Next Article in Journal
Catalytic Valorisation of Biomass-Derived Levulinic Acid to Biofuel Additive γ-Valerolactone: Influence of Copper Loading on Silica Support
Previous Article in Journal
Various Techniques for the Synthesis of 2-Nitrophenylamino-1,4-naphthoquinone Derivatives
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Reactions
Volume 4
Issue 3
10.3390/reactions4030027
reactions-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

One-Pot Synthesis of Stable Poly([c2]Daisy–chain Rotaxane) with Pseudo-Stopper via Metathesis Reaction and Thiol-Ene Reaction

by
Risako Kamoto
,
Kenjiro Onimura
and
Kazuhiro Yamabuki
*
Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube 755-8611, Yamaguchi, Japan
*
Author to whom correspondence should be addressed.
Reactions 2023, 4(3), 448-464; https://doi.org/10.3390/reactions4030027
Submission received: 12 July 2023 / Revised: 3 August 2023 / Accepted: 17 August 2023 / Published: 23 August 2023
Browse Figures
Versions Notes

Abstract

:
Rotaxanes, known as supramolecular compounds, are expected to find applications in functional materials due to their high degree of freedom. However, their synthesis requires multistep reactions, and there is a demand for more convenient methods to synthesize rotaxane materials. In this study, we aimed to investigate a simpler method for synthesizing highly functional rotaxane materials and explore the diversity of molecular designs. To achieve this, we successfully synthesized a host–guest conjugated compound that incorporates both crown ether as the host unit and secondary ammonium salts as the guest unit within the same molecule. Subsequently, the metathesis reaction of these compounds, which construct [c2]daisy-chain rotaxanes, enabled the one-pot synthesis of a topological polymer called “poly([c2]daisy-chain rotaxane)” with a pseudo-stopper. This methodology achieves the stabilization and polymerization of rotaxanes simultaneously, contributing to the easy materialization of rotaxanes. Furthermore, the thiol-ene reaction achieved the extension of the distance between rotaxane units and provided a useful approach to diversify the design of functional materials with rotaxane structures.

1. Introduction

Rotaxanes are a well-known type of supramolecular structures that exhibit organized arrangements through interactions between molecules. A rotaxane is a general term for a mechanically interlocked molecule where a linear molecule (known as the “axle”) threads through the cavity of a cyclic molecule (referred to as the “wheel”), and numerous rotaxanes have been reported to date. For instance, Harada et al. have reported a typical rotaxane shaped like a necklace by utilizing hydrophilic cyclodextrins as a host and incorporating an axle such as polyethylene glycol into the cavity [1,2,3,4,5,6,7,8,9,10,11]. These systems take advantage of the complementary sizes and hydrophobic interactions between the host and guest molecules, allowing for the formation of precisely controlled complexes. On the other hand, research on rotaxanes using hydrophobic cyclic molecules, with a focus on Stoddart and Gibson et al.’s work, has been actively reported since the 1990s [12,13,14,15,16,17,18,19,20,21,22,23]. Through cyclodextrins, various interactions can be utilized for the synthesis of rotaxanes. For example, Stoddart et al. successfully synthesized a rotaxane consisting of a 4,4′-bipyridinium unit and a bisparaphenylene-34-crown-10 macrocycle, utilizing charge–transfer interactions [15]. Gibson et al. found that a 30-membered crown ether forms hydrogen bonds with hydroxyl groups at the polymer chain termini, promoting rotaxane formation [21]. Furthermore, Sauvage et al. reported the synthesis of rotaxanes using the coordination structure of Cu ion and crown ether derivatives with phenanthroline skeleton, establishing an efficient synthesis method utilizing the template effect between a metal ion and a ligand [18]. Additionally, Takata et al. reported the synthesis of hydrophobic functional rotaxanes utilizing hydrogen bonds and electrostatic interactions working between the secondary ammonium salt axles and the dibenzo-24-crown 8-ether (DB24C8) derivatives [24,25,26]. They demonstrated the utilization of these rotaxanes not only in small molecules but also in functional polymer materials. Supramolecular compounds utilizing intermolecular interactions, such as rotaxanes, exhibit ordered spatial arrangements and are recognized as artistic compounds. However, in recent years, various functional rotaxane materials with excellent properties, like slide-ring gels, have also gained significant recognition [27,28,29,30,31,32,33,34,35]. In slide-ring gels, the cyclodextrins within the rotaxane form a hydrogel through intermolecular cross-linking [36]. This hydrogel structure allows the cyclodextrins to freely move along the polyethylene glycol (PEG) axle, effectively mitigating external forces (“Pulley effect”). As a result, these materials exhibit high mechanical strength and stretchability, offering unique functional materials based on a novel concept that distinguishes them from both chemical gels and physical gels. In maintaining the structure and functionality of these rotaxanes, a bulky “stopper” is essential as a third component other than the wheel and axle (Figure 1).
A “stopper” possesses a size larger than the cavity size of wheel and serves the role of enclosing wheel within the rotaxane. By introducing these bulky compounds at the end of axle, the rotaxane can stably exist without dissociating in various external environments. Therefore, these stoppers are an essential component in the synthesis of many rotaxanes. However, the use of stoppers increases the complexity of the rotaxane synthesis process and leads to lower yields. Therefore, synthesizing rotaxanes efficiently using a simpler method holds significant industrial importance. To address the challenge of simplifying the synthesis of rotaxanes mentioned above, our research group focused on [c2]daisy-chain rotaxanes, which possess a unique structure among rotaxanes [37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62]. [c2]Daisy-chain rotaxanes are constructed from a host–guest connected compound (H-G compound) where the host component (wheel) and the guest component (axle) are incorporated within the same molecule. In these [c2]daisy-chain rotaxanes, two H-G compounds interact with each other, utilizing their wheel and axle components to mutually form an inclusion complex, resulting in a highly symmetrical compound. Such [c2]daisy-chain rotaxanes exhibit changes in the position of their internal wheels only when stoppers are introduced, in response to external stimuli such as light, pH, temperature, solvent polarity, and mechanical stress. These topological changes enable the creation of new materials with various functionalities such as stimulus responsiveness and stretchability, but there are very few reported examples of such materials [63,64,65,66,67,68,69,70]. Among them, for example, Stoddart et al. reported the synthesis of stable [c2]daisy-chain rotaxanes by introducing a 1,3-Diisopropylbenzene stopper containing an alkyne unit to the host–guest inclusion complex of crown ether and ammonium salt [71]. Furthermore, the rotaxane was successfully polymerized using Huisgen 1,3-dipolar cycloaddition, resulting in the synthesis of a topological polymer “poly([c2]daisy-chain rotaxane)” that allows for precise control of the position of the crown ether. However, this method involves a conventional two-step synthetic approach, where stable rotaxanes are first synthesized and purified using stoppers, followed by polymerization with diazides as joint components. Therefore, a more convenient synthetic approach is desired.
Based on this background, in recent years, we have successfully achieved the one-pot synthesis of a convenient and stable topological material using the [c2]daisy-chain rotaxane structure without employing a third ”stopper”. In this study, we report the one-pot synthesis of a polymer composed of continuously linked [c2]daisy-chain rotaxanes using only monoalkene compounds that contain a 24-membered crown ether (wheel) as the host component and a secondary ammonium salt (axle) as the guest component within the same molecule, utilizing metathesis reactions [72,73,74,75,76,77,78,79,80] (Figure 2).
The key point of our synthetic strategy is the synthesis of a rotaxane polymer using a simple and non-dissociating inclusion structure with only a single compound. In this strategy, the bulky [c2]daisy-chain rotaxane itself acts as a stopper (pseudo-stopper), suppressing the dissociation of another neighboring [c2]daisy-chain rotaxane unit. In other words, the [c2]daisy-chain rotaxane plays a dual role, as an inclusion complex and a stopper, enabling the one-pot synthesis of topological polymers with a single compound. In addition, we report the results of conducting thiol-ene reactions using dithiols to investigate the influence of distance extension between [c2]daisy-chain rotaxane units within the polymer backbone [81,82,83,84,85].

