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Functional Nanostructured Materials (including low-D carbon)

Construction of Various Supramolecular Assemblies from Rod-Coil Molecules Containing Biphenyl and Anthracene Groups Driven by Donor-Acceptor Interactions Shengsheng Yu, Rui Shan, Guangyan Sun, Tie Chen, Lixin Wu, and Longyi Jin ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b01461 • Publication Date (Web): 12 Jun 2018 Downloaded from http://pubs.acs.org on June 12, 2018

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ACS Applied Materials & Interfaces

Construction of Various Supramolecular Assemblies from Rod-Coil Molecules Containing Biphenyl and Anthracene Groups Driven by Donor-Acceptor Interactions Shengsheng Yu1, Rui Shan1, Guang-Yan Sun1, Tie Chen1, Lixin Wu*2, Long Yi Jin*1 1

Key Lab for Organism Resources of the Changbai Mountain and Functional Molecules, and

Department of Chemistry, College of Science, Yanbian University, Yanji 133002, P. R. China 2

State Key Lab of Supramolecular Structure and Materials,

Jilin University, Changchun

130012, P. R. China *Corresponding author. E-mail address: [email protected] (L. Wu) [email protected] (L. Y. Jin)

ABSTRACT Rod-coil amphiphilic functional molecules, comprising of a rigid aromatic building block and hydrophilic oligoether dendrons as the coil segments, were synthesized. These compounds exhibit a powerful self-organizing ability to form supramolecular nanoparticles and long nanofibers in tetrahydrofuran (THF)/water solution, by controlling the inter-molecular interaction of the rigid blocks. These molecules are able to form supramolecular polymers and, subsequently, to form sheet-like nanoaggregates, through charge-transfer interactions by the addition of a guest molecule, tetracyanoquinodimethane. Notably, upon addition of water-soluble 2,4,6-trinitrophenol, the self-assembly of these molecules exhibit the antagonistic effect owing to

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ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

donor-acceptor

and

hydrophobic-hydrophilic

interactions

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among

the

molecules.

The

experimental results reveal that various morphologies of rod-coil molecular assemblies can be obtained by tuning the molecular interaction and the hydrophilicity of guest electron-acceptor molecules. Interestingly, the cross-coupling reaction between phenylboronic acid and chlorobenzene occurs within the charge complexes of these molecular aggregates. This occurs in the nanoenvironment that affords an extremely concentrated reaction zone and reduces the activation energy barrier required for the cross-coupling reaction. KEYWORDS: Rod-coil, Self-assembly, Charge complexes, Nanoreactor, Donor-acceptor INTRODUCTION Development of supra-molecular nanoassemblies with a specific shape is a new strategy to obtain nanoscale materials, the physicochemical property and functionality of which arise and strengthen owing to the spontaneous assembly of relatively small molecular building blocks.1-8 Therefore, construction of supramolecular assemblies or nanostructures is attracting a great deal of attention. These assemblies are widely used in various research areas such as catalysis,9-15 controlled release and drug delivery systems,16-23 molecular sensing,24-28 nanofabrication,29-36 antimicrobial materials,37 and tissue engineering.38-43 In particular, the π-conjugated rod-coil architecture of supramolecular assemblies has attracted increasing attention, owing to the strong capacity of rod-coil compounds to form highly ordered anisotropic and orientational nanoaggregates. For example, Lee et al. investigated the self-assembly of differently shaped conjugated rigid-flexible compounds, involving T-, propeller-,Y-, and cyclic-, and bent-shaped compounds.44-48 The various supramolecular nanostructures have been created by precisely tuning the assembling parameters, such as the of coil/rod volume ratio, cross-sectional area of


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the flexible segment, anisotropy of the rigid segment, and value of the lateral groups per rigid segment in the crystalline or liquid crystalline phase. Moreover, the construction of helical fibers, toroids, open porous sheet, helical tubules, 2-D flat sheet, temperature-sensitive tubules in selective solution environments has also been reported to occur via tuning of intermolecular driving forces of various rod-coil molecules, such as π-π stacking, electrostatic interactions, hydrogen bonding and hydrophobic-hydrophilic effects.

