Carbon networks based on dehydrobenzoannulenes. 5. Extension of two-dimensional conjugation in graphdiyne nanoarchitectures

Article abstract of DOI:10.1021/jo050926v

The synthesis and optical properties of a series of multinanometer-sized substructures of the phenyldiacetylene carbon allotrope, graphdiyne, are described. These molecules are among the largest and most complex annulenic systems yet prepared, with extens

Full text of DOI:10.1021/jo050926v

VOLUME 70, NUMBER 25
DECEMBER 9, 2005
© Copyright 2005 by the American Chemical Society
Carbon Networks Based on Dehydrobenzoannulenes. 5. Extension
of Two-Dimensional Conjugation in Graphdiyne
Nanoarchitectures
Jeremiah A. Marsden and Michael M. Haley*
Department of Chemistry, Materials Science Institute, and Oregon Nanosciences and
Microtechnologies Institute, University of Oregon, Eugene, Oregon 97403-1253
haley@uoregon.edu
Received May 9, 2005
The synthesis and optical properties of a series of multinanometer-sized substructures of the phenyl-
diacetylene carbon allotrope, graphdiyne, are described. These molecules are among the largest
and most complex annulenic systems yet prepared, with extension of linear conjugation in two-
dimensions to over twice that of any previously reported planar macrocycle. The graphdiyne
substructures are constructed through convergent syntheses, taking advantage of three key
intermediates and silane-protected phenylacetylenes. Intramolecular macrocyclization of R,ω-polyyne
precursors via Cu-mediated or Pd-catalyzed oxidative homocoupling affords five new graphdiyne
“oligomers” possessing two to four fused 18-membered rings. The attempted synthesis of a six-ring
analogue is also reported.
Introduction
Over the past 20 years, highly conjugated organic
materials have been recognized as ideal candidates for
use in next-generation electronic and optoelectronic
devices and media because of their unique electrical,
optical, and structural properties.1 Organic materials are
of particular attraction due to the ease of structural fine-
tuning to enhance specific properties for specialized
applications such as optical switches, thin-film transis-
tors, liquid crystals, optical storage devices, etc.2 Phenyl-
acetylenes are a key class of highly conjugated organic
materials that have seen extensive study for use in such
advanced applications owing in large part to their highly
polarizable π-electrons and structural rigidity.3
As part of our ongoing studies of phenylacetylene
preparation of increasingly larger substructures of the
systems,4 we have focused much of our efforts on the
theoretical all-carbon network graphdiyne (1).5 Graph-
10.1021/jo050926v CCC: $30.25 © 2005 American Chemical Society
Published on Web 07/27/2005
J. Org. Chem. 2005, 70, 10213-10226
10213

Marsden and Haley
diyne is predicted to exhibit fascinating properties in-
cluding high third-order nonlinear optical (NLO) suscep-
tibility, high fluorescence efficiency, extreme hardness,
thermal resistance, conductivity or superconductivity,
and through-sheet transport of ions.5,6 With a calculated
heat of formation of 18.3 kcal per gram-atom and virtu-
ally no strain energy,7 it is predicted to be the most stable
carbon allotrope containing diacetylene linkages and
therefore one of the most “synthetically approachable”.5a,8
Direct preparation of graphdiyne, however, has not yet
been successful;9 therefore, as previously reported,7,10 we
have constructed model substructures based on its sim-
plest macrocyclic unit, dodecadehydrotribenzo[18]annulene
(DBA, 2). Intrigued by early failed attempts at 2 and
other similar annulenic systems via intermolecular cy-
clooligomerization,11 which resulted mainly in insepa-
rable mixtures of dimer, trimer, and tetramer,4,9b,11d,12 we
utilized an intramolecular cyclization procedure by means
of R,ω-polyynes under pseudo high-dilution homocoupling
conditions. Using this methodology, we successfully
constructed 2 and several additional two- and three-ring
fused graphdiyne substructures.4,7,10
We have been particularly interested in the electronic
absorption properties of the graphdiyne subunits, which
provide clues to the potential for further optical proper-
ties such as NLO susceptibility and two-photon absorp-
tion.13 The remarkable optical properties of graphdiyne
“oligomers” presumably arise from the extended two-
dimensional π-conjugation present in the systems. The
extent of delocalization is apparent by bathochromic
shifts in the UV-vis absorption spectra. We found that
the largest bathochromic shifts displayed by graphdiyne
substructures belonged to the systems possessing the
longer linear p-bis(phenylbutadiynyl)benzene chromo-
phores, indicating that enhanced optical effects are more
a function of effective linear conjugation length than
macrocycle size or molecular weight.7b We have therefore
designed larger graphdiyne substructures possessing
further extension of linear conjugation in two dimensions
with hopes to increase the effective π-delocalization and
to provide further clues to the bulk properties of the
theoretical all-carbon network. The syntheses of macro-
cycles 3-6 and attempts at 7 are herein reported, as well
as a discussion of their optical absorption and emission
characteristics.
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Results and Discussion
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Retrosynthesis. The common feature present in all
previously reported bis- and tris[18]annulenes was a
central symmetrical benzene ring onto which each mac-
rocycle was fused. To prepare larger systems with fusion
in patterns other than to a central ring, the previous
methodology needed modification. To address this, asym-
metric coupling piece 8, composed of one and a half
precyclized 18-membered rings, was designed (Scheme
1). The butadiynyl terminus of this component can be
cross-coupled to a variety of haloarene units followed by
multiple intramolecular cyclizations to give the “super-
sized” graphdiyne substructures 3-7. To control place-
ment of each alkyne unit during the construction of “key
piece” 8, the 1,2,4,5-substituted asymmetric arene 9
possessing three different coupling positions was de-
signed and synthesized in four steps from a known
precursor.
Another important issue that needed addressing for
the successful construction of larger annulenic structures
was the poor solubility of the planar DBAs. During the
syntheses of prior graphdiyne subunits, solubility became
a problem with substructures possessing more than one
18-membered ring; therefore, solubilizing appendages
such as tert-butyl and n-decyl were built into the systems
(11) (a) Eglinton, G.; Galbraith, A. R. Proc. Chem. Soc. 1957, 350-
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10214 J. Org. Chem., Vol. 70, No. 25, 2005

2D Conjugation in Graphdiyne Nanoarchitectures
SCHEME 1. Synthetic Strategy for Super-Sized Substructure Targets
at the periphery of the rings via triyne units such as 10,
which are the origin of the outer annulene rings. While
the larger decyl chains provided better enhancement to
solubility than the tert-butyl groups, the solubilities of
the two- and three-ringed systems were still relatively
poor. To combat the anticipated amplification of solubility
problems associated with the larger macrocycles 3-7,
several additional groups were investigated, such as tert-
octyl, polyether, and 3,5-di-tert-butylphenyl (DTBP).14 Of
the three, the bulky, highly branched di-tert-butylphenyl
unit imparted good solubility and the greatest ease in
synthesis.
Syntheses. The preparation of triyne 10 began with
attachment of the solubilizing group as 1-bromo-3,5-di-
tert-butylbenzene (11),15 which was converted to its
respective boronic ester and subsequently cross-coupled
with 1-bromo-4-nitrobenzene (Scheme 2).16 Reduction of
the resultant nitrobiphenyl gave amine 12, followed by
iodination with BnEt3N+ ICl2- to afford 13 in 88% yield.17
Conversion of the amino group to a piperidinyltriazene
by means of diazonium chemistry provided 14 (89%).18
Sonogashira cross-coupling of 14 with triisopropylsilyl-
acetylene (TIPSA) gave 15, which was treated with MeI
at 140 °C, converting the triazene moiety the iodide in
16.18 A final cross-coupling of trimethylsilylbutadiyne
(TMSB) afforded triyne 10 in 55% overall yield for the
seven steps.
(15) Although commercially available, it is considerably less expen-
sive to prepare 11 from 1,3,5-tri-tert-butylbenzene, which is also
commercially available. See: Bartlett, P. D.; Roha, M.; Stiles, R. M. J.
Am. Chem. Soc. 1954, 76, 2349-2351.
(16) Klein, M.; Erdinger, L.; Boche, G. Mutat. Res. 2000, 467, 69-
82.
(17) Kajigaeshi, S.; Kakinami, T.; Yamasaki, H.; Fujisaki, S.;
Okamoto, T. Bull. Chem. Soc. Jpn. 1988, 61, 600-603.
(18) Moore, J. S.; Weinstein, E. J.; Wu, Z. Tetrahedron Lett. 1991,
32, 2465-2466.
(14) Marsden, J. A. Ph.D. Thesis, University of Oregon, 2005.
J. Org. Chem, Vol. 70, No. 25, 2005 10215

