Article pubs.acs.org/joc
Induced-Dipole-Directed, Cooperative Self-Assembly of a Benzotrithiophene Toshiaki Ikeda,† Hiroaki Adachi,† Hiroyuki Fueno,‡ Kazuyoshi Tanaka,§ and Takeharu Haino*,† †
Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan ‡ Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan § Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Nishihiraki-cho, Takano, Sakyo-ku, Kyoto 606-8103, Japan S Supporting Information *
ABSTRACT: A benzotrithiophene derivative possessing phenylisoxazoles self-assembled to form stacks. The molecule isodesmically self-assembled in chloroform, whereas it self-assembled in a cooperative fashion in decalin and in methylcyclohexane. Thermodynamic studies based on isodesmic, van der Schoot, and Goldstein−Stryer mathematical models revealed that the self-assembly processes are enthalpically driven and entropically opposed. An enthalpy−entropy compensation plot indicates that the assembly processes in chloroform, decalin, and methylcyclohexane are closely related. The enthalpic gains in less-polar solvents are greater than those in more-polar solvents, resulting in the formation of large assemblies in decalin and in methylcyclohexane. The formation of large assemblies leads to cooperative assemblies. The elongation process is enthalpically more favored than the nucleation process, which drives the cooperativity of the self-assembly. DFT calculations suggested that a hexameric assembly is more stable than tetrameric or dimeric assemblies. Cooperative self-assemblies based on intermolecular interactions other than hydrogen bonding have rarely been reported. It is demonstrated herein that van der Waals interactions, including induced dipole−dipole interactions, can drive the cooperative assembly of planar π-conjugated molecules.
■
INTRODUCTION Supramolecular polymers have attracted a great deal of interest owing to their advantageous properties, including their responsiveness to stimuli, ability to self-heal, and photo- and electrochemical properties.1 A serious challenge in the field of supramolecular polymers is the ability to regulate polydispersity.2 The step-growth polymerization and reversible nature of a supramolecular polymer cause particular difficulty in the regulation of polydispersity. Living supramolecular polymerization that provides supramolecular polymers with a low polydispersity index is a proposed solution to the problem.3 A key to achieving supramolecular living polymerization is cooperative self-assembly that involves two assembly regimes with distinct association constants (i.e., an initial nucleation regime with Kn and succeeding elongation regime with Ke).2a,4 Positive cooperativity occurs when the elongation process is more favorable, that is, Ke ≫ Kn. Recent theoretical investigations into cooperative assembly predicted that assembly-induced dipole−dipole interactions determine the cooperativity of the self-assembly; the dipoles of monomers are induced by the formation of assemblies, which facilitates stronger dipole−dipole interactions of the assemblies.5 Most of the cooperative assemblies have been observed on supramolecular polymers assembled through head-to-tail hydrogen-bonding interactions of amide moieties.6 The one© 2017 American Chemical Society
dimensional hydrogen-bonding array of the amide moiety induces polarization of the amide dipole, resulting in cooperativity. Cooperative assembly based on interactions other than hydrogen bonding has rarely been reported.7 Our group has reported a cooperatively assembling carbazole derivative possessing phenylisoxazole moieties.8 The linear array of the dipole moments of the isoxazole rings in the assembly induced further polarization of the dipole, resulting in the cooperative assembly, whereas other π-conjugated molecules possessing phenylisoxazoles did not exhibit cooperativity in their assemblies.9 Then, we envisioned the use of van der Waals interactions, including induced dipole−induced dipole interactions, as the driving force of the cooperative assembly. We employed a benzotrithiophene moiety as the core.10 Sulfur atoms in the benzotrithiophenes are highly polarizable, which allows strong van der Waals interactions; these are commonly known as sulfur−sulfur interactions.11 In this paper, the selfassembling behavior of a benzotrithiophene derivative that possesses phenylisoxazoles (1) is reported (Scheme 1). Compound 1 isodesmically self-assembled in chloroform, whereas cooperativity in the self-assembly of 1 was observed in decalin and in methylcyclohexane (MCH). Theoretical Received: June 20, 2017 Published: September 1, 2017 10062
DOI: 10.1021/acs.joc.7b01520 J. Org. Chem. 2017, 82, 10062−10069
Article
The Journal of Organic Chemistry Scheme 1. Molecular Structures and the Cooperative SelfAssembly of 1
calculations suggested that the bending of the flat benzotrithiophene in the assembly induced a dipole, which allows cooperativity in the assembly of 1.
