Bis(aminoaryl) Carbon-Bridged Oligo(phenylenevinylene)s Expand the Limits of Electronic Couplings

Article abstract of DOI:10.1002/anie.201610921

Carbon-bridged bis(aminoaryl) oligo(para-phenylenevinylene)s have been prepared and their optical, electrochemical, and structural properties analyzed. Their radical cations are class III and class II mixed-valence systems, depending on the molecular size

Full text of DOI:10.1002/anie.201610921

Angewandte
Communications
Chemie
International Edition: DOI: 10.1002/anie.201610921
German Edition: DOI: 10.1002/ange.201610921
Charge Transfer
Bis(Aminoaryl) Carbon-Bridged Oligo(phenylenevinylene)s Expand
the Limits of Electronic Couplings
Paula Mayorga Burrezo, Nai-Ti Lin, Koji Nakabayashi, Shin-ichi Ohkoshi, Eva M. Calzado,
Pedro G. Boj, Marꢀa A. Dꢀaz Garcꢀa, Carlos Franco, Concepciꢁ Rovira, Jaume Veciana,
Michael Moos, Christoph Lambert, Juan T. Lꢂpez Navarrete, Hayato Tsuji,* Eiichi Nakamura,*
and Juan Casado*
Abstract: Carbon-bridged bis(aminoaryl) oligo(para-phenyl-
enevinylene)s have been prepared and their optical, electro-
chemical, and structural properties analyzed. Their radical
cations are class III and class II mixed-valence systems,
depending on the molecular size, and they show electronic
couplings which are among the largest for the self-exchange
reaction of purely organic molecules. In their dication states,
the antiferromagnetic coupling is progressively tuned with size
from quinoidal closed-shell to open-shell biradicals. The data
prove that the electronic coupling in the radical cations and the
singlet–triplet gap in the dications show similar small attenu-
ation factors, thus allowing charge/spin transfer over rather
large distances.
providing carbon-bridged oligo(para-phenylenevinylene)s
(COPVs; Scheme 1).
[
2–8]
COPVs have the vinylenes embedded within bicyclo-
[3.3.0]octene moieties and strain the double-bond, thus
pushing the ground electronic state towards a much more
[
3,6]
electro-optically active p-conjugated C=C/CꢀC backbone.
This structural motif contributes to improved molecular
properties, such as low oxidation potentials and high fluores-
cence quantum yield (F ꢁ 1), as well as outstanding chemical
f
stability owing to blocking the vinylene isomerization and
steric protection by the carbon-bridge substituents. These
features enabled us to demonstrate their utilities in applica-
[
5]
[7]
tions in photovoltaics, and more recently in organic lasers.
Significantly COPVs have been reported to display very large
photoinduced electron-transfer rates for excited state charge
separation and recombination in a donor-COPV(bridge)-
acceptor configuration (Zn-COPVn-C60 in Scheme 1), and is
O
ligo(phenylenevinylene) (OPVs) compounds are stellar
[1]
molecules in organic electronics. Recently their fused and
planar derivatives have been prepared by inserting carbon
bridges between the phenylene and vinylene units, thus
[*] Dr. P. M. Burrezo, Prof. J. T. Lꢀpez Navarrete, Prof. J. Casado
Department of Physical Chemistry, University of Mꢁlaga
29071 Mꢁlaga (Spain)
E-mail: casado@uma.es
Dr. N.-T. Lin, Dr. K. Nakabayashi, Prof. S.-i. Ohkoshi, Dr. H. Tsuji,
Prof. E. Nakamura
Department of Chemistry, School of Science, The University of Tokyo
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
E-mail: tsujiha@kanagawa-u.ac.jp
nakamura@chem.s.u-tokyo.ac.jp
Dr. E. M. Calzado, Dr. P. G. Boj, Prof. M. A. Dꢂaz Garcꢂa
Dpto. Fꢂsica, Ingenierꢂa de Sistemas y Teorꢂa de la SeÇal
Dpto. ꢃptica and Dpto de Fꢂsica Aplicada and Instituto Universitario
de Materiales de Alicante, Universidad de Alicante
Alicante 03080 (Spain)
C. Franco, Prof. C. Rovira, Prof. J. Veciana
Department of Molecular Nanoscience and Organic Materials
Institut de Ciꢄncia de Materials de Barcelona (ICMAB-CSIC) and
Networking Research Center on Bioengineering, Biomaterials and
Nanomedicine (CIBER-BBN)
Campus de la UAB, Bellaterra 08193 (Spain)
M. Moos, Prof. C. Lambert
Institut fꢅr Organische Chemie, Universitꢆt Wꢅrzburg
Am Hubland, 97074 Wꢅrzburg (Germany)
Dr. H. Tsuji
Present address: Department of Chemistry, Faculty of Science,
Kanagawa University, Kanagawa 259-1293 (Japan)
Supporting information for this article can be found under:
http://dx.doi.org/10.1002/anie.201610921.
