Templated Synthesis of End-Functionalized Graphene Nanoribbons through Living Ring-Opening Alkyne Metathesis Polymerization

Article abstract of DOI:10.1021/jacs.9b01805

Atomically precise bottom-up synthesized graphene nanoribbons (GNRs) are promising candidates for next-generation electronic materials. The incorporation of these highly tunable semiconductors into complex device architectures requires the development of

Full text of DOI:10.1021/jacs.9b01805

Subscriber access provided by UNIV AUTONOMA DE COAHUILA UADEC
Article
Templated Synthesis of End-Functionalized Graphene Nanoribbons
Through Living Ring-Opening Alkyne Metathesis Polymerization
Stephen von Kugelgen, Ilya Piskun, James H. Griffin, Christopher
T. Eckdahl, Nanette N. Jarenwattananon, and Felix R. Fischer
J. Am. Chem. Soc., Just Accepted Manuscript • Publication Date (Web): 24 Jun 2019
Downloaded from http://pubs.acs.org on June 24, 2019
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a service to the research community to expedite the dissemination
of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in
full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully
peer reviewed, but should not be considered the official version of record. They are citable by the
Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore,
the “Just Accepted” Web site may not include all articles that will be published in the journal. After
a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web
site and published as an ASAP article. Note that technical editing may introduce minor changes
to the manuscript text and/or graphics which could affect content, and all legal disclaimers and
ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or
consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W.,
Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 9
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
Templated Synthesis of End-Functionalized Graphene Nanoribbons
Through Living Ring-Opening Alkyne Metathesis Polymerization
Stephen von Kugelgen,† Ilya Piskun,† James H. Griffin,† Christopher T. Eckdahl,† Nanette N. Jarenwattananon†
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
and Felix R. Fischer† *
∫|
†Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States
∫Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
|Kavli Energy Nanosciences Institute at the University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley,
California 94720, United States
ABSTRACT:
Atomically precise bottom-up synthesized graphene nanoribbons (GNRs) are promising candidates for next-generation elec-
tronic materials. The incorporation of these highly tunable semiconductors into complex device architectures requires the development of
synthetic tools that provide control over the absolute length, the sequence, and the end-groups of GNRs. Here, we report the living chain-
growth synthesis of chevron-type GNRs (cGNRs) templated by a poly-(arylene ethynylene) precursor prepared through ring-opening alkyne
metathesis polymerization (ROAMP). The strained triple bonds of a macrocyclic monomer serve both as the site of polymerization and the
reaction center for an annulation reaction that laterally extends the conjugated backbone to give cGNRs with predetermined lengths and end-
groups. The structural control provided by a living polymer-templated synthesis of GNRs paves the way for their future integration into hierar-
chical assemblies, sequence-defined heterojunctions, and well-defined single-GNR transistors via block copolymer templates.
a single GNR are desired.
INTRODUCTION
The difficulty of assembling GNR heterojunctions is inherent to the
techniques used to assemble polymeric GNR precursors, which to
date have exclusively relied on step-growth polymerizations.18 From
a polymer perspective, a GNR heterojunction is analogous to the
junction unit of a block copolymer; the logical solution to this statis-
tical challenge is to prepare GNRs using a controlled, ideally living,
(co)polymerization.2 Living ring-opening metathesis polymeriza-
tion (ROMP) has revolutionized the synthesis of precision poly-
meric materials and enabled ready access to polymers with control
of sequence,19,20 topology,21,22 stereoregularity,23 and self-assem-
bly.24,25 ROMP has become a valuable tool in polymer synthesis in
large part due to its tolerance of complex, polyfunctional side chains.
However the unsaturated polymer backbones prepared by ROMP
are also primed for post-polymerization elaboration, though this is a
far less common strategy.26–28 In the context of GNR synthesis, ole-
fins are undoubtedly useful polyarylene building blocks, but alkynes
are particularly valuable due to their redox equivalence to aromatic
sp2 carbons.29–33 Ring-opening alkyne metathesis polymerization
(ROAMP) therefore stands as a privileged technique to prepare al-
kyne-containing block copolymer precursors amenable to further
elaboration of the carbon-carbon triple bonds into controlled GNR
heterostructures.
Graphene nanoribbons (GNRs) straddle the border between linear,
1D ladder polymers and extended 2D graphene. While they share a
host of the attractive physical and electronic properties of bulk 2D
graphene, quantum confinement along one dimension opens a tune-
able bandgap that positions GNRs as privileged candidates for next-
generation electronic devices. The extremely small (< 2 nm) lateral
dimensions, the control of translational symmetry, and the chemical
fidelity of edge structures required to manifest these quantum effects
in a controlled and reproducible materials system defy traditional
top-down synthetic approaches.1 Bottom-up approaches instead ac-
cess these narrow strips of graphene from molecular precursors,
which allows organic and polymer chemistry to precisely engineer
the location of every atom in each repeat unit at the sub-nanometer
scale.2 This strategy has enabled rapid advances in our understand-
ing of the role of nanoribbon width,3–5 dopant atom incorporation,6–
9
crystallographic symmetry,10,11 and topological phenomena12,13 in
determining their electronic structure. However, the interface of two
or more GNRs of dissimilar electronic band structures fused along a
well-defined interface forms the basis of the most promising GNR
device architectures.14,15 While the synthesis ofthese heterojunctions
can be facilitated by hierarchical growth strategies or by scanning
probe tip manipulation, the former still yields a statistical distribu-
tion of junction interfaces within a single ribbon while the through-
put of the latter is extremely limited.16,17 These tools have proven ad-
equate when small populations of single-junction GNRs are needed
to study their electronic interfaces by single molecule spectroscopy,
yet transistor device fabrication demands both high structural fidel-
ity and throughput for realistic device yields. These problems are
only magnified when multiple predetermined heterojunctions along
Herein, we describe the development of a ROAMP approach to the
living, chain-growth synthesis of polymeric GNR precursors.
ROAMP of the macrocylic diyne monomer 1,2,5,6(1,3)-tetra-
1
benzenacyclooctaphane-3,7-diyne ( ) initiated by a highly selective
t
2
Mo pincer complex [pTolCºMo(ONO)O Bu] ( ) and terminated
by metathesis with a functional ynamine gives end-functionalized
1
1
poly- (Scheme 1). The alkynes of poly- can be exhaustively
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 2 of 9
functionalized by inverse electron demand Diels-Alder reactions
and the resulting poly-phenylene subsequently cyclodehydrogen-
cGNR
pare GNRs from living precursor polymers opens up the possibility
for precision synthesis of higher order GNR structures and lays the
foundation for the programmable synthesis of single GNR transistor
devices featuring multiple controlled heterojunctions.
elevated temperatures. Exhaustive screening of polymerization con-
ditions revealed that at T > 60 ºC all previously reported ROAMP
catalysts were unable to discriminate between the strained alkynes
1
2
3
4
5
6
7
8
ated to give fully graphitized
s (Figure 2). The ability to pre-
1
in and the unstrained alkynes in the growing polymer backbone
leading to stochastic chain-transfer and -termination processes.22,35–
39
Efforts to increase the kinetic selectivity by lowering the reaction
temperature or monomer concentration slowed the rate of polymer-
1
ization to a crawl; at [ ] of 2 mM, a 10% loading of the reported
RESULTS AND DISCUSSION
ROAMP catalyst [p-TolCºMo(ONO)(OR)]•KOR (R
=
CCH3(CF3)2)38 gave an initial turnover frequency of < 2 d–1 at 24 ºC.
