Synthesis and fast electron-transfer reactions of fullerene-carbazole dendrimers with short linkages

Article abstract of DOI:10.1039/c3nj00770g

Fast electron-transfer reactions of newly synthesized (carbazole) _n dendrimers (n = 1, 3 and 7), which are connected with C ₆₀ with a short linkage, have been investigated in polar benzonitrile. The (carbazole)_n-C₆₀ dendrimers were characterized by spectroscopic, computational and electrochemical methods. The geometric and electronic structures of the C₆₀-(carbazole) _n dendrimers were examined by using the ab initio B3LYP/6-311G method. The distribution of the highest occupied frontier molecular orbital (HOMO) was found on the carbazole (Cz) entities, whereas the lowest unoccupied molecular orbital (LUMO) was located on the fullerene entity, suggesting the formation of the charge-separated (CS) states (C₆₀ ^--(carbazole)_n⁺). The redox measurements revealed that the charge separation from carbazole to the singlet-excited state of C₆₀ is thermodynamically feasible in polar benzonitrile. The femtosecond transient absorption measurements in the visible-NIR region revealed fast charge separation (～10¹¹ s^-1) from the carbazole to the singlet-excited state of C₆₀ producing the charge-separated states (C₆₀^--(carbazole)_n⁺) with lifetimes of 1.25-1.30 ns. The complementary nanosecond transient absorption measurements in the microsecond region revealed that the charge-separated states decayed to populate the triplet states of C₆₀, as well as the ground states. The higher charge separation/charge recombination ratios (～800) suggested the potential of compounds 1-3 to be light harvesting systems.

Full text of DOI:10.1039/c3nj00770g

View Article Online
View Journal
NJC
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: M. E. El-khouly, S. Lee, K. Kay and S.
Fukuzumi, New J. Chem., 2013, DOI: 10.1039/C3NJ00770G.
This is an Accepted Manuscript, which has been through the RSC Publishing peer
review process and has been accepted for publication.
Accepted Manuscripts are published online shortly after acceptance, which is prior
New Journal of Chemistry
An international journal of the chemical sciences
www.rsc.org/njc
Volume 34 | Number 12 | December 2010 | Pages 2685–3016
to technical editing, formatting and proof reading. This free service from RSC
Publishing allows authors to make their results available to the community, in
citable form, before publication of the edited article. This Accepted Manuscript will
be replaced by the edited and formatted Advance Article as soon as this is available.
To cite this manuscript please use its permanent Digital Object Identifier (DOI®),
which is identical for all formats of publication.
More information about Accepted Manuscripts can be found in the
Information for Authors.
Please note that technical editing may introduce minor changes to the text and/or
graphics contained in the manuscript submitted by the author(s) which may alter
content, and that the standard Terms & Conditions and the ethical guidelines
that apply to the journal are still applicable. In no event shall the RSC be held
responsible for any errors or omissions in these Accepted Manuscript manuscripts or
any consequences arising from the use of any information contained in them.
ISSN 1144-0546
PERSPECTIVE
Kaisa Helttunen and
Patrick Shahgaldian
Self-assembly of amphiphilic
calixarenes and resorcinarenes in water
1144-0546(2010)34:12;1-1
www.rsc.org/njc
Registered Charity Number 207890

Page 1 of 9
New Journal of Chemistry
View Article Online
DOI: 10.1039/C3NJ00770G
Synthesis and Fast Electron-Transfer Reactions of Fullerene-Carbazole
Dendrimers with Short Linkages
Mohamed E. El-Khouly,a* Sang-Ho Lee,b Kwang-Yol Kayb,* and Shunichi Fukuzumic,d,*
((Dedication, optional))
Fast electron-transfer reactions of newly synthesized
(carbazole)n dendrimers (n = 1, 3 and 7), which are connected
with C60 with a short linkage, have been investigated in polar
thermodynamically feasible in polar benzonitrile. The
femtosecond transient absorption measurements in the
visible-NIR region revealed fast charge separation (~ 1011 s-1)
benzonitrile.
characterized
The
by
(carbazole)n-C60
spectroscopic,
dendrimers
computational
were
and
from the carbazole to the singlet-excited state of C60
•+
producing the charge-separated states (C60•–-(carbazole)n
)
electrochemical methods. The geometric and electronic
structures of the C60-(carbazole)n dendrimers were examined
by using ab initio B3LYP/6-311G method. The distribution of
the highest occupied frontier molecular orbital (HOMO) was
found over the carbazole (Cz) entities, whereas the lowest
unoccupied molecular orbital (LUMO) was located over the
fullerene entity, suggesting the formation of the charge-
separated (CS) states (C60•–-(carbazole)n•+). The redox
measurements revealed that the charge separation from
carbazole to the singlet-excited state of C60 is
with lifetimes of 1.25~1.30 ns. The complementary
nanosecond transient absorption measurements in the
microsecond region revealed that the charge-separated states
decayed to populate the triplet states of C60, as well as the
ground states. The higher charge separation
/ charge
recombination ratios (~ 800) suggested the potential of
compounds 1-3 to be light harvesting systems.
Keywords: Fullerene . carbazole . electron transfer . laser
flash photolysis
special attention as a component of photoconductive poly-(N-
vinylcarbazole) (PVCz).17 Carbazoles have also been used as
Introduction
a
light-emitting photosensitizer, charge/hole transport
material in OLED applications, and photovoltaic and display
devices.17-21 Despite these unique properties and applications
of carbazole, there are only a few examples of electron
donor-acceptor systems using carbazole as an electron
donor, in which the charge separation is not so efficient.22
There are many examples of fast charge separation in
electron donor-acceptor systems using short linkage.23-28
However, there is no example of carbazole-linked C60 dyads
with short linkage.29
We report herein the synthesis, characterization and
electron-transfer reactions of fullerene (C60)-carbazole
dendrimers (Fig. 1), where C60-cored dendrimers are
connected with (carbazole)n dendrons (n = 1, 3 and 7) with
short linkages.30 Because of the short linkages between the
Cz and C60 units, an extremely fast charge separation
Photoinduced electron-transfer processes in donor-acceptor
systems have attracted considerable interest because of the
most critical aspects in photosynthesis and solar energy
conversion.1-6 In this line, great efforts have been done in the
last years from different research groups to prepare simple
donor-acceptor molecules (dyads, triads and tetrads).1-6
Recently, there is growing interest to prepare and
characterize novel donor-acceptor dendrimers that have
abilities to convert the sunlight to chemical energy.7-10
Dendrimers are known to be three-dimensional treelike
molecules processing well-defined structures composed of a
core and various numbers of dendrons.7-12
In the most of the successful donor-acceptor models, three
dimensional electron acceptors, fullerenes in general and C60
in particular, has be proven to be superior electron acceptors
due to their π-electron rich surface, favorable reduction
potentials and low reorganization energies in electron-
transfer reactions.6,13-16 Accordingly, in fullerene-containing
donor-acceptor systems, forward electron transfer occurs in
the top portion of the Marcus parabola while charge
recombination occurs in the inverted region of the parabola,
ultimately producing high charge separation/charge
recombination ratio.
