Skip to main content
NCBI home page
Frontiers in Chemistry logoLink to Frontiers in Chemistry
. 2020 Nov 19;8:610093. doi: 10.3389/fchem.2020.610093

Supramolecular Polymers With AIE Property Fabricated From a Cyanostilbene Motif-Derived Ditopic Benzo-21-Crown-7 and a Ditopic Dialkylammonium Salt

Haoran Wu 1, Tangxin Xiao 1,*
PMCID: PMC7710702  PMID: 33330405

Abstract

Fluorescent supramolecular polymers (FSP) have attracted considerable attention in recent years. Particularly, the incorporation of aggregation-induced emission (AIE) property to the FSP will bring this material into practical applications. Herein, we designed and synthesized a cyanostilbene motif derived ditopic benzo-21-crown-7 (B21C7) as a host molecule (H). The cyanostilbene motif endows H with AIE property while the B21C7 motif renders it with the capability to complex with electron deficient guest molecules. Upon the addition of a ditopic dialkylammonium salt molecule (G), a novel FSP with blue luminescent property can be constructed. This B21C7-based host-guest FSP with blue fluorescence may have potential application in supramolecular luminescent materials.

Keywords: supramolecular polymer, AIE, host-guest, fluorescent materials, B21C7

Introduction

Supramolecular polymers, in which ordered and highly directional polymeric arrays of monomeric building blocks are brought together by reversible non-covalent bonds, are outstanding materials that generally exhibit stimuli-responsive and self-healing properties (Aida et al., 2012; Yang et al., 2015; Wehner and Würthner, 2020). The driving force of supramolecular polymers usually includes hydrogen bonds (Xiao et al., 2019b,e; Datta et al., 2020; Qi et al., 2020), metal-ligand bonds (Zheng et al., 2016; Shi et al., 2019), host-guest complexation (Guo et al., 2010; Harada et al., 2014; Wang et al., 2018; Xiao and Wang, 2018; Xiao et al., 2018, 2019d; Chen et al., 2019), donor–acceptor interaction (Han et al., 2018), π-π stacking (Wagner et al., 2019; Xiao et al., 2019c), or a combination of them (Li et al., 2012; Wei et al., 2015; Xiao et al., 2020b). In recent years, supramolecular fluorescent materials have drawn much attention, such as fluorescent molecular switches (Cheng et al., 2017), fluorescent sensors (Kumawat et al., 2019), fluorescent metallaclip (Wang et al., 2019), and artificial light-harvesting systems (Xiao et al., 2019g, 2020a). Particularly, the development of fluorescent supramolecular polymers (FSPs) has attracted more and more interest because of their potential application in the area of dynamic luminescent materials (Ji et al., 2013; Zhang et al., 2017, 2018; Li et al., 2019). Moreover, the emergence of aggregation-induced emission (Hong et al., 2011) (AIE) fluorophores laid the foundation for the application of FSP in practice.

Macrocycle-based host-guest interaction is an important driving force in supramolecular chemistry. For example, we have reviewed a series of supramolecular materials based on pillararene (Xiao et al., 2019a,f,h). Benzo-21-crown-7 (B21C7) is one of the most important crown ethers (Zhang et al., 2007), and it shows interesting applications like adhesive materials (Dong et al., 2017; Zhang et al., 2019). B21C7 is the smallest crown ether that can complex with dialkylammonium salts, leading to a relatively strong host-guest interaction. Cyanostilbene is a well-known fluorophore and shows interesting AIE behavior, which is usually used for the construction of rotaxanes (Lee et al., 2013), nanoparticles with near-infrared emission (Shi et al., 2016), hydrogen-bonded supramolecular polymer (Lavrenova et al., 2017), and light-harvesting system (Kim et al., 2018; Sun et al., 2020). To the best of our knowledge, the integration of B21C7 unit and cyanostilbene unit to a host molecule to construct FSP has not yet been reported so far.

Previously, we have reported some orthogonal supramolecular polymers based on B21C7 (Xiao et al., 2013, 2020c). Herein, we designed and synthesized a new host molecule H, which bears both cyanostilbene motif and B21C7 units (Figure 1). The cyanostilbene motif endows H with the property of AIE, while B21C7 unit endows H with the capability to bind dialkylammonium salt. In the presence of guest molecule G (a ditopic dialkylammonium salt compound), a novel AA/BB-type FSP can be fabricated by crown ether-based host-guest complexation. Furthermore, the FSP could be assembled into macroscopic fibers with blue fluorescence from concentrated solution. This crown ether-based FSP with beautiful blue fluorescence both in solution and in the solid state may have potential application in supramolecular luminescent materials.