2. Results and Discussion

2.1. Design of H-G Monomer and Preparation of [c2]Daisy-chain Rotaxane

In order to achieve the one-pot synthesis of a poly[c2]daisy-chain rotaxane without using a third stopper compound, an H-G monomer was synthesized according to Scheme 1.
There are two key features in the molecular design here. The first is the length of the alkyl chain connecting the DB24C8 and ammonium salt units. To efficiently form the [c2]daisy-chain structure between the two molecules, it is most preferable to have a length of a methylene (-CH2-) for the alkyl chain, as reported for the quantitative formation of [c2]daisy-chain rotaxanes, benefiting from both the size complementarity and the π–π interactions between the benzene rings of DB24C8 [29,30,31,32,33,35,36]. The second feature is the incorporation of a low-radical-polymerizable terminal alkene. Long-chain alkenes without an electron-withdrawing group introduced on the adjacent carbon of the double bond easily undergo reactions involving metal coordination due to the presence of highly electron-dense double bonds while also providing high solubility in organic solvents to the entire compound. Additionally, this molecular design can easily achieve polymerization of [c2]daisy-chain rotaxane using only one compound (H-G monomer) through metathesis reactions that enable the exchange of double bonds between molecules.
The H-G monomer was successfully synthesized from 3,4-Dioxa-1,8-octanediol, two 1,2-dihydroxybenzene derivatives, and 10-undecene-1-amine in a total of 7 steps. Its structure was identified through NMR and MS measurements.
Figure 3 shows the 1H NMR spectra of H-G monomer in DMSO-d6 and CDCl3. Noticeable differences were observed between the two deuterated solvents, clearly indicating the presence or absence of inclusion complexes.
In highly polar solvents such as DMSO (Figure 3A), where hydrogen bonding and electrostatic interactions between the ammonium salt and crown ether are hindered, a spectrum similar to that of the original H-G monomer was observed. Consequently, the peaks corresponding to the methylene protons a–c derived from the ethylene oxide of the crown ether, located at 4.2–3.5 ppm, and the methylene proton units d and e adjacent to the ammonium salt, became sharper and were attributed in detail.
In contrast, in the less polar solvent chloroform (Figure 3B), the assigned regions mentioned above exhibited complex splitting patterns. This is a typical peak splitting behavior observed in [c2]daisy-chain rotaxane structures, indicating the complex contribution of peak shifts and conformational changes of the DB24C8 units due to the inclusion [41]. Furthermore, even when the concentration of H-G monomer was diluted 100-fold (0.001 M), no change in the spectral shape was observed, suggesting the quantitative and stable formation of the [c2]daisy-chain rotaxane structure in chloroform (see Figure S1 in Supplementary Materials).

2.2. One-Pot Synthesis of Poly([c2]Daisy-chain Rotaxane) by Using Metathesis Reaction of H-G Monomer

Next, metathesis reactions of the H-G monomer in chloroform as a low-polarity solvent were conducted (Scheme 2). Metathesis reactions are known as powerful tools for the rearrangement of double bonds and are widely used in various molecular designs.
In this reaction, the simultaneous formation of inclusion complexes and their polymerization allows for the synthesis of stable rotaxane materials consisting of the wheel and axle components. However, a small amount of products that do not dissolve in chloroform or other organic solvents was also present. The 1H NMR spectrum of the chloroform-soluble part obtained through metathesis reactions is shown in Figure 4. The spectrum of the product in CDCl3 (Figure 4A) exhibited complex splitting peaks at 4.2–3.5 ppm, similar to those of the spectrum of the [c2]daisy-chain rotaxane before the reaction (Figure 3A). Furthermore, a significant decrease in the proton peaks f and g derived from terminal double bonds at 5.8 and 5.2 ppm, respectively, and the appearance of a new proton peak h attributed to an internal double bond were observed. These observations suggest that the metathesis reaction of H-G monomer was carried out while maintaining the [c2]daisy-chain rotaxane structure. In the spectrum of the products in DMSO-d6 (Figure 4B), the complex peak splitting observed in CDCl3 changed to three distinct peaks a–c. This indicates a conformational change in the [c2]daisy-chain rotaxane, where the polar solvent DMSO strongly solvates the secondary ammonium salt unit in the rotaxane, causing the wheels to adopt a conformation that expands their distance to avoid steric hindrance without dissociating the rotaxane.
The molecular weight of the obtained products was estimated using GPC measurements (Figure 5). As a result, a trimodal peak was observed at significantly different retention times from that of H-G monomer (Mn = 670). The average molecular weights of the trimodal peak were determined to be Mn = 4700 and Mw = 5730, with the highest molecular weight region (the filled peak area) calculated as max. Mn = 8020 and max. Mw = 8830. This indicates that the resulting products were polymers of different lengths with multiple connected [c2]daisy-chain rotaxane units, and these polymers exist stably without dissociation.
These results demonstrate that in the metathesis reaction of H-G monomer using chloroform as the reaction solvent, both the inclusion and the polymerization reactions occur simultaneously, resulting in the formation of a high-molecular-weight polymer. In this process, adjacent [c2]daisy-chain rotaxane units act as bulky stoppers, affording the polymer to be maintained without dissociation.

2.3. One-Pot Synthesis of Poly([c2]Daisy-chain Rotaxane) by Using Thiol-Ene Reaction of H-G Monomer

In the polymerization of [c2]daisy-chain rotaxane through metathesis reaction, the obtained product showed low solubility in chloroform and a small amount of insoluble material was observed, indicating the high crystallinity of the polymer. Therefore, we investigated the change in molecular weight when introducing 3,6-dioxa-1,8-dithiol (DODT), a low-crystalline dithiol molecule, as a spacer component between [c2]daisy-chain rotaxane units (Scheme 3). H-G monomer, DODT, and benzophenone were dissolved in chloroform, and upon UV irradiation, a light-yellow solid product, poly([c2]daisy-chain rotaxane)-SH, was obtained.
The 1H NMR spectrum of poly([c2]daisy-chain rotaxane)-SH exhibited a significant decrease in the proton peaks f and g originating from double bonds, as well as the same complex splitting peaks observed in poly([c2]daisy-chain rotaxane), suggesting the progression of the thiol-ene reaction during the formation of the inclusion complex (Figure 6).
Figure 7 shows the GPC chart of the obtained product. The chart displayed a trimodal peak, and the overall average molecular weight was Mn = 4700, Mw = 5730. Furthermore, the peak corresponding to the high-molecular-weight region (the filled peak area) was calculated as max. Mn = 11,680, max. Mw = 16,660.
These results indicate that the thiol-ene reaction system can achieve both the formation of [c2]daisy-chain rotaxane and the suppression of dissociation through the connection of rotaxanes mediated by the dithiol, resulting in a molecular weight approximately 1.5 times higher than that obtained via a metathesis reaction. This suggests that the introduction of liquid DODT components into the polymer backbone decreases the overall crystallinity and improves solubility in organic solvents. Additionally, the DSC measurement of poly([c2]daisy-chain rotaxane)-SH determined a glass transition temperature (Tg) of 43 °C, while no corresponding endothermic peak was observed in the temperature range of 20–100 °C for the polymer obtained via a metathesis reaction (see Figure S2 in Supplementary Materials).
As the final experiment of this report, we carried out a deionization (neutralization) reaction of the highly soluble poly([c2]daisy-chain rotaxane)-SH (Scheme 4). The purpose of the neutralization reaction was to chemically remove the interaction between the ammonium salt and the crown ether that affects the [c2]daisy-chain rotaxane structure. We intentionally created an environment where the [c2]daisy-chain rotaxane could not be maintained and examined whether the polymer would disassembly.
The neutralization reaction was performed using acetic anhydride, and through IR measurements, typical absorption peaks related to the decrease in PF6 anions and the appearance of amide bonds confirmed the partial progression of the neutralization reaction (see Figure S3 in Supplementary Materials). In the 1H NMR spectrum of the neutralized poly([c2]daisy-chain rotaxane)-SH, three distinct peaks a–c attributed to the crown ether were observed in the range of 4.2 to 3.6 ppm in CDCl3 (Figure 8).
This showed a similar chemical shift as the inclusion part in DMSO in Figure 3B, suggesting a topological change in [c2]daisy-chain rotaxane. Furthermore, the GPC measurement of the obtained product showed that the average molecular weight was comparable to the molecular weight before neutralization, as Mn = 4970 (see Figure S4 in Supplementary Materials). In addition, the glass transition temperature of the neutralized polymer reached 3 °C, causing a further decrease in crystallinity compared to before neutralization (see Figure S5 in Supplementary Materials). This decrease suggested the involvement of the removal of interactions occurring between the secondary ammonium salt and crown ether within the [c2]daisy-chain rotaxane units. These results strongly demonstrated that the [c2]daisy-chain rotaxane significantly contributes to the structural stabilization of the polymer as a stopper.

