~0.1 mM, DMSO, 293 K). (B) Fluorescence emission spectra
(~5 μM, DMSO, 293 K). (C) Fluorescence solvatochromism of 4. Fluorescence quantum yields (ΦF, values in red) are given in %.
Here we show that by fusing pyrrole with electron-deficient
naphthalene derivatives, it is possible to create a family of
chromophores with tunable electronic characteristics.
comparable with those calculated for reported electron-rich
systems, the unsubstituted acenaphthopyrrole49–53 and its 2,5-
di-tert-butyl derivative54 (3.89 and 3.97 eV, respectively, at the
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same level of theory). In 2, the KS bandgap (3.70 eV) is
comparable with that predicted for 3,4-
The bandgap difference between the diamide 2 and the
diester 3 (λmaxabs of 377 and 393 nm, respectively, ΔE = 0.13 eV)
is quite significant, and an even larger difference is observed
between the emission maxima (0.39 eV). Inspection of the
ground-state geometries of 2 and 3 reveals a difference of
torsional angles of the carbonyl groups relative to the
aromatic core. In the solid-state structure of 2 (Figures S21,
S24), the amide groups take an antiparallel orientation, with
the CCCO torsions relative to the naphthalene of ca. 52–53°. A
slightly larger value (57.5°) was found in the DFT geometry of
2. In the DFT geometry of 3, the corresponding torsion is
reduced to 36.3°, providing better conjugation of the ester
substituents with the aromatic rings, and a reduction of the
observed bandgap. The difference in CCCO torsions between
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dichloroacenaphthopyrrole53,55 (3.64 eV). In pyrroles 2–5, the
reduction of the bandgap is achieved principally by the
increasing electron-withdrawing effect of the functional
groups, which is demonstrated by the progressive decrease of
the KS HOMO and LUMO energies and by the increase of the
partial charge residing on the pyrrole ring (Chart 1, Figure
S37). In the small-bandgap derivatives 6–9, the pyrrole partial
charge and the LUMO energy vary over a narrow range and
the decrease in HLG is caused by lifting of the HOMO levels,
which can be attributed to the extension of the π system.
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The preparative work was commenced with the synthesis of
the diamide pyrrole 2 (Chart 1), which was obtained from
acenaphthene in 6 steps (Supporting Information). The
procedure, relying on the sulfone-Zard–Barton reaction56 as
the key step, is easily scalable, yielding multigram quantities
of the product. The electron-withdrawing character of the
amide groups in 2 provides sufficient stability to the fused
pyrrole ring to permit chemoselective functionalization of the
acceptor end of the molecule under a range of reaction
conditions. Thus, by using straightforward transformations, a
library of diversely functionalized pyrrole derivatives could be
rapidly developed from 2 (Chart 1). Diamine 1, imide 4, and
anhydride 5 were obtained respectively via LAH reduction
(71%) and acid-catalyzed imidation (67%), and cyclization
(82%). DBU-catalyzed MeI/MeOH cleavage of 5 produced
diester 3 (82%). When condensed with appropriate aromatic
diamines, 5 furnished imidazoles 6 (86%) and 7 (52%) and the
fused pyrimidine 9 (79%). Finally, compound 8 was obtained
in two steps57 from 5, quinaldine and boron trifluoride (42%
overall yield). With the exception of 8, which is prone to
hydrolysis, the pyrroles show good to excellent chemical and
photochemical stability. In particular, dilute solutions of 4–7
and 9 (e.g., 0.1 mM in DMSO) can be stored for weeks under
ambient conditions with no significant decomposition.
2 and
3 apparently originates from the larger steric
requirements of the NMe2 group relative to OMe. The
different alignment of amide groups in 2 may be further
stabilized by a tandem n→π* interaction, similar to those
observed in peptide chains.59,60 This conjecture finds support
in the increased pyramidalization (Δ = 0.034 Å) of carbonyl
carbons in 2 relative to those in 3 (Δ = 0.026 Å, Figure S24).
TD-DFT calculations predicted a significant reorganization of
substituents in the S1 excited states of 2 and 3. The S1 geometry
of 2 is asymmetric (CCCO torsions of 61° and 37°), with a single
enhanced n→π* interaction (Δ = 0.052 Å), whereas in the S1
state of 3, the ester groups take a more coplanar position, with
the CCCO torsions of 26°.
The conjugation is further improved upon planarization
and subsequent π extension of the chromophore in derivatives
4–9. The progression of red shifts in absorption and
fluorescence spectra is however non-uniform, because several
electronic effects contribute to the overall effect. For instance,
in the imidazoles 6 and 7, TD-DFT calculations show that the
lowest-energy absorption band consists of two transitions
(Figures S33, S34), each of which independently varies in its
energy and oscillator strength in these two systems. Thus,
even though λmaxabs is larger for 7, the actual bandgap is nearly
identical in both derivatives, and the emission maximum of 6
is in fact slightly red shifted relative to that of 7.
Pyrroles: Structure and Optical Properties. Absorption
measurements performed for 1–9 confirmed the qualitative
validity of DFT calculations. The observed bathochromic shift
of the lowest-energy absorption in the pyrroles (Figure 2A)
was in agreement with the TD-DFT predicted bandgap
variation (Chart 1), leading to a color progression from
colorless through red-brown. Pyrroles 1–8 showed a weak-to-
moderate fluorescence emission in DMSO solutions (ΦF
<
20%, Figure 2B), whose color varied from blue to red, tailing
into the near-IR range for 6–8. The fluorescence red shifts
were found to correlate better with absorption onsets rather
than with positions of absorption maxima. For 9, weak
fluorescence emission with λmaxem ≈ 630 nm was recorded in a
DMSO solution (Figure S17). The fluorescence quantum yield
of 4 did not improve upon N-substitution (4', R = CH2CHEt2,
11%), indicating that NH hydrogen bonding does not
significantly contribute to nonradiative deactivation in these
systems. The π-extended pyrroles show noticeable
solvatochromism, which we investigated in detail for the dipp-
imide 4 (Figure 2C). For this system, it was found that on going
Figure 3. Crystal packing of 5 and intermolecular interactions
observed in the solid state.
