Synthesis and properties of bingel-type methanofullerene - π-extended-TTF diads and triads

Article abstract of DOI:10.1021/jo020412l

Novel C₆₀/π-extended tetrathiafulvalene (exTTF) diads (12a-c) and triads [D₂A (14a-c) and DA₂ (25, 27a-c)] have been synthesized by the Bingel cyclopropanation reaction of the respective exTTF-containing malonates and [60]fullerene. The reaction of exTTF-bismalonates with C₆₀ affords the respective C₆₀-exTTF diads (26a-c) together with the triad C₆₀-exTTF-C₆₀ (25, 27a-c) and a regioisomeric mixture of bisadducts (28b-c). Theoretical calculations (PM3) predict the favored geometry for triads 14a-c depending upon the orientation (up and down) of the 1,3-dithiole rings in the exTTFs, as well as the more stable regioisomers for the bisadducts 28. Cyclic voltammetry measurements reveal that C₆₀ and exTTF units do not intereact in the ground state. Compounds 26a-c and 27a-c are not electrochemically stable. A photoinduced electron transfer leading to the formation of the radical pair (C₆₀^--exTTF^?+) has been observed for compounds 14a-c.

Full text of DOI:10.1021/jo020412l

Syn th esis a n d P r op er ties of Bin gel-typ e
Meth a n ofu ller en e-π-Exten d ed -TTF Dia d s a n d Tr ia d s
Susana Gonza´lez and Nazario Mart´ın*
Departamento de Quı´mica Orga´nica, Facultad de Ciencias Qu´ımicas, Universidad Complutense,
E-28040-Madrid, Spain
Dirk M. Guldi*
Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556
nazmar@quim.ucm.es
Received J une 14, 2002
Novel C60/π-extended tetrathiafulvalene (exTTF) diads (12a -c) and triads [D2A (14a -c) and DA2
(25, 27a -c)] have been synthesized by the Bingel cyclopropanation reaction of the respective exTTF-
containing malonates and [60]fullerene. The reaction of exTTF-bismalonates with C60 affords the
respective C60-exTTF diads (26a -c) together with the triad C60-exTTF-C60 (25, 27a -c) and a
regioisomeric mixture of bisadducts (28b-c). Theoretical calculations (PM3) predict the favored
geometry for triads 14a -c depending upon the orientation (up and down) of the 1,3-dithiole rings
in the exTTFs, as well as the more stable regioisomers for the bisadducts 28. Cyclic voltammetry
measurements reveal that C60 and exTTF units do not intereact in the ground state. Compounds
26a -c and 27a -c are not electrochemically stable. A photoinduced electron transfer leading to
the formation of the radical pair (C60--exTTF•+) has been observed for compounds 14a -c.
In tr od u ction
attributed to the small reorganization energy of C60 in
electron-transfer reactions as well as to the gain of
aromaticity undergone by the TTF and exTTF moieties
upon oxidation. Both factors are believed to be respon-
sible for the generation of stable radical pairs that show
lifetimes in the range of nanoseconds for C60-TTF 2 and
several hundred of nanoseconds for the analogous C60-
exTTFs diads.3
On account of the outstanding lifetimes measured in
C60-exTTF diads, we have pursued the design of C60-
exTTF ensembles, in which the donor unit (exTTF) was
covalently attached to the C60 core via cycloaddition
reactions. To this end, fulleropyrrolidines (1a -c, 2a -c)3a
prepared by 1,3-dipolar cycloaddition reaction of “in situ”
generated azomethyne ylides to C60,4 Diels-Alder cy-
cloadducts 3a -c obtained by cycloaddition of “in situ”
generated heterocyclic o-quinodimethanes to C60,3b and
cycloaddition of “in situ” generated diazo compounds to
C60 to form methanofullerenes 4a -c by nitrogen extru-
sion3c have been recently reported. In all these systems
(1-4), the synthetic approaches afforded the correspond-
ing C60-exTTF diads with a 1:1 donor:acceptor stoichi-
ometry (Chart 1).
The prominent features of fullerenes as electron ac-
ceptors and their versatilitysespecially in the excited
statessled to the development of a wide variety of
electroactive C60-based donor-acceptor systems, espe-
cially light-induced charge-separation in artificial pho-
tosynthetic systems and photovoltaic devices.1
Among the different electron donor molecules co-
valently attached to [60]fullerene, tetrathiafulvalene
(TTF),2 and particularly π-extended tetrathiafulvalene
(exTTF)3 have been successfully used in the preparation
of C60-based diads that, upon radiation, form long-lived
charge-separated states. The interesting photophysical
behavior of C60-TTF and C60-exTTF diads has been
* Corresponding author. Fax: +34 91 3944103.
(1) (a) Imahori, H.; Sakata, Y. Adv. Mater. 1997, 9, 537. (b) Mart´ın,
N.; Sa´nchez, L.; Illescas B.; Pe´rez, I. Chem. Rev. 1998, 98, 2527. (c)
Imahori, H.; Sakata, Eur. J . Org. Chem. 1999, 2445. (d) Guldi, D. M.
Chem. Commun. 2000, 321. (e) Guldi, D. M.; Prato, M. Acc. Chem. Res.
2000, 33, 695. (f) Gust, D.; Moore, T. A.; Moore, A. J . Acc. Chem. Res.
2001, 34, 40. (g) Guldi, D. M. Chem. Soc. Rev, 2002, 31, 22.
(2) (a) Mart´ın, N.; Sa´nchez, L.; Seoane, C.; Andreu, R.; Gar´ın, J .;
Orduna, J . Tetrahedron Lett. 1996, 37, 5979. (b) Prato, M.; Maggini,
M.; Giacometti, C.; Scorrano, G. M; Sandona´, G.; Farnia, G. Tetrahe-
dron 1996, 52, 5221. (c) Boulle, C.; Cariou, M.; Bainville, M.; Gorgues,
A.; Hudhomme, P.; Orduna, J .; Gar´ın, J . Tetrahedron Lett. 1997, 38,
81. (d) Boulle, C.; Rabreau, J . M.; Hudhomme, P.; Cariou, M.; J ubault,
M.; Gorgues, A.; Orduna, J .; Gar´ın, J . Tetrahedron Lett. 1997, 38, 3909.
(e) Llacay, J .; Mas, M.; Molins, E.; Veciana, J .; Powell, D.; Rovira, C.
Chem. Commun. 1997, 659. (f) Hudhomme, P.; Boulle, C.; Rabreau, J .
M.; Cariou, M.; J ubault, M.; Gorgues, A. Synth. Met. 1998, 94, 73. (g)
Mart´ın, N; Sa´nchez, L; Herranz, M. A.; Guldi, D. M. J . Phys. Chem. A
2000, 104, 4648. (h) Guldi, D. M.; Gonza´lez, S.; Mart´ın, N.; Anto´n, A.;
Gar´ın, J .; Orduna, J . J . Org. Chem. 2000, 65, 1978.
With the objective to achieve C60-exTTF ensembles
with D:A stoichiometries other than 1:1 (i.e., 2:1 and 1:2),
we wish to report in this paper the synthesis of different
diads and triads via employing the highly versatile Bingel
reaction.5 This cyclopropanation reaction of C60 leads
efficiently to methanofullerenes. The reaction proceeds
by addition of a stable R-halocarbanion to C60, followed
(3) (a) Mart´ın, N.; Pe´rez, I.; Sa´nchez, L.; Seoane, C. J . Org. Chem.
1997, 62, 5690. (b) Herranz, M. A.; Mart´ın, N. Org. Lett, 1999, 1, 2005.
(c) Mart´ın, N.; Sa´nchez, L.; Guldi, D. M. Chem. Commun. 2000, 113.
(4) Prato, M.; Maggini, M. Acc. Chem. Res. 1998, 31, 519.
(5) Bingel, C. Chem. Ber. 1993, 126, 1957.
10.1021/jo020412l CCC: $25.00 © 2003 American Chemical Society
Published on Web 12/28/2002
J . Org. Chem. 2003, 68, 779-791
779

Gonza´lez et al.
CHART 1
Resu lts a n d Discu ssion
Syn t h esis of Dia d s a n d Tr ia d s (exTTF -C60
-
exTTF ). Diads C60-exTTF (12a -c) were prepared in a
multistep synthetic procedure, starting with commer-
cially available 2-hydroxymethyl-9,10-anthraquinone (5).
An outline is depicted in Scheme 1. After protection of
the hydroxy group in 5 with tertbutyldiphenylsilyl in
DMF and in the presence of imidazole, compound 6 was
obtained in 89% yield. Then, the introduction of the 1,3-
dithiole rings in 6 was carried out by the Wittig-Horner
olefination reaction with the corresponding phosphonates
(7a -c), which were, in turn, prepared by following the
method previously reported.10 Protected exTTFs (8a -c)
were obtained in good yields (85-95%) by using an excess
of phosphonate (1:4), favoring the formation of the bis-
condensed compounds 8a -c. Further treatment of 8a -c
with tetrabutylammonium fluoride in THF at room
temperature afforded the 2-hydroxymethyl-substituted
exTTFs (9a -c) in very good yields (90-97%).
Compounds 9a -c are interesting electron-donor build-
ing blocks, especially for the preparation of salts and
charge-transfer complexes, since, in addition to their
strong electron-donor character, they bear hydroxy groups.
The latter form networks of hydrogen bonds with refined
dimensionality in the solid state. The importance of
hydrogen bonds in TTF derivatives to gain control over
crystal architectures has been reviewed by Bryce.11
Furthermore, exTTFs 9a -c are suitably functionalized
for chemical transformations.
by an intramolecular nucleophilic substitution of the
halide by the carbanion generated on the C60 surface. It
has also been shown that the cyclopropanation reaction
can take place directly from malonates in the presence
6
7
of I2 or CBr4 and even a base.
Thus, we carried out the esterification reaction of 9a -c
with equimolar amounts of ethoxycarbonylacetic acid
chloride in CH2Cl2 at 0 °C under argon atmosphere in
the presence of pyridine. The corresponding compounds
10a -c were formed in almost quantitative yields. Only
compound 10c was obtained in a lower yield (77%), as a
consequence of the lower solubility of 9c in the reaction
medium. Compounds 10a -c, similarly to their precur-
sors, were obtained as yellow solids that were purified
by column chromatography. All the compounds were
characterized by analytical and spectroscopic methods
(UV-vis, FTIR, 1H and 13C NMR, and MS) (see the
Experimental Section).
Diads 12a -c were prepared from 10a -c by following
two different procedures. The first route involves reaction
of 10a with CBr4 and DBU in THF at -78 °C, which
afforded the bromo derivative 11a in moderate yields
(40%). Further treatment of 11a with sodium hydride in
toluene, followed by processing with sulfuric acid, led to
diad 12a in a low yield (11%). Alternatively, diads 12a -c
were obtained with better yields (18-27%) and in shorter
times (1.5-2h) by direct reaction of 10a -c with C60 and
CBr4/DBU in toluene. They were purified by column
chromatographysfirst hexane to remove unreacted C60
and then toluene/chloroform 1:1 to isolate 12a -c as
greenwish solidssand centrifugation with hexane, metha-
nol, and diethyl ether.
An important asset of the cyclopropanation reaction
is that upon electrochemical reduction the removal of the
cyclopropane ring adduct results in the formation of the
parent C60.8 Addend removal via electrolytic reduction
is, however, not only limited to Bingel-type adducts but
also occurs for non-Bingel methanofullerenes.9
Therefore, we have carried out the synthesis of novel
C60-exTTF (12a -c, 26a -c, 28a -c) diads as well as C60-
(exTTF)2 (14a -c) and (C60)2-exTTF (25, 27a -c) triads
by using the cyclopropanation Bingel reaction of suitably
functionalyzed malonates and [60]fullerene. The redox
properties of the new compounds were determined by
cyclic voltammetry at room temperature, and semiem-
pirical (PM3) theoretical calculations were performed to
gain a better understanding of the geometric and elec-
tronic properties of the prepared systems.
Finally, photophysical measurements (fluorescence and
transient absorption spectra) have been carried out to
complement the present study.
(6) (a) Nierengarten, J .-F.; Gramlich, V.; Cardullo, F.; Diederich, F.
Angew. Chem., Int. Ed. Engl. 1996, 35, 2101. (b) Nierengarten, J .-F.;
Herrmann, A.; Tykwinsk, R. R.; Ru¨ttimann, M.; Diederich, F.; Boudon,
C.; Gisselbrecht, J .-P.; Gross, M. Helv. Chim. Acta 1997, 80, 293.
(7) Camps, X.; Hirsch, A. J . Chem. Soc., Perkin Trans. 1 1997, 1595.
(8) (a) Kessinger, R.; Crassous, J .; Herrmann, A.; Ru¨ttimann, M.;
Echegoyen, L.; Diederich, F. Angew. Chem. Ed. Int. Engl. 1998, 37,
1919. (b) Kessinger, R.; Fender, N. S.; Echegoyen, L. E.; Thilgen, C.;
Echegoyen, L.; Diederich, F. Chem. Eur. J . 2000, 6, 2184.
(9) (a) Beulen, M. W. J .; Echegoyen, L.; Rivera, J . A.; Herranz, M.
A.; Mart´ın-Domenech, A.; Mart´ın, N. Chem. Commun. 2000, 917. (b)
Beulen, M. W. J .; Rivera, J . A.; Herranz, M. A.; Mart´ın-Domenech, A.;
Mart´ın, N.; Echegoyen, L. Chem. Commun. 2001, 407. (c) Beulen, M.
W. J .; Rivera, J . A.; Herranz, M. A.; Illescas, B.; Martı´n, N.; Echegoyen,
L. J . Org. Chem. 2001, 66, 4393; Herranz, M. A.; Beulen, M. W. J .;
Rivera, J . A.; Echegoyen, L.; D´ıaz, M. C.; Illescas, B. M.; Mart´ın, N. J .
Mater. Chem. 2002, 12, 2048.
Compounds 12a -c have absorption maxima at 436-
454 nm due to the presence of the exTTF moiety. The
13C NMR spectra showed the presence of the fullerene
sp3 carbons at δ ∼ 77.2 and 71.2, thus confirming the
(10) Bryce, M. R.; Moore, A. J . Synthesis 1991, 26.
(11) Bryce, M. R. J . Mater. Chem. 1995, 5, 1481.
780 J . Org. Chem., Vol. 68, No. 3, 2003