Scheme 1. Most significant COPV derivatives studied. Ar=4-octyl-
phenyl, and R=CH , Ph, or Ar (p-octylphenyl); (see Scheme S1).
3
Angew. Chem. Int. Ed. 2017, 56, 1 – 6
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
These are not the final page numbers!

Angewandte
Communications
Chemie
ascribed to efficient electronic tunneling and electron-vibra-
Scheme 2 summarizes the synthesis of the DA(COPVn)
units, which were obtained in good to moderate yields (62–
88%) using a palladium-catalyzed amination reaction from
the corresponding dibromides. Their chemical characteriza-
tion (Schemes S2 and S3 and Figures S2–S16), and their
electrochemical (Figures S17–S20 and Table S1), spectroelec-
trochemical (Figures S21–S24) and optical properties
(Scheme S4, Figures S25–S29) are provided.
Absorption and photoluminescence (PL) spectra of DA-
(COPVn) in Figure 1a are considerably red-shifted compared
to the open unbridged DA(OPVn). Furthermore, DA-
(COPV2) discloses amplification of spontaneous emission
[8]
tion coupling enabled by the COPV bridge. This study,
however, has raised new questions: Does donor–acceptor
charge-transfer take place in the ground electronic state of
COPVs [i.e., mixed-valence (MV) behavior] as efficiently as
in the photoinduced excited electronic state? How does this
performance compare to other known mixed-valence sys-
tems? How significant is their size-dependent transport
behavior? These questions motivated us to design new
donor-bridge-donor MV molecules using COPV cores as
bridges.
[
9–11]
MV systems
offer a unique context for the study of
intramolecular charge transfer (charge delocalization) within
molecules. The MV property arises after a one-electron
oxidation of donor-p(bridge)-donor molecules, where a com-
petition for the positive charge occurs between the donors
[
12]
through the p-conjugated bridge. Robin and Day divided
MV species into two main groups: 1) class III, with full charge
delocalization between the donors through the bridge, and
2
) class II, where the charge resides on one of the donors and
[13]
the bridge stops delocalization. In the Marcus–Hush theory,
there are two main parameters that control class II/III effects:
) the electronic coupling (V ) between the two donor
1
1
2
groups, and 2) the reorganization energy (lreorg). Both are
strongly dependent on the nature of the bridge: class III MV
species obey 2V > l , and conversely, 2V < l applies
reorg
1
2
reorg
12
for class II. In particular, designing compounds with 2V ꢁ
1
2
l
reorg
is challenging given their borderline character. Conse-
quently, p-conjugation, conformation, and length (donor
separation) of the bridge should be carefully chosen to
control the class III/II character. Intimately related to the MV
behavior of the monovalent cations is the shape of the
divalent dications, either bipolarons (associated with class III)
Figure 1. a) Absorption, PL, and ASE (shaded band) spectra of DA-
(COPV2) in polystyrene. b) Electrochemically obtained UV/Vis-NIR
absorption spectra of the radical cations (RC) and dications (DC,
shaded bands) of DA(COPV1), DA(COPV2), DA(COPV3), and DA-
(COPV4)as shown in order from the bottom to the top. c) Oxidation
UV/Vis-NIR spectroelectrochemistry of DA(COPV3) in CH Cl /0.1m
[14]
or polaron pairs (associated with class II).
