Liquid-Crystalline Tris[60]fullerodendrimers - The Journal of Organic

Article Cite This: J. Org. Chem. 2018, 83, 3208−3219

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Liquid-Crystalline Tris[60]fullerodendrimers Pauline Pieper,† Virginie Russo,† Benoît Heinrich,‡ Bertrand Donnio,*,‡ and Robert Deschenaux*,† †

Institut de Chimie, Université de Neuchâtel, Avenue de Bellevaux 51, 2000 Neuchâtel, Switzerland Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504, CNRS-Université de Strasbourg, 23 rue du Loess, BP43, 67034 CEDEX 2 Strasbourg, France

‡

S Supporting Information *

ABSTRACT: Liquid-crystalline tris[60]fullerodendrimers based on first- and second-generation poly(arylester)dendrons carrying cyanobiphenyl mesogens were synthesized for the first time by the olefin cross-metathesis reaction between type I (terminal) and type II (α,β-unsaturated carbonyl) olefinic precursors, using a second-generation Grubbs or Hoveyda− Grubbs catalyst. The modular synthetic approach developed here also allowed the selective preparation of the [60]fullerene-free, mono[60]fullerodendrimer, and bis[60]fullerodendrimer derivatives from the appropriate precursors. As revealed by polarized optical microscopy, differential scanning calorimetry, and small-angle X-ray scattering, all of the materials displayed liquid-crystalline properties. In agreement with the nature of the dendritic building blocks, the emergence of lamellar mesophases (smectic C and/or smectic A phases), with the segregation of the various constitutive parts, was systematically observed. The small variation of the mesomorphic temperature range and of the mesophase stability suggested that the mesomorphism is essentially dominated by the dendrimer itself and is regulated by a subtle adaptive mechanism, in which the proportion of monolayering and bilayering arrangements of the multisegregated lamellar mesophases is modified in order to compensate the space requirements of each of the elementary building blocks, namely, the [60]fullerene units, the cyanobiphenyl mesogens, and the dendritic matrix.

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INTRODUCTION The design of mesomorphic [60]fullerenes is receiving great attention in the scientific community as such materials combine the electrochemical1 and photophysical2 properties of [60]fullerene (C60) with the self-organization behavior of liquid crystals. Such a combination of properties provides an original concept for the design of complex structures based on C60 for the development of novel supramolecular devices.3 A rich variety of examples is available in the literature, including liquidcrystalline [60]fullerene-oligophenylenevinylene conjugates,4 [60]fullerene-based bent-core liquid crystals,5 amphiphilic oligothiophene-[60]fullerene dyads,6 and alkylated [60]fullerenes.7 The electro-optical properties of liquid-crystalline fullerenes, such as electron transport, were investigated in columnar8 and smectic phases.6,9 In order to improve the effectiveness of [60]fullerene-based devices (photoactive dyads,10 polyads,11 photovoltaic cells12), materials containing two,13 three,14 four,15 or more16 C60 units were synthesized. However, in the case of liquid crystals, the design of mesomorphic materials containing more than one C60 unit is still an intellectual and difficult challenge.4,17 This is the consequence of the large isotropic volume of [60]fullerene, which has to be overcome to generate mesomorphism. For example, in a recent report,4 a star-shaped oligophenylenevinylene mesogen covalently attached to one C60 unit selforganized into a columnar hexagonal phase. However, when three C 60 units were connected to the mesogen, no mesomorphism was observed. © 2018 American Chemical Society

On the other hand, the modular nature and structural features of liquid-crystalline dendrimers (generation, multiplicity of the branches, connectivity, flexibility)18 provided effective ways to induce liquid-crystalline properties while increasing the content of C60 in the molecular framework. Indeed, in a previous study, we reported the design, synthesis, and supramolecular organization of bis[60]fullerodendrimers bearing poly(arylesters) dendrons functionalized with cyanobiphenyl mesogens.19 The synthetic approach was based on the olefin cross-metathesis reaction,20 which allowed the connection of type I (terminal olefin) and type II (α,β-unsaturated carbonyl olefin) olefinic mono[60]fullerodendrimers under standard reaction conditions to give the desired bis[60]fullerodendrimers.19 The observed liquid-crystalline properties (smectic A, smectic C, and nematic phases) were in agreement with the structure and nature of the dendromesogens used as mesomorphic promoters. The stability and structural parameters of the mesophases were found to depend on both the subtle interplay of attractive interactions between neighboring fullerenes and on the volume occupied by the dendrimers and the fullerenes. The modular synthetic approach developed for the bis[60]fullerodendrimers19 could be implemented for the design of more intricate multi[60]fullerodendrimer structures with liquid-crystalline properties. For instance, tris[60]fullerodendrimers could be prepared by connecting three Received: January 11, 2018 Published: March 1, 2018 3208

DOI: 10.1021/acs.joc.8b00093 J. Org. Chem. 2018, 83, 3208−3219

Article

The Journal of Organic Chemistry

Figure 1. Molecular structures of first- (1) and second (5)-generation tris[60]fullerodendrimers and of their related mono-, bis-, and free[60]fullerene homologues.

and convenient method to attach C60 to an organic framework via malonate building blocks and was applied for the preparation of the methanofullerene precursors. Then, the tris[60]fullerodendrimers (and their homologues) were synthesized by connecting type I and type II olefin-containing malonates and/or methanofullerenes by the Ru-catalyzed olefin cross-metathesis reaction. The central malonate (13) and corresponding methanofullerene unit (14) were derived from type I olefins, whereas the end branches without (9 and 11) and with (10 and 12) C60 were derived from α,β-unsaturated carbonyl olefins. Our synthetic methodology is summarized in Table 1. The synthesis of the trismalonates (4 and 8) and mono[60]fullerodendrimers (3 and 7), bis[60]fullerodendrimers (2 and 6), and tris[60]fullerodendrimers (1 and 5) required the synthesis of their olefinic precursors (Table 1 and Scheme 1). First- and second-generation type II olefins 9 and 11 were synthesized following a method recently reported by our group.19 Type I olefin 13 was prepared by the esterification reaction of 10-undecen-1-ol with malonyl chloride (Scheme 1). The cyclopropanation reaction of C60 with

building blocks, each of which containing one C60 unit, via the olefin cross-metathesis reaction. If the target materials can be obtained in this way, the olefin cross-metathesis would therefore be a reaction of choice for the elaboration of a multitude of fullerene-rich liquid-crystalline and dendrimeric materials, as well as other functional materials, for the development of the nanotechnologies by the bottom-up approach. We describe, herein, the synthesis, characterization, liquidcrystalline properties, and supramolecular organization of firstand second-generation tris[60]fullerodendrimers and of the homologous trismalonates and mono- and bis[60]fullerene derivatives (Figure 1). The target compounds were obtained by assembling the desired olefinic precursors via the olefin crossmetathesis reaction.

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RESULTS AND DISCUSSION Synthetic Methodology. The preparation of the target fullerodendrimers was based on the [60]fullerene cyclopropanation reaction21 and the olefin cross-metathesis reaction.20 The Bingel cyclopropanation reaction is a reliable 3209


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The Journal of Organic Chemistry Table 1. Synthetic Methodologya

a

For structures 1−8, see Figure 1.

Scheme 1. Synthesis of Tris[60]fullerodendrimers 1 and 5a

Reagents and conditions: (i) malonyl chloride, pyridine, dry CH2Cl2, 0 °C to rt, 12 h, 84%; (ii) C60, I2, DBU, toluene, rt, 4 h, 43%; (iii) 10 or 12, Ru catalyst, dry CH2Cl2, 40 °C, 8 h, 38−27%.

a

olefins in dry CH2Cl2 was stirred at 40 °C for 8 h in the presence of a ruthenium catalyst (0.1 equiv) and CuI.22 Second-generation Grubbs23 and Hoveyda−Grubbs24 catalysts were both tested (Table 1). The second-generation Grubbs catalyst led to the formation of compounds 1−4 in 37−45%

malonates 9, 11, and 13 under modified Bingel conditions21b,c led to the methanofullerene derivatives 10, 12, and 14. Compounds 1−8 were synthesized via the olefin crossmetathesis reaction as shown in Scheme 1. In a typical procedure, a mixture of type I (1 equiv) and type II (2.5 equiv) 3210


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Figure 2. 1H NMR spectra (CD2Cl2, 400 MHz) of the first-generation dendrimers 1−4.

yields. Under such conditions, the tris[60]fullerene 5 was formed in 12% yield only. However, the Hoveyda−Grubbs II catalyst proved to be more efficient for the synthesis of 5 (27%) and was therefore also used for the other second-generation materials (6 21%, 7 25%, and 8 20%). The moderate yields observed can be explained by the purification process, which required column chromatography, gel permeation chromatography, and precipitation (see Supporting Information for details). Finally, the solubility of the tris[60]fullerodendrimers 1 and 5 in common organic solvents was similar to one of their corresponding malonates 4 and 8. The structure of the compounds was confirmed by 1H NMR spectroscopy (Figure 2) by (i) the emergence of two doublets of triplets at δ = 7.00 and 5.84 ppm, which are characteristic of the internal olefinic protons and (ii) the value of 15.7 Hz of the coupling constant between the two olefinic protons Hd and He, which confirmed the E-configuration of the newly formed carbon−carbon double bonds. In the 1H NMR spectra of mono- (3), bis- (2), and tris[60]fullerodendrimers (1), the disappearance of the malonate signals (Hb and Hg) and upshielding shift of the methylenic protons Ha, Hc, and Hf indicated the incorporation of C60 units onto the malonates (Figure 2). Similar results were obtained for second-generation materials 5−8. The UV−vis spectra of 1−3 exhibited absorption peaks, which are characteristic of the methanofullerenes25 at 426, 485, and 685 nm (Figure 3). A linear correlation was observed for the molar extinction coefficients (ε) measured at 426 nm with respect to the number of C60 per molecule. Similar results were obtained for 5−7. Liquid-Crystalline Properties. The mesomorphic and thermal properties of compounds 1−8 were investigated by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The phase-transition temperatures and enthalpies are reported in Table 2. The thermal behavior of type II olefins 9−12 was not investigated as such acrylate derivatives readily polymerize when heated.19,20e Olefins 13 and 14 are, as expected, nonmesomorphic materials.