Bingel-type C60/ exTTF Diads and Triads
SCHEME 1
closed [6,6] nature of the fullerene unit. The MS (positive
APCI) data (12a , m/z 1244; 12b, m/z 1428; 12c, m/z 1424)
also confirmed the proposed structures.
11 Hz) for 14c in which one of the doublets is not clearly
observed due to the low solubility of this compound.
Compound 14b, which exhibited a good solubility, showed
the -CH2O- protons as two well-defined AB systems.
Dimeric exTTF (13a -c) were prepared in 35-57%
yields from 9a -c by reaction with malonic acid dichloride
in CH2Cl2 at 0 °C by using an excess of alcohol. These
malonate derivatives, endowed with two exTTF units
(13a -c), were reacted with C60 and DBU/CBr4 in toluene
to form the respective Bingel adducts in moderate yields
(16-25%, 60-70% yield based on the recovered C60).
The structure of triads 14a -c was determined on the
1
In addition, we carried out H NMR studies at different
temperatures in deuterated toluene to determine the
coalescence temperature (20 °C) of these protons for the
most soluble compound, 14b. At room temperature the
two doublets of the AB system coalescence into two
singlets. Upon increasing the temperature to 29 °C, the
other two doublets appear as two separate singlets. These
low coalescence temperatures are responsible for the
different behavior seen for the -CH2O- protons in 14a -
c. On the other hand, the presence of the two -CH2O-
groups in 14a -c as two different AB systems can be
explained by the presence of different rotational isomers.
1
basis of their spectroscopic data: UV-vis, FTIR, H and
13C NMR, and MS. Similar to what was found for diads
12a -c, the 1H NMR spectra of triads 14a -c showed
anisochronous protons for the -CH2O- group. Thus, the
-CH2O- protons in 14a appear as broad singlets at δ )
5.53, while they are only observed as an AB system (J )
J . Org. Chem, Vol. 68, No. 3, 2003 781

Gonza´lez et al.
F IGURE 1. Different isomers (A-D) expected for 14a depending on the relative orientation of the 1,3-dithiole rings (up or down).
Calculations predict A as the favored isomer.
The latter effect is due to the flexibility of the spacer,
connecting the exTTF and C60 units.
of the angle R, formed by the “wings of the butterfly”
(dihedral angle C2-C1-C4-C5), and the angle γ, which
defines the tilting of the 1,3-dithiole rings with respect
to the C2-C3-C5-C6 plane (dihedral angle C7-C2-
C6-C5). R and γ have values of 144.3° and 34.6°,
respectively.
To determine the favored geometry of triads 14a -c as
1
well as to confirm the H NMR observations, we carried
out theoretical calculations with compound 14a at the
semiempirical PM3 (Hyperchem 5.0) level.
These values are in good agreement with X-ray data
(γ ) 34.9°)12 for the parent exTTF unit and with earlier
calculations.13 Most importantly, the theoretical data
indicate the lack of interaction between the donor (exT-
TF) and acceptor (C60) units in the ground state, which
agrees with the distance (6.63 Å) found between the
sulfur atom and C60 in the most favored conformation A
(Figure 1). This prediction also supports the UV-vis data,
which did not show the presence of a low-energy charge-
transfer band from the HOMO (-7.99 eV)slocalized on
the π-extended TTF donor moietysto the LUMO (-2.80
eV) of the C60 acceptor unit.
Depending on the relative orientation of the 1,3-
dithiole rings in 14a , namely, up or down, different
isomers are expected (Figure 1). Our calculations predict
A as the favored isomer. The latter is, however, only 0.28
kcal/mol more stable than the rotational isomer B. Larger
enthalpy differences were found with isomers C (2.37
kcal/mol) and D (3.34 kcal/mol). Both isomers bear the
1,3-dithiole rings of one and two extended-TTF units,
respectively, pointing to the C60 surface.
In summary, the small enthalpy difference between
isomers, as well as the existence of rotational isomers
due to the σ-bonds present in the connectivity of the
exTTF unit to the C60 core account for the low coalescence
Notably, the most significant changes are created on
C60, due to the presence of the fused cyclopopane ring.
Thus, the bond length predicted between C1 and C2
1
temperatures seen in the H NMR spectra.
Clearly, the theoretical calculations show the highly
distorted geometry of the exTTF moiety. This is due to
the strong steric interaction between the sulfur atoms
of the 1,3-dithiole rings and the CH units in adjacent peri
positions, forcing a butterfly-shaped structure. The dis-
tortion from planarity can be best described as a function
(12) Bryce, M. R.; Coffin, M. A.; Hursthouse, M. B.; Karaulov, A. I.;
Mu¨llen, K.; Schiech, H. Tetrahedron Lett. 1991, 32, 6029.
(13) (a) Mart´ın, N.; Sa´nchez, L.; Seoane, C.; Ort´ı, E.; Viruela, P. M.;
Viruela, R. J . Org. Chem. 1998, 63, 1268. (b) Mart´ın, N.; Pe´rez, I.;
Sa´nchez, L.; Seoane, C. J . Org. Chem. 1997, 62, 5690.
782 J . Org. Chem., Vol. 68, No. 3, 2003