■
RESULTS AND DISCUSSION Synthesis. The chemical reaction to synthesize 1 is summarized in Scheme 2. The 1,3-dipolar addition of triethynylbenzotrithiophene (3)7a,12 to 4-decyloxyphenylchlorooxime (4)9f in dichloromethane provided target compound 1 in 48% yield. Scheme 2. Synthesis of Tris(phenylisoxazolyl)benzotrithiophene (1)
Figure 1. (a) 1H NMR spectra of 1 at various concentrations in chloroform-d at 25 °C. The concentrations are (from top to bottom) 30.0, 20.0, 15.0, 5.0, and 2.0 mmol L−1. (b) Nonlinear curve fitting of the self-assembly of 1 using 1H NMR in chloroform-d1 at 298 K. The lines display fitting curves based on the isodesmic model. (c) A van’t Hoff plot based on the analysis of 1H NMR spectra at various temperatures.
Self-Assembly in Organic Media. The self-assembly of 1 was investigated by using 1 H NMR spectroscopy. A concentration dependency was observed in the 1H NMR spectra of 1 in chloroform-d (Figure 1). Upfield shifts of aromatic protons were observed with increasing the concentration from 0.5 to 30.0 mmol L−1, suggesting the formation of stacked assemblies in which the ring current of the neighboring molecules shields the aromatic protons of 1. Complexationinduced shifts (Δδ = −1.59, −1.15, −0.88, and −0.67 ppm for Ha, Hb, Hc, and Hd, respectively) and an association constant (Ki) of 1.8(1) × 102 L mol−1 were estimated by using nonlinear curve-fitting analysis based on an isodesmic model4c with a high probability (χ2) of 0.999 (Figure 1b). Thus, 1 isodesmically self-assembled in chloroform-d at 25 °C. The complexationinduced shift was largest for Ha and gradually decreased as the distance from the C3 axis of the central benzotrithiophene increases, indicating that 1 stacked as piles along the C3 axis. The enthalpic and entropic contributions (ΔH and ΔS) for the association were determined to be −4.20(6) kcal mol−1 and −3.7(2) cal mol−1 K−1, respectively, from a van’t Hoff plot (Figure 1c). This finding suggests that the self-assembly is enthalpically driven and entropically opposed. UV−vis absorption spectroscopy in a variety of solvents provided more insight into the self-assembly of 1. Compound 1 exhibited an absorption band at 330 nm resulting from monomeric 1 in chloroform and in toluene, indicating that most of 1 still exists as a monomer under these conditions
[Figure S1, Supporting Information (SI)]. It is known that lesspolar solvents facilitate the assembly of π-conjugated molecules possessing phenylisoxazoles.8,9e−g Thus, decalin and MCH were employed as less-polar solvents. The UV−vis absorption spectra of 1 ([1] = 1.5 × 10−5 mol L−1) in decalin were temperature-dependent. Compound 1 displayed a monomeric absorption band (330 nm) at 50 °C. The intensity of the absorption band decreased and red-shifted bands appeared as the temperature decreased (Figure 2), suggesting the formation of J-aggregates. The absorption spectra steeply changed at about 35 °C. A nonsigmoidal melting curve that is characteristic of cooperative self-assembly was obtained by plotting the degree of aggregation (αagg) at 330 nm vs temperature (Figure 2f).4b The analysis based on van der Schoot’s mathematical model provides thermodynamic insight into the elongation regime of cooperative assembly.4c The curve-fitting of the cooling curve of αagg at 330 nm ([1] = 1.5 × 10−5 mol L−1) provides an elongation temperature (Te) of 306.5(2) K, resulting in an association constant in the elongation process at the elongation temperature [Ke(Te)] of 6.7 × 104 L mol−1. The enthalpic gain in the elongation process (ΔHe) was −18(1) kcal mol−1, which suggests that the elongation is enthalpically driven. A high degree of cooperativity was confirmed by a dimensionless equilibrium constant between nucleation and elongation (Ka) of 6.5(6) × 10−4. The degree of polymerization at the elongation temperature [Nn(Te)] was determined to be 11.5, 10063
DOI: 10.1021/acs.joc.7b01520 J. Org. Chem. 2017, 82, 10062−10069
Article
The Journal of Organic Chemistry
Figure 2. (a−e) UV−vis absorption spectra of 1 in decalin at various temperatures. The arrows represent the change in the spectra with decreasing temperature from 50 to 15 °C in steps of 1 °C. The concentrations of 1 are (a) 1.0× 10−5 mol L−1, (b) 1.5× 10−5 mol L−1, (c) 2.0× 10−5 mol L−1, (d) 2.5× 10−5 mol L−1, and (e) 3.0 × 10−5 mol L−1. (f) Plot of the degree of aggregation (αagg) at 330 nm vs temperature at various concentrations of 1 in decalin. The concentrations are 1.0 × 10−5 mol L−1 (open square), 1.5 × 10−5 mol L−1 (open circle), 2.0 × 10−5 mol L−1 (filled square), 2.5 × 10−5 mol L−1 (filled circle), and 3.0 × 10−5 mol L−1 (cross). Curves show the fitting curves based on van der Schoot’s model. (g) A van’t Hoff plot based on part f.
