Ground state electronic interactions in macrocyclic fullerene bis-adducts functionalized with bridging conjugated oligomers

Article abstract of DOI:10.1002/ejoc.200900830

Macrocyclic C₆₀-(π-conjugated oligomer) dyads have been prepared, from, the corresponding bis-malonates by a macrocyclization reaction on the C₆₀ sphere. In both multicomponent systems, the fullerene moiety and the π-conjugated oligo

Full text of DOI:10.1002/ejoc.200900830

FULL PAPER
DOI: 10.1002/ejoc.200900830
Ground State Electronic Interactions in Macrocyclic Fullerene Bis-Adducts
Functionalized with Bridging Conjugated Oligomers
Teresa M. Figueira-Duarte,[a] Vega Lloveras,[b] José Vidal-Gancedo,[b]
Béatrice Delavaux-Nicot,*[c] Carine Duhayon,[c] Jaume Veciana,*[b] Concepció Rovira,*[b]
and Jean-François Nierengarten*[a]
Dedicated to Professor Fritz Vögtle on the occasion of his 70th birthday
Keywords: Fullerenes / Conjugated oligomers / Electrochemistry / π-π interactions
Macrocyclic C60-(π-conjugated oligomer) dyads have been
prepared from the corresponding bis-malonates by a macro-
cyclization reaction on the C60 sphere. In both multicompo-
nent systems, the fullerene moiety and the π-conjugated
oligomer subunit are at the van der Waals contact due to the
cepting C60 spheroid, cyclic voltammetry revealed only small
changes in their redox potentials. However, these intramo-
lecular interactions have a significant influence on the elec-
tronic coupling of the two terminal aniline redox units of the
conjugated system in the dyads. Actually, when compared to
cyclic structure. Interestingly, the characteristic π-π* elec- the corresponding model compound 14·+, delocalization of
tronic transition band of the conjugated system is signifi-
cantly red-shifted in both dyads with respect to the corre-
sponding model compounds lacking the fullerene unit (∆λmax
= 24 to 34 nm). Whereas the absorption properties are dra-
matically affected by the intramolecular electronic interac-
tions between the conjugated bridging system and the ac-
the positive charge in the mixed-valence species derived
from the dyad 1 is more difficult due to the π-π interactions
of the conjugated system with the electron-withdrawing ful-
lerene group.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
solvent polarity on the deactivation pathways (electron
transfer vs. energy transfer) are well established,[3] the im-
portance of structural factors are not always well under-
stood. In particular, electronic interactions between the ful-
lerene and the conjugated oligomer fragment have been
stated for several dyads to explain their properties.[3–4] How-
ever, unambiguous experimental evidence for such interac-
tions is difficult to obtain, especially for hybrid systems in
which the two components are separated by a flexible
spacer. In order to clearly show the influence of π-π interac-
tions between the conjugated system and the fullerene moi-
ety on the electronic properties of C60-(π-conjugated oligo-
mer) dyads, we have designed compounds 1 and 2. In both
cases, by taking advantage of the peculiar structural fea-
tures of macrocyclic fullerene bis adducts, the bridging π-
conjugated oligomer unit and its fullerene partner are at
the van der Waals contact (see Figure S1 in the Supporting
Information). As a result, the absorption of the conjugated
oligomer in 1 and 2 is dramatically red-shifted when com-
pared to the corresponding model compounds lacking the
fullerene subunit. In addition, the electronic coupling be-
tween the two terminal N,N-dimethylaniline redox centers
is also influenced by the through-space intramolecular in-
teractions of the C60 units with the π-conjugated bridge.
Introduction
Hybrid systems combining C60 with π-conjugated oligo-
mers have shown a wide range of physical properties that
make them attractive candidates for a variety of interesting
applications in materials science.[1] Indeed, spectacular pho-
toactive systems associating fullerene moieties with π-con-
jugated donors have been described in the recent past.[1]
Their photophysical properties have been extensively
studied.[2] Whereas the influence of the donating ability of
the oligomer unit and of environmental factors such as the
[a] Laboratoire de Chimie des Matériaux Moléculaires, Université
de Strasbourg et CNRS (UMR 7509), Ecole Européenne de
Chimie, Polymères et Matériaux (ECPM),
25 rue Becquerel, 67087 Strasbourg Cedex 2, France
E-mail: nierengarten@chimie.u-strasbg.fr
[b] Institut de Ciència de Materials de Barcelona, Campus Uni-
versitari de Bellaterra and CIBER-BBN,
Cerdanyola 08193, Spain
E-mail: cun@icmab.es
vecianaj@icmab.es
[c] Laboratoire de Chimie de Coordination du CNRS,
205 route de Narbonne, 31077 Toulouse Cedex 4, France
E-mail: beatrice.delavaux-nicot@lcc-toulouse.fr
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.200900830.
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FULL PAPER
Results and Discussion
Scheme 1. Reagents and conditions: (i) PdCl2(PPh3)2, CuI, Et3N,
room temp. (79%); (ii) DIBAL-H, CH2Cl2, 0 °C (69%); (iii) DCC,
DMAP, HOBt, CH2Cl2, 0 °C to room temp. (91%); (iv) C60, DBU,
I2, PhMe, room temp. (19%).
