Palladium-catalyzed direct phenylation of perylene: Structural and optical properties of 3,4,9-triphenylperylene and 3,4,9,10-tetraphenylperylene

Article abstract of DOI:10.1016/j.tet.2013.01.037

We have developed one-step synthesis of multiphenylperylenes from perylene through palladium-catalyzed oxidative C-H/C-B coupling using phenylboroxin as a phenyl source. The combination of Pd(OAc)₂ as a catalyst and o-chloranil as an oxidant is the key for direct C-H arylation of perylene. The X-ray crystallography of 3,4,9-triphenylperylene (3) and 3,4,9,10- tetraphenylperylene (4) revealed twisted structures of perylene core caused by steric repulsion of neighboring phenyl groups. Compounds 3 and 4 showed red shift in both absorption and fluorescence spectra compared to perylene whereas absolute fluorescence quantum yields are similarly high (Φ_F=0.94) .

Full text of DOI:10.1016/j.tet.2013.01.037

Tetrahedron xxx (2013) 1e4
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Palladium-catalyzed direct phenylation of perylene: structural and optical
properties of 3,4,9-triphenylperylene and 3,4,9,10-tetraphenylperylene
,b,
Katsuaki Kawasumi a, Kenji Mochida a, Yasutomo Segawa a, Kenichiro Itami a
*
a Department of Chemistry, Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan
b Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya 464-8602, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
We have developed one-step synthesis of multiphenylperylenes from perylene through palladium-
catalyzed oxidative CeH/CeB coupling using phenylboroxin as a phenyl source. The combination of
Pd(OAc)2 as a catalyst and o-chloranil as an oxidant is the key for direct CeH arylation of perylene. The
X-ray crystallography of 3,4,9-triphenylperylene (3) and 3,4,9,10-tetraphenylperylene (4) revealed
twisted structures of perylene core caused by steric repulsion of neighboring phenyl groups. Compounds
3 and 4 showed red shift in both absorption and fluorescence spectra compared to perylene whereas
absolute fluorescence quantum yields are similarly high (FF¼0.94).
Received 28 November 2012
Received in revised form 10 January 2013
Accepted 14 January 2013
Available online xxx
Keywords:
CeH arylation
Palladium catalyst
Perylene
Ó 2013 Published by Elsevier Ltd.
Photophysical properties
1. Introduction
flattened.5c Furthermore, we have demonstrated two-step
p-ex-
tension of PAHs through the sequence of direct arylation and
Polycyclic aromatic hydrocarbons (PAHs) are of significant
importance in the field of materials science and nanocarbon
chemistry not only because of their electronic and photophysical
properties but also because they can be considered as small seg-
ments of graphenes. Arylation of PAHs is a fundamental reaction
to tune the properties of PAHs.1 Typical method for arylation of
PAHs can be categorized into halogenation of PAHs followed by
Pd-catalyzed cross-coupling reactions2 or Ir-catalyzed CeH bor-
ylation of PAHs followed by Pd-catalyzed cross-coupling with aryl
halides.3 Although direct CeH arylation of PAHs is widely sought
by materials science, there have been few reports on CeH/CeM
coupling (M¼Sn, Si) of PAHs4 except our work. Recently, we have
discovered that Pd(OAc)2/o-chloranil catalyst can promote a CeH
arylation of PAHs with arylboron compounds (CeH/CeB coupling)
(Fig. 1).5 The CeH arylation takes place regioselectively at the
K-region of pyrene, phenanthrene, and benzo[a]anthracene.5a The
Pd(OAc)2/o-chloranil catalyst system is also applicable to CeH/CeB,
CeH/CeSi and CeH/CeH coupling of fluoranthene with high
regioselectivity.5b More recently, we found that corannulene,
a bowl-shaped PAH having K-regions, can be subjected to the CeH
arylation under the influence of Pd(OAc)2/o-chloranil to furnish
decaarylcorannulenes, in which corannulene cores are unusually
dehydrogenative cyclization.5a,b
* Corresponding author. Tel./fax: þ81 52 788 6098; e-mail address: itami.
kenichiro@a.mbox.nagoya-u.ac.jp (K. Itami).
Fig. 1. Palladium-catalyzed direct CeH arylation of PAHs.
