Th-symmetrical hexakisadducts of C60 with a densely packed π-donor shell can act as energy- or electron-transducing systems

Article abstract of DOI:10.1002/1521-3765(20020215)8:4<979::AID-CHEM979>3.0.CO;2-6

For the first time several T_h-symmetrical hexakisadducts of C₆₀ bearing up to six electro- and photoactive o-phenylene diamine or 9,10-dialkoxyanthracene moieties were synthesized and subjected to photoinduced electron/energy-transfer studies. Both donors form a densely packed π-donor shell surrounding the fullerene core. In these novel core-shell ensembles (7 and 19), either an efficient energy transfer from the dialkoxyanthracene periphery, or an electron transfer from the o-phenylene diamine periphery transduces the flow of excited-state energy or electrons, respectively, to the fullerene moiety, which resides in the central core. Due to the relatively high reduction potential of the fullerene core, which is anodically shifted by ≈0.7 V, compared with that of pristine C₆₀, the outcome of these intramolecular reactions depends mainly on the donor ability of the peripheral system. Interestingly, the charge-separated state in the o-phenylene diamine heptad (7; τ = 2380 ns in benzonitrile) is stabilized by a factor of 20 relative to the corresponding o-phenylene diamine dyad (6; τ = 120 ns in benzonitrile), an effect that points unequivocally to the optimized storage of charges in this highly functionalized fullerene ensemble.

Full text of DOI:10.1002/1521-3765(20020215)8:4<979::AID-CHEM979>3.0.CO;2-6

FULL PAPER
T -Symmetrical Hexakisadducts of C with a Densely Packed p-Donor Shell
h
60
Can Act as Energy- or Electron-Transducing Systems
[
b]
[a]
[a]
[b]
Michael Diekers, Chuping Luo, Dirk M. Guldi,* and Andreas Hirsch*
Dedicated to Professor Ortwin Brede on the occasion of his 60th birthday
Abstract: For the first time several Th-
symmetrical hexakisadducts of C60 bear-
ing up to six electro- and photoactive o-
phenylene diamine or 9,10-dialkoxyan-
thracene moieties were synthesized and
subjected to photoinduced electron/en-
ergy-transfer studies. Both donors form
a densely packed p-donor shell sur-
rounding the fullerene core. In these
novel core ± shell ensembles (7 and 19),
either an efficient energy transfer from
the dialkoxyanthracene periphery, or an
electron transfer from the o-phenylene
diamine periphery transduces the flow
of excited-state energy or electrons,
respectively, to the fullerene moiety,
which resides in the central core. Due
to the relatively high reduction potential
of the fullerene core, which is anodically
shifted by ꢀ0.7 V, compared with that of
pristine C , the outcome of these intra-
molecular reactions depends mainly on
the donor ability of the peripheral
system. Interestingly, the charge-sepa-
rated state in the o-phenylene diamine
heptad (7; t ˆ 2380 ns in benzonitrile) is
stabilized by a factor of 20 relative to the
corresponding o-phenylene diamine dy-
ad (6; t ˆ 120 ns in benzonitrile), an
effect that points unequivocally to the
optimized storage of charges in this
highly functionalized fullerene ensem-
ble.
6
0
Keywords: donor± acceptor systems
electron transfer ¥ fullerenes ¥
nanostructures
¥
Introduction
has never been accomplished so far in an artificial photo-
synthetic reaction center.
Ever since the discovery of C , its aesthetically pleasing
Consequently, the utilization of C -based materials in
6
0
60
structure with perfect icosahedral symmetry, has held a deep
fascination for chemists who construct architectures of higher
complexity (i.e., core ± shell structures, dendrimers, etc.).[
Furthermore, the electron- and energy-acceptor properties
of fullerenes stimulated a remarkable growth, which has led to
a seemingly disparate field of studies. The delocalization of
charges–electrons or holes–within the giant, spherical
carbon framework (diameter >7.5 ä) together with the rigid,
confined structure of the aromatic p-sphere offer unique
opportunities for stabilizing charged entities.[ An impressive
demonstration of this is the 24% efficient charge separation
nanostructured devices, such as photoelectrochemical cells,
that gives rise to efficient photocurrent generation, is
currently at the forefront of intense investigation. As far
1]
[4]
as injection of electrons into semiconducting electrodes is
concerned, however, certain limitations of choosing this
acceptor emerge. One of the biggest shortcomings is the low
first one-electron reduction potential (ꢀ À 0.9 V versus
ferrocene) which, although rendering them good electron
acceptors, limits the energy for injection into the electrode in
2]
[5]
molecular devices. Ultimately, this limits the energy stored
in the charge-separated state.
In the search for fullerene structures that enable us to
address these issues (vide supra), we now report on the design
[3]
within a C -based molecular tetrad. The lifetime of the
60
spatially separated (ꢀ49 ä) radical pair, a product of a
sequence of energy- and electron-transfer reactions, reaches
well beyond milliseconds (0.38 s) into a time domain which
of two novel T -hexakisadducts (7 and 19). The highly
h
symmetric T -tecton facilitates loading of the fullerene core
h
with a shell of up to six electron-donor moieties, which makes
these systems particularly appealing for photoconversion
processes. Although considerable attention has focused on
the hexa-addition of fullerenes,[ addition of electron donors
and/or chromophores and, thereby, the design of highly
functional donor± acceptor model systems is rare so far.
Placing six chromophores at the fullerene periphery enhances,
for example, the light-collection and light-transduction fea-
tures of the resulting core ± shell ensembles. Ultimately this
can lead to high solar energy conversion efficiencies, com-
parable with those seen in dendrimer structures.
[
a] Dr. habil. D. M. Guldi, Dr. C. Luo
University of Notre Dame, Radiation Laboratory
Notre Dame, IN 46556 (USA)
Fax : (‡1)219-631-8068
1, 6]
E-mail: guldi.1@nd.edu
[
b] Prof. Dr. A. Hirsch, Dipl.-Chem. M. Diekers
Institut f¸r Organische Chemie
Universit‰t Erlangen-N¸rnberg
Henkestr. 42, 91054 Erlangen (Germany)
Fax : (‡49)9131-8522537
E-mail: hirsch@organik.uni-erlangen.de
Chem. Eur. J. 2002, 8, No. 4
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D. M. Guldi, A. Hirsch et al.
FULL PAPER
3-Dimensional core ± shell architectures are typically de-
signed to bear an electro- and/or photoactive interior core, a
sterically crowded, closed-packed shell, and a highly func-
tional surface. Some of their most fascinating features extend
to light-harvesting arrays and electron-transfer relays of
different complexities (i.e., enhancing the molecular function
with increasing generation).[
7]
For the present study, o-phenylene diamine (E1/2
0.232 V versus ferrocene) and 9,10-dialkoxyanthracene
ˆ
‡
(
E
ˆ ‡0.620 V versus ferrocene) were chosen as electron-
1/2
[8]
donating addends, since the difference in their one-electron
oxidation potentials helps to modulate the free energy
o
changes, ÀDG . Both o-phenylene diamine and 9,10-di-
ET
alkoxyanthracene create shells of densely packed p-donors
surrounding the fullerene core, and thereby shield it quite well
from the environment. In this paper, a detailed account of the
photophysical properties is given, with particular focus on the
electron- and energy-transduction processes.
Results and Discussion
Syntheses: The design of a hexakisadduct containing six o-
phenylenediamine addends is based on the fact that a sixfold
addition of malonates by using the template mediation
technique that we developed previously leads to adducts with
a pseudo-octahedral T -symmetrical addition pattern with
h
good yields and regioselectivities.[ This approach requires
the symmetrical incorporation of the o-phenylenediamine
moiety into a cyclic malonate, since otherwise the overall
symmetry of the resulting hexakisadduct would be lower than
9]
T , and a mixture of constitutional isomers would be obtained
h
that would be difficult to separate. We therefore selected the
cyclic malonate 1 as a suitable target addend, which was
obtained by transformation of the dimethyl-o-phenylenedi-
Scheme 1. Formation of cyclic malonate 1 by transformation of the
dimethyl-o-phenylenediamine 2 into the diol 3 followed by coupling with
malonyl dichloride.
amine 2[ into the diol 3
10]
[11]
and subsequent coupling with
malonyl dichloride (Scheme 1). The last step was carried out
using very dilute solutions of the starting materials in order to
prevent polymerization. For this purpose, a solution of
malonyl dichloride in methylene chloride (8 mm) was slowly
added (30 drops per min) to 3 (4 mm) in methylene chloride.
In addition to the [1‡1] macrocycle 1 the [2‡2] and [3‡3]
rings 4 and 5 were formed simultaneously. The three cyclic
malonates 1, 4, and 5 were formed in a 10:8:1 ratio with an
overall yield of 30%. After isolation by preparative HPLC all
three macrocycles were completely characterized. As expect-
ed, the NMR spectra of 1, 4, and 5 are qualitatively the same,
since the cyclic oligomers contain the same number of
magnetically inequivalent sets of H and C atoms.
odology (Scheme 3). For this purpose, C60 was treated with a
tenfold excess of malonate 1 in the presence of 9,10-dimethyl-
anthracene (DMA) and CBr /DBU. Isolation of 7 was
4
accomplished by flash chromatography followed by prepara-
tive HPLC. Compound 7 has the typical spectroscopic fea-
To test whether the monomalonate 1 was suitable for
nucleophilic cyclopropanations, we first synthesized the
monoadduct 6 by allowing 1 to react with C60 in the presence
of CBr and DBU (diazabicycloundecane, Scheme 2). After
4
purification by flash chromatography using a mixture of
toluene and triethylamine as eluent, 6 was obtained in 23%
yield. The spectroscopic characterization of monoadduct 6 is
consistent with the depicted structure.
Subsequently, hexakisadduct 7 was synthesized in 12%
isolated yield using the reversible template mediation meth-
Scheme 2. Synthesis of the monoadduct 6 by the reaction of 1 with C60 in
the presence of CBr and DBU.