2
2
Here we focus on the size-dependent behavior of the
COPVn bridges having a different number of repeating units
terminated with bis(arylamino) groups [DA(COPVn);
Scheme 2 and see Figure S1 in the Supporting Information].
nBu NPF at 228C (neutral: black, radical cation: red, dication: blue,
4
6
radical trication: green, and tetracation: purple). d) Electrochemically
obtained EPR spectra of the radical cations of DA(COPV1) (bottom)
and of DA(COPV4) (top).
(ASE) at a much longer wavelength (lASE = 534 nm) than
COPV2 (lASE = 463 nm), and is relevant for fine tuning the
[
15]
spectrum of ASE emission.
COPV3,
Regarding unsubstituted
[3]
the number of oxidations in DA(COPV3)
increases and the first two anodic processes appear at lower
and differentiated potentials, however in DA(COPV4), they
almost collapse into one two-electron process. DA(COPV3)
and DA(COPV4) display reversible electrochemical forma-
tion of up to a tetracation and pentacation, respectively.
Figure 1c shows the UV/Vis-NIR spectroelectrochemical
characterization of DA(COPV3) and the identifying spectra
of the four consecutive oxidation states: radical cation,
dication, radical trication, and tetracation.
Scheme 2. Synthesis of DA(COPVn). dba=dibenzylideneacetone.
By oxidation, the charge-transfer process or MV behavior in
the ground electronic state was activated. Thus, radical
+
2+
cations [DA(COPVn)C ] and dications [DA(COPVn) ] of
variable lengths, from a monomer to a tetramer, have been
studied and the large electronic couplings in the MV cations
The UV/Vis-NIR absorption spectra of the pure radical
cations (RC) were extracted from the spectroelectrochemis-
try data in Figures 1b and Figures S21–S24. These spectra are
characterized by the presence of two main bands at 18000–
(
class III) and the large antiferromagnetic bonding in the
dications (closed-shell quinoidals) have been correlated.
However, when V12 attenuates with length, the cation of
DA(COPV4) become class II and its dication an open-shell
singlet diradical.
ꢀ
1
ꢀ1
15000 cm and at 7500–5000 cm (HOMO!SOMO tran-
sition as supported by DFT computations; Table 1), which
2
www.angewandte.org
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2017, 56, 1 – 6
These are not the final page numbers!

Angewandte
Communications
Chemie
ꢀ
1
Table 1: Spectroscopic data of the lowest-energy band of the MV radical cations,
together with inter-charge distance and electronic couplings. (See Figures S30–S38
and Tables S3–S9.)
a similar N-N distance (V = 2400 cm , R
=
N-N
1
2
[
19]
1
2.5 ꢀ). The latter has almost the same coupling
as DA(COPV2)C (V = 2410 cm , R = 17.6 ꢀ),
but at a much shorter N-N distance. Likewise, for
+
ꢀ1
1
2
N-N
+
DA(COPVn)C
ꢀv
cm
emax
[m cm
mab Dm
RN-N
[ꢇ]
V12
[cm
DE
[eV]
DE
[cm
max
1 [f]
ab
[a]
ST
ꢀ1 [e]
ꢀ
ꢀ1
ꢀ1
[b]
[a]
ꢀ1
+
ꢀ1
[
]
]
[D] [D]
]
]
DA(COPV4)C
the coupling (V = 1450 cm ,
12
[
c]
RN-N = 29.8 ꢀ) is slightly larger at more than twice
the N-N distance than that of a bis(triarylamine)
with a diethynylbenzene bridging the two triaryl-
n=1
n=2
n=3
n=4
7190
4820
4330
5010
41200
69300
80500
68600
13.0 0.2 11.54 3600 0.671
618
[
c]
16.8 0.9 17.59 2410 0.591
482
356
244
[
c]
18.9 0.4 23.67 2170 0.464
[
d]
13.3 37.4 29.76 1450 0.269
ꢀ1
[20]
amines (V = 1000 cm , R = 12.5 ꢀ).
Open
1
2
N-N
[
[
a] From DFTcalculations. [b]ꢂ10%. [c] Using Equation (1). [d] Using Equation (2).
e] DE =E for DA(COPVn) . [f]ꢂ5%.
