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The study of aqueous-phase molecular recognition of artificial receptors is one of the frontiers in supramolecular chemistry since most biochemical processes and reactions take place in an aqueous medium and heavily rely on it. In this work, a water-soluble version of leggero pillar[5]arene bearing eight positively charged pyridinium moieties (CWP[5]L) was designed and synthesized, which exhibited good binding affinities with certain aliphatic sulfonate species in aqueous solutions. Significantly, control experiments demonstrate that the guest binding performance of CWP[5]L is superior to its counterpart water-soluble macrocyclic receptor in traditional pillararenes.

Bioinspired artificial water channels aim to combine the high permeability and selectivity of biological aquaporin (AQP) water channels with chemical stability. Here, we carefully characterized a class of artificial water channels, peptide-appended pillar[5]arenes (PAPs). The average single-channel osmotic water permeability for PAPs is 1.0(±0.3) × 10−14cm³/s or 3.5(±1.0) × 10⁸ water molecules per s, which is in the range of AQPs (3.4∼40.3 × 10⁸ water molecules per s) and their current synthetic analogs, carbon nanotubes (CNTs, 9.0 × 10⁸ water molecules per s). This permeability is an order of magnitude higher than first-generation artificial water channels (20 to ∼10⁷ water molecules per s). Furthermore, within lipid bilayers, PAP channels can self-assemble into 2D arrays. Relevant to permeable membrane design, the pore density of PAP channel arrays (∼2.6 × 10⁵ pores per μm²) is two orders of magnitude higher than that of CNT membranes (0.1∼2.5 × 10³ pores per μm²). PAP channels thus combine the advantages of biological channels and CNTs and improve upon them through their relatively simple synthesis, chemical stability, and propensity to form arrays.

This study presents a modified silica gel used as the solid support that an adsorbent modified by pillar[5]arene as a new and efficient absorbent ( Si-APTMS-pillar[5]arene ) was used for the removal of Cu(II) ions from aqueous solution. XRD, FT-IR, and SEM analysis were used to characterize the morphology and structure of the Si-APTMS-pillar[5]arene adsorbent material. The maximum adsorption capacities of Cu(II) ions at dissimilar temperatures via the Langmuir model were 75.1880 mg/g (298 K), 76.3359 mg/g (308 K), 78.1250 mg/g (318 K), and 79.3651 mg/g (328 K), respectively, at 90 min and pH 5.0. The selectivity to Cu(II) ions is quite high, and especially the prepared adsorbent showed high reusability and maintained its high efficiency even after 3–5 cycles of regeneration. Si-APTMS-pillar[5]arene adsorbent prepared for the effective treatment of water and copper-contaminated wastewater is promising as a new, cost-effective, and non-toxic adsorption technique. Graphical abstract

Supramolecular polymers have attracted considerable interest due to their intriguing features and functions. The dynamic reversibility of noncovalent interactions endows supramolecular polymers with tunable physicochemical properties, self-healing, and externally stimulated responses. Among them, pillararene-based supramolecular polymers show great potential for biomedical applications due to their fascinating host–guest interactions and easy modification. Herein, we summarize the state of the art of pillararene-based supramolecular polymers for cancer therapy and illustrate its developmental trend and future perspective.

The separation of chlorobenzene (CB) and chlorocyclohexane (CCH) using traditional industrial separation technologies (distillation, fractionation, and rectification) is a great challenge due to their close boiling points. Here, we report an innovative method for the separation of the mixture of CB and CCH by nonporous adaptive crystals (NACs) of perethylated pillar[6]arene (EtP6). NACs of EtP6 (EtP6α) can selectively adsorb CCH vapor from the vapor mixture of CB and CCH (v:v = 1:1) with a purity of 99.5%. Furthermore, EtP6α can be recycled for five times without a significant loss of performance.

Host-guest motifs are likely the most recognizable manifestation of supramolecular chemistry. These complexes are characterized by the organization of small molecules on the basis of preferential association of a guest within the portal of a host. In the context of their therapeutic use, the primary application of these complexes has been as excipients which enhance the solubility or improve the stability of drug formulations, primarily in a vial. However, there may be opportunities to go significantly beyond such a role and leverage key features of the affinity, specificity, and dynamics of the interaction itself toward \"smarter\" therapeutic designs. One approach in this regard would seek stimuli-responsive host-guest recognition, wherein a complex forms in a manner that is sensitive to, or can be governed by, externally applied triggers, disease-specific proteins and analytes, or the presence of a competing guest. This review will highlight the general and phenomenological design considerations governing host-guest recognition and the specific types of chemistry which have been used and are available for different applications. Finally, a discussion of the molecular engineering and design approaches which enable sensitivity to a variety of different stimuli are highlighted. Ultimately, these molecular-scale approaches offer an assortment of new chemistry and material design tools toward improving precision in drug delivery.

