Fullerene-containing liquid-crystalline dendrimers

Article abstract of DOI:10.1039/b103798f

Addition reaction of mesomorphic malonate-based dendrimers (up to the fourth generation) with C₆₀ gave liquid-crystalline fullerene derivatives. The cyanobiphenyl unit was used as liquid-crystalline promoter. The malonates presented nematic and

Full text of DOI:10.1039/b103798f

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Fullerene-containing liquid-crystalline dendrimers{
a
Blaise Dardel, Daniel Guillon,* Benoıt Heinrich and Robert Deschenaux*
b
b
a
ˆ
aInstitut de Chimie, Universite´ de Neuchaˆtel, Avenue de Bellevaux 51, Case postale 2, CH-
2007 Neuchaˆtel, Switzerland. Fax: z41 32 718 25 11; E-mail: robert.deschenaux@unine.ch
bInstitut de Physique et Chimie des Mate´riaux de Strasbourg, Groupe des Mate´riaux
Organiques, 23 Rue du Loess, 67037 Strasbourg Ce´dex, France
Received 26th April 2001, Accepted 30th May 2001
First published as an Advance Article on the web 1st October 2001
Addition reaction of mesomorphic malonate-based dendrimers (up to the fourth generation) with C60 gave
liquid-crystalline fullerene derivatives. The cyanobiphenyl unit was used as liquid-crystalline promoter. The
malonates presented nematic and/or smectic A phases. The fullerenes showed only smectic A phases, with the
exception of the second generation dendrimer for which smectic A and nematic phases were observed. The
supramolecular organization of the fullerene-based molecular units within the smectic A layers was investigated
by X-ray diffraction. Two structural regimes were determined. For the low generation dendrimers, the
supramolecular organization is determined by steric factors. For the high generation dendrimers, the mesogenic
groups impose a microphase organization: due to lateral extension of the branching part of the molecule, the
cyanobiphenyl groups arrange in a parallel fashion as in classical smectic A phases, the rest of the
macromolecule being located between the mesogenic sublayers.
cyanobiphenyl (for the hexa-adduct derivative18) units were
Introduction
used as liquid-crystalline promoters. The fullerenes displayed
smectic A phases. Recently, we reported the first liquid-
crystalline fulleropyrrolidine.19 The latter was prepared by 1,3-
dipolar cycloaddition from a mesomorphic aldehyde derivative
and sarcosine to C60 by following well-established literature
procedures.20 The fullerene derivative displayed a smectic A
phase. Undoubtedly, the functionalization of C60 with liquid-
crystalline addends is a suitable method for the elaboration of
fullerene-containing thermotropic liquid crystals.
Owing to its size and shape, C60 decreases the liquid-
crystalline tendency of the addend: C60 acts as a bulky spacer
between the molecular units. This behavior could be circum-
vented either by carrying out a hexa-addition18 or by using a
second generation dendritic addend.17,19,21 In both cases, the
large number of mesogenic groups compensated the influence
of C60.
The use of dendritic addends could be an interesting means
for the elaboration of fullerene-containing liquid crystals with
tailor-made properties. The properties could be controlled via
the dendrimer generation. Obviously, the influence of C60
on the thermal and mesomorphic behavior for a series of
homologous dendritic materials has to be understood for the
elaboration of materials displaying desired properties.
We report, herein, the synthesis, characterization, liquid-
crystalline properties and supramolecular organization of a
homologous family of fullerene-containing thermotropic
liquid-crystals obtained from mesomorphic dendritic malo-
nates (up to the fourth generation). The dendrimers were
prepared by applying a convergent synthetic methodology.22
Non-dendritic materials were also synthesized and used as
model compounds. The cyanobiphenyl framework was used as
liquid-crystalline promoter.
The covalent functionalization of the [60]fullerene (C60) with
dendritic addends was first reported by Fre´chet et al. and
proved to be an elegant and effective method for the design of
C
60 derivatives with polymer properties.1 After this pioneering
work, other fullerene-based dendrimers were prepared and led
to enthusiastic studies in supramolecular chemistry, materials
science and medicinal chemistry: 1) a dendritic addend
containing carboxylic acid functions was used to solubilize
C60 in water,2 2) the modification of C60 with hydrophilic
dendrons led to amphiphilic fullerenes which gave rise to stable
Langmuir and Langmuir–Blodgett films,3,4 and membranes,5
3) chiral6 or non-chiral7 dendritic hexa-adducts of fullerenes
were obtained by functionalizing C60 with two different
addends, and 4) globular dendrimers containing the porphyrin
chromophore were designed to mimic natural metalloproteins.8
In the above-mentioned examples, C60 is located at the center
of the molecule. Nierengarten9 reported fullerene-based
dendrimers in which C60 is situated either at the periphery10
or at the branching points11 of the dendrimers. This approach
is interesting for the elaboration of fullerene-rich materials.12
Finally, non-covalent supramolecular complexes, obtained
from C60 and various polybenzyl ether dendrimers, were
reported.13
We are interested in fullerene-containing thermotropic liquid
crystals. Two objectives motivate this research: 1) the under-
standing of how a sphere-like structure can be incorporated
into liquid-crystalline phases (this study will lead to a better
understanding of the structure–organization relationship for
fullerene-based supramolecular assemblies), and 2) the design
of new anisotropic materials.
The first concept we developed for the elaboration of
liquid-crystalline fullerenes, addition of mesomorphic malo-
nates to C60 by adapting the Bingel reaction,14 led to a variety
of liquid-crystalline mono- and hexa-adduct derivatives.15–18
The cholesterol (for the mono-adduct derivatives15–17) and
Results and discussion
Design
This study is based on three types of structures: i) the model
compounds 1 and 2 (Fig. 1), ii) the dendritic structures 3–6
{Basis of a presentation given at Materials Discussion No. 4, 11–14
September 2001, Grasmere, UK.
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DOI: 10.1039/b103798f

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Fig. 1 Structures of model compounds 1 and 2.
(Fig. 2) and iii) the hemi-dendritic structures 7 and 8 (Fig. 3).
These compounds were designed to emphasize i) the influence
of the number of alkyl chains included in the mesomorphic
promoter (two chains in 1 and four chains in 2), and ii) the
influence of the dendrimer generation (3 and 7: first generation,
4 and 8: second generation, 5: third generation, 6: fourth
generation) on the thermal and liquid-crystalline properties.
Note that the generation number 0 is assigned to the model
compound 2.
corresponding malonate, which was used in the addition
reaction with C60. In ref. 23, 18 was used in an elegant
convergent synthesis of aryl ester dendrimers.
The deprotection of the silyl group depended on the quality
of Zn(BF4)2 used. If the reaction does not proceed at room
temperature as carried out here (see Experimental section), it
can be conducted at 50–60 uC.24
The synthesis of hemi-dendrimers 7 (Scheme 8) and 8
(Scheme 9) required the preparation of 33 (Scheme 8) which
was obtained by condensation of ethyl malonyl chloride (31)
with 32.25 Esterification of the latter with either 20 or 23 gave
malonate derivatives 34 and 35, respectively, which were used
in the addition reaction with C60.
The structure and purity of all of the compounds were
1
confirmed by H NMR spectroscopy and elemental analysis.
The 13C NMR spectra were recorded only up to the first
dendrimer generation; from the second generation dendrimer,
13C NMR analysis would have required too large amounts of
materials.
The fullerene and malonate derivatives showed similar 1H
NMR spectra (see Experimental section). The malonates gave
an additional signal arising from the RO2C–CH2–CO2R group.
The UV–vis spectra of the fullerenes (see Experimental section)
are in agreement with the [6,6]-closed methanofullerene
structure.26 The spectrum of dendrimer 6 is shown as a
representative example in Fig. 4. The fullerenes retained the
solubility properties of the malonates and were found to be
soluble in common organic solvents.
Syntheses
The preparation of 1–8 required the synthesis of the correspond-
ing malonate followed by the addition of the malonate to C60
in the presence of I2 and 1,8-diazabicyclo[5.4.0]undec-7-ene
(DBU). Scheme 1 shows the synthesis of the liquid-crystalline
promoter 9. Treatment of 10-bromodecanol (10) with 4-hydro-
xybenzoic acid (11) gave intermediate 12, the carboxylic acid
function of which was esterified with 4-hydroxycyanobiphenyl
(13) to give 9.
The synthesis of 1 is presented in Scheme 2. Condensation of
9 with malonyl chloride (14) gave malonate derivative 15.
Addition of the latter to C60 furnished 1.
The synthesis of 2 is illustrated in Scheme 3. Esterification of
diacid 16 17 with 9 gave malonate 17, the addition of which to
C60 led to 2.
The synthesis of the first generation dendrimer 3 is depicted
in Scheme 4. Esterification of diacid 18 23 with 9 gave protected
branch 19. Removal of the silyl protecting group with Zn(BF4)2
gave phenol intermediate 20, which was condensed with 16 17 to
give malonate 21. Addition of 21 to C60 furnished 3.
Liquid-crystalline behavior
The synthesis of the second generation dendrimer
4
The liquid-crystalline and thermal properties of the meso-
morphic promoter, malonate derivatives and fullerene deriva-
tives were investigated by a combination of polarized optical
miscroscopy (POM) and differential scanning calorimetry
(DSC). The phase transition temperatures and enthalpy
changes are reported in Table 1. The mesomorphic behavior
of the phenol and silyl intermediates was not examined. Their
(Scheme 5), third generation dendrimer 5 (Scheme 6) and
fourth generation dendrimer 6 (Scheme 7) is based on the
convergent growth of the intermediate phenol derivative, which
is prepared by reacting diacid 18 23 with the phenol obtained
from the preceding dendrimer generation, followed by the
deprotection of the silyl substituent with Zn(BF4)2. Esterifica-
tion of the phenol derivative with diacid 16 17 gave the
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Fig. 2 Structures of dendrimers 3–6. For R, see Fig. 1.
melting (Tm) and/or clearing (Tc) points are reported in the
Experimental section.