aDepartment of Chemistry, Faculty of Science, Kafr ElSheikh
University, Kafr ElSheikh 33516, Egypt
Eꢀmail: mohamedelkhouly@yahoo.com
bDepartment of Material and Life Science, Graduate School of
Engineering, Osaka University, ALCA, Japan Science and Technology
Agency (JST), Suita, Osaka 565ꢀ0871, Japan
Eꢀmail: fukuzumi@chem.eng.osakaꢀu.ac.jp
cDepartment of Molecular Science and Technology, Ajou University,
Suwon 443ꢀ749, Korea. Eꢀmail: kykay@ajou.ac.kr
dDepartment of Bioinspired Science, Ewha Womans University, Seoul
120ꢀ750, Korea
Among various electron donors, carbazole, which is a
tricyclic molecule with two benzene rings fused on either side
of a five-membered nitrogen-containing ring, has attracted
1

New Journal of Chemistry
Page 2 of 9
View Article Online
DOI: 10.1039/C3NJ00770G
processes were achieved compared to the reported compounds were confirmed mainly by 1H NMR and elemental
1
dendrimers with long linkages.10 Such fast intramolecular analysis (see Experimental Section). H NMR spectra of 1, 2
charge separation processes from the carbazole to the and 3 are consistent with the proposed structures, showing
singlet-excited state of C60 were suggested from the steady- the expected features with the correct integration ratios,
state emission, and confirmed from the femtosecond respectively. The MALDI-TOF mass spectra provided a direct
transient absorption measurements. The energies of the evidence for the structures of 1, 2 and 3 showing a singly
charge-separated states were obtained from the cyclic charged molecular ion peaks at m/z = 1116.37 for 1, m/z =
voltammetry technique.
1446.52 for 2 and m/z = 2108.62 for 3 (Figs. S1-S3). Further
confirmation of 1, 2 and 3 was obtained from the steady-state
UV/vis measurements as shown in the forthcoming sections.
Fig. 1 Molecular structures of C60-(Cz)n 1-3.
Results and Discussion
The most straightforward preparation of compounds 1, 2 and
3 can be envisaged to proceed through a reaction sequence
of the following steps, i.e., the Ullmann31 and Prato’s 1, 3-
dipolar cycloaddition reactions32 as depicted in Scheme 1.
Every step of the reaction sequence proceeded smoothly and
efficiently to give a good or moderate yield of the product
(see Experimental Section for the synthetic details).
Commercially available carbazole was iodinated to give 5 in
68% yield and then the subsequent protection of amine
proton in 5 was carried out using p-toluenesulfonyl chloride
according to the literature procedure33 to give compound 6 in
73% yield. Compound 6 was reacted with carbazole under
Ullmann condition31 to produce compound 7 in 55.4% yield.
The tosyl group in 7 was then deprotected by base hydrolysis
to afford compound 8 in 90% yield. To increase the number
of carbazole units, Ullmann coupling reaction of compound 8
with compound 6 was repeated to produce 9 in 34% yield.
Deprotection of the tosyl group in 9 was then carried out
using base hydrolysis to obtain carbazole dendrimer 10 in
90% yield. Carbazole dendrons 4, 8 and 10 were reacted
with 4-iodobenzaldehyde under Ullmann conditions to give
monoaldehydes 11 (31%), 12 (34%) and 13 (66%),
respectively. Finally, aldehyde groups in 11, 12 and 13 were
reacted with N-octylglycine and C60 through Prato’s 1, 3-
dipolar cycloaddition32 to produce C60-cored carbazole
dendrimers 1 (30%), 2 (18%) and 3 (23%), respectively.
Scheme 1. Synthesis of compounds 1, 2 and 3. a) KI, KIO3, acetic
acid, reflux, 24 h, 68%. b) p-toluenesulfonyl chloride, NaH, DMF, 0I ,
4 h, 73%. c) 4, Cu2O, N,N-dimethylacetamide, reflux, 48 h, 55%. d)
(i) KOH, DMSO, H2O, reflux, 4 h, (ii) 6N HCl, 90%. e) 6, Cu2O, N,N-
dimethylacetamide, reflux, 48 h, 34%. f) 4-iodobenzaldehyde, Cu2O,
N,N-dimethylacetamide, reflux, 48 h, 66% for 11, 31% for 12, 33% for
13. g) C60, N-octylglycine, 1,2-dichlorobenzene, reflux, 24 h, 30% for
1, 18% for 2, 23% for 3.
C60–(carbazole)n dendrimers 1-3 and their precursor
compounds are very soluble in aromatic solvents (i.e.,
toluene, o-dichlorobenzene and benzonitrile) and other
common organic solvents (i.e., acetone, CH2Cl2, CHCl3 and
THF). The structures and purity of the newly synthesized
2

Page 3 of 9
New Journal of Chemistry
View Article Online
DOI: 10.1039/C3NJ00770G
Fig.
2
shows the steady-state absorption spectra of correspond to the singlet-excited state of C60 (1C60*). With
dendrimers 1-3 along with the reference compounds in increasing the time window from 5 to 40 ps, one can see
benzonitrile (PhCN). The spectral features of 1-3 in the visible clearly the decay of the 1C60* accompanied with the formation
range exhibited a strong absorption in the UV region and the of the characteristic absorption bands of C60 radical anion
characteristic absorption bands of fulleropyrrolidine (C60-ref) (C60•–) at 1000 nm6,13-16 and the Cz radical cation (Cz•+) at
at 698 and 432 nm. The absorption maxima of the carbazole 600 nm.34 This clear observation indicates the occurrence of
entities are located at 296 nm as a main band and shoulder electron transfer from Cz to the singlet-excited of C60
bands at 323 and 336 nm. The absorption bands in the UV affording the charge-separated state (C60•––Cz•+). The
•–
range (<400 nm) correspond to both fullerene and carbazole characteristic absorption band of C60 in the near-IR region
entities were also recorded. The absence of new absorption was employed as a reliable probe to determine the rate
bands in the visible-near IR region indicating no interaction constants of the charge separation (kCS
) and charge
between Cz and C60 moieties in the ground states of 1-3. recombination (kCR), because the fingerprint absorption band
•–
The photoinduced intramolecular events of 1-3 were of C60 band at 1000 nm does not overlap with the bands of
investigated by the steady-state fluorescence measurements other species.10,13-16 By fitting the rise time profile of C60 at
•–
in benzonitrile by using 430 nm excitation light, which excited 1000 nm (Fig. S4), the rate constant of charge separation
mainly the C60 entity. Fig.
2
shows extremely weak (kCS) was determined to be 4.64 × 1011 s-1. The short
fluorescence intensities of the singlet excited state of C60 distance between the centre of C60 and carbazole entities
(1C60*) at 710 nm of 1-3 compared to that of C60-ref (11.2 Å) may facilitate such fast electron-transfer process. By
suggesting that the emission of the C60* was heavily fitting the decay time profile of C60•–, the rate constant of
1
quenched by the appended carbazole entities because of the charge recombination (kCR) was found to be 7.99 × 108 s-1,
electron transfer from Cz to the singlet C60 (1C60*), by taking
into account that the energy transfer from C60* (1.75 eV) to
the singlet Cz (3.43 eV)20b is excluded due to the energetic
considerations.
from which the lifetime of charge-separated state (τCS) was
1
determined as 1.25 ns. By checking the absorption bands in
the visible and NIR (Fig. 2), one can see clearly that the
•–
decay of the C60 at 1000 nm is accompanied by the
formation of a new absorption band at 700 nm, which
corresponds to the triplet state of C60 (3C60*) with a rate
constant of 6.40 × 108 s-1. This finding may suggest that the
radical-ion pairs recombine to populate the triplet C60, as well
as the ground states.