4
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Chem. Eur. J. 2002, 8, No. 4

T -Symmetrical Hexakisadducts of C
h
979±991
60
Scheme 3. Synthesis of hexakisadduct 7 by using the reversible template
mediation methodology.
tures commonly observed for T -symmetrical hexakisadducts.
h
1
3
For example, in the C NMR spectrum only two signals
2
3
Scheme 4. Formation of diol 8 and compounds 9 and 10.
appear for the sp - and one signal for the sp -C atoms of the
fullerene cage at d ˆ 140.9, 145.7, and 69.0, respectively. The
FAB mass spectrum displays the molecular ion peak at m/z ˆ
2630, and the UV/Vis spectrum of the yellow compound 7
The bifunctional donor 11 should be a suitable addend for a
shows the typical structure, with the most intensive absorp-
tions at lmax ˆ 239 and 270 nm.
tether functionalization of C . The corresponding cyclopro-
6
0
panation reaction afforded a mixture of the monoadduct 12,
the bisadducts 13 ± 15, and the dimer 16 in yields of 23%, 5%,
9%, 3%, and 3%, respectively (Scheme 5). The purification
of 12 was achieved by flash chromatography. The bisadducts
and the dimer were subsequently isolated by preparative
HPLC. Whereas the characterization of the monoadduct 12
and the dimer 16 was straightforward, the structure assign-
ment of the bisadducts 13 ± 15 required careful evaluation of
the spectroscopic and computational data and comparison of
In order to synthesize new donor± acceptor systems, we
decided to use the anthracene moiety, which is more difficult
to oxidize than the o-phenylene diamine unit. As starting
material we used anthraquinone, which was reduced, and
subsequently hydroxyalkylated to give the diol 8 (Scheme 4).
In analogy to diol 3, which we have also previously trans-
formed into a bismalonate by allowing it to react with methyl
malonyl chloride,[ we used 8 to synthesize both the cyclic
12]
monomalonate 9 and the open chain bismalonate 11
their electronic absorption spectra with those reported for
Scheme 4).[
13]
As in the o-phenylenediamine case, the
related regioisomeric bisadducts.
[1a, 14]
In principle, over and
(
formation of the [1‡1] macrocycle 9 is accompanied by that
of the [2‡2] ring 10, even though the reaction was carried out
under high dilution conditions. Compounds 9 and 10 were
formed in a 3:2 ratio in an overall yield of 23%. Isolation was
achieved by flash chromatography using a toluene/ethyl
acetate mixture as eluent.
above to the seven bisaddition patterns (cis-2, cis-3, e, trans-4,
trans-3, trans-2, trans-1) that can be achieved by two malonate
addends, ™in ± out∫ geometrical isomers of the resulting
cyclopropane rings also have to be considered. However,
due to steric restrictions only out ± out isomers are possible.
As a consequence, since 14 has C symmetry (NMR), it must
1
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D. M. Guldi, A. Hirsch et al.
FULL PAPER
the unsaturated p-systems of
the planar anthracene building
blocks, makes the workup more
difficult than in the case of 7.
However, we succeeded in the
isolation of 19 by applying a
pre-purification using flash
chromatography,
through
which a mixture of pentakis-
and hexakisadducts was ob-
tained.
After
preparative
HPLC over a Nucleosil station-
ary phase using a mixture of
methylene chloride and 0.3%
ethanol, 19 was obtained in 9%
yield. Due to the poor solubility
of 19, NMR spectroscopy had
to be carried out in tetrachloro-
1
3
ethane at 808C. The C NMR
spectrum shows the typical res-
onances at d ˆ 69.5 for the
3
magnetically equivalent sp -C
atoms of the fullerene cage
and at d ˆ 140.3 and 144.6 for
2
the two types of cluster sp -C
atoms. Because the absorption
spectra of the dyads are simple
superpositions of those of the
individual units, the UV/Vis
spectrum of hexakisadduct 19
is dominated by the six anthra-
cene units. It shows a strong
absorption at lmax ˆ 264 nm and
a triple absorption at l ˆ 370,
max
Scheme 5. Cyclopropanation to give a mixture of the monoadduct 12, the bisadducts 13 ± 15, and the dimer 16.
3
89, and 411 nm, which is typ-
ical for the anthracene moiety.
be the e-isomer. The 13C NMR spectra of the bisadducts 13
and 15 reveal C symmetry. Evaluation of the UV/Vis spectra
Photophysics: Two important features of T -hexakisadducts,
2
h
as well as energy calculations (PM3) allow 13 to be assigned as
the cis-3 isomer and 15 as the trans-3 isomer.
Although anthracene derivatives are known to undergo
which are expected to have a major effect on the electron-
transfer dynamics in core ± shell structures 7, 18, and 19,
should be discussed with reference to the well-studied full-
erene monoadducts (see for example 6, 12, and 17). First, the
reduction potential shifts anodically from about À1.1 V for
the monoadduct to À1.69 V (versus ferrocene) in the
[
4‡2] cycloadditions with the [6,6]-bonds of C no indication
6
0
for the formation of the corresponding side products is found.
This is very likely to be due to the fact that here the [4‡2]
cycloaddition is highly reversible, and that the retro-reaction
occurs under the conditions of the purification.
[5, 15]
corresponding T -hexakisadduct.
In addition, the one-
h
electron reduction step is accompanied by an inherent loss of
reversibility. The second feature is the fullerene singlet
excited-state energy, which is altered in favor of an electron
transfer (vide infra). The corresponding energies result in a
strong blue shift from 1.76 to 1.89 eV in the mono- versus the
hexakisadduct.
Treatment of 9 with C60 under typical monocyclopropana-
tion conditions afforded the monoadduct 17 in 32% yield
(
Scheme 6). Subsequent addition of five diethylmalonyl
addends to the octahedral sites by using the template
mediation method led to the mixed hexakisadduct 18 in
2
3% yield (Scheme 6). The unambiguous structural assign-
In the donor± acceptor ensemble 19 the absorption features
of the anthracenoid moieties, with a 6:1 molecular ratio, direct
the 410 nm excitation exclusively to the periphery.[ The
anthracene fluorescence, which has a quantum yield (F) of
ment of these dyads was accomplished by NMR, IR, and UV/
Vis spectroscopy, and FAB mass spectrometry.
16]
The synthesis of the hexakisadduct 19 was again carried out
starting directly from C60 and using the reversible template
mediation methodology (Scheme 7). The poor solubility of
this interesting fullerene derivative, which carries covalently
bound addends that completely cover the spherical core with
0.87, is subject to
a quantitative emission quenching
À3
(F ˆ 1.1  10 ) in toluene (Figure 1a). In addition to the
460 nm anthracene emission, the familiar fullerene fluo-
rescence was found with a *0 ± 0 emission at 660 nm
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Chem. Eur. J. 2002, 8, No. 4

T -Symmetrical Hexakisadducts of C
h
979±991
60
Scheme 7. Synthesis of the hexakisadduct 19 from C60 by using the
Scheme 6. Reaction of 9 with C60 to produce monoadduct 17.
reversible template mediation methodology.
(
Figure 1b). This occurs, despite the near exclusive excitation
Since the results of the emission studies along with the
thermodynamic calculations (vide infra) suggest that an
intramolecular singlet ± singlet energy transfer occurs from
the outer shell to the inner core, further examination of this
fullerene-based hybrid was deemed necessary. This led us to
characterize the photophysics of 19 by means of time-resolved
transient absorption spectroscopy. Following the initial trans-
fer of singlet excited-state energy, which is completed within
the first 20 ps (i.e., instrumental resolution), the fullerene
singlet ± singlet transitions were seen with lmax at 530, 780, and
860 nm (Figure 2a; 50 ps time delay). The fullerene singlet
excited state deactivates by means of a spin-forbidden
at 410 nm of the anthracenoid moieties. It is important to note
that the emission pattern of the anthracenoid units remains
unchanged and is not affected by the presence of the fullerene
core. To probe the mechanism of producing the fullerene
emission, an excitation spectrum of the 660 nm emission was
taken (Figure 1a). In fact, the excitation spectrum of 19 is an
excellent match with that of a 9,10-dialkoxy-anthracene
model (9) and it also resembles the 411 nm ground-state
maximum of 9. This serves as sound support for the hypothesis
that the origin of the excited-state energy is the anthracenoid
systems. By employing reference T -C (COOEt) (F ˆ
h
66
12
À3
[2e, 17]
8
À1
1
.09 Â 10 ), with matching absorption at the 411 nm excita-
intersystem crossing
with a rate of 5.7 Â 10 s (Fig-
tion wavelength, the fullerene fluorescence quantum yields
were determined for core ± shell ensemble 19: in toluene, a F
ure 2b) to produce the corresponding triplet manifold.
The differential absorption changes, recorded immediately
after an 8 ns pulse, showed the same spectral features of the
fullerene triplet excited state as observed at the end of the
picosecond experiments (Figure 2a; 5000 ps time delay). To
be precise, a maximum located at 590 nm (Figure 3) was
observed in good agreement with the features recorded for
T -C (COOEt) , and the fullerene triplet lifetime was
À4
value of 5.5 Â 10 corresponds to only 51% of that measured
for reference T -C (COOEt) .
h
66
12
From the fluorescence quantum yield (F) and the fluo-
rescence lifetime (t ˆ 14.7 ns) of reference 9, the rate constant
10
À1
(
k ˆ 5.4  10 s ) of the intramolecular singlet ± singlet en-
ergy transfer in 19 was derived according to the following
h
66
12
expression [Eq. (1)].
estimated to be ꢀ85 ms. Similar to the fluorescence measure-
ments (vide supra), the relative triplet quantum yield of 19 is
ꢀ48%, compared with T -C (COOEt) . Thus, our analysis
k ˆ [F(9) À F(19)]/[t(9) F(19)]
Chem. Eur. J. 2002, 8, No. 4
(1)
h
66
12
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D. M. Guldi, A. Hirsch et al.
and that of the fullerene. In
FULL PAPER
turn, the endothermic electron
o
transfer (ÀDG
ꢀ À 0.2 eV)
ET
plays, at the very best, a minor
role. To activate an intramolec-
ular electron transfer in a C -
60
based core ± shell system rather
than an energy transfer, it was
deemed necessary to select a
better electron donor and/or to
excite the fullerene core. These
requisites are given in donor±
acceptor ensemble 7 employing
an o-phenylene diamine donor.