A consequence of the D–A design is the presence of large
dipole moments in the molecules of pyrroles 2–9 (Chart 1),
with a particularly large value calculated for the anhydride 5
(15.7 D). This feature is apparently responsible for the
formation of antiparallel stacks in the solid-state structure of
5 (Figure 3). The resulting compensation of adjacent dipoles is
em
from toluene to methanol, λmax increases from 522 to 622
nm. As frequently observed in D–A fluorophores,58 the
strongest emission was observed in the least polar solvents (ΦF
≈ 23% in in toluene), and the quantum yields decreased
considerably with increasing solvent polarity.
a
promising characteristic for applications in organic
photovoltaic and transistor devices.61–64 These stacks are only
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slightly slipped (slip angle of 23°), and feature a small
Zn(OAc)2. As a result, the expected 11-Zn complex was
obtained in an overall 87% yield. This procedure not only
offers more efficient alternative to direct pyrrole
condensation, but also provides a general and concise route to
variously N-substituted NMI-fused porphyrins.
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interplanar distance of 3.35 Å between consecutive molecules.
The full coplanarity of all molecules in the crystal of 5 (i.e. the
absence of herringbone packing) is expected to enable
anisotropic electron transport along the π-stacking
direction.65 An additional enhancement of electron-transport
properties may be provided by NH···O hydrogen bonds,66,67
which form between adjacent stacks in one direction.
a
Chart 2. π-Extended Electron-Deficient Porphyrins
Porphyrins: Synthesis and Structure. To demonstrate
the anticipated effect of pyrrole bandgap tuning on the
electronic structure of higher-order systems, we chose to
synthesize π-extended porphyrins 10-M and 11-M (Chart 2, M
= 2H, Zn), bearing respectively naphthalene diamide (NDA)
and naphthalene monoimide (NMI) units. These systems were
envisaged as particularly attractive targets because of the
inherently large red shifts observed for their electron-rich
analogues,49–53,55 and the soft character of the constituent
chromophores,68 which makes them susceptible to bandgap
engineering.52 meso-Aryl substitution was chosen with the
expectation that the resulting macrocycles will be non-planar
in analogy to meso-aryl acenaphthoporphyrins,50,52 thus
alleviating the solubility problems characteristic of their
planar, meso-free congeners.50
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The 1H NMR spectrum of 11-H2 revealed the presence of two
nonequivalent sets of isopropyl substituents, consistent with
the effective D2d point symmetry and saddle-shaped curvature
of the macrocycle. At 370 K, chemical exchange between the
two iPr groups was observed (ROESY, DMSO-d6, 600 MHz),
indicative of slow macrocyclic inversion. Solid-state (X-ray)
and gas-phase (DFT) geometries of 11-H2 showed that the
The NDA-fused macrocycle was synthesized from the
corresponding monopyrrole
2 under modified Lindsey
conditions,69 and isolated as the trifluoroacetate salt [10-
H4][TFA]2 in a 42% yield. The efficiency of this condensation
Figure 4. Solid-state structures of 11-M. (A) Internal molecular free volume estimation in 11-H2. (B) Stacking along the c axis in
the I–4 phase of 11-H2. Each void is occupied by ca. 2 disordered CHCl3 molecules. Channel structures (procrystal electron density,
0.0003 au isosurface, solvent molecules removed for calculation) for the I–4 phase of 11-H2 (C, view along c) and C2/c phase of 11-
Zn (D, view along a). The interior of the channels is colored in gray.
reaction is particularly appreciable, given the electron-poor
nature of the monopyrrole. The porphyrin salt, which can be
made on a several hundred-milligram scale, was then
converted into the corresponding free base and zinc(II)
complex under standard conditions. The macrocyclization of
4 leading to the NMI system was not as efficient, providing
only a 18% yield of 11-H2. The latter observation prompted the
development of an indirect synthesis of the NMI target from
the more easily accessible NDA porphyrin. To this end, [10-
H4][TFA]2 was refluxed with concentrated hydrochloric acid
to hydrolyze the amide groups. The resulting poorly soluble
intermediate was investigated using MALDI and shown to
consist of the corresponding octacarboxylic acid and
anhydrides formed by its partial dehydration. This material
was directly condensed with dipp-NH2, and metalated with
molecule has a shape of a nanometer-sized tetrahedron,
slightly flattened along the effective S4 symmetry axis, with the
distances between imidic nitrogens of 16.0 and 18.6 Å (solid
state, 16.1 and 18.3 Å, DFT). The shape of the tetrahedron is
essentially unaltered in the crystal structure of 11-Zn; however,
the NMR data obtained for the latter complex indicate that
the barrier to inversion decreases upon metal binding. An
earlier analysis of conformational dynamics of related
acenaphthoporphyrins involved a mixture of meso-atropisomers and
was not fully conclusive.52
The 1H NMR spectrum of 10-H2 (CDCl3, 300 K) is
complicated by the partially restricted rotation of amide
substituents, which leads to the formation of atropisomers.
Fast rotation of amide groups relative to the aromatic core
could however be observed at 410 K in DMSO-d6 (600 MHz).
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Because no suitable spectroscopic probe is present in 10-H2,
the visible part of the absorption spectrum, is shifted from 583
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its dynamics of inversion could not be monitored using NMR.