Figure 1.

Figure 1

Open in a new tab

Schematic illustration of the AIE supramolecular polymer constructed from H and G.

Results and Discussions

Synthesis

The synthesis of organic molecules H and G are straightforward. Compound H was synthesized from B21C7-based derivative A (Lu et al., 2018) and cyanostilbene-derived compound 5 (Scheme 1). As shown in Scheme 1, starting from p-anisaldehyde and 4-methoxybenzyl cyanide, compound 4 was prepared in ethanol solution by condensation reaction. Demethylation of compound 4 with boron tribromide in dichloromethane (DCM) yields compound 5 (Gu et al., 2012). Compound G was synthesized according to literature report (Li et al., 2018). The compounds that have not been reported previously are carefully characterized by 1H NMR, 13C NMR, and HR-MS (Supplementary Figures 1–4).

Scheme 1.

Scheme 1

Open in a new tab

Synthetic route of compound H.

AIE and Vapochromic Behavior of H

In order to examine whether the cyanostilbene motif bridged B21C7 is AIE active, the fluorescence spectra of H in mixed H2O/Tetrahydrofuran (THF) solutions were investigated. As shown in Figure 2, H shows an obvious AIE behavior. There is no fluorescence emission when H was in pure THF (a good solvent for H). When water (a poor solvent for H) content was increased gradually to 80%, a moderate emission was observed. The absorption spectrum of H is shown in Supplementary Figure 5. The emission wavelength was at 480 nm when exited at 365 nm. Upon increasing water content to 95%, the fluorescence intensity of H exhibits a dramatic enhancement with a bright blue color. The dried powder of H was obtained as a light yellow solid, which exhibited intense blue luminescence under irradiation at 365 nm at room temperature (Figure 2B). Interestingly, exposing the sample to DCM vapor resulted in a distinct change of color from blue to green within only 30 s (Figure 2B). Notably, the blue color can be recovered by heating the sample to remove the DCM (Figure 2B).

Figure 2.

Figure 2

Open in a new tab

(A) Fluorescence emission spectra of H versus H2O fraction in THF/H2O mixtures (λex = 365 nm, [H] = 5 × 10−5 M). Inset: photographs of H in THF and H in THF/H2O = 5: 95 mixtures ([H] = 5 × 10−5 M); and (B) solid powder of H under natural light (i) and UV light (ii), fumigation with DCM (iii), and color recovered by heating (iv).

Supramolecular Polymerization Studied by 1H NMR and Viscometry

Supramolecular polymerization of H and G was first investigated by concentration-dependent 1H NMR. It was measured in mixed CDCl3/CD3CN (1:1, v/v) at concentrations in the range of 2–64 mM (Figure 3). The concentration-dependent 1H NMR spectra showed a complex picture owing to the slow-exchange complexation of the B21C7 motif with the dialkylammonium salt on the NMR timescale. It should be noted that the peak splitting is relatively sharp at low concentrations (2–8 mM), suggesting that the cyclic oligomers are predominant species at this stage. As the concentration increases, these peaks became broad, indicating the formation of high-molecular-weight assemblies, such as supramolecular polymers. By contrast, the concentration-dependent 1H NMR spectra of individual H shows no chemical shift change upon concentration increasing (Supplementary Figure 6).

Figure 3.

Figure 3

Open in a new tab

1H NMR spectra (300 MHz, CDCl3/CD3CN = 1/1, v/v, 298 K) of individual H and G, and mixtures of them at different monomer concentrations ([H]/[G] = 1/1).

To further study the supramolecular polymerization driven by crown ether-based host-guest interaction, viscosity measurements were performed by using a micro-Ubbelohde viscometer. A double logarithmic curve of specific viscosity toward monomer concentration is depicted in Figure 4. During the low concentration range, the slope value was tested to be 1.04, which is the characteristic of cyclic oligomers with constant size. When the concentration increased to 9 mM, a steeper curve with a slope 1.84 was obtained, suggesting that the cyclic oligomers are gradually transformed into supramolecular polymers. This phenomenon was in line with concentration-dependent 1H NMR.