Recently, the amphipathic rod-coil architecture has been widely introduced to create supramolecular smart nanoaggregates for potential applications in producing biomimetic materials, drug carriers, and photochemical functional materials.49-53 The morphology of these assemblies significantly influences the bioactive or photo-electric properties in selective solutions. Lee and coworkers reported that amphipathic molecule with external mannose selforganizes into switchable, fluorescent fibers. Notably, the spontaneously assembled fibers release cells when the multivalent molecular interactions are tuned appropriately.54 Huang et al. have reported the external responsiveness of host-guest molecules comprising of azobenzene and pillar[7]arene units in aqueous solution. The self-assembly of nanostructures composed of nanoparticles and vesicles was reversible, depending on the system temperature or presence/absence of UV-Vis light irradiation. The dual-responsive vesicles have been applied to controlled the release of dye molecules in aqueous solution.55 Yan et al. have reported voltageresponsive reversible organization and disorganization of two end-decorated homopolymers. They demonstrated that different voltage strengths are able to control the disorganization rate of nanoobjects.56 The result further implies that the morphology of self-assembled amphiphilic molecules could be accurately controlled by tuning the hydrophobic-hydrophilic interactions and noncovalent intermolecular interactions.


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As one of the driving forces for molecular self-assembly, electron donor-acceptor interactions play an important role in the fabrication of various supramolecular assemblies in aqueous solution. For example, Huang and coworkers reported that amphipathic spherical molecules can be polymerized through electron donor-acceptor interactions by adding an electron-deficient compound, tetranitrofluorenone (TNF), to form polymers in aqueous solution.57 They also reported that electron donor-acceptor interactions would strengthen the molecular interaction and control the supramolecular nanostructures along with other intermolecular interactions, for instance, hydrophilic and hydrophobic or π-π stacking interactions. We have recently reported that amphiphilic compounds composed of pyrene and oligo(ethylene glycol) (OEG) as the coil segment self-organize into various supramolecular aggregates. Interestingly, small curving sheets and large sheet-like nano-objects were fabricated by adding TNF to above self-assembling molecular nanoaggregates.58 The results of this investigation imply that different self-organizing ordered assemblies can be manipulated by adjusting the cooperative interaction among rod-coil molecules, including the charge transfer interaction. Nevertheless, to our knowledge, there are only a few papers on the study of self-assembling behavior, of rod-coil amphipathic compounds controlled by charge-transfer interactions in selective solutions and their application in functional materials. For this reason, amphiphilic compounds 1 and 2, composed of 9-phenylanthracene units and biphenyl groups connected through acetenyl units at the 10-position of anthracene molecules as rigid segments, have been synthesized (Scheme 1). The morphology study of these molecules in the THF/water solution driven by electron-acceptor molecules such as tetracyanoquinodimethane (TCNQ) or 2,4,6-trinitrophenol (TNP) was investigated, and the effect of electron-acceptor interactions on the self-assembly of these compounds was evaluated.


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Scheme 1. structures of molecules 1 and 2.

EXPERIMENTAL SECTION Synthesis Synthesis of 1 and 2: Both these compounds were synthesized by a similar procedure. We are here describing the synthesis of molecule 1. 9-ethynyl-10-phenylanthracene (0.066 g, 0.23 mmol) and 4'-iodo-1,1'-biphenyl by incorporating oligoether dendron units at the 4 position of biphenyl (0.139 g, 0.197 mmol) were dispersed in tetrahydrofuran and triethylamine. The resulting solution was degassed. Then, copper(I) iodide (0.010 g, 0.05 mmol) and tetrakis(triphenylphosphine) palladium(0) (30 mg, 0.03 mmol) was added to the above solution. After allowing them to react for 24 hour under a nitrogen environment, the organic solution was poured into water and extracted with methylene chloride and ethyl acetate. Finally, 0.096 g pure target molecule 1 was obtained through column chromatography ( yield 57.1 %).1H-NMR (500 MHz, CDCl3, δ, ppm): 8.76 (d, J = 4.2 Hz, 2H), 7.84 (d, J = 4.2 Hz, 2H), 7.66-7.69 (m, 4H), 7.60-7.64 (m, 7H), 7.43-7.45 (m, 4H), 7.03 (d, J = 4.2 Hz, 2H), 4.11 (d, J = 2.5 Hz, 2H), 3.533.68 (m, 26H), 3.38 (s, 6H), 2.33-2.38 (m, 1H), 1.15-1.16 (m, 6H). MALDI-TOF-MS: m/z [M]+ 854.