Figure 3. Concentration-dependent UV−vis absorption spectra of 1 in decalin at (a) 19 °C, (b) 21 °C, (c) 25 °C, and (d) 27 °C. The concentrations of 1 are 2.0, 2.5, 4.2, 4.5, 6.3, 7.5, 10.5, 12.0, 13.0, 13.5, 15.0, 21.0, 25.0, 45.0, and 54.0 × 10−6 mol L−1. The arrows indicate the change in the spectra as the concentration increased. The plot of the degree of aggregation vs KeCT in decalin at (e) 19 °C, (f) 21 °C, (g) 25 °C, and (h) 27 °C. (i) A van’t Hoff plot of Ke. (j) A van’t Hoff plot of Kn.
10064
DOI: 10.1021/acs.joc.7b01520 J. Org. Chem. 2017, 82, 10062−10069
Article
The Journal of Organic Chemistry Table 1. Summary of the Thermodynamic Parameters of the Self-Assembly of 1 solvent
model
ΔHn or ΔHi (kcal mol−1)
ΔSn or ΔSi (cal mol−1 K−1)
chloroform decalin
isodesmic van der Schoot Goldstein−Stryer van der Schoot Goldstein−Stryer
−4.20 (6)
−3.7 (2)
−7.3 (2)
−7.3 (7)
−9.9 (7)
−14 (2)
MCH
ΔHe (kcal mol−1) −13.1 −12.6 −16.1 −14.7
(9) (9) (7) (5)
ΔSe (cal mol−1 K−1) −20 −18 −27 −22
(3) (3) (2) (2)
Figure 4. (a−e) UV−vis absorption spectra of 1 in MCH at various temperatures. The arrows represent the change in the spectra with decreasing temperature from 60 to 10 °C in steps of 1 °C. The concentrations of 1 are (a) 5.0 × 10−6 mol L−1, (b) 7.0 × 10−6 mol L−1, (c) 10.0 × 10−6 mol L−1, (d) 12.0 × 10−6 mol L−1, and (e) 15.0 × 10−6 mol L−1. (f) Plot of the degree of aggregation (αagg) at 330 nm vs temperature at various concentrations of 1 in MCH. The concentrations are 5.0 × 10−6 mol L−1 (open square), 7.5 × 10−6 mol L−1 (open circle), 10.0 × 10−6 mol L−1 (filled square), 12.5 × 10−6 mol L−1 (filled circle), and 15.0 × 10−6 mol L−1 (cross). Curves show the fitting curves based on van der Schoot’s model. (g) A van’t Hoff plot based on part f.
indicating the cooperative assembly of 1. The analysis using the Goldstein−Stryer mathematical model fits the data well (Figure 3g), providing a Kn of 5.5 × 103 L mol−1, Ke of 1.8 × 105 L mol−1, σ of 0.03, and s of 5. The σ value is far smaller than 1, suggesting strong cooperativity. To obtain thermodynamic insight into the assembly of 1, the concentration-dependent UV−vis spectral analyses were carried out at various temperatures (Figure 3). van’t Hoff plots of the nucleation and elongation processes provided information on the enthalpic and entropic changes of each process, ΔHn, ΔSn, ΔHe, and ΔSe, respectively (Table 1).6a In each process, both the enthalpic and entropic changes are negative, suggesting that each process is enthalpically driven and entropically opposed. The enthalpic gain in the elongation regime is larger than that in the nucleation regime, which suggests that assembly of 1 is cooperative. The thermodynamic parameters (ΔHe and ΔSe) and the size of nuclei are close to the values obtained by van der Schoot’s mathematical model. The temperature- and concentration-dependent experiments and analyses based on UV−vis absorption spectra were also carried out in MCH (Figures 4 and 5). The results clearly show that 1 self-assembled in a cooperative fashion in MCH as well as in decalin. Thermodynamic Insight into Cooperative Assembly. The thermodynamic parameters of the self-assembly of 1 in chloroform, decalin, and MCH are summarized in Table 1. The self-assembly behaviors of 1 are dependent on the properties of