Marsden and Haley
SCHEME 2a
SCHEME 3a
a Reagents and conditions: (a) 1,2,4,5-tetraiodobenzene, KOH
(aq), Pd(PPh3)4, CuI, i-Pr2NH, THF, 50 °C; (b) [i] TBAF, THF, [ii]
CuCl, Cu(OAc)2, pyridine, 60 °C; (c) [i] TBAF, THF, [ii] Pd-
(dppe)Cl2, CuI, I2, i-Pr2NH, THF, 50 °C.
filtration through silica gel to which many of the larger
macrocycles are either unstable or have solubilities too
poor to be carried through in the filtrate.
a Reagents and conditions: (a) [i] t-BuLi, (i-PrO)3B, Et2O, THF,
-100 °C to room temperature, [ii] 1-bromo-4-nitrobenzene, NaOEt,
Pd(PPh3)4, PhMe, H2O, reflux; (b) Sn, HCl, EtOH, H2O, reflux; (c)
BnEt3N+ICl2-, CaCO3, CH2Cl2, MeOH; (d) [i] HCl, NaNO2,
CH3CN, THF, H2O, -10 °C, [ii] piperidine, K2CO3, CH3CN, H2O,
-10 °C to room temperature; (e) TIPSA, Pd(PPh3)4, CuI, i-Pr2NH,
THF, 40 °C; (f) MeI, 140 °C; (g) TMSB, Pd(PPh3)4, CuI, i-Pr2NH,
THF, 40 °C.
With bis[18]annulene 17 in hand we tested its solubil-
ity in CH2Cl2 at room temperature against its n-decyl
analogue. To our chagrin, we found that the 17 was
somewhat less soluble (35 vs 55 µM), although the DTBP
groups do provide other benefits such as enhancement
of the optical emission and absorption characteristics due
to increased conjugation. Most of the DTBP precursors
were also solids rather than the thick oils characteristic
of the decyl-substituted polyynes, allowing ease in han-
dling and isolation. We therefore decided to continue the
syntheses of the larger graphdiyne substructures using
the 3,5-di-tert-butylphenyl groups for solubility.
The synthesis of asymmetrically substituted arene 9,
needed for construction of key piece 8, starts from known
1,2-diiodo-4,5-dinitrobenzene (19, Scheme 4).21 Using
NH3 gas, substitution of one nitro group with an amino
gave aniline 20.21,22 The amino group was then converted
to a bromide through a diazotization affording 21,23 which
was reduced to aniline 22. Diazotization of 22 followed
by quenching with HNMe2 furnished multigram quanti-
ties of triazene 9 in 71% yield for the four steps.
To test the effectiveness of the DTBP solubilizing
group, bis[18]annulene 17 was synthesized to directly
compare its solubility with that of its previously reported
analogue functionalized with n-decyl groups.7 Triyne 10
was desilated and cross-coupled to 1,2,4,5-tetraiodoben-
zene in an excellent 83% yield (96% for each transforma-
tion) providing R,ω-polyyne 18 (Scheme 3). The TIPS
groups on precursor 18 were removed with TBAF, and
the polyyne was subjected to pseudo-high dilution Cu-
mediated cyclization conditions to give DBA 17 in 68%
yield.19 By using a Pd-catalyzed procedure for homocou-
pling under similar pseudo-high dilution, which we
recently reported for the preparation of bis[14]- and bis-
[15]annulenes,20 we were able to increase the cyclization
yield to a respectable 84%. Another benefit of the Pd-
catalyzed route is in the ease of workup and purification,
which typically involves concentration of the reaction
mixture and filtration with washes of hexanes/CH2Cl2 to
give the bright yellow DBAs that rarely needed further
purification. The major drawbacks of the Cu/pyridine
route include removal and use of pyridine as a solvent
and the large excess of Cu salts, typically requiring
The synthesis of polyyne 8 continued with the conver-
gent cross-coupling of triyne 10 and arene 9 (Scheme 5).
Because of the characteristic instability of terminal
phenylbutadiynes, especially when concentrated, depro-
tection and cross-coupling of trimethylsilylbutadiynes are
(21) Arotsky, J.; Butler, R.; Darby, A. C. J. Chem. Soc. 1970, 109,
5478-5486.
(19) Siemsen, P.; Livingston, R. C.; Diederich, F. Angew. Chem., Int.
Ed. 2000, 39, 2632-2657.
(20) (a) Marsden, J. A.; Miller, J. J.; Haley, M. M. Angew. Chem.,
Int. Ed. 2004, 43, 1694-1697. (b) Marsden, J. A.; Miller, J. J.; Shirtcliff,
L. D.; Haley, M. M. J. Am. Chem. Soc. 2005, 127, 2464-2476.
(22) Senskey, M. D.; Bradshaw, J. D.; Tessier, C. A.; Youngs, W. J.
Tetrahedron Lett. 1995, 36, 6217-6220.
(23) Doyle, M. P.; Siegfried, B.; J. F. Dellaria, J. J. Org. Chem. 1977,
42, 2426-2431.
10216 J. Org. Chem., Vol. 70, No. 25, 2005

2D Conjugation in Graphdiyne Nanoarchitectures
SCHEME 4a
SCHEME 6a
a Reagents and conditions: (a) NH3, THF; (b) t-BuONO, CuBr2,
CH3CN, 60 °C; (c) FeSO4‚7H2O, NH4OH, 80 °C; (d) [i] HCl, NaNO2,
CH3CN, THF, H2O, -10 °C, [ii] Me2NH, K2CO3, CH3CN, H2O, -10
°C to room temperature.
SCHEME 5a
a Reagents and conditions: (a) 1,2-didecyl-4,5-diiodobenzene,
KOH (aq), Pd(PPh3)4, CuI, i-Pr2NH, THF, 50 °C; (b) [i] TBAF, THF,
[ii] CuCl, Cu(OAc)2, pyridine, 60 °C; (c) [i] TBAF, THF, [ii]
Pd(dppe)Cl2, CuI, I2, i-Pr2NH, THF, 50 °C.
latter step, triazene decomposition with MeI for 24 gave
only degradation above 140 °C, whereas below this
temperature no reaction occurred. For that reason,
several modifications were attempted until we found
optimal conversion by reacting the triazene with HI and
I2 at 60 °C for 30 min.25 A final cross-coupling of 24 and
trimethylsilylbutadiyne gave key piece 8 in 34% yield
over the five steps.
Tris[18]annulene 3 was prepared by an in situ depro-
tection/alkynylation of 2 equiv of key piece 8 with 1,2-
didecyl-4,5-diiodobenzene,11d giving acyclic precursor 25
in 51% yield (Scheme 6). After deprotection of the TIPS
groups, we again performed both Cu-mediated and Pd-
catalyzed cyclizations, providing graphdiyne subunit 3
as a bright yellow solid. A reversal of yields for the
cyclization of this structure was seen (49% Cu, 21% Pd),
although both procedures gave moderate yields for an
annulenic structure of this size.
The linear conjugated pathway is further extended in
“linear” tetra[18]annulene 4 to nearly 5 nm, over twice
as long as any previously known graphdiyne subunit. The
central core of this system was constructed by deprotec-
tion/alkynylation of 2 equiv of triyne 10 to the iodo
positions of 1,4-dibromo-2,5-diiodobenzene (26),26 followed
by conversion of the remaining bromides to iodides by
BuLi and I2 in order to decrease the temperature
requirements necessary for the second cross-coupling
sequence (Scheme 7). Key piece 8 was next attached at
the iodo positions of 27 providing 28 in 57% yield.
Cyclization, after TIPS deprotection, by Cu (26%) or Pd
(9%) gave tetracycle 4 as a very insoluble yellow solid.
a Reagents and conditions: (a) K2CO3, THF, MeOH; (b) 9,
Pd(PPh3)4, CuI, i-Pr2NH, THF, 50 °C; (c) TIPSA, Pd(PPh3)4, CuI,
i-Pr2NH, THF, 80 °C; (d) HI (aq), I2, CCl4, CH3CN, 60 °C; (e)
TMSB, Pd(PPh3)4, CuI, i-Pr2NH, THF, 40 °C.
typically performed in one step; however, the in situ
protiodesilylation/alkynylation procedure24 of 9 and 10
gave a mixture of products, including elimination of the
triazene and/or halides and substitution with a proton.
Triyne 10 was therefore deprotected beforehand with
K2CO3/MeOH. The inorganic salts were filtered off, and
the solution was degassed and cross-coupled with no need
to concentrate the terminal phenylbutadiyne, providing
hexayne 23 in 75% yield with no detectable decomposi-
tion of the triazene or halides. A second cross-coupling
with TIPSA to the bromo position at elevated tempera-
ture in a sealed vessel, followed by conversion of the
triazene to an iodide, provided iodoarene 24. For the
(24) (a) Haley, M. M.; Bell, M. L.; English, J. J.; Johnson, C. A.;
Weakley, T. J. R. J. Am. Chem. Soc. 1997, 119, 2956-2957. (b) Bell,
M. L.; Chiechi, R. C.; Kimball, D. B.; Johnson, C. A.; Matzger, A. J.;
Wan, W. B.; Weakley, T. J. R.; Haley, M. M. Tetrahedron 2001, 57,
3507-3520.
(25) Barbero, M.; Degani, I.; Diulgheroff, N.; Dughera, S.; Fochi, R.
Synthesis 2001, 2180-2190.
(26) Goldfinger, M. B.; Crawford, K. B.; Swager, T. M. J. Am. Chem.
Soc. 1997, 119, 4578-4593.
J. Org. Chem, Vol. 70, No. 25, 2005 10217

Marsden and Haley
SCHEME 7a
SCHEME 8a
a Reagents and conditions: (a) 10, KOH (aq), Pd(PPh3)4, CuI,
i-Pr2NH, THF; (b) BuLi, I2, THF, -78 °C to room temperature;
(c) 8, KOH (aq), Pd(PPh3)4, CuI, i-Pr2NH, THF, 55 °C; (d) [i] TBAF,
THF, [ii] CuCl, Cu(OAc)2, pyridine, 60 °C; (e) [i] TBAF, THF, [ii]
Pd(dppe)Cl2, CuI, I2, i-Pr2NH, THF, 50 °C.
a Reagents and conditions: (a) 10, KOH (aq), Pd(PPh3)4, CuI,
i-Pr2NH, THF, 40 °C; (b) BuLi, I2, THF, -78 °C to room temper-
ature; (c) 8, KOH (aq), Pd(PPh3)4, CuI, i-Pr2NH, THF, 55 °C; (d)
[i] TBAF, THF, [ii] CuCl, Cu(OAc)2, pyridine, 60 °C; (e) [i] TBAF,
THF, [ii] Pd(dppe)Cl2, CuI, I2, i-Pr2NH, THF, 50 °C.
intermolecularly couple, forming the oligomeric material.
Although alkynes C and D are also separated by a
comparable distance, formation of the resultant 19-
membered ring would be improbable because of the high
ring strain associated with this size cycle. A much higher
yield of 32% was achieved via Pd-catalyzed cyclization,
likely attributable to the geometry about the Pd center.
Using a cis-bidentate ligand, 1,2-bis(diphenylphosphino)-
ethane (dppe), addition of the acetylides to Pd must
transpire in a cis-orientation that is unlikely between
alkynes A and B and much more facile for formation of
the desired 18-membered rings.20 Upon formation, we
found that the bent tetra[18]annulene isomer 5 was much
more soluble than isomer 4 at 8 µM in CH2Cl2 at room
temperature, likely as a result of the reduction in size
across the macrocycle and/or lower symmetry.
Solubility for this system was estimated at ca. 0.1 µM in
CH2Cl2 at room temperature, thus preventing character-
ization by NMR spectroscopy.
To compare structural isomers with different conju-
gated pathways, “bent” tetra[18]annulene 5 was prepared
through a similar series of reactions used for DBA 4
(Scheme 8). Starting from 1,5-dibromo-2,4-diiodobenzene
(29),26 triyne cross-coupling and bromide-iodide conver-
sion gave the central piece 30 (55%). A second series of
cross-couplings with 8 gave precursor 31, which was
again deprotected and cyclized by Cu or Pd procedures.
Less than 1% of tetra[18]annulene 5 was isolated after
Cu-mediated cyclization along with copious amount of
oligomeric material. The most likely explanation for this
occurrence is intramolecular coupling across alkynes A
and B, which are in close enough proximity to each other
to bridge through the bis(Cu-acetylide) intermediate,19,27
forming a 33-membered ring. In turn, this undesirable
ring formation would force the adjacent alkynes to
The “star-shaped” tetra[18]annulene 6 is also made up
of four graphdiyne subunits and possesses an interesting
D3h symmetry with three linear “hexayne” chromophores.
A modification from the syntheses of the previous DBAs
was necessary for 6 due to the likelihood of benzyne
(27) Bohlmann, F.; Scho¨nowsky, H.; Inhoffen, E.; Grau, G. Chem.
Ber. 1963, 97, 794-800.
10218 J. Org. Chem., Vol. 70, No. 25, 2005