As a suitable model system
for 7 we investigated first mono-
adduct 6. Relative to the fluo-
rescence of a C (COOEt) ref-
6
1
2
erence (l ˆ 700 nm; F ˆ
max
À4 [2e, 17]
6
.0 Â 10 ),
the fullerene
6 is markedly
emission in
quenched and, more important-
ly, subject to solvent depen-
dence. In particular, a notice-
able decrease of the fluores-
cence–from n-chlorobutane
(
e ˆ 7.39) to DMF (e ˆ 36.7)–
is deduced from the data sum-
marized in Table 1 and Fig-
ure 4.[
18]
The observed trend
can be interpreted as a first
indication of an electron-trans-
fer mechanism being responsi-
ble for the rapid deactivation of
the fullerene singlet excited
state. An alternative mecha-
nism, namely, an intramolecu-
lar energy transfer from the
Figure 1. a) Emission spectra of 9 (solid line) and 19 (dashed line) in toluene with matching absorption at the
4
10 nm excitation wavelength (i.e., OD410 nm ˆ 0.7) monitoring the anthracenoid moieties emission at 460 nm.
Excitation spectra (normalized to exhibit matching signals ꢀ400 nm) of 9 (solid line; 460 nm emission) and 19
dashed line; 660 nm emission) in toluene; b) Emission spectra of T -C66(COOEt)12 reference, 18, and 19 in
(
h
toluene with matching absorption at the 410 nm excitation wavelength (i.e., OD410 nm ˆ 0.7) monitoring the
fullerene emission at 660 nm.
shows the photosensitization effect of the anthracenoid
chromophores, which act as an antenna shell and transmit
their excited-state energy to the central fullerene core.
A conceivable rationale for the moderate transfer efficien-
cy of ꢀ50% is that the chromophore units at the periphery
may be subject to interchromophore deactivations, and that,
therefore, some of the excitation energy fails to reach the
central fullerene core. To further substantiate this working
hypothesis, the efficiency of another hexakisadduct (18),
which carries only a single anthracenoid moiety, was exam-
ined and compared with that of 19. In this case, the
fullerene singlet excited state (Esinglet ˆ 1.76 eV) to the o-
phenylene diamine moiety (Esinglet ˆ 3.97 eV;
E
ˆ
triplet
3.08 eV)[ can be ruled out, based on the unfavorable
19]
thermodynamics.
To unravel the mechanism by which the fullerene singlet
excited state in dyad 6 is deactivated, the transient absorption
changes were recorded with several time delays after a short
18 ps laser pulse (355 nm). At short times (i.e., 50 ± 100 ps),
they are practically identical to those of a monoadduct
reference (C (COOEt) ) with a singlet ± singlet absorption
6
1
2
around 900 nm (Figure 5a). It is not the slow intersystem
À4
8
À1 [2e, 17]
anthracenoid emission is further quenched (F ˆ 4.1  10 ).
crossing dynamics (7.4 Â 10 s ),
which govern the life-
Most significantly, the fullerene emission quantum yield in 18
time of the singlet excited state, but a rapid intramolecular
À3
9
À1
(
F ˆ 1.04  10 ) matches that seen for fullerene reference T -
decay of the singlet ± singlet transition (THF: 1.3 Â 10 s ;
Figure 5b). Here, the singlet lifetimes are strongly reduced,
especially in solvents of high polarity. An illustration is given
in Table 1, which displays the most relevant photophysical
properties of 6.
h
À3
C (COOEt) (F ˆ 1.09  10 , Figure 1b).
66
12
The conclusion of the photophysical experiments, conduct-
ed with 18 and 19, infers that an efficient intramolecular
transfer of singlet excited-state energy from the periphery to
the core prevails. This relates predominantly to the fact that
The transient absorption changes, recorded at the conclu-
sion of this fast deactivation, are not superimposable with
those recorded for the fullerene model (C (COOEt) ), that is,
the largest energy gap opens between the two singlet excited
o
states (ÀDG
ꢀ0.8 eV), namely, that of the anthracenoid
ENT
61
2
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Chem. Eur. J. 2002, 8, No. 4

T -Symmetrical Hexakisadducts of C
h
979±991
60
Figure 3. Differential absorption spectra (UV/Visible and near-infrared)
À5
obtained upon nanosecond flash photolysis (337 nm) of ꢀ1.0 Â 10
m
solutions of 19 in nitrogen-saturated toluene with a time delay of 50 ns at
room temperature.
Figure 2. Differential absorption spectra obtained upon picosecond flash
À5
photolysis (355 nm) of ꢀ1.0 Â 10 m solutions of 19 in nitrogen-saturated
2
Figure 4. Emission spectra of C61(COOEt) reference in toluene and
toluene with a time delay of a) À 50 ps, 50 ps, and 5000 ps; b) Time-
absorption profiles at 860 nm monitoring the fullerene ISC dynamics in 19.
dyad 6 in different solvents with matching absorption at the 310 nm
excitation wavelength (i.e., OD310 nm ˆ 0.8).
the fullerene triplet excited state (see Figure 5a; 4000 ps time
delay). The fullerene triplet reveals two maxima: one in the
visible region around 380 nm and one in the near-infrared
region at 720 nm. Instead, the newly formed species shows a
sharp peak around 1030 nm, the characteristic fingerprint of
Both fingerprints (i.e., 500 and 1030 nm) were employed as
reliable probes to determine the lifetime of the associated
charge-separated state and the overall quantum yield of the
charge-separation process (see Table 1). The decay curves
closely fit a single exponential decay component. In partic-
ular, lifetimes of the order of 100 nanoseconds were derived
from the decay curves of the oxidized donor and reduced
acceptor absorption at 500 nm and 1030 nm, respectively.
Additional evidence for an intramolecular charge recombi-
nation comes from a set of experiments conducted with
different laser power and different dyad concentrations:
the one-electron reduced fullerene p-radical anion (Fig-
ure 6).[
2e, 17]
As far as the o-phenylene diamine moiety is
concerned, a transient maximum in the visible region around
00 nm corroborates the oxidation of the donor and com-
5
pletes the characterization of the charge-separated radical
pair.
Table 1. Some selected photophysical properties of dyad 6.
o
o
Solvent
e
DG
eV][a]
S
À DGET
À DGBET
Lifetime (t);
Singlet Excited
State [ns]
Quantum
Yield (F);
Fluorescence
Lifetime (t);
Fluorescence
[ns]
Lifetime (t);
Radical Pair
[ns]
Quantum Yield (F);
Radical Pair
[a]
[a]
[b]
[
[eV]
[eV]
À4
n-chlorobutane
THF
dichlorobenzene
benzonitrile
DMF
7.39
7.6
9.98
24.8
36.7
À 0.2
0.45
0.65
0.75
0.97
1.02
1.3
1.1
1.0
0.79
0.74
0.81
0.76
0.54
0.43
0.25
1.5 Â 10
0.85
0.81
0.67
0.53
0.34
0.71
À4
À 0.21
À 0.33
À 0.55
À 0.59
1.3 Â 10
89
105
120
130
À4
1.2 Â 10
0.78
0.86
0.49
À4
1.0 Â 10
À4
0.85 Â 10
[
a] See for details reference [24]. R
À
(radius acceptor) ˆ 3.6 ä; R (radius donor) ˆ 1.85 ä; RDA (donor± acceptor separation) ˆ 5.8 ä. [b] Measured by the
‡
comparative technique using the fullerene triplet characteristics as reference.
Chem. Eur. J. 2002, 8, No. 4
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0804-0985 $ 17.50+.50/0
985

D. M. Guldi, A. Hirsch et al.
FULL PAPER
Figure 6. Differential absorption spectra (UV/Visible and near-infrared)
À5
obtained upon nanosecond flash photolysis (337 nm) of ꢀ1.0 Â 10
m
solutions of dyad 6 in nitrogen-saturated benzonitrile with a time delay
of 50 ns at room temperature.
the nanosecond experiments, just the long-lived triplet ± trip-
let characteristics (lmax ˆ 590 nm) were found to a reasonably
high extent (similar to Figure 2). In comparison with dyad 6,
the lack of electron transfer relates mainly to the anodically
shifted reduction potential of the fullerene core (vide supra).
Different behavior was observed in more polar solvents:
the choice of benzonitrile or DMF results in a much stronger
o
exothermicity of the electron transfer (i.e., ÀDG values
ET
ꢀ
0.5 eV). The fluorescence properties of 7, that is, fluores-
cence quantum yield and fluorescence lifetime, now reveal
quenching with a marked solvent dependence that starts with
THF and ranges to DMF (Table 2). From these characteristics
we infer that an intramolecular electron transfer in core ± shell
ensemble 7 is, indeed, activated in benzonitrile and likewise in
DMF.
Figure 5. Differential absorption spectra obtained upon picosecond flash
À5
photolysis (355 nm) of ꢀ1.0 Â 10 m solutions of C61(COOEt)
2
reference in
nitrogen-saturated toluene with a time delay of a) À 50 ps, 100 ps, and
4
000 ps; b) Time-absorption profiles at 900 nm of C61(COOEt) reference
2
in toluene and dyad 6 in THF and DMF monitoring the fullerene singlet ±
singlet decay. decreasing the radical-pair concentration in various incre-
ments by up to 65% failed to lead to any notable changes in the charge-
recombination kinetics.
Definitive evidence in support of this hypothesis was found
in transient absorption spectroscopy. On the 50 ps timescale,
the typical fullerene singlet ± singlet absorption with maxima
at 530, 780, and 860 nm can still be seen (similar to Figure 2;
50 ps time delay). Instead of the slow intersystem crossing
dynamics (5.7 Â 10 s ) and the concomitant increase of the
triplet ± triplet absorption ꢀ590 nm, a rapid decay of the
singlet ± singlet absorption was noticed. More important is the
fact that the differential absorption changes of 7 in benzoni-
trile, noted at the end of the singlet excited-state decay, are
strikingly different from the triplet excited-state features
(compare Figure 7 and Figure 3). Additional pulse radiolytic
reduction experiments allowed us to attribute the newly
formed transient to a charge-separated state with a fullerene
The choice of the strong o-phenylene diamine donor (E1/2
0.232 V versus ferrocene) led in dyad 6 to the activation of
ˆ
8
À1
‡
an electron transfer. Encouraged by this observation, we
focussed on core ± shell ensemble 7. In toluene, n-chlorobu-
tane, and THF, the endothermic and marginally exothermic
free energy changes for an intramolecular electron transfer
o
(
ÀDG
ꢁ0.04 eV) suggest the absence of an efficient
ET
electron transfer in photoexcited 7. Indeed, the features
linked to the fullerene singlet excited state clearly lack any
solvent dependence in their decay (Table 2). Furthermore, in
Table 2. Some selected photophysical properties of core ± shell ensemble 7.
o
o
Solvent
e
DG
eV][a]
S
À DGET
À DGBET
Lifetime (t);
Singlet Excited State
Quantum Yield (F);
Fluorescence
Lifetime (t);
Fluorescence
[ns]
Product
Lifetime (t);
Radical Pair
[ns]
[a]
[a]
[
[eV]
[eV]
[ns]
À4
toluene
n-chlorobutane
THF
benzonitrile
DMF
2.39
7.39
7.6
24.8
36.7
1.2
À 1.14
0.03
0.04
0.45
0.51
0.64
0.62
0.62
0.36
0.27
3.1 Â 10
1.14
1.02
0.98
0.36
0.27
triplet
triplet
triplet
radical pair
radical pair
À4
À 0.2
3.9 Â 10
À4
À 0.21
À 0.55
À 0.59
3.9 Â 10
À4
1.44
1.39
2.1 Â 10
2380
1050
À4
1.7 Â 10
[
a] See for details reference [24]. R
À
(radius acceptor) ˆ 3.6 ä; R
‡
(radius donor) ˆ 1.85 ä; RDA (donor± acceptor separation) ˆ 5.8 ä.