which represents the number of molecules in the nucleus at the transition from nucleation to elongation. The various-temperature UV−vis absorption at various concentrations of 1 provided the Ke(Te) value at each elongation temperature, which allowed the van’t Hoff plot of the elongation process (Figure 2g). The enthalpic and entropic contributions to the elongation (ΔHe and ΔSe) were determined to be −13.1(9) kcal mol−1 and −20(3) cal mol−1 K−1, respectively, suggesting that the elongation regime is enthalpically driven and entropically opposed. Although the analysis based on van der Schoot’s mathematical model using various-temperature UV−vis absorption spectra provides thermodynamic insight into the elongation, it does not provide information on the nucleation regime. On the other hand, the analysis based on the Goldstein−Stryer mathematical model using concentrationdependent UV−vis absorption spectra gave the association constants in the nucleation and the elongation processes (Kn and Ke), the cooperative factor (σ = Kn/Ke), and the size of the nuclei (s).13 Figure 3c shows the concentration-dependent UV−vis absorption spectra of 1 in decalin at 25 °C. Compound 1 exhibited a monomeric absorption band at 2.0 × 10−6 mol L−1. The intensity of the absorption band decreased and redshifted bands emerged as the concentration increased to 5.4 × 10−5 mol L−1, suggesting the formation of J-aggregates. The plot of αagg at 330 nm vs the logarithm of the product of Ke and total concentration of 1 (Ct) produced a nonsigmoidal curve, 10065
DOI: 10.1021/acs.joc.7b01520 J. Org. Chem. 2017, 82, 10062−10069
Article
The Journal of Organic Chemistry
Figure 5. Concentration-dependent UV−vis absorption spectra of 1 in MCH at (a) 35 °C, (b) 40 °C, (c) 45 °C, and (d) 50 °C. The concentrations of 1 are 0.6, 0.9, 1.2, 1.5, 1.6, 2.3, 2.6, 3.1, 4.0, 5.9, 9.9, 16.0, and 17.5 × 10−6 mol L−1. The arrows indicate the change in the spectra as the concentration increased. The plot of the degree of aggregation vs KeCT in MCH at (e) 35 °C, (f) 40 °C, (g) 45 °C, and (h) 50 °C. (i) A van’t Hoff plot of Ke. (j) A van’t Hoff plot of Kn.
conformational flexibility; a flexible host that loses a large amount of freedom by complexation results in a large α. The small α for 1 suggests that the conformation of 1 is quite ridged, which results in a small entropic cost for the assembly of 1. The positive value of TΔS0 suggests that desolvation entropically contributes to the assembly process. The linear relationship between TΔS0 and ΔH for chloroform, decalin, and MCH strongly indicates that the isodesmic assembly and the cooperative assembly, including nucleation and elongation regimes, have closely related mechanisms. The enthalpic gains, ΔH, depend on the solvent properties; ΔH decreases with decreasing solvent polarity in the order of the solvent polarity (Figure 6b). The solvation of the monomer and the assembly explain this result; more-polar solvents solvate the monomer and the assembly much more than less-polar solvents. The solvation stabilizes the monomer more than the assembly and interferes in the intermolecular association, which results in the lower enthalpic gain in polar solvents. As a result, the size of the assemblies of 1 cannot become large enough to transition from the nucleation regime to elongation in chloroform. In fact, 1 precipitated suddenly when its concentration exceeded 30 mmol L−1. Further analysis has been hampered by this precipitation, but the result might indicate that the observed isodesmic self-assembly of 1 in chloroform is a nucleation regime of the cooperative assembly and that the elongation triggers the precipitation of 1. It is noteworthy that the differences in the enthalpic gain in the nucleation and elongation processes (ΔΔH = ΔHe − ΔHn) are approximately
the solvent. Generally, ΔH and TΔS of closely related chemical processes, self-assembly in this case, have a linear relationship, which is known as enthalpy−entropy compensation.14 In the case of 1, the plot of TΔS vs ΔH displays a clear linear relationship for the three chosen solvents with a slope α of 0.58 and a TΔS0 intercept of 1.6 kcal mol−1 (Figure 6a). The slope α
Figure 6. (a) An enthalpy−entropy compensation plot of the selfassembly of 1 in chloroform (circle), decalin (triangle), and MCH (square). A line of best fit is displayed. (b) A plot of the enthalpy gain from the self-assembly of 1 vs dielectric constant of the solvents.