2D Conjugation in Graphdiyne Nanoarchitectures
SCHEME 9a
SCHEME 10a
a Reagents and conditions: (a) 1,2,4,5-tetraiodobenzene, KOH
(aq), Pd(PPh3)4, CuI, i-Pr2NH, THF, 55 °C; (b) [i] TBAF, THF, [ii]
CuCl, Cu(OAc)2, pyridine, 60 °C; (c) [i] TBAF, THF, [ii] Pd-
(dppe)Cl2, CuI, I2, i-Pr2NH, THF, 50 °C.
and Cu-mediated conditions resulted in an abundant
amount of oligomeric material and ∼1% of macrocycle 6,
although providing enough material for analysis of its
electronic properties.
Multiple attempts at the construction of the largest
planned substructure, hexa[18]annulene 7, from its
precursor 35 (made by tetra-coupling of 8 with 1,2,4,5-
tetraiodobenzene) were unsuccessful (Scheme 10). De-
spite modifications to the cyclization conditions, such as
addition time, temperature, and concentration, only dark,
oligomeric material resulting from intermolecular alkyne
couplings was isolated. This result is not surprising,
because of the size of the desired DBA system and the
number of simultaneous intramolecular homocouplings
necessary for product formation.
Properties. All graphdiyne subunits prepared were
isolated as bright yellow, microcrystalline solids. As
expected, their solubilities were increasingly poor as the
overall size of the systems increased. Most notable was
the very poor solubility of macrocycle 4, with the largest
calculated end-to-end distance of greater than 5 nm. In
this macrocycle we have most likely reached the feasible
size limit for solubility that the 3,5-di-tert-butylphenyl
groups can adequately provide.
All annulenic (excluding 4 and 6) and intermediate
structures were fully characterized spectroscopically.
Consistent with our previous studies on smaller dehydro-
benzo[18]annulene graphdiyne substructures,7,10 a weak
aromatic ring current arising from the multiple [4n + 2]
π-electron circuits present in each 18-membered ring was
discernible based on comparison of the 1H NMR spectra
of the annulenes and the R,ω-polyyne intermediates. In
each case, a distinct downfield shift (∆δ ) 0.25-0.30
a Reagents and conditions: (a) 8, KOH (aq), Pd(PPh3)4, CuI,
i-Pr2NH, THF, 45 °C; (b) 10, KOH (aq), Pd(PPh3)4, CuI, i-Pr2NH,
THF, reflux; (c) [i] TBAF, THF, [ii] CuCl, Cu(OAc)2, pyridine, 60
°C; (d) [i] TBAF, THF, [ii] Pd(dppe)Cl2, CuI, I2, i-Pr2NH, THF, 50
°C.
formation in the lithiation step of the o-dibromoarene.
The less stable alkyne coupling piece 8 was first depro-
tected in situ and cross-coupled to the iodo positions of
1,2-dibromo-4,5-diiodobenzene,28 (32) providing dibromo
precursor 33 in 55% yield (Scheme 9). A second in situ
deprotection/alkynylation of triyne 10 with 33 at elevated
temperature gave the precyclized polyyne 34 (37%).
Cyclization of this compound under both Pd-catalyzed
(28) Miljanic, O. S.; Vollhardt, K. P. C.; Whitener, G. D. Synlett 2003,
29-34.
J. Org. Chem, Vol. 70, No. 25, 2005 10219

Marsden and Haley
TABLE 1. Selected Peaks from the Electronic
Absorption Spectra of Macrocycles 2-6 and 17
DBA
peak 1a
peak 2a
peak 3a
nb
2c
17
3
330 (72,000)
388 (139,000)
392 (256,000)
398 (391,000)
407
394 (301,000)
415 (264,000)
360 (21,000)
423 (76,000)
434 (180,000)
438 (311,000)
454
409 (299,000)
428 (204,000)
380 (24,000)
439 (65,000)
454 (130,000)
462 (263,000)
485
447 (242,000)
448 (295,000)
1
2
3
4
4
d
∞
5
6
3
3
a Peak values are in nm with molar absorptivity (M-1 cm-1).
b n ) the number of phenylbutadiyne units in the longest linear
conjugated pathway. c Reference 7. d Calculated from Figure 3.
FIGURE 1. Electronic absorption spectra of precursor 18,
macrocycle 17, and the n-decyl analogue of 17.
ppm) of the interannulenic aromatic protons of the DBAs
from their respective precursors was observed, indicating
the presence of weak diatropic ring currents.
Of the predicted materials properties of the network
graphdiyne and its subunits, the optical absorption and
emission as well as NLO properties are the most readily
observable and arguably of greatest interest for elec-
trooptical devices. Each graphdiyne subunit shows a
characteristic pattern of three major low-energy peaks
from which much information can be gathered from the
position and intensity of these absorption bands (Figures
1-4). The interesting electronic properties presumably
arise from the extended two-dimensional conjugation
present in the planar DBAs. The extent of delocalization
can be readily observed by bathochromic shifts in the low-
energy peaks of the UV-vis spectra of each system.
These low-energy peaks are generally attributed to π f
π* transitions of the HOMO to the LUMO and the
associated energy is minimized by increasing delocaliza-
tion. Delocalization is greatly increased upon cyclization
resulting from the introduction of new chromophores in
the rings, ring currents, and planarization of the entire
phenylacetylene framework, which can be seen in Figures
1 and 3, where bathochromic shifts of 10-25 nm from
acyclic precursor to annulene were observed. The fine
vibronic structure present in the macrocyclic systems and
absent in the acyclic intermediates is easily visible,
appearing as multiple, tight absorption peaks rather than
the broad absorption bands present in the precycles. The
added conjugation from the DTBP solubilizing groups
over the previously used n-decyl chains also provided an
additional red-shift of ∼10 nm for each of the three main
absorption bands in 17 compared to its previously
reported decyl analogue (Figure 1).7
FIGURE 2. Electronic absorption spectra of graphdiyne
substructures 2-4 and 17.
chromophores present.30 This trend continues with mac-
rocycles 17, 3, and 4. As each additional ring is fused
onto the system in a zigzag pattern, the linearly conju-
gated pathway is extended by one phenylbutadiyne unit.
With increasing linear conjugation, the low-energy ab-
sorption peaks (peaks 1-3, Table 1) undergo a dramatic
rise in molar absorptivity (ꢀ) and further bathochromic
shift (Figure 2). The magnitude of these bathochromic
shifts, however, decreases with each successively fused
phenylbutadiyne unit (n), indicating saturation (∆λmax
/
∆n ) 0) of the longest-wavelength λmax is occurring.
Similar saturations have been observed for linear
polyynes.31 The saturation wavelength can be calculated
by plotting 1/n vs the longest-wavelength λmax, which
gives a linear fit for DBAs 3, 4, and 17 (n ) 2-4, Figure
3). Extrapolating for n ) ∞ predicts a saturation point of
485 nm (2.56 eV) for λmax, which represents the HOMO-
LUMO energy gap of an infinite zigzag pattern of
graphdiyne subunits fused in a linear fashion such as in
substructures 17, 3, and 4. A much lower value of only
0.53 eV has been calculated for the band-gap energy of
the entire graphdiyne network by Narita et al.12 Subunit
4, possessing the longest linear conjugated pathway of
As we7,10,20 and others3,13a,29 have shown, bathochromic
shifts in neutral- and donor-substituted phenylacetylene
systems are maximized by linear conjugation, taking
advantage of both length and the number of linear
(30) Meier, H.; Mu¨hling, B.; Kolshorn, H. Eur. J. Org. Chem. 2004,
1033-1042.
(31) Inter alia: (a) Johnson, T. R.; Walton, D. R. M. Tetrahedron
1972, 28, 5221-5230. (b) Dembinski, R.; Bartik, T.; Bartik, B.; Jaeger,
M.; Gladysz, J. A. J. Am. Chem. Soc. 2000, 122, 810-818. (c) Gibtner,
T.; Hampel, F.; Gisselbrecht, J. P.; Hirsch, A. Chem. Eur. J. 2002, 8,
408-432. (d) Luu, T.; Elliott, E.; Slepkov, A. D.; Eisler, S; McDonald,
R.; Hegmann, F. A.; Tykwinski, R. R. Org. Lett. 2005, 7, 51-54. (e)
Eisler, S.; Slepkov, A. D.; Elliott, E.; Luu, T.; McDonald, R.; Hegmann,
F. A.; Tykwinski, R. R. J. Am. Chem. Soc. 2005, 127, 2666-2676.
(29) (a) Tykwinski, R. R.; Schreiber, M.; Carlo´n, R. P.; Diederich,
F.; Gramlich, V. Helv. Chim. Acta 1996, 79, 2249-2280. (b) Tykwinski,
R. R.; Schreiber, M.; Gramlich, V.; Seiler, P.; Diederich, F. Adv. Mater.
1996, 8, 226-31. (c) Wilson, J. N.; Smith, M. D.; Enkelmann, V.; Bunz,
U. H. F. Chem. Commun. 2004, 1700-1701. (d) Wilson, J. N.; Josowicz,
M.; Wang, Y.; Bunz, U. H. F. Chem. Commun. 2003, 2962-2963.
10220 J. Org. Chem., Vol. 70, No. 25, 2005