In either case, short oligomers and cyclic polymers dominated the
product distribution. In contrast, the more electron-rich molyb-
A scalable, chromatography-free synthesis of the ring-strained mon-
9
34
1
omer 1,2,5,6(1,3)-tetrabenzenacyclooctaphane-3,7-diyne ( ) is
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
depicted in Figure 1A. Suzuki cross-coupling of (3-(methoxycar-
2
denum pincer complex featuring a tert-butoxide supporting ligand
3
bonyl)phenyl)boronic
acid
( )
with
1-bromo-3-
1
shows superb selectivity for the strained alkynes in giving access to
linear poly- in high yield. SEC analysis reveals that samples of poly-
4
((phenylsulfonyl)methyl)benzene ( ) yields the intermediate
1
5
5
biaryl . Dimerization of under pseudo-high-dilution conditions
1
2
prepared with ROAMP catalyst exhibit narrow molecular weight
6
favour the macrocyclization to bis(α-ketosulfone) . Desulfonyla-
tion under mild photoredox catalysis cleanly yields diketone . The
distributions (Đ = 1.2, Figure 2A) and Mn that scale linearly with
monomer loading and conversion, consistent with a living chain-
growth polymerization mechanism. Matrix-assisted laser desorption
ionization time of flight mass spectrometry (MALDI-TOF MS) of
7
same reduction can be performed with zinc powder on larger scales,
albeit at the cost of a slight decrease in yield (see Supporting Infor-
7
mation). Triflation of the enolate of followed by elimination gives
1a
poly- (Figure 2B) shows a family of peaks separated by integer re-
1
access to the ring-strained macrocylic dialkyne in 33% overall yield
from . Single crystals suitable for X-ray analysis were grown from a
saturated benzene solution. The two molecules found in the asym-
4
peat units of the monomer mass (Dm/z = 352 u). We thus conclude
2
1
that ROAMP catalyst selectively reacts with strained alkynes in
over the unstrained triple bonds in the growing polymer backbone,
effectively preventing undesired chain-transfer processes that would
lead to cyclic polymers, fractional numbers of monomer units in the
growing polymer chain, and a broadening of the molecular weight
distribution. Taking advantage of selective chain-transfer reagents
metric unit are depicted in Figure 1B. The average C–CºC bond an-
1
gle of the alkynes is 160.1(6)º, marking as the least angle-strained
alkyne monomer to be polymerized by ROAMP to date. The nearly
planar conformation adopted by the macrocycle reflects a small
amount of torsional strain around the biaryl C–C bonds as well (di-
hedral angle ~16.2(6)º, Figure 1B).
8 40
, the living polymer chain ends can be ter-
derived from ynamine
minated with functional groups to give end-functionalized polymers.
NMR end-group analysis and MALDI-TOF MS confirm the incor-
poration of a single nitrophenyl group per polymer chain (Support-
ing Information Figure S1).
1
The strained monomer is only sparingly soluble in noncoordinat-
ing, aprotic solvents compatible with molybdenum(VI)-based
ROAMP catalysts. Concentrated solutions (>5 mM) required for an
efficient chain-growth polymerization could only be prepared at
Figure 1. Synthesis and X-ray crystal structure of 1,2,5,6(1,3)-tetrabenzenacyclooctaphane-3,7-diyne (1) and ROAMP catalyst 2. A. Major steps
include Suzuki coupling, high-dilution macrocyclization, photoredox desulfonylation, and triflation/elimination to give . B. Single X-ray crystal struc-
1
ture of
1
. C. Single X-ray crystal structure of 2•tBuOH. Thermal ellipsoids are drawn at the 50% probability level. Colour coding: C (gray), H (white),
O (red), N (blue), Mo (turquoise). Hydrogen atoms attached to carbon in 2•tBuOH and ligand disorder are omitted for clarity.
ACS Paragon Plus Environment

Page 3 of 9
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
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
Scheme 1. Ring-opening alkyne metathesis polymerization of 1 and post-polymerization functionalization to give ROAMP-cGNR.
1
2
8
1
9
ROAMP of with at 80 ºC, followed by termination with at 55 ºC gives end-functionalized poly- . Diels-Alder benzannulation with under
10 cGNR
microwave irradiation leads to poly- . Oxidative cyclodehydrogenation yields the fully graphitized ROAMP-
.
-1
With the Mn, Đ, and end groups of poly controlled by ROAMP,
resulting extended cGNR backbone. Initial solution-state 13C-NMR
experiments showed that unfunctionalized alkynes can no longer be
we turned to the lateral extension of the alkynes to yield the charac-
teristic polyphenylene backbone of a cGNR. We herein relied on the
inverse-electron demand Diels-Alder reaction between internal al-
kynes and 2,3,4,5-tetraarylcyclopentadienones, a robust method
commonly used in polyarylene synthesis.32 Lateral extension of poly-
1
9
detected in a reaction mixture of poly- with after as little as 1 h at
250 ºC. Even with isotopically labelled substrates, the long T1 relax-
ation time of sp-hybridized carbon atoms makes the detection of
trace alkynes by 13C NMR difficult. To overcome this analytical chal-
lenge, we explored chemical methods to detect residual unreacted
1
with unsubstituted 2,3,4,5-tetraphenylcyclopentadienone leads to
10
incomplete transformations and the precipitation of an insoluble
poly-phenylene from the reaction mixture. Diels-Alder reaction of
alkynes in samples of poly- . Oxidative cleavage of residual alkynes
by e.g. ozonolysis or potassium permanganate proved unsuitable as
1
9
10
poly- with cyclopentadienone featuring dodecyl chains at 250 ºC
they slowly degrade the aromatic backbone of poly- leading to
in a microwave reactor gave the desired solubilized polyphenylene
false-positives even in poly-phenylenes prepared by Yamamoto
cross-coupling polymerizations. Instead, we turned to highly active
10
10a
(Figure 2C) shows a new
poly- . MALDI-TOF MS of poly-
family of ions exhibiting the larger repeat unit mass, with minor ion
families due to alkyl chain fragmentation. Size exclusion chromatog-
raphy (SEC, Figure 2A) reveals an apparent increase in molecular
weight along with a slight broadening of the molecular weight distri-
alkyne
[RCºMo(OC(CH3)(CF3)2)3] (R = 4-trifluoromethyphenyl) (
capable of reacting selectively with residual alkynes along the back-
10
cross-metathesis
catalysts
such
as
11
)
bone of poly- under mild conditions. Alkyne cross-metathesis of
10b
bution. SEC traces of higher molecular weight poly-
and poly-
10
samples of poly- taken after 1 h, 2 h, and 4 h (SEC traces in Figure
10c 1b 1c
derived from poly- (Mn 7 kDa) and poly- (Mn 14 kDa)
2D) in the presence of a ~100-fold excess of 1,2-bis(4-trifluoro-
methylphenyl)acetylene show a significant decrease in Mn (Figure
2E) indicative of residual unreacted alkynes in the polymer chain be-
low the detection limit of 13C NMR. A secondary advantage of our
show a characteristic shoulder. This irreproducible secondary peak
could be due to the formation of larger polymer aggregates in the
mobile phase (CHCl3).