0947-6539/02/0804-0986 $ 17.50+.50/0 Chem. Eur. J. 2002, 8, No. 4
9
86
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002

T -Symmetrical Hexakisadducts of C
h
979±991
60
o
Figure 7. Differential absorption spectra (UV/Visible and near-infrared)
Figure 8. Driving-force (ÀDGBET† dependence of intramolecular charge-
À5
obtained upon nanosecond flash photolysis (337 nm) of ꢀ1.0 Â 10
m
recombination rate constants in dyad 6 (white circles) and in 7 (black
circles). The line represents the best fit (l ˆ 0.89 eV and Vˆ 0.22 cm ).
À1
solutions of 7 in nitrogen-saturated benzonitrile with a time delay of
0 ns at room temperature.
5
transmitting electrons and singlet excited-state energy, respec-
[
20]
p-radical anion absorption (ꢀ900 nm).
Complementary
tively, to the redox- and photoactive T -hexakisadduct core.
h
nanosecond experiments give rise to lifetimes (t) of 2.38 ms
and 1.05 ms in benzonitrile and DMF, respectively. The charge
recombination processes obey in both cases a first-order rate
law and lead to a complete recovery of the singlet ground
state.
Photoinduced electron transfer, in the core shell ensem-
ble 7, generates a remarkably long-lived charge-separated
state (t ˆ 2380 ns in benzonitrile). Its energy (1.44 eV) is
notably higher than that in the analogous mono- and bis-
[12]
adducts (0.79 eV). This shifts the back electron transfer in 7
The lifetimes of the charge-separated states can be corre-
lated with the solvent polarity. The dependence of kBET (t ˆ
far into the ™Marcus-inverted∫ region, which, at least in part,
decelerates the energy-wasting charge recombination. Of
apparently equal importance is the interruption of the full-
erene p-system that leaves only isolated benzene subunits
behind for stabilization of the electron on the fullerene (i.e.,
pristine C versus hexakisadduct). In terms of storing excited-
1
/kBET) versus free energy changes (Table 2) indicates stabi-
o
lizing effects for the charge-separated state at higher ÀDG
BET
values in core ± shell ensemble 7. These are clear attributes of
the ™Marcus-inverted∫ region, the highly exergonic region
6
0
o
(
ÀDG > l), where the electron-transfer rates start to de-
state energy, the high-lying level of the fullerene p-radical
[21]
crease with increasing free energy changes. In contrast, the
lifetime of the radical pair in dyad 6 grows gradually from the
moderately to the strongly polar solvents, and this indicates
that these rates are in the ™Marcus-normal∫ region (Table 1).
In general, the driving forces of the charge-recombination
processes in 7 (ꢀ1.4 eV) are markedly larger than those in 6
anion in T -hexakisadducts implies a net gain of nearly 0.7 eV
h
in comparison with the monoadduct.
Based on the chemistry of the terminal groups and the
highly symmetric three-dimensional architectures, even high-
er generation dendrimers derived from 7 and 19 can be
envisioned. Since the core retains some of C ×s electron- and
6
0
(
0.74 ± 1.1 eV), which support the above assignment regarding
energy-acceptor features and is also sufficiently shielded from
the surrounding medium, several useful features might be
realized, such as energy collection/transduction and amplifi-
cation of electron transfer. For example, while evidence for
dialkoxyanthracene moieties in 19 can be seen sufficiently in
the UV and near-visible part of the spectrum, further
extension into the visible and near-infrared section will
constitute the next design step. Furthermore, their ability to
function as hosts for a range of ions and molecules points to its
unique versatility for practical applications: p ± p association
with the fullerene core and weak van der Waals forces are
realistic possibilities for facilitating trapping or encapsulating
suitable guests within the interior of the higher generation
systems. Currently, we are intensifying our research to explore
these issues.
the charge-recombination kinetics being either in the ™Mar-
cus-inverted∫ or ™Marcus-normal∫ region.
To quantify the driving-force dependence on the rate
constants (k ), the semi-classical Marcus equation was
ET
employed.[ Figure 8 shows the log kBET versus ÀDG
22]
o
plot
BET
for the different donor± acceptor ensembles. From the best
fits of the driving-force dependence on ETrates, the following
values for the reorganization energies (l) and electronic
À1
couplings (V) were derived: l ˆ 0.89 eV and Vˆ 0.22 cm .
The reorganization energy is smaller than those reported
previously for porphyrin ± quinone and zinc porphyrin ± free-
base porphyrin-linked systems, which are typically in the
range between 0.8 and 1.2 eV,[ but larger than in a zinc
tetraphenylporphyrin ± fullerene dyad (0.67 eV).[
22]
23]
Conclusion
Experimental Section
In summary, we demonstrated that core ± shell ensembles 7
and 19 function as energy- and electron-transducer systems,
General: Picosecond laser flash photolysis experiments were carried out
with 355 nm laser pulses from a mode-locked, Q-switched QuantelYG-501
Chem. Eur. J. 2002, 8, No. 4
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0804-0987 $ 17.50+.50/0
987

D. M. Guldi, A. Hirsch et al.
FULL PAPER
À1
DP Nd:YAG laser system (pulse width 18 ps, 2 ± 3 mJpulse ). Nanosecond
laser studies were performed with laser pulses from a Molectron UV-400
product was separated by flash chromatography (toluene/ethyl acetate
16:1). Yield: 60 mg (0.06 mm, 23%), red brownish solid.
À1
nitrogen laser system (337.1 nm, 8 ns pulse width, 1 mJpulse ). The
photomultiplier output was digitized with a Tektronix7912AD program-
mable digitizer.
1H NMR (400 MHz, CDCl
3
, 258C): d ˆ 2.05 (m, 4H; CH
), 4.44 (t, J ˆ 5.4 Hz, 4H; CH
H; CH); C NMR (100.50 MHz, CDCl
, 258C): d ˆ 25.41 (2C; CH
), 51.95 (1C; bh; bridge headÀC), 65.09
2
), 2.81 (s, 6H;
), 6.99 (m,
),
CH
4
3
), 3.45 (t, J ˆ 6.6 Hz, 4H; CH
2
2
13
3
2
Pulse radiolysis experiments were performed by utilizing 50 ns pulses of
MeV electrons from a ModelTB-8/16-1S Electron Linear Accelerator.
39.69 (2C; CH
(2C; CH
3
), 49.18 (2C; CH
), 71.50 (2C; sp -C60 C), 119.99 (2C; CH), 122.77 (2C; CH),
2
3
8
2
À
.À
Dosimetry was based on the oxidation of SCN to (SCN)
aqueous, N
2
, which in
139.06, 140.94, 141.93, 142.20, 143.01, 143.06, 143.89, 144.60, 144.69, 144.87,
2
O-saturated solutions takes place with G ˆ 0.6 mm per joule of
145.16, 145.26, 145.49 (sp C), 163.53 (2C; CˆO); MS (FAB): m/z (%): 1039
2
‡
absorbed energy. The radical concentration generated per pulse amounted
[M] ; IR (KBr): nÄ ˆ 3059, 2951, 2925, 2841, 2794, 1744, 1494, 1449, 1428,
À1
to (1 ± 3) mm for all the systems investigated in this study.
1267, 1232, 1203, 1186, 1056, 906, 803, 730 cm ; UV/Vis (CH
2
Cl
2
): lmax
(
e) ˆ 258 (115000), 326 (33000), 426 (2200), 486 nm (1400).
Fluorescence lifetimes were measured with a Laser Strope Fluorescence
Lifetime Spectrometer (Photon Technology International) with 337 nm
laser pulses from a nitrogen laser fiber-coupled to a lens-based T-formal
sample compartment equipped with a stroboscopic detector. Details of the
Laser Strobe systems are described on the manufacturer×s web site,
http://www.pti-nj.com.
Hexakisadduct 7: Compound 9,10-dimethylanthracene (86 mg, 0.42 mm)
was added to a solution of C60 (30 mg, 0.042 mm) in pure toluene (50 mL)
under a nitrogen atmosphere, and the mixture was stirred for three hours.
Then diamine 1 (133 mg, 0.42 mm), tetrabromomethane (138 mg, 0.42 mm),
and DBU (84 mg, 0.55 mm) were added. After stirring over night the
mixture was filtered. Separation and purification of the product was
achieved by flash chromatography (toluene/triethylamine 19:1) followed
by preparative HPLC (Gromsil-Amino-Phase, toluene). Yield: 13 mg
Emission spectra were recorded with a SLM8100 Spectrofluorometer. The
experiments were performed at room temperature. Each spectrum
represents an average of at least five individual scans, and appropriate
corrections were applied whenever necessary.
1H NMR and 13C NMR: JeolJNMEX400 and JeolJNMGX400; MS:
Varian Mat311A (EI) and Finnigan MAT900 (FAB); FT IR: Bruker
Vector22; UV/Vis: Shimadzu UV3102PC; analytical HPLC: Shimadsu
Sil10A, SPD10A, CBM10A, LC10 ATFRC 10A; preparative HPLC:
Shimadsu Sil10A, SPD10A, CBM10A, LC8A, FRC10A; TLC: Macher-
ey-Nagel, Alugram SilG/UV254. Reagents used were commercially
available reagent grade and were purified according to standard proce-
dures.
(
0.005 mm, 12%), yellow solid.
