ipso-Arylative Ring-Opening Polymerization as a Route to Electron-Deficient Conjugated Polymers

Article abstract of DOI:10.1002/anie.201809610

ipso-Arylative ring-opening polymerization of 2-bromo-8-aryl-8H-indeno[2,1-b]thiophen-8-ol monomers proceeds to M_n up to 9 kg mol^?1 with conversion of the monomer diarylcarbinol groups to pendent conjugated aroylphenyl side chains (2

Full text of DOI:10.1002/anie.201809610

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: ipso-Arylative Ring-opening Polymerization as a Route to
Electron-deficient Conjugated Polymers
Authors: Feng-Yang Shih, Deokkyu Choi, Qin Wu, Chang-Yong Nam,
and Robert B. Grubbs
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.201809610
Angew. Chem. 10.1002/ange.201809610
Link to VoR: http://dx.doi.org/10.1002/anie.201809610
http://dx.doi.org/10.1002/ange.201809610

10.1002/anie.201809610
Angewandte Chemie International Edition
COMMUNICATION
ipso-Arylative Ring-opening Polymerization as a Route to
Electron-deficient Conjugated Polymers
Feng-Yang Shih,[a] Deokkyu Choi,[a] Qin Wu,ꢀbꢁ Chang-Yong Nam,ꢀbꢁ Robert. B. Grubbs*,[a]
Abstract: ipso-Arylative ring-opening polymerization of 2-bromo-8-
Previous ring-opening arylations
Ph OH
aryl-8H-indeno[2,1-b]thiophen-8-ol monomers proceeds to Mn up to 9
kg/mol with conversion of the monomer diarylcarbinol groups to
pendent conjugated aroylphenyl side chains (2-benzoylphenyl or 2-
(4-hexylbenzoyl)phenyl) that influence the optical and electronic
properties of the resulting polythiophenes. Poly(3-(2-(4-
hexylbenzoyl)phenyl)thiophene) was found to have lower frontier
orbital energy levels (HOMO/LUMO = -5.9/-4.0 eV) than poly(3-
hexylthiophene) due to the electron-withdrawing ability of the aryl
ketone side chains. The electron mobility (~2×10-3 cm2 V-1 s-1) for
poly(3-(2-(4-hexylbenzoyl)phenyl)thiophene) was found to be
significantly higher than the hole mobility (~8×10-6 cm2 V-1 s-1), which
suggests such polymers are candidates for n-type organic
semiconductors. Density functional theory calculations suggest that
backbone distortion resulting from side-chain steric interactions could
be a key factor influencing charge mobilities.
OH
Ar
Ar
O
S
S
Pd(OAc)2, PCy3
Br
ArBr
[Pd]
Cs2CO3, 140 °C
o-xylene
n
O
Ar
P1: Ar = -Ph
Terao 2001
Ph
O
1: Ar = -Ph
2: Ar = -C6H4C6H13
tBu
P2: Ar = -C6H4C6H13
ArX
tBu
[Pd]
Ar
OH
Ph
Ph
Previous ipso-arylative polymerization
Nishimura 1999
Ziadi 2012
Ph Ph
S
S
Pd(OAc)2, PCy3
Br
OH
OMe
OMe
OH
CH3
Cs2CO3, 140 °C
o-xylene
n
ArX
[Pd]
Ar
O
C6H13
C6H13
3
P3HT
Mn to 20 kg/mol
Ð 1.4-2.2
CH3
Shih 2018
Chtchemelinine 2011
Scheme 1. Asterisks indicate end-group variability. References: Shih 2018,[15]
Terao 2001,[10b] Nishimura 1999,[13a] Ziadi 2012,[13b] Chtchemelinine 2011.[13c]
In a previous study, we investigated the ipso-arylative cross-
Ring-opening polymerization (ROP) is a powerful method for the
preparation of functionalized polymers. The majority of ROP
methods use heterocyclic monomers (ethers,[1] lactones,[2]
lactams,[3] oxazolines[4]) and ionic polymerization methods,[5] with
coupling
polymerization
of
5-bromo-4-hexylthiophen-2-
yl)diphenylmethanol (3) to prepare poly(3-hexylthiophene)
(P3HT) (Scheme 1).[15] While P3HT with Mn values of up to 20
kg/mol could be prepared, molecular weights were ultimately
limited by end group loss over the course of the polymerization
and dispersity values were typical of a step growth polymerization
(Đ 1.4-2.2).[15] An additional limitation, common to all ipso-
arylation reactions, was the generation of one equivalent of
ketone (benzophenone) for each monomer coupling step.