Calixarenes and related macrocycles have been shown to have antimicrobial effects since the 1950s. This review highlights the antimicrobial properties of almost 200 calixarenes, resorcinarenes, and pillararenes acting as prodrugs, drug delivery agents, and inhibitors of biofilm formation. A particularly important development in recent years has been the use of macrocycles with substituents terminating in sugars as biofilm inhibitors through their interactions with lectins. Although many examples exist where calixarenes encapsulate, or incorporate, antimicrobial drugs, one of the main factors to emerge is the ability of functionalized macrocycles to engage in multivalent interactions with proteins, and thus inhibit cellular aggregation.

The solvent‐free mechanochemical acylation of pillar[5]arene‐based daisy chain monomers bearing either an alcohol or an amine function has been investigated in details. These chemical transformations have been also carried out in solution for comparison purposes. Whereas stoppered [c2]daisy chain derivatives have been obtained from the amine monomer whatever the conditions, stoppered [c2]daisy chain derivatives could be only obtained from the corresponding alcohol under mechanochemical conditions. In this particular case, concentration effects are clearly beneficial when the reactions are performed under solvent‐free conditions as daisy chain assemblies are effectively present in the solid state despite the very weak affinity of the 11‐hydroxy‐undecyl subunit for the pillar[5]arene moiety. [c2]Daisy chain rotaxanes have been prepared under solvent‐free mechanochemical conditions by acylation of pillar[5]arene derivatives bearing either a 11‐hydroxy‐undecyl or 11‐amino‐undecyl subunit. Concentration effects are clearly beneficial as daisy chain assemblies are effectively present in the solid state despite the very weak affinity of the undecyl chain for the pillar[5]arene moiety.

Photodynamic therapy (PDT) as a safe, non-invasive modality for cancer therapy, in which the low oxygen and high glutathione in the tumor microenvironment reduces therapeutic efficiency. In order to overcome these problems, we prepared a supramolecular photosensitive system of O2-Cu/ZIF-8@ZIF-8@WP6–MB (OCZWM), which was loaded with oxygen to increase the oxygen concentration in the tumor microenvironment, and the Cu2+ in the system reacted with glutathione (GSH) to reduce the GSH concentration to generate Cu+. It is worth noting that the generated Cu+ can produce the Fenton reaction, thus realizing the combination therapy of PDT and chemodynamic therapy (CDT) to achieve the purpose of significantly improving the anti-cancer efficiency.

Efficient and energy‐saving separation of benzene isomers bearing a diverse range of functional groups is a great challenge due to their overlapping physicochemical properties. Here, we report the successfully use of a water‐soluble pillar[5]arene (WP5) as a multifunctional material for the separation and detection of meta/ortho‐substituted benzene isomers in water. A liquid‐liquid extraction strategy was used for the separation of these benzene isomers based on their different affinity for WP5 in water. The selectivities for the meta over the ortho isomer for xylenes, chlorotoluene, and bromotoluene was 88.6 %, 88.3 %, and 95.0 % respectively, in one extraction cycle. Furthermore, a fluorescence indicator system based on WP5 and a fluorescent dye molecule (10‐methylacridinium, D) was adopted and exhibited significant fluorescence and optical discrimination upon the addition of meta‐ compared to ortho‐xylene, which implies that a simple “turn‐on” detection can be performed prior to engaging in the separation process. Efficient extraction: A water‐soluble pillar[5]arene (WP5) was used for the separation of meta/ortho‐substituted benzene isomers under ambient conditions with over 88 % selectivity for the meta isomer. Furthermore, a fluorescence indicator system based on WP5 and a fluorescent dye molecule (10‐methylacridinium, D) showed significant fluorescence and optical discrimination between the meta/ortho isomers, which implies that a simple “turn‐on” detection can be performed prior to engaging in the separation process.