Functional 2-benzyl-1,2-dihydro[60]fullerenes as acceptors for organic photovoltaics: Facile synthesis and high photovoltaic performances

Article abstract of DOI:10.1016/j.tet.2012.11.099

A new series of functional 2-benzyl-1,2-dihydro[60]fullerenes, BnHCs, were synthesized efficiently via co-catalyzed selective monofunctionalization of C₆₀ with functional benzyl bromides. Photophysical and electrochemical properties of the new

Full text of DOI:10.1016/j.tet.2012.11.099

Accepted Manuscript
Functional 2-benzyl-1,2-dihydro[60]fullerenes as acceptors for organic photovoltaics:
facile synthesis and high photovoltaic performances
Shirong Lu, Tienan Jin, Takeshi Yasuda, Islam Ashraful, Md. Akhtaruzzaman,
Liyuan Han, Khalid A. Alamry, Samia A. Kosa, Abdullah Mohamed Asiri, Yoshinori
Yamamoto
PII:
S0040-4020(12)01817-0
10.1016/j.tet.2012.11.099
TET 23810
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 1 November 2012
Revised Date: 28 November 2012
Accepted Date: 29 November 2012
Please cite this article as: Lu S, Jin T, Yasuda T, Ashraful I, Akhtaruzzaman M, Han L, Alamry KA, Kosa
SA, Asiri AM, Yamamoto Y, Functional 2-benzyl-1,2-dihydro[60]fullerenes as acceptors for organic
photovoltaics: facile synthesis and high photovoltaic performances, Tetrahedron (2013), doi: 10.1016/
j.tet.2012.11.099.
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Functional 2-benzyl-1,2-
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dihydro[60]fullerenes as acceptors for
organic photovoltaics: facile synthesis and
high photovoltaic performances
Shirong Lu, Tienan Jin , Takeshi Yasuda, Islam Ashraful, Md. Akhtaruzzaman, Liyuan Han, Khalid A. Alamry,
Samia A. Kosa, Abdullah Mohamed Asiri and Yoshinori Yamamoto

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1
Tetrahedron
journal homepage: www.elsevier.com
Functional 2-benzyl-1,2-dihydro[60]fullerenes as acceptors for organic photovoltaics:
facile synthesis and high photovoltaic performances
Shirong Lua, Tienan Jina, , Takeshi Yasudab, Islam Ashrafulb, Md. Akhtaruzzamanc, Liyuan Hanb, Khalid
A. Alamryd, Samia A. Kosad, Abdullah Mohamed Asirid and Yoshinori Yamamotoa,d,
a WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aobaku, Sendai 980-8577, Japan
b Photovoltaic Materials Unit, National Institute for Materials Science, Tsukuba 305-0047, Japan
c Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
d Chemistry Department, Faculty of Science, and Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah,
Saudi Arabia
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
A new series of functional 2-benzyl-1,2-dihydro[60]fullerenes, BnHCs, were synthesized
efficiently via Co-catalyzed selective monofunctionalization of C60 with functional benzyl
bromides. Photophysical and electrochemical properties of the new BnHCs were investigated.
PSCs based on 2-MeO-4-CO2Me-BnHC as new acceptor and P3HT as donor showed a power
conversion efficiency of 3.75% which is comparable to that of PC61BM under the same device
conditions.
Available online
Keywords:
2009 Elsevier Ltd. All rights reserved.
fullerene acceptor
mono-functional benzyl
catalytic synthesis
polymer solar cells
power conversion efficiency
(poly(3-hexylthiophene)) than that of PCBM.4 To date, PCEs of
7-8% have already been reached for the PSCs based on the
1. Introduction
Functional fullerenes are one of the most promising acceptors
for the low band-gap polymer solar cells (PSCs) due to their high
electron affinity and high electron mobility, and tunable
solubility, energy level and packing structure.1,2 Among them,
PC61BM ([6,6]-phenyl-C61-butyric acid methyl ester) and its C70
analogue PC71BM are the most representative acceptor materials
which offer good solubility and high electron mobility.3 In
addition, most recently some new fullerene derivatives have been
synthesized for PSC applications. For instance, bisfunctionalized
56 π-electron fullerenes such as bisPCBM, indene-C60 bisadduct,
dihydronaphthyl-C60 bisadduct, di(4-methylphenyl)-methano-C60
bisadduct, 1,2-dihydromethano (CH2)-modified PC61BM, and
thieno-o-quinodimethane-C60 bisadduct showed higher power
conversion efficiencies (PCEs) for the PSCs based on P3HT
innovative low band-gap polymers as electron donors and
PC61BM or PC71BM as an electron acceptor by optimization of
the nanostructured morphology.5 The design and efficient
synthesis of new fullerene acceptors to replace PCBM are still
needed to be compatible with the rapidly developed polymer
donors for application in PSCs.