However, the latter system is nevertheless expected to behave
similarly to its imide analogue. In CDCl3, the 1H NMR
spectrum of 10-Zn reveals similar atropisomerism but is
further complicated by aggregation, as judged by the
unusually upfield shifts of selected signals.70 The complexity
of the spectrum precluded a detailed structural analysis, but
we suppose that the formation of aggregates, which was not
observed for 11-Zn, is enhanced herein by intermolecular
coordination of amide substituents to Zn centers in 10-Zn.
to 632 nm (ΔE = 0.16 eV), producing a dramatic color change
(from violet to green). Thus, because of the unique position of
the Soret bands,68 the tuning of chromophore properties in 10-
Zn and 11-Zn takes place simultaneously in the visible and NIR
regimes. Both complexes showed weak fluorescence in the
near IR range (ΦF ≈ 1%; λmaxem = 806 and 893 nm for 10-Zn to
11-Zn, respectively). The red shifts of the optical spectrum
induced in11-Zn by NMI fusion are very large and comparable
with those previously achieved by meso-substitution and
metalation of tetraacenaphthoporphyrin.52 Since the latter
method of optical tuning is complementary to the present D–
A strategy, further reduction of bandgaps can be anticipated
when these two approaches are used in conjunction.
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The saddle-shaped distortion of the aromatic core in 11-H2
creates two shallow yet laterally extended cavities on the
opposite sides of the macrocyclic surface. A conservative
estimate of the internal molecular free volume (IMFV)71,72
yields a value of ca. 600 Å3 (Figure 4A). In contrast to
triptycene (IMFV ≈ 93 Å3), in which the voids are formed by
three non-conjugated benzene rings, the cavities in 11-H2 are
located within a contiguously conjugated π system that is
deformed by steric effects. Flanked by the bulky dipp groups,
the distorted core of 11-H2 does not support π-stacking in the
solid-state,
instead
promoting
the
formation
of
intermolecular voids, which can enclathrate solvent
molecules. In a tetragonal (I–4) crystal of 11-H2·xCHCl3 (x ≈ 6),
the saddles are stacked along the c axis (Figure 4B), with the
iPr groups resting on the naphthalene fragments of the
neighboring molecules. Each of the intervening cavities
tightly encapsulates an assembly of ca. two disordered
chloroform molecules (additional CHCl3 molecules are
present in between the stacks).
Figure 5. Electronic absorption spectra (~10 μM, colored
traces) and fluorescence emission spectra (~5 μM, black
traces) of 10-Zn and 11-Zn (toluene + 1% pyridine, 293 K).
Dispersion interactions involving the iPr groups are also
responsible for organizing the crystal packing in a monoclinic
(C2/c) polymorph, 11-M·xCH2Cl2·yC6H14 (x ≈ 2.25, y ≈ 5.75 for
M = Zn; low-quality isomorphous crystals of 11-H2 were also
obtained). The latter structure revealed a complex 3D system
of channels, enclathrating disordered solvent molecules.
These channels are permeable to spherical probes of up to 1.8
Å radius (Figure S27).73 Calculations using the procrystal
electron density method74 performed for the solvent-free
model of the C2/c phase showed that the voids occupy 31% of
the cell volume. In the less solvated I–4 phase of 11-H2, the
channels take up ca. 18% of the cell volume and have a
permeability limit at a probe radius of ~1.3 Å. In the absence
of strong intermolecular interactions, the crystals of 11-Zn
disintegrated rapidly on desolvation, and the remaining
material was found to be effectively amorphous by powder X-
ray diffraction. Nevertheless, the high solvation levels and
channeled structures observed in the solid state indicate that
with proper functionalization, such rigid non-planar
aromatics may be usable for building extrinsically porous non-
covalent frameworks.75–78
Porphyrins: Electronic Structure. The optical properties
of 10-M and 11-M confirm the expected reduction of the
electronic bandgap caused by fusion of electron deficient
moieties. In particular, the absorption spectra of 10-Zn and 11-
Zn show distinct red shifts relative to the spectrum of their
abs
naphthalene-unsubstituted analogue52 (λmax = 558 and 672
nm for the lowest energy Soret and Q band, respectively). On
going from 10-Zn to 11-Zn, the overall absorptivity increases,
and the lowest-energy Q band experiences a red shift from 775
to 838 nm (Figure 5), corresponding to an apparent bandgap
decrease of 0.12 eV. Likewise, the Soret band, which dominates
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The electron-withdrawing peripheries of 10-Zn and 11-Zn
V relative to Fc+/Fc81) is too high to provide full coverage of
the electrochemically determined reductions, the chemical
charging of 11-Zn can be assisted by the coordination of
sodium to the resulting anions.82
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provide considerable stabilization of multiply charged anions.
Using voltammetry, we were able to demonstrate six
reduction waves for 10-Zn, covering a range of potentials from
–1.37 to –2.72 V vs. Fc+/Fc. Remarkably, eight chemically
reversible reductions (–0.97 to –2.71 V) were recorded for the
more electron-deficient 11-Zn. The redox behavior of both
porphyrins could be semi-quantitatively reproduced in a
computational electrochemistry analysis, which gave roughly
linear relationships between DFT-estimated absolute
potentials and experimental values (Figure 6B). Our
electrochemical results stand in sharp contrast with the
behavior of zinc meso-tetratolylporphyrin, which can only
accept two electrons under conventional experimental
conditions,79 and required a potential of ca. –3.7 V vs. Fc+/Fc
to be charged to the hexaanion level.80 Importantly, the parent
monopyrrole (investigated in the N-substituted form 4',
Figure 6A) is also significantly more difficult to reduce than
11-Zn. These observations indicate that the multi-charging
capability only emerges from the combination of the two
structural motifs, as a key benefit of our modular design.
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The eightfold electrochemical reduction of 11-Zn is a unique
phenomenon, without a related precedent in the literature.
Recognizing the relevance of the above finding, we next
explored whether such highly charged species could also be
generated by chemical reduction. To this end, titration of 11-
Zn
with
sodium
anthracenide
was
followed
spectrophotometrically in THF under strictly oxygen- and
moisture-free conditions (Figure 7). The formation of eight
consecutive species was identified in the course of the
titration, but the individual forms were occasionally difficult
to discern in the absence of clear isosbestic points. The
analysis of the titration data was facilitated in a two-
dimensional representation (Figure 7, bottom), in which
specific absorption maxima could be more easily identified.