means that 42% of the inclement of ΔH contributes to increasing the stability of the assembly and the remaining 58% is canceled out by entropic loss. α for the self-assembly of 1 is quite small compared to common host−guest complexations (0.90, 0.86, 0.76, and 0.51 for cyclodextrin, glyme/podant, crown ether, and cryptand, respectively). α reflects the 10066
DOI: 10.1021/acs.joc.7b01520 J. Org. Chem. 2017, 82, 10062−10069
Article
The Journal of Organic Chemistry 5 kcal mol−1 both in decalin and in MCH, suggesting that the transition from the nucleation regime to the elongation regime is not affected by the solvents. Accordingly, solvationdesolvation might barely participate in the transition process. On the basis of the results of these thermodynamic studies, the energy landscape of the self-assembly of 1 is illustrated in Figure 7. In the monomeric state, 1 is highly solvated, and
Figure 7. Energy landscape of the self-assembly of 1.
molecules are well-separated from each other. Polar chloroform solvates monomeric 1 and stabilizes the monomer more than the less-polar solvents decalin and MCH. Compound 1 selfassembles to form stacked assemblies in an isodesmic manner in chloroform and in a cooperative manner in decalin and MCH, and the isodesmic assembly in chloroform corresponds to a nucleation regime of the cooperative assembly. The assembling processes are enthalpically favored and entropically opposed. The cooperative assembly contains two Gibbs free energies, ΔGn and ΔGe, and the elongation regime is thermodynamically more favored than the nucleation regime (ΔGn > ΔGe). The difference of the free energies (ΔΔG = ΔGe − ΔGn) imparts cooperativity onto the self-assembly of 1. Theoretical Study. Theoretical calculations were used to construct an electronic picture of the self-assembling system. The energy-minimized structures of a monomer and tetrameric and hexameric assemblies of 2, a methyl-substituted analog of 1, were obtained by the density functional theory (DFT) framework at the wB97XD/6-31G** level containing a longrange dispersion correction.15 The Gaussian 09 program package was employed for the computations.16 MCH was used as the solvent. The optimized structure of a monomer 2 is shown in Figure 8a. The sulfur atoms of benzotrithiophene and the oxygen and nitrogen atoms of isoxazole take trans conformations to suppress in-plane dipoles, which are more stable than the cis conformations by 0.77 kcal mol−1. Thus, the structures of oligomeric assemblies were optimized starting from the trans conformer. The energy-minimized structures of two tetramers, syn- and anti-24, are shown in Figure 8b,c. All molecules of 2 align themselves in the same direction in syn-24, whereas all molecules of 2 alternately stack in anti-24. The relative energy per molecule of anti-24 is lower than that of syn24 by 3.64 kcal mol−1, suggesting that the anti conformation is more stable than the syn conformation. In this context, the structure of hexameric assembly anti-26 was optimized (Figure
Figure 8. (a) Chemical structure of 2. Energy-minimized structures of (b) 2, (c) syn-24, (d) anti-24, and (e) anti-26 by DFT calculations at the wB97XD/6-31G** level.
8d), and the anti conformers are used in the following discussion. The results of the calculation are summarized in Table 2, where ΔEn indicates the electronic interaction energy Table 2. Complexation Energies of the Assembly of 2 Calculated by the DFT Method ΔEn (kcal mol−1)a 2 syn-24 anti-24 anti-26 a
0 −41.17 −44.80 −49.93
n denotes the number of molecules contained in the assembly.
per molecule for n-mer [ΔEn = (En − nE1)/n]. All the ΔEn values were negative, suggesting that the formation of assemblies is favorable. The Wiberg bond index (WBI) between S atoms is less than 0.0025, indicating that no bonding interactions exist between S atoms of stacked molecules.17 The stabilization of the assembly is probably caused by intermolecular interactions, including π−π stacking, dipole−dipole, and/or van der Waals interactions. The cooperativity of the assembly is strongly suggested by the fact that ΔE6 is more negative than ΔE4 by 5.13 kcal mol−1. Cooperativity of the nucleation−elongation system is often derived from dipole− dipole interactions; the growth of the assembly induces electronic polarization of the neighboring molecules, which results in enhancement of the dipole−dipole interactions.5,8 Thus, the dipole moments of the assemblies were calculated. 10067
DOI: 10.1021/acs.joc.7b01520 J. Org. Chem. 2017, 82, 10062−10069
Article
The Journal of Organic Chemistry
Figure 9. (a, b) SEM image of 1 on a glass plate. The samples were prepared by drop-casting (a) decalin and (b) MCH solutions of 1. (c) AFM image of 1 on mica. The size of the AFM image is 6 × 6 μm. The sample was prepared by spin-coating a chloroform solution of 1. (d) Height profile along the white line in part c.