Figure 3. UV−Vis spectra of 1 (red line), 2 (blue line), and 3 (green line) in CH2Cl2.

All of the cross-metathesis compounds 1−8 showed liquidcrystalline behavior and displayed smectic phases in agreement with the structure and nature of the molecules that carry cyanobiphenyl mesogens. Trismalonate 4, mono[60]fullerodendrimer 3, and bis[60]fullerodendrimer 2 displayed smectic A (focal-conic fan and homeotropic textures) and smectic C phases (focal-conic fan and schlieren textures) (Figures 4 and 5). Trismalonate 8 gave rise to the smectic A phase (focal-conic fan and homeotropic textures, Figure S29). No typical textures were observed for the tris[60]fullerodendrimers 1 and 5, mono[60]fullerodendrimer 7, and bis[60]fullerodendrimer 6 even when the samples were annealed for several hours near the clearing temperature (Figures S30−S33). This behavior is, most likely, due to the high viscosity of the samples. However, by analogy with their precursors and with the previously reported bis[60]fullerodendrimers,19 the mesophases observed below the isotropic temperature are likely smectic A phases.26 3211


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The Journal of Organic Chemistry Table 2. Phase-Transition Temperatures and Enthalpies of Compounds 1−8 compound

Tsol [°C]a

1 (G1, tris-C60) 2 (G1, bis-C60)

41 36

3 (G1, mono-C60)

29

4 (G1, trismalonate)

17

5 6 7 8

(G2, (G2, (G2, (G2,

tris-C60) bis-C60) mono-C60) trismalonate)

43 39 30

transition

T [°C]

SmA → I SmC → SmA SmA → I SmC → SmA SmA → I SmC → SmA SmA → I SmA → I SmA → I SmA → I SmA → I

150 123b 134 90b 136 81b 147 177 160 158 168

ΔH [kJ mol−1] 20.3 25.6 20.4 15.9 36.3 27.3 18.6 18.4

Figure 6. Phase diagram of the G1 (1−4) and G2 (5−8) dendromesogens (glassy mesophases for 1, 2, 3, and 5; amorphous glasses for 6−8; semicrystalline solid for 4).

a

Tsol = solid-phase-transition temperature: glassy mesophase for 1, 2, 3, and 5; amorphous glass for 6−8; semicrystalline solid for 4. SmA = smectic A phase. SmC = smectic C phase. I = isotropic liquid. b Observed by POM. Temperatures (in °C) are given as the onset of the peaks obtained during the second heating run.

compounds 1−8, a small destabilization of the mesophase is observed upon the addition of the first two C60 units within the dendritic framework; then, a complete restoration of the mesomorphism displayed by the trismalonates 4 and 8 is achieved upon the insertion of the third C60 unit, [with even a small enhancement of the mesophase stability (by +3 °C for ″4 → 1″ and +9 °C for ″8 → 5″)]. This result suggests that the mesomorphism in this class of compounds is essentially dominated by the dendrimer itself (dendritic matrix and the terminal cyanobiphenyl mesogens) and further demonstrates its great capacity to incorporate and tolerate (up to three) bulky [60]fullerene components without major alteration of the mesomorphism. Small-Angle X-ray Scattering Studies. The self-organized structures were investigated by small-angle X-ray scattering (SAXS) in combination with partial volume calculation and room-temperature grazing-incidence wide-angle X-ray scattering (GIWAXS) on tens-nanometer scale films deposited on a Si wafer. The SAXS experiments were carried out at various temperatures (Figure 7 and Table 3). The pristine dendrimers are semicrystalline or in a glassy state with non-well-developed self-organized structures as revealed by SAXS patterns, which solely exhibit small- and large-angle diffuse scatterings. Upon heating, all terms of the series flow in fluid smectic phases that extend from ca. 50 °C to the clearing points ranging between 150 and 180 °C (Figure 6). All dendrimers display a smectic A phase, which is preceded by a smectic C phase for the three G1 dendrimers with the lowest C60 content. Consistently, all SAXS patterns recorded in the fluid mesophases are typical of smectic phases with several sharp reflections (00l) and up to four reflections in the synchrotron patterns (Figure 7, Figures S35− S37 and S39) and with the broad wide-angle scattering maximum around 4.5 Å from lateral distances between chains (hch) and mesogens (hmes). In addition, the adducts with a high [60]fullerene content give rise to a scattering signal, hful, around 10 Å due to close packing of the [60]fullerene groups, and all G2 dendrimers show a broad signal D at 20−21 Å attributed to close distances between neighboring protean-like dendrimeric units (with correlation lengths of ca. 3−4 nm, as determined by the Scherrer equation). The fluid SmC phase of the G1 adducts freezes when cooling to room temperature, whereby the tilt angle ψ was determined in the frozen smectic state with GIWAXS experiments on thin films (ψ = 32° for 3 and ψ = 27° for 2, as obtained from the

Figure 4. Thermal-polarized optical micrographs of the focal-conic textures and homeotropic areas at 146 °C (left) and the focal-conic and schlieren textures at 80 °C (right) displayed by 4 in the smectic A and C phases, respectively.

Figure 5. Thermal-polarized optical micrographs of (a and b) the focal-conic fan texture and homeotropic area displayed by 3 and 2 in the smectic A at 134 and 132 °C, respectively; (c and d) the focalconic and schlieren textures displayed by 3 and 2 in the smectic C at 89 and 122 °C, respectively.

It is very unexpected, at first sight, that such small differences are observed in the thermal behavior of this family of compounds, yet differing by the dendritic generation on the one hand and by the [60]fullerene content on the other hand. The main effect, as often observed with liquid-crystalline dendrimers,18 is the enhancement of the stability of the mesophases upon increasing the generation (Figure 6). For 3212


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Figure 7. Four representative SAXS patterns of compound 5 at various temperatures: (a) at 20 °C in the pristine state (amorphous), (b) at 110 °C in the SmA phase, (c) at 110 °C in the SmA phase (Synchrotron SOLEIL, line SWING, bulk), and (d) at 20 °C cooling in the SmA phase. GIWAXS pattern of 5 at 20 °C in the SmA phase (Synchrotron PLS-II, line 9A, thin film).

angle between directions of hmes and the c*-axis, Figures S35 and S36). In the frozen SmA phase of compound 1, there is, of course, no tilt, but the lamellar spots have an elongated shape, possibly caused by layer undulations reminiscent of the SmC phase. Among the G2 dendrimers, only the adduct with the highest [60]fullerene content (compound 5) exhibits a SmA phase that freezes into a glassy state, as shown by SAXS and GIWAXS patterns (Figure 7). For the other G2 dendrimers, the lamellar reflections vanish with cooling from the fluid SmA phase to room temperature, which could thus be considered as conformationally disordered solids or amorphous glasses. Yet, the GIWAXS pattern on thin films of compound 7 shows the orientation of scattering signals at room temperature, implying that the alignment was maintained from the fluid SmA phase and that no change of the molecular organization occurred with cooling the sample.