3. Conclusions

In summary, we designed an H-G monomer in which a dibenzo-24-crown-8-ether unit and a secondary ammonium salt unit were introduced within the same molecule. We successfully achieved the one-pot synthesis of a topological polymer that remains stable without dissociation by utilizing the [c2]daisy-chain rotaxane structure. These one-pot syntheses involved the utilization of a metathesis reaction and a thiol-ene reaction. The former provided a stable polymer consisting of interconnected [c2]daisy-chain rotaxanes using only a single molecule (H-G monomer). Furthermore, the latter suggested the easy control of the solubility and crystallinity of the resulting polymer by introducing dithiol units between [c2]daisy-chain rotaxanes. Moreover, even in environments where the rotaxane structure cannot be maintained, such as polar solvents like DMSO or during neutralization processes, the resulting polymer maintained its inclusion structure without dissociation. This suggests that even when the interaction between the ammonium salt and crown ether is inhibited, the adjacent neutralized [c2]daisy-chain rotaxane functions well as a stopper and prevents the complete dissociation of their inclusion polymers. By employing this synthetic strategy, it becomes possible to conveniently synthesize various functional materials with [c2]daisy-chain rotaxane structures, contributing to a wide range of fields such as stretchable materials, stimuli-responsive materials, and self-healing materials. Currently, our focus is on material design tailored to specific applications, and we are proceeding with synthesis and evaluation.

4. Experimental Section

4.1. Materials and Instruments

Reagent-grade solvents (hexane, dichloromethane, chloroform, tetrahydrofuran (THF), acetone, methanol (MeOH), ethyl acetate (EtOAc), and dimethylformamide (DMF)) and other chemicals were used without further purification. Thin-layer chromatography was performed using MERCK (Darmstadt, Germany) 60 F254, and MERCK 60 (0.063–0.200 mm) was used as silica gel.
1H NMR (500 MHz) and 13C NMR (270 MHz) spectra were recorded on a JEOL JNM-ECA500 instrument using CDCl3 or DMSO-d6 as the deuterated solvent and tetramethyl silane (TMS) as the internal standard. Molecular weights and molecular weight distributions were estimated via gel permeation chromatography (GPC) experiments conducted on a SHIMADZU SPD-20A instrument equipped with an ultraviolet (UV) detector (257 nm) and a Shodex GPC KF-804L column (internal diameter, 8.0 mm; length, 30 cm; gel particle diameter, 7 μm; theoretical plate number >18,000). Tetrahydrofuran (CDCl3) was used as an eluent at a flow rate of 1.0 mL/min. Molecular weights were calibrated against polystyrene standards. Accurate mass measurements with electrospray ionization time-of-flight (ESI-TOF) mass were performed using a Waters Xevo(TM) G2-XS QTof. Fourier-transform infrared (FT-IR) spectra were recorded using a JASCO FTIR-6600, as well as a spectrometer. The glass transition temperature was measured using a highly sensitive differential scanning calorimeter Hitachi High-Tech Science DSC 7020.

4.2. Synthesis of Compound 1

A THF solution (200 mL) containing 3,4-Dioxa-1,8-octanediol (90.2 g, 0.599 mol), triethylamine (12.1 g, 0.120 mol), and 4-dimethylaminopyridine (DMAP) (0.146 g, 1.20 mmol) was slowly added dropwise to a THF solution (100 mL) of p-toluenesulfonic chloride (TsCl) (45.8 g, 0.240 mol). The resulting mixture was stirred at room temperature for 24 h. Subsequently, the solution was treated with saturated sodium bicarbonate solution (50 mL) and then diluted with EtOAc (300 mL). It was washed three times with water (100 mL). The organic layer obtained was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified via column chromatography using silica gel and an eluent of EtOAc. Compound 1, a colorless and transparent oil, was obtained (9.36 g, 81.9% yield). 1H NMR (500 MHz, CDCl3) δ (ppm from TMS): 7.91–7.89 (d, 2H, Ph), 7.39–7.33 (d, 2H, Ph), 4.20–4.17 (t, 2H, Ts–OCH2–), 3.80–3.58 (m, 10H, Ts–OCH2CH2–OCH2CH2–OCH2CH2–OH), 2.42 (s, 3H, CH3–Ph) (see Figure S6 in Supplementary Materials) [86].

4.3. Synthesis of Compound 2

Pyrocatechol (1.35 g, 0.0123 mol) was added to a suspension of cesium carbonate (8.01 g, 0.0246 mol) in acetonitrile (100 mL) and refluxed for 1 h. Then, the acetonitrile solution (50 mL) containing compound 1 (9.36 g, 0.0307 mol) was slowly added dropwise and refluxed for 24 h. After cooling to 25 °C, the suspension was filtered, and the filtrate was concentrated under reduced pressure. The residue was purified via column chromatography using silica gel and an eluent of EtOAc/MeOH (4/1, v/v). Compound 2, a yellow viscous oil, was obtained (9.43 g, 82.4% yield). 1H NMR (500 MHz, CDCl3) δ (ppm from TMS): 6.92 (s, 4H, Ph), 4.20–4.15 (t, 4H, Ph–OCH2–), 3.88–3.60 (m, 20H, Ph–OCH2CH2–OCH2CH2–OCH2CH2–OH) (see Figure S7 in Supplementary Materials) [87].

4.4. Synthesis of Compound 3

A THF solution (30 mL) containing compound 2 (5.88 g, 0.0175 mol), triethylamine (7.08 g, 0.0471 mol), and DMAP (0.0405 g, 0.314 mmol) was slowly added dropwise to a THF solution (20 mL) of TsCl (8.97 g, 0.0471 mol), and the mixture was stirred at 25 °C for 12 h. Then, the solution was treated with saturated sodium bicarbonate solution (50 mL) and diluted with ethyl acetate (200 mL), followed by three washes with water (100 mL). The organic layer obtained was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified via column chromatography using silica gel and an eluent of ethyl acetate/hexane (2/1, v/v). Compound 3, a yellow viscous oil, was obtained (5.76 g, 97.9% yield). 1H NMR (500 MHz, CDCl3) δ (ppm from TMS): 7.80–7.75 (d, 4H, Ph (Ts)), 7.38–7.29 (d, 4H, Ph (Ts)), 6.90 (s, 4H, Ph), 4.18–4.11 (t, 4H, Ph–OCH2–), 3.88–3.59 (m, 20H, Ph–OCH2CH2–OCH2CH2–OCH2CH2–OH), 2.44 (s, 6H, CH3–Ph) (see Figure S8 in Supplementary Materials) [87].