2D Conjugation in Graphdiyne Nanoarchitectures
tronic absorption wavelength and molar absorptivity,
UV-vis spectra of tris[18]annulene 3 and tetra[18]-
annulene isomers 4-6 were compared. Structures 3, 5,
and 6 all possess a longest, linear-conjugated pathway
of n ) 3 and show little variance in the wavelength of
the lowest-energy λmax of 454, 447, and 448 nm, respec-
tively (Figure 4, Table 1); however, a striking difference
is observed in their molar absorptivities, which increase
dramatically with the number of n ) 3 pathways present
in the macrocycle (one in 3, two in 5, and three in 6).
Tetra[18]annulene 4, with no n ) 3 linear conjugated
pathway but one n ) 4 pathway, displays a red-shift of
the lowest-energy λmax from 3, 5, and 6 of ∼15 nm and a
value of ꢀ between that of 5 and 6. These data indicate
that the wavelength, or HOMO-LUMO band-gap energy,
is dictated more by the length of the longest linear
conjugated pathway, whereas the molar absorptivity is
dictated more by the number of long pathways present.
FIGURE 3. Plot of λmax versus 1/n for the low-energy peaks
of DBAs 3, 4, and 17, where n ) the number of phenyl-
butadiyne units in the longest linear conjugated pathway.
Each macrocycle and its acyclic precursor are also quite
fluorescent, and their solution-based emission was mea-
sured in CH2Cl2 and PhMe (Figure 5 and Table 2). The
increased conjugation due to planarization and cycliza-
tion generally resulted in an increase of 2-3 times the
quantum efficiency to 30-60% and a slight bathochromic
shift of the emission λmax. Solvent polarity showed little
effect on quantum yield between CH2Cl2 and PhMe,
although a variance in peak structure was observed. For
the most part, only one broad emission band was seen
in CH2Cl2, while fine structure was more pronounced for
the larger macrocycles in PhMe with at least three
individual peaks observable for tetra[18]annulenes 4-6.
As with the absorption spectra, increasing the number
of long linear chromophores had a pronounced effect on
the emission spectra of the graphdiyne substructures.
With macrocycles 3, 5, and 6, as the number of n ) 3
pathways increased, a quantum efficiency increase of
∼10% and a bathochromic shift of ∼5 nm resulted from
each additional pathway. Comparatively, DBA 4, con-
taining a longer n ) 4 conjugated pathway, showed an
emission spectrum only slightly hypsochromically shifted
from that of 6. These data indicate that for emission
properties in the graphdiyne substructures, three n ) 3
pathways behave similarly to one n ) 4.
FIGURE 4. Electronic absorption spectra of graphdiyne
substructures 3-6 and their acyclic precursors.
any reported annulenic structure, is only 24 nm (0.13 eV)
from the predicted saturation value, suggesting that
further extension of the pathway would provide little
enhancement to the optical properties. The saturation
wavelengths of absorption peaks 1 and 2 were similarly
calculated and are reported in Table 1.
To gain further insight into the influence of the number
and length of linear conjugated pathways on the elec-
Macrocycles 3-6 and 17 proved to be air-stable over a
period of several months and much more robust to
FIGURE 5. Optical emission spectra of graphdiyne substructures 3-6 and 17 in CH2Cl2 (left) and PhMe (right). The y-axis scale
has been normalized.
J. Org. Chem, Vol. 70, No. 25, 2005 10221

Marsden and Haley
TABLE 2. Optical Emission Data for Macrocycles 3-6
Coupling constants are expressed in hertz. Melting points were
recorded on a melting point apparatus in open-end capillary
tubes or on a DSC in air and are uncorrected. IR spectra were
recorded using an FTIR spectrometer. UV-vis spectra were
recorded on a UV-vis spectrophotometer. Mass spectra were
recorded on an LC/MSD spectrometer. THF and Et2O were
purified by a solvent purification system. All other chemicals
were of reagent quality and used as obtained from manufac-
turers. Column flash chromatography was performed using N2
or air pressure on silica gel (230-450 mesh). Precoated silica
gel plates (200 × 200 × 0.50 mm) were used for analytical
thin-layer chromatography. Eluting solvents were reagent
quality and used as obtained from the manufacturers. Reac-
tions were carried out in an inert atmosphere (dry Ar) when
necessary. All deprotected terminal alkynes were used directly
without further purification.
General Alkyne Cross-Coupling Procedure A. Halo-
arene (1 equiv) and terminal alkyne, if solid or viscous oil
(addition of liquid alkynes occurred via injection after Ar
purge) (1.1 equiv per transformation), were dissolved in i-Pr2-
NH/THF (1:1, ∼0.1 M) in a round-bottom flask. The solution
was purged for 30 min with bubbling Ar followed by addition
of Pd(PPh3)4 (0.03 equiv per transformation) and CuI (0.06
equiv per transformation). The reaction mixture then stirred
at room temperature to 80 °C for 2-12 h under an Ar
atmosphere. Upon completion, the mixture was concentrated,
rediluted with CH2Cl2, and filtered through a plug of silica
gel. The solvent was removed in vacuo and the crude material
was purified by column chromatography.
General in Situ Deprotection/Alkynylation Procedure
B. Haloarene (1 equiv) was dissolved in iPr2NH/THF (1:1,
∼0.01 M) in a round-bottom flask. To this solution was added
KOH (10 equiv per alkyne) dissolved in a minimal amount of
H2O. The mixture was purged for 30 min with bubbling Ar
followed by addition of Pd(PPh3)4 (0.03 equiv per transforma-
tion) and CuI (0.06 equiv per transformation). A solution of
alkyne (1.1 equiv per transformation) in THF (0.05 M) was
similarly purged with Ar and added to the haloarene solution
via syringe over 8-24 h. The reaction mixture then stirred at
room temperature to 60 °C for 2-12 h under an Ar atmo-
sphere. Upon completion, the mixture was concentrated,
rediluted with CH2Cl2, and filtered through a plug of silica
gel. The solvent was removed in vacuo and the crude material
was purified by column chromatography.
General Cu-Mediated Cyclization Procedure C. To a
solution of triisopropylsilyl-protected alkyne (1 equiv) in THF
(∼0.2 M) was added TBAF (1 M in THF, 5 equiv per silyl
group). The reaction mixture stirred at room temperature for
15 min. Upon completion, the mixture was diluted with Et2O,
washed with brine (4×) and H2O, dried (MgSO4), and concen-
trated in vacuo. The resultant terminal alkyne was then
redissolved in pyridine (50 mL) and added via syringe pump
over 24 h to a suspension of Cu(OAc2) (20 equiv) and CuCl
(25 equiv) in pyridine/MeOH (7:1, ∼3 L per mmol alkyne) at
60 °C open to air. Upon completion of the slow addition, the
reaction mixture stirred an additional 2 h. The suspension was
concentrated in vacuo, resuspended in CH2Cl2, and filtered
through a plug of silica gel. The crude annulene was then
purified by either chromatography on a plug of silica gel or by
trituration in hexanes/CH2Cl2 and filtration.
and 17 and Their Acyclic Prec
ursors
a
b
compound
solvent
λem
Stokes shifta
ΦF
18
CH2Cl2
PhMe
CH2Cl2
PhMe
CH2Cl2
PhMe
CH2Cl2
PhMe
CH2Cl2
PhMe
CH2Cl2
PhMe
CH2Cl2
PhMe
CH2Cl2
PhMe
508
79
85
67
65
86
94
53
57
65
67
58
57
67
66
66
67
70
67
72
70
67
67
0.13
0.11
0.25
0.25
0.08
0.09
0.31
0.32
0.17
0.17
0.40
0.30
0.20
0.17
0.61
0.42
0.21
0.19
0.52
0.49
0.22
0.22
507
17
25
3
508
504
510
512
512
510
28
4
509
507
518
518, 504
509
31
5
506
514
514, 502
510
507
519
519, 504
510
510
34
6
CH2Cl2
PhMe
CH2Cl2
PhMe
CH2Cl2
PhMe
35
a Values are in nm. b With reference to fluorescein.
temperature than their acyclic precursors. Decomposition
to a black, insoluble material occurred at relatively high
temperatures of 200-250 °C, resulting in a broad exo-
therm as measured by DSC, indicative of random polym-
erization/degradation, whereas most acyclic precursors
showed similar decomposition around 150-170 °C.
Conclusions
We have demonstrated the synthesis of increasingly
larger substructures (3-6) of the network graphdiyne (2)
through the use of convergent syntheses taking advan-
tage of three key pieces, nonayne 8, arene 9, and triyne
10, in conjunction with several modifications to the
Sonogashira cross-coupling protocol and intramolecular
homocoupling via Cu or Pd to affect ring closure. Incor-
poration of 3,5-di-tert-butylphenyl groups to the periphery
of the macrocycles provided both increased solubility and
enhancement of the optical properties. Electronic absorp-
tion spectra indicate a reliance of the longest-wavelength
absorption on the length of linear conjugation and
saturation of this peak shifting has nearly been reached
with macrocycle 4. A relationship was also established
between the number of long linear conjugated pathways
and an increase in molar absorptivity with values ap-
proaching 400,000 M-1 cm-1, more than double any
previously measured value for dehydrobenzoannulene
systems. Similar dependencies on chromophore length
and number were observed in the optical emission spectra
of 3-6. Currently under investigation are the origins of
the excitation properties of all graphdiyne substructures,
which will be reported in due course.
General Pd-Catalyzed Cyclization Procedure D. To a
solution of triisopropylsilyl-protected alkyne (1 equiv) in THF
(∼0.2 M) was added TBAF (1 M in THF, 5 equiv per silyl
group). The reaction mixture stirred at room temperature for
15 min. Upon completion, the solution was diluted with Et2O,
washed with brine (4×) and H2O, dried (MgSO4), and concen-
trated in vacuo. The resultant terminal alkyne was then
redissolved in THF (50 mL) and added via syringe pump over
24 h to a solution of Pd(dppe)Cl2 (0.1 equiv), CuI (0.15 equiv)
and I2 (0.5 equiv) in THF/iPr2NH (1:1, ∼2 L per mmol alkyne)
at 50 °C open to air. Upon completion of the slow addition,
the reaction mixture stirred an additional 2 h. The solution
Experimental Section
General Methods. 1H and 13C NMR spectra were recorded
in CDCl3 or CD2Cl2 using a 300 (1H, 299.94 MHz; 13C, 75.43
MHz) or 500 (1H, 500 MHz; 13C, 125 MHz) MHz spectrometer.
Chemical shifts (δ) are expressed in ppm relative to the
residual CHCl3 (1H, 7.26 ppm; 13C, 77.0 ppm) reference.
10222 J. Org. Chem., Vol. 70, No. 25, 2005