a
few important exceptions, including radical ring-opening
polymerization,[6] ring-opening metathesis polymerization,[7] and
other metal-catalyzed ROP processes involving allyl-Pd
complexes or Pt-catalyzed opening of silaferrocenophanes.[8]
While Pd-catalyzed aryl-aryl coupling reactions, particularly
Stille and Suzuki-Miyaura reactions,[9] have been widely used for
the preparation of conjugated polymers, these methods are not
easily converted to ring-opening methods. ipso-Arylative coupling
methods[10] that involve diaryl[11] or dialkylcarbinol[12] leaving
groups generate ketone by-products that, with appropriate
monomer design, can remain bound to the polymer backbone.
With a conjugated polymer backbone, this strategy has the benefit
of enabling the electron-withdrawing ketone moiety to directly
influence the electronic properties of the polymer. While several
examples of ring-opening arylative cross-coupling reactions have
been reported with small molecules, including the ipso-arylation
of 9-phenylfluoren-9-ol with phenyl bromide,[10b] as well as ring-
opening arylations of cyclobutanols[13] and norbornenols,[14] there
are no reports of polymerization by these methods (Scheme 1).
To side-step this latter problem and, in the process, examine
the effect of electron-withdrawing aroylphenyl side chains on the
optical and electronic properties of the polythiophene backbone,
we have designed two monomers, 2-bromo-8-phenyl-8H-
indeno[2,1-b]thiophen-8-ol (1) and 2-bromo-8-(4-hexylphenyl)-
8H-indeno[2,1-b]thiophen-8-ol (2), capable of undergoing ipso-
arylative ring-opening cross-coupling polymerization to result in
polymers P1 and P2 in which the aroylphenyl group that results
from carbinol extrusion is retained as an electron-withdrawing
moiety conjugated to the polythiophene backbone (Scheme 1).
ROP of monomer 1 was carried out by ipso-arylative cross-
coupling under conditions that were previously found to be
effective for the polymerization of 5-bromo-4-hexylthiophen-2-
yl)diphenylmethanol (Scheme 1).[15] Monomer 1 (0.1 M) was
heated with Pd(OAc)2 (3 mM), PCy3 (6 mM), and Cs2CO3 (0.15 M)
in o-xylene at 140 °C for 48 h. Over the course of the
polymerization, formation of an insoluble red powder was
observed. After sequential washing of the isolated solid with
acetone and THF, the fraction of P1 that was isolated by Soxhlet
extraction with CHCl3 was partially dissolved in THF, and found
by SEC to have a moderate molecular weight (Mn = 10 kg/mol vs
[a]
[b]
Dr. F.Y. Shih, D. Choi, and Prof. R. B. Grubbs
Chemistry department, Stony Brook University
Stony Brook, NY 11794 (USA)
E-mail: robert.grubbs@stonybrook.edu
Dr. Q. Wu and Dr. C.Y. Nam
PS standards) and
a dispersity typical of a step-growth
Center for Functional Nanomaterials
Brookhaven National Laboratory
Upton, NY 11973 (USA)
polymerization (Đ = 2.0). The relatively low yield (49% for the
CHCl3 fraction) and formation of insoluble material suggest that
the polymerization proceeds to a higher molecular weight than is
Supporting information for this article is given via a link at the end of
the document.
This article is protected by copyright. All rights reserved.

10.1002/anie.201809610
Angewandte Chemie International Edition
COMMUNICATION
Table 1. Polymerization conditions and characterization data for polymers P2.[a]
[b]
Mn
Yield
(%)[c]
Monomer
(conc., M)
[Pd(OAc)2]
(mM)
t
T
(°C)
(kg/
mol)
Đ [b]
(h)
P2a
P2b
P2c
2 (0.5)
2 (0.5)
2 (0.1)
3
5
5
48
48
72
140
140
170
9.0
4.9
7.0
2.0
1.8
1.6
76
67
58
[a] [1] = 0.1 M or [2] = 0.1 or 0.5 M, [Pd(OAc)2] = 3 or 5 mM, [PCy3] = [Pd(OAc)2]
× 2, and Cs2CO3 (0.15 M) heated in o-xylene at 140 or 170 °C for 48-72 h; [b]
number-average molecular weight (Mn) and dispersity (Đ) of polymers in
chloroform fractions were estimated by SEC in THF with polystyrene standards;
[c] yield of the CHCl3 fraction based on 100% conversion.
apparent by SEC, but further characterization and thin-film
processing of P1 was difficult because of the poor solubility.