Fig. 2 (Left) Steady-state absorption spectra of dendrimers 1-3 (1.0
x
10-4 M), along with C60-ref and Cz-ref in PhCN. (Right)
Fluorescence spectra of C60-(Cz)n and C60-ref in PhCN.
Concentrations are kept at 5.0 x 10-5 M;
λ
ex = 430 nm.
Femtosecond transient absorption spectroscopy was
employed to obtain further insight into the excited state
interactions in 1-3 to corroborate the proposed electron-
transfer process. Toward this end, compounds 1-3 were
probed with 390 nm laser light to selectively excite the C60
entity. Fig. 3 shows the transient spectral response for
representative 1. The spectral absorption features in the
Fig. 3 (Upper figure) Differential absorption spectra obtained upon
femtosecond flash photolysis (λex = 390 nm) of 1 (1.0 ×10-4 M) in
PhCN at the indicated time intervals. (Lower figures) Decay time
•–
3
visible region and NIR region, which are seen immediately profile of C60 (1000 nm) and rise time profile of C60* (700 nm),
(i.e., 5 ps) upon excitation of 1 in deaerated benzonitrile,
monitoring the charge recombination and formation of the triplet C60,
respectively.
3

New Journal of Chemistry
Page 4 of 9
View Article Online
DOI: 10.1039/C3NJ00770G
When turning to 2 and 3 (Figs. 4 and S5), the femtosecond
The charge-separation processes via 1C60* were
transient absorption spectra in benzonitrile showed similar supported from the viewpoint of thermodynamics of the
charge separation features as those of 1. By fitting the rise electron-transfer processes. The cyclic voltammograms of 1-
and the decay time profiles of C60•–, we determined the rates 3 in deaerated benzonitrile (Figs. 5 and S7-S9) showed the
of charge-recombination and lifetimes of the charge- first reduction potentials (Ered) of the C60 moiety at -570, -560
separated states as 7.87 × 108 s-1 and 1.27 ns (for 2) and and -555 mV vs. SCE for 1, 2 and 3, respectively. On the
7.69 × 108 s-1 and 1.30 ns (for 3).
other hand, the first oxidation potentials (Eox) of the Cz moiety
In dimethylformamide (DMF), similar spectral features were were located at 1020, 980 and 966 mV vs. SCE for 1, 2 and 3,
observed as those in benzonitrile (Fig. S6). By fitting the respectively, indicating that the oxidation potential of Cz entity
•–
decay time profiles of C60 at 1000 nm, we determined the is changed by increasing the Cz generation of the
rates of charge recombination as 2.00 × 109, 1.93 × 109 and dendrimer.35 Based on the first oxidation potential of the Cz
1.80 × 109 s-1 for 1, 2 and 3, respectively. From these values, moiety (Eox), the first reduction potential of the C60 moiety
the lifetimes of charge-separated states were determined as
(Ered), the coulombic term (Ec) and energy of the 1C60* (
ꢀ
E0-0),
GCR) and
ꢀGCS) were calculated according to
0.50, 0.52 and 0.55 ns for 1, 2 and 3, respectively. The
finding that the lifetimes of charge-separated-states of 1-3 in
the polar benzonitrile and dimethylformamide are not largely
dependent on the number of carbazole dendrons suggests
that the charge recombination between the closely spaced
the driving forces for charge recombination (ꢀ
ꢀ
charge separation (ꢀ
equations 1 and 2:36
ꢀ
ꢀ
ꢀ
GCR = e (Eox – Ered) + Ec
(1)
(2)
ꢀ
GCS E0-0 – (ꢀ GCR
=
ꢀ
ꢀ
)
•–
C60 and Cz•+ occurs in competition with the hole migration
From equations 1 and 2, the –ꢀGCR values were found to
be 1.65 eV (for 1), 1.60 eV (for 2) and 1.58 eV (for 3), by
taking into account that the coulombic term in polar solvents
is negligible (~0.06 eV).37 These values indicate that the
energy levels of the CS states of compounds 1-3 are lower
than the energy of the singlet C60 (1.75 eV) and higher than
the triplet C60 (1.55 eV).10-14 The negative
ꢀGCS values (-0.10
eV for 1, -0.15 eV for 2 and -0.17 eV for 3) suggest that the
electron transfer via the singlet excited state of C60 is
thermodynamically feasible in polar benzonitrile.
among the carbazole units. This behavior is different from our
previously reported SiPc-(C60)n dendrimers with long linkers
(where the τCS value increased with increasing the number of
C60 dendrons).10a This difference may be explained by the
short distance between the donor and acceptor (11 Å) of the
examined dendrimers 1-3 compared with the long distance
(25 Å) of the reported SiPc-(C60)n dendrimers.10a From this
comparison, it seems that the charge recombination in the
radical ion pairs occurs faster than the hole migration in 1-3,
while the hole migration seems to occur faster than charge
recombination in the reported SiPc-(C60)n dendrimers.10a
Fig. 5 Cyclic voltammogram of 1 (1.0 × 10-4 M) in deaerated PhCN
with TBAPF6 (0.1 M) as support electrolyte. Scan rate = 20 mV/s.
Moreover, the charge-separation process from Cz to C60
was supported by studying the molecular geometries and
electronic structures of 1-3 on the basis of molecular orbital
calculation using density functional method (DFT) at
B3LYP/6-311G level (Figs. 6, S10 and S11). The structures
were optimized to stationary point on the Born-Oppenheimer
potential surface. The centre-to-centre distance between C60
and the nitrogen atom of Cz entity of 1 was 11.2 Å. In
compounds 1-3, the orbital distribution of the highest
occupied molecular orbitals (HOMO and HOMO-1) was
located on the Cz entities, while the orbital distribution of
lowest unoccupied molecular orbital (LUMO) was located on
the C60 moiety. This suggests that upon excitation of the C60
unit, possible charge separation takes place first between the
electron-donating Cz and the C60 unit as an electron acceptor.
Fig. 4 (Upper figure) Differential absorption spectra obtained upon
femtosecond flash photolysis (λex = 390 nm) of 3 (1.0 × 10-4 M) in
PhCN at the indicated time intervals. (Lower figures) Rise and decay
time profiles of C60 at 1000 nm, monitoring charge-separation and
charge-recombination processes, respectively.
•–
4

Page 5 of 9
New Journal of Chemistry
View Article Online
DOI: 10.1039/C3NJ00770G
The absence of LUMOs on the Cz unit and HOMO on the C60
Fig. 8 summarized the intramolecular events for C60-(Cz)n
moiety proposes weak or no charge-transfer interactions dendrimers in PhCN. Upon excitation by the 390 nm laser
between the electron donor and acceptors in the ground state light, the C60 is excited to its singlet state (1C60*), which in
in compounds 1-3.
turn accept an electron from the electron-donating Cz to yield
•+
the charge-separated state C60•–-(Cz)n
.
The charge
LUMO
separated states, with their high energy levels, decayed to
populate the triplet states of C60, as well as the ground states.
1C60*-(Cz)n
Major processes
Minor processes
1.75 eV
kCS
•+
C60•– -(Cz)n
3C60*-(Cz)n
1.58 – 1.65 eV
kCR
1.55 eV
HOMO-1
HOMO
kCR
kT
hν
C60-(Cz)n
Fig.
8
Energy level diagram depicting the photoinduced
intramolecular events of C60-(Cz)n 1-3 in PhCN.
Fig. 6 The frontier HOMO, HOMO-1, and LUMO orbitals of 3
obtained by using ab initio B3LYP/6-311G method.
