Arene-based Host Guest Research Articles

A Temperature-Sensitive Fluorescent Supramolecular Polymer Constructed by Discrete Platinum(II) Metallacycle and Pillar[5]arene-Based Host-Guest Interactions.

The application of thermosensitive fluorescent supramolecular polymers in advanced optical materials, chemical sensors, artificial optical devices, and external stimulus responses remains underdeveloped. In this study, we introduced a novel method for constructing a mechanically interlocked fluorescent supramolecular polymer utilizing host-guest interactions, including C-H···π interactions and π-π stacking. This polymer exhibits outstanding temperature-sensitive fluorescence properties and is environmentally friendly due to its recyclability. Leveraging the polymer's fluorescence response at critical temperature ranges, we developed a high-temperature warning device. This device utilizes the temperature-sensitive fluorescence characteristic of the polymer to indicate dangerous temperature levels, thereby demonstrating its potential in practical safety applications.

Selective wetting and transport of systemic pesticides on bionic stomatal surface regulated by host–guest interaction

Pesticide residues in the environment pose serious threats to ecosystem and human health, and how to achieve the selective transport and enrichment of specific pesticide residues through hydrophobic surface are still an important challenge. Herein, inspired by the “stomatal gating effect” of plant leaves, amino pillar[5]arene-based host–guest gating systems are introduced into artificial porous surfaces with hydrophobicity to fabricate bionic stomatal surfaces (AP5A porous surface), which is expected to modulate the interaction between pesticide and bionic surface through host–guest interaction to selective promote the wetting and transport of specific pesticide on the surface. Experimental and simulation results indicated the AP5A porous surface would selectively capture and adsorb the triclopyr pesticide by strong host–guest interaction to enhance pesticide wettability, and realized the host–guest interaction induced fast transport and enrichment of triclopyr (246.4 μM cm−2h−1) on the bionic stomatal surface. This work provides a new perspective that host–guest interaction between pesticides and solid surface as a gating switch to selective induce the systemic pesticides wetting and transport on bionic porous surface, which is believed to be useful in applications such as the enrichment and removal of pesticide residues from environment in the future.

A supramolecular oligo[2]rotaxane constructed by orthogonal platinum(II) metallacycle and pillar[5]arene-based host–guest interactions

Oligo[n]rotaxanes are one of the most extensively studied categories of mechanically bonded macromolecules. In this study, a supramolecular oligo[2]rotaxane is successfully constructed driven by platinum(II) metallacycle and pillar[5]arene-based host–guest interactions in an orthogonal way. The supramolecular oligo[2]rotaxane is further applied in fabricating a light harvesting system.

L-ribose specific recognition surface constructed by pillar[5]arene-based host–guest interaction

In living organisms, chiral molecules have specific chiral conformations that produce different physiological effects. Ribose is one of the components of RNA, which mainly plays a role in regulating biological activity. Inspired by the biological recognition of sugars, functional chiral surfaces for recognizing L-ribose through non-covalent interactions were constructed. In the strategy of this study, a functional chiral gold surface based on host-guest interactions was constructed through the assembly of the host molecule single-function alynyl pillar[5]arene(SAP5) and the guest molecule (S) -mandelate-violet (SMV). The association constant of SMV and SAP5 was calculated to be 2.95×104 M-1, with a binding ratio of 1:1. By impedance and contact angle detection, the constructed functional interface has good detection effect on L-ribose in the range of 1×10-7 M to1× 10-2 M. In addition, CV was disassembled from the aromatic cavity of pillar[5]arene after adding zinc powder and it can repeat five times with good recyclability, thus achieving the organic combination of interface recognition and intelligence.

Supramolecular Modulation of Tumor Microenvironment through Pillar[5]arene-Based Host-Guest Recognition to Synergize Cancer Immunotherapy.

Despite the tremendous breakthrough of immunotherapy, the low response rate and resistance of immune checkpoint inhibitors (ICIs) toward solid tumors occur frequently. A highly hypoxic tumor microenvironment (TME) provides tumor cells with high concentrations of HIF-1α and polyamines to evade immune cell destruction. Reprogramming of an immunogenic TME has exhibited a brilliant future to boost immunotherapeutic performances. Herein, a supramolecular nanomedicine (TAPP) is developed on the basis of host-guest molecular recognition and metal coordination, showing the capability to remodel the immunosuppressive TME. Tamoxifen (Tmx) and Fe3+ are encapsulated into TAPP to achieve the combination of chemotherapy and chemodynamic therapy (CDT). Tmx directly downregulates HIF-1α, and a pillar[5]arene-based macrocyclic host successfully eliminates polyamines in tumors. Enhanced immunogenic cell death is achieved by Tmx and Fe3+, and the therapeutic efficacy is further synergized by immune checkpoint blockade (ICB) therapy. This supramolecular reprogramming modality encourages cytotoxic T lymphocyte infiltration, achieving pre-eminent immune response and long-term tumor suppression.