To increase solubility, polymerization of monomer 2, an
analog of monomer 1 with an n-hexyl side-chain in the para-
position of the phenyl group, was investigated under similar
conditions and found to proceed without precipitation to afford P2
as a red powder after Soxhlet purification (washing with acetone
followed by isolation with CHCl3) with a high yield of the CHCl3-
soluble fraction (76%, Table 1). P2 showed significantly higher
solubility in THF, CHCl3, and o-dichlorobenzene than P1. P2a,
prepared with a 3 mM concentration of Pd(OAc)2, showed a
comparable molecular weight (Mn = 9.0 kg/mol vs PS standards)
and dispersity (Đ = 2.0) to P1 by SEC (Table 1). Higher catalyst
loading (5 mM) resulted in a lower molecular weight (P2b, Mn =
4.9 kg/mol) and a lower yield (67%) (Table 1), which suggests that
the catalyst is playing a role in the loss of active end-groups, as
has been observed previously for ipso-arylative polymerization of
monomer 3.[15] Higher temperature (170 °C) with lower [2] (0.1 M)
resulted in slightly lower molecular weight (P2c, Mn = 7 kg/mol)
and lower yield (58%) than P2a, suggesting the occurrence of
catalyst decomposition or other side reactions.
Figure 1. UV-Vis absorbance spectra of (A) P1 in CHCl3 (0.02 mg/mL) (gray)
and thin film (cast on glass from 0.5 mg/mL CHCl3 solution) (black), and (B) P2a
in solution (gray) and thin film (black).
Absorbance spectra for P1 and P2a were acquired in solution
(0.02 mg/ml, CHCl3) and in thin films (glass, 0.5 mg/ml CHCl3
solution) (Figure 1). For both P1 and P2a, λmax in thin films shifted
to the red from λmax in solution (0.24 eV, from 480 to 530 nm, for
P1; 0.30 eV, from 430 to 480 nm, for P2a) as a result of increased
intermolecular interactions in the thin film (Figure 1). The thin-film
optical band gaps were estimated as 2.01 eV for P1 (λonset = 620
nm) and 2.17 eV for P2a (λonset = 570 nm).
The higher solubility of polymer P2 allowed characterization
by 1H NMR. In CD2Cl2, peaks corresponding to the arylene (7.0-
7.5 ppm), thienyl (6.51 ppm), and n-hexyl side chains (2.6, 1.5,
1.3, and 0.87 ppm) were observed (Figure S1). IR spectra showed
a peak at 1660 cm-1 for both P1 and P2a corresponding to side-
chain carbonyl groups and, for P2a, a peak at 2800-3000 cm-1
corresponding to alkyl C-H stretching vibrations in the n-hexyl
groups (Figure S2).
Electrochemical band gaps for P1 (2.09 eV; Eox. onset = 0.58 V;
Ered. onset = -1.25 V) and P2 (2.18 eV; Eox. onset = 0.82 V; Ered. onset
=
MALDI-TOF MS analysis showed both P1 and P2 to have a
primary series of peaks with a mass difference between peaks
that corresponds to the mass of the repeating units (262.3 g/mol
for P1 and 346.5 g/mol for P2) and m/z values suggesting chains
lacking a terminal bromide (Figure S4), as a result of either
protodehalogenation or reductive coupling of thienyl halide chain
ends (Figure S5), as has previously been observed for the ipso-
arylative polymerization of monomer 3. Both P1 and P2 also show
minor series of peaks assigned to cationization through loss of
hydroxide and transfer of phenyl/4-hexylphenyl groups to chain
ends (Figure S4-S5).