Synthesis
The synthesis of fullerene derivative 1 is depicted in
Scheme 1. Compounds 3[5] and 4[6] were prepared according
to previously reported procedures. Dimethyl 2,3-dibro-
mofumarate (4) was subjected to a Pd-catalyzed cross-cou-
pling reaction[7] with 4-ethynyl-N,N-dimethylaniline (3) to
give 5 in 79% yield. Subsequent treatment with diiso-
butylaluminum hydride (DIBAL-H) in CH2Cl2 afforded
diol 6 in 69% yield. Reaction of 6 with carboxylic acid 7[8]
under esterification conditions using N,NЈ-dicyclohexyl-
carbodiimide (DCC), 4-(dimethylamino)pyridine (DMAP)
and 1-hydroxybenzotriazole (HOBt) gave bis-malonate 8 in
91% yield. Finally, fullerene derivative 1 was prepared by a
macrocyclization reaction at the C sphere with bis-malonate
8 under the reaction conditions developed in the group of
Diederich.[9] The C1-symmetric cis-2 bis-adduct 1 was thus
obtained in 19% yield.
Fullerene derivative 2 was prepared in 4 steps from build-
ing block 9[10] (Scheme 2). Pd-catalyzed cross-coupling re-
action of terminal alkyne 3 with bis-bromide 9 gave 10 in a
moderate yield (18%). Indeed, compound 9 was found to
be poorly reactive under Sonogashira conditions, most
probably due to negative steric effects resulting from the
presence of the bulky CH2OTIPS moieties in the ortho posi-
tion of the reactive bromide groups. However, sufficient
quantities of compound 10 were thus obtained and no par-
ticular efforts were made to improve its preparation. Treat-
ment of 10 with tetra-n-butylammonium fluoride (TBAF)
Scheme 2. Reagents and conditions: (i) 3, PdCl2(PPh3)2, CuI, PPh3,
THF, Et3N, 65 °C (18%); (ii) TBAF, THF, 0 °C (99%); (iii) 7, DCC,
DMAP, HOBt, CH2Cl2, 0 °C to room temp. (92%); (iv) C60, DBU,
I2, PhMe, room temp. (38%).
The structure and purity of compounds 1 and 2 were
1
in THF at 0 °C afforded compound 11 in a quantitative confirmed by H and 13C NMR spectroscopy, mass spec-
yield. Esterification of diol 11 with carboxylic acid 7 in the trometry and elemental analysis. For both macrocyclic bis
presence of DCC, HOBt and DMAP yielded bis-malonate adducts 1 and 2, the relative position of the two cycloprop-
12 (92%) from which the C1-symmetrical trans-4 bis-adduct ane rings on the C60 core (cis-2 for 1 and trans-4 for 2) was
2 was obtained in 38% yield by macrocyclization with C60. determined based on the molecular symmetry (C1 in both
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Ground State Electronic Interactions in Macrocyclic Fullerene Bis-Adducts
cases) deduced from their 1H and 13C NMR spectra. In N(2) distance was found to be 17.245 Å. The conjugated
both cases, the proposed addition pattern on the fullerene diethynylethene backbone of 14 is nearly perfectly planar
sphere is also in perfect agreement with the one of pre- but dihedral angles of ca. 19.7° [Ar–N(1)] and 42.9° [Ar–
viously reported fullerene bis adducts resulting from macro- N(2)] are observed for both terminal aromatic rings with
cyclization reactions of C60 with analogous tethered bis- respect to the diethynylethene plane. The peculiar orienta-
malonates.[9]
tion of these aromatic subunits can be explained by close
Finally, reference compounds 13 and 14 were prepared inspection of the packing. Indeed, this orientation allows
as shown in Scheme 3. Oligophenylene-ethynylene (OPE) the establishment of intermolecular edge-to-face π-π inter-
derivative 13 was obtained in 77% from 3 and 1,4-diiodo- actions between the neighboring para-disubstituted phenyl
benzene as described in the literature.[11] DCC-Mediated es- rings (Figure 1, B). Observation of the crystal lattice down
terification of diol 6 with AcOH afforded 14 in 82% yield the crystallographic axis b reveals a layered structure in
as a crystalline orange solid. Crystals suitable for X-ray which the conjugated backbone of the molecules is aligned
crystal-structure analysis were obtained by slow diffusion with axis c. Indeed, the 14 molecules are organized in co-
of hexane into a CHCl3 solution of 14. As shown in Fig- lumnar arrays parallel to the crystallographic axis a (Fig-
ure 1, X-ray crystallography unambiguously confirmed the ure 1, B). In this way, simultaneous intermolecular edge-to-
E-configuration of the alkene fragment in 14 and the N(1)– face π-π interactions of both phenyl units of 14 are possible
with the two aromatic rings of both neighboring 14 mole-
cules. Finally, it can be added that the aromatic rings of 14
giving rise to this intermolecular stacking are themselves in
π-π interactions in a face-to-edge manner with molecules
belonging to neighboring parallel columns (not shown).
Electronic Absorption Spectra
The absorption properties of compounds 1, 2, and of
their reference compounds 14 and 13 were investigated in
Scheme 3. Reagents and conditions: (i) 1,4-diodobenzene,
three different solvents, namely toluene, CH2Cl2 and THF.