Figure 4.

Figure 4

Open in a new tab

Specific viscosity of H/G complex vs. the monomer concentration in CDCl3/CH3CN (1:1, v/v) solutions (298 K).

Solid-State Fluorescence Spectroscopy

The formation of supramolecular polymers was further evidenced by its processibility. Fibers can be drawn from a concentrated solution of the host and guest with a molar ratio of H/G = 1/1 (Figure 5A). Such fibers can be only made from entanglements of large aggregates. By contrast, no fiber can be pulled out from the concentrated solution of individual H or individual G. The fiber is colorless under visible light (Figure 5A) and generates blue fluorescence under UV light (Figure 5B). This fiber still has fluorescent luminescence after preparation for several days, indicating that the supramolecular polymer has potential applications in the area of supramolecular luminescent materials. The photophysical property of the supramolecular polymer was further investigated by solid-state fluorescence spectroscopy. As shown in Figure 5C, the emission wavelength of H shows a hypochromic shift from 480 nm in solution to 415 nm in the solid state. Compared with individual H, the supramolecular polymer in the solid state exhibited a stronger emission and bathochromic shift to 430 nm, indicating that the incorporation of the guest affected the packing of the fluorophores in the solid state, resulting in modified luminescent properties.

Figure 5.

Figure 5

Open in a new tab

(A) A rod-like fiber formed from H and G under visible light; (B) the rod-like fiber under UV (365 nm) lamp irradiation; and (C) fluorescence spectra of H and H-G in the solid state, λex = 365 nm.

Experimental

General

All chemicals, reagents, and solvents were purchased from commercial suppliers and used, unless otherwise stated, without further purification. If needed, solvents were dried by literature-known procedures. All yields were given as isolated yields. The 1H NMR and 13C NMR spectra were recorded with a Bruker AVANCE III (300 MHz) spectrometer and calibrated against the residual proton signal or natural abundance carbon resonance of the used deuterated solvent from tetramethylsilane as the internal standard. The chemical shifts δ are indicated in ppm and the coupling constants J in Hz. The multiplicities are given as s (singlet), d (doublet), dd (doublet of doublets), t (triplet), and m (multiplet). High-resolution electrospray ionization mass spectra (HR-ESI-MS) were recorded on an Agilent Technologies 6540 UHD Accurate-Mass. Fluorescence measurements were performed on an Agilent Cary Eclipse spectrofluorometer. Viscosity measurements were carried out with Ubbelohde microviscometers (Shanghai Liangjing Glass Instrument Factory, 0.40 mm inner diameter) at 298 K in chloroform and acetonitrile.

Synthesis of Compound H

To a solution of compound 5 (237 mg, 1.0 mmol) in THF (15 mL) was added compound A (1.26 g, 3.0 mmol) and 4-dimethylaminopyridine (18 mg, 0.15 mmol) at room temperature under N2 atmosphere. Then the Et3N (303 mg, 3.0 mmol) was added with vigorous stirred over 15 min. The reaction mixture was heated at 70°C for 2 h and then poured into water (100 mL). The resulting mixture was extracted with DCM (50 mL × 3) and the combined extracts were washed with H2O (100 mL × 3), brine (50 mL × 3), dried over anhydrous Na2SO4 and concentrated under reduced pressure. The resulting residue was chromatographed over silica gel (DCM:MeOH = 60:1, v/v) to afford compound H as a light yellow solid (460 mg, 0.46 mmol), yield: 46%. 1H NMR (300 MHz, CDCl3): δ (ppm) = 7.98 (d, J = 9.0 Hz, 2H, ArH), 7.85 (dd, J = 8.4, 2.1 Hz, 2H, ArH), 7.74 (d, J = 8.7 Hz, 2H, ArH), 7.69 (d, J = 1.8 Hz, 2H, ArH), 7.54 (s, 1H, alkene-H), 7.32 (m, 4H, ArH), 6.96 (d, J = 8.7 Hz, 2H, ArH), 4.33–4.19 (m, 8H, -OCH2CH2O-), 4.03–3.93 (m, 8H, -OCH2CH2O-), 3.82 (m, 8H, -OCH2CH2O-), 3.76 (m, 8H, -OCH2CH2O-), 3.69 (s, 16H, -OCH2CH2O-). 13C NMR (75 MHz, CDCl3): δ (ppm) = 164.6, 164.5, 153.7, 153.7, 152.6, 151.8, 148.5, 141.2, 132.0, 131.2, 130.6, 127.2, 124.9, 124.8, 122.6, 122.5, 121.7, 121.6, 117.9, 114.9, 112.3, 110.8, 71.4, 71.3, 71.2, 71.1, 71.0, 71.0, 70.6, 69.6, 69.5, 69.4, 69.2. HR-ESI-MS: m/z calcd for [C53H64NO18]+ = 1002.4118, found = 1002.4120.