2D Conjugation in Graphdiyne Nanoarchitectures
was concentrated in vacuo, redissolved in CH2Cl2, and filtered
through a plug of silica gel. The crude annulene was then
purified by either chromatography on a plug of silica gel or by
trituration in hexanes/CH2Cl2 and filtration.
7.44 (d, J ) 1.5 Hz, 8H), 1.40 (s, 72H); 13C NMR (75 MHz,
CDCl3, 50 °C) δ 151.7, 143.5, 138.6, 136.6, 133.2, 131.5, 128.0,
126.0, 125.4, 123.4, 122.6, 121.5, 82.8, 81.3, 81.1, 79.8, 78.5,
78.3, 35.1, 31.5; IR (KBr) ν 2964, 2715, 2456, 2195, 2192, 669
cm-1; MS (APCI) m/z (%) 1491.7 (M+ + THF, 80), 1443.1 (M+
+ Na, 100), 1009.7 (60), 677.2 (60); UV (CH2Cl2) λmax (log ꢀ)
231 (5.03), 314 (4.88), 365 (4.99), 389 (5.14), 423 (4.88), 439
(4.81).
Ethynyltriazene 15. Iodoarene 14 (13.6 g, 26.3 mmol) was
reacted with TIPSA (5.29 g, 29.0 mmol) at 40 °C using general
alkyne cross-coupling procedure A (8 h). The crude material
was purified on a plug of silica gel (1:1 CH2Cl2/hexanes) to give
15 (14.9 g, 99%) as an amorphous, yellow solid: mp 84-86
°C; 1H NMR (300 MHz, CDCl3) δ 7.69 (d, J ) 1.8 Hz, 1H),
7.53 (d, J ) 8.4 Hz, 1H), 7.47 (dd, J ) 8.4, 1.8 Hz, 1H), 7.43 (t,
J ) 1.8 Hz, 1H), 7.41 (d, J ) 1.8 Hz, 2H), 3.86 (br s, 4H), 1.72
(br s, 6H), 1.39 (s, 18H), 1.16 (s, 21H); 13C NMR (75 MHz,
CDCl3) δ 151.2, 151.1, 139.8, 139.2, 132.4, 128.2, 121.41,
121.38, 118.8, 117.0, 105.3, 94.3, 35.0, 31.5, 24.4, 22.3, 18.7,
14.3, 11.4; IR (KBr) ν 3421, 2942, 2863, 2151, 1425, 1362, 1191,
1102, 678 cm-1; MS (APCI) m/z (%) 558.4 (M + H+, 100), 517.3
(10), 473.4 (40).
Ethynylbiphenyl 16. Triazene 15 (15.0 g, 26.2 mmol) in
MeI (125 mL) was heated at 140 °C in a sealed pressure vessel
for 12 h. Upon completion, the mixture was cooled to room
temperature and concentrated in vacuo. The residue was
redissolved in CH2Cl2, filtered through a plug of silica gel, and
concentrated in vacuo. The crude material was purified on a
plug of silica gel (3:1 hexanes/CH2Cl2) to give 16 (15.3 g, 99%)
as a thick, yellow oil: 1H NMR (300 MHz, CDCl3) δ 7.89 (d, J
) 8.4 Hz, 1H), 7.66 (d, J ) 1.8 Hz, 1H), 7.47 (t, J ) 1.8 Hz,
1H), 7.35 (d, J ) 1.8 Hz, 2H), 7.20 (dd, J ) 8.4, 1.8 Hz, 1H),
1.39 (s, 18H), 1.19 (s, 21H); 13C NMR (75 MHz, CDCl3) δ 151.4,
142.4, 139.0, 138.9, 132.1, 130.3, 128.7, 122.0, 121.4, 108.1,
99.1, 95.3, 35.0, 31.5, 18.7, 11.3; IR (KBr) ν 2961, 2865, 2156,
1730, 1363, 678 cm-1; MS (APCI) m/z (%) 595.3 (M+ + Na,
20), 525.3 (20), 509.3 (70), 477.3 (95), 312.8 (100).
Hexayne 23. To a solution of triyne 10 (7.00 g, 12.0 mmol)
in THF (50 mL) and MeOH (10 mL) was added K2CO3 (5.00 g,
36.0 mmol). After stirring at room temperature for 2 h, the
mixture was filtered. The resultant terminal alkyne solution
was purged with Ar for 20 min and added via syringe over 6
h to an Ar-purged solution of haloarene 9 (2.61 g, 5.44 mmol),
Pd(PPh3)4 (250 mg, 0.27 mmol), and CuI (100 mg, 0.54 mmol)
in THF (100 mL) and iPr2NH (100 mL) at 50 °C under an Ar
atmosphere. The mixture was stirred at 50 °C for an additional
9 h to completion, cooled to room temperature, diluted with
CH2Cl2 (200 mL) and washed with 10% aqueous HCl until
slightly acidic. The organic phase was dried (MgSO4), filtered
through a plug of silica gel, and concentrated in vacuo. The
crude material was purified by column chromatography (10:
1-5:1 hexanes/CH2Cl2) to give 23 (4.16 g, 75%) as a yellow
1
solid: mp 135-137 °C; H NMR (300 MHz, CDCl3) δ 7.78 (s,
1H), 7.71 (d, J ) 1.4 Hz, 2H), 7.66 (s, 1H), 7.64 (d, J ) 8.4 Hz,
1H), 7.63 (d, J ) 8.4 Hz, 1H), 7.52 (dd, J ) 8.4, 1.4 Hz, 2H),
7.49 (t, J ) 1.5 Hz, 2H), 7.41 (d, J ) 1.5 Hz, 4H), 3.62 (s, 3H),
3.33 (s, 3H), 1.41 (s, 36H), 1.23 (s, 21H), 1.22 (s, 21H); 13C NMR
(75 MHz, CDCl3) δ 151.4 (2C), 148.3, 143.1, 143.0, 139.0 (2C),
137.7, 133.1, 133.0, 131.0 (2C), 127.6, 127.5, 127.1 (2C), 124.7,
123.3 (2C), 122.5, 122.2 (2C), 121.9, 121.5 (2C), 120.3, 104.7
(2C), 96.2, 96.1, 82.4, 82.0, 80.3, 79.8, 78.9, 78.4 (2C), 78.3,
43.4, 36.5, 35.0 (2C), 31.5 (2C), 18.7 (2C), 11.4 (2C); IR (KBr)
ν 3066, 2959, 2863, 2209, 2154, 1593, 1469, 1339, 1091, 876,
832, 669 cm-1; MS (APCI) m/z (%) 1214.6 (M+(81Br) + H+, 100),
1212.6 (M+(79Br) + H+, 95), 1171.6 (15), 722.2 (95), 720.2 (50),
675.3 (15), 157.4 (20).
Triyne 10. Iodoarene 16 (5.87 g, 10.0 mmol) was reacted
with trimethylsilyl-1,3-butadiyne (2.30 g, 18.8 mmol) at 40 °C
using general alkyne cross-coupling procedure A (12 h). The
crude material was purified by column chromatography (50:1
hexanes/CH2Cl2) to give 10 (4.82 g, 83%) as an amorphous,
yellow solid: mp 70-72 °C; 1H NMR (300 MHz, CDCl3) δ 7.65
(d, J ) 1.8 Hz, 1H), 7.54 (d, J ) 8.4 Hz, 1H), 7.47 (t, J ) 1.8
Hz, 1H), 7.46 (dd, J ) 8.4, 1.8 Hz, 1H), 7.37 (d, J ) 1.8 Hz,
2H), 1.38 (s, 18H), 1.19 (s, 21H), 0.25 (s, 9H); 13C NMR (75
MHz, CDCl3) δ 151.4, 143.1, 139.0, 133.0, 131.0, 127.8, 127.2,
122.9, 122.2, 121.5, 104.6, 96.0, 91.5, 88.2, 78.3, 75.4, 35.0, 31.5,
18.7, 11.3, -0.4; IR (KBr) ν 3420, 2962, 2865, 2197, 2156, 2104,
Heptayne Triazene. Hexayne 23 (4.16 g, 3.35 mmol) was
reacted with TIPSA (1.08 g, 6.00 mmol) at 80 °C in a sealed
pressure vessel using general alkyne cross-coupling procedure
A (16 h). The crude material was purified by column chroma-
tography (10:1-7:1 hexanes/CH2Cl2) to give the product (3.45
g, 77%) as a yellow solid: mp 136-140 °C; 1H NMR (300 MHz,
CDCl3) δ 7.71-7.68 (m, 4H), 7.78 (s, 1H), 7.63 (d, J ) 8.4 Hz,
2H), 7.52 (dd, J ) 8.4, 1.4 Hz, 2H), 7.50 (t, J ) 1.5 Hz, 2H),
7.41 (d, J ) 1.5 Hz, 4H), 3.60 (s, 3H), 3.30 (s, 3H), 1.41 (s,
36H), 1.23 (s, 21H), 1.22 (s, 21H), 1.18 (21H); 13C NMR (75
MHz, CDCl3) δ 151.7, 151.4 (2C), 143.1, 143.0, 139.1, 139.0
(2C), 133.1, 133.0, 131.0 (2C), 127.6, 127.5, 127.1 (2C), 125.0,
123.5, 123.3, 122.3, 122.2, 121.7, 121.5 (2C), 120.8, 119.5,
104.7, (2C), 103.7, 97.7, 96.2, 96.1, 82.3, 81.9, 80.9, 80.5, 78.9,
78.6, 78.4, 78.3, 43.4, 36.5, 35.0 (2C), 31.0 (2C), 18.7 (3C), 11.4
1250, 1143, 1100, 846 cm-1; MS (APCI) m/z (%) 639.4 (M+
+
THF, 100), 598.4 (M+ + Na, 15), 567.2 (M + H+, 15), 531.5
(20), 392.2 (30).
Dodecayne 18. Triyne 10 (871 mg, 1.50 mmol) was reacted
with 1,2,4,5-tetraiodobenzene (194 mg, 0.333 mmol) at 50 °C
using general in situ deprotection/alkynylation procedure B
(10 h injection, 8 h additional heating). The crude material
was purified by column chromatography (20:1-7:1 hexanes/
CH2Cl2) to give 18 (578 mg, 83%) as a yellow solid: mp 150-
153 °C; 1H NMR (300 MHz, CDCl3) δ 7.72 (d, J ) 1.5 Hz, 4H),
7.68 (s, 2H), 7.67 (d, J ) 8.3 Hz, 4H), 7.53 (dd, J ) 8.3, 1.5
Hz, 4H), 7.50 (t, J ) 1.5 Hz, 4H), 7.42 (d, J ) 1.5 Hz, 8H),
1.41 (s, 72H), 1.23 (s, 84H); 13C NMR (75 MHz, CDCl3) δ 151.4,
143.4, 139.0, 137.6, 133.3, 131.1, 127.6, 127.2, 125.5, 122.9,
122.3, 121.5, 104.5, 96.4, 83.6, 81.2, 79.1, 78.0, 35.0, 31.5, 18.7,
11.3; IR (KBr) ν 2960, 2864, 2208, 2156, 1457, 668 cm-1; MS
(APCI) m/z (%) 2219.1 (M+ + THF, 40), 1908.6 (100), 1177.8
(50), 467.4 (20); UV (CH2Cl2) λmax (log ꢀ) 265 (5.20), 365 (5.06),
408 (4.95).
Bis[18]annulene 17. Polyyne 18 (143 mg, 0.068 mmol) was
subjected to general Cu-mediated cyclization procedure C or
Pd-catalyzed cyclization procedure D. The crude material was
triturated with hexanes (20 mL) and filtered to give 17 (68
mg, 64% (procedure C); 84 mg, 84% (procedure D)) as a bright
yellow solid: mp 200-220 °C (dec); 1H NMR (300 MHz, CDCl3)
δ 7.95 (s, 2H), 7.93 (d, J ) 1.8 Hz, 4H), 7.79 (d, J ) 8.1 Hz,
4H), 7.68 (dd, J ) 8.1, 1.8 Hz, 4H), 7.50 (t, J ) 1.5 Hz, 4H),
(2C), 11.3; IR (KBr) ν 2958, 2864, 2208, 2151, 1591, 1473 cm-1
;
MS (APCI) m/z (%) 1314.8 (M + H+, 20), 1002.5 (15), 822.4
(100), 722.2 (15).
Iodoheptayne 24. A solution of the heptayne triazene from
above (3.40 g, 2.53 mmol) in CCl4 (100 mL) was added to a
solution of HI (48% aqueous, 2.20 mL, 12.5 mmol) and I2 (3.18
g, 12.5 mmol) in CH3CN (100 mL) at 60 °C via syringe over
30 min. The mixture was heated an additional 15 min to
completion by TLC. After coolin to room temperature, the
mixture was diluted with CH2Cl2 (100 mL) and washed
successively with saturated NaHCO3 solution (150 mL), 5%
aqueous NaHSO3 solution (150 mL), and H2O (150 mL). The
organic phase was dried (MgSO4), filtered through a plug of
silica gel, and concentrated in vacuo. The crude material was
purified by column chromatography (50:1 hexanes/CH2Cl2) to
1
give 24 (2.60 g, 82%) as a red solid: mp 129.0-131.1 °C; H
NMR (300 MHz, CDCl3) δ 8.00 (s, 1H), 7.68-7.66 (m, 2H), 7.61
(d, J ) 8.4 Hz, 1H), 7.60 (d, J ) 8.4 Hz, 1H), 7.59 (s, 1H), 7.50
(dd, J ) 8.4, 1.4 Hz, 1H), 7.49 (dd, J ) 8.4, 1.4 Hz, 1H), 7.47
(t, J ) 1.5 Hz, 2H), 7.38 (d, J ) 1.5 Hz, 4H), 1.38 (s, 36H),
J. Org. Chem, Vol. 70, No. 25, 2005 10223