As typical examples, the absorption spectra recorded for all
the compounds in CH2Cl2 solutions are reported in Fig-
ure 2. The UV/Vis spectra obtained for all compounds
show a strong absorption with a maximum between 360
and 440 nm which is assigned to the π-π* electronic transi-
tion of the conjugated system. For both 1 and 2, the ad-
ditional intense bands observed in the UV and the much
weaker features seen in the visible spectral region corre-
spond to the characteristic absorption of the fullerene chro-
mophore.
PdCl2(PPh3)2, CuI, Et3N, room temp. (77%); (ii) AcOH, DCC,
DMAP, HOBt, CH2Cl2, 0 °C to room temp. (82%).
Interestingly, the characteristic π-π* electronic transition
band of the conjugated system is significantly red-shifted in
1 with respect to model compounds 14 (∆λmax = 34 nm in
CH2Cl2). This red-shift between 1 and 14 was observed in
all the investigated solvents and found to be concentration
independent in the typical range for spectroscopic measure-
ments, i.e. 10–7–10–5 . Therefore it is only attributable to
through space intramolecular interactions occurring be-
tween the fullerene sphere and its bridging diethynylethene
unit. Importantly, the absorption spectrum of the C60-OPE
conjugate 2, relative to reference compound 13, shows the
same trend (Figure 2). As a result of the substantial ground
state interactions between the fullerene and the π-conju-
gated bridge, the absorption maximum of the OPE frag-
ment is bathochromically shifted by ca. 24 nm in 2 when
compared to reference compound 13. For both 1 and 2, the
HOMO–LUMO gap of the conjugated system is affected
by the π-π interactions with its neighboring electron-with-
drawing C60 unit. It is worth mentioning that red-shifts have
been reported for the porphyrin absorption in covalent and
Figure 1. (A) ORTEP plot of the structure of 14 (thermal elipsoids
are drawn at the 50% probability level). (B) Stacking within the 14
lattice (view down the crystallographic axis b) highlighting the
edge-to-face π-π interactions [a: C(22)H–C(11) 2.824 Å; b: C(23)
H–C(14) 2.864 Å; c: C(26)H–C(11) 3.055 Å; d: C(25)H–C(14)
2.943 Å].
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In the cathodic region, 1 and 2 give rise to a reduction
wave at –1.09 V vs. Fc/Fc+ corresponding to the first re-
duction of the fullerene. When compared to related fuller-
ene bis adducts,[15] the redox potential values obtained for
1 and 2 are only weakly affected by the intramolecular
π-π interactions between the fullerene moiety and the π-
conjugated oligomer. This is in line with previous observa-
tion on C60-porphyrin conjugates for which the redox po-
tentials of the fullerene-centered reductions are almost not
affected by its interaction with the porphyrin unit.[12] In
the anodic scan, all compounds show a two-electron pro-
cess attributed to the simultaneous oxidation of the two
N,N-dimethylaniline units suggesting weak electronic in-
teractions between the two redox centers. While the oxi-
dation of the bis(dimethylamino)-OPE derivatives 2 and
13 is irreversible, the oxidation process is reversible for 1
and 14 under these conditions. Comparison of the oxi-
dation potential of the N,N-dimethylaniline moieties in 14
and 13 with those obtained for 1 and 2 shows only a very
weak effect of the fullerene moieties (∆E = 30–40 mV).
Indeed, the oxidation process does not directly involve the
conjugated system but mainly takes place on the N atoms
of the terminal aniline subunits for which no specific
through-space intramolecular π-π interactions with the
C60 units are possible. For this reason, the oxidation of
the aniline groups is only weakly affected by the electronic
interactions between the conjugated bridging system and
the accepting C60 spheroid. However, these intramolecular
interactions should modulate the ability of the π-conju-
gated bridge to carry one electron from one aniline redox
unit to the other in the mono-oxidized compounds derived
from 1 and 2 as already demonstrated for fullerene-substi-
tuted mixed-valence bis(ferrocenylethynyl) ethene deriva-
tives.[16] Disappointingly, all attempts to perform stepwise
coulometric titration with 1, 2, 13, and 14 failed due to
the instability of the oxidized species.[17–18] Fortunately,
oxidized species derived from compounds 1 and 14 could
be generated chemically in THF/nitrobenzene (9:1) by ad-
dition of Fe(ClO4)3. Their formation was followed by ab-
sorption spectroscopy. Owing to the poor stability of the
oxidized species, it was necessary to add increasing
amounts of Fe(ClO4)3 to fresh solutions every time, and
to work under strictly anhydrous conditions and under ar-
gon. The evolution of the UV/Vis/NIR spectra of com-
pounds 1 and 14 during the chemical oxidation process is
shown in Figure 3.
Figure 2. Top: absorption spectra of 1 (black) and 14 (gray) in
CH2Cl2 at 298 K. Bottom: absorption spectra of 2 (black) and 13
(gray) in CH2Cl2 at 298 K.
non-covalent C60-porphyrin conjugates as a result of intra-
molecular π-stacking interactions between the two chromo-
phores.[12–13] Similar effects have also been described for
supramolecular complexes obtained from extended tetra-
thiafulvalene (ex-TTF) derivatives and C60.[14] It appears
that the characteristic signature of π-π interactions of the
fullerene unit with donors is a significant bathochromic
shift of the absorption bands of the donor moiety.