Conclusion

In summary, we have successfully synthesized a cyanostilbene motif bridged ditopic B21C7 compound, which exhibits good AIE property and vapochromic behavior. Supramolecular polymers can be fabricated by such a host compound with a ditopic dialkylammonium salt guest. The host-guest supramolecular polymerization was fully characterized by concentration-dependent 1H NMR, viscosity measurements, and fiber formation test. Fluorescent properties of the supramolecular polymers in the solid state are also studied, which suggests that the supramolecular polymers can enhance the AIE of the individual host. The FSP described in this work may have potential applications in the field of dynamic luminescent materials.

Data Availability Statement

The original contributions generated for the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author/s.

Author Contributions

TX conceived and designed the study and wrote and revised the manuscript. HW conducted the synthetic experiments. All authors analyzed and interpreted the data.

Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Acknowledgments

We gratefully thank the financial support from the National Natural Science Foundation of China (21702020).

Supplementary Material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fchem.2020.610093/full#supplementary-material

Click here for additional data file. (4.8MB, DOCX)

References

  1. Aida T., Meijer E. W., Stupp S. I. (2012). Functional supramolecular polymers. Science 335, 813–817. 10.1126/science.1205962 [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Chen Y., Sun S., Lu D., Shi Y., Yao Y. (2019). Water-soluble supramolecular polymers constructed by macrocycle-based host-guest interactions. Chin. Chem. Lett. 30, 37–43. 10.1016/j.cclet.2018.10.022 [DOI] [Google Scholar]
  3. Cheng M., Zhang J., Ren X., Guo S., Xiao T., Hu X. Y., et al. (2017). Acid/base-controllable fluorescent molecular switches based on cryptands and basic N-heteroaromatics. Chem. Commun. 53, 11838–11841. 10.1039/C7CC07469G [DOI] [PubMed] [Google Scholar]
  4. Datta S., Kato Y., Higashiharaguchi S., Aratsu K., Isobe A., Saito T., et al. (2020). Self-assembled poly-catenanes from supramolecular toroidal building blocks. Nature 583, 400–405. 10.1038/s41586-020-2445-z [DOI] [PubMed] [Google Scholar]
  5. Dong S., Leng J., Feng Y., Liu M., Stackhouse C. J., Schonhals A., et al. (2017). Structural water as an essential comonomer in supramolecular polymerization. Sci. Adv. 3:eaao0900. 10.1126/sciadv.aao0900 [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Gu X., Yao J., Zhang G., Yan Y., Zhang C., Peng Q., et al. (2012). Polymorphism-dependent emission for di(p-methoxylphenyl)dibenzofulvene and analogues: optical waveguide/amplified spontaneous emission behaviors. Adv. Funct. Mater. 22, 4862–4872. 10.1002/adfm.201201482 [DOI] [Google Scholar]
  7. Guo D.-S., Chen S., Qian H., Zhang H.-Q., Liu Y. (2010). Electrochemical stimulus-responsive supramolecular polymer based on sulfonatocalixarene and viologen dimers. Chem. Commun. 46, 2620–2622. 10.1039/b925157j [DOI] [PubMed] [Google Scholar]
  8. Han Y., Tian Y., Li Z., Wang F. (2018). Donor-acceptor-type supramolecular polymers on the basis of preorganized molecular tweezers/guest complexation. Chem. Soc. Rev. 47, 5165–5176. 10.1039/C7CS00802C [DOI] [PubMed] [Google Scholar]
  9. Harada A., Takashima Y., Nakahata M. (2014). Supramolecular polymeric materials via cyclodextrin-guest interactions. Acc. Chem. Res. 47, 2128–2140. 10.1021/ar500109h [DOI] [PubMed] [Google Scholar]
