Copper-mediated domino process for the synthesis of tetraiodinated di(perylene bisimide)

Article abstract of DOI:10.1021/ol800482y

(Chemical Equation Presented) Tetraiodinated di(perylene bisimide) has been prepared from tetrabrominated perylene bisimide by the combination of Ullmann-type coupling, C-H transformation, and halogen-exchange. The crystal structure analysis confirmed tha

Full text of DOI:10.1021/ol800482y

ORGANIC
LETTERS
2008
Vol. 10, No. 12
2337-2340
Copper-Mediated Domino Process for
the Synthesis of Tetraiodinated
Di(perylene bisimide)
Yubai Shi,†,‡ Hualei Qian,†,‡ Yan Li,†,‡ Wan Yue,†,‡ and Zhaohui Wang*,†
Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic
Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China,
and Graduate School of the Chinese Academy of Sciences, Beijing 100080, China
wangzhaohui@iccas.ac.cn
Received March 3, 2008
ABSTRACT
Tetraiodinated di(perylene bisimide) has been prepared from tetrabrominated perylene bisimide by the combination of Ullmann-type coupling,
C-H transformation, and halogen-exchange. The crystal structure analysis confirmed that the aromatic core is quite distorted because of the
electrostatic repulsion and steric encumbrance of iodine substituents in the bay regions.
Perylene-3,4,9,10-tetracarboxylic acid bisimides (PBIs) have
attracted extensive interest in the past decade as excellent
n-type semiconductors with good chemical and physical
stabilities, high electron affinity, and carrier mobility.1
Various synthetic protocols have been established to prepare
PBIs and their derivatives. A diverse library of perylene
bisimides has been obtained from commercially available
dianhydride and a wide array of amines via conventional
imidization.2 Approaches have also been reported for at-
taching electron-donating or electron-withdrawing groups
directly to the perylene core, which dramatically alter the
optical and electronic properties.3
In the PBIs family, 1,7-dibromo- and tetrachloro-substi-
tuted PBIs have played important roles in the synthesis of
bay-functionalized perylene dyes, which are attractive for
application in fields such as light-harvesting arrays,4 solar
cells,5 field effect transistors,6 light-emitting diodes,7 etc.
Very recently, a series of core-fluorinated PBIs have also
been synthesized by nucleophilic halogen-exchange reactions
of the corresponding dibromo- and tetrachloro-substituted
PBIs, which achieved promising n-type semiconducting
(2) Langhals, H. Heterocycles 1995, 40, 477.
(3) (a) For seleted examples, see: Addicott, C.; Oesterling, I.; Yamamoto,
T.; Mu¨llen, K.; Stang, P. J. J. Org. Chem. 2005, 70, 797. (b) Jones, B. A.;
Ahrens, M. J.; Yoon, M.-H.; Facchetti, A.; Marks, T. J.; Wasielewski, M. R.
Angew. Chem., Int. Ed. 2004, 43, 6363. (c) You, C.-C.; Espindola, P.;
Hippius, C.; Heinze, J.; Wu¨rthner, F. AdV. Funct. Mater. 2007, 17, 3764.
(4) Kelley, R. F.; Shin, W. S.; Rybtchinski, B.; Sinks, L. E.; Wasielewski,
M. R. J. Am. Chem. Soc. 2007, 129, 3173.
† Graduate School, Chinese Academy of Sciences.
‡ Institute of Chemistry, Chinese Academy of Sciences.
(1) (a) Wu¨rthner, F. Chem. Commun. 2004, 14, 1564. (b) Newman, C. R.;
Frisbie, C. D.; da Silva Filho, D. A.; Bre´das, J.-L.; Ewbank, P. C.; Mann,
K. R. Chem. Mater. 2004, 16, 4436. (c) Chen, Z.; Debije, M. G.;
Debaerdemaeker, T.; Osswald, P.; Wu¨rthner, F. ChemPhysChem 2004, 5,
137. (d) Dehm, V.; Chen, Z.; Baumeister, U.; Prins, P.; Siebbeles, L. D. A.;
Wu¨rthner, F. Org. Lett. 2007, 9, 1085. (e) Ling, M.-M.; Erk, P.; Gomez,
M.; Koenemann, M.; Locklin, J.; Bao, Z. AdV. Mater. 2007, 19, 1123. (f)
Che, Y.; Datar, A.; Balakrishnan, k.; Zang, L. J. Am. Chem. Soc. 2007,
129, 7234.
(5) Shibano, Y.; Umeyama, T.; Matano, Y.; Imahori, H. Org. Lett. 2007,
9, 1971.
(6) Li, Y.; Wang, Z.; Qian, H.; Shi, Y.; Hu, W. Org. Lett. 2008, 10,
529.
(7) Ego, C.; Marsitzky, D.; Becker, S.; Zhang, J.; Grimsdale, A. C.;
Mu¨llen, K.; MacKenzie, J. D.; Silva, C.; Friend, R. H. J. Am. Chem. Soc.
2003, 125, 437.
10.1021/ol800482y CCC: $40.75
Published on Web 05/20/2008
2008 American Chemical Society