On the other hand, monofunctional fullerene derivatives have
been paid less attention for PSCs application, while recently
some advanced monofunctionalizations of fullerenes have been
reported.6 Recently, Lu and Tao et al synthesized new mono-
fluorene-substituted hydrofullerene (C60F) via Rh-catalyzed
arylation.7 However, even C60F showed similar LUMO energy
level to that of PC61BM, it gave much lower PCE than that of
———
Corresponding author. Tel.: +81-22-217-6177; fax: +81-22-217-5979; e-mail: tjin@m.tohoku.ac.jp
Tel.: +81-22-217-6164; fax: +81-22-217-5979; e-mail: yoshi@m.tohoku.ac.jp

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Tetrahedron
PC61BM when blended with PCDTBT (poly-(2,7-carbazole)
The functional BnHCs possess high solubility in chloroform,
toluene, and ODCB comparable with that of PC61BM.
derivative). Most recently, we reported an efficient Co-catalyzed
monofunctionalization of C60 with active alkyl bromides.6a
Various hydrofullerenes substituted with benzyl, allyl, and
propargyl groups were obtained in good to high yields with high
monoselectivity. Interestingly, during our study on
electrochemical properties of these fullerene derivatives, we
found that the LUMO level of 2-benzyl-1,2-dihydro[60]fullerene
(BnHC) is almost similar to that of PC61BM. This result led us to
further design and synthesis of new BnHC derivatives for
application in PSCs. Herein, we report the facile synthesis of a
novel series of functional BnHCs, characterization of their
photophysical and electrochemical properties, and evaluation of
their PSC performances (Scheme 1). Functional BnHCs were
synthesized
efficiently
through
the
Co-catalyzed
monofunctionalization of C60 with commercially available benzyl
bromide derivatives under mild reaction conditions. Among
them, the PSC based on 2-MeO-4-CO2Me-BnHC as acceptor
showed a comparable PCE with the reference acceptor PC61BM
under the same device conditions blending with P3HT as donor.
Scheme 1. Co-catalyzed mono-functionalization of C60 for
synthesis of BnHCs.
The UV-vis absorption spectra of the BnHCs and the
reference PC61BM were measured in chloroform (Fig. 1). The
absorption pattern of BnHCs in the 250-280 nm is not influenced
by the varied functional groups on phenyl ring, and similar
characteristic absorption as PC61BM are observed. BnHCs exhibit
slightly enhanced absorption in the 280-330 nm region than that
of PC61BM, especially for 2-MeO-4-CO2Me-BnHC. In the
visible region from 400-500 nm, BnHCs show the same
absorption spectra regardless of the varied functional groups,
while they are stronger than that of PC61BM (Fig. 1, inset).
2. Results and discussion
BnHCs were prepared in one-step with good yields through
our previously reported Co-catalyzed selective mono-benzylation
of pristine C60 with functional benzyl bromides (Scheme 1).8a The
reaction proceeds in the presence of CoCl2dppe (dppe:
diphenylphosphinoethane) catalyst and Mn reductant under argon
atmosphere and neutral conditions at room temperature. The poor
solubility BnHC prepared from benzyl bromide limits its
application in solution-process solar cells. Several BnHC
derivatives with various functional groups on phenyl ring were
synthesized to improve their solubility as well as to investigate
the influence of substituents on the energy levels and PSC
performances. As shown in Scheme 1, a series of BnHCs such as
4-MeO-BnHC, 4-CO2Me-BnHC, 3-CO2Me-BnHC, and 2-MeO-
4-CO2Me-BnHC, were synthesized using 200-500 mg scale of
C60 in 52-60% yields. In order to investigate the influence of
solubility on morphology and performance in PSC device, the
G3-dendrimer-substituted G3-BnHC was also prepared which
has an excellent solubility in various organic solvents
(>90mg/mL in o-dichlorobenzene (ODCB)). It is also worth
noting that all the chemicals including C60, functional benzyl
bromides, and catalyst are commercially available. Although a
very small amount of inseparable multiadducts was produced
together with the recovered C60 (20-30%) in this large scale
synthesis, the products were simply purified by silica gel
chromatography using toluene and hexane as the eluents,
especially for 4-CO2Me-BnHC, 3-CO2Me-BnHC, and 2-MeO-4-
CO2Me-BnHC due to the good polarity of methyl ester group,
indicating its easy handling and low cost synthetic procedure.