Qualitatively, the reactivity induced by anthracenide is
consistent with that observed electrochemically, and we
propose that the species obtained by chemical reduction may
indeed correspond to the [11-Zn]n– anions with n = 1 to 8.
While the reported potential of sodium anthracenide (ca. –2.5
Figure 6. (A) Differential pulse voltammograms for 10-Zn, 11-Zn, and 4' (THF, 0.1 M [NBu4][BF4], 293 K). Literature redox
potentials for zinc(II) tetratolylporphyrin, Zn(TTP), in DCM and NHMe2, have been re-referenced against the Fc+/Fc couple. (B)
Relationship between DFT-estimated absolute redox potentials for 10-Zn and 11'-Zn (SMD(THF)/M06-2X/cc-VTZ//B3LYP/6-
31G(d,p)) and experimental values determined for 10-Zn and 11-Zn, respectively. A weak chemically non-reversible wave at –2.95
V, observed for 10-Zn, which might correspond to the 7th reduction is included in the graph. (C) NPA charge distribution for
variously charged states of 10-Zn and 11'-Zn (M06-2X/cc-VTZ//B3LYP/6-31G(d,p)).
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an apparent decrease of macrocyclic aromaticity. The anions
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8
absorb light in an unusually broad range of wavelengths,
covering the UV, visible, and NIR regions, and the overall
absorptivity remains high at all reduction stages (εmax of
50000-100000 M–1 cm–1). When these orbitals are partly filled
upon reduction, the resulting electron configurations may
indeed be expected to produce small optical bandgaps. 11-Zn
can thus be regarded as a redox-switchable panchromatic
absorber with extended NIR activity. These optical features
can be tentatively linked to small energy differences between
the six lowest-lying virtual levels in the neutral 11-Zn, all of
which are characterized by considerable amplitudes on the
NMI units (Figure S38).
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Under completely inert conditions, the reduced forms of 11-
Zn are stable in solution. They are however immediately
decomposed to unidentified products when exposed to air,
and only [11-Zn]– could be transiently generated when traces
of oxygen were present in solution. Nevertheless, when the
presumed [11-Zn]8– was directly treated with excess I2 in THF,
ca. 90% of the initial 11-Zn could be recovered (estimated
spectrophotometrically). The latter experiment, which also
required strict exclusion of oxygen, clearly demonstrates that
the anthracenide-induced reduction of 11-Zn has a generally
reversible character.
Gas-phase geometries obtained for [10-Zn]n and [11'-Zn]n (n
= –8 to +4, R = H for 11') at the B3LYP/6-31G(d,p) level of theory
are only weakly dependent on the overall oxidation level,
although the saddle-like bending of the aromatic core
increases for the most highly charged cations and anions. At
this level of theory, di- and tetraanions of 10-Zn and 11'-Zn
yielded broken-symmetry wavefunctions with nonzero S2
values (Table S5), suggesting that a partial open-shell
character can be anticipated for these anions. KS bandgaps
calculated for cations and anions are considerably diminished
relative to those of the neutral 10-Zn and 11'-Zn, in line with
the results of reduction experiments presented above.
On the basis of simple π-electron count,15 one might expect
the even-electron [10-Zn]n and [11'-Zn]n species to alternately
exhibit macrocyclic aromaticity (n = +4, 0, –4, –8) and
antiaromaticity (n = +2, –2, –6). NICS(1) values calculated
above the C3N2Zn ring centers for [11'-Zn]n (even n, ring A in
Table S15) show that, in comparison with the neutral state (–
10.7 ppm, strongly diatropic), the internal porphyrin ring
currents are generally diminished upon charging (NICS(1) of
0.1 to –6.7 ppm at the C3N2Zn ring centers), with the exception
of the dication [11'-Zn]2+, which is predicted to be strongly
paratropic (18.2 ppm). Simultaneously, the six-membered
rings of naphthalene fragments retained negative values
across the entire range of explored oxidation levels (–5.1 to –
9.9 ppm). These results agree with the perceived loss of
macrocyclic aromaticity, inferred from the absorption spectra
of the anions.
The dependence of charge distribution in [10-Zn]n and [11'-
Zn]n on the oxidation level (n = –8 to +4) was explored by
means of natural population analysis (NPA, Figure 6C). On
going from [10-Zn]0 to [11'-Zn]0, the total NPA charge on the
Zn–porphine fragment increases from –0.27 to –0.20, in line
with the increasing electron-accepting character of the
peripheral units (NDA vs. NMI). It is however of interest that
the peripheral moieties in neutral zinc porphyrins bear a
positive charge, indicating a polarization reversal relative to
monopyrroles. Nevertheless, upon reduction, these peripheral
Figure 7. Titration of 11-Zn (0.025 mM in THF) with sodium
anthracenide. NIR absorptions in the 1100–2200 nm range
were recorded in a separate experiment. The bottom panel
shows the progress of titration as a 2D map, with a vertical
resolution of 78 addition steps. Diagnostic maxima in the 300–
1100 nm range, used for identification of consecutive species,
and the expected charges are indicated with purple arrows in
both panels. Additional maxima above 1100 nm are indicated
with gray arrows.
The absorption spectra of the [11-Zn]n– anions show
multiple broad bands of considerable intensity in the near
infrared range. With the exception of [11-Zn]8–, the
absorptions extend beyond 2200 nm, indicating a dramatic
reduction of the optical bandgaps relative to the neutral 11-Zn
(below 0.56 eV). The spectra do not have the typical
porphyrin-like appearance, with clearly defined Soret- and Q-
band regions. The π-electron conjugation in these anions is
thus considerably perturbed relative to the neutral state, with
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Page 8 of 11
fragments accept most of the incoming negative charge. The
layers in bulk heterojunction photovoltaics.105 In addition, the
high nonplanarity combined with uninterrupted
1
2
3
4
5
6
7
8
charge-storage capacity of the NMI units is higher in the initial
reduction steps (n = –1 to –4), but it levels off at 79% of the
total charge (over 6 charge units) in both systems for n = –8.