The cyanobiphenyl derivative 9 gave a nematic phase.
The malonates gave rise to nematic (21), smectic A (27, 30
and 35) or smectic A and nematic (15, 17, 24 and 34) phases.
Model compound 15 gave a higher clearing point than model
compound 17. This is the consequence of the additional chains
in 17 which add flexibility. For the dendritic compounds, the
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Fig. 3 Structures of hemi-dendrimers 7 and 8.
stability of the liquid-crystalline state increased with the
dendrimer generation: the higher the number of mesomorphic
units, the higher the isotropization temperature. The hemi-
dendrimers 34 and 35 also followed this trend.
Two features encountered for the malonates were found for
the fullerene derivatives: compound 1, with two flexible chains,
showed a higher clearing point than 2 having four flexible
chains, and the clearing point increased with the dendrimer
generation.
A striking difference between the fullerenes and the
malonates of low generation resides in the liquid-crystalline
phases which were observed: the fullerene derivatives exhibited
only smectic A phases, with the exception of the second
generation dendrimer 4, which showed nematic and smectic A
phases. This result is an indication that the sphere-like C60 unit
governs, at least in part, the supramolecular organization of the
mesomorphic units within the liquid-crystalline state. This
behavior is clearly emphasized by comparing the mesomorphic
behavior of malonate 21 (nematic phase) with that of its
fullerene analogue 3 (smectic A phase). Finally, the fullerene
derivatives gave clearing points which were lower than those of
their malonate analogues.
The liquid-crystalline phases were identified by POM on the
basis of their optical textures (nematic phase: homeotropic and
schlieren textures; smectic A phase: homeotropic and focal
conic textures). The narrow nematic phase displayed by 4 was
clearly detected by DSC (Fig. 5). From the second dendrimer
generation, glass transitions were recorded by DSC. This is in
agreement with the non-crystalline character of the materials.
Supramolecular organization
To describe the molecular organization within the smectic A
layers, it is necessary to take into account, at least for the low
generation dendrimers and for an efficient space filling, the fact
that the fullerene moiety has a cross-sectional area of about
2 27
90–100 A , whereas the mesogenic group has a cross-
˚
2 28
sectional area of about 22–25 A . In addition to these steric
˚
constraints, the molecular organization may be driven by
specific interactions, such as: i) strong attractions between the
fullerene moieties which could result in aggregation of the C60
units, ii) dipolar interactions through the strong terminal dipole
moments of the mesogenic groups or iii) the natural tendency
of the mesogenic groups to form an anisotropic organization
within micro-domains. Finally, the amphipathic nature of these
macromolecules can also be considered, resulting in micro-
segregation of the polarizable and non-polarizable parts.
The X-ray diffraction patterns registered for all of the
compounds are characteristic of smectic A phases. They
contain, in the low angle region, two sharp reflections, the
corresponding spacing of which is in the 1 : 2 ratio, and, in the
wide angle region, a diffuse signal corresponding to the liquid-
like arrangement of the mesogenic groups. For comparison
purposes, all the d-layer spacings (in the smectic A phase) were
Scheme 1 Reagents and conditions: i, aqueous NaOH, EtOH, reflux,
66%; ii, 4-(dimethylamino)pyridine (DMAP), N,N’-dicyclohexylcarbo-
diimide (DCC), CH2Cl2, room temperature, 81%.
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Scheme 2 Reagents and conditions: i, Et3N, CH2Cl2, room temp., 92%; ii, C60, I2, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), toluene, room
temperature, 22%.
determined at 140 uC. The variation of the layer thickness as
a function of the generation number is represented in Fig. 6.
˚
Starting from values around 80 A for the low generation
dendrimers, the layer spacing decreases, and reaches a value of
conformers. The value of the layer spacing observed is in
agreement with the molecular dimensions (Fig. 8). The
interdigitation is not complete, due to the volume occupied
by the folded spacers close to the fullerene moiety. The diffuse
˚
about 55 A for the high generation dendrimers. Two regimes
can be distinguished: the first one corresponds to spacings
˚
around 75–80 A (for the low generation dendrimers), and the
˚
band around 9 A is attributed to lateral interactions between
pairs of mesogenic groups.
As for 1, in which the length of the arm attached to the
˚
second one corresponds to spacings around 55–60 A (for the
˚
malonate group is shorter by 15 A when compared to 2, the
˚
measured layer spacing is 57 A. This value indicates that 1
organizes as 2. Therefore, the supramolecular organizations of
1 and 2 within the smectic A layers are similar, and are mainly
driven by steric considerations.
high generation dendrimers). To understand this behavior, let
us consider the supramolecular organization of each of the
compounds within the smectic A phase.
Compound 2 (zeroth generation dendrimer, n~0). The X-ray
pattern of compound 2 is shown in Fig. 7. In addition to the
reflections described above, it is interesting to note the presence
Compound 3 (first generation dendrimer, n~1). The layer
˚
spacing is 82 A. This rather high value is, however, smaller than
˚
that expected for a pure double layer (105 A) formed through
˚
of a diffuse band corresponding to a spacing of 8.5–9 A. The
˚
layer spacing determined is 76 A. The molecular organization
dipolar interactions of the cyano groups attached at the end of
the mesogenic parts (like, for example, in the SA2 phase of low
molecular weight cyano compounds29). If we consider that the
two spacers attached directly onto the malonate group tend to
be parallel, a tentative explanation can be found in the
molecular simulation of the molecule (Fig. 9): the molecule
adopts a V-shape (the arms of the V being constituted by pairs
within the smectic A layers is essentially governed by steric
considerations, i.e. the necessary adequacy between the cross-
sections of C60 and that of several mesogenic groups. Thus, the
model proposed is based on the fact that the two arms of the
molecule are folded towards the same direction and then the
structure consists of a head-to-tail arrangement of such
Scheme 3 Reagents and conditions: i, 4-(dimethylamino)pyridinium toluene-p-sulfonate (DPTS), DCC, 4-pyrrolidinopyridine (4-PPy), CH2Cl2, 0 uC
and then room temperature, 51%; ii, C60, I2, DBU, toluene, room temperature, 50%.
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Scheme 6 Reagents and conditions: i, DPTS, DCC, 4-PPy, CH2Cl2, 0 uC and then room temperature, 100%; ii, Zn(BF4)2, H2O, THF, room
temperature, 95%; iii, DPTS, DCC, 4-PPy, CH2Cl2, 0 uC and then room temperature, 65%; iv, C60, I2, DBU, toluene, room temperature, 24%. For
R, see Fig. 1.
of mesogenic groups), leaving enough space for mesogenic
groups from adjacent layers to be included. Thus, a rather good
space filling, due to the reasonable fit between the cross-sectional
areas of fullerene and mesogenic groups, is achieved (Fig. 10).
to the branching part which begins to have significant lateral
extension with respect to the normal to the layers, i.e. to the
main orientation of the molecular axes of the mesogenic groups
(Fig. 11). Such a lateral extension is due to the chemical
structure itself, which allows free space between mesogenic
groups on each side of the C60 moiety. Interpenetration from
adjacent layers contributes to a good space filling and to the
Compound 4 (second generation dendrimer, n~2). The
˚
measured layer spacing is 65 A. This result is probably due
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Scheme 7 Reagents and conditions: i, DPTS, DCC, 4-PPy, CH2Cl2, 0 uC and then room temperature, 65%; ii, Zn(BF4)2, H2O, THF, room
temperature, 85%; iii, DPTS, DCC, 4-PPy, CH2Cl2, 0 uC and then room temperature, 70%; iv, C60, I2, DBU, toluene, room temperature, 21%. For
R, see Fig. 1.
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Scheme 8 Reagents and conditions: i, Et3N, CH2Cl2, room temperature, 41%; ii, DPTS, DCC, 4-PPy, CH2Cl2, 0 uC and then room temperature, 97%;
iii, C60, I2, DBU, toluene, room temperature, 60%.
Scheme 9 Reagents and conditions: i, DPTS, DCC, 4-PPy, CH2Cl2, 0 uC and then room temperature, 100%; ii, C60, I2, DBU, toluene, room
temperature, 54%.
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Fig. 5 Differential scanning calorimetry thermogram of 4 registered
during the second heating run.
Fig. 4 Visible spectrum of dendrimer 6.
Table 1 Phase transition temperatures of investigated compounds
DH/kJ mol21
per mesogenic
Compound Tga/uC Transitionb T/uC DH/kJ mol21 unit
9
CrAN
NAI
122c 42
224c
0.9
0.9
15
CrASA
SAAN
NAI
129
225d
236
202
95
Fig. 6 Variation of the smectic A layer spacing as a function of the
generation number; n~0: compound 2, n~1: compound 3, n~2:
compound 4; n~3: compound: 5; n~4: compound 6.
1.9
13
0.95
6.5
e
1
SAAI
17
CrASA
SAAN
NAI
97c 83
153c
162c
142
5.5f
13
2.75
6.5
2
29
SAAI
e
21
3
NAI
201c
179
5.4
18
1.4
4.5
48
46
e
SAAI
24
4
SAAN
NAI
SAAN
NAI
196c
202c 21f
183
2.6
2.0
184
16f
e
e
27
5
SAAI
SAAI
232
212
56
57
3.5
3.6
e
e
30
6
SAAI
SAAI
259 198
252c 195
6.2
6.1
e
34
CrASA
SAAN
NAI
71c 51
138d
176c
155
2.8
11
1.4
5.5
e
7
SAAI
Fig. 7 X-Ray diffractogram pattern of 2 in the smectic A phase
recorded at 140 uC.