Table 1. Electrochemical reduction potentialsa and LUMO
energy levelsb of BnHCs and PC61BM.
compound
E1/21/V
-0.61
-0.59
-0.61
E1/22/V
-1.01
-0.98
-0.98
-1.01
-1.49
-0.98
E1/23/V
-1.56
-1.48
-1.46
-1.56
-1.49
-1.48
LUMO/eV
-3.55
4-MeO-BnCH
4-CO2Me-BnHC
3-CO2Me-BnHC
-3.57
-3.55
2-MeO-4-CO2Me-BnHC -0.62
-3.54
G-3-BnHC
PC61BM
-0.60
-0.58
-3.56
-3.58
a Potential values are versus Ag/AgCl reference electrode; reduction potential
of ferrocene (0.64 V) is versus Ag/AgCl.
b The LUMO energy levels were estimated using the following equation:
LUMO = -(4.80+E1/21-0.64) eV.
The LUMO energy levels of BnHCs and PC61BM were
evaluated by the first reduction potentials measured by cyclic
voltammetry (CV) (Fig. 1b and Table 1). BnHCs exhibit three
pseudo-reversible reduction waves in the same manner as that of

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Figure 1. Photophysical and electrochemical properties of BnHCs and PC61BM, (a) UV-vis absorption in chloroform, (b) cyclic voltammograms in ODCB
solution with Bu4NBF4 as a supporting electrolyte (vs Ag/Ag+).
Figure 2. (a) Current density-voltage curves and (b) incident photon-to-current conversion efficiency.
PC61BM. As aforementioned, BnHC without functional groups
on phenyl ring shows a negative shift of the first reduction
potential (E1/21, -0.59 V) by 10 mV compared to PC61BM. The
BnHCs having an electron-donating or/and an electron-
withdrawing group on phenyl ring, such as 4-MeO-BnHC, 4-
CO2Me-BnHC, 3-CO2Me-BnHC, 2-MeO-4-CO2Me-BnHC, and
obtained for 2-MeO-4-CO2Me-BnHC device than that of the
PC61BM device, the Voc value of 0.63 V is higher. The PCEs for
other BnHCs with monofunctional group on phenyl ring such as
4-MeO-BnHC, 4-CO2Me-BnHC, and 3-CO2Me-BnHC are 2.39,
2.80, and 2.84%, respectively, which are lower than that of 2-
MeO-4-CO2Me-BnHC. Comparing with the PC61BM device, the
small increased LUMOs of BnHCs did not show significantly
improved Voc, and the lower Jsc and FF result in the lower or
similar PCEs. In sharp contrast, although the PSC based on the
bulky dendrimer-incorporated acceptor G3-BnHC showed a
moderate Voc value of 0.56 V, the Jsc and FF are much lower than
that of other BnHCs devices, probably the bulky G3 dendrimer
functional group inhibits the stacking of C60 cages and hence
decreases the electron transfer. The higher IPCE values of both
2-MeO-4-CO2Me-BnHC and PC61BM devices in the region from
350 to 650 nm than other BnHCs devices contribute to their
higher Jsc values, suggesting their rather efficient photon-to-
electron conversion processes.
1
G-3-BnHC show a similar or slightly negative shifted E1/2 than
PC61BM. The relatively higher LUMO energy levels of BnHCs
are attributed to the presence of two sp3 carbons between the aryl
group and the C60 cage that block the conjugation channel
between both units. Since the open-circuit voltage (Voc) of PSCs
has an association with the energy difference between the LUMO
of acceptor and the HOMO of donor,8 it is expected that these
soluble new BnHCs should be applicable as acceptors in PSCs.