Conclusion
Photoexcitaion of newly synthesized (carbazole)n dendrimers
(n = 1, 3 and 7), which are connected with C60 with short
linkages, resulted in fast electron transfer from the carbazole
The complementary nanosecond transient absorption
measurements of 1-3 in PhCN with 430 nm laser excitation,
which selectively excites the C60 moiety, exhibited absorption
bands in the visible region with maxima at 700 nm, which
correspond to the triplet-excited state of C60 (3C60*) (Figs. 7,
•+
to the singlet-excited state of C60 generating C60•–-(Cz)n in
polar solvents. The electron-transfer process was suggested
from the steady-state emission, CV measurements and MO
calculations. The femtosecond laser photolysis confirmed the
occurrence of fast charge separation (~ 5.0 × 1011 s-1) in the
closely spaced 1-3, which is nearly 800 times faster than the
rates of charge recombination (~ 6.0 × 108 s-1). This finding
suggests the usefulness of the examined compounds 1-3 as
light harvesting systems. Unlike the donor-acceptor
dendrimers with long linkages,10 the τCS values observed for
the examined compounds are not largely dependent on the
number of carbazole dendrons. This may rationalized by the
3
S12 and S13).10,13-16 The decay rate constant of C60* was
determined to be 5.50 × 104 s-1. Such formation of the triplet
C60 may arise from the relaxation process of portion of the
singlet-excited state of C60 to its lower triplet state by
intersystem crossing process. The charge recombination
process of the radical-ion pair to populate the triplet state of
C60, as well as the ground state can be also considered in 1-3
from the following observations: (i) the rise of C60* (λmax = 700
nm) with the decay of the C60 radical anion (Figs. 2 and 3)
and (ii) the higher energy levels of the charge-separated
states (1.58-1.65 eV) compared with the 3C60* (1.55 eV).10-14
competition between the fast charge recombination between
•–
the closely spaced Cz•+ and C60
, and the charge
delocalization among the carbazole units. Another
explanation for this finding may arise from the larger solvent
reorganization energy of electron transfer due to an increase
in the distance between the plus and minus charges in
dendrimer 3. Such an increase in the solvent reorganization
energy of electron transfer is known to result in an increase in
the rate of back electron transfer in the Marcus inverted
region.28,38
Experimental Section
Materials and instruments
Reagents and solvents were purchased as reagent grade and used
without further purification. Compound 839 and N-octylglycine40 were
synthesized according to the published methods. All reactions were
performed using dry glassware under nitrogen atmosphere.
Fig. 7 Nanosecond transient absorption spectra of 3 (1.0 ×10-4 M)
obtained by 430 nm laser excitation light in deaerated PhCN. Inset:
Decay time profile of 3C60* at 700 nm.
5

New Journal of Chemistry
Page 6 of 9
View Article Online
DOI: 10.1039/C3NJ00770G
Analytical TLC was carried out on Merck 60 F254 silica gel plate and
3,6-Di(9H-carbazol-9-yl)-9-tosyl-9H-carbazole (7). To a solution
column chromatography was performed on Merck 60 silica gel (230- of 4 (2.92 g, 17.5 mmol) and 6 (5.0 g, 8.72 mmol) in N,N-
400 mesh). Melting points were determined on an Electrothemal IA dimethylacetamide (10 mL) was added copper oxide (2.50 g, 17.4
9000 series melting point apparatus, being uncorrected. NMR mmol). The mixture was refluxed for 48 hours, cooled to room
spectra were recorded on
a
Varian Mercury-400 (400 MHz)
temperature, and diluted with water. The precipitates were filtered,
spectrometer with TMS peak as reference. UV/Vis spectra were and recrystallized from dichloromethane/hexane (1:1) to produce 7
1
recorded on a Jasco V-550 spectrometer. MALDI-TOF MS spectra (3.15 g, 55.4%). H NMR (CDCl3, 400 MHz): δ = 2.40 (s, 3H), 7.20-
were recorded with an Applied Biosystems Voyager-DE-STR. 7.70 (m, 15H), 7.70 (d, 2H), 7.90 (d, 2H), 8.00 (d, 4H), 8.10 (d, 4H),
Elemental analyses were performed with a Perkin-Elmer 2400 8.59 (d, 2H). Anal. Calcd for C43H29N3O2S: C, 79.24%; H, 4.48%; N,
analyzer.
Steady-state fluorescence spectra were measured on a Shimadzu
RF-5300 PC spectrofluorophotometer equipped with
6.45%. Found: C, 79.11%; H, 4.59%; N, 6.37%.
a
3,6-Di(9H-carbazol-9-yl)-9H-carbazole (8). To a solution of
photomultiplier tube having high sensitivity in the 700–800 nm region. compound 7 (3.00 g, 4.60 mmol) in tetrahydrofuran (9 mL) were
Cyclic voltammograms were carried on
Voltammetric Analyzer. A platinum disk electrode was used as
a
BAS CV-50W
added dimethyl sulfoxide (4.5 mL) and water (1.5 mL), and the
mixture was stirred for 10 minutes. Subsequently, potassium
working electrode, while a platinum wire served as a counter hydroxide (1.50 g, 26.7 mmol) was added to this mixture, and the
electrode. SCE electrode was used as a reference electrode. All reaction mixture was refluxed for hours, cooled to room
measurements were carried out in o-dichlorobenzene containing temperature and diluted with water. After neutralization with dilute
tetra-n-butylammonium hexafluorophosphate (TBAPF6, 0.1 M) as the HCl solution (6 N), the crude product was filtered and recrystallized
4
supporting electrolyte. The scan rate was 20 mV/s.
from dichloromethane/hexane (1:1) to give 8 (2.07 g, 90%). Mp.
285 I . H NMR (CDCl3, 400 MHz): δ = 7.20-7.40 (m, 13H), 7.60 (d,
2H), 7.70 (d, 2H), 8.14 (d, 3H), 8.19 (s, 2H), 8.46 (s, 1H). Anal. Calcd
for C36H23N: C, 92.08%; H, 4.94%; N, 2.98%. Found: C, 92.25%; H,
1
Density-functional theory (DFT) calculations were performed on a
COMPAQ DS20E computer. The computational calculations were
performed by using the Becke3LYP functional and the 6-311G basis
set, with the restricted Hartree-Focck (RHF) formalism implemented 4.88%; N, 2.87%.
in the GAUSSIAN 03 program.41 The frontier HOMO and LUMO
were generated by using Gauss View software program (ver. 3.09)
developed by Semichem, Inc.