4.5. Synthesis of Compound 4

Compound 3 was added to a THF suspension (300 mL) of potassium carbonate (8.15 g, 25.4 mmol) and refluxed for one hour. Then, a THF solution (100 mL) of 3,4-dihydroxybenzaldehyde (0.696 g, 5.45 mmol) was added dropwise to the solution, and the mixture was refluxed for 24 h. After quenching with 1 M HCl aqueous solution, the mixture was diluted with dichloromethane (200 mL) and washed with saturated sodium chloride solution (100 mL). The organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The resulting concentrate was purified via column chromatography using silica gel and an eluent of ethyl acetate/methanol (10/1, v/v). Mono-formylated DB24C8 (compound 4), a white solid, was obtained (1.77 g, 52.9% yield). 1H NMR (500 MHz, CDCl3) δ (ppm from TMS): 9.83–9.81 (s, 1H, Ph–CHO), 7.81–7.75 (m, 5H, Ph), 7.35–7.29 (d, 2H, Ph), 4.23–4.08 (m, 24H, –CH2CH2O–) (see Figure S8 in Supplementary Materials) [87].

4.6. Synthesis of Compound 5

A THF solution (10 mL) of compound 4 was slowly added dropwise to a THF solution (10 mL) of 10-undecen-1-amine (0.720 g, 4.25 mmol), and the resulting mixture was stirred at 25 °C for 8 h. The solvent was removed under reduced pressure, yielding compound 5 with reduced formyl groups as a yellow solid (crude product, 1.31 g). It was used without further purification in the subsequent reaction. 1H NMR (500 MHz, CDCl3, crude sample) δ (ppm from TMS): 8.11–8.09 (s, 1H, Ph–CH=N), 6.88–6,80 (m, 7H, Ph), 5.82–5.73 (m, 2H, CH2=CH–), 4.98–4.87 (m, 1H, CH2=CH–), 4.21–3.78 (m, 24H, –CH2CH2O–), 3.61–3.50 (m, 2H, CH=N–CH2–), 2.03–1.90 (m, 2H, CH2=CH–CH2–), 1.73–1.67 (m, 2H, =N–CH2–CH2–), 1.37–1.20 (m, 12H, CH2=CH–(CH2)6–) (see Figure S9 in Supplementary Materials).

4.7. Synthesis of H-G Monomer

Compound 5 (1.80 g, 2.86 mmol) was dissolved in methanol (2 mL), and 1 M HCl aqueous solution (2 mL) was added dropwise. The resulting mixture was stirred at 25 °C for 1 h. MeOH was removed under reduced pressure, and the residue was diluted with dichloromethane (20 mL). The solution was washed with saturated NH4PF6 aqueous solution (10 mL × 2 times). The organic layer was concentrated under reduced pressure, and the obtained residue was washed with ethyl acetate, resulting in the white solid H-G monomer (1.00 g, 66% yield). 1H NMR (500 MHz, DMSO-d6) δ (ppm from TMS): 7.02–6.84 (m, 7H, Ph), 5.83–5.74 (m, 1H, CH2=CH–), 5.02–4.91 (m, 2H, CH2=CH–), 4.10–4.01 (m, 10H, –Ph–CH2–NH2+–, –PhO-CH2CH2O–), 3.81–3.75 (m, 8H, –PhO-CH2CH2O–), 3.66–3.63 (m, 8H, –PhO-CH2CH2O–CH2CH2O–), 2.87–2.82 (m, –Ph–CH2–NH2+–CH2–), 2.04–1.99 (m, 2H, CH2=CH–CH2–), 1.38–1.20 (m, 14H, CH2=CH–CH2–(CH2)6–). 13C NMR (270 MHz, DMSO-d6) δ (ppm from TMS): 148.96, 139.34, 125.06, 123.44, 121.69, 115.22, 70.97, 69.21, 50.36, 46.77, 40.06, 33.77, 29.06, 26.52, 19.15, 29.07 (see Figure S10 in Supplementary Materials). ESI-TOF-MS: m/z calculated for C72H110N2O16Na [M + Na]+ 652.3827; found.

4.8. Synthesis of Poly([c2]Daisy-chain Rotaxane)

To a solution of H-G monomer (0.306 g, 0.193 mmol) in chloroform (15 mL), benzylidene-bis(tricyclohexylphosphine)dichlororuthenium (Grubbs 1st, 1.00 mg, 1.22 nmol) was added; the mixed solution was stirred at 50 °C for 24 h, and then the solvent was removed under reduced pressure, followed by washing with MeOH to give a light purple solid product (0.300 g, crude product). 1H NMR (500 MHz, CDCl3, CHCl3-soluble part) δ (ppm from TMS): 6.98–6.55 (m, 14H, Ph), 5.41–5.35 (m, 2H, CH2=CH–), 4.50–4.21 (m, 4H, –Ph–CH2–NH2+–), 4.21–3.63 (m, 48H, –CH2CH2O–), 3.50–3.30 (m, 4H, –Ph–CH2–NH2+–CH2–), 2.06–1.99 (m, 4H, CH2=CH–CH2–), 1.40–1.16 (m, 28H, CH2=CH–CH2–(CH2)7–).

4.9. Synthesis of Poly([c2]Daisy-chain Rotaxane)-SH

A solution of H-G monomer (0.300 g, 0.193 mmol), 3,6-dioxa-1,8-dithiol (Dithiol) (0.0364 g, 0.199 mmol), and benzophenone (0.0035 g, 0.0193 mmol) in acetonitrile (2 mL) was subjected to UV irradiation, and the resulting mixture was reprecipitated with methanol to obtain a light-yellow solid product (0.313 g yield, crude product). 1H NMR (500 MHz, CDCl3) δ (ppm from TMS): 6.90–6.60 (m, 14H, Ph), 4.50–4.20 (d, 4H, Ph–CH2–NH2+–), 4.20–3.65 (m, 52H, –CH2CH2O–, –S–CH2–CH2–), 3.65–3.58 (d, 8H, S–CH2–CH2–O–CH2–CH2–O, CH2–CH2–S–), 3.53–3.29 (d, 4H, –Ph–CH2–NH2+–CH2–), 2.76–2.68 (m, 2H, –(CH2)10–CH2–S–), 2.58–2.36 (m, 4H, –O–CH2–CH2–S–), 1.98–1.51 (m, 2H, –O–CH2–CH2–S–CH2–CH2–), 1.40–1.15 (m, 36H, –(CH2)9–).

4.10. Synthesis of Neutralized Poly([c2]Daisy-chain Rotaxane)-SH

Poly([c2]daisy-chain rotaxane) 2 (0.107 g, 68.8 nmol) was dissolved in DMF (1 mL), and acetic anhydride (1.30 g, 12.7 mmol) was added. The mixture was stirred at 90 °C for 24 h. The resulting product was obtained as a reddish-brown oil through reprecipitation using methanol (0.0460 g yield, crude product). 1H NMR (500 MHz, CDCl3) δ (ppm from TMS): 6.90–6.55 (m, 14H, Ph), 4.50–4.30 (m, 4H, Ph–CH2–N(OCH3)–), 4.20–4.10 (m, 8H, Ph–O–CH2–CH2–O–CH2–), 3.90–3.70 (d, 16H, Ph–O–CH2–CH2–O–CH2–), 3.65–3.50 (m, 8H, –CH2–S–CH2–CH2–O–CH2–CH2–O–, CH2–CH2–S–), 3.18–3.01 (s, 4H, Ph–CH2–N(OCH3)–CH2–), 2.76–2.68 (m, 4H, –(CH2)10–CH2–S–), 2.58–2.36 (m, 4H, –O–CH2–CH2–S–), 2.03–1.98 (m, 6H, Ph–CH2–N(OCH3)–), 1.50–1.10 (m, 36H, –(CH2)10–).

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/reactions4030027/s1, Figure S1: 1H NMR spectra of H-G monomer at (A) conc. 0.1 M, (B) 0.01, and (C) 0.001 M in CDCl3; Figure S2: DSC charts of poly([c2]daisy-chain rotaxane) and poly([c2]daisy-chain rotaxane)-SH; Figure S3: IR spectra of poly([c2]daisy-chain rotaxane)-SH and neutralized poly([c2]daisy-chain rotaxane)-SH; Figure S4: GPC chart of neutralized poly([c2]Daisy-chain rotaxane (eluent: CHCl3); Figure S5: DSC charts of neutralized poly([c2]Daisy-chain rotaxane); Figures S6–S9: 1H NMR spectra of compound 1–4 in CDCl3; Figure S10: 13C NMR spectra of H-G monomer in CDCl3.