Marsden and Haley
1.18 (s, 42H), 1.17 (21H); 13C NMR (75 MHz, CDCl3) δ 151.4
(2C), 143.4, 143.3, 143.0, 139.0 (2C), 137.1, 133.2, 133.0, 131.1
(2C), 130.6, 127.7, 127.6, 127.2 (2C), 125.4, 124.9, 123.0, 122.9,
122.3 (2C), 121.5 (2C), 106.8, 104.6, 104.5, 100.3, 99.3, 96.4,
96.3, 83.6, 82.8, 80.9, 79.9, 79.1, 78.7, 78.0, 77.9, 35.0 (2C),
31.5 (2C), 18.7 (2C), 18.7, 11.3 (2C), 11.2; IR (KBr) ν 2959,
2864, 2213, 2146, 1593, 1465 cm-1; MS (APCI) m/z (%) 1442.7
(M+ + THF, 30), 1369.8 (M + H+, 100), 1277.8 (25), 1244.8
(20), 1031.2 (10), 225.3 (50).
31.9, 31.5 (2C), 30.3, 29.8, 29.7, 29.6, 29.5, 29.4, 22.7, 14.1; IR
(KBr) ν 2952, 2923, 2195, 2133, 1591, 1478, 826 cm-1; MS
(APCI) m/z (%) 2067.5 (M+ + THF, 40), 1994.7 (M + H+, 20),
1935.8 (40), 1617.2 (80), 1507.5 (100); UV (CH2Cl2) λmax (log ꢀ)
232 (5.24), 324 (5.08), 393 (5.39), 434 (5.24), 453 (5.09).
p-Dibromohexayne. Triyne 10 (612 mg, 1.08 mmol) was
reacted with 1,4-dibromo-2,5-diiodobenzene26 (239 mg, 0.490
mmol) at 40 °C using general in situ deprotection/alkynylation
procedure B (8 h injection, 8 h additional heating). The crude
material was purified by column chromatography (20:1-10:1
hexanes/CH2Cl2) to give the dibromoarene (542 mg, 90%) as a
Key Piece 8. Iodoarene 24 (2.50 g, 1.79 mmol) was reacted
with trimethylsilyl-1,3-butadiyne (328 mg, 2.68 mmol) at 35
°C using general alkyne cross-coupling procedure A (2 h). The
crude material was purified by column chromatography (33:
1-20:1 hexanes/CH2Cl2) to give 8 (1.81 g, 73%) as a brown
1
yellow solid: mp 221-226 °C; H NMR (300 MHz, CDCl3) δ
7.73 (s, 2H), 7.68 (d, J ) 1.5 Hz, 2H), 7.61 (d, J ) 8.3 Hz, 2H),
7.51 (dd, J ) 8.3, 1.5 Hz, 2H), 7.48 (t, J ) 1.5 Hz, 2H), 7.38 (d,
J ) 1.5 Hz, 4H), 1.39 (s, 36H), 1.20 (s, 42H); 13C NMR (75
MHz, CDCl3); δ 151.4, 143.6, 138.9, 137.2, 133.2, 131.1, 127.6,
127.3, 126.2, 124.1, 122.6, 122.4, 121.5, 104.5, 96.5, 84.1, 81.9,
78.9, 77.3, 35.0, 31.5, 18.7, 11.3; IR (KBr) ν 2961, 2864, 2210,
2156, 1593, 1467, 1248, 875, 668 cm-1; MS (APCI) m/z (%)
1293.5 (M+ + THF, 100), 1222.5 (M + H+, 40), 1147.2 (20),
1018.3 (20), 735.5 (40), 447.3 (60).
1
solid: mp 141-145 °C; H NMR (300 MHz, CDCl3) δ 7.68 (d,
J ) 1.8 Hz, 2H), 7.62 (s, 1H), 7.61 (d, J ) 8.4 Hz, 1H), 7.60 (d,
J ) 8.4 Hz, 1H), 7.57 (s, 1H), 7.49 (dd, J ) 8.4, 1.8 Hz, 2H),
7.47 (t, J ) 1.5 Hz, 2H), 7.38 (d, J ) 1.5 Hz, 4H), 1.39 (s, 36H),
1.19 (s, 42H), 1.18 (21H), 0.25 (s, 9H); 13C NMR (75 MHz,
CDCl3) δ 151.4 (2C), 143.4, 143.3, 142.4, 139.0 (2C), 137.1,
137.0, 133.2, 133.1, 131.0 (2C), 127.7, 127.66, 127.6, 127.2 (2C),
125.3, 124.7, 124.5, 122.9, 122.3 (2C), 121.5 (2C), 104.5(2C),
103.1, 99.8 (2C), 96.4, 93.5, 87.6, 83.5, 83.3, 81.1, 80.5 (2C),
79.4, 79.1, 77.9, 76.6, 73.7, 35.0 (2C), 31.5 (2C), 18.7 (2C), 18.6,
11.3 (2C), 11.2, -0.5; IR (KBr) ν 2960, 2865, 2208, 2156, 2099,
p-Diiodohexayne 27. A solution of dibromoarene from
above (400 mg, 0.320 mmol) in dry THF (30 mL) in a flame-
dried flask was cooled to -78 °C under an Ar atmosphere. BuLi
(2.5 M in hexane, 0.40 mL, 1.00 mmol) was added and the
solution was warmed to -40 °C over 10 min after which I2
(254 mg, 1.00 mmol) was added. The solution was brought to
room temperature, stirred for 15 min, and then quenched with
5% NaHSO3 (10 mL). The mixture was diluted with Et2O (30
mL) and washed with 5% NaHSO3 (2 × 30 mL) and H2O (30
mL). The organic phase was dried (MgSO4) and concentrated
in vacuo. The crude material was purified by column chroma-
tography (20:1 hexanes/CH2Cl2) to give 27 (282 mg, 66%) as a
1591, 1458, 847, 668 cm-1; MS (APCI) m/z (%) 1436.8 (M+
+
THF, 30), 1363.7 (M + H+, 100), 1323.7 (10), 1244.8 (10), 767.4
(10), 326.3 (20).
Tri[18]annulene Precursor 25. Key piece 8 (300 mg,
0.215 mmol) was reacted with 1,2-didecyl-4,5-diiodobenzene11d
(60 mg, 0.098 mmol) at 50 °C using general in situ deprotec-
tion/ alkynylation procedure B (8 h injection, 4 h additional
heating). The crude material was purified by column chroma-
tography (15:1 hexanes/CH2Cl2) to give 25 (149 mg, 51%) as a
yellow-brown solid: mp 116-119 °C; 1H NMR (300 MHz,
CDCl3) δ 7.66 (d, J ) 1.5 Hz, 4H), 7.64 (s, 2H), 7.63 (s, 2H),
7.60 (d, J ) 8.4 Hz, 2H), 7.59 (d, J ) 8.4 Hz, 2H), 7.48 (dd, J
) 8.4, 1.5 Hz, 4H), 7.45 (t, J ) 1.5 Hz, 4H), 7.37 (d, J ) 1.5
Hz, 8H), 7.34 (s, 2H), 2.60 (t, J ) 7.6, 4H), 1.62-1.52 (m, 4H),
1.38 (s, 36H), 1.37 (s, 36H), 1.35-1.21 (m, 28H), 1.18 (s, 42H),
1.169 (s, 42H), 1.165 (s, 42H), 0.89 (t, J ) 7.6 Hz, 6H); 13C
NMR (75 MHz, CDCl3) δ 151.4, 151.3, 143.2, 143.2, 142.7,
139.0 (2C), 137.23, 137.21, 137.0, 134.3, 133.2, 133.1, 131.1
(2C), 127.7, 127.6, 127.3, 127.1 (2C), 125.4, 125.1, 124.5, 123.0,
122.3, 122.2, 122.0, 121.5 (2C), 104.6, 104.5, 103.2, 100.0, 99.9,
96.4, 83.5, 83.2, 82.4, 81.0, 80.7, 80.5, 79.8, 79.5, 79.2, 78.1,
78.0, 77.1, 35.0 (2C), 32.5, 31.9, 31.5 (2C), 30.6, 29.7, 29.6,
29.56, 29.5, 29.3, 22.7, 18.7 (3C), 14.1, 11.3 (2C), 11.3; IR (KBr)
ν 2958, 2869, 2205, 2143, 1595, 1478, 836 cm-1; MS (APCI)
m/z (%) 2941.5 (M + H+, 20), 2884.2 (25), 1434.5 (100); UV
(CH2Cl2) λmax (log ꢀ) 264 (5.27), 328 (5.12), 352 (5.12), 383
(5.02).
1
yellow solid: mp 132-135 °C; H NMR (300 MHz, CDCl3) δ
7.94 (s, 2H), 7.70 (d, J ) 1.5 Hz, 2H), 7.63 (d, J ) 8.3 Hz, 2H),
7.52 (dd, J ) 8.3, 1.5 Hz, 2H), 7.49 (t, J ) 1.5 Hz, 2H), 7.40 (d,
J ) 1.5 Hz, 4H), 1.40 (s, 36H), 1.22 (s, 42H); 13C NMR (75
MHz, CDCl3) δ 151.4, 143.5, 142.8, 138.9, 133.2, 131.2, 130.6,
127.6, 127.2, 122.7, 122.4, 121.5, 104.6, 98.9, 96.4, 84.2, 81.9,
81.1, 77.5, 35.0, 31.5, 18.8, 11.4; IR (KBr) ν 2958, 2863, 2209,
2154, 1593, 1461, 876, 831, 668 cm-1; MS (APCI) m/z (%)
1387.2 (M+ + THF, 20), 1315.3 (M + H+, 20), 1291.7 (20),
1261.5 (20), 1177.8 (60), 1102.7 (30), 769.5 (20), 555.2 (100).
Linear Precursor 28. Key piece 8 (400 mg, 0.287 mmol)
was reacted with diiodoarene 27 (176 mg, 0.131 mmol) at 55
°C using general in situ deprotection/alkynylation procedure
B (22 h injection, no additional heating). The crude material
was purified by column chromatography (20:1-10:1 hexanes/
CH2Cl2) to give 28 (267 mg, 57%) as an amorphous yellow
solid: mp 150-155 °C (dec); 1H NMR (300 MHz, CDCl3) δ 7.70
(s, 2H), 7.69 (d, J ) 1.5 Hz, 2H), 7.672 (d, J ) 1.5 Hz, 2H),
7.670 (s, 2H), 7.659 (s, 2H), 7.656 (d, J ) 1.5 Hz, 2H), 7.61 (d,
J ) 8.3 Hz, 4H), 7.60 (d, J ) 8.3 Hz, 2H), 7.52 (dd, J ) 8.3,
1.5 Hz, 4H), 7.49 (dd, J ) 8.3, 1.5 Hz, 2H), 7.47 (t, J ) 1.5 Hz,
6H), 7.40-7.36 (m, 12H), 1.39 (s, 108H), 1.21 (s, 42H), 1.194
(s, 42H), 1.187 (s, 42H), 1.18 (s, 42H); 13C NMR (75 MHz,
CDCl3) δ 151.4 (3C), 143.5, 143.4, 143.3, 139.0 (2C), 138.9,
137.8, 137.2 (3C), 133.3, 133.2, 133.1, 131.1 (3C), 127.7, 127.6
(3C), 127.4, 127.2 (3C), 125.8, 125.6, 125.3, 124.6, 123.0, 122.8,
122.3 (3C), 121.5 (3C), 104.6 (2C), 104.5, 103.1, 100.2, 96.4
(3C), 84.0, 83.7, 83.3, 81.9, 81.5, 81.3, 80.7 (2C), 80.4, 80.0,
79.4, 79.1, 78.8, 78.0, 77.9, 77.8, 35.0 (3C), 31.5 (3C), 18.7 (4C),
11.4 (3C), 11.3; IR (KBr) ν 2958, 2864, 2203, 2151, 1593, 1474,
668 cm-1; UV (CH2Cl2) λmax (log ꢀ) 266 (5.40), 329 (5.28), 351
(5.28), 383 (5.27).
Tri[18]annulene 3. Acyclic precursor 25 (100 mg, 0.0340
mmol) was subjected to both general Cu-mediated cyclization
procedure C and general Pd-catalyzed cyclization procedure
D. The crude material was first dissolved in CH2Cl2, filtered
through a plug of silica gel, and concentrated in vacuo. The
resultant yellow-brown solid was triturated (10:1 hexanes/CH2-
Cl2, 2 × 5 mL) and filtered to give 3 (33 mg, 49% (procedure
C); 14 mg, 21% (procedure D)) as a bright yellow solid: mp
1
230-250 °C (dec); H NMR (500 MHz, CD2Cl2, 40 °C) δ 7.93
(d, J ) 1.5 Hz, 2H), 7.92 (d, J ) 1.5 Hz, 2H), 7.91 (s, 2H), 7.87
(s, 2H), 7.78 (d, J ) 8.0 Hz, 2H), 7.75 (d, J ) 8.0 Hz, 2H), 7.69
(dd, J ) 8.0, 1.5 Hz, 2H), 7.67 (dd, J ) 8.0, 1.5 Hz, 2H), 7.52
(br s, 4H), 7.46 (d, J ) 1.5 Hz, 8H), 7.45 (s, 2H), 2.60 (t, J )
8.0 Hz, 4H), 1.61 (quint, J ) 8.0 Hz, 4H), 1.40 (s, 72H), 1.35-
1.26 (m, 28H), 0.91 (t, J ) 8.0 Hz, 6H); 13C NMR (125 MHz,
CDCl3): δ 151.5 (2C), 143.0, 142.8, 138.4, 138.3, 136.4, 136.2,
133.2, 133.0, 132.9, 131.3, 131.1, 127.7 (2C), 127.6, 125.9,
125.8, 125.5, 125.3, 124.8, 124.1, 123.4, 123.3, 122.6, 122.5,
122.3, 121.4 (2C), 83.2, 82.7, 82.6, 81.6, 81.2, 81.1, 81.05, 81.0,
80.9, 80.8, 79.7 (3C), 79.0, 78.7, 78.6, 78.2, 78.1, 35.0 (2C), 32.4,
Linear Tetra[18]annulene 4. Acyclic precursor 28 (150
mg, 0.0412 mmol) was subjected to both general Cu-mediated
cyclization procedure C and general Pd-catalyzed cyclization
procedure D. The crude material was suspended in CH2Cl2 (50
mL) and filtered through a plug of silica gel. The annulenic
material remained on top of the bed of silica gel was scraped
off and transferred to a beaker of refluxing THF (500 mL).
10224 J. Org. Chem., Vol. 70, No. 25, 2005