Monomer 2 has a flat C3 symmetric structure, but the calculated structures of 2 were slightly bent to produce dipoles. Although the outer molecules of the optimized assemblies are highly distorted, the inner molecules are not as distorted; thus, the dipole moments of inner molecules were calculated. To discuss the induction of dipoles in the assembly, ΔD, the increases of the dipole moment due to the formation of the assemblies are calculated as the difference between the z-component of the dipole moment of an assembly and the sum of the dipole moments of the monomers. ΔD of the inner dimer of anti-24 and inner tetramer of anti-26 are increased by 0.1943 and 0.1426 D, respectively, relative to the monomer, indicating that the dipole moment is induced by the formation of the assembly. The enhancement of induced dipole−dipole interactions of the assemblies probably imparts cooperativity on the self-assembly. Morphology of the Assembly. The morphologies of the assemblies of 1 were observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The SEM image of the assemblies showed highly grown fibrils resulting from bundles of one-dimensional stacked assemblies of 1 (Figure 9a,b). The AFM images provided more detailed insights into the assembled structures. When the chloroform solution of 1 was spin-coated on mica, networked fibers with a uniform height of 2 nm were observed (Figure 9c,d). The height corresponded well with the diameter of 1, suggesting that 1 forms one-dimensional stacked assemblies.
assembly is enthalpically driven and entropically opposed in all solvents. An enthalpy−entropy compensation plot indicates that 1 self-assembles in closely related processes in chloroform, decalin, and methylcyclohexane. The enthalpic gains in lesspolar solvents are greater than that in polar solvents, which results in the formation of large assemblies in decalin and in MCH. The analysis based on concentration-dependent UV−vis absorption spectra suggested that the enthalpic gain is more in the elongation process than in the nucleation process, which drives cooperativity of the self-assembly of 1. Theoretical studies demonstrated that the assemblies are increasingly stabilized as the assemblies grow and that induced dipole− dipole interactions impart cooperativity on the self-assembly of 1. Cooperative self-assemblies based on intermolecular interactions other than hydrogen bonding have rarely been reported. This paper demonstrated that van der Waals interactions, including induced dipole−dipole interactions, can drive the cooperative assembly of planar π-conjugated molecules.
■
EXPERIMENTAL SECTION
2,5,8-Tris{3-(4-decyloxyphenyl)isoxazol-5-yl}benzo[b]trithiophene (1). To a stirred solution of 2,5,8-triethynylbenzo[b]trithiophene (3) (0.91 g, 6.1 mmol) and 4-decyloxyphenylchloroxime (4) (6.63 g, 24.5 mmol) in CH2Cl2 (3 mL) was added triethylamine (0.5 mL). The reaction mixture was stirred for 48 h at room temperature under an argon atmosphere. The reaction was quenched by the addition of a portion of water. After extraction with CH2Cl2, the organic layer was washed with saturated aqueous ammonium chloride and brine, dried over Na2SO4, and concentrated in vacuo. The crude product was purified by column chromatography on silica gel (10% EtOAc/hexane) and by GPC−HPLC to give the desired product 1 as a yellow solid (36 mg, 48%): mp 166−168 °C; 1H NMR (300 MHz, CDCl3) δ 7.35 (d, J = 8.7 Hz, 6H), 7.21 (s, 3H), 6.66 (d, J = 8.7 Hz, 6H), 6.28 (s, 3H), 3.84 (t, J = 6.9 Hz, 6H), 1.78 (quint, J = 6.9 Hz, 6H), 1.47−1.32 (m, 42H), and 0.92 (t, J = 6.6 Hz, 9H) ppm; 13C NMR (75 MHz, CDCl3) δ 163.6, 162.5, 160.6, 132.6, 130.7, 128.8,
■