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Molecule 2: yield 0.11g (77 %). 1H-NMR (500 MHz, CDCl3, δ, ppm): 8.76 (d, J = 4.2 Hz, 2H), 7.84 (d, J = 4.2 Hz, 2H), 7.67-7.69 (m, 4H), 7.60-7.64 (m, 7H), 7.43-7.45 (m, 4H), 7.03 (d, J = 4.2 Hz, 2H), 4.10 (d, J = 2.5 Hz, 2H), 3.53-3.64 (m, 28H), 3.37 (s, 6H), 2.43-2.47 (m, 1H). MALDI-TOF-MS: m/z [M]+ 826. RESULTS AND DISCUSSION Amphiphilic rod-coil molecules 1 and 2, consisting of 9-phenylanthracene and biphenyl units as rod segments and hydrophilic oligoether dendrons as coil fragments, were successfully prepared, using 2-(2-methoxyethoxy)ethanol, 4-hydroxy-4'-iodobiphenyl, and 9-bromo-10phenylanthracene as the starting materials. To evaluate the influence of alkyl groups between the rigid and flexible domains on the self-organizing behavior, we designed and synthesized molecule 1, through Sonogashira coupling reaction of 9-ethynyl-10-phenylanthracene and 4'iodo-1,1'-biphenyl by incorporating oligoether dendron units at the 4 position of biphenyl. The resulting molecular structures were confirmed through 1H-NMR (Figures S1 and S2) and MALDI-TOF-MS (Figures S3 and S4). Aggregation behavior in THF/water mixed solution Molecules 1 and 2 comprise of hydrophilic oligoether dendrons and hydrophobic conjugated rod fragments. Because of their amphiphilic characteristics, these molecules show a significant trend to produce supramolecular nanoaggregates in polar solutions.44-48 The aggregation behavior of amphipathic molecules 1 and 2 in THF/H2O (v/v = 3:7) was studied by UV-Vis and fluorescence spectroscopy. The UV-Vis spectra for 1-2 in the THF/H2O exhibit a redshift at 441 nm and 440 nm, respectively, compared with those obtained using dichloromethane solution (438 nm). This can be ascribed to the conjugated rod block in different solvent environments.58


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Figure 1 and Figure S5 show the emission spectra of 1 and 2 with a strong emission maximum in dichloromethane solution. The emission maxima in the THF/H2O solution are significantly quenched in relation to that shown in the methylene chloride solution. This indicates the molecular arrangement caused by the conjugated rod segments. The critical aggregation concentrations of 1 and 2 determined by concentration dependent UV-Vis experiments were about 0.008 and 0.009 mg/mL, respectively (Figures. S6 and S7). DLS results further demonstrate this experimental phenomenon. The mean diameters of the nano-objects from selfassembly of 1 and 2 were displayed ~58 nm and ~522 nm, respectively (Figure S8).

Figure 1. UV-Vis and FL spectra of 1 in dichloromethane (dashed) and THF/H2O (v/v = 3:7) (solid) solution (0.01 wt %). To gather detailed data on the aggregation behavior of these molecules, transmission electron microscopy (TEM) and atomic force microscope (AFM) measurements were performed in dilute


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THF/H2O solution. The samples for TEM were cast from the mixed solution of 1 and 2 molecules (0.01 wt %). The TEM image of the assembly of 1 with methyl units located between the rigid and flexible segments, shown in Figure 2a, clearly exhibit nanoparticles with a width of 30-50 nm. However, the TEM micrograph of molecule 2, which does not have any lateral methyl groups at the oligoethylene dendron unit, displays nanofibres with a mean width of ~5 nm, and lengths of up to several hundred nanometers (Figure 2b). The entire length of 2, simulated by using the Corey-Pauling-Koltun (CPK) molecular model, is 3.6 nm, more than half of the measured width of the nanofiber by self-assembly of 2. This indicates that the nanofiber core composed of the rod-building block is surrounded by flexible hydrophilic oligoethylene dendrons in polar mixed solvents. AFM experiments also confirm that 1 and 2 self-organize into nanoparticles and nanofibres in THF/H2O solution, respectively (Figure S9). An interesting phenomenon, observed from TEM and AFM studies of molecular self-assemblies, is that methyl units located between the rigid and flexible segments may impose steric constraints.59 In contrast to 2, the steric constraint leads to decreased intermolecular interactions in the case of 1 and subsequently results in the formation of nanoparticles from the assembly of the rigid segment of molecule 1. This process is achieved by minimizing the energy balance of 1, which is caused by intermolecular interactions of the rigid aromatic parts and the repulsive effect exerted by chiral oligoethylene dendron segments.