properties.8 Iodide was usually selected among halides due
to its higher reactivity in transition-metal-catalyzed processes
such as the Stille-, Heck-, Suzuki-, and Ullmann-type
coupling reactions9 and was expected to have the advantage
with many more synthetic possibilities of structural modi-
fications. The copper-catalyzed halogen exchange at sp2-
carbons under Ullmann-type reaction conditions10 has been
regarded as one of useful methods for the incorporation of
iodine substituents into PBIs. However, to the best of our
knowledge, there have been no precedents of such a
successful iodine exchange employing in halogenated PBIs.
The difficulties may be due to steric congestion of bulky
atoms and strong strain energies in conjugated aromatic
cores.
Amino acid promoted CuI-catalyzed Ullmann-type cou-
pling reactions have been widely employed in the formation
of C-N, C-S, C-O, and C-C bonds.11 Recently, we report
the facile synthesis of triply linked12 di(perylene bisimide)
(diPBI) 2a and tetrachloronated di(perylene bisimide) (4Cl-
diPBI) 2b (Figure 1) by coupling of tetrachloro-PBI under
present the first example of one-pot synthesis of tetraiodi-
nated di(perylene bisimide) (4I-diPBI) 5 by the combination
of modified Ullmann coupling, C-H transformation and
halogen-exchange reactions.
First, we extended the established synthetic protocol to
tetrabromo-PBIs.14 Using CuI as the reagent, L-proline as
the ligand, and K2CO3 as the base, the expected tetrabro-
minated diPBI (4Br-diPBI) 4 was obtained as a purple-black
solid by homocoupling of tetrabromo-PBI 3 at 30 °C in 20%
yield.
Generally, bromine-iodine exchange is observed at high
temperatures under modified-Ullmann conditions. Thus, it
will be feasible to incorporate four bulky iodine atoms into
the diPBI backbone by raising the reaction temperature
(Scheme 1). However, the reaction temperature should not
Scheme 1
be too high, as it may lead to the cleavage of C-halogen
bonds. Accordingly, we raised the temperature to 60 °C and
obtained the desired tetraiodinated diPBI (4I-diPBI) 5 as a
navy-blue solid in 15% yield. Using CuBr as the reagent
instead of CuI, only 4Br-diPBI was obtained by homocou-
pling of 3 at 30 and 60 °C. These results suggest that copper
iodide played multiple roles in these reactions. In particular,
excess CuI is the iodine source in halogen-exchange reac-
tions. Four bromo-iodine exchanges as well as the formation
of three new carbon-carbon bonds have been successfully
achieved in this domino-type process.15 The structures of
4Br-diPBI 4 and 4I-diPBI 5 were clearly characterized by
1H NMR, 13C NMR spectroscopy, and MALDI-TOF.
To determine the molecular structure of 4I-diPBI, crystals
of 5 suitable for single-crystal X-ray structure analysis were
obtained. The crystal structures revealed that 5 has crystal-
lographically imposed inversion symmetry.16 In 4I-diPBI 5,
owing to the electrostatic repulsion and steric encumbrance
of the iodine substituents at the bay regions and the steric
Figure 1. PBI 1, triply linked diPBI 2a, and 4Cl-diPBI 2b.
system of CuI and L-proline in different temperature.13 In
diPBI 2a, the steric encumbrance of neighboring imide rings
are expected to result in a distorted molecular structure,
which may lead to the release of strain energies. Herein, we
(8) Wu¨rthner, F.; Osswald, P.; Schmidt, R.; Kaiser, T. E.; Mansikkama¨ki,
H.; Ko¨nemann, M. Org. Lett. 2006, 8, 3765.
(9) (a) For a review, see: Leung, M.-k.; Luh, T.-Y.; Wong, K.-T. Chem.
ReV. 2000, 100, 3187. (b) For selected examples, see: Sato, J.-i.; Yamanoi,
Y.; Taira, T.; Nakamula, I.; Nishihara, H. Org. Lett. 2007, 9, 4543. (c)
Echavarren, A. M. Angew. Chem., Int. Ed. 2005, 44, 3962. (d) Ma, H.-C.;
Jiang, X.-Z. J. Org. Chem. 2007, 72, 8943.
(10) (a) Klapars, A.; Buchwald, S. L. J. Am. Chem. Soc. 2002, 124,
14844. (b) Zanon, J.; Klaparsb, A.; Buchwald, S. L. J. Am. Chem. Soc.
2003, 125, 2890.
(11) (a) Ma, D.; Zhang, Y.; Yao, J.; Wu, S.; Tao, F. J. Am. Chem. Soc.
1998, 120, 12459. (b) Zhu, W.; Ma, D. J. Org. Chem. 2005, 70, 2696. (c)
Cai, Q.; Zou, B.; Ma, D. Angew. Chem., Int. Ed. 2006, 45, 1276. (d) Lu,
B.; Ma, D. Org. Lett. 2006, 8, 6115.
(14) (a) Fan, L.; Xu, Y.; Tian, H. Tetrahedron. Lett. 2005, 46, 4443.
(b) Qiu, W.; Chen, S.; Sun, X.; Liu, Y.; Zhu, D. Org. Lett. 2006, 8, 867.
(15) (a) Poli, G.; Giambastiani, G. J. Org. Chem. 2002, 67, 9456. (b)
Lemaire, S.; Prestat, G.; Giambastiani, G.; Madec, D.; Pacini, B.; Poli, G.
J. Organomet. Chem. 2003, 687, 291.
(12) Tsuda, A.; Osuka, A. Science 2001, 293, 79.
(13) Qian, H.; Wang, Z.; Yue, W.; Zhu, D. J. Am. Chem. Soc. 2007,
129, 10664.
2338
Org. Lett., Vol. 10, No. 12, 2008