3,6-Di{3,6.di(9H-carbazol-9-yl)-9H-carbazol-9-yl}-9-tosyl-9H-
carbazole (9). To a solution of 6 (600 mg, 1.04 mmol) and 8 in N,N-
The studied compounds were excited by a Panther optical dimethylacetamide (10 mL) was added copper oxide (300 mg, 2.09
parametric oscillator (OPO) pumped by Nd:YAG laser (Continuum, mmol). The mixture was refluxed for 48 hours, cooled to room
temperature and diluted with water. The precipitates were filtered and
SLII-10, 4-6 ns fwhm) at
λ = 432 nm with the powers of 1.5 and 3.0
then recrystallized from dichloromethane/hexane (1:1) to give 9 (450
mJ per pulse. The transient absorption measurements were
performed using a continuous xenon lamp (150 W) and an InGaAs-
PIN photodiode (Hamamatsu 2949) as a probe light and a detector,
respectively. The output from the photodiodes and a photomultiplier
tube was recorded with a digitizing oscilloscope (Tektronix, TDS3032,
300 MHz). Femtosecond transient absorption spectroscopy
experiments were conducted using an ultrafast source: Integra-C
(Quantronix Corp.), an optical parametric amplifier: TOPAS (Light
Conversion Ltd.) and a commercially available optical detection
system: Helios provided by Ultrafast Systems LLC. The source for
the pump and probe pulses were derived from the fundamental
output of Integra-C (780 nm, 2 mJ/pulse and fwhm = 130 fs) at a
repetition rate of 1 kHz. 75% of the fundamental output of the laser
was introduced into TOPAS which has optical frequency mixers
resulting in tunable range from 285 nm to 1660 nm, while the rest of
the output was used for white light generation. Typically, 2500
excitation pulses were averaged for 5 seconds to obtain the transient
1
mg, 34%). H NMR (CDCl3, 400 MHz): δ = 7.20-7.40 (m, 25H), 7.60
(m, 10H), 7.92 (d, 2H), 8.00 (d, 2H), 8.12 (d, 8H), 8.28 (s, 3H), 8.32
(s, 2H), 8.76 (d, 2H). Anal. Calcd for C91H57N7O2S: C, 83.27%; H,
4.38%; N, 7.47%. Found: C, 83.12%; H, 4.46%; N, 7.39.
3,6-Di{3,6-di(9H-carbazol-9-yl)-9H-carbazol-9-yl}-9H-carbazole
(10). To a solution of 9 (350 mg, 0.266 mmol) in tetrahydrofuran (2
mL) were added dimethyl sulfoxide (0.9 ml), water (0.4 ml) and
potassium hydroxide (0.25 g, 44 mmol). The mixture was refluxed for
4 hours, cooled to room temperature, and neutralized with dilute HCl
(6 N). The crude product was filtered, and recrystallized from
dichloromethane/hexane (1:1) to afford 10 (280 mg, 90%). Mp. 293 I .
1H NMR (CDCl3, 400 MHz): δ = 7.20-7.30 (m, 8H), 7.30-7.40 (m,
16H), 7.58-7.62 (m, 10H), 8.82 (m, 3H), 8.14 (d, 8H), 8.28 (s, 3H),
8.44 (s, 2H), 8.62 (s, 1H). Anal. Calcd for C84H51N7: C, 87.10%; H,
4.44%; N, 8.46%. Found: C, 86.94%; H, 4.59%; N, 8.47%.
spectrum at
a set delay time. Kinetic traces at appropriate
4-(9H-carbazol-9-yl)benzaldehyde (11). To a solution of 4 (300
mg, 1.29 mmol) and 4-iodobenzaldehyde (220 mg, 1.31 mmol) in
N,N-dimethylacetamide (10 mL) was added copper oxide (370 mg,
2.58 mmol). The mixture was refluxed for 48 hours, cooled to room
temperature and diluted with water. The precipitates were filtered and
chromatographed on silica gel with dichloromethane/hexane (1:1) to
wavelengths were assembled from the time-resolved spectral data.
All measurements were conducted at 298 K. The transient spectra
were recorded using fresh solutions in each laser excitation.
Syntheses
1
afford 11 (230 mg, 66%) in a pale yellow solid. H NMR (CDCl3, 400
3,6-Diiodo-9H-carbazole (5). Carbazole (10.0 g, 59.8 mmol) was
dissolved in acetic acid (50 mL) and then warmed to 80I . To this
solution were added potassium iodide (13 g, 78.3 mmol) and
potassium iodate (10 g, 46.7 mmol). The mixture was refluxed for 24
hours and cooled to room temperature. The crude product was
diluted with water and filtered. The brown precipitates were stirred in
5% bisulfate solution for 2 hours and filtered. The product was
recrystallized from dichloromethane to give 5 (17.2 g, 68%) in a
brown solid. 1H NMR (CDCl3, 400 MHz): δ = 7.20 (d, 2H), 7.66 (d,
2H), 8.10 (s, 1H), 8.30 (s, 1H). Anal. Calcd for C12H7NI2: C, 34.39%;
H, 1.68%; N, 3.35%. Found: C, 34.48%; H, 1.77%; N, 3.28%.
MHz): δ = 6.30-6.35 (t, 2H), 7.40-7.52 (m, 4H), 7.75-7.82 (d, 2H),
8.08-8.21 (m, 4H), 10.10 (s, 1H). Anal. Calcd for C19H13NO: C,
84.11%; H, 4.83%; N, 5.16%. Found: C, 84.04%; H, 4.96%; N, 5.07%.
4-(9H-carbazol-9-yl)-1-(1-N-octyl-3,4-fulleropyrrolidin-2-
yl)]benzene (1). To a solution of 11 (25 mg, 0.092 mmol) and N-
octylglycine (35 mg, 0.186 mmol) in 1,2-dichlorobenzene (10 mL)
was added fullerene C60 (70 mg, 0.097 mmol). The mixture was
refluxed for 24 hours, and the solvent was evaporated under reduced
pressure. The crude product was chromatographed on silica gel with
toluene to remove unreacted fullerene, and then with
dichloromethane/carbon disulfide (40:1) to produce 1 (31 mg, 30%)
3,6-Diiodo-9-tosyl-9H-carbazole (6). To a solution of compound
5 (10.0 g, 23.8 mmol) in N,N-dimethylformamide (25 mL) was added
sodium hydride (2.40 g, 100 mmol) at 0I , and stirred 10 minutes.
Subsequently, p-toluenesulfonyl chloride (2.40 g, 100 mmol) was
added to this mixture and stirred at 0I for 4 hours. The mixture was
diluted with water and the precipitates were filtered. The crude
product was recrystallized from dichloromethane to afford 6 (10.1 g,
1
in a reddish black solid. Mp. 152 I . H NMR (CDCl3, 400 MHz): δ =
1.00 (m, 3H), 1.40 (m, 3H), 1.50 (m, 3H), 1.80 (m, 2H), 1.90-2.10 (m,
3H), 2.72 (m, 1H), 3.40 (m, 1H), 4.20 (d, 1H), 5.20 (d, 1H), 5.21 (s,
1H), 7.20-7.40 (m, 8H), 7.59-7.62 (d, 2H), 8.10 (d, 2H). Anal. Calcd
for C88H32N2: C, 94.60%; H, 2.89%; N, 2.51%. Found: C, 94.49%; H,
2.98%; N, 2.53%.
1
73%) in a brown solid. H NMR (CDCl3, 400 MHz): δ = 2.30 (s, 3H),
4-{3,6-Di(9H-carbazol-9-yl)-9H-carbazol-9-yl}benzaldehyde (12).
To a solution of 8 (150 mg, 0.301 mmol) and 4-iodobenzaldehyde (93
mg, 0.402 mmol) in N, N-dimethylacetamide (10 ml) was added
copper oxide (172 mg, 1.26 mmol). The mixture was refluxed for 48
7.10 (d, 2H), 7.60 (d, 2H), 7.79 (d, 2H), 8.05 (d, 2H), 8.16 (s, 2H).
Anal. Calcd for C19H13NO2SI2: C, 39.81%; H, 2.29%; N, 2.44%.
Found: C, 39.69%; H, 2.38%; N, 2.36%.