The disappearance of long-range correlated lamellae is probably due to alteration of the regularity of layers during stiffening. GIWAXS patterns of both adducts further show that the scattering signal D spreads in an extended bow making a large angle (45° and higher) with the direction of lateral distances inside layers, given by the (hmes + hch) scattering maximum, meaning that interacting dendritic units are shifted relative to each other. Such shifts between neighboring dendrimeric units should have an impact on the lateral association of aliphatic spacers and mesogens and might explain the vanishing of the long-range layering at low temperatures. The nanosegregation of the sequence of molecular segments into a multilayered smectic phase requires that the different sizes of the individual segments be compromised to a common molecular area representing the degree of lateral expansion. This area, Amol, can be experimentally accessed by the ratio 3213


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+ σlin ≈ 108 Å2 (σful ≈ 86 Å2). Amol for the G1 trismalonate 4 is about half this value, and swelling must be achieved either by a substantial lateral expansion of the lamellae or by the shifted packing of the [60]fullerene groups into multilayers. The latter is energetically preferable, since it is not as detrimental to nanosegregation as the former, providing that the insertion of the [60]fullerene multilayer is sterically possible. Such an effect depends on the [60]fullerene content, and the functionalization of one of the three malonate sites in the G1 dendrimer series increases the molecular area Amol by only 5% (to ca. 58 Å2). Consequently, for this adduct, τ turns out to be almost the same as for the [60]fullerene-free malonate (Table 3), and the presumed double-layer formation logically combines with the promotion of the SmC phase, owing to the expected tilt induction from shifts between neighboring molecules (the tilt angle ψ ≈ 32° being directly accessed from the roomtemperature GIWAXS pattern, Figure S35). This modest swelling implies that the additional substituent volume distributes between linear segments over a large portion of the sublayer, which is moreover confirmed by the absence of a correlation signal between [60]fullerene groups in the SAXS patterns (Figure S36). The successive C60 addition of the two and three malonate sites substantially expand Amol (to ca. 71 and 81 Å2, respectively), which stays, however, below the total area requirement of the linear segment and [60]fullerene (σful + σlin ≈ 108 Å2). A less compact multilayering with τ reduced down to 0.56, and a further extension of the SmC range occurs for the bis[60]fullerene adduct 2. For the tris[60]fullerene adduct 1, a layer expansion of 50% and a τ value of 0.21 involve a change of the predominant mesogen association from bilayer to monolayer, while the irregular layering results in the disappearance of the long-range correlated tilt angle and in replacement of the SmC by the SmA phase. Neighboring [60]fullerenes are therefore still loosely intercalated, though the appearance of a broad scattering maximum, hful ≈ 10 Å, reveals the onset of positional correlations between them. Thus, the tilting decreases in the bis[60]fullerene adduct (ψ ≈ 27°) and cancels in the tris[60]fullerene adduct (leaving orientational fluctuations), while the proportion of bilayers τ reduces from 0.8 in the neat ligand to 0.2 in the ultimate adduct. In contrast to the G1 adducts, for which the insertion of C60 causes substantial lateral expansion and favors the evolution of the cyanobiphenylenes arrangement into monolayers, Amol for the G2 adduct already equals or slightly exceeds σful + σlin, so that the self-assembling of the corresponding G2 adducts (5−7) into multilayered smectic phases does not need any further lateral expansion. The improved compactness with higher [60]fullerene contents with the formation of a compact strata of aggregated [60]fullerenes arises from the wedge-shape of dendritic moieties by small shifts between neighboring molecules, the free space between wedges being filled with the molten aliphatic spacers. Accordingly, a variation of τ in the G2 series is indeed found to be small, confirming that the arrangement of the dendrimeric units and mesogens (thus essentially remaining organized into bilayers) is hardly affected by the swelling of the linear segment−fullerene layer (supported by the GIWAXS pattern of adduct 5).

Table 3. Structural Characteristics of the SmA/SmC Phases Displayed by Compounds 1−8a T [°C] SmA SmA

20 110

SmC SmC

20 110

SmC SmA

20 110

SmA

110

SmA SmA

20 110

SmA

110

SmA

110

SmA

110

Vmol [Å3] (ρ [g cm−3])

Amol [Å3]

ames [Å3]

τ

1.0 1.0

81 84

40.4 42.1

0.16 0.21

1.0 0.2

71 72

35.7 36.1

0.56 0.50

1.0 0.2

58 57

29.1 28.7

0.88 0.78

0.2

55

27.3

0.84

1.0 0.2

114 121

28.4 30.2

0.71 0.72

0.2

117

29.2

0.76

0.2

108

27.1

0.85

1.0

110

27.5

0.83

d [Å]

Compound 1 7125 (∼1.31) 88.2 ± 7606 (∼1.22) 90.3 ± Compound 2 6420 (∼1.27) 90.0 ± 6853 (∼1.19) 95.0 ± Compound 3 5715 (∼1.21) 98.2 ± 6101 (∼1.14) 106.3 ± Compound 4 5348 (∼1.07) 97.8 ± Compound 5 10635 (∼1.26) 93.7 ± 11353 (∼1.18) 94.0 ± Compound 6 10600 (∼1.15) 90.8 ± Compound 7 9848 (∼1.12) 90.9 ± Compound 8 9095 (∼1.08) 82.8 ±

a

SmA/C: smectic A/C phase. Vmol: calculated molecular volume (rounded value). ρ: density. d: lamellar periodicity. Amol: molecular area (Amol = Vmol/d). τ: bilayer ratio calculated from the mesogenic area, ames = 2Amol/nmes [in which nmes is the number of mesogens per molecule (nmes = 4 for G1 and nmes = 8 for G2)],27 and from the natural cross-sectional area of mesogens, σmes ≈ 23.5 Å2 at 110 °C (≈ 22 Å2 at 20 °C), according to the equation τ = 2 − [ames × cos(ψ)/σmes]. Tilt angles ψ were determined from room-temperature GIWAXS patterns. The volume of C60 was deduced from its crystalline structure [facecentered cubic (fcc) crystalline system with a = 14.15 Å, ρ = 1.70 g cm−3, Z = 4];28 volume of C60 = 705 Å3. For compound 2, the tilt angle was estimated to be 15°.

between the molecular volume, Vmol, and the layer periodicity, d, converted into molecular area per mesogen, ames, and, as relevant for cyanobiphenyl-ended mesogens, to the bilayering ratio parameter τ. Depending on the constrains of the selfassembling, cyanobiphenyl-ended mesogens may indeed associate (i) head-to-tail into monolayer (τ = 0, ames = 2σmes, σmes being the natural cross-sectional area of the end mesogens), (ii) tip-to-tip into bilayer (τ = 1, ames = σmes), or (iii) into any intermediate configurations.29 This calculation gives the same τ of ca. 0.85 for both the trismalonates 4 (G1) and 8 (G2), which probably reflects the optimal proportion of bilayers for this specific couple mesogen/aliphatic spacer, i.e., similar cross sections (Table 3 and Figure 8). A substantially lower value of 0.3 was, however, found for a previous G2 dendrimer differing from the present one only by its shorter linear segment.19 This difference comes, most probably, from the wedge-shaped dendrimeric units; with a connection through the short linear segment, these bulky groups would be forced to face and to spread out of the lamellae. With the longer linear segment, they could form a more compact shifted packing, which would be in agreement with GIWAXS patterns. The connection of [60]fullerene to the malonate sites obviously modifies this relationship and the molecular packing. The formation of the multilayered smectic phase for the C60 adducts implies the swelling of the linear segment layer to match the overall cross sections of C60 and linear segment: σful

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CONCLUSIONS The first tris[60]fullerodendrimers were successfully synthesized. The modular synthetic approach developed allowed access to the homologous trismalonates, mono[60]fullerene, and bis[60]fullerene derivatives. The first- and second3214


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Figure 8. Schematic representations of the supramolecular multisegregated lamellar organizations (T = 110 °C) of the malonate ligands and corresponding [60]fullerene adducts with one to three [60]fullerene groups, of first (top)- and second (bottom)-generations. [60]Fullerenes are represented by black spheres, and cyanobiphenyl mesogens are represented by blue (front row) and gray (back row) cylinders. The thickness of the fullerene rows (ca. 10 Å) are about twice the mesogen rows (ca. 4.6 Å). The molten aliphatic spacers and dendritic segments, which fill the white space, are omitted for clarity. on a PerkinElmer LAMBDA 25 spectrophotometer using precision cells made of quartz (1 cm). 1H and 13C NMR spectra were recorded on a Bruker AMX 400 spectrometer with the solvent as an internal reference. Elemental analyses were performed by the Mikroelementarisches Laboratorium, ETH Zürich. Compound 13. To a solution of 10-undecen-1-ol (3.00 g, 17.6 mmol) and pyridine (1.39 g, 17.6 mmol) in dry CH2Cl2 (150 mL) cooled to 0 °C was added dropwise malonyl chloride (1.24 g, 8.80 mmol). The mixture was stirred at room temperature for 12 h and evaporated to dryness. Purification of the solid residue by column chromatography (CH2Cl2/cyclohexane 50:50) gave 13 (3.03 g, 7.41 mmol, 84%). 1H NMR (δ in ppm, 400 MHz, CD2Cl2): 5.82 (ddt, 2H, 2 × CH2CHCH2, 3Jtrans = 16.94 Hz, 3Jcis = 10.18 Hz, 3J = 6.65 Hz), 4.99 (d, 2H, CH2CHCH2, 3Jtrans = 17.11 Hz), 4.92 (d, 2H, CH2 CHCH2, 3Jcis = 10.13 Hz), 4.10 (t, 4H, 2 × O2CCH2CO2CH2), 3.33 (s, 2H, O2CCH2CO2), 2.04 (q, 4H, 2 × CH2CHCH2), 1.63 (p, 4H, 2 × CH2CHCH2CH2), 1.38−1.28 (m, 24H, aliphatic H). 13C NMR (δ in ppm, 100 MHz, CD2Cl2): 167.2, 139.8, 114.4, 66.1, 42.3, 34.4, 30.1, 30.0, 29.8, 29.7, 29.55, 29.1, 26.4. MS [MALDI(+)]: 431.32 [M + Na]+. Anal. Calcd for C25H44O4 (408.62): C, 73.49; H, 10.85%. Found: C, 73.40; H, 11.14%. Compound 14. To a solution of C60 (0.58 g, 8.08 × 10−1 mmol) in toluene (400 mL) were added (after complete dissolution of C60), in the following order, 13 (0.30 g, 7.34 × 10−1 mmol), iodine (0.22 g, 8.81 × 10−1 mmol), and 1,8-diazabicyclo[5.4.0]undec-7-ene (0.22 g,