35
8
34
50
SAA I
SAA I
182
161
11
12
2.75
3.0
aTg~glass transition temperature. bSA~smectic
A
phase,
signals characteristic of a smectic A phase, one should mention
the presence of a diffuse band corresponding to a spacing of 22
˚
and 29 A for 5 and 6, respectively. It is also important to
N~nematic phase, I~isotropic liquid. cFirst heating run. dObserved
by polarized optical microscopy. Not detected. Overall enthalpy.
e
f
remark that the intensity of the Bragg reflections decreases as
the generation number increases, and that these reflections are
not as sharp as for the low generation dendrimers.
stabilization of the smectic A structure through an efficient
lateral arrangement of the mesogenic groups. It is interesting
to note the presence of a diffuse band in the X-ray pattern
To describe the molecular organization, it is necessary to
realize that dendrimers 5 and 6 are mainly constituted of the
branching nodes and of the 16 and 32 mesogenic moieties
including the aliphatic spacers; the fullerene moiety represents
a minor part. It is reasonable to admit that the structure is
governed essentially by the polar cyano groups. The latter tend
to form an anisotropic micro-domain and tend to be oriented
parallel to one another. However, due to the fact that these
groups are attached to one of their extremities and due also to
the fact that the branching nodes are rather voluminous, their
parallel orientation is far from being optimized. As is shown in
˚
corresponding to a distance of 18 A, which was assigned to the
average lateral distance between fullerene moieties, in agree-
ment with the organization proposed.
Compounds 5 (third generation dendrimer, n~3) and 6 (fourth
generation dendrimer, n~4). For both compounds, the layer
spacing in the smectic A phase is very similar and ranges
˚
between 56–57 A. This value is rather small compared to the
size of the dendrimers. In addition to the X-ray diffraction
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Fig. 8 Molecular simulation of the head-to-tail arrangement of 2
within the smectic A phase.
Fig. 12 Molecular simulation of half part of 5 showing the lateral
extension of the branching part of the dendrimer and the cyanobiphe-
nyl groups pointing to one main direction.
Fig. 9 Molecular simulation of 3 with the two arms pointing in the
same direction and bearing a pair of cyanobiphenyl groups.
Fig. 10 Molecular simulation of the supramolecular organization of 3
within the smectic A layers.
Fig. 13 Schematic representation of the supramolecular organization
of 5 within the smectic A layers.
a molecular simulation for one half of the dendrimer 5
containing 8 mesogenic groups (Fig. 12), free space is available
between the terminal cyano groups. Such a conformation
favors interpenetration of mesogenic groups from adjacent
layers. Thus, the molecular organization can be schematized
as illustrated in Fig. 13 for dendrimer 5 (the molecular
organization of 6 is the same; the only difference is the
number of mesogenic groups). The central part of the layer is
constituted by the fullerene moiety embedded by the important
branching part (i.e. the dendrimer), and the layer interface is
formed by the mesogenic cyano groups oriented in one main
direction and partially interdigitated from one layer to the
adjacent one. This interdigitation is in agreement with the
decrease in intensity of the Bragg signals and with their
simultaneous broadening; this is similar to X-ray investigations
of the smectic A to nematic transition where the interface
between the layers becomes more and more diffuse as the
transition temperature is approached.30 Let us remark that
such an organization and the good space filling are presumably
Fig. 11 Schematic representation of the supramolecular organization
of 4 within the smectic A layers.
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made possible thanks to the presence of rather long aliphatic
spacers and to a large number of ester groups which ensure
the necessary flexibility of the dendrimer. Finally, in such a
structure, the diffuse X-ray signals corresponding to spacings
generation dendrimers indicates that the branching part
expands laterally with respect to the plane of the layers.
Comparison of the liquid-crystalline properties of the
malonate derivatives with those of their fullerene counterparts
strengthens the proposed models. On one hand, malonates 15
and 17 exhibit both smectic A and nematic phases, whereas
their corresponding fullerene analogues 1 and 2 display only
smectic A phases. This behavior confirms that for the low
generation dendrimers containing the fullerene unit, the
molecular organization is driven by steric constraints, produ-
cing only smectic A phases: a suitable adequacy between the
cross-sectional areas of the fullerene moiety and that of the
mesogenic groups has to be found. On the other hand,
malonates 24, 27 and 30 and their corresponding fullerene
analogues 4, 5 and 6 exhibit the same mesomorphic behavior,
confirming the preponderant role of the cyano mesogenic
groups.
˚
of 22 and 29 A for 5 and 6, respectively, may be attributed to
the mean average distance between fullerene moieties within
the smectic layers, this distance increasing as expected with the
size of the dendrimer. This indicates that the expansion of the
dendritic volume takes place essentially in two dimensions, as
the dendrimer generation increases.
Malonates 27 and 30 exhibit also smectic A phases with a
˚
layer spacing value of 52 A in both cases. This value is similar
to that found for 5 and 6 and confirms that the fullerene moiety
does not play a significant role in the supramolecular
organization, which is governed by the large number of
mesogenic groups.
A variety of fullerene derivatives with liquid-crystalline
properties can be synthesized by applying the covalent (this
work and references 15–19 and 21) or non-covalent31
approach. The results obtained so far indicate that the
design of fullerene-containing liquid crystals with tailor-made
mesomorphic properties should be feasible.
Compounds 7 and 8. The layer spacings measured are 58 and
˚
78 A for 7 and 8, respectively. Considering that the cross-
sectional area of the fullerene moiety is about four times that of
the mesogenic unit, the supramolecular organization of 7
within the smectic layers is straightforward and is similar to
that represented in Fig. 8. It corresponds to the head-to-tail
arrangement of individual molecules with a good agreement
between the molecular dimensions and the observed layer
spacing. It is interesting to compare 7 with 2, which contains
the same number of mesogenic groups but for which the layer
Experimental
Materials
˚
spacing is much larger (d~76 A for 2). The difference results in
For the syntheses, CH2Cl2 (P2O5, under N2) and toluene (NaH,
under N2) were distilled prior to use. Triethylamine (Fluka,
puriss p.a.) and the other solvents were used as received.
Zn(BF4)2 (hydrated with 6 to 7 molecules of water) was
purchased from Aldrich; we used a molecular weight of 356.09.
[60]Fullerene (99.5%) was purchased from Southern Chemical
Group (Georgia, USA). Compounds 16,17 18,23 and 3225 were
prepared following literature procedures.
the fact that the two mesogenic groups are carried by one arm
in 7, whereas they are attached to two arms in 2. This explains
why the interdigitation is complete in 7 and incomplete in 2,
resulting in a significant difference in the layer spacing. As for
˚
8, for which the layer spacing is 78 A, it is necessary to take into
account the molecular design of this hemi-dendrimer. Similarly
to 3, which contains the same number of mesogenic groups, the
molecular simulation suggests a V-shaped structure, in which
space is available between pairs of mesogenic terminal groups,
so that interdigitation between adjacent layers occurs. In such a
Techniques
˚
description, the layer spacing of 78 A fits the molecular
Column chromatography used silica gel 60 (0.060–0.200 mm,
SDS). Transition temperatures [onset point, second heating run
(except indicated otherwise)] and enthalpies were determined
with a differential scanning Mettler DSC 30 calorimeter
connected to a Mettler TA 4000 processor, under N2, at a
rate of 10 uC min21; Mettler TA72.2/.5 Graphware was used
for data treatment. For 4, 24 and 34, the transition temp-
eratures and enthalpies were determined with a Mettler Toledo
dimensions of the model. Moreover, a good agreement exists
between the cross-sections of four mesogenic groups and of the
fullerene moiety. Thus, the molecular organization of 8 within
the smectic A layers is identical to that described for 3.
The malonates 15, 17, 21 and 24 display a nematic phase, in
contrast to their fullerene derivatives (with the exception of 4
which also shows a nematic phase). This behavior indicates
that i) the fullerene unit tends to prevent the occurence of
nematic order, presumably because of its isotropic and large
shape, and ii) the lateral extension of the branching part is so
pronounced that no longitudinal sliding of the mesogenic
groups in one main direction can take place.
DSC 822e calorimeter, under He, at a rate of 10 uC min21
;
Mettler STARe Software was used for data treatment. The
melting (Tm) and clearing (Tc) points of the intermediates were
determined during the first heating–cooling cycle; for the
dendritic compounds, the glass transition temperatures (Tg)
were not detected. Optical studies were made using a Zeiss-
Axioscop polarizing microscope equipped with a Linkam-
1
THMS-600 variable temperature stage, under N2. H and 13C
Conclusion
NMR spectra were recorded on a Varian Gemini 200
spectrometer or a Bruker 400 spectrometer with the solvent
as internal reference. UV–VIS spectra were recorded on a
Kontron Uvikon Spectrophotometer 930. Modelling studies
were performed using Biosym software running on a Silicon
Graphics Indigo 2 system. For X-ray diffraction analyses, see
ref. 32 Elemental analyses were done by Mikroelementar-
analytisches Laboratorium ETH-Zurich.
The design and study of a family of fullerene-containing liquid-
crystalline dendrimers allowed us to propose models for the
organization of the fullerene-based molecular units within the
liquid-crystalline phases.
For the low generation dendrimers (1 and 2), the organiza-
tion is determined by steric factors: the supramolecular
organization depends on the cross-sectional areas of the
fullerene moiety and that of the mesogenic groups (to fill
the space in an optimized way). For the high generation
dendrimers (3, 4 and 5), the mesogenic groups impose a
microphase organization. Due to the lateral extension of the
branching part, the cyano mesogenic groups are arranged in a
parallel fashion as in classical smectic A phases. The almost
constant value of the layer spacing found for the high
Abbreviations
Column chromatography~CC; 4-(dimethylamino)pyridine~
DMAP; N,N’-dicyclohexylcarbodiimide~DCC; 1,8-diazabi-
cyclo[5.4.0]undec-7-ene~DBU; 4-(dimethylamino)pyridinium
toluene-p-sulfonate~DPTS; 4-pyrrolidinopyridine~4-PPy.