CONCLUSIONS In conclusion, the self-assembling behavior of tris(phenylisoxazolyl)benzotrithiophene (1) was investigated in detail. Compound 1 self-assembled to form supramolecular stacks. In chloroform, 1 isodesmically self-assembled. On the other hand, 1 self-assembled in a cooperative manner in decalin and in MCH. Thermodynamic studies revealed that the self10068
DOI: 10.1021/acs.joc.7b01520 J. Org. Chem. 2017, 82, 10062−10069
Article
The Journal of Organic Chemistry
(5) (a) Filot, I. A. W.; Palmans, A. R. A.; Hilbers, P. A. J.; van Santen, R. A.; Pidko, E. A.; de Greef, T. F. A. J. Phys. Chem. B 2010, 114, 13667. (b) Kobko, N.; Dannenberg, J. J. J. Phys. Chem. A 2003, 107, 10389. (c) Kobko, N.; Paraskevas, L.; del Rio, E.; Dannenberg, J. J. J. Am. Chem. Soc. 2001, 123, 4348. (6) (a) van der Zwaag, D.; Pieters, P. A.; Korevaar, P. A.; Markvoort, A. J.; Spiering, A. J. H.; de Greef, T. F. A.; Meijer, E. W. J. Am. Chem. Soc. 2015, 137, 12677. (b) Ogi, S.; Fukui, T.; Jue, M. L.; Takeuchi, M.; Sugiyasu, K. Angew. Chem., Int. Ed. 2014, 53, 14363. (c) García, F.; Korevaar, P. A.; Verlee, A.; Meijer, E. W.; Palmans, A. R. A.; Sánchez, L. Chem. Commun. 2013, 49, 8674. (d) Smulders, M. M. J.; Schenning, A. P. H. J.; Meijer, E. W. J. Am. Chem. Soc. 2008, 130, 606. (7) (a) Hong, E. Y. H.; Wong, H. L.; Yam, V. W. W. Chem. - Eur. J. 2015, 21, 5732. (b) Tian, Y.-J.; Meijer, E. W.; Wang, F. Chem. Commun. 2013, 49, 9197. (c) Fernández, G.; Stolte, M.; Stepanenko, V.; Würthner, F. Chem. - Eur. J. 2013, 19, 206. (8) Ikeda, T.; Iijima, T.; Sekiya, R.; Takahashi, O.; Haino, T. J. Org. Chem. 2016, 81, 6832. (9) (a) Ikeda, T.; Masuda, T.; Takayama, M.; Adachi, H.; Haino, T. Org. Biomol. Chem. 2016, 14, 36. (b) Adachi, H.; Hirai, Y.; Ikeda, T.; Maeda, M.; Hori, R.; Kutsumizu, S.; Haino, T. Org. Lett. 2016, 18, 924. (c) Ikeda, T.; Takayama, M.; Kumar, J.; Kawai, T.; Haino, T. Dalton Trans. 2015, 44, 13156. (d) Haino, T.; Hirai, Y.; Ikeda, T.; Saito, H. Org. Biomol. Chem. 2013, 11, 4164. (e) Ikeda, T.; Masuda, T.; Hirao, T.; Yuasa, J.; Tsumatori, H.; Kawai, T.; Haino, T. Chem. Commun. 2012, 48, 6025. (f) Tanaka, M.; Ikeda, T.; Mack, J.; Kobayashi, N.; Haino, T. J. Org. Chem. 2011, 76, 5082. (g) Haino, T.; Tanaka, M.; Fukazawa, Y. Chem. Commun. 2008, 468. (10) (a) Kashiki, T.; Kohara, M.; Osaka, I.; Miyazaki, E.; Takimiya, K. J. Org. Chem. 2011, 76, 4061. (b) Molina-Ontoria, A.; Zimmermann, I.; Garcia-Benito, I.; Gratia, P.; Roldan-Carmona, C.; Aghazada, S.; Graetzel, M.; Nazeeruddin, M. K.; Martin, N. Angew. Chem., Int. Ed. 2016, 55, 6270. (11) (a) Antonijevic, I. S.; Janjic, G. V.; Milcic, M. K.; Zaric, S. D. Cryst. Growth Des. 2016, 16, 632. (b) Xiao, Q.; Sakurai, T.; Fukino, T.; Akaike, K.; Honsho, Y.; Saeki, A.; Seki, S.; Kato, K.; Takata, M.; Aida, T. J. Am. Chem. Soc. 2013, 135, 18268. (c) Bleiholder, C.; Werz, D. B.; Koppel, H.; Gleiter, R. J. Am. Chem. Soc. 2006, 128, 2666. (d) Kobayashi, K.; Masu, H.; Shuto, A.; Yamaguchi, K. Chem. Mater. 2005, 17, 6666. (e) Werz, D. B.; Gleiter, R.; Rominger, F. J. Am. Chem. Soc. 2002, 124, 10638. (12) Kashiki, T.; Shinamura, S.; Kohara, M.; Miyazaki, E.; Takimiya, K.; Ikeda, M.; Kuwabara, H. Org. Lett. 2009, 11, 2473. (13) Goldstein, R. F.; Stryer, L. Biophys. J. 1986, 50, 583. (14) (a) Ryde, U. MedChemComm 2014, 5, 1324. (b) Liu, L.; Guo, Q. X. Chem. Rev. 2001, 101, 673. (15) Chai, J.-D.; Head-Gordon, M. Phys. Chem. Chem. Phys. 2008, 10, 6615. (16) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, N. J.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö .; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09, Revision D.01; Gaussian, Inc.: Wallingford, CT, 2010. (17) Sizova, O. V.; Skripnikov, L. V.; Sokolov, A. Y. J. Mol. Struct.: THEOCHEM 2008, 870, 1.