2D Conjugation in Graphdiyne Nanoarchitectures
The hot solution was poured through a thin plug of silica gel
on a coarse fritted funnel and concentrated in vacuo. The
resultant yellow solid was washed with CH2Cl2 and filtered
to give 4 (28 mg, 26% (procedure C); 10 mg, 9% (procedure
D)) as a very insoluble, yellow solid: mp 220-230 °C (dec);
solubility too poor for characterization by NMR; IR (KBr) ν
2953, 2903, 2187, 2135, 1591, 1478, 1246, 827 cm-1; MS
(MALDI): m/z (%) 2386.0 (M+ + H, 100); UV (CH2Cl2) λmax
(log ꢀ) 274 (5.34), 398(5.59), 462 (5.42).
Bent Tetra[18]annulene 5. Acyclic precursor 31 (150 mg,
0.0412 mmol) was subjected to both general Cu-mediated
cyclization procedure C and general Pd-catalyzed cyclization
procedure D. The crude material was suspended in CH2Cl2 (50
mL) and filtered through a plug of silica gel. The annulenic
material remained on top of the bed of silica gel was scraped
off and transferred to a beaker of refluxing THF (500 mL).
The hot solution was poured through a thin plug of silica gel
on a coarse fritted funnel and concentrated in vacuo. The
resultant yellow solid was washed with CH2Cl2 and filtered
to give 5 (1 mg, 1% (procedure C); 33 mg, 32% (procedure D))
m-Dibromohexayne. Triyne 10 (800 mg, 1.41 mmol) was
reacted with 1,5-dibromo-2,4-diiodobenzene26 (313 mg, 0.641
mmol) at room temperature using general in situ deprotection/
alkynylation procedure B (8 h injection, 8 h additional heating).
The crude material was purified by column chromatography
(20:1 hexanes/CH2Cl2) to give the dibromoarene (700 mg, 89%)
as a yellow solid: mp 131.6-133.5 °C; 1H NMR (300 MHz,
CDCl3) δ 7.89 (s, 1H), 7.69 (d, J ) 1.5 Hz, 2H), 7.63 (s, 1H),
7.62 (d, J ) 8.3 Hz, 2H), 7.51 (dd, J ) 8.3, 1.5 Hz, 2H), 7.48 (t,
J ) 1.5 Hz, 2H), 7.39 (d, J ) 1.5 Hz, 4H), 1.39 (s, 36H), 1.21
(s, 42H); 13C NMR (75 MHz, CDCl3) δ 151.4, 143.5, 138.9,
138.4, 136.1, 133.2, 131.1, 127.6, 127.2, 126.7, 124.0, 122.7,
122.4, 121.5, 104.6, 96.3, 83.0, 80.1, 78.7, 77.4, 35.0, 31.5, 18.8,
11.3; IR (KBr) ν 2960, 2864, 2213, 2155, 1593, 1456, 1248,
1
as a bright yellow solid: mp 130-140 °C (dec); H NMR (500
MHz, CDCl3) δ 7.99 (s, 1H), 7.96 (s, 2H), 7.93-7.89 (m, 8H),
7.89 (s, 1H), 7.78 (d, J ) 8.0 Hz, 2H), 7.75 (d, J ) 8.0 Hz, 2H),
7.74 (d, J ) 8.0 Hz, 2H), 7.68-7.62 (m, 6H), 7.50 (br s, 6H),
7.43 (br s, 12H), 1.41 (s, 36H), 1.40 (s, 72H); solubility too poor
for 13C NMR; IR (KBr) ν 2963, 2902, 2860, 2762, 2710, 2472,
2451, 2187, 1591, 1476 cm-1; MS (MALDI): m/z (%) 2385.8
(M+ + H, 100); UV (CH2Cl2) λmax (log ꢀ) 230 (5.29), 395 (5.48),
408 (5.48), 446 (5.38).
Dibromo Star Precursor 33. Key piece 8 (440 mg, 0.316
mmol) was reacted with 1,2-dibromo-4,5-diiodobenzene28 (66
mg, 0.137 mmol) at 45 °C using general in situ deprotection/
alkynylation procedure B (24 h injection, 6 h additional
heating). The crude material was purified by column chroma-
tography (20:1-15:1 hexanes/CH2Cl2) to give 33 (213 mg, 55%)
as an amorphous yellow solid: mp 151-153 °C; 1H NMR (300
MHz, CDCl3) δ 7.79 (s, 2H), 7.67 (d, J ) 1.5 Hz, 2H), 7.66 (s,
2H), 7.65 (d, J ) 1.5 Hz, 2H), 7.64 (s, 2H), 7.60 (d, J ) 8.3 Hz,
2H), 7.59 (d, J ) 8.3 Hz, 2H), 7.48 (dd, J ) 8.3, 1.5 Hz, 4H),
7.46 (t, J ) 1.5 Hz, 4H), 7.37 (d, J ) 1.5 Hz, 8H), 1.38 (s, 36H),
1.37 (s, 36H), 1.18 (s, 42H), 1.17 (s, 42H), 1.16 (s, 42H); 13C
NMR (75 MHz, CDCl3) δ 151.4 (2C), 143.4, 143.3, 139.0 (2C),
137.7, 137.6, 137.3, 137.2, 133.2, 133.1, 131.1 (2C), 127.7,
127.6, 127.4, 127.1 (2C), 125.9, 125.8, 125.1, 124.6, 124.4,
122.9, 122.3 (2C), 121.5 (2C), 104.5 (2C), 103.2, 100.2, 96.4
(2C), 83.7, 83.4, 81.5, 81.3, 80.7, 79.9, 79.7, 79.4, 79.3, 79.0,
78.0, 77.9, 35.0 (2C), 31.5 (2C), 18.7 (2C), 18.6, 11.3 (2C), 11.2;
1060, 876, 830, 677 cm-1; MS (APCI) m/z (%) 1293.5 (M+
+
THF, 100), 1222.5 (M + H+, 60), 1197.3 (20), 1177.5 (20),
1147.3 (20), 601.3 (20).
m-Diiodohexayne 30. A solution of dibromoarene from
above (500 mg, 0.400 mmol) in dry THF (30 mL) in a flame-
dried flask was cooled to -78 °C under an Ar atmosphere. BuLi
(2.5 M in hexane, 0.50 mL, 1.20 mmol) was added and the
solution was warmed to -40 °C over 10 min, after which I2
(305 mg, 1.20 mmol) was added. The solution was brought to
room temperature, stirred for 15 min, and then quenched with
5% NaHSO3 (10 mL). The mixture was diluted with Et2O (30
mL) and washed with 5% NaHSO3 (2 × 30 mL) and H2O (30
mL). The organic phase was dried (MgSO4) and concentrated
in vacuo. The crude material was purified by column chroma-
tography (20:1 hexanes/CH2Cl2) to give 30 (335 mg, 62%) as a
yellow solid: mp 131.8-134.0 °C; 1H NMR (300 MHz, CDCl3)
δ 8.41 (s, 1H), 7.71 (d, J ) 1.5 Hz, 2H), 7.64 (d, J ) 8.3 Hz,
2H), 7.58 (s, 1H), 7.53 (dd, J ) 8.3, 1.5 Hz, 2H), 7.50 (t, J )
1.5 Hz, 2H), 7.41 (d, J ) 1.5 Hz, 4H), 1.41 (s, 36H), 1.23 (s,
42H); 13C NMR (75 MHz, CDCl3) δ 151.4, 147.9, 143.5, 138.9,
137.0, 133.2, 131.2, 129.1, 127.6, 127.2, 122.7, 122.4, 121.5,
104.6, 101.5, 96.3, 83.2, 82.0, 79.5, 77.5, 35.0, 31.5, 18.8, 11.3;
IR (KBr) ν 2960, 2863, 2211, 2155, 1593, 1460, 1248, 876, 830,
668 cm-1; MS (APCI) m/z (%) 1388.2 (M+ + THF, 60), 1316.5
(M + H+, 90), 1263.5 (50), 1246.5 (60), 1177.8 (100), 767.0 (20),
555.2 (40), 414.2 (90).
IR (KBr) ν 2956, 2864, 2204, 2148, 1559, 877 cm-1
.
Star Precursor 34. Dibromide 33 (200 mg, 0.071 mmol)
was reacted with triyne 10 (101 mg, 0.178 mmol) at 60 °C
using general in situ deprotection/alkynylation procedure B
(8 h injection, 2 h additional heating). The crude material was
purified by column chromatography (14:1-9:1 hexanes/CH2-
Cl2) to give 34 (95 mg, 37%) as an amorphous brown solid:
mp 145-150 °C (dec); 1H NMR (300 MHz, CDCl3) δ 7.68 (d, J
) 1.5 Hz, 2H), 7.672 (s, 2H), 7.671 (d, J ) 1.5 Hz, 2H), 7.664
(s, 2H), 7.661 (d, J ) 1.5 Hz, 2H), 7.65 (s, 2H), 7.61 (d, J ) 8.3
Hz, 4H), 7.59 (d, J ) 8.3 Hz, 2H), 7.50 (dd, J ) 8.3, 1.5 Hz,
2H), 7.49 (dd, J ) 8.3, 1.5 Hz, 4H), 7.46 (t, J ) 1.5 Hz, 6H),
7.38 (d, J ) 1.5 Hz, 4H), 7.37 (d, J ) 1.5 Hz, 8H), 1.384 (s,
36H), 1.380 (s, 36H), 1.37 (s, 36H), 1.20 (s, 42H), 1.18 (s, 42H),
1.17 (s, 84H); 13C NMR (75 MHz, CDCl3) δ 151.5, 151.4 (2C),
143.5, 143.4, 143.3, 139.0 (3C), 137.3 (2C), 137.2, 133.3, 133.2,
133.1, 131.0 (3C), 127.7, 127.6 (2C), 127.4, 127.1 (3C), 125.0,
125.8, 125.1, 124.9, 124.6, 124.5, 123.0, 122.4, 122.3 (3C), 121.5
(3C), 104.5 (3C), 103.2, 100.2, 96.4 (3C), 83.9, 83.7, 83.3, 81.9,
81.5, 81.3, 80.7, 80.6, 80.3, 79.9, 79.1, 78.9, 78.0, 77.9, 77.8,
77.2, 35.0 (3C), 31.5 (3C), 18.7 (3C), 18.6, 11.4 (3C), 11.3; IR
(KBr) ν 2954, 2866, 2269, 2203, 2156, 1653, 668 cm-1; UV
(CH2Cl2) λmax (log ꢀ) 265 (5.42), 328 (5.29), 350 (5.28), 383
(5.27).
Bent Precursor 31. Key piece 8 (400 mg, 0.287 mmol) was
reacted with diiodoarene 30 (176 mg, 0.131 mmol) at 55 °C
using general in situ deprotection/alkynylation procedure B
(22 h injection, no additional heating). The crude material was
purified by column chromatography (20:1-10:1 hexanes/CH2-
Cl2) to give 31 (275 mg, 58%) as an amorphous yellow solid:
1
mp 130-140 °C (dec); H NMR (300 MHz, CDCl3) δ 7.69 (s,
2H), 7.68 (d, J ) 1.5 Hz, 2H), 7.663 (d, J ) 1.5 Hz, 2H), 7.662
(s, 2H), 7.657 (s, 1H), 7.651 (s, 1H), 7.647 (d, J ) 1.5 Hz, 2H),
7.61 (d, J ) 8.3 Hz, 4H), 7.60 (d, J ) 8.3 Hz, 2H), 7.51 (dd, J
) 8.3, 1.5 Hz, 4H), 7.50 (dd, J ) 8.3, 1.5 Hz, 2H), 7.46 (t, J )
1.5 Hz, 6H), 7.39-7.36 (m, 12H), 1.381 (s, 72H), 1.377 (s, 36H),
1.20 (s, 42H), 1.185 (s, 42H), 1.177 (s, 42H), 1.17 (s, 42H); 13
C
NMR (75 MHz, CDCl3) δ 151.4 (3C), 143.5, 143.4, 143.3, 139.0
(2C), 138.6, 137.8, 137.2 (3C), 133.3, 133.2, 133.1, 131.2, 131.1
(3C), 127.8, 127.7 (3C), 127.4, 127.3, 127.2, 127.1, 126.0, 125.8,
125.0, 124.6, 123.0, 122.8, 122.3 (3C), 121.5 (3C), 104.6, 104.5
(2C), 103.1, 100.2, 96.4 (3C), 84.0, 83.7, 83.4, 81.9, 81.6, 81.3,
80.7, 80.6, 80.4, 80.1, 79.4, 79.1, 78.9, 78.1, 78.0, 77.8, 35.0
(3C), 31.5 (3C), 18.8 (3C), 18.7, 11.4 (2C), 11.35, 11.3; IR
(KBr) ν 2957, 2864, 2203, 2151, 1593, 1473, 668 cm-1; UV
(CH2Cl2): λmax (log ꢀ) 265 (5.36), 329 (5.24), 351 (5.22), 400
(5.21).
Star Tetra[18]annulene 6. Acyclic precursor 34 (90 mg,
0.0247 mmol) was subjected to both general Cu-mediated
cyclization procedure C and general Pd-catalyzed cyclization
procedure D. The crude material was suspended in hexanes/
CH2Cl2 (1:1, 10 mL) and filtered. The crude annulenic material
was filtered off and washed with further hexanes/CH2Cl2 (1:
1, 10 mL) to give 6 (1 mg, ca. 1% (both procedures)) as a bright
yellow solid: IR (KBr) ν 2960, 2921, 2843, 2265, 2192, 1559
cm-1; MS (MALDI): m/z (%) 2385.1 (M+, 100); UV (CH2Cl2):
λmax (log ꢀ) 230 (5.31), 414 (5.42), 428 (5.31), 448 (5.48).
J. Org. Chem, Vol. 70, No. 25, 2005 10225