Bingel-type C60/ exTTF Diads and Triads
(1.548 Å) is 0.164 Å larger than that reported for the [6,6]
bond in the parent C60, and slighly shorter than that
measured for the related bis(trimethylsilylbutadiinyl)-
methanofullerene (1.574 Å)14 and (3,4-dimethoxyphenyl)-
methanofullerene (1.614 Å).15
Syn th esis of Dia d s a n d Tr ia d s (C60-exTTF -C60).
The preparation of C60/exTTF ensembles with a different
stoichiometry (C60-exTTF-C60) requires the use of bis-
functionalized exTTFs. In this regard, bis-hydroxy func-
tionalized exTTFs are readily available from anthraflavic
acid (2,6-dihydroxy-9,10-anthraquinone, 15), as outlined
in Scheme 2.
The synthesis of the respective hydroxy-functionalized
exTTFs (21 and 22a -c) requires protection of the hy-
droxy groups of anthraflavic acid (15) and 2,6-bis(2-
hydroxyethyloxy)-9,10-anthraquinone (17), which was
obtained from 15 by treatment with 2-bromoethanol
under basic conditions. Further treatment of 15 and 17
with tertbutyldiphenylsilyl chloride afforded the hydroxy-
protected compounds 16 and 18, respectively, in good
yields. Introduction of the 1,3-dithiole rings in quinones
16 and 18 was carried out by reaction with phosphonates
7a -c in the presence of butyllithium at -78 °C, similarly
to that reported above for compounds 8a -c. It is worth
mentioning that better yields (75-85%) were obtained
when a quinone:phosphonate (1:6) stoichiometry was
used.
Protecting groups were easily removed from 19 and
20a -c by treatment with tetrabutylammonium fluoride
in THF at room temperature, yielding the respective
exTTF donors 2116 and 22a -c as stable solids. The UV-
vis spectra of these compounds showed an intense
absorption band at around 430 nm.
The introduction of the malonate moiety, needed for
the covalent linkage to the C60 sphere, was carried out
by reaction of 21 and 22a -c with ethoxycarbonylacetyl
chloride. Thus, compounds 23 and 24a -c, endowed with
two malonate moieties, respectively, were obtained in
good yields (58-70%).
To favor the formation of triads, a 6-fold excess of C60
was used in the reaction with malonates. Under these
conditions, triad 25 was obtained from 23 in only 8%
1
yield. The H and 13C NMR spectra showed a symmetric
molecule with only a bridgehead carbon atom at ∼51-
52 ppm, corresponding to the cyclopropane ring.
Reaction of 24a -c with an excess (6:1) of C60 afforded,
similarly to 25, triads 27a -c, which were obtained in
moderate yields (12-15%), together with other noniso-
lated compounds that were obtained in trace amounts.
A different result was obtained when a different
stoichiometry of reagents (24:C60, 1:1) was used, under
the same reaction conditions (i.e., DBU, o-DCB, 0 °C).
The outcome of the reaction, namely, the formation of
three different organofullerenes (26-28), is summarized
in Scheme 2.
The main reaction product diads 26a -c were obtained
in moderate yields (12-22%), together with a regioiso-
meric mixture of bis-addition products (28a -c) (6-8%).
Isolation of the products, obtained from the reaction of
24a -c with C60, was carried out by column chromatog-
raphy (silica gel). Unreacted C60 was eluted with a
toluene:ethyl acetate (50:1) mixture. Further purification
was accomplished by centrifugation in hexane, methanol,
and diethyl ether.
A second intramolecular Bingel reaction in 26a -c
brings about diads 28b,c. In fact, TLC showed increasing
yields of 28 simultaneously with decreasing yields in
26a -c. Although observed by TLC, compound 28a could
not be isolated and, therefore, its precursor 26a was
obtained in much higher yield (22%) than the related
analogues (26b,c; 12-13%).
Finally, despite the 1:1 stoichiometry used, triads
27a -c were low-yield byproducts (∼1%), which were
characterized by comparison with authentic samples.
It is worth mentioning that the different behavior of
bis-malonates 23 and 24a -c in the reaction with C60
under Bingel conditions stems from the chain length
connecting the malonate moieties and the central exTTF.
Thus, the presence of two conformationally flexible
-OCH2CH2O- groups in 26a -c allows a subsequent
intramolecular Bingel reaction, affording compounds
28b,c.
Compounds 23 and 24a -c, as well as their precursors,
1
were characterized by UV-vis, FTIR, H and 13C NMR,
and MS. It is worth mentioning that, in addition to the
expected aromatic and -CH2O- signals, the active
methylene groups of the malonate moieties were observed
in all cases as singlets involving four protons at 3.65 ppm
Recently, tether-directed bis-cycloadducts forming
cyclophane-type electroactive diads bearing porphyrins
as donor moieties have been skillfully synthesized.17
Photophysical studies carried out with some of these
C60-porphyrin donor-acceptor diads have disclosed
one of the first experimental confirmations that back-
electron-transfer from the one-electron-oxidized por-
phyrin to the radical anion of C60 is placed deeply into
the Marcus inverted region.18 Similarly, an o-phenylene-
diamine has been also used as donor unit in this type of
bis-cycloadduct.19
1
for 23 and ∼3.45 ppm for 24a -c in the H NMR spectra.
The synthesis of the C60-based triads (C60-exTTF-C60)
(25 and 27a -c) was carried out by reacting the respective
bismalonates (23 and 24a -c) with C60 (2:1 stoichiome-
try), using DBU and CBr4 in o-DCB at 0 °C. Formation
of bismethanofullerenes was observed even after short
reaction times (i.e., 15-30 min). Attempts to carry out
the reaction in toluene at room temperature, as reported
in the literature for related systems,17 led to a very fast
reaction, including the formation of undesired byprod-
ucts. It was, however, impossible to isolate the interme-
diate monoadduct from the reaction mixture.
Com p ou n d s 28b ,c were characterized on the basis of
their spectroscopic data. The FTIR spectra showed, in
(17) (a) Bourgeois, J .-P.; Diederich, F.; Echegoyen, L.; Nierengarten,
J . F. Helv. Chim. Acta 1998, 81, 1835. (b) Dietil, E.; Hirsch, A.;
Eichhorn, E.; Rieker, A.; Hackbarth, S.; Roder, B. Chem. Commun.
1998, 1981. (c) Armaroli, N.; Marconi, G.; Echegoyen, L.; Bourgeois,
J .-P.; Diederich, F. Chem. Eur. J . 2000, 6, 1629.
(18) Guldi, D. M.; Luo, C.; Prato, M.; Dietil, E.; Hirsch, A. Chem.
Commun. 2000, 373.
(14) Anderson, H.; Boudon, C.; Diederich, F.; Gisselbrecht, J . P.;
Gross, M.; Seiler, P. Angew. Chem., Int. Ed. Engl. 1994, 33, 1628.
(15) Osterodt, J .; Nieger, M.; Vo¨gtle, F. J . Chem. Soc. Chem.
Commun. 1994, 1607.
(16) (a) Marshallsay, G. J .; Bryce, M. R. J . Org. Chem. 1994, 59,
6847. (b) Marshallsay, G. J .; Hansen, T. K.; Moore, A. J .; Bryce, M.
R.; Becher, J . Synthesis 1994, 926.
(19) Diekers, M.; Hirsch, A.; Luo, C.; Guldi, D. M.; Bauer, K.; Nickel,
U. Org. Lett. 2000, 2, 2741.
J . Org. Chem, Vol. 68, No. 3, 2003 783

Gonza´lez et al.
SCHEME 2
addition to the presence of the carbonyl groups, a low-
intensity band at 526 cm-1, thus confirming the bis-
addition pattern. Although the MS confirmed the pro-
posed structures, the 1H NMR spectra showed overlapping
784 J . Org. Chem., Vol. 68, No. 3, 2003

Bingel-type C60/ exTTF Diads and Triads
multiplets, which suggests the presence of different
isomers. The different possible regioisomers (trans-1,
trans-2, trans-3, e) formed in compounds 28b,c and the
presence of two stereogenic bridgehead carbons in the
two cyclopropane rings, as well as the possible (up and
down) conformers resulting from the different orientation
of the two 1,3-dithiole rings in the exTTF unit, can
1
account for the observed complex H NMR spectra.
Theoretical calculations at the semiempirical PM3 level
(Hyperchem 5,0) were carried out on 28a (R ) H) in order
to determine the minimum energy structure. According
to the size and structure of the bis-malonate precursor
(24a ), formation of the trans regioisomers should occur
preferentially.20 In fact, among the different calculated
structures (i.e., trans-4, trans-3, trans-2, trans-1, e, cis-
3, cis-2, and cis-1), the trans-3 and cis-3 regioisomers had
the most favored geometries, being around 0.5 kcal/mol
more stable than the e isomer (Figure 2) and around 26
kcal/mol for the most unstable cis-1. For these regioiso-
mers (cis-3, trans-3, and e), the exTTF moiety shows the
1,3-dithiole rings pointing away from the fullerene
surface with a distance of 5-7 Å, which is too long for
the existence of a through space intramolecular electron
transfer in the ground state.
It is important to note that regioselectivity in bisad-
dition reactions may be governed by a kinetic control, as
there are only small differences in the thermodynamic
stability of the calculated regioisomers.
Triads (C60-exTTF-C60) were characterized by a va-
riety of spectroscopic techniques, that is, UV-vis, FTIR,
1H and 13C NMR, and MS. The UV-Vis spectra showed
intense transitions around 430 nm, stemming from the
exTTF unit, which is responsible for the yellow color of
compounds 27a -c in toluene or o-DCB solutions. This
intense band prevented the observation of the weak band
at around 430 nm typical for 1,2-dihydrofullerenes.
1
In the H NMR spectra of compounds 25 and 27a -c,
equivalent sets of protonssdue to molecular symmetrys
confirm the presence of two C60 units. The 13C NMR
spectra, on the other hand, clearly showed the presence
of the bridgehead carbon atom of the cyclopropane rings
as a single signal at ∼51-52 ppm as well as the fullerene
sp3 carbon atoms at around 77 and 71 ppm (Figure 3).
Furthermore, the structures were confirmed by mass
spectroscopy. In addition to the molecular ions, as the
most intense peaks, peaks were recorded that correspond
to the loss of a fullerene unit (M+ - C60) for 27a ,b.
Compound 25 presented the peaks corresponding to the
loss of one (1542, M+ - C60) and two (822, M+ - 2C60)
fullerene units.
Electr och em istr y. The redox properties (Table 1) of
the diads and triads have been studied by cyclic volta-
mmetry (CV) at room temperature in toluene:acetonitrile
(4:1) as solvent, along with those of C60 and the parent
π-extended 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroan-
thracene (29).12,21
F IGURE 2. Theoretical calculations at the semiempirical
PM3 level (Hyperchem 5,0) for 28a predict the trans-3, cis-3,
and e regioisomers as the most favored structures.
(20) (a) Hirsch, A.; Lamphart, I.; Karfuakel, M. R. Angew. Chem.,
Int. Ed. Engl. 1994, 32, 437. (b) Hirsch, A.; Lamparth, I.; Schicck, G.
Liebigs Ann. 1996, 1725. (c) Djojo, D.; Hirsch, A. Chem. Eur. J . 1998,
4, 344.
(21) (a) Yamashita, Y.; Kobayashi, Y.; Miyashi, T. Angew. Chem.,
Int. Ed. Engl. 1998, 28, 1052. (b) Bryce, M. R.; Moore, A. J .; Hasan,
M.; Ashwell, G. J .; Fraser, A. T.; Clegg, W.; Hursthouse, M. B.;
Karaulov, A. I. Angew. Chem., Int. Ed. Engl. 1990, 29, 1450.
Clearly, the redox potential values show that substitu-
tion (mono- or bis-addition) on the C60 surface modifies
the electron-accepting properties of the C60 unit. Thus,
J . Org. Chem, Vol. 68, No. 3, 2003 785