11
depolymerization strategy is that the alkyne metathesis catalyst
Critical to any successful post-polymerization strategy is the quanti-
fication of the degree of functionalization. This is especially true for
selectively transfers a 4-trifluoromethylphenyl group to each end of
the two resulting polymer fragments that can readily be detected by
19F NMR.
1
the synthesis of cGNRs from poly- , as any structural defects in-
duced by incomplete lateral extension will lead to defects in the
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 4 of 9
1
2
3
4
5
6
7
8
9
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
Figure 2. ROAMP of 1 to poly-1 and its post-polymerization extension to poly-10. A. SEC of poly-1a and polyphenylenes poly-10a, poly-10b, and
poly-10c
.
B,C. MALDI-TOF mass spectrum of poly-1a and poly-10a exhibiting the expected repeat unit of 352 u and 1738 u respectively (minor peaks
at lower m/z are due to alkyl chain fragmentation). D. SEC of poly-10b taken at 1 h, 2 h, 4 h, and 12 h from the crude Diels-Alder reaction of poly-
with
E. Metathesis depolymerization tests to determine the extent of the Diels-Alder reaction to form poly-10b
subjected to depolymerization after Diels-Alder reaction (* denotes residual 1,2-bis(4-trifluoromethylphenyl)acetylene).
1
9
.
.
F
.
19F NMR of poly-10b samples
Figure 2F shows the 19F NMR traces of depolymerized samples of
as a black
cGNR
under Scholl reaction conditions yielded ROAMP-
poly- taken at varying reaction times. Integration of the CF3 19F
10
powder dispersible in nonpolar organic solvents. Under identical
10
conditions, a small molecule model of the repeat unit of poly-
NMR signals against an internal standard reveal an average of >25,
19, and 2.5 unreacted alkynes per polymer chain after 1 h, 2 h, and
4 h, respectively. SEC traces of samples of poly- taken after 12 h
(Figure 2D) no longer show any decrease in the Mn when subjected
to alkyne-cross metathesis depolymerization conditions (Figure
2E). 19F NMR spectra of the same samples confirm the absence of
signals that could be attributed to the incorporation of 4-trifluoro-
methylphenyl groups into the polymer chain ends as part of the al-
gave a single oxidation product consistent with the cGNRbackbone
(Supporting Information Schemes S1–S2). Solid-state 13C NMR
spectroscopy (Figure 3A) further confirms the successful ring-fu-
sion that yields the extended polycyclic aromatic backbone of
10
cGNR
s. Characteristic resonances of quaternary carbons at 139–
141 ppm are shifted to higher field following the lateral fusion of ar-
omatic rings, leaving the downfield resonance for the alkylated
GNR carbons visible at 139 ppm. A direct comparison of the Raman
11
kyne-cross metathesis with
(Figure 2F). Lastly, we used solid
cGNR
spectrum of ROAMP- s (Figure 3B) with an authentic sample
state NMR spectroscopy as an independent method to confirm the
exhaustive lateral extension of poly- with the cyclopentadienone
1
9
cGNR
of s prepared through Yamamoto step-growth polymeriza-
.
The spatial proximity of any residual alkyne carbon atoms to the or-
tho hydrogen atoms of an adjacent aromatic ring (<2.7 Å) should
enable their direct observation by cross-polarization solid-state
NMR where signal recovery is limited by the much shorter hydro-
tion shows the characteristic signatures of D (1330 cm–1) and G
(1610 cm–1) peaks along with the expected 2D (2660 cm–1), D+G
–1
cGNR
(2935 cm ) overtones. IR spectra of ROAMP-
s (Figure 3C)
show a dramatic attenuation of the aromatic C–H stretching modes,
gen T1.41 The H- C CP-SSNMR spectrum of poly-
depicted in
centered around 3050 cm–1 in poly- , following the successful oxi-
1
13
10a
10
cGNR
s
Figure 3a lacks the characteristic signatures (80–100 ppm) associ-
dative cyclodehydrogenation. UV-Vis spectra of ROAMP-
ated with alkynes. Microwave heating proved critical to the success-
show a broad visible absorption along with a shoulder centered at
42
1
cGNR
cGNR
s. Since these ROAMP- s
were prepared from a well-defined, monodisperse precursor poly-
mer (poly- ), their lengths can be controlled with high precision.
ful and exhaustive lateral extension of poly- . If the same reaction
~550 nm characteristic for
was performed in a thermal heating bath, residual alkynes could still
be detected even after >21 d. Efforts to drive the thermal reaction to
completion at temperatures >260 ºC led to the rapid decomposi-
1
9
tion of cyclopentadienone
.
10
Oxidative cyclodehydrogenation of pristine samples of poly-
ACS Paragon Plus Environment

Page 5 of 9
Journal of the American Chemical Society
CONCLUSION
1
2
3
4
5
6
7
8
We have developed a solution-based bulk synthesis of solubilized,
cGNR
end-functional
s featuring predictable and narrow molecular
weight distributions. The combination of a scalable, chromatog-
raphy-free synthesis of ring-strained diyne monomer and the ex-
quisite selectivity of a finely tuned Mo benzylidyne ROAMP cata-
lyst gives ready access to precise poly-(arylene ethynylene) tem-
plates. Lateral Diels-Alder extension of the polymer backbone fol-
lowed by exhaustive cyclodehydrogenation gives access to the fully
9
cGNR
graphitized
s. The quantitative consumption of all alkynes in
the polymer template during Diels-Alder annulation was confirmed
independently by solid state NMR and a new metathesis depoly-
merization technique that proved highly selective for and sensitive
to trace residual alkynes. Our living ring-opening alkyne metathesis
polymerization approach not only gives access to cGNRs with de-
terministic control over the ribbon length and end functionality, but
the success ofthese living polymer templates also represents the first
step toward the rational synthesis of complex intraribbon GNR het-
erojunctions from block copolymer templates.