2826
J. Mater. Chem., 2001, 11, 2814–2831

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Syntheses
4.51 (t, 4 H, CO2CH2), 4.04 (t, 4 H, CH2O), 1.9–1.8 (m, 8 H,
CO2CH2CH2 and CH2CH2O), 1.5–1.3 (24 aliph. H). 13C NMR
(50 MHz, CDCl3): 164.81, 163.69, 163.66, 151.55, 145.34,
145.24, 145.15, 144.84, 144.66, 144.58, 143.84, 143.07, 143.01,
142.94, 142.16, 141.88, 140.93, 138.95, 136.69, 132.64, 132.35,
128.33, 127.68, 122.55, 121.22, 118.86, 114.34, 110.97, 71.64,
68.31, 67.41, 52.45, 29.52, 29.49, 29.37, 29.20, 29.10, 28.58,
25.99. Anal. Calcd for C123H64N2O10 (1729.87): C, 85.40; H,
3.73; N, 1.62%. Found: C, 85.49; H, 3.98; N, 1.64%.
Compound 12. To a mixture of 4-hydroxybenzoic acid (11)
(11.51 g, 83.33 mmol), EtOH (200 ml) and a 4 M NaOH
aqueous solution (42 ml) heated under reflux, a solution of
10-bromodecanol (10) (15.10 g, 63.66 mmol) in EtOH (50 ml)
was added dropwise. The mixture was stirred under reflux for
22 h, cooled to room temperature, acidified with a 3 M HCl
aqueous solution (60 ml), and poured into ice. Purification of
the precipitate by crystallization (isopropanol) gave pure 12
1
(12.35 g, 66%). Tm~119 uC. H NMR (200 MHz, CDCl3 and
Compound 17. To a solution of 16 (167 mg, 0.307 mmol)
in CH2Cl2 (50 ml) cooled to 0 uC were added a solution of
DPTS (180 mg, 0.611 mmol), DCC (171 mg, 0.829 mmol) and
4-PPy (spatula tip) in CH2Cl2 (20 ml), and then a solution
of 9 (290 mg, 0.615 mmol) in CH2Cl2 (80 ml). The mixture
was stirred at room temperature for 18 h, and evaporated to
dryness. Purification of the solid residue by CC (CH2Cl2–
AcOEt 10 : 0.5) gave pure 17 (229 mg, 51%). 1H NMR
(200 MHz, CDCl3): d 8.16, (d, 4 arom. H), 7.98 (d, 4 arom.
H), 7.74 (d, 4 arom. H), 7.68 (d, 4 arom. H), 7.64 (d, 4 arom.
H), 7.33 (d, 4 arom. H), 6.99 (d, 4 arom. H), 6.89 (d, 4 arom.
H), 4.28 (t, 4 H, ben-CO2CH2), 4.16 (t, 4 H, mal-CO2CH2), 4.05
(t, 4 H, (CH2)9CH2O), 3.99 (t, 4 H, (CH2)5CH2O), 3.37 (s, 2 H,
O2CCH2CO2), 1.9–1.6 (m, 16 H, CO2CH2CH2 and
CH2CH2O), 1.6–1.2 (m, 32 aliph. H). 13C NMR (50 MHz,
CDCl3): d 166.63, 166.43, 164.81, 163.66, 162.73, 151.55,
144.83, 136.66, 132.61, 132.32, 131.49, 128.30, 127.65, 122.73,
122.54, 121.16, 118.85, 114.33, 113.95, 110.94, 68.31, 67.87,
65.41, 64.74, 41.57, 29.40, 29.28, 29.22, 29.04, 28.95, 28.73,
28.34, 25.99, 25.93, 25.59, 25.53. Anal. Calcd for C89H98N2O16
(1451.76): C, 73.63; H, 6.80; N, 1.93%. Found: C, 73.74; H,
6.96; N, 1.91%.
a few drops of d6-DMSO): d 7.92 (d, 2 arom. H), 6.82 (d, 2
arom. H), 4.76 (br, 1 H, OH), 3.93 (t, 2 H, CH2O), 3.53 (t, 2 H,
CH2OH), 1.8–1.6 (m, 2 H, CH2CH2O), 1.6–1.2 (14 H,
CH2CH2OH and 12 aliph. H). 13C NMR (50 MHz, CDCl3
and a few drops of d6-DMSO): d 168.37, 162.69, 131.67, 122.70,
113.82, 68.00, 62.61, 32.64, 29.35, 29.30, 29.16, 28.94, 25.80,
25.63.
Compound 9. A mixture of 12 (7.60 g 25.82 mmol),
4-hydroxycyanobiphenyl (13) (5.15 g, 26.38 mmol), DMAP
(3.24 g, 26.52 mmol), DCC (8.8 g, 43 mmol) and CH2Cl2
(300 ml) was stirred at room temperature for 20 h, and
evaporated to dryness. Purification of the solid residue by
CC (CH2Cl2–AcOEt 10 : 1) gave pure 9 (9.82 g, 81%). 1H NMR
(200 MHz, CDCl3): d 8.16 (d, 2 arom. H), 7.75 (d, 2 arom. H),
7.69 (d, 2 arom. H), 7.64 (d, 2 arom. H), 7.33 (d, 2 arom. H),
6.99 (d, 2 arom. H), 4.06 (t, 2 H, CH2O), 3.65 (t, 2 H, CH2OH),
1.9–1.7 (m, 2 H, CH2CH2O), 1.6–1.2 (14 H, CH2CH2OH and
12 aliph. H). 13C NMR (50 MHz, CDCl3): d 164.82, 163.68,
151.55, 144.86, 136.67, 132.63, 132.33, 128.32, 127.67, 122.55,
121.17, 118.87, 114.34, 110.96, 68.32, 62.96, 32.74, 29.49, 29.44,
29.38, 29.31, 29.06, 25.94, 25.72. Anal. Calcd for C30H33NO4
(471.60): C, 76.41; H, 7.05; N, 2.97%. Found: C, 76.37, H, 7.14,
N, 3.01%.
Compound 2. To a solution of C60 (126 mg, 0.175 mmol) in
toluene (125 ml) were added a suspension of 17 (180 mg,
0.124 mmol) in toluene (50 ml), a solution of iodine (32 mg,
0.126 mmol) in toluene (10 ml) and DBU (38 mg, 0.250 mmol).
The mixture was stirred at room temperature for 24 h, and
evaporated to dryness. Purification of the solid residue by CC
(first with toluene to eliminate unreacted C60, and then with
toluene–AcOEt 10 : 0.25) and precipitation (dissolution in
CH2Cl2 and precipitation by pouring the solution into acetone)
Note: the synthesis of 9 can also be carried out in the
presence of DPTS and 4-PPy instead of DMAP (for example,
see the preparation of 17).
Compound 15. To a mixture of 9 (376 mg, 0.797 mmol),
malonyl chloride (14) (56 mg, 0.397 mmol) and CH2Cl2
(25 ml), was added a solution of Et3N (80 mg, 0.791 mmol)
in CH2Cl2 (5 ml). The mixture was stirred at room temperature
for 18 h, and evaporated to dryness. Purification of the solid
residue by CC (CH2Cl2–AcOEt 10 : 0.5) gave pure 15 (368 mg,
92%). 1H NMR (200 MHz, CDCl3): d 8.16 (d, 4 arom. H), 7.75
(d, 4 arom. H), 7.68 (d, 4 arom. H), 7.64 (d, 4 arom. H), 7.32 (d,
4 arom. H), 6.98 (d, 4 arom. H), 4.15 (t, 4 H, CO2CH2), 4.05 (t,
4 H, CH2O), 3.38 (s, 2 H, O2CCH2CO2), 1.9–1.7 (m, 4 H,
gave pure
2 (134 mg, 50%). VIS (lmax in nm (e in
dm3 mol21 cm21), CH2Cl2): 426 (2780), 489 (1620), 687
(210). 1H NMR (400 MHz, CDCl3): d 8.16 (d, 4 arom. H),
7.97 (d, 4 arom. H), 7.74 (d, 4 arom. H), 7.69 (d, 4 arom. H),
7.64 (d, 4 arom. H), 7.33 (d, 4 arom. H), 6.98 (d, 4 arom. H),
6.88 (d, 4 arom. H), 4.51 (t, 4 H, C60CCO2CH2), 4.28 (t, 4 H,
ben-CO2CH2), 4.05 (t, 4 H, (CH2)9CH2O), 4.00 (t, 4 H,
(CH2)5CH2O), 1.9–1.7 (m, 16 H, CO2CH2CH2 and
CH2CH2O), 1.5–1.3 (m, 32 aliph. H). 13C NMR (50 MHz,
CDCl3): d 166.40, 164.81, 163.66, 162.67, 151.55, 145.25,
145.15, 145.05, 144.84, 144.64, 144.57, 143.83, 143.05, 142.98,
142.93, 142.14, 141.82, 140.91, 138.89, 136.66, 132.63, 132.32,
131.52, 128.32, 127.67, 122.79, 122.54, 121.17, 118.86, 114.34,
113.96, 110.94, 71.57, 68.31, 67.81, 67.23, 64.76, 52.34, 29.43,
29.29, 29.23, 29.04, 28.75, 28.51, 25.99, 25.94, 25.65. Anal.
Calcd for C149H96N2O16 (2170.40): C, 82.46; H, 4.46; N, 1.29.
Found: C, 82.54; H, 4.61; N, 1.20%.
CH2CH2O), 1.7–1.2 (28 H, CO2CH2CH2 and 24 aliph. H). 13
C
NMR (50 MHz, CDCl3): d 166.68, 164.78, 163.64, 151.52,
144.80, 136.65, 132.60, 132.31, 128.29, 127.63, 122.51, 121.16,
118.83, 114.30, 110.93, 68.28, 65.59, 41.65, 29.40, 29.28, 29.13,
29.04, 28.40, 25.93, 25.73. Anal. Calcd for C63H66N2O10
(1011.22): C, 74.83; H, 6.58; N, 2.77%. Found: C, 74.95; H,
6.73; N, 2.75%.
Compound 1. To a solution of C60 (241 mg, 0.334 mmol) in
toluene (250 ml) were added a suspension of 15 (240 mg,
0.237 mmol) in toluene (20 ml), a solution of iodine (60 mg,
0.236 mmol) in toluene (20 ml) and DBU (72 mg, 0.473 mmol).