Gonza´lez et al.
F IGURE 3. 13C NMR spectrum of triad 27b.
TABLE 1. Red ox P oten tia ls of th e New Dia d s a n d
Tr ia d s (V vs SCE)a
quasireversible behavior of the oxidation potential for
π-extended TTF had been previously confirmed by Cou-
lometric analysis23 and other studies.24 Only very re-
cently, the π-radical cation of different quinonoid π-ex-
tended TTFs have been generated and characterized by
means of time-resolved and steady-state radiation chemi-
cal techniques. These studies clearly revealed that the
instability of the π-radical cation is governed by the
disproportionation reaction of the π-radical cation into
the corresponding dications.25
Triads 14a -c bearing two exTTF units exhibit the
same redox potential values as diads 12a -c bearing only
one exTTF unit, which indicates that both exTTF units
in 14a -c behave independently and, therefore, they
present similar values as those of diads 12a -c.
The electrochemical study of compounds derived from
anthraflavic acid (26-28) was carried out on 26b-28b
(R ) SMe), due to their better solubility in the solvent
mixture. Surprisingly, the cyclic voltammogram of diad
26b showed, in addition to the expected redox peaks at
-0.65, -1.08, and -1.57 eV (see Table 1), the presence
of additional reduction waves that clearly correspond to
the reduction waves of the intramolecular bis-cycloadduct
28b. Diads 28b exhibits three reduction waves, signifi-
cantly shifted to more negative values (-0.78, -1.23,
-1.80 eV), which indicates the saturation of a second
double bond of the C60 core, raising the LUMO energy
even more.
The electrochemical formation of 28b under the CV
recording conditions of 26b cannot be ruled out. Further-
more, the voltammogram of triad 27b also showed, in
addition to the expected oxidation and reduction waves
(Table 1), the presence of other reduction waves corre-
sponding to diad 28b. Although formation of 28b from
26b is not straightforward, it has been clearly established
for other related Bingel cycloadducts that a retro-cyclo-
propanation reaction (retro-Bingel reaction) under elec-
trochemical8 and chemical26 reduction conditions can take
b
compd
E1
E1
E2
E3
E4
red
ox
red
red
red
12a
12b
12c
14a
14b
14c
26b
0.50
0.66
0.67
0.45
0.67
0.63
0.55
-0.63
-0.65
-0.63
-0.62
-0.64
-0.67
-0.65
(-0.79)c
-0.67
(-0.75)c
-0.78
-0.60
-0.99
-1.03
-1.02
-0.98
-1.04
-1.00
-1.08
(-1.22)c
-1.02
(-1.24)c
-1.23
-1.07
-1.58
-1.55
-1.52
-1.50
-1.54
-1.53
-1.57
(-1.70)c
-1.52
(-1.66)c
-1.80
-1.64
-1.72
-1.70
-1.69
-1.74
27b
0.60
0.55
0.45
28b
C60
29d
a
In toluene:MeCN (4:1); BuNClO4 as supporting electrolyte;
scan rate 200 mV/s. b Reduction of the organic addend. c Reduction
d
peaks corresponding to the bis-cycloadduct 28b. In CH2Cl2.
three quasireversible reduction wavesscorresponding to
the first three reduction steps of the fullerene moietys
are observed in the voltammograms, similarly to that
found for the parent C60 molecule. These reduction
potentials appear, however, at slightly more negative
values than those of C60. This has been accounted for by
the saturation of a double bond in the C60 framework,
which raises the LUMO energy of the resulting modified
fullerene.22 In addition, another quasireversible reduction
wave was observed at around -1.70 V in compounds
12b,c and 14b,c, which does not correspond to the
fullerene core and, therefore, could be reasonably as-
signed to the reduction of the organic addend. In the
remaining compounds 26-28, this wave is apparently
buried under the third reduction wave of the C60 core.
All compounds found in the oxidative scan showed a
two-electron quasireversible oxidation wave to form the
dication species of the exTTF moiety. As is shown in
Table 1, substitution on the 1,3-dithiole rings with R )
SMe, (SCH2)2 groups leads to an anodic shift of the
oxidation potentials, which is in agreement with that
observed for the parent molecule 29 and other related
systems.12,13,21 The two-electron nature as well as the
(23) Bryce, M. R.; Moore, A. J . J . Chem. Soc., Perkin Trans. 1 1991,
157.
(24) (a) Mart´ın, N.; Ort´ı, E. In Handbook of Advanced Electronic
and Photonic Materials and Devices; Nalwa, H. S., Ed.; Academic
Press: New York, 2001; Vol. 3, Chapter 6. (b) Pe´rez, I.; Liu, S.-G.;
Mart´ın, N.; Eghegoyen, L. J . Org. Chem. 2000, 65, 3796.
(25) (a) Guldi, D. M.; Sa´nchez, L.; Mart´ın, N. J . Phys. Chem. B 2001,
105, 7139. (b) J ones, A. E.; Christensen, C. A.; Perepichka, D. F.;
Batsanov, A. S.; Beeby, A.; Low, P. J .; Bryce, M. R.; Parker, A. W.
Chem. Eur. J . 2001, 7, 973.
(22) (a) Suzuki, T.; Maruyama, Y.; Akasaba, T.; Ando, W.; Koba-
yashi, K.; Nagase, S. J . Am. Chem. Soc. 1994, 116, 1359. (b) Chlis-
tunoff, J .; Cliffel, D.; Bard, A. J . In Handbook of Organic Conductive
Molecules and Polymers; Nalwa, H. S., Ed.; J ohn Wiley & Sons, Ltd.:
New York, 1997; Vol 1, Chapter 7. (c) Echegoyen, L.; Echegoyen, L. E.
Acc. Chem. Res. 1998, 31, 593.
786 J . Org. Chem., Vol. 68, No. 3, 2003

Bingel-type C60/ exTTF Diads and Triads
TABLE 2. P h otop h ysica l P a r a m eter s of Dia d s 12a ,c a n d Tr ia d s 14a -b
12a
12c
14a
14b
Φfluorescence
τ
singlet, ps
Φfluorescence
τ
singlet, ps
Φfluorescence
τ
singlet, ps
Φfluorescence
τ
singlet, ps
toluene
benzonitrile
0.7 × 10-4
210
55
0.75 × 10-4
230
75
0.7 × 10-4
240
60
0.85 × 10-4
280
90
0.1 × 10-4
0.15 × 10-4
0.15 × 10-4
0.25 × 10-4
place. In this regard, we have recently proved the
formation of bis-adducts from the corresponding monoad-
duct methanofullerenes by reductive electrolysis.9c
Related compounds 26a ,c and 27a ,c, although not
collected in Table 1, exhibited similar behavior to that
now reported for 26b and 27b. A better understanding
of the electrochemical outcome of these compounds
requires one to unravel the mechanism of the retro-
Bingel reaction, which is currently under investigation
by different research groups.27
P h ot op h ysics. To probe intramolecular electron-
transfer events in methanofullerene-based C60-exTTF
diads and triads, fluorescence and transient absorption
spectra of 12a -c and 14a -c were recorded in nonpolar
toluene and also in polar benzonitrile solutions. For the
fluorescence experiments we selected 330 nm as an
excitation wavelength, where the exTTF moieties show
a local minimum in their absorption spectra. Picosecond
transient absorption measurements, on the other hand,
were performed with 355-nm laser excitation.
In line with our previous observation, the fullerene
fluorescence, which shows in a methanofullerene refer-
ence a quantum yield of 6.0 × 10-4, is notably quenched
(Table 2). In particular, quantum yields of 0.7 × 10-4 and
0.1 × 10-4 were measured in toluene and benzonitrile,
respectively. Despite the strong fluorescence quenching,
the features of the fluorescence spectra, with a room
temperature *0-0 fluorescence maximum around 700
nm, remained unchanged relative to the methanof-
ullerene reference. Interestingly, almost no difference is
seen between the diad (12a -c) and the triad systems
(14a -c). The solvent dependence speaks for a strongly
exothermic electron transfer, evolving from the fullerene
singlet excited state (1.76 eV) to form a meta-stable
charge-separated radical pair, C60•--(exTTF)•+ (∼1.1 eV).
Complementary absorption measurements, following
a 18-ps laser pulse, revealed the instantaneous formation
of the fullerene singlet-singlet transition with a char-
acteristic maximum around 900 nm. While in the metha-
nofullerene reference a slow intersystem crossing (i.e.,
lifetime of around 1.8 ns) to the triplet manifold follows
this initial photoexcitation, in 12a -c and 14a -c the
singlet excited states decay appreciably faster. In toluene
the lifetime ranges between 210 and 280 ps, and in
benzonitrile it is as short as 50 ps. Differential absorption
changes taken at the conclusion of these rapid decays
allowed us to identify the product of these intramolecular
processes. They show the fingerprint of the one-electron-
oxidized form of exTTF, (exTTF)•+, with maxima typically
at 660 nm (i.e., 12a and 14a ) and 680 nm (i.e., 12b and
14b). The reduced electron acceptor, C60•-, shows its
strongest absorption at 1040 nm.
Su m m a r y a n d Con clu sion s
In summary, we have carried out the synthesis of the
first C60/exTTF ensembles by using the Bingel cyclopro-
panation chemical approach with different donor (exTTF)/
acceptor (C60) stoichiometries (D-A, D-A-D, A-D-A).
While substituted malonates bearing one or two exTTF
donor units react with C60 to afford the expected diads
(12a -c) and triads (14a -c) without formation of other
remarkable byproducts, the reaction of exTTF endowed
with two malonate moieties yields different products. In
particular, novel diads (26a -c) and triads (25 and 27a -
c) were obtained together with the intramolecular bis-
adducts (28b,c).
The electrochemical data reveal that both exTTF and
C60 electroactive moieties do not interact in the ground
state. The CV studies of diad 26b and triad 27b showed
the presence of bis-adducts 28b in their voltammogram.
Although formation of 28b is not clear at present,
formation under reductive electrochemical conditions is
suggested.
Theoretical calculations at the semiempirical PM3 level
predict the existence of different conformational isomers
for triads 14 depending upon the orientation, that is,
either up or down, of the 1,3-dithiole rings of the exTTF
units, as well as for diads 28, for which different
regioisomers are energetically favored.
Photophysical studies clearly show the fingerprint of
the radical cation exTTF•+, with maxima typically at
around 660-680 nm, and the radical anion C60•-, which
shows its strongest absorption at 1040 nm, thus confirm-
ing the photoinduced electron transfer and the formation
of the charge-separated state in the compounds studied.
Exp er im en ta l Section
Cyclic voltammograms were recorded on a potentiostat/
galvanostat, equipped with Model 250 software for electro-
chemical analysis by using a GCE as working electrode, SCE
as reference electrode, Bu4N+ClO4- (0.1 M), CH2Cl2 as solvent,
and scan rate of 200 mV/s.
Syn th esis of C60-exTTF Dia d s (12a -c). To a solution of
C60 (72 mg, 0.10 mmol), CBr4 (50 mg, 0.15 mmol), and the
respective ethyl malonate derivative (10a -c) (0.15 mmol) in
toluene at room temperature was added DBU (45µL, 0.30
mmol). The reaction was monitored by TLC, and after 2 h,
formation of bisadducts was observed. The solvent was re-
moved under reduced pressure. Purification of products was
achieved by column chromatography on silica gel, first with
cyclohexane to elute the unreacted C60, and then cyclohexane:
toluene (1:1) as the eluent. Further purification was ac-
complished by three centrifugations using hexane, methanol,
and ethyl ether as solvents.
(26) Moonem, N. N. P.; Thilgen, C.; Echegoyen, L.; Diederich, F.
Chem. Commun. 2000, 335.
(27) (a) Knight, B.; Mart´ın, N.; Ohno, T.; Ort´ı, E.; Rovira, C.;
Veciana, J .; Vidal-Gancedo, J .; Viruela, P.; Viruela, R.; Wudl, F. J . Am.
Chem. Soc. 1997, 109, 9871. (b) Crassous, J .; Rivera, J .; Fender, N. S.;
Shu, L.; Echegoyen, L.; Thilgen, C.; Herrmann, A.; Diederich, F. Angew.
Chem., Int. Ed. Engl. 1999, 38, 1613. (c) Burley, G. A.; Keller, P. A.;
Pyne, S. G.; Ball, G. E. Chem. Commun., 2001, 563.
61-[9,10-Bis(1,3-d it h iol-2-ylid en e)-9,10-d ih yd r o-2-a n -
th r a cen ylm eth yloxyca r bon yl]-61-(eth oxyca r bon yl)-1,2-
m eth a n o[60]fu ller en e (12a ). 32% yield (85% based on
unreacted C60). FTIR (KBr): 2922, 2853, 1743 (CdO), 1637,
1545, 1511, 1450, 1425, 1265, 1230, 1174, 1094, 1057, 1019,
J . Org. Chem, Vol. 68, No. 3, 2003 787