π
conjugation in these macrocycles may provide access to
extensively conjugated 3D systems, which, depending on the
specific design, can reveal either intrinsic or extrinsic porosity.
Most importantly, however, the structural paradigm
employed here for the development of porphyrins is likely to
be applicable to other classes of oligopyrroles. Efforts to
explore these possibilities in various pyrrole-containing
chromophores are currently underway.
Charging a contiguously π-conjugated moiety beyond the
tetraanion stage is generally difficult, especially in
unsubstituted hydrocarbons.83 Available data indicate that the
charging capacity of π systems does not increase linearly with
their size. Highest charge densities per non-H atom of −0.20
to −0.25 were reported for tetraanions of pyrene,84 perylene,84
9
acepleiadylene85
tetradehydro[18]annulene,86
and
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ASSOCIATED CONTENT
Supporting Information
corannulene,87–89 which typically benefit from aromatic
stabilization and countercation coordination (notably Li).
Peripheral imide groups assist in delocalization of negative
charge, and a heptaanion was electrochemically generated for
N-type nanoribbons containing 8 imide groups.90 The latter
design produced a much lower charge-per-atom density of
−0.058. As the charge delocalization in 11-Zn is mostly
confined to the porphyrin−NMI core consisting of 84 non-H
atoms (excluding Zn), the charging capacity is ca. 0.095
electron per atom at the octaanion level. In comparison,
electron-deficient poly(quinoxaline) films could be charged
electrochemically to ca. 0.25 e/subunit (0.025 electron per
atom).91 Overall, the porphyrin−NMI combination present in
11-Zn emerges as an efficient means of storing multiple
negative charges in a relatively small π-conjugated manifold.
Experimental procedures and analytical data for all new
compounds. Additional NMR and mass spectra,
photoluminescence and electrochemistry data. X-ray data for
2, 5, 11-H2, and 11-Zn (CIF). Computational data tables, figures,
and Cartesian coordinates (PDB).
AUTHOR INFORMATION
Corresponding Author
* marcin.stepien@chem.uni.wroc.pl
Notes
The authors declare no competing financial interests.
ACKNOWLEDGMENT
CONCLUSIONS
Financial support from the National Science Center of Poland
(grant 2014/13/B/ST5/04394) is gratefully acknowledged.
Quantum chemical calculations were performed in the
Centers for Networking and Supercomputing of Wrocław and
Poznań. We thank Prof. Hellma Wennemers (ETH Zürich)
and Dr. Wojciech Bury (Uniwersytet Wrocławski) for helpful
discussions, Dr. Elżbieta Gońka for assistance with NIR
spectroscopy, and Dr. Miłosz Siczek for a powder diffraction
analysis. We thank reviewers for helpful comments.
The present work demonstrates
a
monomer-based
approach to bandgap engineering, with potentially wide-
ranging applications in oligopyrrole chemistry. In particular,
we have shown the first example of a synthetically useful
library of tunable pyrrole monomers, and the effective
transferability of bandgap changes to oligopyrrole derivatives.
In our donor–acceptor design, the five-membered ring at the
junction between the pyrrole donor and the naphthalene
acceptor ensures efficient π-conjugation, and has a potential
for creating soft (easily tunable) chromophores,68 as well as
organic materials with a small reorganization energy.92 The
modular character of our approach offers the advantage of
rapid elaboration of complex structures and the possibility of
juxtaposing different D–A units as an additional means of
bandgap control. Some of the acceptor groups introduced on
the D–A monomers, notably the imide group, can be easily
functionalized and also act as H-bonded elements66,67,93–96
stabilizing supramolecular assemblies. The electron-deficient
monopyrroles presented herein can further be viewed as
unprecedented “umpolung” analogues of TTF-pyrrole,97 with
reversed dipole orientations and comparable synthetic
utility.98–100
REFERENCES
(1)
Narita, A.; Wang, X.-Y.; Feng, X.; Müllen, K. Chem. Soc. Rev.
2015, 44, 6616–6643.
(2)
Stępień, M.; Gońka, E.; Żyła, M.; Sprutta, N. Chem. Rev.
2016, DOI 10.1021/acs.chemrev.6b00076.
(3)
Li, C.; Liu, M.; Pschirer, N. G.; Baumgarten, M.; Müllen, K.
Chem. Rev. 2010, 110, 6817–6855.
(4)
(5)
Müllen, K. ACS Nano 2014, 8, 6531–6541.
Zhu, X.; Tsuji, H.; López Navarrete, J. T.; Casado, J.;
Nakamura, E. J. Am. Chem. Soc. 2012, 134, 19254–19259.
(6) Morales-Vidal, M.; Boj, P. G.; Villalvilla, J. M.; Quintana, J.
A.; Yan, Q.; Lin, N.-T.; Zhu, X.; Ruangsupapichat, N.; Casado, J.; Tsuji,
H.; Nakamura, E.; Díaz-García, M. A. Nat. Commun. 2015, 6, 8458.
(7)
Li, Y.; Gao, J.; Di Motta, S.; Negri, F.; Wang, Z. J. Am. Chem.
The multi-charging capability shown here for the NMI- and
NDA-bearing porphyrins is a rare phenomenon in non-
fullerene aromatics, with few systems capable of four or more
reductions.101–104 11-Zn is apparently the first non-oligomeric π-
conjugated system for which a sequence of eight reversible
reductions is reported. Further optimization of such electron-
deficient porphyrins, which can be achieved by metal choice,
peripheral substitution, geometry changes etc., may lead to
even higher charge-per-atom densities at easily accessible
potentials, making such materials of interest in charge storage
applications. Simultaneously, the favorably positioned LUMO
level makes these new systems of potential interest as acceptor
Soc. 2010, 132, 4208–4213.