ꢀE
unbridged MV radical cation homologues, DA-
(OPV3) and DA(OPV4), do not even show an IV-
2+
ST
Triplet
Singlet
[
21]
CT band (vanishing coupling). The attenuation
+
factor, b, in Figure 2 for DA(COPVn)C gives
ꢀ
1
progressively red-shift with the chain length (except in the
a value of 0.092 ꢀ , thus characterizing the superexchange
behavior for charge self-exchange in their ground electronic
state. For the (donor)-COPVn-(acceptor) Zn-COPVn-C
+
+
case of DA(COPV3)C !DA(COPV4)C ). In general, in
class II MV species, the lowest energy band describes an
intervalence charge transfer (IV-CT) with a well-defined
symmetric Gaussian shape. Conversely, for class III, this
band no longer has IV-CT character and its shape is
asymmetric and narrow, and are clearly the cases for n = 1–
6
ꢀ
0
1
compounds with n = 1–4 (Scheme 1), a small b = 0.056 ꢀ
[
16]
ꢀ1
for excited state charge separation (CS) and b = 0.078 ꢀ for
[
8]
charge recombination (CR) are reported.
3
. For these class III MV compounds, V12 is given by
+
Equation (1) in Table 1. For DA(COPVn)C n = 1–3, DFT
ꢀ
v
max
2
V
12
¼
ð1Þ
computations indicate a vanishing dipole-moment change
between ground and excited electronic states, Dm , and is
ab
typical for delocalized class III radical cations. For DA-
+
(
COPV4)C , the lowest-energy absorption band is more
Figure 2. Left: representation of absorption energies for the absorp-
tions of the neutral (N blue circles), radical cations (RC1 and
RC2 squares), and dications (DC1 and DC2 red circles) versus 1/n; see
labels in Figure 1. Right: ln(V ) and ln(DE ) versus inter-donor
symmetric and DFT gives a dipole moment difference of
7 D (see Table S9), thus revealing localized class II behavior.
In this case, the electronic coupling can be calculated using
3
1
2
ST
[
17]
the Mulliken–Hush theory [Eq. (2)] where the transition
distance (RN-N, Table 1) according to the formula: ln(f)=ln(f
0
)ꢀb/2(RN-
N) RN-N where f=V12 or f=DEST and b is the attenuation factor.
qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
m ~v
DEST =ETtripletꢀESinglet at the (U)B3LYP/6-31G** level.
ab max
2
2
ab
V
12
¼
with Dm12
¼
Dm þ 4m
ð2Þ
ab
Dm12
These radical cations have also been studied by EPR
moment (evaluated by integration of the lowest energy
(
Figure 1d; see Figures S39–S41). The EPR spectrum of
absorption band; see the Supporting Information), m , is
ab
+
DA(COPV1)C shows a five-line spectrum which results from
the coupling of the odd electron with the two terminal
nitrogen nuclei in either a delocalized class III or a fast-
exchange regime typical of class II species with a large
V12 value. For the longer cations, the same is observed in their
the projection of the adiabatic transition dipole moment of
the IV-CT band onto the diabatic dipole moment difference,
Dm , of formally fully localized (noninteracting) diabatic
ab
[
18]
states.
dipole moment difference (see the Supporting Information).
For Dmab we used the DFT computed adiabatic
+
ꢀ
1
+
EPR spectra, thus indicating that even for the DA(COPV4)C
class II mixed-valence species, the V12 coupling is
In this way we evaluated V = 1450 cm for DA(COPV4)C ,
1
2
which is still quite sizable given the length (RN-N = 30 ꢀ) of
large enough to feature the molecules in the fast-exchange
the compound.
+
+
regime of the EPR technique. For DA(COPV4)C , an
In addition, for DA(COPV4)C the resonance stabilization
energy [Eq. (3)] gives DG = ꢀ844 cm (ꢀ105 mV) com-
ꢀ1
approximate energy barrier for charge transfer of
r
2
12
ꢀ1
*
DG ¼ l=4 ꢀ V þ V =l = 210 cm is deduced and in line
1
2
2
with a fast charge transference.