Marsden and Haley
Hexa[18]annulene Precursor 35. Key piece 8 (400 mg,
0.287 mmol) was reacted with 1,2,4,5-tetraiodobenzene (37 mg,
0.064 mmol) at 55 °C using general in situ deprotection/
alkynylation procedure B (22 h injection, no additional heat-
ing). The crude material was purified by column chromatog-
raphy (20:1-10:1 hexanes/CH2Cl2) to give 35 (139 mg, 42%)
as an amorphous brown solid: mp 162-165 °C; 1H NMR (300
MHz, CDCl3) δ 7.69 (s, 2H), 7.67 (s, 4H), 7.66 (d, J ) 1.5 Hz,
8H), 7.65 (s, 4H), 7.60 (d, J ) 8.3 Hz, 4H), 7.59 (d, J ) 8.3 Hz,
4H), 7.48 (dd, J ) 8.3, 1.5 Hz, 8H), 7.46 (t, J ) 1.5 Hz, 8H),
7.37 (d, J ) 1.5 Hz, 16H), 1.38 (s, 72H), 1.37 (s, 72H), 1.18 (s,
84H), 1.17 (s, 168H); 13C NMR (75 MHz, CDCl3) δ 151.4 (2C),
143.4, 143.3, 139.0 (2C), 137.3, 137.2 (2C), 133.2, 133.1, 131.0
(2C), 127.7, 127.6, 127.3, 127.1 (2C), 125.9, 125.4, 124.6, 124.4,
122.9, 122.3 (3C), 121.5 (2C), 104.5 (2C), 103.0, 100.3, 96.4,
83.7, 83.3, 81.3, 80.9, 80.7, 80.0, 79.8, 79.4, 79.0, 78.0, 77.9,
77.2, 35.0 (2C), 31.5 (2C), 18.7 (2C), 18.6, 11.3 (2C), 11.2;
IR (KBr) ν 2958, 2864, 2208, 2146, 1473, 668 cm-1; UV (CH2-
Cl2) λmax (log ꢀ) 265 (5.35), 328 (5.24), 349 (5.22), 394 (5.22).
Acknowledgment. This work was supported by the
National Science Foundation (CHE-0414175). J.A.M.
acknowledges the NSF for an IGERT fellowship. We
thank Mojtaba Gholami (University of Alberta) for
acquisition of the MALDI data and Annie Tykwinski
for her efforts in creating the cover art.
Supporting Information Available: Synthetic details
and spectral data for 9, 12-14, and 20-22; copies of 1H or
13C NMR spectra for 3-18, 20-25, 27, 28, 30, 31, and 33-
35. This material is available free of charge via the Internet
at http://pubs.acs.org.
JO050926V
10226 J. Org. Chem., Vol. 70, No. 25, 2005