128.0, 120.4, 120.3, 114.6, 98.1, 68.2, 32.2, 29.9, 29.9, 29.8, 29.6, 29.6, 26.4, 23.0, and 14.4 ppm; IR (KBr) 2923, 2852, 1612, 1575, 1530, 1493, 1467, 1431, 1389, 1295, 1251, 1176, 1115, 1089, and 1022 cm−1; HR-MS (APCI) calcd for C69H82O6N3S3 m/z = 1144.5360 [M + H]+, found m/z = 1144.5377. Anal. Calcd for C69H81N3O6S3: C 72.41, H 7.13, N 3.67, S 8.40. Found: C 72.18, H 7.00, N 3.65, S 8.25%.
■
ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.joc.7b01520. Experimental and computational details, NMR and UV− vis absorption spectra, results of DFT calculations, and 1 H and 13C NMR spectra of newly synthesized compounds (PDF)
■
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Fax: +81-82-424-0724. Tel: +81-82-424-7427. ORCID
Takeharu Haino: 0000-0002-0945-2893 Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS This work was supported by Grants-in-Aid for Scientific Research, JSPS KAKENHI Grant Numbers JP15H03817, JP15KT0145, and JP26810051 from the Japan Society for the Promotion of Science (JSPS), and by Grants-in-Aid for Scientific Research on Innovative Areas, JSPS KAKENHI Grant Numbers JP15H00946 (Stimuli-Responsive Chemical Species), JP15H00752 (New Polymeric Materials Based on Element-Blocks), JP17H05375 (Coordination Asymmetry), and JP17H05159 (π-Figuration). Funding from the Iketani Sciense and Technology Foundation is gratefully acknowledged.
■
REFERENCES
(1) (a) Aida, T.; Meijer, E. W.; Stupp, S. I. Science 2012, 335, 813. (b) Stupp, S. I.; Palmer, L. C. Chem. Mater. 2014, 26, 507. (c) Beaujuge, P. M.; Fréchet, J. M. J. J. Am. Chem. Soc. 2011, 133, 20009. (d) Hoeben, F. J. M.; Jonkheijm, P.; Meijer, E. W.; Schenning, A. P. H. J. Chem. Rev. 2005, 105, 1491. (e) Li, H.; Choi, J.; Nakanishi, T. Langmuir 2013, 29, 5394. (2) (a) De Greef, T. F. A.; Smulders, M. M. J.; Wolffs, M.; Schenning, A. P. H. J.; Sijbesma, R. P.; Meijer, E. W. Chem. Rev. 2009, 109, 5687. (b) Haino, T. Chem. Rec. 2015, 15, 837. (c) Serpe, M. J.; Craig, S. L. Langmuir 2007, 23, 1626. (3) (a) Haedler, A. T.; Meskers, S. C. J.; Zha, R. H.; Kivala, M.; Schmidt, H.-W.; Meijer, E. W. J. Am. Chem. Soc. 2016, 138, 10539. (b) Ogi, S.; Stepanenko, V.; Sugiyasu, K.; Takeuchi, M.; Würthner, F. J. Am. Chem. Soc. 2015, 137, 3300. (c) Kang, J.; Miyajima, D.; Mori, T.; Inoue, Y.; Itoh, Y.; Aida, T. Science 2015, 347, 646. (d) Ogi, S.; Sugiyasu, K.; Manna, S.; Samitsu, S.; Takeuchi, M. Nat. Chem. 2014, 6, 188. (4) (a) Martin, R. B. Chem. Rev. 1996, 96, 3043. (b) Smulders, M. M. J.; Nieuwenhuizen, M. M. L.; de Greef, T. F. A.; van der Schoot, P.; Schenning, A. P. H. J.; Meijer, E. W. Chem. - Eur. J. 2010, 16, 362. (c) Supramolecular Polymers, 2nd ed.; Ciferri, A., Ed.; CRC Press−Taylor & Francis: Boca Raton, FL, 2005. (d) Jonkheijm, P.; van der Schoot, P.; Schenning, A. P. H. J.; Meijer, E. W. Science 2006, 313, 80. (e) Zhao, D.; Moore, J. S. Org. Biomol. Chem. 2003, 1, 3471. 10069
DOI: 10.1021/acs.joc.7b01520 J. Org. Chem. 2017, 82, 10062−10069