2V12
ð3Þ
DG ¼ ꢀ
r
The UV/Vis-NIR electronic absorption spectra of the
l
2
+
DA(COPVn) are in Figure 1b and are mainly characterized
by a strong absorption band resulting from the HOMO!
LUMO excitation which appears in the middle of the two
bands of the radical cation. Whereas the spectra of the cations
showed an anomalous blue-shift of the IV-CT band from
pared to the 0.065 V derived from a digital fit of the CV. The
V12 of the compounds studied here can be compared with
those having comparable N–N distances from the literature.
+
ꢀ1
For example, for DA(COPV1)C , the coupling V = 3600 cm
1
2
+
+
(RN-N = 11.5 ꢀ) is much larger than that of a bis(triarylamine),
DA(COPV3)C !DA(COPV4)C (e.g., transition from a delo-
which has a triple bond bridging the two triarylamines and
calized class III to localized class II), the absorption spectra of
Angew. Chem. Int. Ed. 2017, 56, 1 – 6
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3
These are not the final page numbers!

Angewandte
Communications
Chemie
+
2+
the dications also display a distinctive feature from the trimer
NIR spectra of DA(COPV4)C and DA(COPV4) resemble
each other. From the optical spectra, the energy difference
between the RC2 and DC/DC2 absorption bands in DA-
2
+
to the tetramer, hence, the spectrum of DA(COPV4) is
composed of a new additional high-energy band at about
ꢀ
1
[11]
+
2+
1
3300 cm , and it is formed by a pair of bands.
EPR
(COPVn)C /DA(COPVn) can be defined (DE in Table 1).
DE decreases with n, in parallel with the progressive
conversion of the closed-shell quinoidal dication into an
spectra of the four dications are silent, thus indicating singlet
ground electronic states.
2
+
[23]
Attempts to crystallize DA(COPV1) were unsuccessful.
Instead, molecule with methoxyphenyl groups
DA(COPV1-OCH )] replacing hexyloxyphenyls was pre-
open-shell biradical.
In addition, in the dications, the
a
energy difference between the singlet ground electronic
state (closed-shell or open-shell) and the low-energy-lying
triplet excited state (DEST in Table 1) have been calculated at
the DFT/(U)B3LYP/6-31G** level. DEST represents the
antiferromagnetic bonding interaction, and it is always
positive and decreases with chain-length, thus revealing
that: 1) the singlet character of the ground electronic state
in accordance with the silent EPR spectra, and 2) the
accentuation of the biradical character in DA(COPV3)
and DA(COPV4) because of the recovery of the aroma-
ticity in a larger number of benzenes, and is in agreement with
the findings in biradicals of unsubstituted COPV dications.
DEST is further adjusted to the logarithmic equation in
Figure 2 and an attenuation factor, b = 0.1 ꢀ , is obtained,
and it is similar to that of V , thus emphasizing the role of the
[
3
pared and yielded single crystals of the dication which were
suitable for X-ray analysis (Figure 3). The crystal packing
2
+
2
+
[6]
ꢀ1
1
2
p-bridge. Indeed, V12 and DEST both depend on the wave-
function overlaps in the bridge between the terminal parts, so
that they have a common origin and consequently similar
b value.
The comparison of the infrared and Raman spectra of
these redox species (see Figure 3; see Figure S43 and
Tables S9–S15) provides a unified structural vision. Vibra-
tional spectroscopy establishes that the IR and Raman
spectra display complementary features in molecules having
an inversion center for the point-group symmetry. In a strict
sense, these molecules do not have it because of the lateral
aryl chains. However, since the relevant features are due to
the p-core, this segment has a local inversion center making
the IR/Ra spectra complementary, as seen in the neutral
compounds in Figure 3. As in the neutrals, this criteria is also
[
25]
Figure 3. Top: X-ray structure of a model compound, DA(COPV1-
2
+
ꢀ
OCH3) , showing the disposition of the SbF6 anions and main CC
distances, together with comparison of the IR/Raman spectra in
dichloromethane solutions of neutral (N), radical cation (RC), and
dication (DC) of DA(COPV4). Bottom: canonical forms of radical
cations and dications [see the Supporting Information for a discussion
2
+
on DA(COPV1) ]. Lateral substitution is omitted for clarity.