Author Contributions

Conceptualization, R.K., K.O. and K.Y.; synthesis and structural analysis, R.K.; writing—original draft preparation, K.Y. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The data presented in this study are available upon request from the corresponding author. The data are not publicly available because of the lack of a dedicated server.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Harada, A.; Kamachi, M. Complex formation between cyclodextrin and poly(propylene glycol). J. Chem. Soc. Chem. Commun. 1990, 19, 1322–1323. [Google Scholar] [CrossRef]
  2. Harada, A.; Li, J.; Kamachi, M. The molecular necklace: A rotaxane containing many threaded α-cyclodextrins. Nature 1992, 356, 325–327. [Google Scholar] [CrossRef]
  3. Harada, A.; Li, J.; Kamachi, M. Synthesis of a tubular polymer from threaded cyclodextrins. Nature 1993, 364, 516–518. [Google Scholar] [CrossRef]
  4. Harada, A.; Li, J.; Nakamitsu, T.; Kamachi, M. Preparation and characterization of polyrotaxanes containing many threaded α-cyclodextrins. J. Org. Chem. 1993, 58, 7524–7528. [Google Scholar] [CrossRef]
  5. Harada, A.; Li, J.; Kamachi, M. Preparation and Characterization of a Polyrotaxane Consisting of Monodisperse Poly(ethylene glycol) and. alpha.-Cyclodextrins. J. Am. Chem. Soc. 1994, 116, 3192–3196. [Google Scholar] [CrossRef]
  6. Harada, A.; Li, J.; Kamachi, M. Double-stranded inclusion complexes of cyclodextrin threaded on poly(ethylene glycol). Nature 1994, 370, 126–128. [Google Scholar] [CrossRef]
  7. Harada, A. Design and construction of supramolecular architectures consisting of cyclodextrins and polymers. Adv. Polym. Sci. 1997, 133, 141–191. [Google Scholar] [CrossRef]
  8. Harada, A.; Li, J.; Kamachi, M. Molecular recognition: Preparation of polyrotaxane and tubular polymer from cyclodextrin. Polym. Adv. Technol. 1997, 8, 241–249. [Google Scholar] [CrossRef]
  9. Harada, A.; Li, J.; Kamachi, M. Non-ionic [2]rotaxanes containing methylated α-cyclodextrins. Chem. Commun. 1997, 15, 1413–1414. [Google Scholar] [CrossRef]
  10. Harada, A. Construction of supramolecular structures from cyclodextrins and polymers. Carbohydr. Polym. 1997, 34, 183–188. [Google Scholar] [CrossRef]
  11. Okada, M.; Kamachi, M.; Harada, A. Preparation and Characterization of Inclusion Complexes between Methylated Cyclodextrins and Poly(tetrahydrofuran). Macromolecules 1999, 32, 7202–7207. [Google Scholar] [CrossRef]
  12. Ashton, P.R.; Grognuz, M.; Slawin, A.M.Z.; Stoddart, J.F.; Williams, D.J. The template-directed synthesis of a [2]rotaxane. Tetrahedron Lett. 1991, 32, 6235–6238. [Google Scholar] [CrossRef]
  13. Ashton, P.R.; Philp, D.; Spencer, N.; Stoddart, J.F. The self-assembly of [n]pseudorotaxanes. J. Chem. Soc. 1991, 23, 1677–1679. [Google Scholar] [CrossRef]
  14. Shen, Y.X.; Gibson, H.W. Synthesis and some properties of polyrotaxanes comprised of polyurethane backbone and crown ethers. Macromolecules 1992, 25, 2058–2059. [Google Scholar] [CrossRef]
  15. Ashton, P.R.; Philp, D.; Spencer, N.; Stoddart, J.F. A new design strategy for the self-assembly of molecular shuttles. J. Chem. Soc. 1992, 16, 1124–1128. [Google Scholar] [CrossRef]
  16. Gibson, H.W.; Marand, H. Polyrotaxanes: Molecular composites derived by physical linkage of cyclic and linear species. Adv. Mater. 1993, 5, 11–21. [Google Scholar] [CrossRef]
  17. Bissell, R.A.; Cordova, E.; Kaifer, A.E.; Stoddart, J.F. A chemically and electrochemically switchable molecular shuttle. Nature 1994, 369, 133–137. [Google Scholar] [CrossRef]
  18. Diederich, F.; Dietrich-Buchecker, C.; Nierengarten, J.; Sauvage, J.P. A copper(I)-complexed rotaxane with two fullerene stoppers. J. Chem. Soc. 1995, 7, 781–782. [Google Scholar] [CrossRef]
  19. Gibson, H.W.; Liu, S.; Lecavalier, P.; Wu, C.; Shen, Y.X. Synthesis and Preliminary Characterization of Some Polyester Rotaxanes. J. Am. Chem. Soc. 1995, 117, 852–874. [Google Scholar] [CrossRef]
  20. Ashton, P.R.; Glink, P.T.; Martinez-Diaz, M.; Stoddart, J.F.; White, A.J.P.; Williams, D.J. Thermodynamically controlled self-assembly of pseudorotaxanes and pseudopolyrotaxanes with different recognition motifs operating self-selectively. Angew. Chem. Int. Ed. 1996, 35, 1930–1933. [Google Scholar] [CrossRef]
  21. Gong, C.; Gibson, H.W. Synthesis and Characterization of a Polyester/Crown Ether Rotaxane Derived from a Difunctional Blocking Group. Macromolecules 1996, 29, 7029–7033. [Google Scholar] [CrossRef]
  22. Cao, J.; Fyfe, M.C.T.; Stoddart, J.F.; Cousins, G.R.L.; Glink, P.T. Molecular Shuttles by the Protecting Group Approach. J. Chem. Soc. 2000, 65, 1937–1946. [Google Scholar] [CrossRef] [PubMed]
  23. Kraus, T.; Budesinksy, M.; Cvacka, J.; Sauvage, J.P. Copper(I)-directed formation of a cyclic pseudorotaxane tetramer and its trimeric homologue. Angew. Chem. Int. Ed. 2006, 45, 258–261. [Google Scholar] [CrossRef] [PubMed]
  24. Nakazono, K.; Kuwata, S.; Takata, T. Crown ether–tert-ammonium salt complex fixed as rotaxane and its derivation to nonionic rotaxane. Tetrahedron Lett. 2008, 49, 2397–2401. [Google Scholar] [CrossRef]
  25. Zhu, N.; Nakazono, K.; Takata, T. Solid-state Rotaxane Switch: Synthesis of Thermoresponsive Rotaxane Shuttle Utilizing a Thermally Decomposable Acid. Chem. Lett. 2016, 45, 445–447. [Google Scholar] [CrossRef]
  26. Takata, T.; Kawasaki, H.; Asai, S.; Furusho, Y.; Kihar, N. Conjugate addition-approach to end-capping of pseudorotaxanes for rotaxane synthesis. Chem. Lett. 1999, 3, 223–224. [Google Scholar] [CrossRef]
  27. Okumura, Y.; Ito, K. The Polyrotaxane Gel: A Topological Gel by Figure-of-Eight Cross-links. Adv. Mater. 2001, 13, 485–487. [Google Scholar] [CrossRef]
  28. Oku, T.; Furusho, Y.; Takata, T. A concept for recyclable cross-linked polymers: Topologically networked polyrotaxane capable of undergoing reversible assembly and disassembly. Angew. Chem. Int. Ed. 2004, 43, 966–969. [Google Scholar] [CrossRef]