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Figure 2. TEM images of 1-2 a) 1; b) 2, cast from a 0.01 wt % THF/H2O (v/v = 3:7) solution. As a favorable electron donor material, π-conjugated molecules have a strong capacity to produce supramolecular molecules with electron-acceptor molecules driven by donor-acceptor interactions,60,61 such as TCNQ and TNP. Supramolecular polymers based on electron donoracceptor interactions are able to held together along the stacking axis and generate hierarchical nanostructures when intermolecular interactions are enhanced.57 To confirm the synergistic effect of the charge transfer interaction and hydrophilic-hydrophobic effect on the self-assembly of 1 and 2, we conducted self-assembling studies of 1 and 2 by adding TCNQ and TNP in the THF/water solution. DLS analysis shows that 1 and 2 with 1.0 equiv. TCNQ produce nanoassemblies, which have mean diameters 712 nm and 821 nm, respectively (Figure S10). The observed mean diameters of 1:1 complexes of 1 and 2 with TCNQ are larger than those of molecules 1 and 2, implying the formation of charge transfer complexes. To further confirm this result, UV-Vis and fluorescence spectroscopies were performed using sample complex. Figure 3 shows the UV-Vis and FL spectra of 1 (0.01 wt %), upon adding TCNQ in the THF/H2O (v/v = 3:7) solution. As shown in Figure 3a, the intensity of the fluorescence emission was abruptly quenched, when the TCNQ concentration was increased, indicating the formation of molecular


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assemblies. Interestingly, upon the addition of TCNQ, the absorption spectra of 1 display new gradually enhancing absorption peaks at 750 nm. This demonstrates the formation of donoracceptor complexes with electron-acceptor molecules, via charge-transfer interactions. Subsequently, we carried out 1H-NMR experiments for determining the position of the molecular interaction between the TCNQ and the aromatic units within the rod-building block (Figure S11). The proton peaks attributable to the anthracene unit shift highfield, demonstrated that TCNQ is connected to the anthracene unit through charge transfer interactions. No change in the proton signals of biphenyl groups was observed, implying that only the anthracene unit interacts with TCNQ to form charge transfer complexes. Similar experimental results were observed during the investigation of the self-assembling behavior of molecule 2 with electron-acceptor TCNQ (Figures S12 and S13).


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Figure 3. FL (a) and UV-Vis (b) spectra of 1, upon adding TCNQ in THF/H2O (v/v = 3:7) solution (0.01 wt %). To clearly identify the morphological aggregates upon the addition of TCNQ in the THF/water solution, TEM study of complexed compunds of 1 and 2 was carried out at room temperature. The micrographs of the samples cast from mixed solution of these molecules in diluted solution showed sheet-like nanoaggregates, which have mean width of ~0.6µm and length of ~1.0 µm, for molecules 1 and 2 (Figure 4). This indicates that sheet-like nanoaggregates are produced from nanoparticles and nanofibers upon the addition of TCNQ, driven by the strong charge transfer interaction among the molecules. Although the methyl groups located between the rigid and flexible segments significantly influence the formation of molecular assemblies in diluted


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solution, when TCNQ is added, this effect is dramatically suppressed instead of strong donoracceptor interactions. The result implies that the donor-acceptor interaction is one of the primary parameters that determined the driving forces for the construction of supramolecular nanoassemblies of 1 and 2 in the presence of TCNQ. It can be reasonably explained based on the formation of nanosheet-like aggregates of complexes of 1 and 2. In contrast to molecules 1 and 2, their complexes exhibit a strong self-assembling driving force enhanced by charge transfer intermolecular interaction as well as by π-π stacking in molecules 1 and 2. This creates a curvature in the rod-building block; however, in diluted mixed solution, the hydrophobic domains are more flatter than highly curved 1 and 2. Thus, complexes of 1 and 2 with a less interfacial area than molecules of 1 and 2 tend to self-assemble into more dynamic stable sheetlike nanoaggregates.