(8)
Yuan, Z.; Lee, S.-L.; Chen, L.; Li, C.; Mali, K. S.; De Feyter,
S.; Müllen, K. Chem. – Eur. J. 2013, 19, 11842–11846.
(9)
Zeng, Z.; Lee, S.; Zafra, J. L.; Ishida, M.; Zhu, X.; Sun, Z.; Ni,
Y.; Webster, R. D.; Li, R.-W.; López Navarrete, J. T.; Chi, C.; Ding, J.;
Casado, J.; Kim, D.; Wu, J. Angew. Chem. Int. Ed. 2013, 52, 8561–8565.
(10)
(11)
(12)
Tsuda, A.; Osuka, A. Science 2001, 293, 79–82.
Tanaka, T.; Osuka, A. Chem. Soc. Rev. 2015, 44, 943–969.
Yoshii, R.; Yamane, H.; Tanaka, K.; Chujo, Y.
Macromolecules 2014, 47, 3755–3760.
(13)
Shin, J.-Y.; Furuta, H.; Yoza, K.; Igarashi, S.; Osuka, A. J. Am.
Chem. Soc. 2001, 123, 7190–7191.
8
ACS Paragon Plus Environment

Page 9 of 11
Journal of the American Chemical Society
(14)
K. M.; Sessler, J. L. J. Am. Chem. Soc. 2003, 125, 6872–6873.
(15) Stępień, M.; Sprutta, N.; Latos-Grażyński, L. Angew. Chem.
Int. Ed. 2011, 50, 4288–4340.
Köhler, T.; Seidel, D.; Lynch, V.; Arp, F. O.; Ou, Z.; Kadish,
(50) Lash, T. D.; Chandrasekar, P. J. Am. Chem. Soc. 1996, 118,
8767–8768.
1
2
3
4
(51)
Ono, N.; Hironaga, H.; Ono, K.; Kaneko, S.; Murashima, T.;
Ueda, T.; Tsukamura, C.; Ogawa, T. J. Chem. Soc. [Perkin 1] 1996, No.
5, 417–423.
(16)
Hagberg, D. P.; Marinado, T.; Karlsson, K. M.; Nonomura,
K.; Qin, P.; Boschloo, G.; Brinck, T.; Hagfeldt, A.; Sun, L. J. Org. Chem.
2007, 72, 9550–9556.
(52)
(53)
Spence, J. D.; Lash, T. D. J. Org. Chem. 2000, 65, 1530–1539.
Ono, N.; Yamamoto, T.; Shimada, N.; Kuroki, K.; Wada, M.;
5
(17)
(18)
Kivala, M.; Diederich, F. Acc. Chem. Res. 2009, 42, 235–248.
Li, C.; Schöneboom, J.; Liu, Z.; Pschirer, N. G.; Erk, P.;
Utsunomiya, R.; Yano, T.; Uno, H.; Murashima, T. Heterocycles 2003,
61, 433–447.
(54) Okujima, T.; Ando, C.; Mack, J.; Mori, S.; Hisaki, I.; Nakae,
T.; Yamada, H.; Ohara, K.; Kobayashi, N.; Uno, H. Chem. – Eur. J. 2013,
19, 13970–13978.
6
7
8
9
Herrmann, A.; Müllen, K. Chem. – Eur. J. 2009, 15, 878–884.
(19) Achelle, S.; Barsella, A.; Baudequin, C.; Caro, B.; Robin-le
Guen, F. J. Org. Chem. 2012, 77, 4087–4096.
(20) Zöphel, L.; Enkelmann, V.; Müllen, K. Org. Lett. 2013, 15,
804–807.
(21)
S.; Jenekhe, S. A. Angew. Chem. Int. Ed. 2013, 52, 5513–5517.
(22) van Mullekom, H. A. M.; Vekemans, J. A. J. M.; Havinga, E.
E.; Meijer, E. W. Mater. Sci. Eng. R Rep. 2001, 32, 1–40.
(23) Beaujuge, P. M.; Amb, C. M.; Reynolds, J. R. Acc. Chem. Res.
2010, 43, 1396–1407.
(24) Zhang, Z.-G.; Wang, J. J. Mater. Chem. 2012, 22, 4178–4187.
(25)
2013, 135, 14920–14923.
(26) Chen, L.; Li, C.; Müllen, K. J. Mater. Chem. C 2014, 2, 1938–
1956.
(27)
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(55)
Ono, N.; Tsukamura, C.; Nomura, Y.; Hironaga, H.;
Murashima, T.; Ogawa, T. Adv. Mater. 1997, 9, 149–153.
(56) Johnstone, K. D.; Pearce, W. A.; Pyke, S. M. J. Porphyr.
Phthalocyanines 2002, 6, 661–672.
Li, H.; Kim, F. S.; Ren, G.; Hollenbeck, E. C.; Subramaniyan,
(57)
Zhou, Y.; Xiao, Y.; Chi, S.; Qian, X. Org. Lett. 2008, 10, 633–
636.
(58) Singha, S.; Kim, D.; Roy, B.; Sambasivan, S.; Moon, H.; Rao,
A. S.; Kim, J. Y.; Joo, T.; Park, J. W.; Rhee, Y. M.; Wang, T.; Kim, K. H.;
Shin, Y. H.; Jung, J.; Ahn, K. H. Chem. Sci. 2015, 6, 4335–4342.
(59) Newberry, R. W.; VanVeller, B.; Guzei, I. A.; Raines, R. T. J.
Am. Chem. Soc. 2013, 135, 7843–7846.
Li, H.; Kim, F. S.; Ren, G.; Jenekhe, S. A. J. Am. Chem. Soc.
(60) Wilhelm, P.; Lewandowski, B.; Trapp, N.; Wennemers, H. J.