Multistep sequence-controlled supramolecular polymerization by the combination of multiple self-assembly motifs

The precise sequence control of polymer chain is an important research topic of polymer chemistry. Although some methods such as iterative synthesis and supramolecular polymerization have been developed to fabricate sequence-controllable polymer, it is still a great challenge to consecutively prepare multiple supramolecular polymers with different sequence structures. In this work, through the reasonable utilization of assembly motifs, we integrated multiple host-guest recognitions and metal coordination interactions to prepare different sequence-controlled supramolecular polymers by a multistep assembly strategy. This research provides inspiration for the design and preparation of supramolecular polymers with different sequence structures.

Supramolecular aggregates constructed by pillar[5]arene-based host–guest interaction with aggregation-induced emission

Supramolecular aggregates with aggregation-induced emission were constructed by pillar[5]arene-based host–guest interaction.

Enhancing Mechanical Performance of a Polymer Material by Incorporating Pillar[5]arene-Based Host-Guest Interactions.

Polymer gels have been widely used in the field for tissue engineering, sensing, and drug delivery due to their excellent biocompatibility, hydrophilicity, and degradability. However, common polymer gels are easily deformed on account of their relatively weak mechanical properties, thereby hindering their application fields, as well as shortening their service life. The incorporation of reversible non-covalent bonds is capable of improving the mechanical properties of polymer gels. Thus, here, a poly(methyl methacrylate) polymer network was prepared by introducing host–guest interactions between pillar[5]arene and pyridine cation. Owing to the incorporated host–guest interactions, the modified polymer gels exhibited extraordinary mechanical properties according to the results of the tensile tests. In addition, the influence of the host–guest interaction on the mechanical properties of the gels was also proved by rheological experiments and swelling experiments.

Tumor microenvironment responsive polypeptide-based supramolecular nanoprodrugs for combination therapy

Tumor microenvironment responsive nanomedicine has drawn considerable attention for combination therapy, but still remains a significant challenge for less side effects and enhanced anti-tumor efficiency. Herein, we develop a pH/ROS dual-responsive supramolecular polypeptide nanoprodrug (PFW-DOX/GOD) by using pillar[5]arene-based host-guest strategy for combined glucose degradation, chemodynamic therapy (CDT), and chemotherapy (CT). The PFW-DOX/GOD consists of a pH-responsive ferrocene/pillar[5]arene-containing polypeptide, a ROS-responsive polyprodrug, and encapsulated glucose oxidase (GOD). Upon into intracellular acidic environment, PFW-DOX/GOD exhibits rapid pH-triggered disassembly behavior. Simultaneously, the released GOD can catalyze intratumoral glucose into massive H2O2, which are further converted into highly toxic hydroxyl radicals (•OH) by the catalysis of ferrocene via the Fenton reaction. Thereafter, induced by the ROS-responsive cleavage of thioketal linkage, the conjugated DOX prodrug was released and activated. The combined glucose degradation, chemodynamic therapy (CDT), and chemotherapy (CT) of PFW-DOX/GOD present anti-tumor effect with 96% of tumor inhibitory rate (TIR). Therefore, such tumor microenvironment-responsive supramolecular polypeptide nanoprodrugs represent a potential candidate for combination therapy with minimal side effects. Statement of significanceIn this work, a tumor microenvironment-responsive supramolecular polypeptide nanoprodrug (PFW-DOX/GOD) was prepared via pillar[5]arene-based host-guest interactions, and presented low side effects and high tumor accumulation owing to the diameters of about 200 nm and surface PEG segment. After pH-responsive release of GOD in the intracellular acidic environment, the cascade catalytic reactions including GOD-catalyzed degradation of intratumoral glucose and Fenton reaction, effectively happened to generate •OH for chemodynamic therapy (CDT), which subsequently induced the cleavage of thioketal linkage to activate free DOX for chemotherapy (CT). Collectively, this supramolecular polypeptide nanoprodrugs provide a promising strategy for combination therapy with synergetic anti-tumor effect.

A supramolecular polymer network constructed by pillar[5]arene-based host–guest interactions and its application in nitro explosive detection

A supramolecular polymer network constructed by pillar[5]arene-based host–guest interactions and its application in nitro explosive detection

Cross-linked supramolecular polymer networks constructed by pillar[5]arene-based host–guest recognition and coordination/oxidation of catechol

Two cross-linked supramolecular polymers are constructed by pillar[5]arene-based molecular recognition and mussel-inspired coordination/oxidation of catechol.

Enhancing the Stability and Photothermal Conversion Efficiency of ICG by Pillar[5]arene-Based Host-Guest Interaction.

Indocyanine green (ICG) is a classical near-infrared (NIR) photothermal reagent that can be employed in clinical medical detection. Under neutral conditions, ICG can adsorb NIR light effectively for photothermal (PTT) and photodynamic (PDT) therapy. However, ICG is easily degraded in weak acid environments, which seriously restricts its application. In this work, a cationic water-soluble pillar[5]arene (WP5) was selected as the stabilizing agent for ICG. Thanks to the host-guest interaction between WP5 and alkyl sulfonate, the stability and the photothermal conversion efficiency of ICG increased remarkably upon addition of WP5 as investigated by UV-vis spectrum and photothermal studies. Furthermore, an in vitro study showed higher efficiency of WP5&ICG in killing cancer cells in a shorter treatment time than the free ICG. Hence, it is hopeful that WP5 can be a new type of supramolecular host in enhancing the stability and photothermal conversion efficiency of photosensitizers.