The mixture was stirred at room temperature for 15 h, and
evaporated to dryness. Purification of the solid residue by CC
(first with toluene to eliminate unreacted C60, and then with
toluene–AcOEt 10 : 0.25) and precipitation (dissolution in
CH2Cl2 followed by addition of AcOEt) gave pure 1 (90 mg,
22%). VIS (lmax in nm (e in dm3 mol21 cm21), CH2Cl2): 426
Compound 19. To a suspension of 18 (1.57 g, 5.30 mmol) in
CH2Cl2 (50 ml) cooled to 0 uC, were added a solution of DPTS
(0.55 g, 1.87 mmol), DCC (5.45 g, 26.4 mmol) and 4-PPy
(spatula tip) in CH2Cl2 (40 ml), and then a solution of 9
(5.01 g, 10.6 mmol) in CH2Cl2 (100 ml). The mixture was
stirred at room temperature for 18 h, and evaporated to
dryness. Purification of the solid residue by CC (CH2Cl2–
AcOEt 10 : 0.5) gave pure 19 (6.08 g, 95%). Tm~96 uC,
1
(2680), 486 (1610), 688 (210). H NMR (400 MHz, CDCl3): d
8.15 (d, 4 arom. H), 7.74 (d, 4 arom. H), 7.69 (d, 4 arom. H),
7.64 (d, 4 arom. H), 7.33 (d, 4 arom. H), 6.97 (d, 4 arom. H),
1
Tc~193 uC. H NMR (400 MHz, CDCl3): d 8.29 (t, 1 arom.
H), 8.16 (d, 4 arom. H), 7.74 (d, 4 arom. H), 7.69 (d, 4 arom.
J. Mater. Chem., 2001, 11, 2814–2831
2827

View Article Online
H), 7.68 (d, 2 arom. H), 7.64 (d, 4 arom. H), 7.33 (d, 4 arom.
H), 6.98 (d, 4 arom. H), 4.33 (t, 4 H, CO2CH2), 4.05 (t, 4 H,
CH2O), 1.8–1.7 (m, 8 H, CO2CH2CH2 and CH2CH2O), 1.6–1.3
(m, 24 aliph. H); 1.00 (s, 9 H, (CH3)3CSi), 0.24 (s, 6 H,
(CH3)2Si). 13C NMR (100 MHz, CDCl3): d 165.69, 164.79,
163.64, 155.81, 151.53, 144.81, 136.65, 132.61, 132.31, 132.11,
128.31, 127.64, 125.15, 123.48, 122.53, 121.15, 118.85, 114.31,
110.94, 68.29, 65.42, 29.43, 29.31, 29.20, 29.06, 28.61, 25.94,
25.58, 18.18, 24.47. Anal. Calcd for C74H82N2O11Si (1203.55):
C, 73.85; H, 6.87; N, 2.33%. Found: C, 73.89; H, 6.90; N,
2.22%.
144.55, 144.52, 143.79, 143.05, 142.98, 142.90, 142.11, 141.79,
140.91, 138.88, 136.62, 132.60, 132.43, 132.29, 128.29, 127.88,
127.63, 127.27, 122.52, 121.14, 120.85, 118.83, 114.31, 110.93,
71.55, 68.29, 68.00, 67.21, 65.71, 52.36, 29.37, 29.28, 29.19,
29.02, 28.60, 25.90, 25.62. Anal. Calcd for C225H166N4O30
(3405.80): C, 79.35; H, 4.91; N, 1.65%. Found: C, 79.14; H,
5.06; N, 1.62%.
Compound 22. To a suspension of 18 (544 mg, 1.84 mmol)
in CH2Cl2 (50 ml) cooled to 0 uC, were added a solution of
DPTS (907 mg, 3.08 mmol), DCC (1.71 g, 8.29 mmol) and
4-PPy (spatula tip) in CH2Cl2 (20 ml), and then a solution of
20 (4.01 g, 3.68 mmol) in CH2Cl2 (100 ml). The mixture was
stirred at room temperature for 18 h, and evaporated to
dryness. Purification of the solid residue by CC (CH2Cl2–
AcOEt 10 : 0.5) and precipitation (dissolution in CH2Cl2 and
precipitation by pouring the solution into MeOH) gave pure 22
(4.25 g, 95%). Tc~214 uC. 1H NMR (200 MHz, CDCl3): d 8.63
(t, 1 arom. H), 8.61 (t, 2 arom. H), 8.12 (d, 8 arom. H), 8.09 (d,
4 arom. H), 7.91 (d, 2 arom. H), 7.71 (d, 8 arom. H), 7.65 (d, 8
arom. H), 7.61 (d, 8 arom. H), 7.30 (d, 8 arom. H), 6.95
(d, 8 arom. H), 4.35 (t, 8 H, CO2CH2), 4.02 (t, 8 H, CH2O),
1.9–1.6 (m, 16 H, CO2CH2CH2 and CH2CH2O), 1.6–1.3 (m, 48
aliph. H), 1.02 (s, 9 H, (CH3)3CSi), 0.29 (s, 6 H, (CH3)2Si).
Anal. Calcd for C150H152N4O25Si (2438.95): C, 73.87; C, 6.28;
N, 2.30%. Found: C, 73.86; H, 6.37; N, 2.33%.
Compound 20. To a solution of 19 (5.85 g, 4.86 mmol) in
THF (200 ml), were added Zn(BF4)2 (4.2 g, 11.8 mmol) and
H2O (10 ml). The mixture was stirred at room temperature for
18 h, and THF was evaporated. Addition of water (100 ml) led
to the formation of a precipitate which was removed by
filtration. Trituration of the solid residue with hot AcOEt gave
pure 20 (4.80 g, 91%). Tm~149 uC, Tc~243 uC. 1H NMR
(200 MHz, CDCl3): d 8.26 (t, 1 arom. H), 8.16 (d, 4 arom. H),
7.75 (d, 4 arom. H), 7.69 (d, 2 arom. H), 7.68 (d, 4 arom. H),
7.64 (d, 4 arom. H), 7.32 (d, 4 arom. H), 6.98 (d, 4 arom. H),
5.51 (s, 1 H, OH), 4.33 (t, 4 H, CO2CH2), 4.05 (t, 4 H, CH2O),
1.9–1.7 (m, 8 H, CO2CH2CH2 and CH2CH2O), 1.6–1.3 (m, 24
aliph. H). Anal. Calcd for C68H68N2O11 (1089.29): C, 74.98; H,
6.29; N, 2.57%. Found: C, 74.92; H, 6.27; N, 2.60%.
Compound 21. To a solution of 16 (185 mg, 0.340 mmol) in
CH2Cl2 (50 ml) cooled to 0 uC, were added a solution of DPTS
(200 mg, 0.679 mmol), DCC (154 mg, 0.746 mmol) and 4-PPy
(spatula tip) in CH2Cl2 (20 ml), and then a solution of 20
(740 mg, 0.679 mmol) in CH2Cl2 (100 ml). The mixture was
stirred at room temperature for 18 h, and evaporated to
dryness. Purification of the solid residue by CC (CH2Cl2–
AcOEt 10 : 0.25) gave pure 21 (488 mg, 53%). 1H NMR
(400 MHz, CDCl3): d 8.60 (t, 2 arom. H), 8.15 (d, 12 arom. H),
8.06 (d, 4 arom. H), 7.73 (d, 8 arom. H), 7.68 (d, 8 arom. H),
7.63 (d, 8 arom. H), 7.32 (d, 8 arom. H), 6.98 (d, 12 arom. H),
4.35 (t, 8 H, isoph-CO2CH2), 4.17 (t, 4 H, mal-CO2CH2), 4.05
(t, 4 H, (CH2)5CH2O), 4.04 (t, 8 H, (CH2)9CH2O), 3.39 (s, 2 H,
O2CCH2CO2), 1.9–1.6 (m, 24 H, CO2CH2CH2 and
CH2CH2O), 1.6–1.3 (m, 56 aliph. H). 13C NMR (100 MHz,
CDCl3): d 166.64, 165.03, 164.78, 164.47, 163.70, 163.64,
151.52, 151.01, 144.79, 136.62, 132.59, 132.39, 132.29, 128.28,
127.86, 127.63, 127.26, 122.51, 121.13, 120.79, 118.83, 114.35,
114.30, 110.92, 68.28, 68.06, 65.70, 65.38, 41.55, 29.40, 29.36,
29.26, 29.17, 29.02, 28.91, 28.59, 28.34, 25.90, 25.88, 25.59,
25.52. Anal. Calcd for C165H168N4O30 (2687.15): C, 73.75; H,
6.30; N, 2.08%. Found: C, 73.59; H, 6.28; N, 2.10%.
Compound 23. To a solution of 22 (3.60 g, 1.48 mmol) in
THF (200 ml), were added Zn(BF4)2 (3.0 g, 8.4 mmol) and H2O
(10 ml). The mixture was stirred at room temperature for 18 h.
Evaporation of THF gave a precipitate which was removed by
filtration. Purification of the solid residue by CC (CH2Cl2–
AcOEt 10 : 0.25 and then 10 : 0.5) gave pure 23 (3.10 g, 90%).
1
Tc~230 uC. H NMR (200 MHz, CDCl3): d 8.63 (t, 2 arom.
H), 8.58 (t, 1 arom. H), 8.15 (d, 8 arom. H), 8.09 (d, 4 arom. H),
7.94 (d, 2 arom. H), 7.74 (d, 8 arom. H), 7.68 (d, 8 arom. H),
7.63 (d, 8 arom. H), 7.32 (d, 8 arom. H), 6.97 (d, 8 arom. H),
6.40 (br, 1 H, OH), 4.36 (t, 8 H, CO2CH2), 4.04 (t, 8 H, CH2O),
1.9–1.7 (m, 16 H, CO2CH2CH2 and CH2CH2O), 1.6–1.3 (m, 48
aliph. H). Anal. Calcd for C144H138N4O25 (2324.69): C, 74.40;
H, 5.98; N, 2.41%. Found: C, 74.33; H, 6.05; N, 2.41%.