Am. Chem. Soc. 2014, 136, 15829–15832.
Jiang, W.; Li, Y.; Wang, Z. Acc. Chem. Res. 2014, 47, 3135–
(61)
Miao, Q.; Lefenfeld, M.; Nguyen, T.-Q.; Siegrist, T.; Kloc, C.;
3147.
Nuckolls, C. Adv. Mater. 2005, 17, 407–412.
(62) Huang, L.; Stolte, M.; Bürckstümmer, H.; Würthner, F. Adv.
Mater. 2012, 24, 5750–5754.
(28) Würthner, F.; Saha-Möller, C. R.; Fimmel, B.; Ogi, S.;
Leowanawat, P.; Schmidt, D. Chem. Rev. 2015, 116, 962–1052.
(29) Suraru, S.-L.; Würthner, F. Angew. Chem. Int. Ed. 2014, 53,
7428–7448.
(30) Jänsch, D.; Li, C.; Chen, L.; Wagner, M.; Müllen, K. Angew.
Chem. Int. Ed. 2015, 54, 2285–2289.
(63) Arjona-Esteban, A.; Krumrain, J.; Liess, A.; Stolte, M.;
Huang, L.; Schmidt, D.; Stepanenko, V.; Gsänger, M.; Hertel, D.;
Meerholz, K.; Würthner, F. J. Am. Chem. Soc. 2015, 137, 13524–13534.
(64) Dou, J.-H.; Zheng, Y.-Q.; Yao, Z.-F.; Yu, Z.-A.; Lei, T.; Shen,
X.; Luo, X.-Y.; Sun, J.; Zhang, S.-D.; Ding, Y.-F.; Han, G.; Yi, Y.; Wang,
J.-Y.; Pei, J. J. Am. Chem. Soc. 2015, 137, 15947–15956.
(65) Dong, H.; Fu, X.; Liu, J.; Wang, Z.; Hu, W. Adv. Mater. 2013,
25, 6158–6183.
(66) Black, H. T.; Perepichka, D. F. Angew. Chem. Int. Ed. 2014,
53, 2138–2142.
(67) Black, H. T.; Lin, H.; Bélanger-Gariépy, F.; Perepichka, D. F.
Faraday Discuss. 2014, 174, 297–312.
(68) Mack, J.; Asano, Y.; Kobayashi, N.; Stillman, M. J. J. Am.
Chem. Soc. 2005, 127, 17697–17711.
(31)
Suraru, S.-L.; Zschieschang, U.; Klauk, H.; Würthner, F.
Chem. Commun. 2011, 47, 11504–11506.
(32)
T. Chem. – Eur. J. 2002, 8, 4742–4750.
(33)
71, 8098–8105.
(34)
Li, W.; Lin, Y.-Y.; Dodabalapur, A. Nature 2000, 404, 478–481.
(35)
M.; Strutt, N. L.; Cheng, C.; Carmieli, R.; Wasielewski, M. R.; Stoddart,
J. F. Angew. Chem. Int. Ed. 2013, 52, 13100–13104.
(36) Loudet, A.; Burgess, K. Chem. Rev. 2007, 107, 4891–4932.
Würthner, F.; Ahmed, S.; Thalacker, C.; Debaerdemaeker,
Thalacker, C.; Röger, C.; Würthner, F. J. Org. Chem. 2006,
Katz, H. E.; Lovinger, A. J.; Johnson, J.; Kloc, C.; Siegrist, T.;
Schneebeli, S. T.; Frasconi, M.; Liu, Z.; Wu, Y.; Gardner, D.
(69) Lindsey, J. S. Acc. Chem. Res. 2010, 43, 300–311.
(70) Myśliwiec, D.; Donnio, B.; Chmielewski, P. J.; Heinrich, B.;
Stępień, M. J. Am. Chem. Soc. 2012, 134, 4822–4833.
(37)
(38)
Wood, T. E.; Thompson, A. Chem. Rev. 2007, 107, 1831–1861.
Sessler, J. L.; Aguilar, A.; Sanchez-Garcia, D.; Seidel, D.;
(71)
Long, T. M.; Swager, T. M. Adv. Mater. 2001, 13, 601–604.
Köhler, T.; Arp, F.; Lynch, V. M. Org. Lett. 2005, 7, 1887–1890.
(39) Gońka, E.; Myśliwiec, D.; Lis, T.; Chmielewski, P. J.; Stępień,
M. J. Org. Chem. 2013, 78, 1260–1265.
(40) Kadish, K. M.; Smith, K. M.; Guilard, R. Handbook of
Porphyrin Science; World Scientific Publishing: Singapore; Vol. 1–35.
(72)
Tsui, N. T.; Paraskos, A. J.; Torun, L.; Swager, T. M.; Thomas,
E. L. Macromolecules 2006, 39, 3350–3358.
(73) Barbour, L. J. Chem. Commun. 2006, No. 11, 1163.
(74) Turner, M. J.; McKinnon, J. J.; Jayatilaka, D.; Spackman, M.
A. CrystEngComm 2011, 13, 1804–1813.
(41)
Takase, M.; Enkelmann, V.; Sebastiani, D.; Baumgarten, M.;
(75)
McKeown, N. B.; Makhseed, S.; Msayib, K. J.; Ooi, L.-L.;
Müllen, K. Angew. Chem. Int. Ed. 2007, 46, 5524–5527.
(42) Takase, M.; Narita, T.; Fujita, W.; Asano, M. S.; Nishinaga,
T.; Benten, H.; Yoza, K.; Müllen, K. J. Am. Chem. Soc. 2013, 135, 8031–
8040.
Helliwell, M.; Warren, J. E. Angew. Chem. Int. Ed. 2005, 44, 7546–7549.
(76) Mastalerz, M.; Oppel, I. M. Angew. Chem. Int. Ed. 2012, 51,
5252–5255.