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
EXPERIMENTAL SECTION
Materials and General Methods. Unless otherwise stated, all manipula-
tions of air and/or moisture sensitive compounds were carried out in oven-
dried glassware, under an atmosphere of Ar or N2. All solvents and reagents
were purchased from Alfa Aesar, Spectrum Chemicals, Acros Organics, TCI
America, Matrix Scientific, and Sigma-Aldrich and were used as received un-
less otherwise noted. Organic solvents were dried by passing through a col-
umn of alumina and were degassed by vigorous bubbling of N2 or Ar
through the solvent for 20 min. Diphenyl ether was purified by fractional
crystallization from the melt. Sulfolane was stirred with powdered KOH (10
%w/v) for 24 h then fractionally distilled under reduced pressure (discard-
ing the first and last 20%). Solid alkyne substrates were recrystallized under
N2 from anhydrous solvents prior to use. For air- and moisture-sensitive
NMR, deuterated solvents were stirred 24 h over 10 %w/v drying agent
(C6D6 and toluene-d8, CaH2; CDCl3, P2O5) subjected to three freeze-pump-
thaw cycles, and vacuum transferred onto activated molecular sieves. Thin
layer chromatography was performed using SiliCycle silica gel 60 Å F-254
precoated plates (0.25 mm thick) and visualized by UV absorption. All 1H,
13C{1H}, and 19F NMR spectra were recorded on Bruker AV-600, DRX-500,
or AV-500 spectrometers, and are referenced to (residual) solvent peaks
(CDCl3 1H NMR δ = 7.26 ppm, 13C NMR δ = 77.16 ppm; C6D6 1H NMR δ
= 7.16 ppm, 13C NMR δ = 128.06 ppm; pyridine-d5 1H NMR δ = 7.22 ppm,
13C NMR δ = 150.35 ppm) or hexafluorobenzene (19F NMR δ = –162.90
ppm). Solid-state 1H-13C cross polarization (CP) spectra were collected on
a Bruker AV-500 spectrometer equipped with a Bruker 4 mm 1H/X probe,
at 11 Tesla and a 13C frequency of 125.7 MHz under 10 and 12 kHz magic-
angle spinning (MAS) condition, using a contact time of 3 ms and a pulse
delay of 5 s, and proton decoupling by two-pulse phase modulation
(TPPM) at an angle of 15° and decoupling field strength of ~60 kHz. The
Hartmann-Hahn condition for CP experiments was calibrated on solid ad-
amantane, which was also used as an external 13C chemical shift reference
(methine C = 29.46 ppm). High-resolution mass spectrometry (EI) was
performed on an Autospec Premier (Waters) sector spectrometer in posi-
tive ionization mode. ESI mass spectrometry was performed on a Finnigan
LTQFT (Thermo) spectrometer. MALDI mass spectrometry was per-
formed on a Voyager-DE PRO (Applied Biosystems Voyager System 6322)
in positive mode using a matrix of dithranol. Elemental analysis (CHN) was
performed on a Perkin Elmer 2400 Series II combustion analyzer (values
are given in %). Size-exclusion chromatography (SEC) was carried out in
0.75% ethanol-stabilized chloroform on a LC/MS Agilent 1260 Infinity set
up with one guard and two Agilent Polypore 300 ´ 7.5 mm columns at 35
°C. All SEC analyses were performed on 0.2 mg/mL (or 50% of saturated, if
soluble <0.2 mg/mL) solutions of polymer in CHCl3. An injection volume
of 25 μL and a flow rate of 1 mL min–1 were used. Calibration was based on
Figure 3. Spectroscopic characterization of poly-1, poly-10,
ROAMP-cGNR, and cGNRs. A. 1H-13C CP-MAS SSNMR spectra of
poly-10 and ROAMP-cGNRs (*spinning side band) showing the up-
field shift of the fused GNR carbon core. B. Raman spectra of ROAMP-
cGNRs and an authentic sample of cGNRs prepared through Yama-
moto step-growth polymerization (514 nm excitation). C. IR (ATR) of
poly-1a, poly-10a, and ROAMP-cGNRs. D. UV-Vis spectra of
ROAMP-cGNRs and cGNRs prepared through Yamamoto step-
growth polymerization. Dispersions were prepared by sonicating 0.2
mg GNR in 2 mL NMP for 1 h and filtering through glass wool to re-
move large aggregates.
1
The chevron GNR backbone derived from poly- has a length of 1.7
nm per repeat unit.43 Oxidation of poly- , derived from ~14 kDa
1c
10c
poly- (corresponding to ~40 monomers) thus yields a bulk sam-
cGNR
ple of well-defined
featuring atomically defined end groups
and a narrow length distribution centered at 68 nm, easily long
enough to span lithographically patterned channels in FET device
architectures.
narrow dispersity polystyrene standards ranging from Mw
= 100 to
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 6 of 9
4,068,981 Da. ATR-IR spectra were obtained on a Thermo Nicolet 6700
FTIR. Raman spectra were obtained on a Renishaw inVia Qontor Raman
microscope using a 514 nm excitation. X-ray crystallography of was per-
colorless (ca. 50 mL). The product was eluted from the filter cake with
CH2Cl2 (300 mL), and concentrated on a rotary evaporator to give (220
7
1
2
3
4
5
6
7
8
1
mg, 0.57 mmol, 94%) as a pale orange solid. 1H NMR (600 MHz, CDCl3) δ
= 8.57 (s, 2H), 8.01 (s, 2H), 7.99 (d, J = 7.9 Hz, 2H), 7.78 (d, J = 7.5 Hz,
2H), 7.53 (t, J = 7.7 Hz, 2H), 7.43 – 7.32 (m, 7H), 4.39 (s, 4H) ppm.
13C{1H} NMR (151 MHz, CDCl3) δ = 196.7, 141.0, 140.5, 137.5, 136.3,
130.68 , 129.9, 129.7, 129.2, 128.1, 127.5, 126.0, 49.3 ppm. HRMS (EI)
m/z: [C28H20O2]+ calcd. 388.1463; found 338.1463.
formed on a Rigaku XtaLab equipped with a MicroMax-007HF microfocus
rotating anode source (Cu−Kα radiation), a Pilatus 200K detector, and an
Oxford Cryostream at 100 K. X-ray crystallography of 2•tBuOH was per-
formed on a Bruker APEX II QUAZAR, using a Microfocus Sealed Source
(Incoatec IμS; Mo-Kα radiation), Kappa Geometry with DX (Bruker-AXS
build) goniostat, a Bruker APEX II detector, QUAZAR multilayer mirrors
as the radiation monochromator, and Oxford Cryostream at 100 K. Crystal-
lographic data were solved with SHELXT, refined with SHELXL-2014, vis-
1,2,5,6(1,3)-Tetrabenzenacyclooctaphane-3,7-diyne
oven-dried Schlenk flask under N2 was charged with (754mg, 1.94 mmol)
( ) A 500 mL
1
7
and N-phenyltriflimide (2.1 g, 6 mmol, 3 equiv.) in dry THF (150 mL). The
reaction mixture was cooled to –78 °C and solid KHMDS (2.4 g, 12 mmol,
6 equiv.) was added in one portion. The reaction was stirred at –78 °C for 2
h and then warmed to 24 °C and quenched with H2O (40 mL). The organic
layer was separated and concentrated on a rotary evaporator. The wet resi-
due was triturated with MeOH (20 mL) to give a colorless solid, which was
extracted with hot pyridine (30 mL) and filtered. Recrystallization from pyr-
9
ualized with ORTEP, and finalized with Olex ( ) or WinGX ( ). Com-
1 2
pounds 3 44 1,2-bis(4-trifluoromethylphenyl)acetylene,46 and au-
, , ,
9 45 11 39
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
thentic samples of unsubstituted cGNRs42 were prepared according to liter-
ature procedures.
Preparation of methyl 3'-((phenylsulfonyl)methyl)-[1,1'-biphenyl]-3-
carboxylate (
and stir bar was charged with 1-bromo-3-((phenylsulfonyl)methyl)ben-
zene ( ) (4.81 g, 15.5 mmol), (3-(methoxycarbonyl)phenyl)boronic acid
) (3.46 g, 19.2 mmol, 1.25 equiv.), (PPh3)2PdCl2 (0.56 g, 0.8 mmol, 0.05
5
) A 500 mL Schlenk flask equipped with a reflux condenser
idine at 0 °C gave
1
(380 mg, 1.08 mmol, 56%) as a colorless crystalline
3
solid. The material is analytically pure, but its subsequent polymerization is
more reproducible after a second recrystallization from anhydrous THF un-
der N2. 1H NMR (600 MHz, CDCl3) δ = 8.52 (t, J = 1.7 Hz, 4H), 7.73 – 7.71
(
4
equiv.), and potassium carbonate (14.7 g, 107 mmol, 6.7 equiv.). Degassed
1:1 v/v H2O:THF (200 mL) was added and the reaction mixture stirred for
16 h under N2 at 90 °C. The reaction mixture was cooled to 24 °C and
quenched with aqueous ammonium chloride (50 mL), extracted with
EtOAc (2 ´ 25 mL), washed with water (50 mL) and brine (50 mL), dried
with MgSO4 and concentrated on a rotary evaporator. The dark brown solid
was taken up in hot EtOAc (50 mL), filtered through celite to remove insol-
uble material, and evaporated. The residue was recrystallized from minimal
(dm, J = 7.7 Hz, 4H), 7.46 (t, J = 7.7 Hz, 4H), 7.31 – 7.29 (dm, J = 7.7 Hz,
+
4H) ppm. HRMS (EI) m/z: [C28H16
]
calcd. 352.1252; found 352.1257.