generation poly(arylester) dendrons carrying cyanobiphenyl mesogens were used as liquid-crystalline promoters. All compounds showed multilayered smectic phases, whose emergence is promoted by the presence of the strongly smectogenic terminal cyanobiphenyl groups and by the strong tendency of the different molecular constituents to segregate in space. The mesophase cohesion is due to the strong interactions that prevail in the sublayer between the C60 moieties and is regulated by a subtle adaptive mechanism, in which the proportion of monolayering and bilayering arrangements of the mesogenic end groups is modified to compensate for the space requirements of the bulky elementary building blocks, namely, the [60]fullerene units and the dendritic matrix. The results reported herein open avenues to the elaboration of novel supramolecular devices based on [60]fullerene-rich liquid-crystalline materials as well as other functional materials.

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EXPERIMENTAL SECTION

Materials. Compounds 9−12 were synthesized as described.19 All reactions were carried out under argon. Commercially available reagents were used as received. Dichloromethane was distilled over P2O5 prior to use. Column chromatography used silica gel 60 (63− 200, 60 Å, Brunschwig). UV−Visible absorption spectra were recorded 3215


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6 × CH2CH2OAr and 6 × CO2CH2CH2), 1.63−1.60 (m, 4H, 2 × CH2CH2CHCH), 1.48−1.29 (m, 96H, aliphatic H). 13C NMR (δ in ppm, 100 MHz, CD2Cl2): 167.2, 166.1, 165.5, 165.3, 165.0, 164.5, 164.4, 164.0, 163.9, 152.3, 151.8, 151.2, 146.1, 146.0, 145.8, 145.74, 145.71, 145.4, 145.3, 145.23, 145.16, 145.1, 144.4, 143.64, 143.62, 143.57, 143.54, 143.51, 142.75, 142.6, 142.4, 141.51, 141.50, 139.65, 139.5, 137.3, 133.2, 133.1, 132.9, 132.8, 128.9, 128.2, 128.1, 127.7, 123.1, 121.9, 121.4, 121.0, 119.4, 115.1, 115.0, 111.6, 72.3, 69.1, 69.05, 68.2, 66.3, 66.1, 65.50, 62.15, 53.2, 42.25, 33.0, 30.14, 30.12, 30.10, 30.06, 30.02, 29.97, 29.91, 29.85, 29.83, 29.80, 29.77, 29.71, 29.69, 29.25, 29.20, 29.10, 28.6, 26.61, 26.59, 26.57, 26.53, 26.50, 26.40. MS [MALDI(+)]: 4911.56 [M + Na]+. Anal. Calcd for C327H232N4O42 (4889.43): C, 80.33; H, 4.78; N, 1.15%. Found: C, 80.40; H, 4.85; N, 1.16%. UV−Vis [λmax in nm (ε in l mol−1 cm−1), CH2Cl2]: 426 (5537), 490 (3040), 688 (380). Compound 3. This compound was obtained from 9 (0.15 g, 9.68 × 10−2 mmol), 14 (0.45 × 10−1 g, 4.03 × 10−2 mmol), secondgeneration Grubbs catalyst (0.34 × 10−2 g, 4.03 × 10−3 mmol), and CuI (0.23 × 10−3 g, 1.21 × 10−3 mmol) in CH2Cl2 (10 mL). Yield: 37% (6.21 × 10−2 g, 1.49 × 10−2 mmol). 1H NMR (δ in ppm, 400 MHz, CD2Cl2): 8.55 (br s, 2H, aromatic H), 8.13 (d, 12H, aromatic H), 8.04 (br s, 4H, aromatic H), 7.75 (d, 8H, aromatic H), 7.72 (d, 8H, aromatic H), 7.67 (d, 8H, aromatic H), 7.32 (d, 8H, aromatic H), 6.99 (m, 14H, aromatic H and 2 × CHCHCO2), 5.81 (d, 2H, 2 × CHCHCO 2 , 3 J t r a n s = 15.57 Hz), 4.47 (t, 4H, 2 × CO2CH2CO2CH2CH2), 4.33 (m, 16H, 2 × CHCHCO2CH2CH2, 2 × CHCHCO2CH2 and 4 × ArCO2CH2), 4.10 (t, 4H, 2 × O2CC(C60)CO2CH2), 4.04 (t, 12H, 6 × CH2OAr), 3.38 (s, 4H, 2 × O2CCH2CO2), 2.19 (q, 4H, 2 × CH2CH2CHCH), 1.81−1.75 (m, 24H, 6 × CH2CH2OAr and 6 × CO2CH2CH2), 1.63−1.60 (m, 4H, 2 × CH2CH2CHCH), 1.48−1.29 (m, 96H, aliphatic H). 13C NMR (δ in ppm, 100 MHz, CD2Cl2): 167.0, 166.9, 166.6, 165.5, 165.25, 165.0, 164.5, 164.3, 164.0, 152.2, 151.7, 151.0, 146.2, 146.1, 145.75, 145.7, 145.4, 145.21, 145.18, 145.1, 144.4, 143.6, 143.51, 143.48, 142.7, 142.4, 141.45, 139.5, 137.2, 133.2, 133.0, 132.8, 132.7, 128.8, 128.2, 128.1, 127.7, 123.1, 121.8, 121.3, 121.0, 119.4, 115.0, 114.9, 111.6, 77.4, 69.04, 68.99, 68.0, 66.3, 66.2, 63.7, 62.2, 53.2, 42.0, 32.8, 30.06, 30.04, 30.02, 29.99, 29.95, 29.91, 29.87, 29.79, 29.77, 29.75, 29.7, 29.6, 29.18, 29.16, 29.1, 29.0, 28.6, 26.6, 26.55, 26.52, 26.50, 26.48, 26.3. MS [MALDI(+)]: 4193.55 [M + Na]+. Anal. Calcd for C267H234N4O42 (4170.79): C, 76.89; H, 5.65; N, 1.34%. Found: C, 76.71; H, 5.59; N, 1.29%. UV−Vis [λmax in nm (ε in l mol−1 cm−1), CH2Cl2]: 426 (2536), 490 (1449), 688 (193). Compound 4. This compound was obtained from 9 (0.40 × 10−1 g, 2.58 × 10−2 mmol), 13 (0.44 × 10−2 g, 1.07 × 10−2 mmol), secondgeneration Grubbs catalyst (0.91 × 10−3 g, 1.07 × 10−3 mmol), and CuI (0.61 × 10−4 g, 3.21 × 10−4 mmol) in CH2Cl2 (10 mL). Yield: 45% (1.69 × 10−2 g, 4.89 × 10−3 mmol). 1H NMR (δ in ppm, 400 MHz, CD2Cl2): 8.55 (t, 2H, aromatic H), 8.14 (d, 4H, aromatic H), 8.12 (d, 8H, aromatic H), 8.04 (d, 4H, aromatic H), 7.75 (d, 8H, aromatic H), 7.72 (d, 8H, aromatic H), 7.67 (d, 8H, aromatic H), 7.32 (d, 8H, aromatic H), 7.01 (m, 14H, aromatic H and 2 × CH CHCO2), 5.82 (dt, 2H, CHCHCO2, 3Jtrans = 15.45 Hz, 4J = 1.32 Hz), 4.32 (m, 16H, 2 × CHCHCO2CH2CH2, 2 × CH CHCO 2 CH 2 CH 2 and 4 × ArCO 2 CH 2 ), 4.11 (t, 4H, 2 × O2CCH2CO2CH2), 4.09 (t, 4H, 2 × O2CCH2CO2CH2CH2), 4.04 (t, 12H, 6 × CH2OAr), 3.38 (s, 4H, 2 × O2CCH2CO2), 3.33 (s, 2H, O2CCH2CO2), 2.22 (m, 4H, 2 × CH2CHCH), 1.84−1.75 (m, 20H, 4 × CH2CH2OAr and 6 × CO2CH2CH2), 1.64 (m, 8H, 2 × CH2CH2CHCH and 2 × CH2CH2OAr), 1.48−1.29 (m, 96H, aliphatic H). 13C NMR (δ in ppm, 100 MHz, CD2Cl2): 167.2, 167.0, 166.9, 166.6, 165.5, 165.3, 165.0, 164.5, 164.3, 152.2, 151.8, 151.1, 145.2, 137.2, 133.2, 133.0, 132.8, 132.7, 131.9, 128.8, 128.2, 127.1, 123.1, 121.8, 121.3, 121.0, 119.4, 115.0, 114.9, 111.6, 69.05, 69.0, 66.3, 66.2, 66.1, 63.7, 62.2, 42.2, 41.9, 32.8, 30.02, 30.00, 29.99, 29.95, 29.90, 28.87, 29.8, 29.74, 29.72, 29.68, 29.65, 29.60, 29.58, 29.3, 29.2, 29.03, 29.01, 28.6, 26.6, 26.53, 26.50, 26.49, 26.3. MS [MALDI(+)]: 3474.64 [M + Na]+. Anal. Calcd for C207H236N4O42 (3452.14): C, 72.02; H, 6.89; N, 1.62%. Found: C, 71.90; H, 6.99; N, 1.53%.