(77)
Chen, T.-H.; Popov, I.; Kaveevivitchai, W.; Chuang, Y.-C.;
(43)
Gońka, E.; Chmielewski, P. J.; Lis, T.; Stępień, M. J. Am.
Chen, Y.-S.; Daugulis, O.; Jacobson, A. J.; Miljanić, O. Š. Nat. Commun.
2014, 5, 5131.
(78) Slater, A. G.; Cooper, A. I. Science 2015, 348, aaa8075.
(79) Kumar, P. P.; Maiya, B. G. New J. Chem. 2003, 27, 619–625.
(80) Cosmo, R.; Kautz, C.; Meerholz, K.; Heinze, J.; Müllen, K.
Angew. Chem. Int. Ed. Engl. 1989, 28, 604–607.
Chem. Soc. 2014, 136, 16399–16410.
(44) Żyła, M.; Gońka, E.; Chmielewski, P. J.; Cybińska, J.; Stępień,
M. Chem. Sci. 2016, 7, 286–294.
(45) Heinze, J.; Frontana-Uribe, B. A.; Ludwigs, S. Chem. Rev.
2010, 110, 4724–4771.
(46) Jiao, C.; Huang, K.-W.; Chi, C.; Wu, J. J. Org. Chem. 2011, 76,
(81)
Connelly, N. G.; Geiger, W. E. Chem. Rev. 1996, 96, 877–910.
661–664.
(82) Reed, C. A. In Electrochemical and Spectrochemical Studies
of Biological Redox Components; Advances in Chemistry; American
Chemical Society: Washington, D.C., 1982; Vol. 201, pp 333–356.
(47) Jiao, C.; Zu, N.; Huang, K.-W.; Wang, P.; Wu, J. Org. Lett.
2011, 13, 3652–3655.
(48) Jiao, C.; Huang, K.-W.; Wu, J. Org. Lett. 2011, 13, 632–635.
(49) Chandrasekar, P.; Lash, T. D. Tetrahedron Lett. 1996, 37,
4873–4876.
(83)
Müllen, K. Chem. Rev. 1984, 84, 603–646.
(84) Minsky, A.; Meyer, A. Y.; Rabinovitz, M. J. Am. Chem. Soc.
1982, 104, 2475–2482.
9
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 10 of 11
(85) Becker, B. C.; Huber, W.; Müllen, K. J. Am. Chem. Soc. 1980,
102, 7803–7805.
(96) McMorran, D. A.; McAdam, C. J.; Salm, H. van der; Gordon,
K. C. Dalton Trans. 2013, 42, 2948–2962.
1
2
3
4
5
6
7
8
(86) Müllen, K.; Huber, W.; Meul, T.; Nakagawa, M.; Iyoda, M. J.
Am. Chem. Soc. 1982, 104, 5403–5411.
(87) Ayalon, A.; Rabinovitz, M.; Cheng, P.-C.; Scott, L. T. Angew.
Chem. Int. Ed. Engl. 1992, 31, 1636–1637.
(88) Baumgarten, M.; Gherghel, L.; Wagner, M.; Weitz, A.;
Rabinovitz, M.; Cheng, P.-C.; Scott, L. T. J. Am. Chem. Soc. 1995, 117,
6254–6257.
(89) Zabula, A. V.; Filatov, A. S.; Spisak, S. N.; Rogachev, A. Y.;
Petrukhina, M. A. Science 2011, 333, 1008–1011.
(90) Zhen, Y.; Wang, C.; Wang, Z. Chem. Commun. 2010, 46,
1926–1928.
(97) Jeppesen, J. O.; Takimiya, K.; Jensen, F.; Becher, J. Org. Lett.
1999, 1, 1291–1294.
(98) Becher, J.; Brimert, T.; Jeppesen, J. O.; Pedersen, J. Z.;
Zubarev, R.; Bjørnholm, T.; Reitzel, N.; Jensen, T. R.; Kjaer, K.;
Levillain, E. Angew. Chem. Int. Ed. 2001, 40, 2497–2500.
(99) Nielsen, K. A.; Cho, W.-S.; Jeppesen, J. O.; Lynch, V. M.;
Becher, J.; Sessler, J. L. J. Am. Chem. Soc. 2004, 126, 16296–16297.
(100) Takase, M.; Yoshida, N.; Nishinaga, T.; Iyoda, M. Org. Lett.
2011, 13, 3896–3899.
9
(101) Naoda, K.; Mori, H.; Aratani, N.; Lee, B. S.; Kim, D.; Osuka,
A. Angew. Chem. Int. Ed. 2012, 51, 9856–9859.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(91)
Yamamoto, T.; Sugiyama, K.; Kushida, T.; Inoue, T.;
(102) Chou, C.-M.; Saito, S.; Yamaguchi, S. Org. Lett. 2014, 16,
2868–2871.
(103) Mori, H.; Tanaka, T.; Lee, S.; Lim, J. M.; Kim, D.; Osuka, A.
J. Am. Chem. Soc. 2015, 137, 2097–2106.
(104) Zhang, G.; Lami, V.; Rominger, F.; Vaynzof, Y.; Mastalerz,
M. Angew. Chem. Int. Ed. 2016, 55, 3977–3981.
Kanbara, T. J. Am. Chem. Soc. 1996, 118, 3930–3937.
(92) Chen, W.-C.; Chao, I. J. Phys. Chem. C 2014, 118, 20176–
20183.
(93) Houlton, A.; Michael, D.; Mingos, P.; Williams, D. J. Transit.
Met. Chem. 1994, 19, 653–656.
(94) Bishop, M. M.; Lindoy, L. F.; Turner, P. Supramol. Chem.
2002, 14, 179–188.
(95) Bishop, M. M.; Coles, S. J.; Lindoy, L. F.; Parkin, A.
Inorganica Chim. Acta 2006, 359, 3565–3580.
(105) Anthony, J. E. Chem. Mater. 2011, 23, 583–590.
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