Spectroscopic data are consistent with a previous report.34 Colorless blocks,
uniformly 180° twins but suitable for X-ray diffraction, were grown by slow
cooling of a saturated benzene solution from 80 to 22 °C.
1
crystallizes in
the triclinic space group P-1, a = 5.5153(2) Å, b = 15.9898(7) Å, c =
20.1319(5) Å, a = 97.836(3)°, b = 86.477(3)°, g = 89.047(4)°, Z = 2, GOF
EtOAc/hexane (1:1) and washed with hexane to give
3
(6.0 g, 15.5 mmol,
on F2 = 1.076, R indices (all data) R1 = 0.0645, wR2 = 0.1496. Solid
1
should
99%) as light brown needles. 1H NMR (500 MHz, CDCl3) δ = 8.05 (s, 1H),
8.01 (d, J = 7.8 Hz, 1H), 7.69 – 7.66 (m, 2H), 7.66 – 7.59 (m, 2H), 7.56 (d,
J = 7.8 Hz, 1H), 7.48 (t, J = 7.7 Hz, 3H), 7.37 (t, J = 7.7 Hz, 1H), 7.21 (s,
1H), 7.16 (d, J = 7.6 Hz, 1H), 4.38 (s, 2H), 3.96 (s, 3H) ppm. 13C{1H} NMR
(126 MHz, CDCl3) δ 167.0, 140.61, 140.59, 137.8, 134.0, 131.6, 130.8,
130.3, 129.7, 129.3, 129.1, 129.0, 129.0, 128.9, 128.8, 128.2, 127.7, 63.0,
52.4 ppm. HRMS (ESI-TOF) m/z: [C21H18O4S+Na]+ calcd. 389.0818;
found 389.0814.
be stored under N2 but can be handled in air; signs of decomposition (yel-
low color, reduced solubility) develop over the course of several weeks when
stored at ambient conditions.
pTolCMo[ONO]OtBu (
2
) In an N2-filled glovebox a 20 mL vial was
charged with pTolCMo(OtBu)3•(DME)0.5 (254 mg, 0.55 mmol) in dry tol-
uene (4 mL) and 6,6'-(pyridine-2,6-diyl)bis(2,4-di-tert-butylphenol)
(
H2[ONO]) (244 mg, 0.5 mmol) in dry toluene (2 mL) was added drop-
wise over 1 min. After stirring for 15 min at 24 °C the volatiles were removed
in vacuo. The brown residue was suspended in pentane (3 mL) and filtered.
The yellow solid was washed with pentane (2 ´ 1 mL) and dried at for 18 h
at 100 °C and 0.1 torr to give (256 mg, 0.34 mmol, 68%) as a yellow pow-
2
4,8-Bis(phenylsulfonyl)-1,2,5,6(1,3)-tetrabenzenacycloocta-phane-3,7-
6 5
dione ( ) An oven-dried 1 L Schlenk flask was charged under N2 with
(1.46 g, 4 mmol) in dry THF (450 mL). This mixture was added dropwise
by cannula over 8 h to a second 1 L oven-dried Schlenk flask charged under
N2 with LiHMDS (1 M in THF, 17.6 mL, 17.6 mmol, 4.4 equiv.) in dry THF
(50 mL). When the addition was complete, the reaction mixture was
quenched with saturated aqueous NH4Cl (50 mL) and water (50 mL), ex-
der. 1H NMR (500 MHz, C6D6) δ = 7.74 (d, J = 2.4 Hz, 2H), 7.29 (d, J = 2.4
Hz, 2H), 7.23 (d, J = 7.9 Hz, 2H), 6.97 (t, J = 7.9 Hz, 1H), 6.51 (d, J = 8.0
Hz, 2H), 6.37 (d, J = 8.1 Hz, 2H), 1.85 – 1.76 (m, 30H), 1.39 (s, 18H) ppm.
13C{1H} NMR (126 MHz, CDCl3) δ = 305.4, 163.0, 157.4, 142.2, 141.1,
137.9, 137.5, 137.1, 129.5, 127.8, 126.4, 125.7, 124.6, 123.0, 83.3, 35.8, 34.5,
33.0, 31.9, 30.7, 21.4 ppm. Anal. for [pTolCMo[ONO](OtBu)] calcd. C
71.31, H 7.85, N 1.85; found C 71.21, H 7.57, N 2.04. Orange blocks of
2•tBuOH suitable for X-ray analysis were grown at 24 °C by slow evapora-
tion of a pentane solution of the crude mixture of DME and tBuOH solvates
prior to desolvation. 2•tBuOH crystallizes in the monoclinic space group
P21/c, a = 15.9057(6) Å, b = 15.2617(5) Å, c = 19.1797(7) Å, b =
93.394(2)°, Z = 4, GOF on F2 = 1.077, R indices (all data) R1 = 0.0450, wR2
= 0.0966.
tracted with EtOAc (2 ´ 50 mL), washed with brine (50 mL), dried with
MgSO4 and concentrated on a rotary evaportator to a beige solid. The solid
was triturated with MeOH (20 mL), then CHCl3 (25 mL) and dried in
vacuo to give
6
(860 mg, 1.28 mmol, 64%) as a colorless solid. 1H NMR
(600 MHz, pyridine-d5) δ = 8.82 (s, 2H), 8.72 (s, 2H), 8.09 (d, J = 8.0 Hz,
2H), 7.88 (d, J = 7.3 Hz, 4H), 7.86 (d, J = 7.8 Hz, 2H), 7.81 (d, J = 7.7 Hz,
2H), 7.49 – 7.40 (m, 6H), 7.35 – 7.28 (m, 6H), 7.08 (s, 2H) ppm. 13C{1H}
NMR (151 MHz, pyridine-d5) δ = 190.1, 141.7, 140.4, 139.5, 137.0, 134.7,
132.1, 132.0, 131.9, 131.0, 130.8, 130.6, 130.5, 129.6, 129.4, 129.2, 128.2,
78.1 ppm. HRMS (ESI-TOF) m/z: [C40H28O6S2+H]+ calcd. 667.1255;
General procedure for ring-opening alkyne metathesis polymerization:
found 667.1265. The same reaction run at 400% scale (6.2 g
the same volume of solvent gave (2.15 g, 3.2 mmol) in 41% yield.