2
+
fulfilled for the IR/Ra spectra of DA(COPV4) because of
the symmetric delocalization of the two charges in the p-core.
For the radical cation of DA(COPV4), the IR/Ra spectra
display the same strong bands either in IR and in Raman,
a non-complementary effect emerging from the rupture of
symmetry by localization of the positive charge in one part of
the molecule or class II localized MV species (see structures
ꢀ
shows a well-ordered distribution of the two SbF6 counter-
anions disposed with two fluorine atoms anchored in each
benzene along the main molecular plane with distances of
3
.1–3.4 ꢀ, typical for fluoride(anion)–p interactions. The
perfectly ordered anions indicates that the positive charge
2
+
on the DA(COPV1-OCH )
core is fully delocalized.
3
2
+
+
DA(COPV1-OCH3) has a reversed C=C/CꢀC path regard-
in Figure 3). Conversely, in DA(COPV1)C the IR/Ra com-
parison in Figure S43 follows the complementary effect for
ing its neutral state (the central vinylene bond changes by
1
.349!1.413 ꢀ on neutral!dication) and the terminal CꢀN
the three redox states, thus indicating the existence of a fully
delocalized positive charge in the p-path of DA(COPV1)C ,
+
bonds are strongly shortened (see Figure S42). This structure
[
22]
is in line with a quinoidal closed-shell dication
corroborated by its NMR active spectrum.
further
and is in agreement with a class III MV species and a full
2
+
closed quinoidal structure in DA(COPV1) . The Raman
spectra provide an additional piece of information regarding
2
+
The anomalous pair of bands for DA(COPV4) reveals
the rupture of the well-defined quinoidal structure in DA-
COPV1-3) , which becomes either an open-shell bis(radical
cation)s or polaron pair. The lowest-energy band of the
polaron pair dication can be attributed to a dipole-allowed
[
6,24]
the structures of the charged species.
From DA-
2
+
+
2+
(
(COPV1)C !DA(COPV1)
the main Raman band at
1600 cm [due to the n(C=C) modes of the benzenes]
[
22]
ꢀ1
ꢀ
1
varies as 1596!1592 cm , a frequency downshift resulting
[23]
excitation which takes place between the two polarons in
such a way that it coalesces in the limit of infinite separation
or zero orbital overlap (the polaron-pair is reduced to two
individual polarons). This behavior explains why the UV/Vis-
from the enlargement of the quinoidal structure. However, on
+
2+
DA(COPV4)C !DA(COPV4) , these bands upshift from
1587!1592 cm , thus revealing the transformation of the
dication towards a pseudoaromatic structure.
ꢀ
1
[6]
4
www.angewandte.org
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2017, 56, 1 – 6
These are not the final page numbers!

Angewandte
Communications
Chemie
In summary, a new series of carbon-bridged bis(ami-
noaryl) oligo(para-phenylenevinylene)s have been prepared.
As radical cations, they show the largest electronic couplings
among the mixed-valence oligo(phenylenevinylene) series
and in related purely organic systems of comparable p-
[3] X. Zhu, H. Tsuji, J. T. Lꢂpez Navarrete, J. Casado, E. Nakamura,
J. Am. Chem. Soc. 2012, 134, 19254 – 19259.
[
[
4] X. Zhu, H. Tsuji, K. Nakabayashi, S.-i. Ohkoshi, E. Nakamura, J.
Am. Chem. Soc. 2011, 133, 16342 – 16345.
5] X. Zhu, H. Tsuji, A. Yella, A. S. Chauvin, M. Grꢃtzel, E.
Nakamura, Chem. Commun. 2013, 49, 582 – 584; J. Sukegawa, H.
Tsuji, E. Nakamura, Chem. Lett. 2014, 43, 699 – 701; Q. Yan, Y.
Guo, A. Ichimura, H. Tsuji, E. Nakamura, J. Am. Chem. Soc.
2016, 138, 10897 – 10904.