Electrochemical Properties
The electrochemical properties of compounds 1, 2, 13,
and 14 were investigated by cyclic voltammetry (CV). The
experiments were performed at room temperature in THF/
nitrobenzene (9:1) solutions containing tetra-n-butylammo-
nium hexafluorophosphate (0.1 ) as supporting electrolyte.
Potential data for all of the compounds are collected in
Table 1.
During the oxidation process of compounds 1 and 14 the
amine bands around 400 and 450 nm disappear and new
bands appear. The appearing band at 645 nm for 14 and
the shoulder at 604 for 1 increases upon increase of the
oxidant concentration and are assigned to the radical cation
of the amine.[18] More interesting is the weak and broad
band centered at 1626 and 1300 nm, for 1 and 14, respec-
tively, that appears and increases continuously until com-
plete formation of their mixed-valence compounds. After-
wards, the intensity of this band decreases until it disap-
pears when the dications 12+ and 142+ are completely
formed. This behavior is typical of an intervalence charge-
Table 1. Electrochemical properties of 1, 2, 13, and 14 determined
by cyclic voltammetry on a Pt working electrode in THF/nitroben-
zene (9:1) with 0.1  [(nBu4)N]PF6 at room temp.
Reduction
Oxidation
Compound
E1/2
E1/2
Epa
14
1
13
2
+0.35[a,b]
–1.09[a]
–1.09[a]
+0.38[a,b]
+0.38[b,c]
+0.42[b,c]
[a] Values for (Epa + Epc)/2 in V vs. Fc/Fc+ at a scan rate of
0.1 Vs–1. [b] Bielectronic process. [c] Irreversible process, Ep value
in V vs. Fc/Fc+ at a scan rate of 0.1 Vs–1.
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Ground State Electronic Interactions in Macrocyclic Fullerene Bis-Adducts
Figure 3. (A) Top: evolution of the UV/Vis/NIR spectra of compound 14 in THF/nitrobenzene (9:1) during the chemical oxidation
process by addition of increasing amounts of Fe(ClO4)3 in a fresh solution of 14 every time. Bottom, left: expanded spectra of the visible
region showing an isosbestic point. Bottom right: expanded spectra of the NIR region showing the increase of the intramolecular electron
transfer absorption band until the maximum when the mixed-valence species is completely formed. (B) Top: evolution of the UV/Vis/
NIR spectra of compound 1 in THF/nitrobenzene (9:1) during the chemical oxidation process by addition of increasing amounts of
Fe(ClO4)3 in a fresh solution of 1 every time. Bottom, left: expanded spectra of the visible region showing an isosbestic point. Bottom,
right: expanded spectra of the NIR region showing the increase of the intramolecular electron-transfer absorption band until a maximum
when the mixed-valence species is completely formed.
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transfer (IV-CT) band due to the presence of an intramolec- subunit. In contrast, cyclic voltammetry studies revealed
ular electron-transfer process in a Class II mixed-valence that the changes in redox potentials of one component due
compound.[19]
to the presence of the other one are small. Even if the oxi-
Along with the changes of these bands, the appearance dation of the aniline groups is weakly affected by the elec-
and maintenance of one well-defined isosbestic point for tronic interactions between the conjugated bridging system
both 1 (at 458 nm) and 14 (at 445 nm) indicates that in the and the fullerene moiety, these intramolecular interactions
used experimental conditions the formed mixed-valence have a significant influence on the electronic coupling of
species do not decompose (Figure 3).
the two aniline redox units in dyad 1. Actually, when com-
From the characteristics of the IV-CT band, the effective pared to model compound 14·+, delocalization of the posi-
electronic coupling Vab (in cm–1) between both aniline redox tive charge in 1·+ is made more difficult by the π-π interac-
centers can be determined, using Equation (1) developed by tions of the conjugated system with the electron-with-
Hush.[20]
drawing fullerene group. In conclusion, we have clearly
shown that the existence of π-π interactions between the
two components in C60-(π-conjugated oligomer) dyads can
be easily demonstrated by a significant bathochromic shift
of the absorption bands of the conjugated system. Changes
in redox potential are, however, quite weak, thus electro-
chemical data must be considered with care to demonstrate
the occurrence of electronic interactions in such systems.
(1)
In this equation ∆ν1/2 (in cm–1) is the half-height band
width of the IVCT band, R (in Å units) is the distance be-
tween the redox centres (here the distance between the two
nitrogen atoms, as determined by the X-ray structure of 14),
εmax (in –1 cm–1) is the maximum molar extinction coeffi-
cient, and νmax = (in cm–1) the wavenumber at the maximal
Experimental Section
˜
absorbance. Equation (1) gives an effective electronic cou-
pling (Vab) of 152 cm–1 for 1·+, and 291 cm–1 for 14·+ taking
into account the comproportionation constants to recalcu-
late the molar extinction coefficient. The spectroscopic data
of IV-CT bands obtained from the deconvolution (see Fig-
ures S2 and S3, Supporting Information) of the experimen-
tal spectra of 1·+ and 14·+ are summarized in Table 2.