Gonza´lez et al.
1
800, 753, 703, 644, 580, 551, 526 (C60) cm-1. H NMR (CDCl3/
(3.18); S, 27.81 (28.80). IR (KBr): 3060, 2960, 2920, 2850, 1750
CS2 1/1, 300 MHz), δ: 7.60-7.39 (7H, m, ArH), 6.31-6.28 (4H,
m, CHd), 5.62 (1H, AB, J ) 11.0 Hz, ArCH2O), 5.54 (1H, AB,
J ) 11.0 Hz, ArCH2O), 4.51 (2H, q, J ) 7.1 Hz, OCH2), 1.41
(3H, t, J ) 7.1 Hz, CH3). 13C NMR (CDCl3, 75 MHz), δ: 163.02
(CdO), 162.92 (CdO), 144.33, 144.23, 144.02, 143.76, 143.74,
143.50, 143.00, 142.85, 142.07, 140.88, 139.96, 138.80, 137.60,
135.22, 134.89, 134.29, 131.44, 126.27, 125.44, 125.42, 125.18,
(CdO), 1735 (CdO), 1550, 1510, 1450, 1425, 1375, 1330, 1290,
1260, 1150, 1000, 900, 890, 835, 810 cm-1 1H NMR (CDCl3,
.
300 MHz), δ: 7.68-7.62 (7H, m, ArH), 7.29-7.21 (7H, m, ArH),
6.26-6.21 (8H, m, CH)), 5.23 (4H, s, CH2O), 3.54 (2H, s, CH2).
13C NMR (CDCl3, 75 MHz), δ: 166.14 (2CdO), 135.31, 135.12,
135.21, 135.10, 132.63, 132.61, 125.87, 125.85, 125.60, 125.10,
124.83, 124.77, 124.64, 124.58, 121.51, 121.50, 121.47, 117.15,
117.12, 117.10, 117.06, 117.02, 116.98, 116.96, 116.95, 67.04
3
124.50, 124.40, 124.13, 116.58, 116.41, 116.33, 77.17 (Csp C60),
74.32 (Csp C60), 68.48 (CH2O), 63.25 (CH2O), 51.86 (C), 13.93
(2CH2O), 41.64 (CH2). MS m/z (%): 888 (M+, 86), 830 (M+
-
3
(CH3). MS m/z (%): 1244 (M+, 20). UV-vis (CH2Cl2) λmax (log
ꢀ): 436 (sh, 4.37), 428 (4.37), 416 (sh, 4.34), 366 (4.37), 328
(4.63), 258 (5.12), 242 (5.10) nm.
S(CH)2, 18). UV-vis (CH2Cl2) λmax (log ꢀ): 432 (4.99), 412 (sh,
4.91), 366 (4.77), 274 (4.61), 240 (2.54) nm.
Di[9,10-bis(4,5-d im eth ylth io-1,3-d ith iol-2-ylid en e)-9,10-
d ih yd r o-2-a n th r a cen ylm eth yl] Ma lon a te (13b). 57% yield.
Mp: 183-185 °C (dec). Anal. (Calcd) for C53H44S16O4: C, 50.92
(50.64); H, 3.78 (3.53). IR (KBr): 2960, 2930, 2860, 1760 (Cd
O), 1745 (CdO), 1535, 1500, 1450, 1425, 1320, 1280, 1140, 980,
930, 755 cm-1. 1H NMR (CDCl3, 300 MHz), δ: 7.53-7.26 (14H,
m, ArH), 5.25 (4H, s, CH2O), 3.53 (2H, s, CH2), 2.40-2.37 (24H,
s, SCH3). 13C NMR (CDCl3, 75 MHz), δ: 166.09 (CdO), 135.01,
134.91, 134.66, 134.64, 134.44, 133.20, 131.69, 126.38, 126.07,
125.71, 125.63, 125.37, 125.12, 125.01, 123.10, 67.05 (2CH2O),
41.66 (CH2), 19.09 (8SCH3). MS m/z (%): 1255 (M+, 52). UV-
vis (CH2Cl2) λmax (log ꢀ): 444 (5.12), 376 (4.88), 278 (5.02), 246
(5.35) nm.
Di[9,10-b is(1,3-d it h iol-4,5-et h ylen ed it h io-2-ylid en e)-
9,10-d ih yd r o-2-a n th r a cen ylm eth yl] Ma lon a te (13c). 35%
yield. Mp: 215-218 °C (dec). FTIR (KBr): 2922, 2850, 1734
(CdO), 1560, 1541, 1508, 1458, 1412, 1294, 1144, 1009, 754
cm-1. 1H NMR (CDCl3, 200 MHz), δ: 7.49-7.44 (8H, m, ArH),
7.31-7.24 (6H, m, ArH), 5.25 (4H, s, CH2O), 3.54 (2H, s, CH2),
3.28-3.26 (16H, m, SCH2). 13C NMR (CDCl3, 50 MHz), δ:
166.0 (2CdO), 134.8, 134.4, 133.3, 130.0, 126.3, 125.6, 125.4,
125.3, 125.2, 111.0, 66.9 (2CH2O), 41.5 (CH2), 29.5 (8SCH2).
MS m/z (%): 1248 (M+, 2). UV-vis (CH2Cl2) λmax (log ꢀ): 450
(4.70), 430 (sh, 4.59), 388 (4.38), 278 (4.61), 242 (4.96) nm.
Syn th esis of (exTTF )2-C60 Tr ia d s (14a -c). To a solu-
tion of C60 (72 mg, 0.10 mmol), CBr4 (50 mg, 0.15 mmol), and
the respective malonate derivative (13a -c) (0.15 mmol) in
toluene at room temperature was added DBU (45µL, 0.30
mmol). The reaction was monitored by TLC. After 4-6 h
formation of bis-adducts was observed and the reaction was
stopped. The solvent was removed under reduced pressure.
Purification of products was achieved by column chromatog-
raphy on silica gel, first with cyclohexane to elute the unre-
acted C60 and then using cyclohexane:toluene (1:1) as the
eluent. Further purification was accomplished by three cen-
trifugations using hexane, methanol, and ethyl ether as
solvents, respectively.
61-[9,10-Bis(4,5-d im eth ylth io-1,3-d ith iol-2-ylid en e)-9,-
10-d ih yd r o-2-a n th r a cen ylm eth yloxyca r bon yl]-61-(eth ox-
ycar bon yl)-1,2-m eth an o[60]fu ller en e (12b). 27% yield (73%
based on unreacted C60). FTIR (KBr): 2968, 2925, 2919, 2916,
1745 (CdO), 1637, 1541, 1534, 1507, 1494, 1451, 1425, 1266,
1231, 1203, 1186, 1095, 1057, 1018, 753, 703, 669, 581, 552,
526 cm-1 1H NMR (CDCl3/CS2 1/1, 300 MHz), δ: 7.48-7.20
.
(7H, m, ArH), 5.66 (1H, AB, J ) 11.5 Hz, ArCH2O), 5.55 (1H,
AB, J ) 11.5 Hz, ArCH2O), 4.53 (2H, q, J ) 7.1 Hz, OCH2),
2.40 (12H, s, SCH3), 1.42 (3H, t, J ) 7.1 Hz, CH3). 13C NMR
(CDCl3/CS2 1/1, 75 MHz), δ: 163.10 (CdO), 163.06 (CdO),
145.04, 144.94, 144.90, 144.85, 144.67, 144.60, 144.44, 144.13,
144.03, 143.68, 143.58, 142.84, 142.77, 142.60, 142.01, 141.59,
141.46, 140.70, 140.66, 139.51, 138.05, 138.00, 135,10, 134,-
82, 134,26, 134,23, 132,65, 132,37, 132,31, 130,64, 127,24, 126,-
52, 126,44, 126,24, 126,18, 125,59, 125,55, 125,29, 123,04,
3
3
122,78, 77,21 (Csp C60), 71,24 (Csp C60), 68,35 (CH2O), 63,34
(CH2O), 51,70 (C), 19,16 (SCH3), 19,12 (SCH3), 19,07 (2SCH3),
14,17 (CH3). MS m/z (%): 1427 (M+, 31), 720 (C60, 10). UV-
vis (CH2Cl2) λmax (log ꢀ): 442 (4.42), 428 (sh, 4.38), 362 (4.45),
328 (4.63), 258 (5.14), 246 (5.12) nm.
61-[9,10-Bis(1,3-d it h iol-4,5-et h ylen ed it h io-2-ylid en e)-
9,10-d ih yd r o-2-a n th r a cen ylm eth yloxyca r bon yl]-61-(eth -
oxyca r bon yl)-1,2-m eth a n o[60]fu ller en e (12c). 18% yield
(63% based on unreacted C60). FTIR (KBr): 2970, 1919, 1745
(CdO), 1639, 1541, 1507, 1451, 1424, 1384, 1365, 1284, 1266,
1252, 1231, 1203, 1186, 1175, 1110, 1095, 1058, 1017, 754, 704,
641, 581, 563, 552, 526 (C60) cm-1 1H NMR (CDCl3/CS2 1/1,
.
300 MHz), δ: 7.51-7.27 (7H, m, ArH), 5.60 (1H, AB, J ) 11.7
Hz, ArCH2O), 5.53 (1H, AB, J ) 11.7 Hz, ArCH2O), 4.51 (2H,
q, J ) 7.1 Hz, OCH2), 3.32-3.29 (8H, m, SCH2), 1.43 (3H, t, J
) 7.1 Hz, CH3). 13C NMR (CDCl3/CS2 1/1, 75 MHz), δ: 162.89
(CdO), 162.77 (CdO), 145.04, 145.02, 144.94, 144.85, 144.81,
144.67, 144.64, 144.55, 144.44, 144.41, 144.35, 144.20, 144.15,
143.61, 143.52, 142.88, 142.74, 142.68, 142.64, 142.52, 141.93,
141.50, 140.60, 139.42, 138.31, 138.05, 135.13, 134.90, 134.29,
132.51, 130.98, 128.75, 127.22, 126.40, 126.15, 125.57, 125.29,
61-Bis[9,10-b is(1,3-d it h iol-2-ylid en e)-9,10-d ih yd r o-2-
a n t h r a c e n y lm e t h y lo x y c a r b o n y l]-1,2-m e t h a n o [60]-
fu ller en e (14a ). 25% yield (60% based on unreacted C60).
FTIR (KBr): 2918, 2848, 1745 (CdO), 1541, 1507, 1457, 1428,
3
125.23, 122.75, 122.45, 111.14, 110.90, 110.83, 77.21 (Csp C60),
3
71.25 (Csp C60), 68.27 (CH2O), 63.22 (CH2O), 46.85 (C), 29.73
(SCH2), 14.19 (CH3). MS m/z (%): 1424 (M+, 11). UV-vis (CH2-
Cl2) λmax (log ꢀ): 454 (4.27), 428 (4.17), 328 (4.55), 258 (5.06),
242 (sh, 5.01) nm.
1229, 1182, 800, 756, 701, 669, 645, 577, 527 (C60) cm-1 1H
.
NMR (CDCl3, 300 MHz), δ: 7.87-7.27 (14H, m, ArH), 6.31-
6.19 (8H, m, CHd), 5.53 (4H, s br, CH2O). 13C NMR (CDCl3,
75 MHz), δ: 163.30 (CdO), 144.95, 144.94, 144.75, 144.70,
144.49, 144.31, 144.25, 143.65, 143.03, 142.78, 142.65, 142.06,
141.70, 141.69, 140.64, 138.84, 136.70, 136.69, 136.56, 136.55,
135.81, 135.63, 135.11, 135.00, 132.13, 126.68, 126.10, 126.01,
125.57, 125.02, 125.23, 124.89, 121.61, 121.37, 117.18, 77.20
Syn th esis of Di[9,10-bis(1,3-d ith iol-2-ylid en e)-9,10-d i-
h yd r o-2-a n th r a cen ylm eth yl] Ma lon a tes (13a -c). To a
solution of compound 9a -c (0.5 mmol) in dry CH2Cl2 (30 mL)
at room temperature and under argon atmosphere was added
dry pyridine (35 µL, 0.495 mmol) was added. The mixture was
cooled in an ice bath. Malonic acid dichloride (24.5 mg, 0.245
mmol) in dry CH2Cl2 (1 mL) was added dropwise during 10
min. The mixture was stirred at 0 °C for 2 h, allowed to warm
to 20 °C, and then let stand overnight. Water (75 mL) was
added and the residue extracted with CH2Cl2 (3 × 100 mL).
The combined extracts were dried (Na2SO4) and filtered out,
and the solvent was removed under reduced pressure. Puri-
fication of products was achieved by column chromatography
on silica gel using hexane:dichloromethane mixtures as eluent.
3
3
(Csp C60), 71.32 (Csp C60), 68.79 (CH2O), 68.75 (CH2O), 47.21
(C). MS m/z (%): 1607 (M+, 5), 720 (C60, 24). UV-vis (CH2Cl2)
λmax (log ꢀ): 436 (4.37), 418 (sh, 4.35), 368 (4.39), 328 (4.46),
256 (4.94), 234 (5.10) nm.
61-Bis[9,10-bis(4,5-d im eth ylth io-1,3-d ith iol-2-ylid en e)-
9,10-d ih yd r o-2-a n t h r a ce n ylm e t h yloxyca r b on yl]-1,2-
m eth a n o[60]fu ller en e (14b). 30% yield (70% based on
unreacted C60). FTIR (KBr): 2918, 2850, 1748 (CdO), 1705
(CdO), 1576, 1540, 1496, 1452, 1424, 1265, 1226, 1200, 1184,
Di[9,10-bis(1,3-dith iol-2-yliden e)-9,10-dih ydr o-2-an th r a-
cen ylm eth yl] Ma lon a te (13a ). 58% yield. Mp: 183-185 °C
(dec). Anal. (Calcd) for C45H28S8O4: C, 61.43 (60.81); H, 3.86
1094, 1057, 966, 890, 824, 753, 669, 642, 578, 558, 526 (C60
)
cm-1. 1H NMR (CDCl3, 300 MHz), δ: 7.52-7.25 (14H, m, ArH),
788 J . Org. Chem., Vol. 68, No. 3, 2003