Compound 24. To a solution of 16 (118 mg, 0.217 mmol) in
CH2Cl2 (5 ml) cooled to 0 uC, were added a solution of DPTS
(127 mg, 0.431 mmol), DCC (424 mg, 2.05 mmol) and 4-PPy
(spatula tip) in CH2Cl2 (5 ml), and then a solution of 23 (1.01 g,
0.434 mmol) in CH2Cl2 (20 ml). The mixture was stirred at
room temperature for 18 h, and evaporated to dryness.
Purification of the solid residue by CC (CH2Cl2–AcOEt
10 : 0.3 then 10 : 0.5) gave pure 24 (0.71 g, 63%). 1H NMR
(200 MHz, CDCl3): d 8.93 (t, 2 arom. H), 8.63 (t, 4 arom. H),
8.35 (d, 4 arom. H), 8.17 (d, 4 arom. H), 8.14 (d, 16 arom. H),
8.10 (d, 8 arom. H), 7.74 (d, 16 arom. H), 7.67 (d, 16 arom. H),
7.63 (d, 16 arom. H), 7.31 (d, 16 arom. H), 6.99 (d, 4 arom. H),
6.97 (d, 16 arom. H), 4.36 (t, 16 H, isoph-CO2CH2), 4.17 (t, 4
H, mal-CO2CH2), 4.03 (t, 20 H, CH2O), 3.38 (s, 2 H,
O2CCH2CO2), 1.9–1.6 (m, 40 H, CO2CH2CH2 and CH2CH2O),
1.6–1.3 (m, 104 aliph. H). Anal. Calcd for C317H308N8O58
(5157.94): C, 73.82; H, 6.02; N, 2.17%. Found: C, 73.64; H,
6.15; N, 2.28%.
Compound 3. To a solution of C60 (147 mg, 0.204 mmol) in
toluene (150 ml), were added a suspension of 21 (450 mg,
0.167 mmol) in toluene (50 ml), a solution of iodine (44 mg,
0.173 mmol) in toluene (15 ml) and DBU (51 mg, 0.335 mmol).
The mixture was stirred at room temperature for 15 h, and
evaporated to dryness. Purification of the solid residue by CC
(first with toluene to eliminate unreacted C60, and then with
toluene–AcOEt 10 : 0.25) and precipitation (dissolution in
toluene and precipitation by pouring the solution into acetone)
gave pure
3 (164 mg, 29%). VIS (lmax in nm (e in
dm3 mol21 cm21), CH2Cl2): 426 (2780), 488 (1640), 687
(210). 1H NMR (200 MHz, CDCl3): d 8.59 (t, 2 arom. H),
8.15 (d, 8 arom. H), 8.13 (d, 4 arom. H), 8.05 (d, 4 arom. H),
7.74 (d, 8 arom. H), 7.68 (d, 8 arom. H), 7.63 (d, 8 arom. H),
7.32 (d, 8 arom. H), 6.98 (d, 12 arom. H), 4.53 (t, 4 H,
C60CCO2CH2), 4.35 (t, 8 H, isoph-CO2CH2), 4.05 (t, 4 H,
(CH2)5CH2O), 4.04 (t, 8 H, (CH2)9CH2O), 2.0–1.6 (m, 24 H,
CO2CH2CH2 and CH2CH2O), 1.6–1.2 (m, 56 aliph. H). 13C
NMR (50 MHz, CDCl3): d 165.02, 164.76, 164.43, 163.64,
151.53, 151.00, 145.24, 145.21, 145.13, 145.02, 144.80, 144.61,
Compound 4. To a solution of C60 (210 mg, 0.291 mmol)
in toluene (250 ml), were added a solution of 24 (581 mg,
0.113 mmol) in toluene (5 ml), a solution of iodine (28 mg,
0.113 mmol) in toluene (5 ml) and DBU (34 mg, 0.223 mmol).
The mixture was stirred at room temperature for 18 h, and
evaporated to dryness. Purification of the solid residue by CC
(first with toluene to eliminate unreacted C60, and then with
toluene–CH2Cl2–AcOEt 10 : 5 : 0.5) and precipitation (dissolu-
tion in CH2Cl2 and precipitation by pouring the solution into
2828
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MeOH) gave pure 4 (287 mg, 43%). VIS (lmax in nm (e in
dm3 mol21 cm21), CH2Cl2): 426 (2910), 489 (1700), 687 (200).
1H NMR (200 MHz, CDCl3): 8.93 (t, 2 arom. H), 8.63 (t, 4
arom. H), 8.34 (t, 4 arom. H), 8.14 (d, 20 arom. H), 8.11 (d, 8
arom. H), 7.74 (d, 16 arom. H), 7.67 (d, 16 arom. H), 7.63 (d, 16
arom. H), 7.31 (d, 16 arom. H), 6.97 (d, 20 arom. H), 4.53
(t, 4 H, C60CCO2CH2), 4.36 (t, 16 H, isoph-CO2CH2), 4.03
(t, 20 H, CH2O), 1.9–1.7 (m, 40 H, CO2CH2CH2 and
CH2CH2O), 1.6–1.3 (m, 104 aliph. H). Anal. Calcd for
(first with toluene to eliminate unreacted C60, and then with
CH2Cl2–AcOEt 10 : 0.5) and precipitation (dissolution in
CH2Cl2 and precipitation by pouring the solution into acetone)
gave pure
5 (115 mg, 24%). VIS (lmax in nm (e in
dm3 mol21 cm21), CH2Cl2): 426 (4390), 462 (2900), 688
(210). 1H NMR (200 MHz, CDCl3): d 8.98 (t, 6 arom. H),
8.62 (t, 8 arom. H), 8.40 (d, 8 arom. H), 8.39 (d, 4 arom. H),
8.13 (d, 36 arom. H), 8.11 (d, 16 arom. H), 7.72 (d, 32 arom. H),
7.66 (d, 32 arom. H), 7.61 (d, 32 arom. H), 7.30 (d, 32 arom. H),
6.95 (d, 36 arom. H), 4.52 (t, 4 H, C60CCO2CH2), 4.35 (t, 32 H,
isoph-CO2CH2), 4.02 (t, 36 H, CH2O), 1.9–1.6 (m, 72 H,
CO2CH2CH2 and CH2CH2O), 1.3–1.6 (m, 200 aliph. H). Anal.
Calcd for C681H586N16O114 (10818.16): C, 75.61; H, 5.46; N,
2.07%. Found: C, 75.69; H, 5.62; N, 2.08%.
C377H306N8O58 (5876.58): C, 77.05; H, 5.25; N, 1.91%.
Found: C, 77.02; H, 5.49; N, 1.93%.
Compound 25. To a suspension of 18 (164 mg, 0.553 mmol)
in CH2Cl2 (10 ml) cooled to 0 uC, were added a solution of
DPTS (200 mg, 0.679 mmol), DCC (450 mg, 2.18 mmol) and
4-PPy (spatula tip) in CH2Cl2 (10 ml), and then a solution of 23
(2.51 g, 1.08 mmol) in CH2Cl2 (20 ml). The mixture was stirred
at room temperature for 18 h, and evaporated to dryness.
Purification of the solid residue by CC (CH2Cl2–AcOEt
10 : 0.5) gave pure 25 (2.65 g, 100%). Tc~233 uC. 1H NMR
(200 MHz, CDCl3): d 8.97 (t, 2 arom. H), 8.68 (t, 1 arom. H),
8.63 (t, 4 arom. H), 8.39 (d, 4 arom. H), 8.13 (d, 16 arom. H),
8.11 (d, 8 arom. H), 7.96 (d, 2 arom. H), 7.73 (d, 16 arom. H),
7.67 (d, 16 arom. H), 7.62 (d, 16 arom. H), 7.31 (d, 16 arom. H),
6.96 (d, 16 arom. H), 4.36 (t, 16 H, CO2CH2), 4.03 (t, 16 H,
CH2O), 1.9–1.7 (m, 32 H, CO2CH2CH2 and CH2CH2O), 1.6–
1.3 (m, 96 aliph. H), 1.04 (s, 9 H, (CH3)3CSi), 0.31 (s, 6 H,
(CH3)2Si). Anal. Calcd for C302H292N8O53Si (4909.74): C,
73.88; H, 5.99; N, 2.28%. Found: C, 73.66; H, 6.19; N, 2.35%.
Compound 28. To a suspension of 18 (62 mg, 0.209 mmol) in
CH2Cl2 (5 ml) cooled to 0 uC were added a solution of DPTS
(75 mg, 0.255 mmol), DCC (186 mg, 0.901 mmol) and 4-PPy
(spatula tip) in CH2Cl2 (5 ml), and then a solution of 26 (2.02 g,
0.421 mmol) in CH2Cl2 (20 ml). The mixture was stirred at
room temperature for 18 h, and evaporated to dryness.
Purification of the solid residue by CC (CH2Cl2–AcOEt
10 : 1) gave pure 28 (1.34 g, 65%). Tc~254 uC. 1H NMR
(200 MHz, CDCl3): d 9.00 (t, 2 arom. H), 8.97 (t, 4 arom. H),
8.67 (t, 1 arom. H), 8.61 (t, 8 arom. H), 8.42 (d, 4 arom. H), 8.39
(d, 8 arom. H), 8.12 (d, 32 arom. H), 8.10 (d, 16 arom. H), 7.97
(d, 2 arom. H), 7.72 (d, 32 arom. H), 7.65 (d, 32 arom. H), 7.61
(d, 32 arom. H), 7.29 (d, 32 arom. H), 6.95 (d, 32 arom. H), 4.34
(t, 32 H, CO2CH2), 4.01 (t, 32 H, CH2O), 1.9–1.6 (m, 64 H,
CO2CH2CH2 and CH2CH2O), 1.6–1.3 (m, 192 aliph. H), 1.02
(s, 9 H, (CH3)3CSi), 0.30 (s, 6 H, (CH3)2Si). Anal. Calcd for
Compound 26. To a solution of 25 (2.65 g, 0.540 mmol) in
THF (100 ml), were added Zn(BF4)2 (2.1 g, 5.9 mmol) and H2O
(5 ml). The mixture was stirred at room temperature for 18 h.