0040-4020/$ e see front matter Ó 2013 Published by Elsevier Ltd.
http://dx.doi.org/10.1016/j.tet.2013.01.037
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2
K. Kawasumi et al. / Tetrahedron xxx (2013) 1e4
In this paper we report on the arylation of perylene with
2.2. X-ray crystal structures of 3,4,9-triphenylperylene and
3,4,9,10-tetraphenylperylene
phenylboroxin catalyzed by Pd(OAc)2/o-chloranil. Perylene de-
rivatives, representative of which is perylene bisimides, have found
various applications as optical and electrical materials.6,7 However,
functionalization of perylenes are still limited to halogenation1 and
borylation.3a Thus, the development of a direct and selective per-
ylene arylation protocol is highly called for and should have a great
impact in materials science. The outcome of our extensive in-
vestigations is the first one-step synthesis of multiphenylperylenes
from perylene through palladium-catalyzed oxidative CeH/CeB
coupling using phenylboroxin as a phenyl source. Structural and
photophysical properties of tri- and tetraphenylperylenes are also
discussed.
The structures of 3 and 4 were unambiguously confirmed by
X-ray crystallography. The X-ray crystal structures of 3 and 4 are
shown in Fig. 2. Center of symmetry is located on the center of
molecule 4. It is clearly seen that perylene core of 3 is twisted with
the torsion angle of around 10ꢀ owing to steric repulsions between
two phenyl rings. Interestingly, perylene core of 4 is not as twisted
as 3, but rather adopts interesting bent structure as a whole. The
phenyl groups at 3- and 10-positions are directed toward the same
direction perpendicular to the perylene plane, whereas the phenyl
groups at 4- and 9-positions are directed toward other direction.
The distances between ipso-positions of neighboring phenyl rings
ꢀ
ꢀ
are 2.996(7) A for 3 and 2.961(2)/2.952(2) A for 4, which indicate
that steric repulsions of phenyl rings of 3 and 4 are similar. In the
solid state of both 3 and 4, molecules are located far from each
other (longer distances than sum of van der Waals radii). These
2. Results and discussion
results indicate that there is no significant intermolecular
interactions in 3 and 4 due to the steric hindrance of phenyl
pep
2.1. Direct multi-phenylation of perylene
groups.
We began by applying our standard conditions of CeH/CeB
coupling to pyrene.5a Thus, the treatment of perylene (1 equiv)
and phenylboroxin (1 equiv) in the presence of Pd(OAc)2 (5 mol %)
and o-chloranil (2 equiv) in 1,2-dichloroethane at 80 ꢀC produced
3-phenylperylene (1) in 17% isolated yield (Scheme 1). Concur-
rently, di-, tri-, and tetraphenylated perylenes (2, 3, and 4) were
also obtained in 24%, 11%, and 0.7% yield, respectively. The yield of
diphenylperylene 2 was determined as the mixture of isomers.
The CeH/CeB coupling took place selectively at the peri-positions
(C3, C4, C9, and C10) of perylene similar to the C3-selective ary-
lation of fluoranthene, which we previously reported.5b The yields
of 3 and 4 did not increase dramatically even larger amounts of
phenylboroxin (1.67 equiv), Pd(OAc)2 (20 mol %), and o-chloranil
(4 equiv) were employed (Scheme 1, yields shown in parentheses).
These results indicate that the third and fourth phenylation re-
actions are relatively slow due to steric hindrance of phenyl
groups on the peri-positions. The structures of phenylated per-
ylenes were identified by 1H NMR, 13C NMR, and HRMS.
Fig. 2. ORTEP drawings of 3 (top) and 4 (bottom) with 50% thermal ellipsoids. All
hydrogen atoms are omitted for clarity. One of two independent molecules of 4 is
shown.
2.3. Photophysical properties of 3,4,9-triphenylperylene and
3,4,9,10-tetraphenylperylene
The electronic absorption and fluorescence properties of 3 and
4
in dichloromethane were investigated, including UVevis
absorption, fluorescence spectra, and fluorescence quantum
yields. The absorption and fluorescence spectra of 3 (blue) and 4
(red) are shown in Fig. 3 and the data are summarized in Table 1.
As a reference, the UVevis absorption of parent perylene is also
shown (gray) in Fig. 3. The absorption spectra of 3 and 4 are
broadened compared with that of perylene. The absorption
coefficients (ε) of 3 and 4 were determined to be 3.7ꢁ104 and
4.2ꢁ104 Mꢂ1 cmꢂ1, respectively. As somewhat expected, we
observed bathochromic shift in absorption maximum (lmax) as the
number of phenyl groups increased; 436 nm (perylene) <473 nm
(3) <486 nm (4). Both 3 and 4 showed intense photoluminescence
in solution with the emission maximum wavelengths (lem) of
500 nm and 520 nm, respectively. The absolute fluorescence
quantum yields (FF) of 3 and 4 in dichloromethane were found to
be extremely high (0.94 for both compounds). Although X-ray
crystallographic analysis clearly showed the structural difference
between 3 and 4, significant difference of absorption and fluo-
rescence between 3 and 4 was not observed. It is presumed that
the two conformations of perylene cores, twisted or planar, are
interconverted rapidly in solution state.