General: Reagents and solvents were purchased as reagent grade
and used without further purification. Compounds 3,[5] 4,[6] 7,[8]
9,[10] and 13[11] were prepared according to the literature. THF was
distilled from sodium benzophenone ketyl. All reactions were per-
formed in standard glassware under an inert Ar atmosphere. Evap-
oration and concentration were done at water aspirator pressure
and drying in vacuo at 10–2 Torr. Column chromatography: silica
gel 60 (230–400 mesh, 0.040–0.063 mm) was purchased from E.
Merck and treated with Et3N (1% in CH2Cl2) for the purification
of compounds bearing NEt2 groups. Thin-layer chromatography
(TLC) was performed on glass sheets coated with silica gel 60 F254
purchased from E. Merck, visualization by UV light. IR spectra
(cm–1) were measured on an ATI Mattson Genesis Series FTIR
instrument. NMR spectra were recorded on a Bruker AC 300 with
solvent peaks as reference. UV/Vis/NIR spectra were taken on a
Varian Cary 5 E spectrophotometer. MALDI-TOF-mass spectra
were carried out on a Bruker BIFLEXTM matrix-assisted laser de-
sorption time-of-flight mass spectrometer equipped with
SCOUTTM High Resolution Optics, an X-Y multi-sample probe
and a gridless reflector. Ionization is accomplished with the 337 nm
beam from a nitrogen laser with a repetition rate of 3 Hz. All data
Table 2. Spectral data of the IV-CT bands obtained from the decon-
volution of the experimental spectra of 1·+ and 14·+ and calculated
Vab values.
νmax
/
εmax

/
∆ν1/2
/
RN–N
Å
/
V /
ab
cm–1
–1 cm–1
cm–1
cm–1
14·+
1·+
7700
6150
1700
592
4592
4468
17.245
17.245
291
152
The effective electronic coupling (Vab) value for 14·+ is
almost double the one found for 1·+ indicating that the elec-
tronic interactions between the two redox centres linked
with the same conjugated bridge are different. This behav-
iour is accounted for the through space intramolecular in- were acquired at a maximum accelerating potential of 20 kV in the
linear positive ion mode. The output signal from the detector was
digitized at a sampling rate of 1 GHz. A saturated solution of 1,8,9-
trihydroxyanthracene (dithranol from Aldrich, EC: 214-538-0) in
CH2Cl2 was used as a matrix. Typically, a 1:1 mixture of the sample
solution in CH2Cl2 was mixed with the matrix solution and 0.5 µL
of the resulting mixture was deposited on the probe tip.[21] Elemen-
tal analyses were performed by the analytical service at the Institut
Charles Sadron, Strasbourg. The cyclic voltammetric measure-
ments were performed on a 263A of EG&PAR potentiostat-gal-
vanostat. Electrochemical experiments were performed in a conven-
tional three-electrode cell consisting of platinum working and aux-
iliary electrodes and a Ag/AgNO3 reference electrode. The experi-
ments were carried out in ca. 10–3  solution of samples in THF/
nitrobenzene (9:1) containing 0.1  [(nBu4)N]PF6 (Fluka, Ն 99%
electrochemical grade) as supporting electrolyte. Before each mea-
surement, the solutions were degassed by bubbling argon for at
teraction between the π-conjugated bridge and the C60 unit
that generates an electrostatic field able to affect the
HOMO–LUMO gap of the conjugated wire.
Conclusions
Two macrocyclic dyads combining C60 with π-conjugated
oligomers have been prepared. Owing to their cyclic struc-
ture, the fullerene moiety and the π-conjugated oligomer
substituent are forced to be at the van der Waals contact in
both multicomponent systems. As a result, dramatic
changes are observed in the absorption properties of both
dyads. In particular, the absorption of the conjugated oligo-
mer moiety is significantly red-shifted when compared to
the corresponding model compounds lacking the fullerene least 5 min and the working electrode was burned to clean it. The
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Ground State Electronic Interactions in Macrocyclic Fullerene Bis-Adducts
cyclic voltammograms were recorded under argon, at room tem-
perature at a scan rate of 0.1 Vs–1. Under these experimental condi-
tions, Fc+/Fc is observed at 0.58 V vs. Ag/AgNO3.
144.0, 143.5, 143.4, 143.3, 143.0, 142.95, 142.9, 142.85, 142.8,
142.75, 142.3, 140.9, 140.0, 137.3, 136.9, 136.8, 136.75, 136.7,
136.1, 135.9, 135.4, 133.7, 133.3, 127.2, 126.9, 111.9, 111.7, 109.55,
109.5, 106.8, 106.7, 105.9, 104.5, 101.5, 101.4, 88.0, 86.3, 68.4, 68.3,
68.1, 68.0, 67.3, 67.0, 66.7, 66.6, 50.0, 49.7, 40.2, 40.1, 31.9, 29.7,
29.6, 29.45, 29.4, 29.3, 26.1, 22.7, 14.1 ppm. MALDI-TOF-MS:
2180.3 (M+, calcd. for C152H134O12N2: 2180.74). C152H134N2O12·
CH2Cl2 (2265.68): calcd. C 81.11, H 6.05, N 1.24; found C 81.55,
H 6.16, N 1.18.