Evaporation of THF gave a precipitate which was removed by
filtration. Purification of the solid residue by CC (CH2Cl2–
AcOEt 10 : 0.25) gave pure 26 (2.46 g, 95%). Tc~247 uC. 1H
NMR (200 MHz, CDCl3): d 8.97 (t, 2 arom. H), 8.63 (t, 4 arom.
H), 8.59 (t, 1 arom. H), 8.36 (d, 4 arom. H), 8.14 (d, 16 arom.
H), 8.11 (d, 8 arom. H), 7.95 (d, 2 arom. H), 7.73 (d, 16 arom.
H), 7.66 (d, 16 arom. H), 7.62 (d, 16 arom. H), 7.31 (d, 16 arom.
H), 6.96 (d, 16 arom. H), 4.36 (t, 16 H, CO2CH2), 4.02 (t, 16 H,
CH2O), 1.9–1.7 (m, 32 H, CO2CH2CH2 and CH2CH2O), 1.6–
1.2 (m, 96 aliph. H). Anal. Calcd for C296H278N8O53 (4795.47):
C, 74.14; H, 5.84; N, 2.34%. Found: C, 74.01; H, 5.95; N,
2.32%.
C606H572N16O109Si (9851.31): C, 73.89; H, 5.85; N, 2.27%.
Found: C, 73.85; H, 6.02; N, 2.21%.
Compound 29. To a solution of 28 (1.34 g, 0.136 mmol) in
THF (50 ml) were added Zn(BF4)2 (0.8 g, 2.2 mmol) and H2O
(3 ml). The mixture was stirred at room temperature for 18 h.
Evaporation of THF gave a precipitate which was removed by
filtration. Purification of the solid residue by CC (CH2Cl2–
AcOEt 10 : 0.5) gave pure 29 (1.12 g, 85%). Tc~256 uC. 1H
NMR (200 MHz, CDCl3): d 9.03 (t, 2 arom. H), 9.00 (t, 4 arom.
H), 8.64 (t, 8 arom. H), 8.59 (t, 1 arom. H), 8.43 (d, 8 arom. H),
8.42 (d, 4 arom. H), 8.13 (d, 16 arom. H), 8.12 (d, 32 arom. H),
7.97 (d, 2 arom. H), 7.71 (d, 32 arom. H), 7.65 (d, 32 arom. H),
7.61 (d, 32 arom. H), 7.30 (d, 32 arom. H), 6.96 (d, 32 arom. H),
4.36 (t, 32 H, CO2CH2), 4.02 (t, 32 CH2O), 1.9–1.7 (m, 64 H,
CO2CH2CH2 and CH2CH2O), 1.6–1.2 (m, 192 aliph. H). Anal.
Calcd for C600H558N16O109 (9737.05): C, 74.01; H, 5.78; N,
2.30%. Found: C, 73.92; H, 5.94; N, 2.26%.
Compound 27. To a solution of 16 (57 mg, 0.105 mmol) in
CH2Cl2 (5 ml) cooled to 0 uC, were added a solution of DPTS
(57 mg, 0.194 mmol), DCC (88 mg, 0.427 mmol) and 4-PPy
(spatula tip) in CH2Cl2 (5 ml), and then a solution of 26 (1.00 g,
0.209 mmol) in CH2Cl2 (10 ml). The mixture was stirred at
room temperature for 18 h, and evaporated to dryness.
Purification of the solid residue by CC (CH2Cl2–AcOEt
10 : 0.5 then 10 : 1) gave pure 27 (684 mg, 65%). 1H NMR
(200 MHz, CDCl3): d 8.97 (t, 6 arom. H), 8.63 (t, 8 arom. H),
8.40 (d, 12 arom. H), 8.13 (d, 36 arom. H), 8.11 (d, 16 arom. H),
7.73 (d, 32 arom. H), 7.66 (d, 32 arom. H), 7.62 (d, 32 arom. H),
7.30 (d, 32 arom. H), 6.96 (d, 36 arom. H), 4.35 (t, 32 H, isoph-
CO2CH2), 4.16 (t, 4 H, mal-CO2CH2), 4.02 (t, 36 H, CH2O),
3.38 (s, 2 H, O2CCH2CO2), 1.9–1.7 (m, 72 H, CO2CH2CH2 and
CH2CH2O), 1.6–1.3 (m, 200 aliph. H). Anal. Calcd. for
Note: for the synthesis of 23, 26 and 29, removal of the THF
sometimes gave a gummy compound which was difficult to
recover by filtration. In such cases, CH2Cl2 was added, the
organic layer was separated from water, dried (MgSO4), and
concentrated to dryness. The solid residue was then purified by
CC as described in the procedures.
Compound 30. To a solution of 16 (25 mg, 0.046 mmol) in
CH2Cl2 (5 ml) cooled to 0 uC were added a solution of DPTS
(20 mg, 0.068 mmol), DCC (40 mg, 0.194 mmol) and 4-PPy
(spatula tip) in CH2Cl2 (5 ml), and then a solution of 29
(900 mg, 0.092 mmol) in CH2Cl2 (10 ml). The mixture was
stirred at room temperature for 18 h, and evaporated to
dryness. Purification of the solid residue by CC (CH2Cl2–
C621H588N16O114 (10099.52): C, 73.85; H, 5.87; N, 2.22%.
Found: C, 73.69; H, 5.94; N, 2.25%.
1
AcOEt 10 : 0.5 then 10 : 0.7) gave pure 30 (639 mg, 70%). H
Compound 5. To a solution of C60 (65 mg, 0.090 mmol) in
toluene (100 ml), were added a solution of 27 (451 mg,
0.045 mmol) in CH2Cl2 (5 ml), a solution of iodine (11 mg,
0.043 mmol) in toluene (5 ml) and DBU (14 mg, 0.092 mmol).
The mixture was stirred at room temperature for 18 h, and
evaporated to dryness. Purification of the solid residue by CC
NMR (200 MHz, CDCl3): d 9.02 (t, 4 arom. H), 8.98 (t, 8 arom.
H), 8.96 (t, 2 arom. H), 8.62 (t, 16 arom. H), 8.43 (d, 8 arom.
H), 8.40 (d, 20 arom. H), 8.13 (d, 68 arom. H), 8.12 (d, 32 arom.
H), 7.71 (d, 64 arom. H), 7.65 (d, 64 arom. H), 7.61 (d, 64 arom.
H), 7.29 (d, 64 arom. H), 6.95 (d, 68 arom. H), 4.35 (t, 64 H,
isoph-CO2CH2), 4.15 (t, 4 H, mal-CO2CH2), 4.01 (t, 68 H,
J. Mater. Chem., 2001, 11, 2814–2831
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CH2O), 3.38 (s, 2 H, O2CCH2CO2), 1.9–1.7 (m, 136 H,
CO2CH2CH2 and CH2CH2O), 1.6–1.2 (m, 392 aliph. H). Anal.
Calcd for C1229H1148N32O226 (19982.67): C, 73.87; H, 5.79; N,
2.24%. Found: C, 73.88; H, 5.80; N, 2.26%.
0.209 mmol) in CH2Cl2 (5 ml), a solution of iodine (53 mg,
0.209 mmol) in toluene (5 ml) and DBU (64 mg, 0.420 mmol).
The mixture was stirred at room temperature for 18 h, and
evaporated to dryness. Purification of the solid residue by CC
(first with toluene to eliminate unreacted C60, and then with
CH2Cl2–AcOEt 10 : 0.15) and precipitation (dissolution in
CH2Cl2 and precipitation by pouring the solution into acetone)
Compound 6. To a solution of C60 (52 mg, 0.072 mmol) in
toluene (100 ml), were added a solution of 30 (481 mg,
0.024 mmol) in CH2Cl2 (5 ml), a solution of iodine (6 mg,
0.024 mmol) in toluene (5 ml) and DBU (7 mg, 0.046 mmol).
The mixture was stirred at room temperature for 18 h, and
evaporated to dryness. Purification of the solid residue by CC
(first with toluene to eliminate unreacted C60, and then with
CH2Cl2–AcOEt 10 : 0.6) and precipitation (dissolution in
CH2Cl2 and precipitation by pouring the solution into acetone)
gave pure
7 (269 mg, 60%). VIS (lmax in nm (e in
dm3 mol21 cm21), CH2Cl2): 426 (2680), 486 (1550), 687
(220). 1H NMR (200 MHz, CDCl3): d 8.60 (t, 1 arom. H),
8.15 (d, 4 arom. H), 8.14 (d, 2 arom. H), 8.05 (d, 2 arom. H),
7.75 (d, 4 arom. H), 7.68 (d, 4 arom. H), 7.64 (d, 4 arom. H),
7.33 (d, 4 arom. H), 6.98 (d, 6 arom. H), 4.57 (m, 2 H,
CO2CH2CH3), 4.54 (t, 2 H, C60CCO2CH2), 4.36 (t, 4 H, isoph-
CO2CH2), 4.07 (t, 2 H, CH2O), 4.04 (t, 4 H, CH2O), 2.0–1.7 (m,
12 H, CO2CH2CH2 and CH2CH2O), 1.49 (t, 3 H, CH3), 1.6–1.3
(m, 28 aliph. H). 13C NMR (50 MHz, CDCl3): d 165.02, 164.76,
164.45, 163.63, 163.52, 151.50, 150.99, 145.30, 145.18, 145.10,
144.80, 144.60, 144.54, 143.79, 143.01, 142.94, 142.87, 142.11,
141.82, 141.79, 140.88, 139.04, 138.80, 136.62, 132.60, 132.43,
132.29, 128.29, 127.91, 127.63, 127.27, 122.52, 121.11, 120.81,
118.82, 114.37, 114.31, 110.90, 71.52, 68.28, 68.00, 67.17, 65.70,
63.39, 52.21, 29.40, 29.36, 29.26, 29.17, 29.02, 28.60, 28.48,
25.90, 25.76, 25.62, 14.24. Anal. Calcd for C146H88N2O17
(2142.30): C, 81.86; H, 4.14; N, 1.31%. Found: C, 81.91; H,
4.32; N, 1.32%.