[
14]
electron size. The planar, rigid, and strained COPV core
allows greater distances for the self-exchange electron-trans-
fer reaction. The short and medium dications exhibit a strong
antiferromagnetic coupling for all their electrons in the
ground electronic state, thus imposing a closed-shell quinoidal
[
6] P. Mayorga Burrezo, X. Zhu, S.-F. Zhu, Q. Yan, J. T. Lꢂpez Na-
varrete, H. Tsuji, E. Nakamura, J. Casado, J. Am. Chem. Soc.
2015, 137, 3834 – 3843.
2
+
structure. In the longest dication, DA(COPV4) , the anti-
ferromagnetic exchange is weakened and leads to the
development of a singlet open-shell biradicaloid ground
electronic state. In contrast, large V12 and DEST values dictate,
respectively, full delocalized class III MV radical cations and
full quinoidal dications, whereas their diminution transform
into localized class II MV cations and open-shell biradical
dications. Furthermore, the small attenuation factors permit
the expansion of the electronic stimuli to rather large spatial
limits. The discovery of molecular platforms, where charge
and spin transfer could cover increasingly greater distances, is
a key aspect in the field on single-molecular conductance and
also in the design of more efficient semiconductors in organic
electronics. For these fields, the COPV compounds are
promising new candidates.
[
7] M. Morales-Vidal, P. G. Boj, J. M. Villavilla, J. A. Quintana, Q.
Yan, N.-T. Lin, X. Zhu, N. Ruangsupapichat, J. Casado, H. Tsuji,
E. Nakamura, M. A. Dꢄaz Garcꢄa, Nat. Commun. 2015, 6, 8458.
[8] J. Sukegawa, C. Schubert, X. Zhu, H. Tsuji, D. M. Guldi, E.
Nakamura, Nat. Chem. 2014, 6, 899 – 905.
[
9] D. O. Cowan, C. LeVanda, J. Park, F. Kaufman, Acc. Chem. Res.
973, 6, 1 – 7.
1
[
[
10] J. Hankache, O. S. Wenger, Chem. Rev. 2011, 111, 5138 – 5178.
11] a) A. Heckmann, C. Lambert, Angew. Chem. Int. Ed. 2012, 51,
326 – 392; Angew. Chem. 2012, 124, 334 – 404; b) C. Lambert,
Triarylamine-Based Organic Mixed-Valence Compounds: The
Role of the Bridge in Organic Redox Systems (Ed.: T. Nishinaga),
Wiley, Hoboken, 2016, chap. 7, p. 244 – 268.
[
12] M. B. Robin, P. Day, Adv. Inorg. Chem. Radiochem. 1967, 10,
247.
[
[
13] R. A. Marcus, Annu. Rev. Phys. Chem. 1964, 15, 155 – 196.
14] S. Barlow, C. R. Risko, S. A. Odom, S. Zheng, V. Coropceanu, L.
Beverina, J.-L. Brꢅdas, S. R. Marder, J. Am. Chem. Soc. 2012,
1
34, 10146 – 10155.
[15] N. Tsutsumi, T. Kawahira, W. Sakai, Appl. Phys. Lett. 2003, 83,
533 – 2535.
Acknowledgments
2
[
16] S. Barlow, C. Risko, S. J. Chung, N. M. Tucker, V. Coropceanu,
We thank MINECO of the Spanish Government (CTQ2015-
S. C. Jones, Z. Levi, J. L. Brꢅdas, S. R. Marder, J. Am. Chem. Soc.
6
9391-P, CTQ2013-40480-R and MAT2015-66856-R) for their
2005, 127, 16900 – 16911.
support. We also thank the Research Central Services (SCAI)
of the University of Mꢁlaga. This work is partially supported
by Grant-in-Aid for Scientific Research (16H04106 to HTand
[
17] N. S. Hush, Coord. Chem. Rev. 1985, 64, 135 – 157.
[18] M. Renz, K. Theilacker, C. Lambert, M. Kaupp, J. Am. Chem.
Soc. 2009, 131, 16292 – 16302.
[
[
[
19] S. Amthor, C. Lambert, J. Phys. Chem. A 2006, 110, 1177 – 1189;
S. V. Lindeman, S. V. Rosokha, D. Sun, J. K. Kochi, J. Am. Chem.
Soc. 2002, 124, 843 – 855.