Scheme 1. Pd-catalyzed CeH/CeB coupling of perylene and phenylboroxin. Yields are
isolated yields. Values in parenthesis are the yields resulted from following conditions:
Pd(OAc)2 20 mol %, phenylboroxin 1.67 equiv, o-chloranil 4 equiv.
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K. Kawasumi et al. / Tetrahedron xxx (2013) 1e4
3
magnetic resonance (NMR) spectra were recorded on a JEOL
ECS-600 (1H 600 MHz, 13C 150 MHz) spectrometer. Chemical shifts
for 1H NMR are expressed in parts per million (ppm) relative to
tetramethylsilane (
expressed in ppm relative to CDCl3 (
d
0.0 ppm). Chemical shifts for 13C NMR are
d
77.0 ppm). Data are reported
as follows: chemical shift, multiplicity (s¼singlet, d¼doublet,
t¼triplet, m¼multiplet), coupling constant (hertz), and
integration.
4.2. Procedure for direct CeH phenylation of perylene
A solution of Pd(OAc)2 (11.2 mg, 50 mmol, 5.0 mol %), o-chloranil
(490 mg, 2.0 mmol, 2.0 equiv), perylene (252 mg, 1.0 mmol,
1.0 equiv), and phenylboroxin (311 mg 1.0 mmol, 1.0 equiv) in dry
1,2-dichloroethane (20 mL) was stirred at 80 ꢀC for 2 h. After
cooling the reaction mixture to room temperature, the mixture was
passed through a short pad of silica gel (CH2Cl2,100 mL). The filtrate
was then evaporated and the residue was purified by silica gel
column chromatography (hexane/CH2Cl2¼100:0 to 85:15) to obtain
3-phenylperylene (1) (56.2 mg 17%), mixture of diphenylperylene
isomers (2) (97.5 mg, 24%), 3,4,9-triphenylperylene (3) (54.2 mg,
11%), and 3,4,9,10-tetraphenylperylene (4) (3.7 mg, 0.7%).
Fig. 3. UVevis absorption (solid line) and fluorescence spectra (broken line) of per-
ylene (gray),
normalized.
3 (blue) and 4 (red) in dichloromethane. Fluorescence spectra are
Table 1
Photophysical data for perylene, 3, and 4a
Compound
Absorption
Fluorescence
b
d
ε [Mꢂ1 cmꢂ1
]
lmax [nm]b
lem [nm]c
FF
Perylene
3
4
3.2ꢁ104
3.7ꢁ104
4.2ꢁ104
438
473
486
448
500
520
0.97e
0.94
0.94
4.3. Compound data of products
4.3.1. 3-Phenylperylene (1). 1H NMR (600 MHz, CDCl3/CS2¼1:1)
a
In dichloromethane.
Only the longest absorption maxima are given.
Emission maxima upon excitation at the absorption maximum wavelengths
d
8.20 (d, J¼8.4 Hz, 1H), 8.18 (d, J¼6.6 Hz, 2H), 8.17 (d, J¼6.6 Hz, 1H),
b
c
7.73 (d, J¼7.8 Hz, 1H), 7.66 (d, J¼7.8 Hz, 2H), 7.49e7.45 (m, 6H),
7.42e7.39 (m, 3H); 13C NMR (150 MHz, CDCl3/CS2¼1:1)
d 140.6,
(
lmax).
d
Absolute fluorescence quantum yields determined by a calibrated integrating
139.9, 134.6, 132.9, 131.33, 131.28, 131.2, 130.5, 129.9, 129.0, 128.6,
128.3, 127.74, 127.70, 127.65, 127.3, 126.6, 126.45, 126.0, 120.31,
120.28, 120.1, 119.9. HRMS (DART, ESIþ) m/z calcd for C26H17
[MþH]þ: 329.1330, found: 329.1329. Mp: 197.4e199.4 ꢀC.
sphere system within ꢃ3% errors.
e
A value reported in Ref. 8.
3. Conclusion
4.3.2. 3,4,9-Triphenylperylene (3). 1H NMR (600 MHz, CDCl3/
CS2¼1:1)
d
8.24 (d, J¼7.8 Hz, 1H), 8.23 (d, J¼7.8 Hz, 1H), 8.21
We have developed one-step synthesis of multiphenylperylenes
from perylene through palladium-catalyzed oxidative CeH/CeB
coupling using phenylboroxin as a phenyl source. The combination
of Pd(OAc)2 as a catalyst and o-chloranil as an oxidant is the key for
direct CeH arylation of perylene. Although the yield of each phe-
nylated perylene is not high, our newly developed method repre-
sents the most step-economical way to supply arylated perylenes.