1,2,5,6(1,3)-Tetrabenzenacyclooctaphane-3,7-dione ( ) A 25 mL soda-
lime glass vial with a septum cap was charged with (400 mg, 0.6 mmol),
5
, 16 mmol) in
In an N2-filled glovebox a resealable Schlenk tube was charged with solid
1
,
6
2
, and Ph3CH (internal standard). Freshly dried toluene (0.3 mL per mg )
1
7
was added and the flask was sealed, removed from the glovebox, and con-
nected to a Schlenk line. The flask was immersed in a preheated 80 °C oil
6
Ru(bpy)3Cl2 (13 mg, 0.02 mmol, 3.3 mol%), diethyl-2,6-dimethyl-1,4-dihy-
dropyridine-3,5-dicarboxylate (334 mg, 1.32 mmol, 2.2 equiv.) in pyridine
(20 mL). The reaction mixture was degassed by sparging with N2 for 20 min
and then irradiated by blue LED light (Westinghouse 0315100 15W PAR38
Outdoor LED flood light) for 16 h. When TLC (1:2:1 EtOAc:Hex:CH2Cl2,
6 7
Rf: = 0.40, = 0.76) indicated reaction was complete, the dark red-orange
reaction mixture was poured into H2O (200 mL) and filtered through a pad
bath and stirred vigorously until all of
which point a 0.1 mL aliquot was taken, diluted with 0.5 mL dry C6D6 and
analyzed by NMR to verify the initial ratio of :Ph3CH (by integration of
the internal proton of
at 8.15 ppm, the upfield tBu groups at 1.38 ppm for
and 1.32 ppm for the initiated catalyst species, and the methine of Ph3CH
at 5.41 ppm). When >90% conversion of was reached (NMR) the reaction
temperature was lowered to 55 °C and ynamine (100 equiv. to ) in min-
1
had dissolved (typically 2–3 min) at
:
1 2
1
2
1
8
2
imal dry toluene was added. The reaction was stirred at 55 °C for 24 h and
then the catalyst was hydrolyzed by the addition of 1 M Bu4NOH solution
of celite (2 cm ´ 5 cm dia). The filter cake was washed with H2O until the
filtrate was colorless (ca. 100 mL), then with MeOH until the filtrate was
ACS Paragon Plus Environment

Page 7 of 9
Journal of the American Chemical Society
C.T.E. acknowledge support through the E3S National Science Foun-
dation REU program (ECCS-0939514). Berkeley NMR Facility is sup-
ported in part by NIH grants 1S10RR016634-01, SRR023679A, and
S10OD024998, and X-Ray Facility is supported in part by NIH Shared
Instrumentation Grant S10‐RR027172. The authors acknowledge Dr.
Hasan Celik for support with NMR acquisition, Dr. Nicholas Settineri
for assistance with X-ray analysis, and the group of Prof. R. Sarpong for
the extended use of their microwave reactor.
in MeOH (100 equiv. to
mixture was poured into 5 volumes of EtOH, filtered, washed with EtOH
and hexane and dried in vacuo to give poly- in > 90% yield.
2
) and stirred for 90 min at 80 °C. The reaction
1
2
3
4
5
6
7
8
1
General procedure for post-polymerization Diels-Alder annulation: A
0.5 mL microwave vial with a stir bar was charged under N2 with poly-1 (12
mg) and cyclopentadienone
9
(99 mg, 0.14 mmol, 2 equiv. per alkyne) in
0.45 g of dry 4:1 w/w Ph2O:sulfolane. The vial was capped and heated to
250 °C in a microwave reactor for 12 h. The vial was brought back into the
glove box, uncapped to vent the internal CO pressure, and re-capped. To
ensure complete conversion, heating was continued for 36 h at 250 °C in a
microwave reactor. After cooling to 24 °C, the reaction mixture was diluted
with toluene (1 mL), poured into EtOH (20 mL), and filtered. The solid
was re-dissolved in hexane (1 mL) and precipitated with acetone (15 mL)
REFERENCES
9
(1) Wang, X.-Y.; Narita, A.; Müllen, K. Precision Synthesis versus Bulk-
Scale Fabrication of Graphenes. Nat. Rev. Chem. 2018, 2 (1), 0100.
(2) Müllen, K. Graphene as a Target for Polymer Synthesis. In Hierar-
chical Macromolecular Structures: 60 Years after the Staudinger Nobel
Prize II; Percec, V., Ed.; Advances in Polymer Science; Springer Interna-
tional Publishing, 2013; pp 61–92.
(3) Yang, L.; Park, C.-H.; Son, Y.-W.; Cohen, M. L.; Louie, S. G. Qua-
siparticle Energies and Band Gaps in Graphene Nanoribbons. Phys. Rev.
Lett. 2007, 99 (18), 186801.
(4) Chen, Y.-C.; de Oteyza, D. G.; Pedramrazi, Z.; Chen, C.; Fischer, F.
R.; Crommie, M. F. Tuning the Band Gap of Graphene Nanoribbons Syn-
thesized from Molecular Precursors. ACS Nano 2013, 7 (7), 6123–6128.
(5) Chen, Z.; Wang, H. I.; Bilbao, N.; Teyssandier, J.; Prechtl, T.; Cavani,
N.; Tries, A.; Biagi, R.; De Renzi, V.; Feng, X.; Kläui, M.; De Feyter, S.;
Bonn, M.; Narita, A.; Müllen, K. Lateral Fusion of Chemical Vapor Depos-
ited N = 5 Armchair Graphene Nanoribbons. J. Am. Chem. Soc. 2017, 139
(28), 9483–9486.
(6) Bronner, C.; Stremlau, S.; Gille, M.; Brauße, F.; Haase, A.; Hecht, S.;
Tegeder, P. Aligning the Band Gap of Graphene Nanoribbons by Monomer
Doping. Angew. Chem. Int. Ed. 2013, 52 (16), 4422–4425.
(7) Vo, T. H.; Shekhirev, M.; Kunkel, D. A.; Orange, F.; Guinel, M. J.-F.;
Enders, A.; Sinitskii, A. Bottom-up Solution Synthesis of Narrow Nitrogen-
Doped Graphene Nanoribbons. Chem. Commun. 2014, 50 (32), 4172–
4174.
(8) Cloke, R. R.; Marangoni, T.; Nguyen, G. D.; Joshi, T.; Rizzo, D. J.;
Bronner, C.; Cao, T.; Louie, S. G.; Crommie, M. F.; Fischer, F. R. Site-Spe-
cific Substitutional Boron Doping of Semiconducting Armchair Graphene
Nanoribbons. J. Am. Chem. Soc. 2015, 137 (28), 8872–8875.
(9) Durr, R. A.; Haberer, D.; Lee, Y.-L.; Blackwell, R.; Kalayjian, A. M.;
Marangoni, T.; Ihm, J.; Louie, S. G.; Fischer, F. R. Orbitally Matched Edge-
Doping in Graphene Nanoribbons. J. Am. Chem. Soc. 2018, 140 (2), 807–
813.
(10) Ruffieux, P.; Wang, S.; Yang, B.; Sánchez-Sánchez, C.; Liu, J.;
Dienel, T.; Talirz, L.; Shinde, P.; Pignedoli, C. A.; Passerone, D.; Dumslaff,
T.; Feng, X.; Müllen, K.; Fasel, R. On-Surface Synthesis of Graphene Nano-
ribbons with Zigzag Edge Topology. Nature 2016, 531 (7595), 489–492.
(11) de Oteyza, D. G.; García-Lekue, A.; Vilas-Varela, M.; Merino-Díez,
N.; Carbonell-Sanromà, E.; Corso, M.; Vasseur, G.; Rogero, C.; Guitián, E.;
Pascual, J. I.; Ortega, J. E.; Wakayama, Y.; Peña, D. Substrate-Independent
Growth of Atomically Precise Chiral Graphene Nanoribbons. ACS Nano
2016, 10 (9), 9000–9008.