6

Page 7 of 9
New Journal of Chemistry
View Article Online
DOI: 10.1039/C3NJ00770G
hours, cooled to room temperature and diluted with water. The
precipitates were filtered and chromatographed on silica gel with
dichloromethane/hexane (2:1) to give 12 (57 mg, 31%) in a pale
yellow solid. 1H NMR (CDCl3, 400 MHz): δ = 7.12-7.20 (m, 4H), 7.25-
7.35 (m, 8H), 7.53-7.58 (m. 2H), 7.61-7.63 (d, 2H), 7.82-7.88 (d, 2H),
8.03-8.10 (d, 4H), 8.10-8.15 (d, 2H), 8.16-8.20 (s, 2H), 10.08 (s, 1H).
Anal. Calcd for C43H27N3O: C, 85.83%; H, 4.52%; N, 6.98%. Found:
C, 85.89%; H, 4.46%; N, 7.07%.
2
3
(a) D. Gust, T. A. Moore and A. L. Moore, Acc. Chem. Res.,
2009, 42, 1890; (b) M. R. Wasielewski, J. Org. Chem., 2006, 71,
5051.
(a) D. M. Guldi, Chem. Soc. Rev., 2002, 31, 22; (b) G. Bottari, G.
de la Torre, D. M. Guldi and T. Torres, Chem. Rev., 2010, 110,
6768; (c) D. M. Guldi, G. M. A. Rahman, V. Sgobba and C. Ehli,
Chem. Soc. Rev., 2006, 35, 471.
(a) D. Holten, D. F. Bocian and J. S. Lindsey, Acc. Chem. Res.,
2002, 35, 57; (b) L. Hammarstrm and S. Hammes-Schiffer, Acc.
Chem. Res., 2009, 42, 1859.
(a) F. D’Souza and O. Ito, Chem. Commun., 2009, 4913; (b) M.
E. El-Khouly, Y. Chen, X. Zhung and S. Fukuzumi, J. Am. Chem.
Soc., 2009, 131, 6370; (c) M. E. El-Khouly, J. B. Ryu, K.-Y. Kay,
O. Ito and S. Fukuzumi, J. Phys. Chem. C, 2009, 113, 15444;
(d) M. E. El-Khouly, A. N. Amin, M. E. Zandler, S. Fukuzumi and
F. D’Souza, Chem.ꢀEur. J., 2012, 18, 5239.
(a) S. Fukuzumi, Phys. Chem. Chem. Phys., 2008, 10, 2283-
2297; (b) S. Fukuzumi, T. Honda, K. Ohkubo and T. Kojima,
Dalton Trans., 2009, 3880; (c) S. Fukuzumi and K. Ohkubo, J.
Mater. Chem., 2012, 22, 4575; (d) M. E. El-Khouly, J. H. Kim, M.
Kwak, C. S. Choi, O. Ito and K.-Y. Kay, Bull. Chem. Soc. Jpn.
2007, 80, 2465.
(a) J.-F. Eckert, D. Byrne, J.-F. Nicoud, L. Oswald, J.-F.
Nierengarten, M. Numata, A. Ikeda, S. Shinkai and N. Armaroli,
New J. Chem., 2000, 24, 749; (b) D. I. Schuster, J. Rosenthal, S.
MacMahon, P. D. Jarowski, C. A. Alabi and D. M. Guldi, Chem.
Commun., 2002, 2538.
(a) K. Albrecht, Y. Kasai, Y. Kuramoto and K. Yamamoto, Chem.
Commun., 2013, 49, 865; (b) J.-F. Nierengarten, L. Oswald, F.-
F. Eckert, J.-F. Nicoud and N. Armaroli, Tetrahedron Lett., 1999,
40, 5681; (c) T. Nishioka, K. Tashiro, T. Aida, J.-Y. Zheng, K.
Kinbara, K. Saigo, S. Sakamoto and K. Yamaguchi,
Macromolecules, 2000, 33, 9182; (d) T. Kimura, T. Shiba, M.
Yamazaki, K. Hanabusa, H. Shirai and N. Kobayashi, J. Am.
Chem. Soc., 2011, 123, 5636.
(a) O. Usluer, S. Demic, D. A. M. Egbe, E. Brickner, C. Tozlu, A.
Pivrikas, A. M. Ramil and S. Sariciftci, Adv. Chem. Mater., 2010,
20, 4152; (b) J. You, G. Li and Z. Wang, Org. Biomol. Chem.,
2012, 10, 9481.
4
5
4-{3,6-Di(9H-carbazol-9-yl)-9H-carbazol-9-yl}-1-(1-N-octyl-3,4-
fulleropyrrolidin-2-yl)benzene (2). To a solution of 12 (30 mg,
0.049 mmol) and N-octylglycine (20 mg, 0.106 mmol) in 1,2-
dichlorobenzene (10 mL) was added fullerene C60 (50 mg, 0.074
mmol). The mixture was refluxed for 24 hours, and the solvent was
evaporated under reduced pressure. The crude product was
chromatographed on silica gel with toluene to remove unreacted
fullerene, and then with dichloromethane/carbon disulfide (40:1) to
6
1
give 2 (13 mg, 18%) in a reddish black solid. Mp. >350 I . (dec.). H
NMR (CDCl3, 400 MHz): δ =1.00 (m, 3H), 1.40 (m, 3H), 1.50 (m, 3H),
1.80 (m, 2H), 1.90-2.10 (m, 3H), 2.72 (m, 1H), 3.40 (m, 1H), 4.20 (d,
1H), 5.20 (d, 1H), 5.21 (s, 1H), 7.24-7.29 (m, 6H), 7.36-7.41 (m, 8H),
7.54-7.62 (m, 4H), 7.76-7.81 (d, 2H), 8.12-8.16 (d, 4H), 8.27 (s, 2H).
Anal. Calcd for C112H46N4: C, 92.93%; H, 3.20%; N, 3.87%. Found: C,
92.78%; H, 3.09%; N, 4.13%.
7
8
4-[3,6-Di{3,6-di(9H-carbazol-9-yl)-9H-carbazol-9-yl}-9H-
carbazol-9-yl]benzaldehyde (13). To a solution of 10 (200 mg,
0.173 mmol) and 4-iodobenzaldehyde (80 mg, 0.344 mmol) in N,N-
dimethylacetamide (10 mL) was added copper oxide (80 mg, 0.559
mmol). The mixture was refluxed for 48 hours, cooled to room
temperature and diluted with water. The precipitates were filtered and
chromatographed on silica gel with dichloromethane/hexane (2:1) to
give 12 (73 mg, 33.4%) in a pale yellow solid. Mp. 304 I . 1H NMR
(CDCl3, 400 MHz): δ = 7.20-7.30 (m, 10H), 7.30-7.40 (m, 14H), 7.55-
7.69 (m. 8H), 7.80-7.90 (s, 4H), 8.00-8.05 (d, 2H), 8.10-8.20 (d, 8H),
8.25-8.31 (s, 6H), 8.50-8.55 (s, 2H), 10.20 (s, 1H). Anal. Calcd for
C91H55NO: C, 92.75%; H, 4.70%; N, 1.19%. Found: C, 92.58%; H,
4.84%; N, 1.26%.
9
4-[3,6-Di{3,6-di(9H-carbazol-9-yl)-9H-carbazol-9-yl}-9H-
10 (a) M. E. El-Khouly, E. S. Kang, K.-Y. Kay, C. S. Choi, Y. Arakai
and O. Ito, Chem.ꢀEur. J., 2007, 13, 2854; (b) M. E. El-Khouly,
R. Anadakathir, O. Ito and L. Y. Chiang, J. Phys. Chem. A 2007,
111, 6938; (c) S. Fukuzumi, K. Saito, Y. Kashiwagi, M. J.