Bingel-type C60/ exTTF Diads and Triads
5.65 (1H, AB, J ) 12.2 Hz, CH2O), 5.64 (1H, AB, J ) 11.6 Hz,
CH2O), 5.54 (1H, AB, J ) 11.6 Hz, CH2O), 5.52 (1H, AB, J )
12.2 Hz, CH2O), 2.40-2.39 (24H, m, SCH3). 13C NMR (CDCl3,
75 MHz), δ: 167.75 (CdO), 163.34 (CdO), 145.02, 144.96,
144.89, 144.73, 144.61, 144.52, 144.25, 143.66, 143.05, 142.65,
142.06, 142.03, 141.65, 141.51, 140.66, 138.78, 138.71, 135.15,
135.00, 134.91, 134.36, 134.34, 132.69, 132.41, 131.99, 131.91,
130.89, 130.87, 128.82, 128.77, 127.03, 126.55, 126.40, 125.70,
(CdO), 1603, 1560, 1541, 1498, 1458, 1412, 1369, 1147, 1097,
1032, 964, 810, 771 cm-1. 1H NMR (CDCl3, 200 MHz), δ: 7.44
(2H, d, J 3,4 ) 8.5 Hz, ArH4), 7.05 (2H, d, J 1,3 ) 2.5 Hz, ArH1),
6.82 (2H, dd, J 3,4 ) 8.5 Hz, J 1,3 ) 2.5 Hz, ArH3), 4.5 (4H, t, J
) 4.6 Hz, ArOCH2), 4.24 (4H. t, J ) 4.6 Hz, CH2OCO), 4.20
(4H, q, J ) 7.1 Hz, OCH2CH3), 3.44 (4H, s, CH2), 2.38 (12H, s,
SCH3), 1.25 (6H, t, J ) 7.1 Hz, CH3). 13C NMR (CDCl3, 50
MHz), δ: 166.49 (2CdO), 166.23 (2CdO), 156.54 (2C2), 136.27,
129.73, 128.08, 126.59, 126.19, 125.31, 123.06, 111.98, 111.66,
65.83 (2ArOCH2), 63.54 (2CH2CO), 61.55 (2OCH2CH3), 41.39
(CH2), 19.09 (2SCH3), 18.96 (2SCH3), 14.00 (2CH3). MS m/z
(%): 912 (M+, 100). UV-vis (CH2Cl2) λmax (log ꢀ): 432 (4.38),
416 (sh, 4.32), 366 (4.17), 248 (4.66), 236 (sh, 4.58) nm.
3
125.66, 125.58, 125.36, 122.97, 122.71, 77.20 (Csp C60), 71.21
3
(Csp C60), 68.63 (CH2O), 68.12 (CH2O), 51.70 (C), 19.22 (SCH3),
19.20 (SCH3). MS m/z (%): 1976 (M+, 31), 720 (C60, 100). UV-
vis (CH2Cl2) λmax (log ꢀ): 442 (4.56), 420 (sh, 4.48), 370 (4.50),
328 (4.57), 258 (5.09), 242 (5.13), 234 (5.15) nm.
61-Bis[9,10-bis(1,3-dith iol-4,5-eth ylen edith io-2-yliden e)-
9,10-d ih yd r o-2-a n t h r a ce n ylm e t h yloxyca r b on yl]-1,2-
m eth a n o[60]fu ller en e (14c). 16% yield (65% based on
unreacted C60). FTIR (KBr): 2920, 1747 (CdO), 1635, 1540,
1506, 1455, 1423, 1284, 1226, 1201, 1058, 754, 668, 642, 526
9,10-Bis(1,3-d it h iol-4,5-et h ylen ed it h io-2-ylid en e)-2,6-
b is(1,4,8-t r ioxa -5,7-d ioxod e cyl)-9,10-d ih yd r oa n t h r a -
cen e (24c). 58% yield. Mp: 67-71 °C. Anal. (Calcd) for
C
38H36S8O10
2924, 2852, 1730 (CdO), 1686, 1603, 1560, 1508, 1452, 1406,
1369, 1273, 1217, 1147, 1097, 1026, 921, 791, 762, 748 cm-1
1H NMR (CDCl3, 300 MHz), δ: 7.41 (2H, d, J 3,4 ) 8.6 Hz,
ArH4), 7.02 (2H, d, J 1,3 ) 2.4 Hz, ArH1), 6.84 (2H, dd, J 3,4
: C, 49.87 (50.22); H, 4.16 (3.96). FTIR (KBr):
1
(C60) cm-1. H NMR (CDCl3/CS2 1/1, 300 MHz), δ: 7.44-7.27
.
(14H, m, ArH), 5.63 (2H, AB, J ) 11.0 Hz, CH2O), 5.52-5.45
(2H, AB, J ) 11.0 Hz, CH2O), 3.31-3.28 (16H, m, SCH2). MS
m/z (%): 1967 (M+, 59). UV-vis (CH2Cl2) λmax (log ꢀ): 452
(4.39), 428 (sh, 4.29), 326 (4.47), 256 (sh, 5.01), 234 (5.13) nm.
)
8.6 Hz, J 1,3 ) 2.4 Hz, ArH3), 4.55 (4H, t, J ) 4.4 Hz, ArOCH2),
4.26 (4H, t, J ) 4.4 Hz, CH2OCO), 4.20 (4H, q, J ) 7.1 Hz,
OCH2CH3), 3.45 (4H, s, CH2), 3.30 (4H, s, SCH2), 3.29 (4H, s,
SCH2), 1.27 (6H, t, J ) 7.1 Hz, CH3). 13C NMR (CDCl3, 50
MHz), δ: 166.56 (2CdO), 166.28 (2CdO), 156.54 (2C2), 136.30,
128.52, 128.11, 126.77, 123.56, 111.98, 111.94, 110.90, 110.74,
65.92 (2ArOCH2), 63.63 (2CH2CO), 61.59 (2OCH2CH3), 41.43
(CH2), 29.56 (2SCH2), 29.54 (2SCH2), 14.05 (2CH3). MS m/z
(%): 908 (M+, 100). UV-vis (CH2Cl2) λmax (log ꢀ): 442 (4.05),
424 (sh, 3.96), 384 (3.76), 250 (4.32), 234 (4.31) nm.
Syn th esis of Bism a lon a tes (23 a n d 24a-c). To a solution
of the respective alcohol derivative (21 or 22a -c) (0.25 mmol)
in dry CH2Cl2 (30 mL) at room temperature and under argon
atmosphere was added dry pyridine (68 µL, 0.85 mmol). The
mixture was cooled in an ice bath. Ethoxycarbonylacetic acid
chloride (93 µL, 0.75 mmol) in dry CH2Cl2 (1 mL) was added
dropwise during 10 min. The mixture was stirred at 0 °C for
2 h and then allowed to warm to 20 °C to stand overnight.
Water (75 mL) was added and the residue extracted with CH2-
Cl2 (3 × 100 mL). The combined extracts were dried (Na2SO4)
and filtered out, and the solvent was removed under reduced
pressure. Purification of products was achieved by column
chromatography on silica gel using hexane:dichloromethane
mixtures as eluent.
Syn th esis of Dia d s 26b,c a n d 28b,c. To a solution of C60
(72 mg, 0.10 mmol), CBr4 (33.2 mg, 0.10 mmol), and the
malonate derivative (23 or 24a -c) (0.10 mmol) in toluene at
0 °C was added DBU (30µL, 0.20 mmol) in o-DCB (1 mL). The
reaction was monitored by TLC, and after 10-20 min, the
reaction was stopped, since formation of products resulting
from multiple addition was observed. Isolation and purification
of products were achieved by column chromatography on silica
gel first with toluene to elute the unreacted C60 and then using
toluene:ethyl acetate (50:1) as the eluent to separate the
reaction products, which eluted in the order 25 or 27a -c then
26a -c and finally 28a -c. Further purification was accom-
plished by three centrifugations using hexane, methanol, and
ether as solvents.
9,10-Bis(4,5-d im eth ylth io-1,3-d ith iol-2-ylid en e)-2,6-bis-
(1,5-d ioxa -2,4-d ioxoh ep tyl)-9,10-d ih yd r oa n th r a cen e (23).
64% yield. Mp: 129-131 °C. FTIR (KBr): 2924, 2852, 2740,
1763 (CdO), 1738 (CdO), 1602, 1560, 1533, 1469, 1410, 1367,
1
1329, 1261, 1238, 1188, 1134, 1094, 1026, 966, 891 cm-1. H
NMR (CDCl3, 300 MHz), δ: 7.54 (2H, d, J 3,4 ) 8.4 Hz, ArH4),
7.31 (2H, d, J 1,3 ) 2.2 Hz, ArH1), 7.07 (2H, dd, J 3,4 ) 8.4 Hz,
J 1,3 ) 2.2 Hz, ArH3), 4.29 (4H, q, J ) 7.3 Hz, OCH2), 3.65 (4H,
s, CH2), 2.40 (12H, s, SCH3), 1.35 (6H, t, J ) 7.3 Hz, CH3). 13
C
Dia d 26a . 22% yield. FTIR (KBr): 2963, 1747 (CdO), 1603,
NMR (CDCl3, 50 MHz) δ: 166.03 (2CdO), 164.91 (2CdO),
148.36 (2C2), 136.01, 132.82, 132.45, 126.28, 125.90, 121.75,
118.97, 118.29, 61.85 (2OCH2), 41.72 (CH2), 19.10 (2SCH3),
19.06 (2SCH3), 14.14 (2CH3). MS m/z (%): 847 (M+ + Na, 100).
UV-vis (CH2Cl2) λmax (log ꢀ): 242 (4.23), 268 (sh, 3.88), 373
(3.74), 440 (3.98) nm.
1560, 1546, 1508, 1464, 1367, 1263, 1231, 1187, 1155, 1097,
1
1056, 862, 801, 657, 581, 526 cm-1. H NMR (CDCl3/CS2 1:1,
300 MHz), δ: 7.52 (1H, d, J 3,4 ) J 7,8 ) 8.5 Hz, ArH4 or ArH8),
7.51 (1H, d, J 3,4 ) J 7,8 ) 8.5 Hz, ArH4 or ArH8), 7.15 (2H, d,
J 1,3 ) J 5,7 ) 2.3 Hz, ArH1, ArH5), 6.76 (2H, dd, J 3,4 ) J 7,8
)
8.5 Hz, J 1,3 ) J 5,7 ) 2.3 Hz, ArH3, ArH7), 6.28-6.26 (4H, m,
CHd), 4.56-4.49 (4H, m, CH2O), 4.40-4.38 (4H, m, OCH2-
CH3), 4.24-4.17 (4H, m, CH2O), 3.40 (2H, s, CH2), 1.47 (6H, t,
J ) 7.1 Hz, CH3). 13C NMR (CDCl3/CS2 1/1, 75 MHz), δ: 166.10
(CdO), 165.83 (CdO), 163.18 (CdO), 162.86 (CdO), 156.21 (C2
or C6), 156.04 (C2 or C6), 145.17, 145,12, 145.00, 144.98, 144.89,
144.69, 144.62, 144.45, 144.40, 144.20, 144.16, 143.66, 143.51,
142.81, 142.72, 142.67, 142.59, 142.02, 141.95, 141.55, 140.73,
140.71, 140.65, 139.33, 138.17, 138.12, 137.02, 136.85, 134.70,
134.60, 128.85, 128.76, 126.06, 121.39, 117.09, 111.88, 111.34,
9,10-Bis(1,3-d it h iol-2-ylid en e)-2,6-b is(1,4,8-t r ioxa -5,7-
d ioxod ecyl)-9,10-d ih yd r oa n t h r a cen e (24a ). 62% yield.
Mp: 62-65 °C. FTIR (KBr): 2767, 1734 (CdO), 1603, 1545,
1508, 1458, 1412, 1369, 1026, 966, 798, 756 cm-1 1H NMR
.
(CDCl3, 200 MHz), δ: 7.59 (2H, d, J 3,4 ) 8.5 Hz, ArH4), 7.22
(2H, d, J 1,3 ) 2.4 Hz, ArH1), 6.82 (2H, dd, J 3,4 ) 8.5 Hz, J 1,3
)
2.4 Hz, ArH3), 6.29 (4H, s, CH)), 4.54 (4H, t, J ) 4.2 Hz,
ArOCH2), 4.25 (4H, t, J ) 4.2 Hz, CH2OCO), 4.20 (4H, q, J )
7.1 Hz, OCH2CH3), 3.44 (4H, s, CH2), 1.26 (6H, t, J ) 7.1 Hz,
CH3). 13C NMR (CDCl3, 50 MHz), δ: 166.58 (2CdO), 166.31
(2CdO), 156.36 (2C2), 137.052, 134.40, 128.96, 126.12, 120.00,
117.10, 112.06, 111.07, 65.93 (2ArOCH2), 63.70 (2CH2O), 61.61
(2OCH2CH3), 41.45 (CH2), 14.13 (2CH3). MS m/z (%): 728 (M+,
22), 614 (M+ - COCH2CO2Et, 32), 500 (100). UV-vis (CH2-
Cl2) λmax (log ꢀ): 424 (4.53), 412 (sh, 4.10), 362 (4,31), 242 (4.73)
nm.
3
3
111.19, 111.04, 77.21 (Csp C60), 71.22 (Csp C60), 65.72 (CH2O),
65.07 (CH2O), 63.52 (2CH2O), 63.34 (CH2O), 61.43 (CH2O),
51.82 (C), 41.19 (CH2), 14.20 (CH3), 14.08 (CH3). MS m/z (%):
1470 (M+ + Na, 60). UV-vis (CH2Cl2) λmax (log ꢀ): 426 (4.38),
410 (sh, 4.37), 362 (4.47), 324 (4.63), 254 (5.11) nm.
Dia d 26b. 13% yield. FTIR (KBr): 2918, 1745 (CdO), 1601,
1536, 1496, 1461, 1425, 1367, 1226, 1098, 1058, 1024, 953, 752,
1
9,10-Bis(4,5-d im eth ylth io-1,3-d ith iol-2-ylid en e)-2,6-bis-
(1,4,8-tr ioxa-5,7-dioxodecyl)-9,10-dih ydr oan th r acen e (24b).
70% yield. Mp: 57-60 °C. Anal. (Calcd) for C38H40S8O10: C,
49.24 (50.00); H, 4.51 (4.62). FTIR (KBr): 2922, 2852, 1734
525 cm-1. H NMR (CDCl3, 300 MHz), δ: 7.38 (1H, d, J 3,4
)
J 7,8 ) 8.5 Hz, ArH4 or ArH8), 7.37 (1H, d, J 3,4 ) J 7,8) 8.5 Hz,
ArH4 or ArH8), 6.99 (1H, d, J 1,3 ) J 5,7 ) 2.3 Hz, ArH1 or ArH5),
6.98 (1H, d, J 1,3 ) J 5,7 ) 2.3 Hz, ArH1 or ArH5), 6.78 (2H, dd,
J . Org. Chem, Vol. 68, No. 3, 2003 789