The X-ray crystallography of 3,4,9-triphenylperylene (3) and
3,4,9,10-tetraphenylperylene (4) revealed twisted structures of
perylene core caused by steric repulsion of neighboring phenyl
groups. Compounds 3 and 4 showed red shift in both absorption
and fluorescence spectra compared to perylene whereas absolute
fluorescence quantum yields are similarly high (FF¼0.94). Further
(d, J¼7.8 Hz, 1H), 8.19 (d, J¼7.8 Hz, 1H), 7.74 (d, J¼7.8 Hz, 1H),
7.49e7.45 (m, 4H), 7.42e7.37 (m, 5H), 6.96 (d, J¼7.2 Hz, 4H), 6.89
(t, J¼7.2 Hz, 4H), 6.84 (d, J¼7.2 Hz, 2H); 13C NMR (150 MHz, CDCl3/
CS2¼1:1)
d 142.9, 140.4, 140.01, 139.98, 139.6, 132.5, 131.5, 131.4,
130.61, 130.59, 130.56, 130.5, 130.4, 129.8, 129.4, 128.4, 128.2, 127.8,
127.2, 126.6, 125.8, 125.7, 120.4, 120.3, 120.1, 120.0. HRMS (DART,
ESIþ) m/z calcd for C38H25 [MþH]þ: 481.1956, found: 481.1955. Mp:
251.1e253.1.
4.3.3. 3,4,9,10-Tetraphenylperylene (4). 1H NMR (600 MHz, CDCl3/
CS2¼1:1)
d
8.30 (d, J¼7.8 Hz 4H), 7.43 (d, J¼7.8 Hz 4H), 7.00
(d, J¼6.6 Hz, 8H), 6.91 (t, J¼7.2 Hz, 8H), 6.87 (t, J¼7.4 Hz, 4H); 13C
NMR (150 MHz, CDCl3/CS2¼1:1)
d 142.8, 140.0, 131.7, 130.7, 130.4,
investigation on the sequential
p-extension of perylene for the
130.1, 129.4, 127.2, 125.7, 120.4. HRMS (DART, ESIþ) m/z calcd for
concise transformation of rylenes9 is now ongoing.
C
44H29 [MþH]þ: 557.2269, found: 557.2243. Mp: >300 ꢀC.
4. Experimental section
4.1. General
4.4. X-ray crystal structure analysis of 3 and 4
Intensity data were collected at 103(2) K on a Rigaku Single
Crystal CCD X-ray Diffractometer (Saturn 70 with MicroMax-007)
ꢀ
All materials including dry solvents were obtained from
commercial suppliers and used without further purification. Phe-
nylboroxin was prepared from phenylboronic acid by reported
procedure.10 All reactions were performed with dry solvents under
an atmosphere of argon in dried glassware with standard vacuum-
line techniques. Work-up and purification procedures were carried
out with reagent-grade solvents under air.
High-resolution mass spectra (HRMS) were measured on
a JMS-T100TD instrument (DART). Melting points were measured
on a MPA100 Optimelt automated melting point system. Nuclear
with graphite-monochromated Mo K
a
radiation (l¼0.71070 A).
The structure was solved by direct methods (SIR-97)11 and refined
by the full-matrix least-squares techniques against F2 (SHELXL-
97).12 All non-hydrogen atoms were refined anisotropically.
Hydrogen atoms were placed using AFIX instructions.
Details of the crystal data and a summary of the intensity
data collection parameters for 3 (CCDC 881424): a total 14,954
reflections were corrected, of which 3893 were independent
reflections (Rint¼0.0881). C38H24
,
FW¼480.57, crystal size
0.10ꢁ0.03ꢁ0.01 mm3, orthorhombic, space group Pca21.
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4
K. Kawasumi et al. / Tetrahedron xxx (2013) 1e4
3
ꢀ
ꢀ
ꢀ
ꢀ
a¼9.162(2) A, b¼18.927(5) A, c¼13.446(3) A, V¼2331.8(10) A , Z¼4,
Supplementary data
Dcalcd¼1.369 g/cm3. The refinement converged to R1¼0.0689,
wR2¼0.1584 (I>2
GOF¼1.063.
s
(I)), R1¼0.1102, wR2¼0.1939 (for all data),
Copies of 1H NMR and 13C NMR spectra of compounds 1, 3, 4 are
available. Supplementary data related to this article can be found
online athttp://dx.doi.org/10.1016/j.tet.2013.01.037.
Details of the crystal data and a summary of the intensity data
collection parameters for 4 (CCDC 881425): a total 17,839 reflections
were corrected, of which 4943 were independent reflections
(Rint¼0.0403). C44H28, FW¼556.66, crystal size 0.15ꢁ0.05ꢁ0.05 mm3,
References and notes
ꢀ
ꢀ
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This work was supported by the Funding Program for Next
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