  29. Takata, T. Polyrotaxane and Polyrotaxane Network: Supramolecular Architectures Based on the Concept of Dynamic Covalent Bond Chemistry. Polym. J. 2006, 38, 1–20. [Google Scholar] [CrossRef]
  30. Yamabuki, K.; Isobe, Y.; Onimura, K.; Oishi, T. Pseudorotaxane-coupled Gel: A New Concept of Interlocked Gel Synthesis by Using Metathesis Reaction. Polym. J. 2008, 40, 205–211. [Google Scholar] [CrossRef]
  31. Zhang, Y.; Zhou, Q.; Jia, S.; Lin, K.; Fan, G.; Yuan, J.; Yu, S.; Shi, J. Specific Modification with TPGS and Drug Loading of Cyclodextrin Polyrotaxanes and the Enhanced Antitumor Activity Study In Vitro and In Vivo. ACS Appl. Mater. Interfaces 2019, 11, 46427–46436. [Google Scholar] [CrossRef] [PubMed]
  32. Takata, T. Switchable Polymer Materials Controlled by Rotaxane Macromolecular Switches. ACS Cent. Sci. 2020, 6, 129–143. [Google Scholar] [CrossRef] [PubMed]
  33. Uenuma, S.; Maeda, R.; Yokoyama, H.; Ito, K. Molecular Recognition of Fluorescent Probe Molecules with a Pseudopolyrotaxane Nanosheet. ACS Macro Lett. 2021, 10, 237–242. [Google Scholar] [CrossRef] [PubMed]
  34. Mohammed, A.F.A.; Othman, M.H.; Taharabaru, T.; Elamin, K.M.; Ito, K.; Inoue, M.; El-Badry, M.; Saleh, K.I.; Onodera, R.; Motoyama, K. Stabilization and Movable Ligand-Modification by Folate-Appended Polyrotaxanes for Systemic Delivery of siRNA Polyplex. ACS Macro Lett. 2022, 11, 1225–1229. [Google Scholar] [CrossRef]
  35. Wang, Y.; Li, Z.; Xu, H.; Wang, Q.; Peng, W.; Chi, S.; Wang, C.; Wang, J.; Deng, Y. Polymer-in-Salt Electrolyte from Poly(caprolactone)-graft-polyrotaxane for Ni-Rich Lithium Metal Batteries at Room Temperature. ACS Appl. Mater. Interfaces 2023, 15, 31552–31560. [Google Scholar] [CrossRef]
  36. Mayumi, K.; Ito, K. Structure and dynamics of polyrotaxane and slide-ring materials. Polymer 2010, 51, 959–967. [Google Scholar] [CrossRef]
  37. Hoshino, T.; Miyauchi, M.; Kawaguchi, Y.; Yamaguchi, H.; Harada, A. Daisy Chain Necklace: Tri[2]rotaxane Containing Cyclodextrins. J. Am. Chem. Soc. 2000, 122, 9876–9877. [Google Scholar] [CrossRef]
  38. Jiménez, M.C.; Dietrich-Buchecker, C.; Sauvage, J.P. Towards Synthetic Molecular Muscles: Contraction and Stretching of a Linear Rotaxane Dimer. Angew. Chem. Int. Ed. 2000, 39, 3284–3287. [Google Scholar] [CrossRef]
  39. Amirsakis, D.G.; Elizarov, A.M.; Garcia-Garibay, M.A.; Glink, P.T.; Stoddart, J.F.; White, A.J.P.; Williams, D.J. Diastereospecific Photochemical Dimerization of a Stilbene-Containing Daisy Chain Monomer in Solution as well as in the Solid State. Angew. Chem. Int. Ed. 2003, 42, 1126–1132. [Google Scholar] [CrossRef]
  40. Tsukagoshi, S.; Miyawaki, A.; Takashima, Y.; Yamaguchi, Y.; Harada, A. Contraction of Supramolecular Double-Threaded Dimer Formed by α-Cyclodextrin with a Long Alkyl Chain. Org. Lett. 2007, 9, 1053–1055. [Google Scholar] [CrossRef]
  41. Coutrot, F.; Romuald, C.; Busseron, E. A New pH-Switchable Dimannosyl[c2]Daisy Chain Molecular Machine. Org. Lett. 2008, 10, 3741–3744. [Google Scholar] [CrossRef] [PubMed]
  42. Wu, J.; Leung, K.C.F.; Bnitez, D.; Han, J.Y.; Cantrill, S.J.; Fang, L.; Stoddart, J.F. An Acid–Base-Controllable [c2]Daisy Chain. Angew. Chem. Int. Ed. 2008, 47, 7470–7474. [Google Scholar] [CrossRef] [PubMed]
  43. Romuald, C.; Busseron, E.; Coutrot, F. Very Contracted to Extended co-Conformations with or without Oscillations in Two- and Three-Station [c2]Daisy Chains. J. Org. Chem. 2010, 75, 6516–6531. [Google Scholar] [CrossRef] [PubMed]
  44. Zheng, B.; Klautzsch, F.; Xue, M.; Huang, F.; Schalley, C.A. Self-sorting of crown ether/secondary ammonium ion hetero-[c2]daisy chain pseudorotaxanes. Org. Chem. Front. 2014, 1, 532–540. [Google Scholar] [CrossRef]
  45. Bruns, C.J.; Stoddart, J.F. Rotaxane-Based Molecular Muscles. Acc. Chem. Res. 2014, 47, 2186–2199. [Google Scholar] [CrossRef]
  46. Wolf, A.; Moulin, E.; Cid, J.J.; Goujon, A.; Du, G.; Busseron, E.; Fuks, G.; Giuseppone, N. pH and light-controlled self-assembly of bistable [c2] daisy chain rotaxanes. Chem. Commun. 2015, 51, 4212–4215. [Google Scholar] [CrossRef]
  47. Goujon, A.; Du, G.; Moulin, E.; Fuks, G.; Maaloum, M.; Buhler, E.; Giuseppone, N. Hierarchical Self-Assembly of Supramolecular Muscle-Like Fibers. Angew. Chem. 2015, 55, 703–707. [Google Scholar] [CrossRef]
  48. Fu, X.; Zhang, Q.; Rao, S.J.; Qu, D.H.; Tian, H. One-pot synthesis of a [c2]daisy-chain-containing hetero[4]rotaxane via a self-sorting strategy. Chem. Sci. 2016, 7, 1696–1701. [Google Scholar] [CrossRef]
  49. Wang, P.; Gao, Z.; Yuan, M.; Zhu, J.; Wang, F. Mechanically linked poly[2]rotaxanes constructed from the benzo-21-crown-7/secondary ammonium salt recognition motif. Polym. Chem. 2016, 7, 3664–3668. [Google Scholar] [CrossRef]
  50. Aoki, D.; Aibara, G.; Uchida, S.; Takata, T. A Rational Entry to Cyclic Polymers via Selective Cyclization by Self-Assembly and Topology Transformation of Linear Polymers. J. Am. Chem. Soc. 2017, 139, 6791–6794. [Google Scholar] [CrossRef]
  51. Zhang, Q.; Rao, S.; Xie, T.; Li, X.; Xu, T.; Li, D.; Qu, D.; Long, Y.; Tian, H. Muscle-like Artificial Molecular Actuators for Nanoparticles. Chem 2018, 4, 2670–2684. [Google Scholar] [CrossRef]
  52. Rao, S.J.; Ye, X.H.; Zhang, Q.; Gao, C.; Wang, W.Z.; Qu, D.H. Light-Induced Cyclization of A [c2]Daisy-Chain Rotaxane to Form a Shrinkable Double-Lasso Macrocycle. Asian J. Org. Chem. 2018, 7, 902–905. [Google Scholar] [CrossRef]
  53. Wolf, A.; Cid, J.-J.; Moulin, E.; Niess, F.; Du, G.; Goujon, A.; Busseron, E.; Ruff, A.; Ludwigs, S.; Giuseppone, N. Unsymmetric Bistable [c2]Daisy Chain Rotaxanes which Combine Two Types of Electroactive Stoppers. Eur. J. Org. Chem. 2019, 2019, 3421–3432. [Google Scholar] [CrossRef]
  54. Van Raden, J.M.; Jarenwattananon, N.N.; Zakharov, L.N.; Jasti, R. Active Metal Template Synthesis and Characterization of a Nanohoop [c2]Daisy Chain Rotaxane. Chem. Eur. J. 2020, 26, 10205–10209. [Google Scholar] [CrossRef] [PubMed]