-1.08 V) measured by cyclic voltammetry were found to be in good
agreement with the optical band gaps (Figure 2). The larger
bandgap for P2a may result from backbone distortion induced by
the hexyl side-chains.[16] The aroylphenyl side-chains lead to
significantly lower frontier molecular orbital (FMO) energy levels
for P1 (HOMO = -5.68 eV and LUMO = -3.85 eV) and P2a (HOMO
= -5.92 eV and LUMO = -4.02 eV) as compared to those which
have been reported for P3HT (HOMO = -4.75 eV and LUMO = -
2.83 eV) (Table 2).[17]
This article is protected by copyright. All rights reserved.

10.1002/anie.201809610
Angewandte Chemie International Edition
COMMUNICATION
consistent with the larger red shift observed in the absorbance
spectrum of P2a compared with P1 (Figure 1).[21]
The low LUMO energy of P2 suggested it could also serve as
an n-type semiconducting polymer. The electron mobility (μe) of
P2a was measured in devices with an FTO/TiO2/Polymer/Al
architecture, in which TiO2 was used as ohmic contact (Figure
S7).[22] The μe for P2a calculated using the SCLC model was
~2×10-3 cm2 V-1 s-1, which is significantly higher than μe values
reported for P3HT (~2.1×10-9 cm2 V-1 s-1),[23] and comparable to
μe values reported for organic non-fullerene molecules and
polymers used as acceptors in OPV devices with high efficiencies
(PCE from 6-11% for μe from 1-3 ×10-3 cm2 V-1 s-1).[24]
Density functional theory (DFT) calculations (B3LYP/6-
31G(d)) were carried out on a model P1 octamer to confirm the
effect of the aroylphenyl side chains on the observed properties
of P1 and P2. The S-C-C-S dihedral angles between neighboring
thienyl units were examined and compared to those in P3HT
calculated at the same level.[25] In P1, these angles were found to
range from 133-142°, vs 142-160° in P3HT and 180° in a perfectly
trans-planar structure. Thus the 2-benzoylphenyl side chains in
P1 appear to decrease planarity of the polythiophene backbone
and reduce the conjugation length of the polymer, which would be
consistent with the lower μh measured for P1 as compared to
P3HT. With time-dependent DFT and a polarizable continuum
model of the chloroform solvent, the lowest singlet excitation of
the P1 octamer model was calculated to be 2.50 eV (495 nm) with
a large oscillator strength (1.5849), which is in good agreement
with the experimental λmax measured for P1 (~500 nm) in
chloroform (Figure 1a). The calculated natural transition orbitals
(NTO)[26] that are used to approximate the hole (i.e., HOMO) and
electron (i.e., LUMO) of this excitation show that, while the hole is
essentially confined to the backbone, the electron is delocalized
to the side-chain aromatic rings (Figure 3). Such delocalization
would enhance inter-chain interactions due to increased orbital
overlap and reduce trapping of electrons on a single chain, which
supports the higher electron mobility measured experimentally.
Figure 2. Cyclic voltammograms of (A) P1 and (B) P2a in Bu4NOH (0.1
M)/CH3CN. Polymer in CHCl3 (1 mg/ml) were drop-cast on a carbon glass
working electrode .Conducting electrode: Au wire; Reference electrode: Pt wire
in AgNO3 (0.01 M)/Bu4NOH (0.1 M)/ CH3CN.
Table 2. Optical and electronic properties of P1 and P2a
λonset HOMO/
[e]
[f]
Eg,opt
Eg,elec μh
μe
(cm2 V-1 s-1)
(nm) LUMO
(eV)[c] (eV) [d] (cm2 V-1 s-1)
[a]
(eV) [b]
-5.68/
618
P1
2.01
2.17
2.09
2.18
7.9 (± 2.0) × 10-7 Not measured
7.8 (± 1.3) × 10-6 2 (± 1.6) × 10-3
-3.85
-5.92/
P2a 571
-4.02
[a] Onset wavelength of absorbance in spectrum; [b] HOMO = -(5.1 + Eoxidation
onset) eV; LUMO = -(5.1 + Ereduction onset) eV; [c] Optical bandgap Eg,opt = 1240
eVꞏnm/λonset; [d] Electrochemical bandgap Eg,elec= -(LUMO-HOMO); [e] Hole
mobility (μh) averaged over
8 measurements with standard deviation in
parentheses calculated from SCLC model. [f] Electron mobility (μe) averaged
over 6 measurements with standard deviation in parentheses calculated from
SCLC model.