PSCs based on new BnHCs as acceptors and the
representative polymer P3HT as donor with thickness of about
200 nm were fabricated and characterized. The photovoltaic
parameters for ITO/PEDOT:PSS(40 nm)/P3HT:BnHCs(w/w =
1/1)/LiF (1 nm)/Al (80 nm) under illumination with 100 mW cm-
Table 2. PSC performances based on P3HT and BnHCs
2
of AM 1.5 are summarized in Table 2. For comparison, the
acceptors (w/w = 1/1)a
reference PSC device based on P3HT/PC61BM was also
fabricated. Fig. 2a shows the J-V curves and Fig. 2b shows the
incident photon-to-current conversion efficiency (IPCE) spectra
of the PSCs. Among the new BnHCs based devices, the 2-MeO-
4-CO2Me-BnHC device displays the highest PCE of 3.75%,
which is comparable to that of the reference PC61BM, 3.78%. It
can be seen that, although the slightly lower Jsc and FF were
acceptor
Voc
Jsc
FF
PCE
[%]
[V]
[mAcm-2]
[%]
48.4
55.7
53.2
4-MeO-BnCH
0.60
0.60
0.61
8.24
2.39
2.80
2.84
4-CO2Me-BnHC
3-CO2Me-BnHC
8.38
8.76

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Tetrahedron
2-MeO-4-CO2Me-BnHC
0.63
0.56
0.60
9.66
0.66
9.86
61.6
36.6
64.0
3.75
0.13
3.78
P3HT as donor showed the highest PCE of 3.75% which is
comparable to that of the reference acceptor PC61BM. The high
PCE is attributed to the improved nanoscale morphology of blend
film rather than the slightly increased LUMO level. Considering
the facile and low-cost synthetic method together with the high
PSC performance, the new 2-MeO-4-CO2Me-BnHC should be a
promising candidate for employing as an electron acceptor in the
PSC devices. Further investigations on molecular engineering of
BnHC series, morphology optimization, and blending with other
polymers to increase the PSC performances are in progress.
G-3-BnHC
PC61BM
a Blend film was prepared using P3HT (20 mg) and BnHCs (20 mg) in 1,2-
dichlorobenzene (1 mL); annealing temperature is 110 oC (10 min).
4. Experimental section
4.1. General information
1H NMR and 13C NMR spectra were recorded on JEOL
1
JMTC-270/54/SS (JASTEC, 400 MHz) spectrometers. H NMR
spectra are reported as follows: chemical shift in ppm (δ) relative
to the chemical shift of CDCl3 at 7.26 ppm, integration,
multiplicities (s = singlet, d = doublet, t = triplet, q = quartet, m =
multiplet and br = broadened), and coupling constants (Hz). 13C
NMR spectra reported in ppm (δ) relative to the central line of
triplet for CDCl3 at 77 ppm. High-resolution mass spectra were
obtained on a BRUKER APEXIII spectrometer. Preparative
recycling HPLC was used a LC-2000 Plus instrument equipped
with a Buckyprep column (4.6 mm x 250 mm, nakarai Tesque).
HPLC analysis performed using toluene as an elution at 0.6
o
o
ml/min flow rate, detection at 320 nm in 4 C or 18 C. Column
chromatography was carried out employing Silica gel 60 N
(spherical, neutral, 40~100 µm, KANTO Chemical Co.).
Analytical thin-layer chromatography (TLC) was performed on
0.2 mm precoated plate Kieselgel 60 F254 (Merk). The
thicknesses of the blend films and PEDOT:PSS layers were
measured using an automatic micro figure measuring instrument
(Surfcorder ET200, Kosaka Laboratory Ltd.). The current
density–voltage (J–V) curves were measured using an ADCMT
6244 DC Voltage Current Source/Monitor under AM 1.5 solar-
simulated light irradiation of 100 mW/cm2 (OTENTO-SUN III,
Bunkoh-Keiki Co.). IPCE was measured using a CEP-2000
system (Bunkoh-Keiki Co., Ltd.).