Gonza´lez et al.
(2H, d, J 1,3 ) 2.2 Hz, ArH1), 6.78 (2H, dd, J 3,4 ) 8.4 Hz, J 1,3
2.2 Hz, ArH3), 4.69 (4H, q, J ) 7.1 Hz, OCH2), 2.43-2.37 (12H,
m, SCH3), 1.63 (6H, t, J ) 7.1 Hz, CH3). 13C NMR (CDCl3/CS2
1/1, 75 MHz), δ: 162.90 (4CdO), 154.12 (2C2), 148.03, 145.40,
145.31, 145.19, 145.15, 145.08, 145.05, 145.02, 144.86, 144.77,
144.64, 144.57, 144.53, 144.27, 143.80, 143.74, 143.70, 142.98,
142.95, 142.90, 142.78, 142.76, 142.09, 141.93, 141.64, 140.97,
140.87, 139.98, 138.10, 136.29, 136.05, 127.29, 127.23, 126.82,
126.34, 126.25, 125.90, 122.48, 118.35, 118.17, 113.18, 113.09,
J 3,4 ) J 7,8 ) 8.5 Hz, J 1,3 ) J 5,7 ) 2.3 Hz, ArH3, ArH7), 4.54-
4.52 (4H, m, OCH2), 4.42-4.38 (4H, m, OCH2CH3), 4.23-4.18
(4H, m, CH2O), 3.47-3.44 (2H, m, CH2), 2.39 (12H, s, SCH3),
1.47 (3H, t, J ) 7.1 Hz, CH3), 1.28 (3H, t, J ) 7.1 Hz, CH3).
13C NMR (CDCl3, 75 MHz), δ: 166.31 (CdO), 166.03 (CdO),
163.41 (CdO), 163.07 (CdO), 156.53 (C2 or C6), 156.39 (C2 or
C6), 145.21, 145.18, 145.07, 145.00, 144.96, 144.99, 144.80,
144.69, 144.66, 144.51, 144.46, 144.41, 144.25, 144.16, 144.13,
143.72, 143.52, 143.50, 142.76, 142.72, 142.69, 142.67, 142.62,
142.56, 142.11, 142.05, 141.99, 141.61, 141.57, 141.51, 140.75,
140.71, 139.42, 138.11, 138.05, 136.43, 136.21, 130.41, 130.13,
130.11, 130.00, 129.98, 128.06, 128.00, 127.97, 127.56, 126.63,
126.37, 126.11, 126.00, 125.82, 125.38, 123.16, 123.14, 122.98,
)
3
3
112.38, 77.21 (Csp C60), 71.26 (Csp C60), 63.58 (CH2O), 65.06
(CH2O), 51.00 (2C), 19.35 (2SCH3), 19.13 (2SCH3), 14.40 (CH3),
14.20 (CH3). MS m/z (%): 1542 (M+ - C60, 30), 822 (M+ - 2C60
,
4). UV-vis (CH2Cl2) λmax (log ꢀ): 439 (4.13), 362 (sh, 4.19), 324
3
122.88, 122.86, 111.93, 111.78, 111.47, 77.20 (Csp C60), 71.25
(4.42), 255 (4.92), 236 (sh, 4.87) nm.
3
(Csp C60), 65.78 (CH2O), 65.11 (CH2O), 63.52 (CH2O), 63.43
Tr ia d 27a . 13% yield. FTIR (KBr): 2953, 2923, 2853, 1746
(CdO), 1650, 1601, 1546, 1514, 1458, 1431, 1370, 1232, 1209,
(CH2O), 61.54 (2CH2O), 51.86 (C), 41.29 (CH2), 19.20 (CH3S),
19.16 (SCH3), 19.13 (SCH3), 19.03 (SCH3),14.21 (CH3), 14.08
(CH3). MS m/z (%): 1632 (M+, 100). UV-vis (CH2Cl2) λmax (log
ꢀ): 430 (4.35), 414 (sh, 4.31), 362 (4.44), 321 (4.60), 254 (5.08)
nm.
1182, 1098, 1058, 1019, 639, 526 cm-1 1H NMR (CDCl3/CS2
.
1/1, 300 MHz), δ: 7.48 (2H, d, J 3,4 ) 8.6 Hz, ArH4), 7.10 (2H,
d, J 1,3 ) 2.5 Hz, ArH1), 6.73 (2H, dd, J 3,4 ) 8.6 Hz, J 1,3 ) 2.5
Hz, ArH3), 6.26 (4H, s, CH)), 4.89-4.88 (4H, m, CH2O), 4.48
(4H, q, J ) 7.1 Hz, OCH2CH3), 4.39-4.38 (4H, m, CH2O), 1.49
(6H, t, J ) 7.1 Hz, CH3). 13C NMR (CDCl3/CS2 1/ 1, 75 MHz,),
δ: 163.22 (2CdO), 162.90 (2CdO), 156.07 (2C2), 145.23,
145.19, 145.04, 144.94, 144.85, 144.73, 144.66, 144.50, 144.45,
144.29, 144.22, 143.70, 143.56, 142.85, 142.76, 142.71, 142.65,
142.61, 142.05, 141.99, 141.59, 140.78, 140.68, 139.38, 138.23,
138.16, 137.00, 134.72, 128.87, 126.13, 125.18, 121.31, 117.16,
Dia d 26c. 12% yield. FTIR (KBr): 2957, 2924, 1747 (Cd
O), 1601, 1558, 1511, 1457, 1414, 1370, 1287, 1229, 1100, 1057,
1
1023, 812, 527 cm-1. H NMR (CDCl3/CS2, 2/1, 300 MHz), δ:
7.33 (1H, d, J 3,4 ) J 7,8 ) 8.3 Hz, ArH4 or ArH8), 7.32 (1H, d,
J 3,4 ) J 7,8 ) 8.3 Hz, ArH4 or ArH8), 6.94 (2H, d, J 1,3 ) J 5,7
2.5 Hz, ArH1, ArH5), 6.77 (1H, dd, J 3,4 ) J 7,8 ) 8.3 Hz, J 1,3
J 5,7) 2.5 Hz, ArH3 or ArH7), 6.74 (1H, dd, J 1 ) 8.3 Hz, J 2
)
)
)
2.5 Hz, ArH3 or ArH7), 4.56-4.17 (12H, m, OCH2), 3.44 (2H,
s, CH2), 3.33-3.27 (8H, m, SCH2), 1.49 (3H, t, J ) 7.1 Hz,
CH3), 1.28 (3H, t, J ) 7.1 Hz, CH3). 13C NMR (CDCl3/CS2, 2/1,
75 MHz), δ: 166.18 (CdO), 166.89 (CdO), 163.37 (CdO),
163.07 (CdO), 156.52 (C2 or C6), 156.28 (C2 or C6), 147.70,
145.72, 145.18, 145.00, 144.94, 144.83, 144.70, 144.64, 144.50,
144.39, 144.28, 144.15, 144.03, 144.93, 143.69, 143.61, 143.60,
143.59, 143.31, 142.73, 142.63, 142.25, 142.10, 141.96, 141.63,
141.55, 141.17, 140.84, 140.68, 139.60, 139.40, 138.05, 136.41,
136.28, 136.22, 128.78, 128.13, 128.07, 128.01, 126.72, 126.63,
122.99, 111.90, 111.84, 111.80, 111.76, 111.08, 111.01, 110.92,
3
3
111.46, 111.34, 77.20 (Csp C60), 71.26 (Csp C60), 65.68 (2CH2O),
65.06 (2CH2O), 63.36 (2CH2O), 51.36 (2C), 14.25 (2CH3). MS
m/z (%): 2166 (M+, 5), 1446 (M+ - C60, 100), 721 (C60 + H,
10). UV-vis (CH2Cl2) λmax (log ꢀ): 426 (3.96), 406 (sh, 3.96),
364 (sh, 4.16), 326 (4.42), 258 (5.05) nm.
Tr ia d 27b. 15% yield. FTIR (KBr): 2922, 2856, 1741 (Cd
O), 1599, 1556, 1493, 1461, 1420, 1265, 1228, 1204, 1054, 951,
1
525 cm-1. H NMR (CDCl3, 300 MHz), δ: 7.35 (2H, d, J 3,4
)
8.6 Hz, ArH4), 6.96 (2H, d, J 1,3 ) 2.3 Hz, ArH1), 6.75 (2H, dd,
J 3,4 ) 8.6 Hz, J 1,3 ) 2.3 Hz, ArH3), 4.95-4.87 (4H, m, OCH2),
4.57 (4H, q, J ) 7.1 Hz, OCH2CH3), 4.39-4.37 (4H, m, CH2O),