1.46 mmol). The mixture was stirred at room temperature for 4 h, filtered through silica, and evaporated to dryness. The solid residue was purified by gel permeation chromatography (Biobeads SX-3, toluene), followed by column chromatography (CH2Cl2), and precipitation (by pouring dropwise a CH2Cl2 solution into cold MeOH) gave 14 (0.35 g, 3.14 × 10−1 mmol, 43%). 1H NMR (δ in ppm, 400 MHz, CD2Cl2): 5.82 (ddt, 2H, 2 × CH2CHCH2, 3Jtrans = 17.11 Hz, 3Jcis = 10.38 Hz, 3J = 6.62 Hz), 4.98 (d, 2H, CH2CHCH2, 3 Jtrans = 17.91 Hz), 4.91 (d, 2H, CH2CHCH2, 3Jcis = 10.28 Hz), 4.47 (t, 4H, 2 × CH2CH2O2CC(C60)CO2), 2.03 (q, 4H, 2 × CH2 CHCH2), 1.83 (p, 4H, 2 × CH2CHCH2CH2), 1.59−1.30 (m, 24H, aliphatic H). 13C NMR (δ in ppm, 100 MHz, CD2Cl2): 164.1, 146.1, 145.77, 145.71, 145.69, 145.38, 145.22, 145.20, 145.10, 144.4, 143.60, 143.53, 143.51, 142.7, 142.4, 141.5, 139.8, 139.5, 114.4, 72.4, 68.0, 53.3, 34.4, 30.14, 30.0, 29.8, 29.7, 29.5, 29.2, 26.6. MS [ESI(+)]: 1149.3 [M + Na]+. Anal. Calcd for C85H42O4 (1127.26): C, 90.57; H, 3.76%. Found: C, 90.53; H, 3.64%. UV−Vis (λmax in nm (ε in l mol−1 cm−1), CH2Cl2): 426 (2660), 489 (1559), 688 (183). General Procedure for the Olefin Cross-Metathesis: Synthesis of Compounds 1−8. A mixture of type I olefin (1 equiv), type II olefin (2.4 equiv), ruthenium carbenoids catalyst (0.1 equiv), and CuI (0.03 equiv) in dry CH2Cl2 was stirred at 40 °C for 8 h under Ar and was evaporated to dryness. Purification of the residue by column chromatography (silica gel, CH2Cl2/EtOAc, 100:0 to 0.5), followed by gel permeation chromatography, (Biobeads SX-1, toluene) and finally by precipitation (dissolution in CH2Cl2 and precipitation by pouring the solution into cold MeOH) gave 1−8. Compound 1. This compound was obtained from 10 (0.18 g, 8.09 × 10−2 mmol), 14 (0.38 × 10−1 g, 3.37 × 10−2 mmol), secondgeneration Grubbs catalyst (0.29 × 10−2 g, 3.37 × 10−3 mmol), and CuI (0.19 × 10−3 g, 1.01 × 10−3 mmol) in CH2Cl2 (10 mL). Yield: 38% (7.23 × 10−2 g, 1.29 × 10−2 mmol). 1H NMR (δ in ppm, 400 MHz, CD2Cl2): 8.55 (br s, 2H, aromatic H), 8.13 (d, 12H, aromatic H), 8.04 (br s, 4H, aromatic H), 7.75 (d, 8H, aromatic H), 7.72 (d, 8H, aromatic H), 7.67 (d, 8H, aromatic H), 7.32 (d, 8H, aromatic H), 6.99 (d, 12H, aromatic H), 6.98 (m, 2H, 2 × CHCHCO2), 5.77 (d, 2H, 2 × CHCHCO2, 3Jtrans = 15.51 Hz), 4.71 (m, 4H, 2 × CH CHCO2CH2CH2), 4.47 (m, 12H, 2 × CHCHCO2CH2, 2 × O2CC(C60)CO2CH2 and 2 × O2CC(C60)CO2CH2CH2), 4.34 (t, 8H, 4 × ArCO2CH2), 4.04 (m, 12H, 6 × CH2OAr), 2.14 (m, 4H, 2 × CH2CHCH), 1.84−1.75 (m, 28H, 6 × CH2CH2OAr, 6 × CO2CH2CH2 and 2 × CH2CH2CHCH), 1.45−1.26 (m, 96H, aliphatic H). 13C NMR (δ in ppm, 100 MHz, CD2Cl2): 166.5, 165.5, 165.2, 165.0, 164.5, 164.3, 164.01, 163.99, 163.8, 152.2, 151.7, 151.2, 146.12, 146.04, 145.9, 145.8, 145.69, 145.67, 145.65, 145.4, 145.35, 145.20, 145.17, 145.11, 145.08, 145.06, 144.4, 144.35, 143.59, 143.56, 143.52, 143.50, 143.48, 143.4, 142.71, 142.69, 142.45, 142.40, 142.37, 141.4, 139.7, 139.5, 139.4, 137.2, 133.2, 133.0, 132.9, 132.7, 128.8, 128.2, 128.1, 127.7, 123.1, 121.8, 121.3, 120.9, 119.35, 115.0, 114.9, 111.6, 72.4, 72.2, 69.03, 68.99, 68.1, 68.0, 66.3, 65.5, 62.1, 53.3, 53.1, 32.9, 30.14, 30.1, 30.04, 30.00, 29.97, 29.88, 29.86, 29.80, 29.78, 29.7, 29.6, 29.2, 29.13, 29.08, 28.52, 28.46, 26.62, 26.60, 26.58, 26.56, 26.54, 26.52, 26.3. MS [MALDI(+)]: 5630.75 [M + Na]+. Anal. Calcd for C387H230N4O42 (5608.08): C, 82.89; H, 4.13; N, 1.00%. Found: C, 83.08; H, 4.22; N, 1.06%. UV−Vis [λmax in nm (ε in l mol−1 cm−1), CH2Cl2]: 426 (8839), 488 (4686), 688 (532). Compound 2. This compound was obtained from 10 (0.35 g, 1.56 × 10−1 mmol), 13 (0.27 × 10−1 g, 6.52 × 10−2 mmol), secondgeneration Grubbs catalyst (0.55 × 10−2 g, 6.52 × 10−3 mmol), and CuI (0.37 × 10−3 g, 1.95 × 10−3 mmol) in CH2Cl2 (10 mL). Yield: 37% (1.18 × 10−1 g, 2.41 × 10−2 mmol). 1H NMR (δ in ppm, 400 MHz, CD2Cl2): 8.55 (br s, 2H, aromatic H), 8.13 (d, 12H, aromatic H), 8.04 (br s, 4H, aromatic H), 7.75 (d, 8H, aromatic H), 7.72 (d, 8H, aromatic H), 7.67 (d, 8H, aromatic H), 7.32 (d, 8H, aromatic H), 6.95 (m, 14H, aromatic H and 2 × CHCHCO2), 5.78 (d, 2H, 2 × CHCHCO2, 3Jtrans = 15.64 Hz), 4.71 (m, 4H, 2 × CH CHCO2CH2CH2), 4.48 (m, 8H, 2 × CHCHCO2CH2 and O2CC(C60)CO2CH2CH2), 4.34 (t, 8H, 4 × ArCO2CH2), 4.08 (t, 4H, 2 × O2CCH2CO2CH2), 4.04 (t, 12H, 6 × CH2OAr), 3.32 (s, 2H, O2CCH2CO2), 2.17 (q, 4H, 2 × CH2CHCH), 1.81−1.75 (m, 24H, 3216