20] C. Lambert, G. Nçll, J. Am. Chem. Soc. 1999, 121, 8434 – 8442;
H.-J. Nie, C.-J. Yao, J.-Y. Shao, J. Yao, Y.-W. Zhong, Chem. Eur.
J. 2014, 20, 17454 – 17465.
21] S. Zheng, S. Barlow, C. Risko, T. L. Kinibrugh, V. N. Khustalev,
S. C. Jones, M. Yu. Antipin, N. M. Tucker, T. V. Timofeeva, V.
Coropceanu, J. L. Brꢅdas, S. R. Marder, J. Am. Chem. Soc. 2006,
1
5H05754 to EN) and the Strategic Promotion of Innovative
Research, JST (to EN) from MEXT, Japan. M.H. and C.L. are
grateful to the Deutsche Forschungsgemeinschaft for sup-
porting this work (GRK 2112).
Conflict of interest
1
28, 1812 – 1817.
The authors declare no conflict of interest.
[
22] Y. Su, X. Wang, X. Zheng, Z. Zhang, Y. Song, Y. Sui, Y. Li, X.
Wang, Angew. Chem. Int. Ed. 2014, 53, 2857 – 2861; Angew.
Chem. 2014, 126, 2901 – 2905; X. Wang, Z. Zhang, Y. Song, Y. Su,
X. Wang, Chem. Commun. 2015, 51, 11822 – 11825.
Keywords: absorption · charge transfer · oligomerization ·
radicals · structure determination
[
23] E. E. Havinga, J. L. van Donger, R. A. J. Janssen, J. Cornil, J.-L.
Brꢅdas, Chem. Eur. J. 1998, 4, 1509 – 1522.
[
24] S. Rodrꢄguez Gonzꢁlez, Y. Ie, Y. Aso, J. T. Lꢂpez Navarrete, J.
Casado, J. Am. Chem. Soc. 2011, 133, 16350 – 16353.
2
+
[
1] R. E. Martin, F. Diederich, Angew. Chem. Int. Ed. 1999, 38,
350 – 1377; Angew. Chem. 1999, 111, 1440 – 1469; S. Kubatkin,
[25] CCDC 1515237 – 1515242 [DA(COPV1-OCH ) ] contain the
3
1
supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge
Crystallographic Data Centre.
A. Danilov, M. Hjort, J. Cornil, J.-L. Bredas, N. Stuhr-Hansen, P.
Hedegard, T. Bjørnholm, Nature 2003, 425, 698 – 701; V. K.
Praveen, C. Ranjith, E. Bandini, A. Ajayaghosh, N. Armaroli,
Chem. Soc. Rev. 2014, 43, 4222 – 4242.
[
2] X. Zhu, C. Mitsui, H. Tsuji, E. Nakamura, J. Am. Chem. Soc.
Manuscript received: November 8, 2016
2009, 131, 13596 – 13597.
Final Article published: && &&, &&&&
Angew. Chem. Int. Ed. 2017, 56, 1 – 6
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
5
These are not the final page numbers!

Angewandte
Communications
Chemie
Communications
Charge Transfer
Bridge the gap: Electronic communica-
tion (charge transfer and spin coupling)
over long covalent distances are achieved
by using “pole-like” carbon-bridges
between oligophenylene and vinylene
units. This communication is demon-
strated by using bis(triarylamine)-substi-
tuted carbon-bridged oligo(para-phenyl-
enevinylene) cores in their radical cation
and dication states.
P. M. Burrezo, N.-T. Lin, K. Nakabayashi,
S.-i. Ohkoshi, E. M. Calzado, P. G. Boj,
M. A. Dꢁaz Garcꢁa, C. Franco, C. Rovira,
J. Veciana, M. Moos, C. Lambert,
J. T. Lꢂpez Navarrete, H. Tsuji,*
E. Nakamura,* J. Casado*
&&& — &&&
Bis(Aminoaryl) Carbon-Bridged
Oligo(phenylenevinylene)s Expand the
Limits of Electronic Couplings
6
www.angewandte.org
ꢀ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2017, 56, 1 – 6
These are not the final page numbers!