Figure 3. AFM images of P3HT donor with different BnHCs, (a) 4-MeO-
BnHC, (b) 4-CO2Me-BnHC, (c) 3-CO2Me-BnHC, and (d) 2-MeO-4-CO2Me-
BnHC.
The surface morphologies of the BnHCs/P3HT active layer
images observed by atomic force microscopy (AFM) show that,
the surfaces of the active layers are homogeneous and display
nanoscale phase separation (Figure 3). The root mean squares
(RMS) were 5.25 nm for 4-MeO-BnHC, 0.63 nm for 4-CO2Me-
BnHC, 3.99 nm for 3-CO2Me-BnHC, and 0.54 nm for 2-MeO-4-
CO2Me-BnHC, respectively, when blended with P3HT donor.
Although the reason is not clear that PSCs based on 4-CO2Me-
BnHC and 3-CO2Me-BnHC showed the similar performances
despite their large difference roughness, it should be noted that 4-
CO2Me-BnHC has a lower solubility than 3-CO2Me-BnHC in
ODCB and chloroform. The RMSs indicate that the changing of
functional groups on benzyl moiety influences the roughness of
blend films. Moreover, the smoother surface based on 2-MeO-4-
CO2Me-BnHC/P3HT blend shows the highest photovoltaic
performance among the BnHCs films, implying that the better
interfacial contact of polymer donor and fullerene acceptor blend
is a key on the improvement of the PSC performances. The
morphology comprising of the dendrimer-bound G3-BnHC
displays the largest RMS of 21.7 nm (Figure S2e), resulting in
the lowest PCE due to the much lower Jsc.
4.2. Materials
Anhydrous 1,2-dichlorobenzene (Aldrich), toluene, carbon
disulfide, hexane, (WAKO), CoCl2, Mn (Aldrich), methyl 4-
(bromomethyl)-3-methoxybenzoate (TCL), single benzylic
bromide group at the focal point of the third-generation
dendrimer [G-3]-Br (Aldrich), [60]fullerene (Aldrich),
regioregular poly(3-hexylthiophene) (P3HT, Luminescence
Technology Corp.), PC61BM (Solenne), PEDOT:PSS
(CLEVIOS P VP Al 4083, H. C. Starck) were purchased and
used as received. The structures of BnHCs were determined by
using 1H NMR, 13C NMR, high resolution mass (HRMS).
4.3. Fabrication of PSC device and characterization
The PSC device was fabricated in the configuration
ITO/PEDOT:PSS/active layer/LiF/Al. The patterned ITO
(conductivity: 10ꢀ/square) glass was precleaned in an ultrasonic
bath of acetone and ethanol, and then treated in an ultraviolet-
ozone chamber. A thin layer (40 nm) of PEDOT:PSS was spin
coated on the ITO at 3000 rpm and subsequently dried at 110°C
for 10 min on a hot plate under air. The substrate was transferred
to an N2 glovebox and then dried again at 110°C for 10 min on a
hot plate. An ODCB solution of P3HT:PCBM (1:1, weight ratio,
210-260 nm) blend was subsequently spin coated onto the
PEDOT:PSS surface, forming an active layer. The thicknesses of
the blend films and PEDOT:PSS layers were measured using an
3. Conclusion
In conclusion, we have efficiently synthesized a series of
soluble electron acceptors BnHCs via Co-catalyzed highly
selective mono-functionalization of C60 with commercially
available functional benzyl bromides in one-step. Among the
BnHCs, PSC based on 2-MeO-4-CO2Me-BnHC as acceptor and

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automatic micro figure measuring instrument (Surfcorder ET200,
References and notes
Kosaka Laboratory Ltd.). The substrate with the active layer was
dried at 110°C for 10 min in the N2 glovebox. Finally, LiF (1 nm)
and Al (80 nm) were deposited onto the active layer by means of
conventional thermal evaporation at a chamber pressure lower
than 5×10-4 Pa, which provided the devices with an active area of
2×2 mm2. The current density–voltage (J–V) curves were
measured using an ADCMT 6244 DC Voltage Current
Source/Monitor under AM 1.5 solar-simulated light irradiation of
100 mW/cm2 (OTENTO-SUN III, Bunkoh-Keiki Co.). IPCE was
measured using a CEP-2000 system (Bunkoh-Keiki Co., Ltd.).