gave pure
6 (105 mg, 21%). VIS (lmax in nm (e in
dm3 mol21 cm21), CH2Cl2): 426 (3490), 456 (2300), 687
(190). 1H NMR (200 MHz, CDCl3): d 9.03 (t, 4 arom. H),
8.99 (t, 8 arom. H), 8.96 (t, 2 arom. H), 8.63 (t, 16 arom. H),
8.45 (d, 8 arom. H), 8.41 (d, 20 arom. H), 8.13 (d, 68 arom. H),
8.12 (d, 32 arom. H), 7.71 (d, 64 arom. H), 7.65 (d, 64 arom. H),
7.61 (64 arom. H), 7.30 (d, 64 arom. H), 6.95 (d, 68 arom. H),
4.53 (t, 4 H, C60CCO2CH2), 4.36 (t, 64 H, isoph-CO2CH2), 4.02
(t, 68 H, CH2O), 1.9–1.6 (m, 136 H, CO2CH2CH2 and
CH2CH2O), 1.6–1.2 (m, 392 aliph. H). Anal. Calcd for
C1289H1146N32O226 (20701.31): C, 74.79; H, 5.58; N, 2.17%.
Found: C, 74.69; H, 5.51; 2.18%.
Compound 33. Ethyl malonyl chloride (31) (2.39 g,
15.9 mmol) was added to
a suspension of 32 (3.86 g,
Compound 35. To a mixture of 33 (83 mg, 0.236 mmol) in
CH2Cl2 (5 ml) cooled to 0 uC were added a solution of DPTS
(40 mg, 0.136 mmol), DCC (126 mg, 0.611 mmol) and 4-PPy
(spatula tip) in CH2Cl2 (5 ml), and then a solution of 23
(547 mg, 0.235 mmol) in CH2Cl2 (10 ml). The mixture was
stirred at room temperature for 18 h, and evaporated to
dryness. Purification of the solid residue by CC (CH2Cl2–
AcOEt 10 : 0.5) gave pure 35 (625 mg, 100%). 1H NMR
(200 MHz, CDCl3): d 8.94 (t, 1 arom. H), 8.64 (t, 2 arom. H),
8.36 (d, 2 arom. H), 8.18 (d, 2 arom. H), 8.14 (d, 8 arom. H),
8.12 (d, 4 arom. H), 7.74 (d, 8 arom. H), 7.67 (d, 8 arom. H),
7.63 (d, 8 arom. H), 7.32 (d, 8 arom. H), 7.00 (d, 2 arom. H),
6.97 (d, 8 arom. H), 4.37 (t, 8 H, isoph-CO2CH2), 4.21 (m, 2 H,
CO2CH2CH3), 4.18 (t, 2 H, mal-CO2CH2), 4.04 (t, 10 H,
CH2O), 3.38 (s, 2 H, O2CCH2CO2), 1.9–1.6 (m, 20 H,
CO2CH2CH2 and CH2CH2O), 1.6–1.3 (m, 52 aliph. H), 1.28
(t, 3 H, CH3). Anal. Calcd for C162H160N4O31 (2659.05): C,
73.18; H, 6.06; N, 2.11%. Found: C, 73.29; H, 6.13; N, 2.10%.
16.2 mmol) in CH2Cl2 (50 ml). To this mixture was added a
solution of Et3N (1.60 g, 15.8 mmol) in CH2Cl2 (10 ml). The
mixture was stirred at room temperature for 18 h, and
evaporated to dryness. Purification of the solid residue by
CC (CH2Cl2–AcOEt 10 : 0.4) gave pure 33 (2.27 g, 41%).
Tm~88 uC. 1H NMR (200 MHz, CDCl3): d 12.22 (br, 1 H,
CO2H), 8.03 (d, 2 arom. H), 6.90 (d, 2 arom. H), 4.18 (m, 2 H,
CO2CH2CH3), 4.14 (t, 2 H, CO2CH2), 3.99 (t, 2 H, CH2O), 3.36
(s, 2 H, O2CCH2CO2), 1.79 (m, 2 H, CH2CH2O), 1.67 (m, 2 H,
CO2CH2CH2), 1.6–1.4 (m, 4 aliph. H), 1.25 (t, 3 H, CH3). 13
C
NMR (50 MHz, CDCl3): d 171.85, 166.63, 166.54, 163.44,
132.19, 121.35, 114.02, 67.85, 65.29, 61.40, 41.49, 28.79, 28.23,
25.47, 25.41, 13.92. Anal. Calcd for C18H24O7 (352.38): C,
61.35, H, 6.86%. Found: C, 61.36, H, 7.03%.
Compound 34. To a mixture of 33 (123 mg, 0.349 mmol) in
CH2Cl2 (5 ml) cooled to 0 uC were added a solution of DPTS
(70 mg, 0.238 mmol), DCC (180 mg, 0.872 mmol) and 4-PPy
(spatula tip) in CH2Cl2 (5 ml), and then a solution of 20
(380 mg, 0.349 mmol) in CH2Cl2 (10 ml). The mixture was
stirred at room temperature for 18 h, and evaporated to
dryness. Purification of the solid residue by CC (CH2Cl2–
AcOEt 10 : 0.25) gave pure 34 (480 mg, 97%). 1H NMR
(200 MHz, CDCl3): d 8.60 (t, 1 arom. H), 8.15 (d, 6 arom. H),
8.06 (d, 2 arom. H), 7.75 (d, 4 arom. H), 7.68 (d, 4 arom. H),
7.64 (d, 4 arom. H), 7.33 (d, 4 arom. H), 6.98 (d, 6 arom. H),
4.35 (t, 4 H, isoph-CO2CH2), 4.21 (m, 2 H, CO2CH2CH3), 4.18
(t, 2 H, mal-CO2CH2), 4.08 (t, 2 H, (CH2)5CH2O), 4.04 (t, 4 H,
(CH2)9CH2O), 3.38 (s, 2 H, O2CCH2CO2), 1.9–1.6 (m, 12 H,
CO2CH2CH2 and CH2CH2O), 1.6–1.3 (m, 28 aliph. H), 1.29 (t,
3 H, CH3). 13C NMR (50 MHz, CDCl3): d 166.59, 166.51,
164.96, 164.69, 164.42, 163.66, 163.58, 151.46, 150.96, 144.69,
136.51, 132.52, 132.32, 132.22, 128.21, 127.80, 127.54, 127.21,
122.46, 121.05, 120.69, 118.77, 114.31, 114.25, 110.82, 68.21,
68.00, 65.64, 65.27, 61.40, 41.54, 29.34, 29.29, 29.20, 29.11,
28.96, 28.82, 28.52, 28.26, 25.83, 25.50, 25.44, 13.98. Anal.
Calcd for C86H90N2O17 (1423.66): C, 72.56; H, 6.37; N, 1.97%.
Found: C, 72.42; H, 6.36; N, 1.95%.
Compound 8. To a solution of C60 (190 mg, 0.264 mmol) in
toluene (200 ml) were added a solution of 35 (350 mg,
0.132 mmol) in CH2Cl2 (5 ml), a solution of iodine (33 mg,
0.130 mmol) in CH2Cl2 (5 ml) and DBU (40 mg, 0.263 mmol).
The mixture was stirred at room temperature for 18 h, and
evaporated to dryness. Purification of the solid residue by CC
(first with toluene to eliminate unreacted C60, and then with
CH2Cl2–AcOEt 10 : 0.15) and precipitation (dissolution in
CH2Cl2 and precipitation by pouring the solution into
acetone) gave pure 8 (240 mg, 54%). VIS (lmax in nm (e in
dm3 mol21 cm21), CH2Cl2): 426 (2800), 489 (1630), 687 (210).
1H NMR (200 MHz, CDCl3): d 8.94 (t, 1 arom. H), 8.64 (t, 2
arom. H), 8.35 (d, 2 arom. H), 8.16 (d, 2 arom. H), 8.14 (d, 8
arom. H), 8.12 (d, 4 arom. H), 7.73 (d, 8 arom. H), 7.67 (d, 8
arom. H), 7.62 (d, 8 arom. H), 7.31 (d, 8 arom. H), 6.99 (d, 2
arom. H), 6.97 (d, 8 arom. H), 4.56 (m, 2 H, CO2CH2CH3),
4.54 (t, 2 H, C60CCO2CH2), 4.37 (t, 8 H, isoph-CO2CH2), 4.03
(t, 10 H, CH2O), 2.0–1.6 (m, 20 H, CO2CH2CH2 and
CH2CH2O), 1.48 (t, 3 H, CH3), 1.6–1.3 (m, 52 aliph. H).
Anal. Calcd for C222H158N4O31 (3377.70): C, 78.94; H, 4.71; N,
1.66%. Found: C, 79.04; H, 4.81; N, 1.66%.
Compound 7. To a solution of C60 (300 mg, 0.416 mmol) in
toluene (250 ml) were added a solution of 34 (297 mg,
2830
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Acknowledgements
RD acknowledges the Swiss National Science Foundation for
financial support (grant no 20-58956.99). The authors thank
P. Masson for his help in the molecular simulation studies . The
French–Swiss international program of scientific collaboration
PICS No. 742 is gratefully acknowledged.
15 T. Chuard and R. Deschenaux, Helv. Chim. Acta, 1996, 79, 736.
16 R. Deschenaux, M. Even and D. Guillon, Chem. Commun., 1998,
537.
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