Figure 4. TEM image of molecules 1-2 (a) 1, (b) 2, cast from a 0.01 wt % THF/H2O (v/v = 3:7) solutions of 1-2 with 1.0 equiv. TCNQ. As mentioned above, charge-transfer interaction would strengthen the intermolecular forces by adding

electron-deficient

compounds

to

create

supramolecular

polymers

and

their

nanoaggregates. To investigate the impact of hydrophilic acceptor-type small molecules on the


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self-assembling behavior of 1 and 2 in the THF/water diluted solution, we performed selfassembling study of complexes of 1 and 2 with the hydrophilic electron-acceptor molecule TNP. Upon the addition of TNP to the THF/H2O (v/v = 3:7) solutions of 1 and 2, the fluorescence emission of similar complexes of 1-2 with TCNQ quenched (Figures 5a and S14a, respectively); this is indicative of the formation of the complex molecules within the aromatic core via chargetransfer interaction. The absorption spectra of 1-2 in mixed solution gradually enhanced and slightly red-shifted (Figures 5b and S14b), implying the more planar-conformation aromatic domains that are preferentially formed by the addition of a certain amount of TNP. 1H-NMR experiments provided further evidence of the formation of donor-acceptor charge transfer complexes of 1-2 (Figures S15 and S16). Notably, the results revealed that the signal peaks of the proton response to both anthracene and biphenyl units shifted highfield, demonstrating that anthracene and biphenyl units combined with the TNP, through charge transfer interaction.


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Figure 5. FL (a) and UV-Vis (b) spectra of 1, upon adding TNP in THF/H2O (v/v = 3:7) solution (0.01 wt %).


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Figure 6. TEM image of molecules 1-2 (a) 1, (b) 2, cast from a 0.01 wt % THF/H2O (v/v = 3:7) solutions of 1-2 with 1.0 equiv. TNP. To gain an insight into the definite formation of charge transfer interaction between molecules 1 and 2 with TNP, Gaussian 09 program package was used.62 Figure S17 shows the molecular surface electrostatic potential distribution based on the optimal molecular configuration of the ground state. The image visually displays the spread of negative electrostatic potential over the entire rod segment, and shows that benzene ring c within the biphenyl unit is relatively more negative than benzene rings a and b of the anthracene unit. Thus, we estimated that the small molecule TNP combined with benzene rings a-c to produce charge transfer complexes of molecules 1 and 2. DLS and TEM experiments were performed to determine how TNP affects the self-assembly of 1-2 in the THF/water solution. To our surprise, DLS analysis showed that molecules 1 and 2 with 1.0 equiv. TNP self-organize into nano-objects with the mean diameters 10 nm and 28 nm, respectively (Figure S18). This means that the aggregative morphology of 1-2 with TNP is significantly changed, compared with the formation of sheet-like nanoaggregates of complexes of 1-2 with TCNQ. Detailed information of their molecular morphology is provided by TEM. The TEM images of complexes of 1-2 with TNP display spherical micelles and nanoparticles with the average diameters ~5 nm and 15-20 nm, respectively (Figure 6). Generally, the more planar-conformation of rod domains was created by donor-acceptor interactions, because of the restricted rotational freedom when TCNQ is added to molecules 1 and 2. Nevertheless, hydrophilic TNP loaded at the diphenyl and anthracene units of the rod segments would strengthen the intermolecular steric constraints and hydrophilic interactions. Therefore, the hydrophilic-hydrophobic interface of aggregates would transform from a flatter interface to a highly curved interface, to lower the total free energy. Thus, the complexes of 1 and 2 with 1.0


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equiv. TCNQ self-assemble into a sheet structure; however, these molecules self-assemble into micelles and nanoparticle with 1.0 equiv. TNP, respectively. Although the formation mechanisms of molecules 1 and 2 with TNP is not clear, the results of self-assembly of these molecules imply that steric constraints and hydrophilic interaction are the main factors affecting the construction of nanoassemblies than donor-acceptor interactions when hydrophilic TNP is added to molecules 1 and 2. Table 1. Suzuki cross-coupling reaction in THF/H2O (v/v = 3:7) solution a

a

Reaction conditions: chlorobenzene or 4-chloronitrobenzene (0.05 mmol), phenylboronic acid