Crossley, S. Gadde, F. D’Souza, Y. Araki and O. Ito, Chem.
Commun., 2011, 47, 7980; (d) S. Fukuzumi, K. Ohkubo, K.
Saito, Y. Kashiwagi and M. J. Crossley, J. Porphyrins
Phthalocyanines, 2011, 15, 1292.
carbazol-9-yl]-1-(1-N-octyl-3,4-fulleropyrrolidin-2-yl)benzene (3).
To a solution of 13 (50 mg, 0.039 mmol) and N-octylglycine (15 mg,
0.08 mmol) in 1,2-dichlorobenzene (10 ml) was added fullerene C60
(30 mg, 0.041 mmol). The mixture was refluxed for 24 hours, and the
solvent was evaporated under reduced pressure. The crude product
was chromatographed on silica gel with toluene to remove unreacted
fullerene, and then with dichloromethane/carbon disulfide (1:1) to
give 3 (19 mg, 23%) in a reddish black solid. Mp. >350 I . (dec.) H 11 (a) Y. Rio, G. Accorsi, H. Nierengarten, J. L. Rehspringer, B.
1
NMR (CDCl3, 400 MHz): δ = 1.00 (m, 3H), 1.40 (m, 3H), 1.50 (m, 3H),
1.80 (m, 2H), 1.90-2.10 (m, 3H), 2.72 (m, 1H), 3.40 (m, 1H), 4.20 (d,
1H), 5.20 (d, 1H), 5.21 (s, 1H), 7.20-7.40 (m, 26H), 7.70-7.65 (m,
10H), 7.70-7.78 (m, 4H), 8.05 (d, 8H), 8.20 (s, 4H), 8.49 (s, 2H). Anal.
Calcd for C160H74N8: C, 91.15%; H, 3.54%; N, 5.32%. Found: C,
91.00%; H, 3.66%; N, 5.34%.
Hoenerlarge, G. Kppitkovas, A. Ghugreev, A. Van Dorsselaer, N.
Armaroli and J.-F. Nierengarten, New. J. Chem., 2002, 26,
1146; (b) J.-F. Nierengarten, N. Armaroli, G. Accorsi, Y. Rio and
J.-F. Eckert, Chem.ꢀEur. J., 2003, 9, 36; (c) N. Armaroli, G.
Accorsi, J. N. Clifford, J.-F. Eckert and J.-F. Nierengarten,
Chem. Asian. J., 2006, 1, 564.
12 (a) K. Hosomizu, H. Imahori, U. Hahn, J.-F. Nierengarten, A.
Listorti, N. Armaroli, T. Nemoto and S. Isoda, J. Phys. Chem. C,
2007, 111, 2777; (b) A. Gegout, J. L. Delgado, J.-F.
Nierengarten, B. Delavaux-Nicot, A. Listorti, C. Chiroboli, A.
Belbakra and N. Armaroli, New. J. Chem., 2009, 33, 2174; (c) U.
Hahn, J.-F. Nierengarten, B. Delavaux-Nicot, F. Monti, C.
Chiorboli and N. Armaroli, New. J. Chem., 2011, 35, 2234.
13 Fullerenes: From Synthesis to Optoelectronic Properties; D. M.
Guldi and N. Martin, (Eds.), Kluwer Academic Publishers:
Dordrecht, 2002.
Supporting Information
MALDI-TOF mass spectra of compound 1-3, MO calculations of
compounds 1 and 2, femtosecond transient spectra of compound 2,
CV and DPV for compound 2 and 3, Optimized structures of 1 and 2,
and nanosecond transient spectra of compounds
deaerated benzonitrile.
1 and 2 in
Acknowledgments
14 (a) S. Fukuzumi, K. Ohkubo, H. Imahori, J. Shao, Z. Ou, G.
Zheng, Y. Chen, R. K. Pandey, M. Fujitsuka, O. Ito and K. M.
Kadish, J. Am. Chem. Soc., 2001, 123, 10676; (b) H. Imahori, D.
M. Guldi, K. Tamaki, Y. Yoshida, C. Luo, Y. Sakata and S.
Fukuzumi, J. Am. Chem. Soc., 2001, 123, 6617; (c) H. Imahori,
Y. Sekiguchi, Y. Kashiwagi, T. Sato, Y. Araki, O. Ito, H. Yamada
and S. Fukuzumi, Chem.ꢀEur. J., 2004, 10, 3184; (d) F. D’Souza,
E. Maligaspe, K. Ohkubo, M. E. Zandler, N. K. Subbaiyan and S.
Fukuzumi, J. Am. Chem. Soc., 2009, 131, 8787.
15 (a) M. E. El-Khouly, O. Ito, P. M. Smith and F. D’Souza, J.
Photochem. Photobiol. C, 2004, 5, 79; (b) M. E. El-Khouly, S. H.
Shin, Y. Araki, O. Ito and K.-Y. Kay, J. Phys. Chem. B, 2008,
112, 3910; (c) M. E. El-Khouly, L. M. Rogers, M. E. Zandler, G.
This work was supported by Grants-in-Aid (Nos. 20108010) from the
Ministry of Education, Culture, Sports, Science and Technology,
Japan and NRF/MEST of Korea through the WCU (R31-2008-000-
10010-0) and GRL (2010-00353) Programs.
References
1
(a) Anoxygenic Photosynthetic Bacteria; R. E. Blankenship, M. T.
Madigan and C. E. Bauer (Eds.), Kluwer Academic Publisher:
Dordecht, 1995; (b) R. A. Wheeler, In Introduction to the
Molecular Bioenergetics of Electron, Proton, and Energy
Transfer; ACS Symposium Ser, 2004, Vol. 883, 1–6.
7

New Journal of Chemistry
Page 8 of 9
View Article Online
DOI: 10.1039/C3NJ00770G
Suresh, M. Fujitsuka, O. Ito and F. D’Souza, ChemPhysChem, 34 J. F. Ambrose, L. L. Carpenter and R. F. Nelson, J. Electrochem.
2003, 4, 474. Soc., 1975, 876.
16 (a) M. E. El-Khouly, D. K. Ju, K.-Y. Kay, F. D’Souza and S. 35 (a) F. Loiseau, S. Campagna, A. Hameurlain and W. Dehaen, J.
Fukuzumi, Chem.ꢀEur. J., 2010, 16, 6193; (b) M. E. El-Khouly,
C. A. Wijesinghe, N. V. Nesterov, M. V. Zandler, S. Fukuzumi
and F. D’Souza, ChemꢀEur. J., 2012, 18, 13844; (c) M. E. El-
Am. Chem. Soc., 2005, 127, 11352; (b) K. Albrecht and K.
Yamamoto, J. Am. Chem. Soc., 2009, 131, 2244; (c) J. li, T.
Zhang, Y. Liang and R. Yang, Adv. Funct. Mater., 2013, 23, 619.
Khouly, P. Padmawar, Y. Araki, S. Verma, L. Y. Chiang and O. 36 N. Matga and H. Miyasaka, In Electron Transfer, J. Jortner, M.
Ito, J. Phys. Chem. A 2006, 110, 884.
17 (a) Y. Wang, Nature, 1992, 356, 585; (b) Y. Wang and A. Suna,
J. Phys. Chem. B, 1997, 101, 5627.
Bixon, (Eds.), John Wiley & Sons: New York, 1999, part 2, pp.
431-496.