congestion between O4 (O4A) and adjacent H21 (H21A),
the two perylene rings are fused to adopt a distorted
conformation as expected with a mean plane deviation of
0.762 Å for the 40 core carbon atoms above and below the
mean plane, and with C22-C24A and C22A-C24 bonds
of 1.48 Å and a C23-C23A bond of 1.43 Å (Figure 2). The
conformation with a dihedral angle of 24.8° and 28.2°
relative to that mean plane, respectively. The distance
between O4 (O4A) and the adjacent H21 (H21A) is as short
as 2.32 Å indicating the existence of intramolecular hydrogen
bonding. Interestingly, the self-assembly ribbons consisting
of the ruffled nanographenes are observed in the crystal of
5 (Figure 3). The inversion-related pairs of 4I-diPBI mol-
Figure 3. Intermolecular interactions in the ruffled ribbons of 4I-
diPBI 5.
ecules in the crystal of 5 are linked by weak intermolecular
interactions of I1· · ·O3 3.40 Å and I1· · ·H8 3.05 Å (see the
Supporting Information).
Due to the combination of the twisted molecular
structures and the bulky diisopropylphenyl groups, 4Br-
diPBI 4 and 4I-diPBI 5 are soluble in common solvents
such as toluene, dichloromethane, and THF. 4Br-diPBI 4
and 4I-diPBI 5 display broad absorption spectra in the
region of visible light (Figure 4). In comparison with diPBI
Figure 2. Molecular structure of 4I-diPBI 5: (a) top view; (b) side
view. The solvent molecules and hydrogen atoms are omitted for
clarity.
lengths of three newly formed C-C bonds are quite similar,
as a reflection of effective conjugation over the diperylene
core. The twist angle between the two benzene rings
(C2-C3-C4-C5-C17-C18 and C6-C7-C8-C9-C13-
C14) was determined to be 35.8°, thus indicating the
extremely distorted molecular structure of 5. Notably, the
atropo-enantiomers which result from the distorted π system
are contained in the crystal of 5, separation of which is a
difficult but interesting project.17 Additionally, the neighbor-
ing imide rings are forced to adopt an up and down
Figure 4. UV-vis absorption spectra of 4Br-diPBI 4 (red line)
and 4I-diPBI 5 (black line) in CHCl3 at room temperature.
(16) Crystal Data of 5·2C6H12.The measurements were made on a
Rigaku Saturn CCD area detector with graphite monochromated Mo KR
radiation (λ 0.71073 Å) at 113 K. All calculations were performed using
the CrystalStructure crystallographic software package and SHELXL-97.
2a, the spectra of 4 and 5 are hypsochromically shifted
resulting from the introduction of the electron-withdrawing
halogen atoms. The blue solution of 5 exhibits five major
C108H98I4N4O8, M ) 2087.50, blue prisms, crystal dimension 0.24 × 0.20
× 0.10 mm, monoclinic, space group C12/c1, a ) 35.341(5) Å, b )
14.3173(14) Å, c ) 29.323(3) Å, R ) 90.00°, ꢀ ) 120.923(3)°, γ ) 90.00°,
V ) 12729(3) Å3, Z ) 4, Dc ) 1.089 g/cm3, µ ) 1.023 mm-1, θ range
1.60-25.00°. Of the 11193 reflections that were collected, 8518 were unique
(Rint ) 0.0549), GOF ) 1.097.
(17) (a) Osswald, P.; Reichert, M.; Bringmann, G.; Wu¨rthner, F. J. Org.
Chem. 2007, 72, 3403. (b) Ossward, P.; Wu¨rthner, F. J. Am. Chem. Soc.
2007, 129, 14319.
Org. Lett., Vol. 10, No. 12, 2008
2339