Figure 3. Natural transition orbitals that represent the hole (left) and electron
(right) of the lowest singlet transition in a model P1 octamer.
Hole mobilities (μh) for each polymer were measured by
analyzing current density-voltage (J–V) characteristics of hole-
only ohmic devices with the space-charge-limited current (SCLC)
model.[18] For hole mobility measurements, SCLC devices were
built in an ITO/MoOx/polymer/MoOx/Au architecture (Figure
S6).[19] P1 showed a hole mobility (µh) of 8 × 10-7 cm2 V-1 s-1 (Figure
S8), while µh for P2a was found to be an order of magnitude
higher (8 × 10-6 cm2 V-1 s-1), though still two orders of magnitude
lower than µh values reported for P3HT (1.1 × 10-4 cm2 V-1 s-1 for
Mn = 9.7 kg/mol).[20] In comparing P1 and P2, the higher hole
mobility observed for P2 likely results from its higher solubility,
which results in films with more effective interchain π-stacking
These results show that ipso-arylative ring-opening
polymerization of 2-bromo-8-aryl-8H-indeno[2,1-b]thiophen-8-ol
monomers 1 and 2 can proceed with retention of organic leaving
groups that can significantly influence polymer electronic and
optical properties. While the side reactions typical of ipso-arylative
polymerization conditions identified to date and the steric factors
introduced by the monomer structural requirements appear to be
limiting factors, polymer P2 has electron mobility values and
frontier MO energy levels comparable to other n-type non-
fullerene acceptor materials that have been used in high-
performance OPV devices. Further optimization of the synthesis
of conjugated polymers bearing diarylketone substituents by ipso-
This article is protected by copyright. All rights reserved.

10.1002/anie.201809610
Angewandte Chemie International Edition
COMMUNICATION
[21]
[22]
J. Mei, Z. Bao, Chem. Mater. 2014, 26, 604-615.
arylation or other methods could enable the identification of new
S. Sandén, O. Sandberg, Q. Xu, J.-H. Smått, G. Juška, M. Lindén,
R. Österbacka, PCCP 2012, 14, 14186-14189.
M. Ahmed, I. Hummelgen, Int. J. Electroactive Mater. 2013, 1, 60-
63.
C. Yan, S. Barlow, Z. Wang, H. Yan, A. K. Y. Jen, S. R. Marder, X.
Zhan, Nat. Rev. Mater. 2018, 3, 18003.
n-type organic semiconductors for
applications.
a range of electronic
[23]
[24]
[25]
[26]
M. J. Frisch, Wallingford, CT, 2016.
R. L. Martin, The Journal of Chemical Physics 2003, 118, 4775-
4777.
Acknowledgements
This work was supported by National Science Foundation (CHE-
1506822). This research used resources of the Center for
Functional Nanomaterials, which is a U.S. DOE Office of Science
Facility, at Brookhaven National Laboratory under Contract No.
DE-SC0012704. Computational resource at the Scientific Data
and Computing Center, a component of the Computational
Science Initiative at BNL is also acknowledged. Authors thank Dr.
Bela P. Ruzsicska for assistance with MALDI-TOF MS analysis
and high- resolution mass spectroscopy, Yuchen Zhou for
assistance with device fabrication, Dr. Mingzhao Liu for
assistance with cyclic voltammetry measurement, Dr. Francis
Picart, Dr. Fang Liu, and Dr. Jim Marecek for assistance with
NMR analysis, and Gwen Wright for assistance with SEM imaging.
Keywords: conducting materials • cross-coupling • ipso-
arylative polymerization • palladium • ring-opening
polymerization
[1]
[2]
A. Sunder, R. Hanselmann, H. Frey, R. Mülhaupt, Macromolecules
1999, 32, 4240-4246.
O. Dechy-Cabaret, B. Martin-Vaca, D. Bourissou, Chem. Rev.
2004, 104, 6147-6176.
[3]
[4]
H. Hall Jr, J. Am. Chem. Soc. 1958, 80, 6404-6409.
S. Kobayashi, T. Tokuzawa, T. Saegusa, Macromolecules 1982,
15, 707-710.