  10. Hong Y., Lam J. W. Y., Tang B. Z. (2011). Aggregation-induced emission. Chem. Soc. Rev. 40, 5361–5388. 10.1039/c1cs15113d [DOI] [PubMed] [Google Scholar]
  11. Ji X., Yao Y., Li J., Yan X., Huang F. (2013). A supramolecular cross-linked conjugated polymer network for multiple fluorescent sensing. J. Am. Chem. Soc. 135, 74–77. 10.1021/ja3108559 [DOI] [PubMed] [Google Scholar]
  12. Kim H.-J., Nandajan P. C., Gierschner J., Park S. Y. (2018). Light-harvesting fluorescent supramolecular block copolymers based on cyanostilbene derivatives and cucurbit[8]urils in aqueous solution. Adv. Funct. Mater. 28:1705141 10.1002/adfm.201705141 [DOI] [Google Scholar]
  13. Kumawat L. K., Abogunrin A. A., Kickham M., Pardeshi J., Fenelon O., Schroeder M., et al. (2019). Squaramide-naphthalimide conjugates as turn-on fluorescent sensors for bromide through an aggregation-disaggregation approach. Front. Chem. 7:354. 10.3389/fchem.2019.00354 [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Lavrenova A., Balkenende D. W. R., Sagara Y., Schrettl S., Simon Y. C., Weder C. (2017). Mechano- and thermoresponsive photoluminescent supramolecular polymer. J. Am. Chem. Soc. 139, 4302–4305. 10.1021/jacs.7b00342 [DOI] [PubMed] [Google Scholar]
  15. Lee S., Chen C.-H., Flood A. H. (2013). A pentagonal cyanostar macrocycle with cyanostilbene CH donors binds anions and forms dialkylphosphate [3]rotaxanes. Nat. Chem. 5, 704–710. 10.1038/nchem.1668 [DOI] [PubMed] [Google Scholar]
  16. Li B., He T., Shen X., Tang D., Yin S. (2019). Fluorescent supramolecular polymers with aggregation induced emission properties. Polym. Chem. 10, 796–818. 10.1039/C8PY01396A [DOI] [Google Scholar]
  17. Li S.-L., Xiao T., Lin C., Wang L. (2012). Advanced supramolecular polymers constructed by orthogonal self-assembly. Chem. Soc. Rev. 41, 5950–5968. 10.1039/c2cs35099h [DOI] [PubMed] [Google Scholar]
  18. Li X., Wang L., Deng Y., Luo Z., Zhang Q., Dong S., et al. (2018). Preparation of cross-linked supramolecular polymers based on benzo-21-crown-7/secondary ammonium salt host-guest interactions. Chem. Commun. 54, 12459–12462. 10.1039/C8CC07657J [DOI] [PubMed] [Google Scholar]
  19. Lu C., Zhang M., Tang D., Yan X., Zhang Z., Zhou Z., et al. (2018). Fluorescent metallacage-core supramolecular polymer gel formed by orthogonal metal coordination and host–guest interactions. J. Am. Chem. Soc. 140, 7674–7680. 10.1021/jacs.8b03781 [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Qi L., Ding Y., Xiao T., Wu H., Diao K., Bao C., et al. (2020). Supramolecular polymerization of dioxyphenylene bridged UPy derivatives and their host-guest behaviors with the bipyridinium-based cyclophane. Chin. J. Org. Chem. 10.6023/cjoc202006070 [DOI] [Google Scholar]
  21. Shi B., Jie K., Zhou Y., Zhou J., Xia D., Huang F. (2016). Nanoparticles with near-infrared emission enhanced by pillararene-based molecular recognition in water. J. Am. Chem. Soc. 138, 80–83. 10.1021/jacs.5b11676 [DOI] [PubMed] [Google Scholar]
  22. Shi B., Zhou Z., Vanderlinden R. T., Tang J.-H., Yu G., Acharyya K., et al. (2019). Spontaneous supramolecular polymerization driven by discrete platinum metallacycle-based host–guest complexation. J. Am. Chem. Soc. 141, 11837–11841. 10.1021/jacs.9b06181 [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Sun G., Qian W., Jiao J., Han T., Shi Y., Hu X.-Y., et al. (2020). A highly efficient artificial light-harvesting system with two-step sequential energy transfer based on supramolecular self-assembly. J. Mater. Chem. A 8, 9590–9596. 10.1039/D0TA03169K [DOI] [Google Scholar]