Compound 5:
A mixture of 3 (0.6 g, 4.15 mmol), 4 (0.5 g,
1.66 mmol), PdCl2(PPh3)2 (280 mg, 0.39 mmol) and CuI (150 g,
0.79 mmol) in dry Et3N (10 mL) was stirred at room temperature
under argon for 12 h. The solution was concentrated, taken up in
CH2Cl2 and filtered through a Celite pad. The organic phase was
washed with H2O, dried with MgSO4 filtered and the solvents evap-
orated to dryness. Column chromatography (SiO2, CH2Cl2/hexane,
Compound 10: As described for 5, with 3 (0.2 g, 1.38 mmol), 9
(0.28 g, 0.46 mmol), PdCl2(PPh3)2 (65 mg, 0.09 mmol), CuI (7 mg,
7:3) yielded
5
(0.56 g, 79%). Dark red powder. 1H NMR
(300 MHz, CDCl3): δ = 7.39 (d, J = 7 Hz, 4 H, Ar-H), 6.62 (d, J 0.04 mmol) and PPh3 (18 mg, 0.07 mmol) in THF/Et3N (3:1)
= 7 Hz, 4 H, Ar-H), 3.91 (s, 6 H, OCH3), 3.00 [s, 12 H, N(CH3)2] (4 mL). Two successive column chromatographies (SiO2, CH2Cl2/
ppm. C26H26N2O4 (430.50): calcd. C 72.54, H 6.09, N 6.51; found
C 72.50, H 6.22, N 6.30.
hexane, 1:1) yielded 10 (0.06 g, 18%) as a yellow powder. 1H NMR
(300 MHz, CD2Cl2): δ = 7.68 (s, 2 H, Ar-H), 7.40 (d, J = 8 Hz, 4
H, Ar-H), 6.71 (d, J = 8 Hz, 4 H, Ar-H), 5.07 (s, 4 H, Ar-CH2),
3.03 [s, 12 H, N(CH3)2], 1.18 [m, 42 H, Si(iPr)3] ppm.
C46H68O2N2Si2 (737.23).
Compound 6: A 1.0  solution of DIBAL-H in hexane (1.8 mL,
1.8 mmol) was slowly added to a solution of 5 (150 mg, 0.35 mmol)
in CH2Cl2 (5 mL) at 0 °C. The resulting mixture was stirred for 2 h.
After 4 h, MeOH was added, then water. The resulting mixture was
filtered through Celite and the solvents evaporated. Recrystaliz-
Compound 11: A 1.0  solution of TBAF in THF (0.25 mL,
0.25 mmol) was added to
a stirred solution of 10 (0.06 g,
ation from CH2Cl2/MeOH yielded 6 (90 mg, 69%). Orange powder. 0.08 mmol) in THF (5 mL) at 0 °C under argon. After 4 h, the
1H NMR (300 MHz, CDCl3): δ = 7.34 (d, J = 7 Hz, 4 H, Ar-H),
6.66 (d, J = 7 Hz, 4 H, Ar-H), 4.55 (s, 4 H, CH2), 3.00 [s, 12 H,
N(CH3)2] ppm. C24H26O2N2 (374.48).
solution was concentrated and taken up in CH2Cl2. The organic
layer was washed with H2O, dried with MgSO4, filtered and the
solvents evaporated to dryness. Column chromatography (SiO2,
CH2Cl2) yielded 11 (34 mg, 99%) as a yellow powder. 1H NMR
(300 MHz, CD2Cl2): δ = 7.60 (s, 2 H, Ar-H), 7.43 (d, J = 8 Hz, 4
H, Ar-H), 6.71 (d, J = 8 Hz, 4 H, Ar-H), 4.89 (s, 4 H, Ar-CH2),
3.03 [s, 12 H, N(CH3)2] ppm. C28H28O2N2 (424.54).
Compound 8: DCC (0.18 g, 0.89 mmol) was added to a solution of
6
(0.14 g, 0.37 mmol), 7 (0.53 g, 0.93 mmol), HOBt (23 mg,
0.15 mmol) and DMAP (18 mg, 0.15 mmol) in CH2Cl2 (15 mL) at
0 °C. After 1 h, the mixture was allowed to slowly warm to room
temperature. After 12 h, the mixture was filtered and the solvents
evaporated. Column chromatography (SiO2, CH2Cl2) yielded 8
(0.5 g, 91%). Orange glassy product. 1H NMR (300 MHz, CDCl3):
δ = 7.30 (d, J = 7 Hz, 4 H, Ar-H), 6.58 (d, J = 7 Hz, 4 H, Ar-H),
6.45 (d, J = 2 Hz, 4 H, Ar-H), 6.38 (t, J = 2 Hz, 2 H, Ar-H), 5.12
(s, 4 H, ArCH2), 5.07 (s, 4 H, C=C-CH2), 3.90 (t, J = 6 Hz, 8 H,
Compound 12: As described for 8, with DCC (40 mg, 0.19 mmol),
11 (34 mg, 0.08 mmol),
7 (0.12 g, 0.2 mmol), HOBt (5 mg,
0.03 mmol) and DMAP (4 mg, 0.03 mmol) in CH2Cl2 (10 mL).