  55. Cai, K.; Shi, Y.; Zhuang, G.; Zhang, L.; Qiu, Y.; Shen, D.; Chen, H.; Jiao, Y.; Wu, H.; Cheng, C.; et al. Molecular-Pump-Enabled Synthesis of a Daisy Chain Polymer. J. Am. Chem. Soc. 2020, 142, 10308–10313. [Google Scholar] [CrossRef] [PubMed]
  56. Schroder, H.V.; Zhang, Y.; Link, A.J. Dynamic covalent self-assembly of mechanically interlocked molecules solely made from peptides. Nat. Chem. 2021, 13, 850–857. [Google Scholar] [CrossRef] [PubMed]
  57. Tsuda, S.; Komai, Y.; Fujiwara, S.; Nishiyama, Y. Cyclodextrin-Based [c2]Daisy Chain Rotaxane Insulating Two Diarylacetylene Cores. Chem. Eur. J. 2021, 27, 1966–1969. [Google Scholar] [CrossRef]
  58. Chu, C.; Stares, D.L.; Schalley, C.A. Light-controlled interconversion between a [c2]daisy chain and a lasso-type pseudo[1]rotaxane. Chem. Commun. 2021, 57, 12317–12320. [Google Scholar] [CrossRef]
  59. Nhien, P.Q.; Tien, J.H.; Cuc, T.T.K.; Khang, T.M.; Trung, N.T.; Wu, C.H.; Hue, B.T.B.; Judy, I.W.; Lin, H.C. Reversible fluorescence and Forster resonance energy transfer switching behaviours of bistable photo-switchable [c2] daisy chain rotaxanes and photo-patterning applications. J. Mater. Chem. C 2022, 10, 18241–18257. [Google Scholar] [CrossRef]
  60. Saura-Sanmartin, A.; Pastor, A.; Martinez-Cuezva, A.; Berna, J. Maximizing the [c2]daisy chain to lasso ratio through competitive self-templating clipping reactions. Chem. Commun. 2022, 58, 290–293. [Google Scholar] [CrossRef]
  61. Trung, N.T.; Nhien, P.Q.; Kim Cuc, T.T.; Wu, C.; Buu Hue, B.T.; Wu, J.I.; Li, Y.; Lin, H. Controllable Aggregation-Induced Emission and Förster Resonance Energy Transfer Behaviors of Bistable [c2]Daisy Chain Rotaxanes for White-Light Emission and Temperature-Sensing Applications. ACS Appl. Mater. Interfaces 2023, 15, 15353–15366. [Google Scholar] [CrossRef] [PubMed]
  62. Saura-Sanmartin, A.; Schalley, C.A. The Mobility of Homomeric Lasso- and Daisy Chain-Like Rotaxanes in Solution and in the Gas Phase as a means to Study Structure and Switching Behaviour. Isr. J. Chem. 2023, 63, e202300022. [Google Scholar] [CrossRef]
  63. Clark, P.G.; Day, M.W.; Grubbs, R.H. Switching and Extension of a [c2]Daisy-Chain Dimer Polymer. J. Am. Chem. Soc. 2009, 131, 13631–13633. [Google Scholar] [CrossRef] [PubMed]
  64. Du, G.; Moulin, E.; Jouault, N.; Buhler, E.; Giuseppone, N. Muscle-like Supramolecular Polymers: Integrated Motion from Thousands of Molecular Machines. Angew. Chem. 2012, 51, 12504–12508. [Google Scholar] [CrossRef] [PubMed]
  65. Gao, L.; Zhang, Z.; Zheng, B.; Huang, F. Construction of muscle-like metallo-supramolecular polymers from a pillar[5]arene-based [c2]daisy chain. Polym. Chem. 2014, 5, 5734–5739. [Google Scholar] [CrossRef]
  66. Fu, X.; Gu, R.R.; Zhang, Q.; Rao, S.J.; Zheng, X.L.; Qu, D.H.; Tian, H. Phototriggered supramolecular polymerization of a [c2]daisy chain rotaxane. Polym. Chem. 2016, 7, 2166–2170. [Google Scholar] [CrossRef]
  67. Goujon, A.; Mariani, G.; Lang, T.; Moulin, E.; Rawiso, M.; Buhler, E.; Giuseppone, E. Controlled Sol–Gel Transitions by Actuating Molecular Machine Based Supramolecular Polymers. J. Am. Chem. Soc. 2017, 139, 4923–4928. [Google Scholar] [CrossRef]
  68. Goujon, A.; Lang, T.; Mariani, G.; Moulin, E.; Fuks, G.; Raya, J.; Buhler, E.; Giuseppone, N. Bistable [c2] Daisy Chain Rotaxanes as Reversible Muscle-like Actuators in Mechanically Active Gel. J. Am. Chem. Soc. 2017, 139, 14825–14828. [Google Scholar] [CrossRef]
  69. Goujon, A.; Moulin, E.; Fuks, G.; Giuseppone, N. [c2]Daisy chain rotaxanes as molecular muscles. CCS Chem. 2019, 1, 83–96. [Google Scholar] [CrossRef]
  70. Zhang, Z.; You, W.; Li, P.; Zhao, J.; Guo, Z.; Xu, T.; Chen, J.; Yu, W.; Yan, X. Insights into the Correlation of Microscopic Motions of [c2]Daisy Chains with Macroscopic Mechanical Performance for Mechanically Interlocked Networks. J. Am. Chem. Soc. 2023, 145, 567–578. [Google Scholar] [CrossRef]
  71. Hmadeh, M.; Fang, L.; Trabolsi, A.; Elhabiri, M.; Albrecht-Gary, A.M.; Stoddart, J.F. On the thermodynamic and kinetic investigations of a [c2]daisy chain polymer. J. Mater. Chem. 2010, 20, 3422–3430. [Google Scholar] [CrossRef]
  72. Fu, G.C.; Nguyen, S.T.; Grubbs, R.H. Catalytic ring-closing metathesis of functionalized dienes by a ruthenium carbene complex. J. Am. Chem. Soc. 1993, 115, 9856–9857. [Google Scholar] [CrossRef]
  73. Fox, H.H.; Schrock, R.R.; O’Dell, R. Coupling of Terminal Olefins by Molybdenum(VI) Imido Alkylidene Complexes. Organometallics 1994, 13, 635–639. [Google Scholar] [CrossRef]
  74. Miller, S.J.; Grubbs, R.H. Synthesis of Conformationally Restricted Amino Acids and Peptides Employing Olefin Metathesis. J. Am. Chem. Soc. 1995, 117, 5855–5856. [Google Scholar] [CrossRef]
  75. Hoveyda, A.H.; Zhugralin, A.R. The remarkable metal-catalysed olefin metathesis reaction. Nature 2007, 450, 243–251. [Google Scholar] [CrossRef]
  76. Kumaraswamy, G.; Sadaiah, K.; Ramakrishna, D.S.; Police, N.; Sridhar, B.; Bharatam, J. Highly enantioselective carbon-carbon bond formation by Cu-catalyzed asymmetric [2,3]-sigmatropic rearrangement: Application to the syntheses of seven-membered oxacycles and six-membered carbocycles. Chem. Commun. 2008, 42, 5324–5326. [Google Scholar] [CrossRef]
  77. Reddy, K.K.S.; Rao, B.V.; Raju, S.S. A common approach to pyrrolizidine and indolizidine alkaloids; formal synthesis of (-)-isoretronecanol, (-)-trachelanthamidine and an approach to the synthesis of (-)-5-epitashiromine and (-)-tashiromine. Tetrahedron Asymmetry 2011, 22, 662–668. [Google Scholar] [CrossRef]
  78. Rao, G.B.D.; Anjaneyulu, B.; Kaushik, M.P. Greener and expeditious one-pot synthesis of dihydropyrimidinone derivatives using non-commercial β-ketoesters via the Biginelli reaction. RSC Adv. 2014, 4, 43321–43325. [Google Scholar] [CrossRef]