Article

The Journal of Organic Chemistry Compound 5. This compound was obtained from 12 (0.19 g, 5.37 × 10−2 mmol), 14 (0.25 × 10−1 g, 2.24 × 10−2 mmol), secondgeneration Hoveyda−Grubbs catalyst (0.14 × 10−2 g, 2.24 × 10−3 mmol), and CuI (0.13 × 10−3 g, 6.72 × 10−4 mmol) in CH2Cl2 (8 mL). Yield: 27% (4.90 × 10−2 g, 6.06 × 10−3 mmol). 1H NMR (δ in ppm, 400 MHz, CD2Cl2): 8.92 (br s, 2H, aromatic H), 8.56 (br s, 4H, aromatic H), 8.35 (br s, 4H, aromatic H), 8.15 (d, 4H, aromatic H), 8.12 (m, 24H, aromatic H), 7.74 (d, 16H, aromatic H), 7.71 (d, 16H, aromatic H), 7.66 (d, 16H, aromatic H), 7.31 (d, 16H, aromatic H), 6.98 (m, 22H, aromatic H and 2 × CHCHCO2), 5.84 (d, 2H, 2 × CHCHCO2, 3Jtrans = 15.26 Hz), 4.70 (m, 4H, 2 × CH CHCO2CH2CH2), 4.47 (m, 12H, 2 × CHCHCO2CH2, 2 × O2CC(C60)CO2CH2, and 2 × O2CC(C60)CO2CH2CH2), 4.34 (t, 16H, 8 × ArCO2CH2), 4.03 (t, 20H, 10 × CH2OAr), 2.14 (m, 4H, 2 × CH 2 CHCH), 1.79 (m, 44H, 10 × CH 2 CH 2 OAr, 10 × ArCO2CH2CH2 and 2 × O2CCH2CH2CH2), 1.54−1.39 (m, 144H, aliphatic H). 13C NMR (δ in ppm, 100 MHz, CD2Cl2): 167.7, 166.5, 165.3, 165.2, 164.9, 164.65, 164.3, 164.00, 163.97, 163.7, 153.2, 152.3, 152.2, 151.20, 151.15, 146.10, 146.08, 146.0, 145.9, 145.7, 145.6, 145.35, 145.32, 145.29, 145.19, 145.15, 145.08, 145.06, 145.0, 144.3, 143.6, 143.55, 143.49, 143.47, 143.4, 142.7, 142.5, 142.42, 142.38, 142.35, 141.4, 139.6, 139.51, 139.50, 139.48, 139.46, 139.42, 139.40, 139.37, 137.2, 133.3, 133.2, 133.0, 132.7, 131.7, 129.5, 129.4, 128.8, 128.6, 128.2, 127.4, 123.1, 121.8, 120.9, 119.35, 115.0, 114.9, 111.55, 72.4, 72.2, 69.1, 69.0, 68.1, 68.0, 66.4, 65.5, 65.4, 53.3, 53.2, 32.9, 32.5, 30.25, 30.21, 30.16, 30.12, 30.08, 30.03, 30.00, 29.94, 29.92, 29.88, 29.8, 29.7, 29.6, 29.2, 29.1, 28.5, 26.60, 26.58, 26.54, 26.52, 26.49, 23.25. MS [MALDI(+)]: 8101.50 [M + Na]+. Anal. Calcd for C539H370N8O70 (8078.86): C, 80.13; H, 4.62; N, 1.39%. Found: C, 80.11; H, 4.50; N, 1.50%. UV−Vis [λmax in nm (ε in l mol−1 cm−1), CH2Cl2]: 426 (11748), 486 (6897), 690 (811). Compound 6. This compound was obtained from 12 (0.17 g, 4.96 × 10−2 mmol), 13 (0.85 × 10−2 g, 2.07 × 10−2 mmol), secondgeneration Hoveyda−Grubbs catalyst (0.13 × 10−2 g, 2.07 × 10−3 mmol), and CuI (0.12 × 10−3 g, 6.21 × 10−4 mmol) in CH2Cl2 (8 mL). Yield: 21% (3.20 × 10−2 g, 4.35 × 10−3 mmol). 1H NMR (δ in ppm, 400 MHz, CD2Cl2): 8.92 (br s, 2H, aromatic H), 8.59 (br s, 4H, aromatic H), 8.36 (br s, 4H, aromatic H), 8.16 (d, 4H, aromatic H), 8.12 (m, 24H, aromatic H), 7.75 (d, 16H, aromatic H), 7.71 (d, 16H, aromatic H), 7.66 (d, 16H, aromatic H), 7.32 (d, 16H, aromatic H), 6.98 (m, 22H, aromatic H and 2 × CHCHCO2), 5.82 (d, 2H, 2 × CHCHCO2, 3Jtrans = 15.84 Hz), 4.71 (m, 4H, 2 × CH CHCO2CH2CH2), 4.48 (m, 8H, 2 × CHCHCO2CH2 and 2 × O2CC(C60)CO2CH2CH2), 4.36 (t, 16H, 8 × ArCO2CH2), 4.08 (t, 4H, 2 × O2CCH2CO2CH2) 4.03 (t, 20H, 10 × CH2OAr), 3.32 (s, 2H, O2CCH2CO2), 2.18 (q, 4H, 2 × CH2CHCH), 1.81 (m, 44H, 10 × CH2CH2OAr, 10 × ArCO2CH2CH2 and 2 × O2CCH2CH2CH2), 1.62−1.27 (m, 144H, aliphatic H). 13C NMR (δ in ppm, 100 MHz, CD2Cl2): 167.2, 166.6, 165.3, 165.2, 164.9, 164.7, 164.3, 164.0, 163.85, 163.71, 163.69, 152.3, 152.2, 151.24, 151.16, 146.00, 145.99, 145.8, 145.7, 145.4, 145.23, 145.17, 145.11, 145.08, 144.40, 144.35, 143.9, 143.59, 143.56, 143.51, 143.48, 143.47, 142.7, 142.45, 142.4, 141.5, 139.6, 139.5, 137.2, 133.3, 133.2, 133.0, 132.7, 131.8, 129.5, 129.4, 128.8, 128.6, 128.2, 127.4, 123.1, 121.8, 120.9, 119.35, 115.1, 114.9, 111.6, 72.2, 69.1, 69.0, 68.1, 66.4, 66.1, 65.5, 62.1, 53.1, 42.2, 32.9, 30.11, 30.07, 30.04, 30.01, 29.95, 29.90, 29.8, 29.75, 29.7, 29.62, 29.59, 29.3, 29.2, 29.14, 29.07, 29.0, 28.6, 26.59, 26.54, 26.50, 26.48, 26.4. MS [MALDI(+)]: 7382.55 [M + Na]+. Anal. Calcd for C479H372N8O70 (7364.30): C, 78.12; H, 5.15; N, 1.52%. Found: C, 78.04; H, 4.86; N, 1.49%. UV−Vis [λmax in nm (ε in l mol−1 cm−1), CH2Cl2]: 426 (5515), 488 (3676), 686 (367). Compound 7. This compound was obtained from 11 (0.25 g, 9.24 × 10−2 mmol), 14 (0.43 × 10−1 g, 3.85 × 10−2 mmol), secondgeneration Hoveyda−Grubbs catalyst (0.24 × 10−2 g, 3.85 × 10−3 mmol), and CuI (0.22 × 10−3 g, 1.15 × 10−3 mmol) in CH2Cl2 (8 mL). Yield: 25% (6.39 × 10−2 g, 9.63 × 10−3 mmol). 1H NMR (δ in ppm, 400 MHz, CD2Cl2): 8.92 (br s, 2H, aromatic H), 8.59 (br s, 4H, aromatic H), 8.35 (br s, 4H, aromatic H), 8.16 (d, 4H, aromatic H), 8.12 (m, 24H, aromatic H), 7.75 (d, 16H, aromatic H), 7.71 (d, 16H, aromatic H), 7.66 (d, 16H, aromatic H), 7.32 (d, 16H, aromatic H),