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
to remove unreacted
9
and its decomposition products. The resulting
gummy latex was centrifuged and the supernatant decanted. The pellet was
re-dissolved in hexane (1 mL) and precipitated in EtOH (20 mL), filtered,
washed with EtOH (20 mL), and dried in vacuo at 100 °C to constant
weight to give polyphenylene poly-10 (49 mg, 83%) as a colorless solid. 1H
NMR (500 MHz, CDCl3) δ =7.23 – 6.06 (m, 26H), 2.33 (s, 4H), 1.39 (s,
4H), 1.25 (s, 32H), 1.11 (s, 4H), 0.87 (s, 6H) ppm. 13C{1H} NMR (126
MHz, CDCl3, 50 mM Cr(acac)3) δ = 140.1 (br), 138.2 (br), 131.4 (br),
126.7 (br), 35.5, 32.1, 31.4, 29.9, 29.5, 29.1, 22.9, 14.3 ppm. 13C SSNMR
(1H-13C CP, 126 MHz, 12 kHz MAS) δ = 141.2, 139.2, 131.9, 126.9, 36.1,
32.7, 30.4, 23.4, 14.7 ppm.
ROAMP-cGNR A 600 mL Schlenk flask was charged under N2 with
poly-10 (62 mg) in dry CH2Cl2 (350 mL). The reaction mixture was vigor-
ously sparged with N2 for 15 min. FeCl3 (1.27 g, 7.8 mmol, 7 equiv. per H)
dissolved in 10 mL dry MeNO2 was added and the reaction mixture was
stirred at 24 °C for 84 h, continuously sparging with CH2Cl2-saturated N2.
When HCl evolution had ceased, the reaction was quenched by the addition
of MeOH (200 mL) and filtered. The black solid was washed with MeOH
(200 mL), 0.5 M HCl in 50% aqueous MeOH (100 mL), 1 M HCl (100
mL), deionized H2O (200 mL), acetone (200 mL), EtOAc (200 mL), and
hexane (100 mL). The solid was re-suspended by a 15-min sonication in
toluene (100 mL), filtered, washed with toluene (100 mL) and CH2Cl2
(200 mL). The solid was re-suspended by a 15-minute sonication in EtOH
(100 mL), filtered, washed with EtOH (100 mL) and MeOH (200 mL) and
dried in vacuo at 100 °C to constant weight to give ROAMP-cGNR (61 mg,
99%) as a black solid. 13C SSNMR (1H-13C CP, 126 MHz, 12 kHz MAS,
50%wt in KBr) δ = 138.6, 126.8, 122.5, 28.8, 13.2 ppm. Raman (powder, λ
= 514 nm) 1325 (D), 1610 (G), 2637 (2D), 2933 (D+G) cm–1
.
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the ACS Pub-
lications website at DOI: 10.1021/jacs.XXXXXXX
Figures S1 to S3, methods and instrumentation, synthetic proce-
dures for 8, pTolCMo(OtBu)3•(DME)0.5 and H2[ONO], model
studies for the regioselective cyclodehydrogenation of poly-10
,
X-ray crystallographic data (Figures S4 and S5, Tables S1 to S8),
and NMR spectra (Figures S6 to S31).
1
X-ray data for (CIF)
X-ray data for 2•tBuOH (CIF)
(12) Rizzo, D. J.; Veber, G.; Cao, T.; Bronner, C.; Chen, T.; Zhao, F.;
Rodriguez, H.; Louie, S. G.; Crommie, M. F.; Fischer, F. R. Topological
Band Engineering of Graphene Nanoribbons. Nature 2018, 560 (7717),
204–208.
(13) Gröning, O.; Wang, S.; Yao, X.; Pignedoli, C. A.; Barin, G. B.; Dan-
iels, C.; Cupo, A.; Meunier, V.; Feng, X.; Narita, A.; Müllen, K.; Ruffieux, P.;
Fasel, R. Engineering of Robust Topological Quantum Phases in Graphene
Nanoribbons. Nature 2018, 560 (7717), 209–213.
AUTHOR INFORMATION
Corresponding Author
* ffischer@berkeley.edu
(14) Goldhaber-Gordon, D.; Montemerlo, M. S.; Love, J. C.; Opiteck, G.
J.; Ellenbogen, J. C. Overview of Nanoelectronic Devices. Proc. IEEE 1997
85 (4), 521–540.
,
ACKNOWLEDGMENT
(15) Zhao, P.; Chauhan, J.; Guo, J. Computational Study of Tunneling
Transistor Based on Graphene Nanoribbon. Nano Lett. 2009, 9 (2), 684–
688.
(16) Nguyen, G. D.; Tsai, H.-Z.; Omrani, A. A.; Marangoni, T.; Wu, M.;
Rizzo, D. J.; Rodgers, G. F.; Cloke, R. R.; Durr, R. A.; Sakai, Y.; Liou, F.;
Research supported by the National Science Foundation under con-
tract number CHE-1455289 (ROAMP catalyst design and synthesis),
the Office of Naval Research MURI Program under contract number
N00014-16-1-2921 (GNR synthesis and characterization), S.v.K. and
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 8 of 9
Aikawa, A. S.; Chelikowsky, J. R.; Louie, S. G.; Fischer, F. R.; Crommie, M.
(32) Hou, I. C.-Y.; Hu, Y.; Narita, A.; Müllen, K. Diels–Alder Polymeri-
zation: A Versatile Synthetic Method toward Functional Polyphenylenes,
Ladder Polymers and Graphene Nanoribbons. Polym. J. 2018, 50 (1), 3–
20.
(33) Alabugin, I. V.; Gonzalez-Rodriguez, E. Alkyne Origami: Folding
Oligoalkynes into Polyaromatics. Acc. Chem. Res. 2018, 51 (5), 1206–
1219.
(34) Utsumi, K.; Kawase, T.; Oda, M. [2.0.2.0]Metacyclophane-1,15-
Diynes. A Potential Fragment of Double-Helical Conjugated Systems.
Chem. Lett. 2003, 32 (4), 412–413.
(35) Fischer, F. R.; Nuckolls, C. Design of Living Ring-Opening Alkyne
Metathesis. Angew. Chem. Int. Ed. 2010, 49 (40), 7257–7260.
(36) Sedbrook, D. F.; Paley, D. W.; Steigerwald, M. L.; Nuckolls, C.;
Fischer, F. R. Bidentate Phenoxides as Ideal Activating Ligands for Living
F. Atomically Precise Graphene Nanoribbon Heterojunctions from a Single
Molecular Precursor. Nat. Nanotechnol. 2017, 12 (11), 1077–1082.
(17) Bronner, C.; Durr, R. A.; Rizzo, D. J.; Lee, Y.-L.; Marangoni, T.;
Kalayjian, A. M.; Rodriguez, H.; Zhao, W.; Louie, S. G.; Fischer, F. R.;
Crommie, M. F. Hierarchical On-Surface Synthesis of Graphene Nanorib-
bon Heterojunctions. ACS Nano 2018, 12 (3), 2193–2200.
(18) Shekhirev, M.; Sinitskii, A. Solution Synthesis of Atomically Precise
Graphene Nanoribbons. Phys. Sci. Rev. 2017, 2 (5).