bands at 417, 528, 574, 618, and 677 nm, bathochromically
shifted relative to 4 which exhibits five major bands at
409, 510, 554, 606, and 661 nm.
electron-withdrawing bromine and iodine atoms, respectively.
In summary, we report the facile synthesis of 4I-diPBI 5
via the copper-mediated domino process which combines
modified Ullmann coupling, C-H transformation, and halo-
exchange reactions. X-Ray single-crystal analysis reveals that
the extremely distorted molecular structure is dominated by
the electrostatic repulsion and steric encumbrance of the
iodine substituents at the bay regions and the steric conges-
tion between the neighboring imide rings. The synthesis of
4I-diPBI opens the door to easy structural modifications on
diPBI molecular skeletons in the bay regions. Further
functionalization and investigation of bay-functionalized
triply linked diPBIs are in progress.
According to the previous studies, PBIs are fairly electron-
deficient dyes and are easily reduced to anions and dianions,
corresponding to the two imide groups in their structure.1a,18
Thus, fully conjugated diPBIs are expected to display
stronger electron-accepting ability and obtain four electrons.
Cyclic voltammetry on 4 and 5 in CH2Cl2 has been
investigated, which exhibits two reversible and two irrevers-
ible reduction waves (Table 1). The half-wave reduction
Table 1. Redox Potential (in V vs Fc/Fc+)
Acknowledgment. For financial support of this research,
we thank the National Natural Science Foundation of China
(GrantNo.20772131),973Program(GrantNo.2006CB932101,
2006CB806200), and Chinese Academy of Sciences.
a
a
a
a
E1r
E2r
E3r
E4r
diPBI 2ac
-0.46
-0.41
-0.43
-0.42
-0.73
-0.69
-0.71
-0.69
-1.49
-1.39
-1.38b
-1.32b
-1.66
-1.52
-1.51b
-1.47b
4Cl-diPBI 2bc
4Br-diPBI 4
4I- diPBI 5
Supporting Information Available: General experimental
methods, the synthesis and characterizations of compounds
a Half-wave potential. b Determined by differential pulse voltammetry
1
4 and 5, CIF file of 5, and H and 13C NMR spectra and
(DPV). c Data from ref 13.
cyclovoltammograms for 4 and 5. This material is available
free of charge via the Internet at http://pubs.acs.org.
potentials vs Fc/Fc+ are -0.43, -0.71, -1.38, and -1.51
V for 4 and -0.42, -0.69, -1.32, and -1.47 V for 5.
Compared with diPBI 2a, the reduction potentials of 4 and
5 are less negative, originating from the incorporation of the
OL800482Y
(18) Lee, S. K.; Zu, Y.; Herrmann, A.; Geerts, Y.; Mu¨llen, K.; Bard,
A. J. J. Am. Chem. Soc. 1999, 121, 3513.
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Org. Lett., Vol. 10, No. 12, 2008