6.99 (m, 22H, aromatic H and 2 × CHCHCO2), 5.81 (d, 2H, 2 × CHCHCO 2 , 3 J t r a n s = 15.56 Hz), 4.47 (t, 4H, 2 × O2CCH2CO2CH2CH2), 4.34 (m, 20H, 2 × CHCHCO2CH2 and 8 × ArCO2CH2), 4.30 (m, 4H, 2 × CHCHCO2CH2CH2), 4.10 (t, 4H, 2 × O2CC(C60)CO2CH2), 4.06 (t, 20H, 10 × CH2OAr), 3.38 (s, 4H, 2 × O2CCH2CO2), 2.22 (q, 4H, 2 × CH2CHCH), 1.81 (m, 44H, 10 × CH 2 CH 2 OAr, 10 × ArCO 2 CH 2 CH 2 and 2 × O2CCH2CH2CH2), 1.62−1.27 (m, 144H, aliphatic H). 13C NMR (δ in ppm, 100 MHz, CD2Cl2): 167.0, 166.9, 166.6, 166.55, 165.3, 165.2, 164.9, 164.69, 164.3, 164.0, 163.7, 152.3, 152.2, 151.2, 151.0, 146.1, 145.75, 145.7, 145.35, 145.22, 145.18, 145.1, 144.4, 143.6, 143.51, 143.48, 142.7, 142.4, 141.45, 139.54, 139.49, 137.2, 133.3, 133.2, 133.0, 132.7, 131.75, 129.5, 129.35, 128.8, 128.6, 128.2, 127.4, 123.1, 121.8, 121.0, 119.35, 115.1, 114.9, 111.6, 72.4, 69.1, 69.0, 68.0, 66.4, 63.75, 62.2, 58.3, 42.0, 32.8, 30.07, 30.03, 30.00, 29.93, 29.90, 29.88, 29.80, 29.78, 29.77, 29.75, 29.7, 29.64, 29.62, 29.19, 29.16, 29.0, 28.6, 26.6, 26.55, 26.53, 26.50, 26.48, 26.4, 26.3. MS [MALDI(+)]: 6663.60 [M + Na]+. Anal. Calcd for C419H374N8O70 (6641.58): C, 75.77; H, 5.68; N, 1.69%. Found: C, 75.87; H, 5.54; N, 1.73%. UV−Vis [λmax in nm (ε in l mol−1 cm−1), CH2Cl2]: 426 (2428), 488 (1456), 686 (162). Compound 8. This compound was obtained from 11 (0.24 g, 8.71 × 10−2 mmol), 13 (0.15 × 10−1 g, 3.63 × 10−2 mmol), secondgeneration Hoveyda−Grubbs catalyst (0.23 × 10−2 g, 3.63 × 10−3 mmol), and CuI (0.21 × 10−3 g, 1.08 × 10−3 mmol) in CH2Cl2 (8 mL). Yield: 20% (4.30 × 10−2 g, 7.26 × 10−3 mmol). 1H NMR (δ in ppm, 400 MHz, CD2Cl2): 8.92 (t, 2H, aromatic H), 8.59 (t, 4H, aromatic H), 8.35 (d, 4H, aromatic H), 8.16 (d, 4H, aromatic H), 8.11 (m, 24H, aromatic H), 7.75 (d, 16H, aromatic H), 7.71 (d, 16H, aromatic H), 7.66 (d, 16H, aromatic H), 7.31 (d, 16H, aromatic H), 6.99 (m, 22H, aromatic H and 2 × CHCHCO2), 5.81 (dt, 2H, 2 × CHCHCO2, 3Jtrans = 15.57 Hz, 4J = 1.41 Hz), 4.71 (m, 20H, 2 × CHCHCO2CH2 and 8 × ArCO2CH2), 4.30 (m, 4H, 2 × CH CHCO2CH2CH2), 4.10 (t, 4H, 2 × O2CCH2CO2CH2), 4.09 (t, 4H, 2 × O2CCH2CO2CH2CH2), 4.02 (t, 20H, 10 × CH2OAr), 3.38 (s, 4H, 2 × O2CCH2CO2), 3.33 (s, 2H, O2CCH2CO2), 2.18 (q, 4H, 2 × CH 2 CHCH), 1.81 (m, 44H, 10 × CH 2 CH 2 OAr, 10 × ArCO2CH2CH2 and 2 × O2CCH2CH2CH2), 1.62−1.27 (m, 144H, aliphatic H). 13C NMR (δ in ppm, 100 MHz, CD2Cl2): 167.2, 167.0, 166.9, 166.6, 165.3, 165.2, 164.9, 164.7, 164.3, 163.7, 162.9, 152.3, 152.2, 151.25, 151.0, 145.2, 137.2, 133.3, 133.2, 133.0, 132.7, 131.8, 129.5, 129.3, 128.8, 128.6, 128.2, 127.4, 123.1, 121.8, 121.0, 119.4, 115.1, 114.9, 111.6, 69.1, 69.0, 66.4, 66.2, 66.1, 63.75, 62.2, 42.2, 42.0, 32.8, 30.03, 30.00, 29.96, 29.93, 29.9, 29.85, 29.80, 29.76, 29.78, 29.72, 29.66, 29.65, 29.59, 29.58, 29.5, 29.2, 29.05, 29.0, 28.6, 26.54, 26.50, 26.49, 26.3. MS [MALDI(+)]: 5945.69 [M + Na]+. Anal. Calcd for C359H376N8O70 (5922.93): C, 72.80; H, 6.40; N, 1.89%. Found: C, 72.55; H, 6.36; N, 1.92%.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.joc.8b00093. Copies of 1H and 13C NMR spectra for all new compounds and liquid-crystalline properties such as DSC thermograms, POM photomicrographs, and SAXS patterns (PDF)

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. ORCID

Bertrand Donnio: 0000-0001-5907-7705 Robert Deschenaux: 0000-0002-1142-0022 Notes

The authors declare no competing financial interest. 3217


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(b) Plant, S. R.; Jevric, M.; Morton, J. J. L.; Ardavan, A.; Khlobystov, A. N.; Briggs, G. A. D.; Porfyrakis, K. Chem. Sci. 2013, 4, 2971−2975. (c) Abe, Y.; Tanaka, H.; Guo, Y.; Matsuo, Y.; Nakamura, E. J. Am. Chem. Soc. 2014, 136, 3366−3369. (d) Moreno-García, P.; La Rosa, A.; Kolivoška, V.; Bermejo, D.; Hong, W.; Yoshida, K.; Baghernejad, M.; Filippone, S.; Broekmann, P.; Wandlowski, T.; Martín, N. J. Am. Chem. Soc. 2015, 137, 2318−2327. (e) Wolf, M.; Villegas, C.; Trukhina, O.; Delgado, J. L.; Torres, T.; Martín, N.; Clark, T.; Guldi, D. M. J. Am. Chem. Soc. 2017, 139, 17474−17483. (14) (a) Prato, M. J. Mater. Chem. 1997, 7, 1097−1109. (b) Miller, G. P.; Briggs, J. Org. Lett. 2003, 5, 4203−4206. (15) (a) Atienza, C. M.; Fernández, G.; Sánchez, L.; Martín, N.; Sá Dantas, I.; Wienk, M. M.; Janssen, R. A. J.; Aminur Rahman, G. M.; Guldi, D. M. Chem. Commun. 2006, 514−516. (b) Fernández, G.; Sánchez, L.; Veldman, D.; Wienk, M. M.; Atienza, C.; Guldi, D. M.; Janssen, R. A. J.; Martín, N. J. Org. Chem. 2008, 73, 3189−3196. (16) (a) Hosomizu, K.; Imahori, H.; Hahn, U.; Nierengarten, J.-F.; Listorti, A.; Armaroli, N.; Nemoto, T.; Isoda, S. J. Phys. Chem. C 2007, 111, 2777−2786. (b) Fernández, G.; Pérez, E. M.; Sánchez, L.; Martín, N. Angew. Chem., Int. Ed. 2008, 47, 1094−1097. (c) Hahn, U.; Nierengarten, J.-F.; Vögtle, F.; Listorti, A.; Monti, F.; Armaroli, N. New J. Chem. 2009, 33, 337−344. (d) Kim, J.; Yun, M. H.; Lee, J.; Kim, J. Y.; Wudl, F.; Yang, C. Chem. Commun. 2011, 47, 3078−3080. (e) Cao, R., Jr.; Isla, H.; Cao, R.; Pérez, E. M.; Martín, N. Chem. Sci. 2011, 2, 1384−1388. (f) Hörmann, F.; Hirsch, A. Chem. - Eur. J. 2013, 19, 3188−3197. (g) Isla, H.; Pérez, E. M.; Martín, N. Angew. Chem., Int. Ed. 2014, 53, 5629−5633. (17) Wang, C. L.; Zhang, W. B.; Hsu, C.-H.; Sun, H.-J.; Van Horn, R. M.; Tu, Y.; Anokhin, D. V.; Ivanov, D. A.; Cheng, S. Z. D. Soft Matter 2011, 7, 6135−6143. (18) (a) Donnio, B.; Buathong, S.; Bury, I.; Guillon, D. Chem. Soc. Rev. 2007, 36, 1495−1513. (b) Rosen, B. M.; Wilson, C. J.; Wilson, D. A.; Peterca, M.; Imam, M. R.; Percec, V. Chem. Rev. 2009, 109, 6275− 6540. (19) Russo, V.; Pieper, P.; Heinrich, B.; Donnio, B.; Deschenaux, R. Chem. - Eur. J. 2016, 22, 17366−17376. (20) (a) Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18− 29. (b) Sanford, M. S.; Love, J. A.; Grubbs, R. H. J. Am. Chem. Soc. 2001, 123, 6543−6554. (c) Chatterjee, A. K.; Choi, T.-L.; Sanders, D. P.; Grubbs, R. H. J. Am. Chem. Soc. 2003, 125, 11360−11370. (d) Ornelas, C.; Méry, D.; Cloutet, E.; Aranzaes, J. R.; Astruc, D. J. Am. Chem. Soc. 2008, 130, 1495−1506. (e) Trinh, T. M. N.; Nguyen, T. T.; Kopp, C.; Pieper, P.; Russo, V.; Heinrich, B.; Donnio, B.; Nguyen, T. L. A.; Deschenaux, R. Eur. J. Org. Chem. 2015, 2015, 6005−6010. (21) (a) Bingel, C. Chem. Ber. 1993, 126, 1957−1959. (b) Bourgeois, J.-P.; Diederich, F.; Echegoyen, L.; Nierengarten, J.-F. Helv. Chim. Acta 1998, 81, 1835−1844. (c) Nierengarten, J.-F.; Gramlich, V.; Cardullo, F.; Diederich, F. Angew. Chem., Int. Ed. Engl. 1996, 35, 2101−2103. (22) Voigtritter, K.; Ghorai, S.; Lipshutz, B. H. J. Org. Chem. 2011, 76, 4697−4702. (23) (a) Nguyen, S. T.; Grubbs, R. H.; Ziller, J. W. J. Am. Chem. Soc. 1993, 115, 9858−9859. (b) Schwab, P.; Grubbs, R. H.; Ziller, J. W. J. Am. Chem. Soc. 1996, 118, 100−110. (c) Weskamp, T.; Kohl, F. J.; Hieringer, W.; Gleich, D.; Herrmann, W. A. Angew. Chem., Int. Ed. 1999, 38, 2416−2419. (d) Scholl, M.; Trnka, T. M.; Morgan, J. P.; Grubbs, R. H. Tetrahedron Lett. 1999, 40, 2247−2250. (e) Huang, J.; Stevens, E. D.; Nolan, S. P.; Petersen, J. L. J. Am. Chem. Soc. 1999, 121, 2674−2678. (f) Huang, J.; Schanz, H.-J.; Stevens, E. D.; Nolan, S. P. Organometallics 1999, 18, 5375−5380. (g) Grubbs, R. H. Angew. Chem., Int. Ed. 2006, 45, 3760−3765. (24) (a) Garber, B. S.; Kingsbury, J. S.; Gray, B. L.; Hoveyda, A. H. J. Am. Chem. Soc. 2000, 122, 8168−8179. (b) Hoveyda, A. H.; Zhugralin, A. R. Nature 2007, 450, 243−251. (c) Samojtowicz, C.; Bieniek, M.; Grela, K. Chem. Rev. 2009, 109, 3708−3742. (d) Ashworth, I. W.; Hillier, I. H.; Nelson, D. J.; Percy, J. M.; Vincent, M. A. ACS Catal. 2013, 3, 1929−1939. (e) Nelson, D. J.; Manzini, S.; Urbina-Blanco, C. A.; Nolan, S. P. Chem. Commun. 2014, 50, 10355−10375. (25) (a) Cardullo, F.; Seiler, P.; Isaacs, L.; Nierengarten, J. F.; Haldimann, R. F.; Diederich, F.; Mordasini-Denti, T.; Thiel, W.;