37 Fundamentals of Photoinduced Electron Transfer; G. J.
18 (a) C. W. Tang and S. A. VanSlyke, Appl. Phys. Lett., 1987, 51,
Kavarnos (Ed.), VCH Publishers Ltd. UK, 1993.
913; (b) A. C. Grimsdale, K. L. Chan, R. E. Martin, P. G. Jokisz 38 R. A. Marcus and N. Sutin, Biochim. Biophys. Acta, 1985, 811,
and A. B. Holmes, Chem. Rev., 2009, 109, 897; (c) J. He, H. Liu,
265.
Y. Dai, X. Ou, J. Wang, S. Tao, X. Zhang, P. Wang and D. Ma, 39 Z. Zhao, Y. Xing, Z. Wang and P. Lu, Org. Lett., 2007, 9, 547.
J. Phys. Chem. C, 2009, 113, 6761.
19 (a) C. H. Tao, N. Zhu and V. W. Yam, J. Photochem. Photobiol.
A, 2009, 207, 94; (b) S. Lamansky, R. C. Kwong, M. Nugent, P.
40 (a) C. M. Dever and P. D. Adawadkar, Biopolymers, 1979, 18,
2375; (b) M. E. El-Khouly, S. H. Shim, Y. Araki, O. Ito and K.-Y.
Kay, J. Phys. Chem. B, 2008, 112, 3910.
I. Djurovich and M. E. Thompson, Org. Electron., 2001, 2, 53; 41 Gaussian 03, Gaussian, Inc., Pittsburgh PA, 2003.
(c) Y. Deng, Y. Chen, X. Zhang, H. Tian, C. Bao, D. Yan, Y.
Geng and F. Wang, Macromolecules, 2012, 45, 8621.
20 A. Ryan, B. Tuffy, S. Horn, W. J. Blau and M. O. Senge,
Tetrahedron, 2011, 67, 8248.
21 (a) M.-D. Zhang, H.-X. Xie, X.-H. Ju, L. Qin, Q.-X. Yang, H.- G.
Zheng and X.-F. Zhou, Phys. Chem. Chem. Phys., 2013, 15,
634; (b) T. M. Clarke, J. Peet, A. Nattestad, N. Drolet, G.
Dennler, C. Lungenschmied, M. Leclerc and A. Mozer, J. Org.
Electron., 2012, 13, 2639; (c) H. U. Kim, D. Mi, J.-H. Kim, J. B.
Park, S. C. Yoon, U. C. Yoon and D.-H. Hwang, Sol. Energ. Mat.
Sol. Cells, 2012, 105, 6.
22 (a) T. Konno, M. E. El-Khouly, Y. Nakamura, K. Kinoshita, Y.
Araki, O. Ito, T. Yoshihara, S. Tobita and J. Nishimura, J. Phys.
Chem. C, 2008, 112, 1244; (b) C. K. C. Bikram, N. K. Subbaiyan
and F. D’Souza, J. Phys. Chem. C, 2012, 116, 11964; (c) A.
Baschieri, L. Sambri, I. Gualandi, D. Tonelli, F. Monti, A. D.
Esposti and N. Armaroli, RSC Adv., 2013, 3, 6507.
23 (a) S. Fukuzumi, H. Kotani, K. Ohkubo, S. Ogo, N. V.
Tkachenko and H. Lemmetyinen, J. Am. Chem. Soc., 2004, 126,
1600; (b) M. Murakami, K. Ohkubo and S. Fukuzumi, Chem.–
Eur. J., 2010, 16, 7820; (c) M. Murakami, K. Ohkubo, T. Nanjo,
K. Souma, N. Suzuki and S. Fukuzumi, ChemPhysChem, 2010,
11, 2594; (d) H. Kotani, K. Ohkubo and S. Fukuzumi, Faraday
Discuss., 2012, 155, 89.
24 (a) K. Ohkubo, H. Kotani, J. Shao, Z. Ou, K. M. Kadish, G. Li, R.
K. Pandey, M. Fujitsuka, O. Ito, H. Imahori and S. Fukuzumi,
Angew. Chem., Int. Ed., 2004, 43, 853; (b) N. V. Tkachenko, H.
Lemmetyinen, J. Sonoda, K. Ohkubo, T. Sato, H. Imahori and S.
Fukuzumi, J. Phys. Chem. A, 2003, 107, 8834.
25 D. Curiel, K. Ohkubo, J. R. Reimers, S. Fukuzumi and M. J.
Crossley, Phys. Chem. Chem. Phys., 2007, 9, 5260.
26 (a) C. Romero-Nieto, J. Guilleme, J. Fernández-Ariza, M. S.
Rodríguez-Morgade, D. González-Rodríguez, T. Torres and D.
M. Guldi, Org. Lett., 2012, 14, 5656; (b) M. E. El-Khouly, J. B.
Ryu, K.-Y. Kay, O. Ito and S. Fukuzumi, J. Phys. Chem. C, 2009,
113, 15444.
27 P. V. Solntsev, K. L. Spurgin, J. R. Sabin, A. A. Heikal and N. V.
Nemykin, Inorg. Chem., 2012, 51, 6537.
28 K. Ohkubo, H. Imahori, J. Shao, Z. Ou, K. M. Kadish, Y. Chen,
G. Zheng, R. K. Pandey, M. Fujitsuka, O. Ito and S. Fukuzumi, J.
Phys. Chem. A, 2002, 106, 10991.
29 For intermolecular photoinduced electron-transfer reactions, see:
(a) A. Watanabe and O. Ito, J. Chem. Soc., Chem. Commun.,
1994, 1285; (b) G. Sauve, N. M. Dimitrijevic and P. V. Kamat, J.
Phys. Chem., 1995, 99, 1199; (c) A. Itaya, I. Suzuki, Y. Tsuboi
and H. Miyasaka, J. Phys. Chem. B, 1997, 101, 5118; (d) T.
Midorikawa, Y. Araki, M. Fujitsuka and O. Ito, J. Nanosci.
Nanotechnol., 2007, 7, 1419.
30 For carbazole dendrimer, see: (a) K. Albrecht, Y. Kasai, Y.
Kuramoto and K. Yamamoto, Chem. Commun., 2013, 49, 865;
(b) K. Albrecht, R. Pernites, M. J. Felipe, R. C. Advincula and K.
Yamamoto, Macromolecules, 2012, 45, 1288; (c) K. Albrecht
and K. Yamamoto, J. Am. Chem. Soc., 2009, 131, 2244.
31 (a) F. Ullmann and J. Bierlecki, Ber. Dtsch. Chem. Ges., 1901,
34, 2174; (b) S. Gauthier and J. M. J. Frechet, Synthesis, 1987,
383.
32 M. Maggini, G. Scorrano and M. Prato, J. Am. Chem. Soc.,
1993, 115, 9798.
33 T. Xu, R. Lu, M. Jin, X. Qiu, P. Xue, C. Bao and C. Zhao,
Tetrahedron Lett., 2005, 46, 6883.
8

Page 9 of 9
New Journal of Chemistry
View Article Online
DOI: 10.1039/C3NJ00770G
Table of Contents
Synthesis and Fast Electron-Transfer Reactions of Fullerene-Carbazol
Dendrimers with Short Linkers
Mohamed E. El-Khouly,* Sang-Ho Lee, Kwang- Yol Kay,* and Shunichi
Fukuzumi*
Fast and efficient electron-transfer reactions of the closely spaced C60-
(carbazole)n dendrimers (n = 1, 3 and 7) were observed by the femtosecond and
nanosecond laser photolysis techniques.