1H NMR (400 MHz, CDCl
, 258C): d ˆ 1.90 (m, 24H; CH
CH ), 4.16 (t, J ˆ 5.2 Hz, 24H; CH
), 3.29 (t, J ˆ 6.2 Hz, 24H; CH
m, 24H; CH); C NMR (100.50 MHz, CDCl
, 258C): d ˆ 25.33 (12C;
), 45.21 (6C; BkÀC), 49.21 (12C; CH
), 64.78 (12C;
3
2
), 2.72 (s, 36H;
), 6.93
3
3
2
1
3
(
3
CH
CH
(
(
1
(
2
2
), 39.73 (12C; CH
3
2
3
), 68.96 (12C; sp -C60 C), 119.93 (12C; CH), 122.66 (12C; CH), 140.94
2
2
24C; sp C), 145.49 (12C; C), 145.70 (24C; sp -C), 163.62 (12C; CˆO); MS
‡
FAB): m/z (%): 2630 [M] , 1316; IR (KBr): nÄ ˆ 3056, 2956, 2844, 2797,
À1
746, 1590, 1495, 1451, 1265, 1210, 1125, 1062, 750, 715 cm ; UV/Vis
CH
2
Cl
2
): lmax (e) ˆ 240 (141000), 270 (92000), 334 nm (34000).
Nitrogen-saturated
Cyclic malonates 1, 4, and 5: A solution of diol 3 (1.14 g, 4.5 mm) in dry
dichloromethane (300 mL) was stirred, and a solution of malonyl dichlo-
ride (650 mg, 4.5 mm) was added dropwise over 16 hours under a nitrogen
atmosphere. Afterwards the solvent was removed under reduced pressure.
Separation and purification of the products were achieved by flash
chromatography (toluene/triethylamine 19:1) followed by preparative
HPLC (Gromsil-Amino-Phase, toluene).
9
,10-Bis(3-hydroxypropoxy)anthracene 8:
water
(
200 mL) and pure dichloromethane (200 mL) were added to a mixture
of 9,10-anthraquinone (4.16 g, 20 mm), sodium dithionite (85%, 8.2 g,
0 mm), and Adogen 464 (methyltrialkyl (C8-C10) ammonium chloride)
7.4 g, 16 mmol), and the mixture was stirred for 5 minutes. Then sodium
hydroxide (8.0 g, 200 mm) was added, and stirring was continued for
0 minutes, and the mixture turned dark red. Compound 3-iodopropanol
18.2 g, 100 mm) was added dropwise, and the mixture was stirred for
6 hours at room temperature. The phases were separated, and the aqueous
4
(
1
(
1
Yields: 1: 150 mg (0.47 mm, 10%) colorless oil; 4: 250 mg (0.39 mm, 16%),
colorless oil; 5: 50 mg (0.05 mm, 3%), slightly yellow oil.
1
phase was washed with dichloromethane (2 Â 200 mL). The organic phases
were combined, washed with water (2 Â 100 mL), and dried over magne-
sium sulfate. The filtrate was reduced to 100 mL, and the product was
precipitated at À258C. Further purification of the crude product was
achieved by flash chromatography (silica gel, dichloromethane/ethyl
acetate 3:1). Yield: 2.1 g (6.4 mm, 32%), yellow solid, melting point 1488C.
Compound 1: H NMR (400 MHz, CDCl
3
, 258C): d ˆ 1.83 (m, 4H; CH
), 3.28 (s, 2H; CH ), 4.11 (t,
), 6.92 (s, 4H; CH); C NMR (100.50 MHz, CDCl
), 39.46 (2C; CH
2
),
2
.70 (s, 6H; CH
3
), 3.24 (t, J ˆ 6.9 Hz, 4H; CH
2
2
1
3
J ˆ 5.4 Hz, 4H; CH
2
3
,
2
4
1
58C): d ˆ 25.52 (2C; CH
2
3
), 42.32 (1C; OˆCCH CˆO),
2
9.32 (2C; CH ), 63.21 (2C; CH
2
2
), 119.84 (2C; CH), 122.46 (2C; CH),
‡
45.57 (2C; C), 166.36 (2C; CˆO); MS (FAB): m/z (%): 320 [M] ; IR
(
1
film): nÄ ˆ 3057, 2958, 2845, 2798, 1733, 1590, 1495, 1452, 1415, 1382, 1304,
1
H NMR (400 MHz, [D ]DMSO, 258C): d ˆ 2.12 (m, 2H; CH ), 3.78 (q, J ˆ
6
2
À1
266, 1185, 1128, 1064, 1035, 988, 960, 887, 751, 683 cm ; UV/Vis (CH
2
Cl
2
):
5.5 Hz, 2H; OCH ), 4.19 (t, J ˆ 6.3 Hz, 2H; OCH ), 4.66 (t, J ˆ 5.2 Hz, 2H;
2
2
l
max (e) ˆ 239 (33000), 267 nm (5700).
OH), 7.54 (m, 4H; CH), 8.27 (m, 4H; CH); 13C NMR (100 MHz,
1
[D ]DMSO, 258C): d ˆ 33.23 (2C; CH ), 57.43 (2C; OCH ), 72.82 (2C;
Compound 4: H NMR (400 MHz, CDCl
2
J ˆ 6.5 Hz, 8H; CH
3
, 258C): d ˆ 1.83 (m, 8H; CH
), 3.32 (s, 4H; CH
), 6.92 (s, 8H; CH); C NMR (100.50 MHz, CDCl
58C): d ˆ 26.01 (4C; CH ), 39.73 (4C; CH
), 41.41 (2C; OˆCCH CˆO),
0.33 (4C; CH ), 63.99 (4C; CH ), 119.60 (4C; CH), 122.40 (4C; CH),
2
),
6
2
2
.71 (s, 12H; CH
3
), 3.14 (t, J ˆ 7.2 Hz, 8H; CH
2
2
), 4.14 (t,
OCH
2
), 122.41 (4C; arom. C), 124.53 (4C; arom. C), 125.58 (4C; arom. C),
‡
1
3
146.80 (2C; arom. C); MS (FAB): m/z (%): 326 [M] , 267, 209, 152; IR
(
1
2
3
,
KBr): nÄ ˆ 3313, 3068, 3053, 3038, 2927, 2875, 1654, 1522, 1518, 1434, 1424,
2
5
1
2
3
2
À1
402, 1368, 1344, 1169, 1091, 1067, 973, 936, 778, 754, 676, 608 cm ; UV/Vis
2
2
‡
(CH Cl ): l
max
(e) ˆ 262 (82000), 366 (3700), 384 (5500), 406 nm (4800).
45.40 (4C; C), 166.56 (4C; CˆO); MS (FAB): m/z (%): 642 [M‡H] ; IR
2
2
(
film): nÄ ˆ 3057, 2956, 2844, 2799, 1733, 1590, 1495, 1452, 1413, 1385, 1334,
Cyclic malonates 9 and 10: Diol 8 (1.2 g, 3.7 mm) was dissolved in dry
dichloromethane (500 mL) under a nitrogen atmosphere. A solution of
malonyl dichloride (540 mg, 3.7 mm) in dry dichloromethane (300 mL) was
added dropwise over 24 hours. The reaction was controlled by TLC
À1
1
272, 1185, 1098, 1056, 1037, 958, 887, 752 cm ; UV/Vis (CH
2
Cl
2
):
l
max (e) ˆ 238 nm (24000), 268 (12000).
1
Compound 5: H NMR (400 MHz, CDCl
2
J ˆ 6.6 Hz, 12H; CH
3
, 258C): d ˆ 1.81 (m, 12H; CH
), 3.14 (t, J ˆ 7.1 Hz, 12 H ; CH ), 3.32 (s, 6H; CH
), 6.91 (s, 12H; CH); C NMR (100.50 MHz, CDCl
), 39.74 (6C; CH
2
),
(
dichloromethane/ethyl acetate 19:1). Separation of the products was
.72 (s, 18H; CH
3
2
2
), 4.14 (t,
1
3
achieved by flash chromatography with gradient elution (silica gel,
dichloromethane/ethyl acetate 19:1 ± 9:1). The separated products were
washed with pentane and dried in a vacuum.
2
3
,
2
5
1
58C): d ˆ 26.03 (6C; CH
2
3
), 41.39 (3C; OˆCCH CˆO),
2
0.16 (6C; CH ), 63.98 (6C; CH
2
2
), 119.59 (6C; CH), 122.36 (6C; CH),
‡
45.24 (6C; C), 166.50 (6C; CˆO); MS (FAB): m/z (%): 962 [M‡H] ; IR
Yields: 9: 50 mg (0.38 mm, 10%), yellow solid, melting point 2888C; 10:
200 mg (0.25 mm, 13%), yellow solid, melting point: 1938C.
(
film): nÄ ˆ 3057, 2957, 2845, 2800, 1733, 1590, 1495, 1455, 1413, 1385, 1272,
À1
1
185, 1098, 1037, 957, 752, 687 cm ; UV/Vis (CH
2
Cl
2
): lmax (e) ˆ 238
1
Compound 9: H NMR (400 MHz, CDCl
3
, 258C): d ˆ 2.06 (m, 4H; CH
CO), 3.83 (t, J ˆ 6.0 Hz, 4H; CH
OCˆO), 4.54 (t, J ˆ
), 7.44 (m, 4H; arom. H), 8.25 (m, 4H; arom. H);
, 258C): d ˆ 29.63 (2C; CH ), 40.68 (1C;
OCˆO), 72.23 (2C; OCH
), 122.80 (4C; CH),
124.46 (4C; C), 125.05 (4C; CH), 147.65 (2C; C), 165.44 (2C; CˆO); MS
2
),
(
33000), 268 nm (17000).