ACKNOWLEDGMENTS R.D. thanks the Swiss National Science Fountation (grant no. 200021-165715) for financial support. B.D. and B.H. thank the CNRS and the University of Strasbourg. We acknowledge SOLEIL for the provision of the synchrotron radiation facilities and the team of Dr. Javier Perez and, particularly, Dr. Thomas Bizien for adjustments and for assistance in using beamline SWING. We thank Pohang Accelerator Laboratory (PAL) for giving us the opportunity to perform GIWAXS measurements, MEST and POSTECH for supporting these experiments, and Dr. Hyungju for adjustments and help. This research was supported by the Leading Foreign Research Institute Recruitment Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2010-00453).

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REFERENCES

(1) Echegoyen, L.; Echegoyen, L. E. Acc. Chem. Res. 1998, 31, 593− 601. (2) Guldi, D. M.; Illescas, B. M.; Atienza, C. M.; Wielopolski, M.; Martín, N. Chem. Soc. Rev. 2009, 38, 1587−1597. (3) (a) Kato, T.; Mizoshita, N.; Kishimoto, K. Angew. Chem., Int. Ed. 2006, 45, 38−68. (b) Tschierske, C. Chem. Soc. Rev. 2007, 36, 1930− 1970. (c) Goodby, J. W.; Saez, I. M.; Cowling, S. J.; Görtz, V.; Draper, M.; Hall, A. W.; Sia, S.; Cosquer, G.; Lee, S. E.; Raynes, E. P. Angew. Chem., Int. Ed. 2008, 47, 2754−2787. (4) Lehmann, M.; Hügel, M. Angew. Chem., Int. Ed. 2015, 54, 4110− 4114. (5) Vergara, J.; Barberá, J.; Serrano, J. L.; Ros, M. B.; Sebastián, N.; de La Fuente, R.; López, D. O.; Fernández, G.; Sánchez, L.; Martín, N. Angew. Chem., Int. Ed. 2011, 50, 12523−12528. (6) Li, W.-S.; Yamamoto, Y.; Fukushima, T.; Saeki, A.; Seki, S.; Tagawa, S.; Masunaga, H.; Sasaki, S.; Takata, M.; Aida, T. J. Am. Chem. Soc. 2008, 130, 8886−8887. (7) (a) Fernandes, P. A. L.; Yagai, S.; Möhwald, H.; Nakanishi, T. Langmuir 2010, 26, 4339−4345. (b) Li, H.; Babu, S. S.; Turner, S. T.; Neher, D.; Hollamby, M. J.; Seki, T.; Yagai, S.; Deguchi, Y.; Möhwald, H.; Nakanishi, T. J. Mater. Chem. C 2013, 1, 1943−1951. (c) Ghosh, A.; Nakanishi, T. Chem. Commun. 2017, 53, 10344−10357. (d) Zhu, T.; Zhang, X.; Li, Z.; Hsu, C.-H.; Chen, W.; Miyoshi, T.; Li, X.; Yang, X.; Tu, Y.; Li, C. Y. Chem. Commun. 2017, 53, 8336−8339. (8) (a) Sawamura, M.; Kawai, K.; Matsuo, Y.; Kanie, K.; Kato, T.; Nakamura, E. Nature 2002, 419, 702−705. (b) Lenoble, J.; Campidelli, S.; Maringa, N.; Donnio, B.; Guillon, D.; Yevlampieva, N.; Deschenaux, R. J. Am. Chem. Soc. 2007, 129, 9941−9952. (c) Hayashi, H.; Nihashi, W.; Umeyama, T.; Matano, Y.; Seki, S.; Shimizu, Y.; Imahori, H. J. Am. Chem. Soc. 2011, 133, 10736−10739. (9) Felder-Flesch, D.; Rupnicki, L.; Bourgogne, C.; Donnio, B.; Guillon, D. J. Mater. Chem. 2006, 16, 304−309. (10) (a) Torres, T.; Gouloumis, A.; Sanchez-Garcia, D.; Jayawickramarajah, J.; Seitz, W.; Guldi, D. M.; Sessler, J. L. Chem. Commun. 2007, 292−294. (b) Figueira-Duarte, T. M.; Gégout, A.; Nierengarten, J.-F. Chem. Commun. 2007, 109−119. (c) Hizume, Y.; Tashiro, K.; Charvet, R.; Yamamoto, Y.; Saeki, A.; Seki, S.; Aida, T. J. Am. Chem. Soc. 2010, 132, 6628−6629. (d) Pelado, B.; Abou-Chahine, F.; Calbo, J.; Caballero, R.; de la Cruz, P.; Junquera-Hernández, J. M.; Ortí, E.; Tkachenko, N. V.; Langa, F. Chem. - Eur. J. 2015, 21, 5814− 5825. (11) (a) de la Torre, G.; Giacalone, F.; Segura, J. L.; Martín, N.; Guldi, D. M. Chem. - Eur. J. 2005, 11, 1267−1280. (b) Fukuzumi, S.; Ohkubo, K. Dalton Trans. 2013, 42, 15846−15858. (12) (a) Li, Y. Acc. Chem. Res. 2012, 45, 723−733. (b) Liu, Y.; Zhao, J.; Li, Z.; Mu, C.; Ma, W.; Hu, H.; Jiang, K.; Lin, H.; Ade, H.; Yan, H. Nat. Commun. 2014, 5, 5293. (c) Lin, Y.; Wang, J.; Zhang, Z.-G.; Bai, H.; Li, Y.; Zhu, D.; Zhan, X. Adv. Mater. 2015, 27, 1170−1174. (13) (a) Lee, K.; Choi, Y. J.; Cho, Y.-J.; Lee, C. Y.; Song, H.; Lee, C. H.; Lee, Y. S.; Park, J. T. J. Am. Chem. Soc. 2004, 126, 9837−9844. 3218


Article

The Journal of Organic Chemistry Boudon, C.; Gisselbrecht, J. P.; Gross, M. Helv. Chim. Acta 1997, 80, 343−371. (b) Ma, B.; Bunker, C. E.; Guduru, R.; Zhang, X.-F.; Sun, Y.P. J. J. Phys. Chem. A 1997, 101, 5626−5632. (c) Guldi, D. M. Chem. Commun. 2000, 321−327. (26) Deschenaux, R.; Donnio, B.; Guillon, D. New J. Chem. 2007, 31, 1064−1073. (27) Nagy, Z. T.; Heinrich, B.; Guillon, D.; Tomczyk, J.; Stumpe, J.; Donnio, B. J. Mater. Chem. 2012, 22, 18614−18622. (28) Kitamoto, T.; Sasaki, S.; Atake, T.; Tanaka, T.; Kawaji, H.; Kikuchi, K.; Saito, K.; Suzuki, S.; Achiba, Y.; Ikemoto, I. Jpn. J. Appl. Phys. 1993, 32, L424−427. (29) (a) Guillon, D.; Skoulios, A. Mol. Cryst. Liq. Cryst. 1983, 91, 341−352. (b) Guillon, D.; Skoulios, A. J. Phys. (Paris) 1984, 45, 607− 621.

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