2.37 (12H, s, SCH3), 1.50 (6H, t, J ) 7.1 Hz, CH3). 13C NMR
(CDCl3, 50 MHz), δ: 163.71 (2CdO), 163.38 (2CdO), 156.46
(2C2), 145.41, 145.17, 145.08, 145.06, 145.03, 144.91, 144.81,
144.79, 144.77, 144.74, 144.72, 144.63, 144.57, 144.55, 144.40,
144.26, 143.83, 143.61, 142.98, 142.89, 142.87, 142.82, 142.77,
142.72, 142.66, 142.23, 142.18, 142.09, 141.75, 141.72, 141.70,
141.65, 140.88, 140.80, 140.79, 140.77, 139.65, 138.11, 138.06,
136.52, 129.85, 129.01, 128.22, 128.10, 127.78, 127.45, 126.66,
3
3
77.20 (Csp C60), 71.23 (Csp C60), 65.78 (2CH2O), 63.52 (2CH2O),
63.36 (CH2O), 61.47 (CH2O), 51.82 (C), 41.23 (CH2), 29.72
(SCH2), 14.09 (CH3). MS m/z (%): 1651 (M+ + Na, 100), 1628
(M+). UV-vis (CH2Cl2) λmax (log ꢀ): 444 (5.51), 426 (sh, 4.30),
376 (4.31), 316 (sh, 4.62), 252 (5.05) nm.
Dia d 28b (Regioisom er ic Mixtu r e). 8% yield. FTIR
(KBr): 2923, 2853, 1745 (CdO), 1668, 1591, 1557, 1495, 1460,
1426, 1367, 1287, 1226, 1172, 1101, 1057, 962, 860, 808, 750,
1
525 (C60) cm-1. H NMR (CDCl3/CS2, 2/1, 300 MHz), δ: 6.96-
3
126.11, 125.93, 122.48, 112.62, 112.13, 77.19 (Csp C60), 71.39
6.57 (6H, m, ArH), 5.0-4.2 (12H, m, CH2), 1.64-1.55 (6H, m,
CH3). MS m/z (%): 1644 (M+ + O, 25). UV-vis (CH2Cl2) λmax
(log ꢀ): 430 (4.33), 414 (sh, 4.30), 366 (4.46), 318 (sh, 4.62),
250 (4.64) nm.
3
(Csp C60), 65.89 (2CH2O), 65.18 (2CH2O), 63.61 (2CH2O), 52.00
(2C), 19.16 (2SCH3), 19.06 (2SCH3), 14.30 (CH3), 14.11 (CH3).
MS m/z (%): 2350 (M+, 90), 1629 (M+ - C60, 10). UV-vis (CH2-
Cl2) λmax (log ꢀ): 428 (3.97), 414 (sh, 3.95), 366 (sh, 4.18), 326
(4.46), 256 (4.94) nm.
Dia d 28c (Regioisom er ic Mixtu r e). 6% yield. FTIR
(KBr): 2955, 2923, 2851, 1747 (CdO), 1603, 1559, 1508, 1456,
1378, 1286, 1230, 1172, 1098, 1062, 1028, 862, 764, 706, 547,
526 cm-1. MS m/z (%): 1649 (M+ + Na, 100). UV-vis (CH2-
Cl2) λmax (log ꢀ): 442 (4.99), 376 (4.23), 248 (4.18) nm.
Syn th esis of Tr ia d s 25 a n d 27a -c. To a solution of C60
(432 mg, 0.60 mmol), CBr4 (99.6 mg, 0.30 mmol), and the
dimalonate derivative (23 or 24a -c) (0.10 mmol) in toluene
at 0 °C was added DBU (60µL, 0.40 mmol) in o-DCB (1 mL)
was added. The reaction was monitored by TLC, and after 10-
30 min, the reaction was stopped, since formation of many
addition products to C60 was observed. Purification of products
was achieved by column chromatography on silica gel, first
with toluene to elute the unreacted C60 and then using toluene:
ethyl acetate (50:1) as the eluent. Further purification was
accomplished by three centrifugations using hexane, methanol,
and ethyl ether as solvents, respectively.
Tr ia d 27c. 12% yield. FTIR (KBr): 2955, 2921, 2850, 1744
(CdO), 1672, 1592, 1559, 1456, 1436, 1323, 1291, 1230, 1204,
1156, 1139, 1119, 1097, 1061, 721, 694, 526 cm-1 1H NMR
.
(CDCl3/CS2, 1/1, 300 MHz), δ: 7.68 (2H, d, J 3,4 ) 8.2 Hz, ArH4),
6.88 (2H, d, J 1,3 ) 2.5 Hz, ArH1), 6.71 (2H, dd, J 3,4 ) 8.2 Hz,
J 1,3 ) 2.5 Hz, ArH3), 4.93-4.83 (4H, m, OCH2), 4.55 (4H, q, J
) 7.1 Hz, OCH2CH3), 4.37-4.29 (4H, m, CH2O), 3.30-3.26 (8H,
m, SCH2), 1.50 (6H, t, J ) 7.1 Hz, CH3). 13C NMR (CDCl3/
CS2, 1/1, 75 MHz), δ: 163.07 (CdO), 163.05 (CdO), 162.68 (Cd
O), 156.13 (2C2), 136.30, 145.12, 145.10, 144.92, 144.85, 144.76,
144.64, 144.56, 144.44, 144.40, 144.36, 144.31, 144.19, 144.08,
143.62, 143.61, 143.58, 143.55, 143.53, 142.86, 142.74, 142.67,
142.56, 142.55, 142.04, 141.89, 141.56, 141.54, 141.47, 140.78,
140.74, 140.60, 139.30, 138.04, 136.25, 133.39, 128.88, 128.82,
128.54, 128.16, 128.12, 128.05, 128.03, 128.01, 126.64, 126.61,
126.56, 126.53, 126.51, 122.64, 111.90, 111.35, 111.33, 110.98,
3
3
Tr ia d 25. 8% yield. FTIR (KBr): 2961, 2920, 2852, 1741
(CdO), 1600, 1531, 1491, 1462, 1416, 1371, 1261, 1229, 1198,
77.21 (Csp C60), 71.15 (Csp C60), 65.64 (2CH2O), 64.84 (2CH2O),
63.22 (2CH2O), 51.73 (2C), 30.40 (SCH2), 29.81 (2SCH2), 29.78
(SCH2), 14.24 (2CH3). UV-vis (CH2Cl2) λmax (log ꢀ): 446 (4.07),
428 (sh, 4.06), 322 (4.59), 254 (5.05) nm.
1095, 1020, 960, 801, 702, 877, 526 cm-1 1H NMR (CDCl3/
.
CS2 1:1, 300 MHz), δ: 7.60 (2H, d, J 3,4 ) 8.4 Hz, ArH4), 7.00
790 J . Org. Chem., Vol. 68, No. 3, 2003

Bingel-type C60/ exTTF Diads and Triads
Su p p or tin g In for m a tion Ava ila ble: Synthetic procedures
and experimental data for 6, 8a -c, 9a -c, 10a -c, 11a , 15-
19, 20a -c, 21, and 22a -c. This material is available free of
charge via the Internet at http://pubs.acs.org.
Ack n ow led gm en t. This work has been supported
by DGSIC of Spain (Project BQU2002-00855). Part of
this work was supported by the Office of Basic Energy
Sciences of the U.S. Department of Energy (Contribu-
tion No. NDRL-4426 from the Notre Dame Radiation
Laboratory).
J O020412L
J . Org. Chem, Vol. 68, No. 3, 2003 791