Column chromatography (SiO2, CH2Cl2) yielded 12 (0.11 g, 92%)
as a yellow powder. 1H NMR (300 MHz, CDCl3): δ = 7.52 (s, 2 H,
Ar-H), 7.38 (d, J = 8 Hz, 4 H, Ar-H), 6.63 (d, J = 8 Hz, 4 H, Ar-
OCH2), 3.52 [s, 4 H, CH2(C=O)2], 2.97 [s, 12 H, N(CH3)2], 1.73 H), 6.45 (d, J = 2 Hz, 4 H, Ar-H), 6.38 (t, J = 2 Hz, 2 H, Ar-H),
(m, 8 H, OCH2CH2), 1.50–1.26 (m, 72 H, CH2), 0.87 (t, J = 7 Hz, 5.40 (s, 4 H, Ar-CH2), 5.10 (s, 4 H, Ar-CH2), 3.88 (t, J = 6 Hz, 8
12 H, CH2CH3) ppm. 13C NMR (75 MHz, CDCl3): δ = 166.2, H, OCH2), 3.52 [s, 4 H, CH2(C=O)2], 2.99 [s, 12 H, N(CH3)2], 1.75
160.4, 137.3, 132.9, 111.9, 106.3, 101.2, 68.1, 67.2, 65.3, 41.4, 40.2,
31.9, 29.7, 29.65, 29.6, 29.55, 29.4, 29.3, 29.25, 26.0, 22.7,
14.1 ppm. C92H138N2O12 (1464.11): calcd. C 75.47, H 9.50, N 1.91;
found C 75.66, H 9.66, N 1.90.
(m, 8 H, OCH2CH2), 1.50–1.25 (m, 72 H, CH2), 0.88 (t, J = 7 Hz,
12 H, CH2CH3) ppm. 13C NMR (75 MHz, CDCl3): δ = 166.2,
166.2, 160.4, 150.3, 137.2, 135.9, 132.8, 131.2, 122.5, 111.7, 109.2,
106.2, 101.2, 97.9, 84.4, 68.0, 67.1, 65.2, 41.4, 40.1, 31.9, 29.6, 29.6,
29.4, 29.35, 29.2, 26.0, 22.7, 14.1 ppm. C96H140N2O12 (1514.17):
calcd. C 76.15, H 9.32, N 1.85; found C 76.19, H 9.56, N 1.55.
Compound 1: DBU (0.21 mL, 1.36 mmol) was added to a solution
of C60 (0.25 g, 0.34 mmol), I2 (0.19 g, 0.75 mmol) and 8 (0.5 g,
0.34 mmol) in toluene (500 mL) at room temperature under argon.
The solution was stirred for 12 h, filtered through a short plug of
SiO2 and concentrated. Column chromatography (SiO2, CH2Cl2/
hexane, 1:1) followed by gel permeation chromatography (Biorad,
Compound 2: As described for 1, with C60 (52 mg, 0.07 mmol), 12
(0.105 g, 0.07 mmol) DBU (0.05 mL, 0.28 mmol) and I2 (39 mg,
0.15 mmol) in toluene (250 mL) Column chromatography (SiO2,
CH2Cl2/hexane, 1:1) followed by gel permeation chromatography
(Biorad, Biobeads SX1, CH2Cl2) gave 2 (60 mg, 38%) as a brown
Biobeads SX1, CH2Cl2) gave 1 (0.14 g, 19%). Brown glassy prod-
1
uct. H NMR (300 MHz, CDCl3): δ = 7.51 (d, J = 7 Hz, 2 H, Ar- glassy product. 1H NMR (300 MHz, CDCl3): δ = 7.61 (s, 1 H, Ar-
H), 7.37 (d, J = 7 Hz, 2 H, Ar-H), 6.67 (d, J = 7 Hz, 2 H, Ar-H),
H), 7.36 (d, J = 8 Hz, 2 H, Ar-H), 7.34 (s, 1 H, Ar-H), 7.32 (d, J
6.47 (d, J = 7 Hz, 2 H, Ar-H), 6.45 (d, J = 2 Hz, 2 H, Ar-H), 6.41 = 8 Hz, 2 H, Ar-H), 6.63 (broad s, 4 H, Ar-H), 6.60 (d, J = 8 Hz,
(d, J = 2 Hz, 2 H, Ar-H), 6.35 (t, J = 2 Hz, 1 H, Ar-H), 6.29 (t, J 2 H, Ar-H), 6.57 (d, J = 11 Hz, 1 H, Ar-CH), 6.54 (d, J = 8 Hz, 2
= 2 Hz, 1 H, Ar-H), 6.18 (d, J = 11 Hz, 1 H, C=C-CH), 5.55 (d, J H, Ar-H), 6.46 (t, J = 2 Hz, 1 H, Ar-H), 6.45 (t, J = 2 Hz, 1 H,
= 11 Hz, 1 H, C=C-CH), 5.33 (d, J = 11 Hz, 1 H, Ar-CH), 5.27 Ar-H), 5.91 (d, J = 11 Hz, 1 H, Ar-CH), 5.48 (d, J = 11 Hz, 1 H,
(AB, J = 11 Hz, 2 H, Ar-CH2), 5.11 (d, J = 11 Hz, 1 H, Ar-CH), Ar-CH), 5.46 (s, 2 H, Ar-CH2), 5.44 (s, 2 H, Ar-CH2), 4.98 (d, J =
4.75 (d, J = 11 Hz, 1 H, C=C-CH), 3.83 (m, 8 H, OCH2), 3.02 [s, 11 Hz, 1 H, Ar-CH), 3.96 (t, J = 6 Hz, 4 H, OCH2), 3.93 (t, J =
6 H, N(CH3)2], 2.89 [s, 6 H, N(CH3)2], 1.70 (m, 8 H OCH2CH2),
6 Hz, 4 H, OCH2), 2.97 [s, 6 H, N(CH3)2], 2.95 [s, 6 H, N(CH3)2],
1.50–1.26 (m, 72 H, CH2), 0.88 (t, J = 7 Hz, 12 H, CH2CH3) ppm. 1.74 (m, 8 H, OCH2CH2), 1.50–1.24 (m, 72 H, CH2), 0.87 (t, J =