1. (a) Yu, G.; Gao, J.; Hummelen, J. C.; Wudl, F.; Heeger, A. J.
Science 1995, 270, 1789; (b) Waldauf, C.; Schilinsky, P.; Perisutti,
M.; Hauch, J.; Brabec, C. J. Adv. Mater. 2003, 15, 2084; (c)
Anthopoulos, T. D.; Tanase, C.; Setayesh, S.; Meijer, E. J.;
Hummelen, J. C.; Blom, P. W. M.; de Leeuw, D. M. Adv. Mater.
2004, 16, 2174.
2. (a) Li, C.-Z.; Yip, H.-L.; Jen, A. K.-Y. J. Mater. Chem. 2012, 22,
4161; (b) He, Y.; Li, Y. F. Phys. Chem. Chem. Phys. 2011, 13,
1970; (c) Matsuo, Y. Chem. Lett. 2012, 41, 754.
3. (a) Hummelen, J. C.; Knight, B. W.; LePeq, F.; Wudl, F. J. Org.
Chem. 1995, 60, 532-538; b) Kroon, J. M.; Verhees, W. J. H.;
Knol, J.; Hummelen, J. C.; van Hal, P. A.; Janssen, R. A. J.
Angew. Chem., Int. Ed. 2003, 42, 3371.
4.4. General procedure of Co-catalyzed hydroalkylation of C60
and benzyl bromides
4. (a) Lenes, M.; Wetzelaer, G. J. A. H.; Kooistra, F. B.; Veenstra, S.
C.; Hummelen, J. C.; Mlom, P. W. M. Adv. Mater. 2008, 20,
2116; (b) He, Y. J.; Chen, H. Y.; Hou, J. H.; Li, Y. F. J. Am.
Chem. Soc. 2010, 132, 1377; (c) Voroshazi, E.; Vasseur, K.;
Aernouts, T.; Heremans, P.; Baumann, A.; Deibel, C.; Xue, X.;
Herring, A. J.; Athans, A. J.; Lada, T. A.; Richter, H.; Rand, B. P.
J. Mater. Chem. 2011, 21, 17345; (d) Cheng, Y. J.; Liao, M. H.;
Chang, C. Y.; Kao, W. S.; Wu, C. E.; Hsu, C. S. Chem. Mater.,
2011, 23, 4056; (e) Li, C. Z.; Chien, S. C.; Yip, H. L.; Chueh, C.
C.; Chen, F. C.; Matsuo, Y.; Nakamura, E.; Jen, A. K. Y. Chem.
Commun. 2011, 47, 10082; (f) Zhang, C.; Chen, S.; Xiao, Z.; Zuo,
Q.; Ding, L. Org. Lett. 2012, 14, 1508; (g) Zhang,Y.; Matsuo, Y.;
Li, C.-Z.; Tanaka, H.; Nakamura, E. J. Am. Chem. Soc. 2011, 133,
8086; (h) Kim, B.; Yeom, H. R.; Choi, W. Y.; Kim, J. Y.; Yang, C.
Tetrahedron 2012, 68, 6696; (i) Kim, B.; Lee, J.; Seo, H. H.;
Wudl, F.; Park, S. H.; Yang, C. J. Mater. Chem. 2012, 22, 22958.
5. (a) Chen, H.-Y.; Hou, J.; Zhang, S.; Liang, Y.; Yang, G.; Yang,
Y.; Yu, L.; Wu, Y.; Li, G. Nat. Photonics 2009, 3, 649; (b) Liang,
Y.; Xu, Z.; Xia, J.; Tsai, S.-T.; Wu, Y.; Li, G.; Ray, C.; Yu, L.
Adv. Mater. 2010, 22, E135; (c) Chu, T.-Y.; Lu, J.; Beaupré, S.;
Zhang, Y.; Pouliot, J.-R.; Wakim, S.; Zhou, J.; Leclerc, M.; Li, Z.;
Ding, J.; Tao, Y. J. Am. Chem. Soc. 2011, 133, 4250; (d) Zhou,
H.; Yang, L.; Stuart, A. C.; Price, S. C.; Liu, S.; You, W. Angew.