  24. Wagner W., Wehner M., Stepanenko V., Wurthner F. (2019). Supramolecular block copolymers by seeded living polymerization of perylene bisimides. J. Am. Chem. Soc. 141, 12044–12054. 10.1021/jacs.9b04935 [DOI] [PubMed] [Google Scholar]
  25. Wang S., Xu Z., Wang T., Xiao T., Hu X.-Y., Shen Y.-Z., et al. (2018). Warm/cool-tone switchable thermochromic material for smart windows by orthogonally integrating properties of pillar[6]arene and ferrocene. Nat. Commun. 9:1737. 10.1038/s41467-018-03827-3 [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Wang Y., Cai Y., Cao L., Cen M., Chen Y., Zhang R., et al. (2019). An amphiphilic metallaclip with enhanced fluorescence emission in water: synthesis and controllable self-assembly into multi-dimensional micro-structures. Chem. Commun. 55, 10132–10134. 10.1039/C9CC04809J [DOI] [PubMed] [Google Scholar]
  27. Wehner M., Würthner F. (2020). Supramolecular polymerization through kinetic pathway control and living chain growth. Nat. Rev. Chem. 4, 38–53. 10.1038/s41570-019-0153-8 [DOI] [Google Scholar]
  28. Wei P., Yan X., Huang F. (2015). Supramolecular polymers constructed by orthogonal self-assembly based on host-guest and metal-ligand interactions. Chem. Soc. Rev. 44, 815–832. 10.1039/C4CS00327F [DOI] [PubMed] [Google Scholar]
  29. Xiao T., Feng X., Wang Q., Lin C., Wang L., Pan Y. (2013). Switchable supramolecular polymers from the orthogonal self-assembly of quadruple hydrogen bonding and benzo-21-crown-7-secondary ammonium salt recognition. Chem. Commun. 49, 8329–8331. 10.1039/c3cc44525a [DOI] [PubMed] [Google Scholar]
  30. Xiao T., Qi L., Zhong W., Lin C., Wang R., Wang L. (2019a). Stimuli-responsive nanocarriers constructed from pillar[n]arene-based supra-amphiphiles. Mater. Chem. Front. 3, 1973–1993. 10.1039/C9QM00428A [DOI] [Google Scholar]
  31. Xiao T., Wang L. (2018). Recent advances of functional gels controlled by pillar[n]arene-based host–guest interactions. Tetrahedron Lett. 59, 1172–1182. 10.1016/j.tetlet.2018.02.028 [DOI] [Google Scholar]
  32. Xiao T., Wu H., Sun G., Diao K., Wei X., Li Z.-Y., et al. (2020a). An efficient artificial light-harvesting system with tunable emission in water constructed from H-bonded AIE supramolecular polymer and Nile Red. Chem. Commun. 56, 12021–12024. 10.1039/D0CC05077F [DOI] [PubMed] [Google Scholar]
  33. Xiao T., Xu L., Götz J., Cheng M., Würthner F., Gu J., et al. (2019b). Supramolecular polymerization and cyclization of dioxynaphthalene motif bridged bifunctional UPys: minor variations in the molecular skeleton and drastic differences in self-assembly. Mater. Chem. Front. 3, 2738–2745. 10.1039/C9QM00595A [DOI] [Google Scholar]
  34. Xiao T., Xu L., Wang J., Li Z.-Y., Sun X.-Q., Wang L. (2019c). Biomimetic folding of small organic molecules driven by multiple non-covalent interactions. Org. Chem. Front. 6, 936–941. 10.1039/C9QO00089E [DOI] [Google Scholar]
  35. Xiao T., Xu L., Zhong W., Zhou L., Sun X.-Q., Hu X.-Y., et al. (2018). Advanced functional materials constructed from pillar[n]arenes. Isr. J. Chem. 58, 1183–1193. 10.1002/ijch.201800026 [DOI] [Google Scholar]
  36. Xiao T., Xu L., Zhou L., Sun X.-Q., Lin C., Wang L. (2019d). Dynamic hydrogels mediated by macrocyclic host–guest interactions. J. Mater. Chem. B 7, 1526–1540. 10.1039/C8TB02339E [DOI] [PubMed] [Google Scholar]