Monoadduct 6: The diamine 1 (110 mg, 0.34 mm), tetrabromomethane
115 mg, 0.34 mm), and DBU (65 mg, 0.42 mm) were added to a solution of
60 (190 mg, 0.26 mm) in pure toluene (130 mL) under nitrogen
atmosphere. After stirring overnight the mixture was filtered, and the
2
.53 (s, 2H; OCCH
2
2
6.0 Hz, 4H; OCH
2
1
3C NMR (100 MHz, CDCl
(
C
3
2
a
OCCH
2
CO), 61.74 (2C; CH
2
2
988
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0804-0988 $ 17.50+.50/0
Chem. Eur. J. 2002, 8, No. 4

T -Symmetrical Hexakisadducts of C
h
979±991
60
‡
(
1
1
FAB): m/z (%): 394 [M] ; IR (KBr): nÄ ˆ 3065, 3049, 2960, 2894, 1743,
Yields: 16: 55 mg (0.028 mm, 3%, T
62 mg (0.048 mm, 5%, T
(0.090 mm, 9%, T
R
ˆ 2.3 min), red brownish solid; 13:
676, 1618, 1462, 1436, 1407, 1380, 1361, 1348, 1331, 1283, 1187, 1171, 1154,
129, 1084, 1059, 995, 930, 781, 689 cm ; UV/Vis (CH
106000), 372 (5000), 390 (5900), 410 (5000).
R
ˆ 6.0 min), red brownish solid; 14: 112 mg
À1
2
Cl
2
): lmax (e) ˆ 264
R
ˆ 7.3 min), red brownish solid; 15: 34 mg (0.027 mm,
(
3%, T
R
ˆ 8.4 min), red brownish solid.
1
1
Compound 10: H NMR (400 MHz, CDCl
3
, 258C): d ˆ 2.13 (m, 8H; CH
OCˆO), 4.43 (t, J ˆ
), 7.32 (m, 8H; arom. CH), 8.01 (m, 8H; arom. CH);
C NMR (100 MHz, CDCl ), 42.01 (2C;
, 258C): d ˆ 29.42 (4C; CH
OCCH CO), 62.58 (4C; CH ), 122.27 (8C; CH),
OCˆO), 71.54 (4C; OCH
24.78 (8C; C), 125.34 (8C; CH), 146.92 (4C; C), 166.30 (4C; CˆO); MS
2
),
Compound 16: H NMR (400 MHz, CDCl , 258C): d ˆ 2.59 (m, 4H; CH ),
3
2
3
.50 (s, 4H; OCCH
.2 Hz, 8H; OCH
2
CO), 3.87 (t, J ˆ 6.1 Hz, 8H; CH
2
3.97 (s, 6H; CH ), 4.33 (t, J ˆ 6.2 Hz, 4H; OCH ), 4.96 (t, J ˆ 6.0 Hz, 4H;
13
3
2
6
2
2 3
OCH ), 7.52 (m, 4H; CH), 8.27 (m, 4H; CH); C NMR (100 MHz, CDCl ,
1
3
258C): d ˆ 29.58 (2C; CH ), 51.78 (2C; BkÀC), 54.02 (2C; CH ), 64.42 (2C;
3
2
2
3
3
CH OCˆO), 71.16 (4C; C -sp -C), 71.98 (2C; OCH ), 122.22 (4C; arom.
2
2
2
2
60
2
1
(
1
1
7
CH), 124.74 (4C; arom. C), 125.62 (4C; arom. CH), 138.48, 138.85, 140.57,
141.48, 141.59, 141.85, 142.63, 142.70, 142.78, 143.51, 143.58, 144.24, 144.31,
‡
FAB): m/z (%): 788 [M] ; IR (KBr): nÄ ˆ 3069, 2966, 2928, 2881, 1758, 1729,
2
620, 1476, 1458, 1436, 1407, 1387, 1364, 1348, 1324, 1304, 1275, 1223, 1215,
144.37, 144.59, 144.68, 144.75, 144.81, 144.84, 144.88 (C -sp -C), 146.91 (2C;
6
0
160, 1109, 1087, 1069, 1044, 1018, 980, 940, 892, 861, 853, 779, 764,
ArCÀO), 163.39 (2C; CˆO), 163.81 (2C; CˆO); MS (FAB): m/z (%): 1964
À1
‡
52 cm ; UV/Vis (CH
2
Cl
2
): lmax (e) ˆ 254 (145000), 262 (173000), 350
[M‡H] , 720; IR (KBr): nÄ ˆ 2924, 1744, 1636, 1430, 1266, 1235, 1186, 1062,
À1
(
5100), 366 (10000), 384 (14900), 406 nm (12700).
948, 888, 744, 704 cm ; UV/Vis (CH Cl ): l
(e) ˆ 262 (182000), 325
2
2
max
(
46000), 403 (8800), 426 nm (4700).
1
-{3-[(10-{3-[(3-Methoxy-3-oxopropanoyl)oxy]propoxy}-9-anthryl)oxy]-
propyl}3-methylmalonate 11: Methyl malonyl chloride (169 mg, 1.22 mm)
was added dropwise to a solution of diol 8 (200 mg, 0.61 mm) and pyridine
1
Compound 13:
H NMR (400 MHz, CDCl , 258C): d ˆ 2.53 (m, 4H; CH ),
3
2
3.92 (m, 2H; OCH ), 4.10 (m, 2H; OCH ), 4.16 (s, 6H; CH ), 4.47 (m, 2H;
2
2
3
(
100 mg, 1.22 mm) in dry dichloromethane (100 mL) under a nitrogen
2 2
OCH ), 4.97 (m, 2H; OCH ), 7.26 (m, 2H; CH), 7.48 (m, 2H; CH), 7.93 (d,
atmosphere. The mixture was stirred at room temperature for two hours,
and the progress of the reaction was monitored by TLC. The product was
isolated by flash chromatography (silica gel, dichloromethane/ethyl acetate
J ˆ 8.8 Hz, 2H; CH), 8.42 (d, J ˆ 8.8 Hz, 2H; CH); 13C NMR (100 MHz,
CDCl , 258C): d ˆ 29.14 (2C; CH ), 51.39 (2C; BkÀC), 54.06 (2C; CH ),
3
2
3
3
3
64.61 (2C; CH OCˆO), 70.79 (2C; C -sp
-C), 71.17 (2C; C -sp
-C), 74.36
2
60
60
1
9:1) and dried in a vacuum. Yield: 230 mg, (0.44 mm, 72%), yellow solid,
(OCH ), 122.19 (2C; arom. CH), 122.66 (2C; arom. CH), 124.59 (2C;
2
melting point 798C.
arom. C), 124.84 (2C; arom. C), 125.48 (2C; arom. CH), 125.80 (2C; arom.
1H NMR (400 MHz, CDCl
CH), 137.32, 137.72, 139.30, 141.21, 141.51, 141.69, 142.18, 142.33, 142.45,
3
, 258C): d ˆ 2.39 (m, J ˆ 6.4 Hz, 4H; CH
), 4.24 (t, J ˆ 6.4 Hz, 4H; CH ), 4.63 (t, J ˆ
), 7.49 (m, 4H; CH), 8.23 (m, 4H; CH); C NMR
, 258C): d ˆ 29.63 (2C; CH
), 41.40 (2C; OˆCCH CˆO),
OCˆO), 71.78 (2C; OCH
), 122.46 (4C;
2
), 3.46
1
42.97, 143.21, 143.32, 143.67, 143.82, 144.26, 144.46, 144.84, 144.94, 145.32,
(
s, 4H; CH
2
), 3.69 (s, 6H; CH
3
2
2
1
3
145.46, 145.56, 145.94, 146.14, 146.31, 146.38, 146.52, 146.73, 147.11 (C -sp -
6
.4 Hz, 4H; CH
2
60
C), 148.01 (2C; ArCÀO), 162.87 (2C; CˆO), 163.90 (2C; CˆO); MS
(
5
100 MHz, CDCl
2.53 (2C; CH
3
2
2
‡
(
1
FAB): m/z (%): 1243 [M‡H] , 720; IR (KBr): nÄ ˆ 3065, 2960, 1748, 1435,
3
), 62.56 (2C; CH
2
2
À1
CH), 125.02 (4C; C), 125.46 (4C; CH), 147.15 (2C; PhÀCÀO), 166.53 (2C;
366, 1349, 1260, 1228, 1102, 1063, 1031, 803, 757, 708 cm ; UV/Vis
‡
(CH Cl ): l (e) ˆ 254 (117000), 262 (118000), 408 (5700), 488 nm (2300).
CˆO), 166.90 (2C; CˆO); MS (FAB): m/z (%): 526 [M] ; IR (KBr): nÄ ˆ
2
2
max
3
1
062, 2996, 2961, 2936, 2884, 1753, 1677, 1617, 1437, 1407, 1347, 1286, 1194,
155, 1066, 1018, 942, 784, 753, 676 cm ; UV/Vis (CH
1
Compound 14: H NMR (400 MHz, CDCl
.62 (m, 1H; CH ), 2.76 (m, 1H; CH ), 3.76 (m, 1H; OCH
OCH ), 4.09 (s, 3H; CH ), 4.12 (s, 3H; CH
1H; OCH ), 4.42 (m, 1H; OCH
OCH ), 5.17 (m, 1H; OCH
1H; CH), 7.94 (d, J ˆ 8.8 Hz, 1H; CH), 8.02 (d, J ˆ 8.1 Hz, 1H; CH), 8.10
3
, 258C): d ˆ 2.51 (m, 2H; CH
), 3.96 (m, 1H;
), 4.17 (m, 1H; OCH ), 4.33 (m,
), 4.90 (m, 1H;
2
),
À1
2
Cl
2
): lmax (e) ˆ 262
2
2
2
2
(
94000), 348 (2400), 364 (4100), 384 (6100), 405 nm (5300).
2
3
3
2
Monoadduct 12: DBU (29 mg, 0.19 mm) was added dropwise to a solution
of C60 (122 mg, 0.17 mm), bismalonate 11 (90 mg, 0.17 mm), and tetrabro-
momethane (57 mg, 0.17 mm) in dry toluene (100 mL) under a nitrogen
atmosphere. The mixture was stirred at room temperature for 16 hours, and
the progress of the reaction was monitored by TLC. The product was
isolated by flash chromatography (silica gel, toluene/ethyl acetate 19:1).
Finally, the product was washed with pentane, dried in a vacuum, and
stored under nitrogen. Yield: 45 mg (0.036 mm, 21%), red brownish solid.