(0.06 mmol), palladium acetate (0.5 mol %),

triphenylphosphine

(1.0 mol %), sodium


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hydroxide (0.2 mmol), R (0.0125 mmol), and THF/H2O (v/v = 3:7) (5 mL), reacted at ambient temperature for 2 h. b Yields are determined by the GC-MS data. It has been demonstrated that the rod-coil molecular aggregates composed of conjugated aromatic segments have nanoscale sites appropriate for restricting on aromatic guest compounds. The capture of guest molecules is attained through π-π interactions, one of the non-covalent driving forces.63,64 However, aryl chlorides are unavailable for the Suzuki coupling reaction unlike their bromic or iodic substitutes under the same reaction environment.65 Hence, the feasibility study on a nanoreactor composed of rod-coil electron-transfer complexes was performed with the cross-coupling reaction of chlorobenzene and phenylboronic acid in the THF/H2O mixture solution. The results of Suzuki cross-coupling reaction is summarized in Table 1 and Table S1. Interestingly, the cross-coupling reaction of phenylboronic acid and chlorobenzene occurred in the THF/H2O (v/v = 3:7) solution. This indicate that the electrontransfer complexe is highly effective (providing 3-fold high yield) for the cross-coupling reaction at ambient temperature, compared to the results obtained when only TNP, TCNQ, molecules 1 and 2, TCNQ, or anthracene is added. To further confirm the efficiency of these charge-transfer nanoreactors for Suzuki cross-coupling reaction, we carried out cross-coupling reaction of phenylboronic acid and chlorobenzene with electron-rich or deficient groups at the para position of the chlorobenzene. As shown in Table S2, the 2-fold yields of products were obtained from the cross-coupling reaction of phenylboronic acid and 4-chloroanisole which is an inactive substrate for the Suzuki cross-coupling reaction. Notably, under the same reaction environment, the higher yields (up to 59.2%) are achieved from the Suzuki cross-coupling reactions of phenylboronic acid and 4-chloronitrobenzene, using electron-transfer complexes of 1 and 2 as supramolecular nanoreactors (Table 1 and Table S3). The restriction of aryl substrates at the


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intermolecular space of electron-transfer complexes may be a keypoint to take place of Suzuki cross-coupling reaction. The aromatic substrates can enter the rod segment and are then confined by π-π and hydrophobic interactions. Subsequently, the cross-coupling reaction successfully takes place, owing to the confined space that induces an extremely concentrated reaction site, and lowers the activation energy required for the Suzuki cross-coupling reaction.

Figure 7. Cartoon representation of supramolecular nanoassemblies of 1-2 and supramolecular nanoreactor.


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CONCLUSION We have demonstrated that amphiphiles 1-2 self-organize into nanoparticles and long nanofibres in the THF/water solution, respectively. Sheet-like supramolecular polymers was formed from self-assembly of these nanoobjects, driven by charge-transfer interaction through the addition of TCNQ. However, upon the addition of hydrophilic TNP, the results obtained were in contrast to those obtained when TCNQ was added. Complexes of 1-2 with TNP selforganize into nanoparticles and micelles in the THF/water diluted solution. These results indicate that rod-coil molecular nanoassemblies can be accurately controlled by adjusting the assembly parameters, for instance, charge transfer interaction and hydrophilic-hydrophobic effects, and by incorporating peripheral small side chains in the rod-coil system. The control of the supramolecular polymer morphology by charge-transfer interactions may provide new opportunities to create more complicated functional supramolecular materials. We also found that the complexes of 1-2 can be used as a nanoreactor for the cross-coupling reaction of chlorobenzene derivatives and phenylboronic acid in a polar solution. The nanoreactor provides a nanoenvironment, i.e., a concentrated reaction space and lowers the activation energy required for the Suzuki cross-coupling reaction. We believe that the strategy of using charge-complex rod-coil molecular aggregates as efficient nanoreactor will provide a useful way to synthesize organic compounds. ASSOCIATED CONTENT * Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsami.xxxxxx. Experimental details; Figures S1-S18 and Tables S1-S3


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AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] *E-mail: [email protected] Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China (grant number 21562043, 21564016).

REFERENCES (1) Stoddart, J. F. From Supramolecular to Systems Chemistry: Complexity Emerging out of Simplicity. Angew. Chem. Int. Ed. 2012, 51, 12902-12903. (2) Srinivasan, S.; Praveen, V. K.; Philip, R.; Ajayaghosh, A. Bioinspired Superhydrophobic Coatings of Carbon Nanotubes and Linear π Systems Based on the “Bottom-up” Self-Assembly Approach. Angew. Chem. Int. Ed. 2008, 47, 5750-5754. (3) Williams, R. J.; Smith, A. M.; Collins, R.; Hodson, N.; Das A. K.; Ulijn, R. V. EnzymeAssisted Self-Assembly under Thermodynamic Control. Nat. Nanotechnol. 2009, 4, 19-24. (4) Fielden, S. D. P.; Leigh, D. A.; Woltering, S. L. Molecular Knots. Angew. Chem. Int. Ed. 2017, 56, 11166-11194.


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