(19) Bielawski, C. W.; Grubbs, R. H. Living Ring-Opening Metathesis
Polymerization. Prog. Polym. Sci. 2007, 32 (1), 1–29.
(20) Chen, P. Designing Sequence Selectivity into a Ring-Opening Me-
tathesis Polymerization Catalyst. Acc. Chem. Res. 2016, 49 (5), 1052–
1060.
1
2
3
4
5
6
7
8
9
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
(21) Bielawski, C. W.; Benitez, D.; Grubbs, R. H. An “Endless” Route to
Ring-Opening Alkyne Metathesis Polymerization. Macromolecules 2012
45 (12), 5040–5044.
,
Cyclic Polymers. Science 2002, 297 (5589), 2041–2044.
(22) von Kugelgen, S.; Bellone, D. E.; Cloke, R. R.; Perkins, W. S.;
Fischer, F. R. Initiator Control of Conjugated Polymer Topology in Ring-
Opening Alkyne Metathesis Polymerization. J. Am. Chem. Soc. 2016, 138
(19), 6234–6239.
(23) Schrock, R. R. Synthesis of Stereoregular Polymers through Ring-
Opening Metathesis Polymerization. Acc. Chem. Res. 2014, 47 (8), 2457–
2466.
(37) Paley, D. W.; Sedbrook, D. F.; Decatur, J.; Fischer, F. R.; Stei-
gerwald, M. L.; Nuckolls, C. Alcohol-Promoted Ring-Opening Alkyne Me-
tathesis Polymerization. Angew. Chem. Int. Ed. 2013, 52 (17), 4591–4594.
(38) Bellone, D. E.; Bours, J.; Menke, E. H.; Fischer, F. R. Highly Selec-
tive Molybdenum ONO Pincer Complex Initiates the Living Ring-Opening
Metathesis Polymerization of Strained Alkynes with Exceptionally Low Pol-
ydispersity Indices. J. Am. Chem. Soc. 2015, 137 (2), 850–856.
(39) von Kugelgen, S.; Sifri, R.; Bellone, D.; Fischer, F. R. Regioselective
Carbyne Transfer to Ring-Opening Alkyne Metathesis Initiators Gives Ac-
cess to Telechelic Polymers. J. Am. Chem. Soc. 2017, 139 (22), 7577–7585.
(40) Jeong, H.; von Kugelgen, S.; Bellone, D.; Fischer, F. R. Regioselec-
tive Termination Reagents for Ring-Opening Alkyne Metathesis Polymeri-
zation. J. Am. Chem. Soc. 2017, 139 (43), 15509–15514.
(41) Sedláček, J.; Sokol, J.; Zedník, J.; Faukner, T.; Kubů, M.; Brus, J.;
Trhlíková, O. Homo- and Copolycyclotrimerization of Aromatic Internal
Diynes Catalyzed with Co2(CO)8: A Facile Route to Microporous Photolu-
minescent Polyphenylenes with Hyperbranched or Crosslinked Architec-
ture. Macromol. Rapid Commun. 2017, 39 (4), 1700518.
(42) Vo, T. H.; Shekhirev, M.; Kunkel, D. A.; Morton, M. D.; Berglund,
E.; Kong, L.; Wilson, P. M.; Dowben, P. A.; Enders, A.; Sinitskii, A. Large-
Scale Solution Synthesis of Narrow Graphene Nanoribbons. Nat. Com-
mun. 2014, 5, 3189.
(43) Cai, J.; Ruffieux, P.; Jaafar, R.; Bieri, M.; Braun, T.; Blankenburg, S.;
Muoth, M.; Seitsonen, A. P.; Saleh, M.; Feng, X.; Müllen, K.; Fasel, R. Atom-
ically Precise Bottom-up Fabrication of Graphene Nanoribbons. Nature
2010, 466 (7305), 470–473.
(44) Orita, A.; An, D. L.; Nakano, T.; Yaruva, J.; Ma, N.; Otera, J. Sul-
foximine Version of Double Elimination Protocol for Synthesis of Chiral
Acetylenic Cyclophanes. Chem. – Eur. J. 2002, 8 (9), 2005–2010.
(45) Jonathan, P. H.; Fukushima, T.; Kin, T.; Ogawa, A.; Aida, T. Am-
phipathic Hexa-Peri-Hexabenzocoronene Derivative. JP4005571, August
21, 2007.
(24) Xia, Y.; Olsen, B. D.; Kornfield, J. A.; Grubbs, R. H. Efficient Syn-
thesis of Narrowly Dispersed Brush Copolymers and Study of Their Assem-
blies: The Importance of Side Chain Arrangement. J. Am. Chem. Soc. 2009
131 (51), 18525–18532.
,
(25) Wright, D. B.; Touve, M. A.; Adamiak, L.; Gianneschi, N. C.
ROMPISA: Ring-Opening Metathesis Polymerization-Induced Self-As-
sembly. ACS Macro Lett. 2017, 6 (9), 925–929.
(26) Boyd, T. J.; Schrock, R. R. Sulfonation and Epoxidation of Substi-
tuted Polynorbornenes and Construction of Light-Emitting Devices. Mac-
romolecules 1999, 32 (20), 6608–6618.
(27) Meier, S.; Reisinger, H.; Haag, R.; Mecking, S.; Mülhaupt, R.;
Stelzer, F. Carbohydrate Analogue Polymers by Ring Opening Metathesis
Poymerisation (ROMP) and Subsequent Catalytic Dihydroxylation.
Chem. Commun. 2001, No. 9, 855–856.
(28) Hensbergen, J. A. van; Burford, R. P.; Lowe, A. B. Post-Functional-
ization of a ROMP Polymer Backbone via Radical Thiol-Ene Coupling
Chemistry. J. Polym. Sci. Part Polym. Chem. 2012, 51 (3), 487–492.
(29) Jordan, R. S.; Wang, Y.; McCurdy, R. D.; Yeung, M. T.; Marsh, K.
L.; Khan, S. I.; Kaner, R. B.; Rubin, Y. Synthesis of Graphene Nanoribbons
via the Topochemical Polymerization and Subsequent Aromatization of a
Diacetylene Precursor. Chem 2016, 1 (1), 78–90.
(30) Jordan, R. S.; Li, Y. L.; Lin, C.-W.; McCurdy, R. D.; Lin, J. B.;
Brosmer, J. L.; Marsh, K. L.; Khan, S. I.; Houk, K. N.; Kaner, R. B.; Rubin,
Y. Synthesis of N = 8 Armchair Graphene Nanoribbons from Four Distinct
Polydiacetylenes. J. Am. Chem. Soc. 2017, 139 (44), 15878–15890.
(31) Hein, S. J.; Lehnherr, D.; Arslan, H.; J. Uribe-Romo, F.; Dichtel, W.
R. Alkyne Benzannulation Reactions for the Synthesis of Novel Aromatic
Architectures. Acc. Chem. Res. 2017, 50 (11), 2776–2788.
(46) Gröber, S.; Görls, H.; Weigand, W. Photochemical Carbon–Car-
bon Bond Cleavage of CF3-Substituted (Dppbe)Pt0(Η2-Tolane) Com-
plexes. Eur. J. Inorg. Chem. 2015, 2015 (1), 149–155.
ACS Paragon Plus Environment

Page 9 of 9
Journal of the American Chemical Society
[TOC Graphic here]
1
2
3
4
5
6
7
8
9
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
9
ACS Paragon Plus Environment