2
2
), 4.63 (m, 1H; OCH
2
2
2
), 7.23 (m, 2H; CH), 7.34 (m, 1H; CH), 7.47 (m,
1
3
(d, J ˆ 8.1 Hz, 1H; CH), 8.58 (d, J ˆ 8.8 Hz, 1H; CH); C NMR (100 MHz,
CDCl
3
, 258C): d ˆ 29.19 (1C; CH
2
2
), 29.42 (1C; CH ), 51.51 (2C; bridge-
head-C), 54.05 (2C; CH
3
), 64.65 (1C; CH
2
OC
ˆ
O), 65.33 (1C; CH OCˆO),
2
3
70.79, 70.88, 70.95 (C60-sp -C), 73.16 (1C; OCH
2
2
), 74.64 (1C; OCH ),
122.07, 122.27, 123.20, 124.21, 124.85, 125.45, 125.54, 126.04 (arom. C),
1
1
1
1
1
36.56, 136.60, 137.95, 138.59, 140.05, 140.72, 140.82, 141.33, 141.64, 141.68,
41.77, 142.26, 142.81, 142.90, 143.19, 143.26, 143.37, 143.56, 143.72, 143.78,
43.85, 144.01, 144.14, 144.31, 144.54, 145.07, 145.18, 145.68, 145.73, 146.02,
1H NMR (400 MHz, CDCl
CH ), 3.46 (s, 2H; OCCH CO), 3.70 (s, 3H; CH
), 4.35 (t, J ˆ 6.4 Hz, 2H; OCH
), 4.98 (t, J ˆ 6.2 Hz, 2H; OCH ), 7.50 (m, 4H; CH), 8.22 (m,
H; CH), 8.30 (m, 2H; CH); C NMR (100 MHz, CDCl
, 258C): d ˆ 29.63
), 29.81 (1C; CH ), 41.37 (1C; OCCH
CO), 52.02 (1C; BkÀC),
2.52 (1C; CH ), 53.98 (1C; CH ), 62.53 (1C; CH
OCˆO), 64.56 (1C;
, 258C): d ˆ 2.39 (m, 2H; CH
), 3.96 (s, 3H; CH
), 4.63 (t, J ˆ 6.3 Hz,
), 2.60 (m, 2H;
3
2
2
2
3
3
), 4.24 (t,
J ˆ 6.2 Hz, 2H; OCH
2
2
2
46.13, 146.33, 146.41, 146.54, 146.86, 147.01, 147.12 (C60-sp -C), 147.56,
2
2
(
5
CH
H; OCH
2
2
47.61 (ArCÀO), 162.67, 163.82, 163.96 (CˆO); MS (FAB): m/z (%): 1243
1
3
3
‡
[
1
M‡H] , 720; IR (KBr): nÄ ˆ 3065, 2950, 2881, 1747, 1433, 1364, 1349, 1234,
1C; CH
2
2
2
À1
104, 1062, 1032, 756, 731, 708, 671 cm ; UV/Vis (CH
2
Cl
2
): lmax (e) ˆ 254
3
3
2
(
139000), 262 (139000), 408 (6900), 486 nm (2600).
3
OCˆO), 71.43, 71.81, 72.07 (OCH
‡ C60-sp -C), 122.44 (2C; arom.
2
2
1
CH), 122.49 (2C; arom. CH), 125.03 (4C; arom. C), 125.49 (2C; arom.
CH), 125.65 (2C; arom. CH), 138.84, 139.08, 140.85, 140.89, 141.77, 141.90,
Compound 15: H NMR (400 MHz, CDCl
3
, 258C): d ˆ 2.63 (m, 2H; CH
), 4.26 (m, 2H;
), 7.33 (m, 4H; CH), 8.06
, 258C): d ˆ
), 65.27 (2C;
OC O), 70.62 (2C; C60-sp -C), 71.29 (2C; C60-sp -C), 74.36 (2C;
OCH ), 122.55 (4C; arom. CH), 124.53 (2C; arom. C), 124.98 (2C; arom.
2
),
2.74 (m, 2H; CH
2
), 3.94 (m, 2H; OCH
2
), 4.23 (s, 6H; CH
3
1
1
42.13, 142.17, 142.94, 142.99, 143.05, 143.80, 143.85, 144.52, 144.62, 144.65,
44.87, 144.98, 145.07, 145.11, 145.16, 145.20, 145.26 (C60-sp -C), 147.10 (1C;
OCH ), 4.57 (m, 2H; OCH
2
2
), 4.91 (m, 2H; OCH
2
2
(m, 2H; CH), 8.16 (m, 2H; CH); 13C NMR (100 MHz, CDCl
3
ArCÀO), 147.27 (1C; ArCÀO), 163.58 (1C; CˆO), 164.00 (1C; CˆO),
2 3
29.49 (2C; CH ), 50.24 (2C; bridgehead-C), 54.25 (2C; CH
‡
ˆ
3
3
1
66.50 (1C; CˆO), 166.87 (1C; CˆO); MS (FAB): m/z (%): 1244 [M] , 720;
CH
2
IR (KBr): nÄ ˆ 2960, 1744, 1433, 1406, 1347, 1266, 1234, 1066, 803, 774, 702,
2
À1
6
(
09 cm ; UV/Vis (CH
2
Cl
2
): lmax (e) ˆ 262 (199000), 326 (34000), 382
C), 125.42 (2C; arom. CH), 125.76 (2C; arom. CH), 135.39, 135.61, 139.99,
140.86, 141.48, 141.63, 141.77, 142.07, 142.19, 142.50, 142.88, 143.14, 143.20,
12600), 405 (8500), 426 (2800), 489 (1800), 688 nm (400).
1
1
1
7
1
43.47, 143.53, 143.91, 144.06, 144.29, 144.44, 144.68, 144.79, 145.09, 145.35,
Fullerene adducts 13, 14, 15, and 16: [60]Fullerene (720 mg, 1.0 mm) was
dissolved in pure toluene (400 mL) under a nitrogen atmosphere and under
exclusion of light. Then, malonate 11 (526 mg, 1.0 mm) and tetrabromo-
methane (663 mg, 2.0 mm) were added. DBU (335 mg, 2.2 mm) was added
slowly over 5 hours. The mixture was stirred for 20 hours, and the course of
the reaction was monitored by TLC (silica gel, toluene/ethyl acetate 19:1).
The mixture was reduced to 100 mL, and it was preselected by flash
chromatography (silica gel, toluene/ethyl acetate 19:1). The separation of
the products was achieved by preparative HPLC (nucleosil, toluene/ethyl
acetate 99:1). The products were washed with pentane, dried in a vacuum,
and stored under nitrogen.
2
45.43, 146.00, 146.26, 146.78, 146.88 (C60-sp -C), 147.26 (2C; ArCÀO),
‡
64.26 (2C; CˆO), 164.54 (2C; CˆO); MS (FAB): m/z (%): 1243 [M‡H] ,
20; IR (KBr): nÄ ˆ 3062, 3022, 2950, 2924, 2877, 1747, 1434, 1362, 1238, 1107,
À1
062, 1030, 776, 736, 702, 668 cm ; UV/Vis (CH
2
Cl
2
): lmax (e) ˆ 262
(
150000), 383 (11900), 405 (7400), 430 (3100), 486 nm (2100).
Monoadduct 17: DBU (30 mg, 0.2 mm) was added dropwise to a solution of
[60]fullerene (100 mg, 0.14 mm), malonate 9 (65 mg, 0.16 mm), and tetra-
bromomethane (55 mg, 0.16 mm) in pure toluene (100 mL) under a
nitrogen atmosphere. The mixture was stirred for 16 hours, and the course
of the reaction was monitored by TLC (silica gel, toluene/ethyl acetate
Chem. Eur. J. 2002, 8, No. 4
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0804-0989 $ 17.50+.50/0
989

D. M. Guldi, A. Hirsch et al.
FULL PAPER
1
9:1). The product was isolated by flash chromatography (silica gel,
Hetzer, H. Clausen-Schaumann, S. Bayerl, T. M. Bayerl, X. Camps, O.
Vostrowsky, A. Hirsch, Angew. Chem. 1999, 111, 2103; Angew. Chem.
Int. Ed. 1999, 38, 1962; d) F. Djojo, E. Ravanelli, A. Hirsch, O.
Vostrowsky, Eur. J. Org. Chem. 2000, 1051; e) M. Brettreich, S.
Burghardt, C. Bˆttcher, S. Bayerl, T. Bayerl, A. Hirsch, Angew. Chem.
2000, 112, 1915; Angew. Chem. Int. Ed. 2000, 39, 1845; f) M. Braun, X.
Camps, O. Vostrowsky, A. Hirsch, E. Endre˚, T. M. Bayerl, O. Birkert,
G. Gauglitz, Eur. J. Org. Chem. 2000, 1173; g) J. F. Nierengarten,
Chem. Eur. J. 2000, 6, 3667.
toluene/ethyl acetate, 24:1), washed with pentane, and dried in a vacuum.
Yield: 50 mg (0.045 mm, 32%), red brownish solid.
1H NMR (400 MHz, CDCl
3
, 258C): d ˆ 2.19 (m, 4H; CH
2
), 4.20 (t, J ˆ
6
.0 Hz, 4H; CH
arom. H), 8.30 (m, 4H; arom. H); C NMR (100 MHz, CDCl
9.96 (2C; CH
), 52.17 (1C; BkÀC), 63.35 (2C; CH
C), 72.01 (2C; OCH
2
OCˆO), 4.63 (t, J ˆ 5.9 Hz, 4H; OCH
2
), 7.44 (m, 4H;
1
3
3
, 258C): d ˆ
3
2
2
2
OCˆO), 71.10 (C60-sp -
2
), 122.75 (4C; CH), 124.52 (4C; C), 125.49 (4C; CH),
1
1
38.26, 140.74, 141.73, 142.13, 142.86, 143.01, 143.80, 144.49, 144.54, 144.65,
2
[2] a) H. Imahori, Y. Sakata, Adv. Mater. 1997, 9, 537; b) N. MartÌn, L.
S a¬ nchez, B. Illescas, I. P e¬ rez, Chem. Rev. 1998, 98, 2527; c) H. Imahori,
Y. Sakata, Eur. J. Org. Chem. 1999, 2445; d) D. M. Guldi, Chem.
Commun. 2000, 321; e) D. M. Guldi, M. Prato, Acc. Chem. Res. 2000,
44.84, 145.04, 145.18, 145.26 (C60-sp -C), 147.92 (2C; ArCÀO), 162.52 (2C;
‡
CˆO); MS (FAB): m/z (%): 1112 [M] , 720; IR (KBr): nÄ ˆ 3047, 2962, 1745,
1
7
4
617, 1461, 1428, 1405, 1348, 1264, 1227, 1204, 1187, 1096, 1060, 928, 802, 780,
À1
29, 684, 668 cm ; UV/Vis (CH
2
Cl
2
): lmax (e) ˆ 264 (176000), 326 (31000),
3
3, 695; f) S. Fukuzumi, D. M. Guldi in Electron Transfer in Chemistry,
25 (3800), 494 (1300), 580 nm (600).