[5]
[6]
J. V. Crivello, J. Lam, Macromolecules 1977, 10, 1307-1315.
a) W. J. Bailey, Z. Ni, S. R. Wu, Macromolecules 1982, 15, 711-
714; b) A. D. Asandei, I. W. Moran, J. Am. Chem. Soc. 2004, 126,
15932-15933.
[7]
[8]
[9]
a) C. W. Bielawski, R. H. Grubbs, Prog. Polym. Sci. 2007, 32, 1-
29; b) R. B. Grubbs, R. H. Grubbs, Macromolecules 2017, 50,
6979-6997.
a) M. Suzuki, A. Ii, T. Saegusa, Macromolecules 1992, 25, 7071-
7072; b) S. Kim, D. Takeuchi, K. Osakada, J. Am. Chem. Soc.
2002, 124, 762-763.
a) M. Jayakannan, J. L. J. van Dongen, R. A. J. Janssen,
Macromolecules 2001, 34, 5386-5393; b) Y. S. Park, T. S. Kale, C.
Y. Nam, D. Choi, R. B. Grubbs, Chem. Commun. 2014, 50, 7964-
7967; c) Y. S. Park, Q. Wu, C. Y. Nam, R. B. Grubbs, Angew.
Chem. Int. Ed. 2014, 53, 10691-10695.
[10]
a) Y. Terao, H. Wakui, M. Nomoto, T. Satoh, M. Miura, M. Nomura,
J. Org. Chem. 2003, 68, 5236-5243; b) Y. Terao, H. Wakui, T.
Satoh, M. Miura, M. Nomura, J. Am. Chem. Soc. 2001, 123,
10407-10408.
[11]
[12]
[13]
a) S. M. Bonesi, M. Fagnoni, A. Albini, Angew. Chem. Int. Ed.
2008, 47, 10022-10025; b) J. R. Bour, J. C. Green, V. J. Winton, J.
B. Johnson, J. Org. Chem. 2013, 78, 1665-1669.
a) S. M. Bonesi, M. Fagnoni, Chem. Eur. J. 2010, 16, 13572-
13589; b) M. Iwasaki, Y. Araki, S. Iino, Y. Nishihara, J. Org. Chem.
2015, 80, 9247-9263.
a) T. Nishimura, S. Uemura, J. Am. Chem. Soc. 1999, 121, 11010-
11011; b) A. Ziadi, R. Martin, Org. Lett. 2012, 14, 1266-1269; c) A.
Chtchemelinine, D. Rosa, A. Orellana, J. Org. Chem. 2011, 76,
9157-9162.
[14]
[15]
[16]
[17]
Y. Li, W. Yang, G. Cheng, D. Yang, J. Org. Chem. 2016, 81, 4744-
4750.
F.-Y. Shih, S. Tian, N. Gallagher, Y. S. Park, R. B. B. Grubbs,
Polym. Chem. 2018, 9, 3223-3231.
B. Friedel, C. R. McNeill, N. C. Greenham, Chem. Mater. 2010, 22,
3389-3398.
C. J. Shi, Y. Yao, Y. Yang, Q. B. Pei, J. Am. Chem. Soc. 2006,
128, 8980-8986.
[18]
[19]
C. Y. Nam, J. Phys. Chem. C 2012, 116, 23951-23956.
A. Buckley, D. Pickup, C. Yates, Y. Zhao, D. Lidzey, J. Appl. Phys.
2011, 109, 084509.
[20]
C. Goh, R. J. Kline, M. D. McGehee, E. N. Kadnikova, J. M.
Fréchet, Appl. Phys. Lett. 2005, 86, 122110.
This article is protected by copyright. All rights reserved.

10.1002/anie.201809610
Angewandte Chemie International Edition
COMMUNICATION
Entry for the Table of Contents (Please choose one layout)
Layout 1:
COMMUNICATION
Dr. F.Y. Shih, D. Choi, Dr. Q. Wu and
Dr. C.Y. Nam
Prof. R. B. Grubbs*
Page No. – Page No.
ipso-Arylative Ring-opening
Polymerization as a Route to Electron-
deficient Conjugated Polymers
Dangling modifiers. ipso-Arylative cross-coupling polymerization leads to n-type
polythiophenes with pendent electron-withdrawing diarylketone groups.
This article is protected by copyright. All rights reserved.