13C NMR (75 MHz, CDCl3): δ = 162.8, 162.7, 162.5, 161.8, 160.35, 7 Hz, 12 H, CH2CH3) ppm. 13C NMR (75 MHz, CDCl3): δ =
160.3, 150.8, 150.5, 148.9, 148.2, 147.4, 147.35, 147.25, 147.2, 164.2, 163.9, 163.85, 163.4, 160.5, 150.4, 150.35, 148.1, 146.9,
145.9, 145.85, 145.8, 145.75, 145.65, 145.6, 145.5, 145.3, 145.3,
146.8, 146.7, 146.4, 146.3, 145.9, 145.8, 145.5, 145.4, 145.3, 145.25,
145.0, 144.95, 144.9, 144.85, 144.6, 144.55, 144.4, 144.1, 144.05, 145.2, 145.1, 145.05, 145.0, 144.95, 144.7, 144.6, 144.5, 144.4,
Eur. J. Org. Chem. 2009, 5779–5787
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5785

B. Delavaux-Nicot, J. Veciana, C. Rovira, J.-F. Nierengarten et al.
FULL PAPER
144.3, 144.1, 143.9, 143.4, 143.0, 142.95, 142.9, 142.8, 142.75, la Recherche (Solaire Photovoltaïque – Nanorgysol), the Spanish
142.6, 142.5, 142.2, 142.1, 141.9, 141.85, 141.8, 141.7, 141.6, 141.4, Dirección General de Investigación (DGI) (project EMOCIONa,
141.3, 141.2, 141.15, 141.1, 140.7, 140.3, 140.25, 139.7, 139.3, CTQ2006-06333/BQU), the European Science Foundation (ESF)
136.7, 136.65, 136.4, 136.1, 134.9, 134.4, 132.9, 132.85, 132.7, (EUROCORES-SONS “FUNSmarts II” project) and the Instituto
132.6, 132.2, 125.4, 124.6, 111.75, 111.7, 109.2, 109.15, 106.7, de salud Carlos III, MIyC, through “Acciones CIBER”.
106.3, 101.8, 101.7, 99.3, 98.2, 84.8, 84.4, 68.7, 68.6, 68.2, 68.14,
66.7, 66.1, 40.1, 31.9, 29.7, 29.6, 29.45, 29.35, 29.3, 26.1, 22.7, 14.2
ppm. MALDI-TOF-MS: 2230.6 (M+, calcd. for C156H136O12N2: [1] J. L. Segura, N. Martin, D. M. Guldi, Chem. Soc. Rev. 2005,
34, 31–47.
2230.80). C156H136N2O12 (2230.80): calcd. C 83.99, H 6.14, N 1.26;
found C 83.70, H 6.36, N 1.19.
[2] T. M. Figueira-Duarte, A. Gégout, J.-F. Nierengarten, Chem.
Commun. 2007, 109–119.
Compound 14: As described for 8, with 6 (90 mg, 0.24 mmol),
AcOH (0.04 mL, 0.6 mmol), DCC (0.12 g, 0.58 mmol), HOBt
(15 mg, 0.1 mmol) and DMAP (12 mg, 0.1 mmol) in CH2Cl2
(10 mL) Column chromatography (SiO2, hexane/CH2Cl2, 1:1)
yielded 14 (0.09 g, 82%) as orange crystals. 1H NMR (300 MHz,
CDCl3): δ = 7.32 (d, J = 8 Hz, 4 H, Ar-H), 6.62 (d, J = 8 Hz, 4 H,
Ar-H), 5.05 (s, 4 H, CH2), 2.99 [s, 12 H, N(CH3)2], 2.14 (s, 6 H,
CH3) ppm. 13C NMR (75 MHz, CDCl3): δ = 170.8, 150.4, 132.7,
125.3, 111.7, 109.2, 103.4, 84.3, 64.5, 40.1, 20.9 ppm. FAB-MS:
458.1 (M+, calcd. for C28H30O4N2: 458.22). C28H30N2O4 (458.56):
calcd. C 73.34, H 6.59, N 6.11; found C 73.55, H 6.70, N 5.98.
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X-Ray Crystal Structure of 14: Crystals suitable for X-ray crystal-
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a CH2Cl2 solution of 14. Data were collected at 180 K on an IPDS
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¯
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Acknowledgments
This research was supported by the Centre National de la Recher-
che Scientifique (CNRS) (UMR 7509), the Agence Nationale de
5786
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Received: July 23, 2009
Published Online: October 8, 2009
Eur. J. Org. Chem. 2009, 5779–5787
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5787