Vol. 2 (Ed.: V. Balzani), Wiley-VCH, Weinheim, 2001, p. 270.
3] H. Imahori, D. M. Guldi, K. Tamaki, Y. Yoshida, C. Luo, Y. Sakata, S.
Fukuzumi, J. Am. Chem. Soc. 2001, 123, 6617.
Hexakisadduct 18: Compound 9,10-dimethylanthracene (93 mg, 0.45 mm)
was added to a solution of monoadduct 17 (50 mg, 0.045 mm) in pure
toluene (50 mL) under a nitrogen atmosphere, and the mixture was stirred
for 3 hours. Diethyl bromomalonate (107 mg, 0.45 mm) and DBU (68 mg,
[
[
4] a) N. S. Sariciftci, L. Smilowitz, A. J. Heeger, F. Wudl, Science 1992,
2
58, 1474; b) J.-F. Eckert, J.-F. Nicoud, J.-F. Nierengarten, S. G. Liu, N.
Armaroli, L. Ouali, V. Krasnikov, G. Hadziioannou, J. Am. Chem. Soc.
000, 122, 7467; c) C. Luo, D. M. Guldi, M. Maggini, E. Menna, S.
0
.45 mm) were then added. The mixture was stirred for 24 hours at room
temperature, and the course of the reaction was monitored by analytical
HPLC (nucleosil, toluene/ethyl acetate 19:1). The product was achieved by
flash chromatography with gradient elution (silica gel, toluene/ethylacetate
2
Mondini, N. A. Kotov, M. Prato, Angew. Chem. 2000, 112, 4052;
Angew. Chem. Int. Ed. 2000, 39, 3905; d) H. Imahori, H. Norieda, H.
Yamada, Y. Nishimura, I. Yamazaki, Y. Sakata, S. Fukuzumi, J. Am.
Chem. Soc. 2001, 123, 100; e) A. M. Ramos, M. T. Rispens, J. K. J.
van Duren, J. C. Hummelen, R. A. J. Janssen, J. Am. Chem. Soc. 2001,
1
9:1/9:1). It was washed with pentane and dried in a vacuum. Yield: 20 mg
0.011 mm, 23%), yellow orange solid.
1H NMR (400 MHz, CDCl
, 258C): d ˆ 1.29 (m, 30H; CH
CH ), 4.29 (m, 20H; OCH
), 3.70 (t, J ˆ 6.3 Hz, 4H; OCH
.8 Hz, 4H; OCH ), 7.47 (m, 4H; arom. H), 8.27 (m, 4H; arom. H);
(
3
3
), 1.92 (m, 4C;
), 4.52 (t, J ˆ
2
2
2
1
23, 6714.
5
2
[
[
5] L. Echegoyen, L. E. Echegoyen, Acc. Chem. Res. 1998, 31, 593.
6] a) P. J. Fagan, J. C. Calabrese, B. Malone, J. Am. Chem. Soc. 1991, 113,
1
3
C NMR (100 MHz, CDCl
3
, 258C): d ˆ 13.86, 13.96, 14.07, 14.17 (CH
3
),
),
2
6
1
1
(
2
9.43 (2C; CH
2
), 45.02, 45.26 (BkÀC), 62.61, 62.82, 63.04, 63.35 (OCH
2
9
408; b) A. Hirsch, I. Lamparth, T. Gˆsser, H. R. Karfunkel, J. Am.
3
8.73, 68.92, 68.96, 69.03 (C60-sp -C), 71.73 (2C; OCH
2
), 122.55, 122.63,
Chem. Soc. 1994, 116, 9385; c) R. Schwenniger, T. M¸ller, B. Kr‰utler,
J. Am. Chem. Soc. 1997, 119, 9317; d) L. Isaacs, F. Diederich, R. F.
Haldimann, Helv. Chim. Acta 1997, 80, 317; e) W. Qian, Y. Rubin,
Angew. Chem. 1999, 111, 2504; Angew. Chem. Int. Ed. 1999, 38, 2356;
f) G. Schick, M. Levitus, L. Kvetko, B. A. Johnson, I. Lamparth, R.
Lunkwitz, B. Ma, S. I. Khan, M. A. Garcia-Garibay, Y. Rubin, J. Am.
Chem. Soc. 1999, 121, 3246; g) C. R. Woods, J.-P. Bourgeois, P. Seiler,
F. Diederich, Angew. Chem. 2000, 112, 3971; Angew. Chem. Int. Ed.
2000, 39, 3813.
24.80, 125.44 (arom. C), 140.78, 140.96, 141.02, 141.07, 145.29, 145.61,
2
45.64, 145.68 (C60-sp -C), 147.23, (2C; ArCÀO), 162.66, 163.64, 163.75
‡
CˆO); MS (FAB): m/z (%): 1901 [M] ; IR (KBr): nÄ ˆ 3065, 2979, 2937,
À1
905, 1745, 1465, 1368, 1350, 1219, 1079, 1018, 856, 715 cm ; UV/Vis
(
3
CH
2
Cl
2
): lmax (e) ˆ 246 (113000), 264 (165000), 281 (76000), 312 (47000),
34 (37000), 386 nm (10100).
Hexakisadduct 19: Compound 9,10-dimethylanthracene (79 mg, 0.38 mm)
was added to a solution of C60 (27 mg, 0.038 mm) in pure toluene (50 mL)
under a nitrogen atmosphere, and the mixture was stirred for 3 hours.
Malonate 9 (150 mg, 0.38 mm), tetrabromomethane (126 mg, 0.38 mm), and
DBU (73 mg, 0.48 mm) were then added. The mixture was stirred for
[7] a) D. K. Smith, F. Diederich, Chem. Eur. J. 1998, 4, 1353; b) M.
Fischer, F. Vˆgtle, Angew. Chem. 1999, 111, 934; Angew. Chem. Int.
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Acc. Chem. Res. 2001, 34, 60.
[8] K. Bauer, U. Nickel, M. Diekers, A. Hirsch, unpublished results.
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107, 1755; Angew. Chem. Int. Ed. Engl. 1995, 34, 1607; b) A. Hirsch, O.
Vostrowsky, Eur. J. Org. Chem. 2001, 829.
4
8 hours at room temperature, and the course of the reaction was
monitored by TLC (nucleosil, toluene/ethyl acetate 19:1). The product
was obtained by flash chromatography (silica gel, toluene/ethylacetate
1
9
1
9:1) followed by preparative HPLC (nucleosil, dichloromethane/ethanol,
9.7:0.3). It was then washed with pentane and dried in a vacuum. Yield:
0 mg (0.003 mm, 9%), yellow solid.
1H NMR (400 MHz, C
[10] G. W. H. Cheeseman, J. Chem. Soc. 1955, 3308.
2
D
2
Cl
4
, 808C): d ˆ 1.83 (brs, 24H; CH
2
), 3.59 (brs,
), 7.48 (m, 24H; arom. H), 8.26
2
(
4H; OCCH
2
CO), 4.47 (brs, 24H; OCH
2
[11] E. P. Kyba, R. E. Davis, C. W. Hudson, A. M. John, S. B. Brown, M. J.
McPaul, L.-K. Liu, A. C. Glover, J. Am. Chem. Soc. 1981, 103, 3838.
[12] M. Diekers, A. Hirsch, C. Luo, D. M. Guldi, K. Bauer, U. Nickel, Org.
Lett. 2000, 2741.
[13] U. Seitz, J. Daub, Synthesis 1986, 686.
[14] F. Djojo, A. Herzog, I. Lamparth, F. Hampel, A. Hirsch, Chem. Eur. J.
1996, 2, 1537.
m, 24H; arom. H); 1 C NMR (100 MHz, C
3
2
D
2
Cl
4
, 808C): d ˆ 29.07 (12C;
3
CH
2
), 44.92 (6C; BkÀC), 63.54 (12C; OCCH
2
CO), 68.48 (12C; C60-sp -C),
7
1
1
2
2
1.23 (12C; OCH ), 122.35 (24C; CH), 124.75 (24C; C), 125.31 (24C; CH),
2
2
40.26 (24C; C60-sp -C), 144.60 (24C; C60-sp -C), 146.72 (12C; ArCÀO),
‡
62.11 (12C; CˆO); MS (FAB): m/z (%): 3073 [M] ; IR (KBr): nÄ ˆ 3065,
À1
959, 1745, 1618, 1406, 1349, 1263, 1212, 1053, 781, 715, 687, 665 cm ; UV/
Vis (CH
2
Cl
2
): lmax (e) ˆ 264 (198000), 370 (10200), 389 (11000), 411 (8800),
[15] a) X. Camps, E. Dietel, A. Hirsch, S. Pyo, L. Echegoyen, S. Hackbarth,
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M. Gross, L. Isaacs, H. L. Anderson, R. Faust, F. Diederich, Helv.
Chim. Acta, 1995, 78, 1334.
5
24 nm (900).
[
16] The absorption spectra of the investigated donor± acceptor ensembles
reveal the superimposed features of the individual components.
17] D. M. Guldi, K.-D. Asmus, J. Phys. Chem. A 1997, 101, 1472.
18] The fluorescence decay curves, which were well fitted by a single
exponential decay component, further corroborate the steady-state
experiments. Table 1 lists the respective fluorescence lifetimes in
solvents of different polarity.
Acknowledgements
[
[
Part of this work was supported by the Office of Basic Energy Sciences of
the US Department of Energy. This is document NDRL-XXXX from the
Notre Dame Radiation Laboratory. We thank the Deutsche Forschungs-
gemeinschaft (DFG) and the Stiftung Volkswagenwerk for financial
support.
[
[
19] S. L. Murov, I. Carmichael, G. L. Hug, Handbookof Photochemistry ,
Marcel Dekker, New York, 1993.
20] Pulse radiolytic reduction with T -C66(COOEt) was performed in
h 2
[
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entity.
990
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0804-0990 $ 17.50+.50/0
Chem. Eur. J. 2002, 8, No. 4

T -Symmetrical Hexakisadducts of C
h
979±991
60
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1
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Received: July 3, 2001 [F3388]
Chem. Eur. J. 2002, 8, No. 4
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
0947-6539/02/0804-0991 $ 17.50+.50/0
991