  79. Rao, G.B.D.; Anjaneyulu, B.; Kaushik, M.P. A facile one-pot five-component synthesis of glycoside annulated dihydropyrimidinone derivatives with 1,2,3-triazol linkage via transesterification/Biginelli/click reactions in aqueous medium. Tetrahedron Lett. 2014, 55, 19–22. [Google Scholar] [CrossRef]
  80. Bendi, A.; Rao, G.B.D. Strategic One-pot Synthesis of Glycosyl Annulated Phosphorylated/Thiophosphorylated 1,2,3-Triazole Derivatives Using CuFe2O4 Nanoparticles as Heterogeneous Catalyst, their DFT and Molecular Docking Studies as Triazole Fungicides. Lett. Org. Chem. 2023, 20, 568–578. [Google Scholar] [CrossRef]
  81. Okay, O.; Reddy, S.K.; Bowman, C.N. Molecular Weight Development during Thiol-Ene Photopolymerizations. Macromolecules 2005, 38, 4501–4511. [Google Scholar] [CrossRef]
  82. Sumerlin, B.S.; Vogt, A.P. Macromolecular Engineering through Click Chemistry and Other Efficient Transformations. Macromolecules 2010, 43, 1–13. [Google Scholar] [CrossRef]
  83. Mazzolini, J.; Boyron, O.; Monteil, V.; Gigmes, D.; Bertin, D.; D’Agosto, F.; Boisson, C. Polyethylene End Functionalization Using Radical-Mediated Thiol-Ene Chemistry: Use of Polyethylenes Containing Alkene End Functionality. Macromolecules 2011, 44, 3381–3387. [Google Scholar] [CrossRef]
  84. Yokochi, H.; Ohira, M.; Oka, M.; Honda, S.; Li, X.; Aoki, D.; Otsuka, H. Topology Transformation toward Cyclic, Figure-Eight-Shaped, and Cross-Linked Polymers Based on the Dynamic Behavior of a Bis(hindered amino)disulfide Linker. Macromolecules 2021, 54, 9992–10000. [Google Scholar] [CrossRef]
  85. Nomura, T.; Onimura, K.; Yamabuki, K. Synthesis and Polymerization of Acid-degradable Rotaxane Using Boc Protecting Group. Chem. Lett. 2022, 51, 16–19. [Google Scholar] [CrossRef]
  86. Moeller, N.; Ruehling, A.; Lamping, S.; Hellwig, T.; Fallnich, C.; Ravoo, B.J.; Glorius, F. Stabilization of High Oxidation State Upconversion Nanoparticles by N-Heterocyclic Carbenes. Angew. Chem. Int. Ed. 2017, 56, 4356–4360. [Google Scholar] [CrossRef]
  87. Liu, D.; Wang, D.; Wang, M.; Zheng, Y.; Koynov, K.; Auernhammer, G.K.; Butt, H.; Ikeda, T. Supramolecular Organogel Based on Crown Ether and Secondary Ammoniumion Functionalized Glycidyl Triazole Polymers. Macromolecules 2013, 46, 4617–4625. [Google Scholar] [CrossRef]
Reactions 04 00027 g001
Figure 1. Conventional synthesis method of “rotaxane” and applications of functional rotaxane materials (ex. slide-ring gel).
Figure 1. Conventional synthesis method of “rotaxane” and applications of functional rotaxane materials (ex. slide-ring gel).
Reactions 04 00027 g001
Reactions 04 00027 g002
Figure 2. One-pot synthesis of “poly([c2]daisy-chain rotaxane)” with a pseudo-stopper.
Figure 2. One-pot synthesis of “poly([c2]daisy-chain rotaxane)” with a pseudo-stopper.
Reactions 04 00027 g002
Reactions 04 00027 sch001
Scheme 1. Synthesis of “H-G monomer”.
Scheme 1. Synthesis of “H-G monomer”.
Reactions 04 00027 sch001
Reactions 04 00027 g003
Figure 3. 1H NMR spectra of H-G monomer in (A) DMSO-d6 and (B) CDCl3.
Figure 3. 1H NMR spectra of H-G monomer in (A) DMSO-d6 and (B) CDCl3.
Reactions 04 00027 g003
Reactions 04 00027 sch002
Scheme 2. One-pot synthesis of poly([c2]daisy-chain rotaxane) by using metathesis reaction.
Scheme 2. One-pot synthesis of poly([c2]daisy-chain rotaxane) by using metathesis reaction.
Reactions 04 00027 sch002
Reactions 04 00027 g004
Figure 4. 1H NMR spectra of poly([c2]daisy-chain rotaxane) in (A) CDCl3 and (B) DMSO-d6.
Figure 4. 1H NMR spectra of poly([c2]daisy-chain rotaxane) in (A) CDCl3 and (B) DMSO-d6.
Reactions 04 00027 g004
Reactions 04 00027 g005
Figure 5. GPC chart of poly([c2]daisy-chain rotaxane) (eluent: CHCl3).
Figure 5. GPC chart of poly([c2]daisy-chain rotaxane) (eluent: CHCl3).
Reactions 04 00027 g005
Reactions 04 00027 sch003
Scheme 3. One-pot synthesis of poly([c2]daisy-chain rotaxane)-SH by using thiol-ene reaction.
Scheme 3. One-pot synthesis of poly([c2]daisy-chain rotaxane)-SH by using thiol-ene reaction.
Reactions 04 00027 sch003
Reactions 04 00027 g006
Figure 6. 1H NMR spectrum of poly([c2]daisy-chain rotaxane)-SH in CDCl3.
Figure 6. 1H NMR spectrum of poly([c2]daisy-chain rotaxane)-SH in CDCl3.
Reactions 04 00027 g006
Reactions 04 00027 g007
Figure 7. GPC chart of poly([c2]daisy-chain rotaxane) (eluent: CHCl3).
Figure 7. GPC chart of poly([c2]daisy-chain rotaxane) (eluent: CHCl3).
Reactions 04 00027 g007
Reactions 04 00027 sch004
Scheme 4. Neutralization of poly([c2]daisy-chain rotaxane)-SH with acetic anhydride.
Scheme 4. Neutralization of poly([c2]daisy-chain rotaxane)-SH with acetic anhydride.
Reactions 04 00027 sch004
Reactions 04 00027 g008
Figure 8. 1H NMR spectrum of neutralized poly([c2]daisy-chain rotaxane)-SH in CDCl3.
Figure 8. 1H NMR spectrum of neutralized poly([c2]daisy-chain rotaxane)-SH in CDCl3.
Reactions 04 00027 g008
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Kamoto, R.; Onimura, K.; Yamabuki, K. One-Pot Synthesis of Stable Poly([c2]Daisy–chain Rotaxane) with Pseudo-Stopper via Metathesis Reaction and Thiol-Ene Reaction. Reactions 2023, 4, 448-464. https://doi.org/10.3390/reactions4030027

AMA Style

Kamoto R, Onimura K, Yamabuki K. One-Pot Synthesis of Stable Poly([c2]Daisy–chain Rotaxane) with Pseudo-Stopper via Metathesis Reaction and Thiol-Ene Reaction. Reactions. 2023; 4(3):448-464. https://doi.org/10.3390/reactions4030027

Chicago/Turabian Style

Kamoto, Risako, Kenjiro Onimura, and Kazuhiro Yamabuki. 2023. "One-Pot Synthesis of Stable Poly([c2]Daisy–chain Rotaxane) with Pseudo-Stopper via Metathesis Reaction and Thiol-Ene Reaction" Reactions 4, no. 3: 448-464. https://doi.org/10.3390/reactions4030027

APA Style

Kamoto, R., Onimura, K., & Yamabuki, K. (2023). One-Pot Synthesis of Stable Poly([c2]Daisy–chain Rotaxane) with Pseudo-Stopper via Metathesis Reaction and Thiol-Ene Reaction. Reactions, 4(3), 448-464. https://doi.org/10.3390/reactions4030027

Article Metrics

Back to TopTop