Chem., Int. Ed. 2011, 50, 2995; (e) Price, S. C.; Stuart, A. C.;
Yang, L.; Zhou, H.; You, W. J. Am. Chem. Soc. 2011, 133, 4625;
(f) Son, H. J.; Wang, W.; Xu, T.; Liang, Y.; Wu, Y.; Li, G.; Yu, L.
J. Am. Chem. Soc. 2011, 133, 1885; (g) He, Z.; Zhong, C.; Huang,
X.; Wong, W.-Y.; Wu, H.; Chen, L.; Su, S.; Cao, Y. Adv. Mater.
2011, 23, 4636; (h) Huo, L.; Zhang, S.; Guo, X.; Xu, F.; Li, Y.;
Hou, J. Angew. Chem., Int. Ed. 2011, 50, 9697.
A suspension of CoCl2dppe (36.7 mg, 0.069 mmol), Mn (114
mg, 2.07 mmol), C60 (500 mg, 0.69 mmol), methyl 4-
(bromomethyl)-3-methoxybenzoate (536 mg, 2.07 mmol), and
H2O (124 ꢁL, 6.9 mmol) in ODCB (1,2-dichlorobenzene) (90
mL) was stirred for 48 h under Ar atmosphere at 25 oC. The
reaction mixture was monitored by TLC and HPLC analysis
(elution with toluene at 0.6 mL/min flow rate, detection at 320
nm). The mixture was filtered through a short florisil pad using
ODCB as an eluent. After concentration, the residue was purified
through silica gel chromatography using toluene as an eluent.
After evaporation of toluene, the residue was washed with
acetone and dried under vacuo, affording 2-MeO-4-CO2Me-
BnHC in 60% yield (373 mg).
4.5. Analytic data of 2-MeO-4-CO2Me-BnHC
1
Dark brown solid; H NMR (400 MHz, CDCl3/CS2 = 1/4) δ
3.94 (3H, s), 3.99 (3H, s),4.87 (2H, s), 6.69 (1H, s), 7.69 (1H, s),
7.76 (2H, s); 13C NMR (100 MHz, CDCl3/CS2 = 1/4) δ 46.43,
51.66, 55.09, 59.26, 65.24, 111.75, 121.94, 129.44, 130.82,
132.53, 135.06, 136.01, 139.46, 139.83, 141.16, 141.26, 141.48,
141.60, 141.63, 141.78, 142.18, 142.87, 144.18, 144.28, 144.93,
144.96, 145.07, 145.40, 145.68, 145.76, 145.80, 145.94, 146.00,
146.55, 146.87, 147.04, 153.33, 154.92, 157.55, 165.46; HRMS
(ESI) calcd for C70H12O3Na [M+Na]+: 923.06787, found
923.06789.
6. (a) Lu, S.; Jin, T.; Bao, M.; Yamamoto, Y. J. Am. Chem. Soc.
2011, 133, 12842; (b) Nambo, M.; Noyori, R.; Itami, K. J. Am.
Chem. Soc. 2007, 129, 8080; (c) Mori, S.; Nambo, M.; Chi, L.-C.;
Bouffard, J.; Itami, K. Org. Lett. 2008, 10, 4609; (d) Matsuo, Y.;
Iwashita, A.; Abe, Y.; Li, C.-Z.; Matsuo, K.; Hashiguchi, M.;
Nakamura, E. J. Am. Chem. Soc. 2008, 130, 15429.
Acknowledgments
This work was supported by World Premier International
Research Center Initiative (WPI), MEXT (Japan). S.L.
acknowledges the support of the JSPS fellowships for Young
Scientists. We also thank the support of the King Abdulaziz
University (KAU), under grant No. (HiCi/28-3-1432).
7. Lu, J.; Ding, J.; Alem, S.; Wakim, S.; Tse, S.-C.; Tao, Y.; Stupak,
J.; Li, J. J. Mater. Chem. 2011, 21, 4953.
8. (a) Brabec, C. J.; Cravino, A.; Meissner, D.; Sariciftci, N. S.;
Fromherz, T.; Rispens, M. T.; Sanchez, L.; Hummelen, J. C. Adv.
Funct. Mater. 2001, 11, 374; (b) Kooistra, F. B.; Knol, J.;
Kastenberg, F.; Popescu, L. M.; Verhees, W. J. H.; Kroon, J. M.;
Hummelen, J. C. Org. Lett. 2007, 9, 551.