  37. Xiao T., Zhong W., Qi L., Gu J., Feng X., Yin Y., et al. (2019e). Ring-opening supramolecular polymerization controlled by orthogonal non-covalent interactions. Polym. Chem. 10, 3342–3350. 10.1039/C9PY00312F [DOI] [Google Scholar]
  38. Xiao T., Zhong W., Xu L., Sun X.-Q., Hu X.-Y., Wang L. (2019f). Supramolecular vesicles based on pillar[n]arenes: design, construction, and applications. Org. Biomol. Chem. 17, 1336–1350. 10.1039/C8OB03095B [DOI] [PubMed] [Google Scholar]
  39. Xiao T., Zhong W., Zhou L., Xu L., Sun X.-Q., Elmes R. B. P., et al. (2019g). Artificial light-harvesting systems fabricated by supramolecular host–guest interactions. Chin. Chem. Lett. 30, 31–36. 10.1016/j.cclet.2018.05.034 [DOI] [Google Scholar]
  40. Xiao T., Zhou L., Sun X.-Q., Huang F., Lin C., Wang L. (2020b). Supramolecular polymers fabricated by orthogonal self-assembly based on multiple hydrogen bonding and macrocyclic host–guest interactions. Chin. Chem. Lett. 31, 1–9. 10.1016/j.cclet.2019.05.011 [DOI] [Google Scholar]
  41. Xiao T., Zhou L., Wei X., Li Z., Sun X. (2020c). Supramolecular copolymers driven by quadruple hydrogen bonding and host-guest interactions. Chin. J. Org. Chem. 40, 944–949. 10.6023/cjoc201911014 [DOI] [Google Scholar]
  42. Xiao T., Zhou L., Xu L., Zhong W., Zhao W., Sun X.-Q., et al. (2019h). Dynamic materials fabricated from water soluble pillar[n]arenes bearing triethylene oxide groups. Chin. Chem. Lett. 30, 271–276. 10.1016/j.cclet.2018.05.039 [DOI] [Google Scholar]
  43. Yang L., Tan X., Wang Z., Zhang X. (2015). Supramolecular polymers: historical development, preparation, characterization, and functions. Chem. Rev. 115, 7196–7239. 10.1021/cr500633b [DOI] [PubMed] [Google Scholar]
  44. Zhang C., Li S., Zhang J., Zhu K., Li N., Huang F. (2007). Benzo-21-crown-7/secondary dialkylammonium salt [2]Pseudorotaxane- and [2]rotaxane-type threaded structures. Org. Lett. 9, 5553–5556. 10.1021/ol702510c [DOI] [PubMed] [Google Scholar]
  45. Zhang C.-W., Ou B., Jiang S.-T., Yin G.-Q., Chen L.-J., Xu L., et al. (2018). Cross-linked AIE supramolecular polymer gels with multiple stimuli-responsive behaviours constructed by hierarchical self-assembly. Polym. Chem. 9, 2021–2030. 10.1039/C8PY00226F [DOI] [Google Scholar]
  46. Zhang M., Yin S., Zhang J., Zhou Z., Saha M. L., Lu C., et al. (2017). Metallacycle-cored supramolecular assemblies with tunable fluorescence including white-light emission. Proc. Natl. Acad. Sci. U.S.A. 114, 3044–3049. 10.1073/pnas.1702510114 [DOI] [PMC free article] [PubMed] [Google Scholar]
  47. Zhang Q., Li T., Duan A., Dong S., Zhao W., Stang P. J. (2019). Formation of a supramolecular polymeric adhesive via water-participant hydrogen bond formation. J. Am. Chem. Soc. 141, 8058–8063. 10.1021/jacs.9b02677 [DOI] [PubMed] [Google Scholar]
  48. Zheng W., Chen L.-J., Yang G., Sun B., Wang X., Jiang B., et al. (2016). Construction of smart supramolecular polymeric hydrogels cross-linked by discrete organoplatinum(II) metallacycles via post-assembly polymerization. J. Am. Chem. Soc. 138, 4927–4937. 10.1021/jacs.6b01089 [DOI] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Click here for additional data file. (4.8MB, DOCX)

Data Availability Statement

The original contributions generated for the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author/s.

Articles from Frontiers in Chemistry are provided here courtesy of Frontiers Media SA

RESOURCES