Recent Applications of Pillar[n]arene-Based Host-Guest Recognition in Chemosensing and Imaging.

Pillar[n]arene is a novel kind of synthetic supramolecular macrocyclic host characterized by its particular pillar-shaped structure consisting of an electron-rich cavity and two finely adjustable rims. Benefiting from its rigid structure, facile synthesis, ease of functionalization, and outstanding host-guest chemistry, pillar[n]arene shows great potential for diverse applications. Significantly, the host-guest recognition of pillar[n]arene provides a novel approach for chemosensing and imaging. Herein, this Review critically and comprehensively reviews the applications of pillar[n]arene-based host-guest recognition in chemosensing and imaging. The sensing and imaging mechanisms as well as the unique roles and advantages of pillar[n]arene-based host-guest recognition are summarized. In addition, preparations of hybrid materials based on pillar[n]arene and inorganic materials are also introduced comprehensively in the light of chemosensing and imaging. Finally, current challenges and perspectives on pillar[n]arene-based host-guest recognition in chemosensing and imaging are outlined.

A selective and stable vapochromic system constructed by pillar[5]arene-based host–guest interactions

The development of new strategies for the construction of highly selective and stable vapochromic system is still in great demand. Here, we present a highly selective and stable vapochromic system constructed by pillar[5]arene-based host–guest interactions between a pillar[5]arene (EtP5) and a phenazine derivative. The present material in this work showed specific selective responsiveness to chloroform vapor. The resultant dark orange solid sample was highly stable, which can maintain the color in air for at least two months at room temperature. Moreover, CHCl3 vapor responsive thin film and light-emitting diode (LED) was successfully prepared by coating the EtP5⊃1 complex on a glass sheet and a commercially available UV-LED. This work provided a new approach for the design and construction of selective and stable vapochromic systems with obvious color changes using pillar[5]arene-based host–guest interactions.

Chiral Nanochannels of Ordered Mesoporous Silica Constructed by a Pillar[5]arene-Based Host-Guest System.

The separation of racemic compounds by chiral nanochannels has attracted extensive attention. However, the fabrication of high-performance chiral nanochannels is still a challenge owing to the difficulty in magnifying the weak chiral interaction to macroscopic properties of materials. Herein, by introducing a l-alanine-pillar[5]arene host to achiral ordered mesoporous silica (OMS), chiral OMS nanochannels were fabricated, which exhibited excellent selectivity (ee value up to 90.2%) to separate racemic drugs with promising reusability and stability. Besides, it was identified that enantioselective separation took place through a molecular-recognition-adsorbed transport mechanism. This work highlights the great potential of chiral OMS nanochannels as a platform for enantioselective separation.

Formation of a lead chalcogenide quantum dot-based supramolecular polymer network via pillar[5]arene-based host–guest complexation

We presented the construction of a lead chalcogenide quantum dot-based fluorescent supramolecular polymer network driven by pillar[5]arene-based host–guest complexation.

Supramolecular nanoparticles constructed from pillar[5]arene-based host–guest complexation with enhanced aggregation-induced emission for imaging-guided drug delivery

Supramolecular nanoparticles with enhanced aggregation-induced emission are prepared by taking advantage of pillar[5]arene-based host–guest complexation, and are sophisticated nanocarriers for imaging-guided drug delivery.

PH/ROS Dual-Responsive Supramolecular Vesicles Fabricated by Carboxylated Pillar[6]arene-Based Host-Guest Recognition and Phenylboronic Acid Pinacol Ester Derivative.

The pH and reactive oxygen species (ROS) dual-responsive supramolecular vesicle utilizing a novel host-guest molecular recognition between a phenylboronic acid pinacol ester derivative carrying long alkyl chain (PBEC12A) and carboxylated pillar[6]arene (CP[6]) is developed. The host-guest complexation between CP[6] and PBEC12A was first studied in aqueous solution. PBEC12A was encapsulated within CP[6] forming a stable host-guest complex with a binding constant as high as 106 M-1 order of magnitude. The driving force behind such a host-guest recognition was the combination of electrostatic interaction and hydrophobic effect. Then, the self-assembly of the supra-amphiphiles of PBEC12A-CP[6] host-guest complexes was investigated in aqueous solution through high-resolution transmission electron microscope and dynamic light scattering. It was found that the supra-amphiphiles self-assembled into supramolecular vesicles and the size of the self-assembled supramolecular vesicles could be tuned from 25 to 200 nm by varying the ratio of CP[6] to PBEC12A. To demonstrate the pH- and ROS-responsive properties of the self-assembled vesicles, the supramolecular vesicles self-assembled from PBEC12A/CP[6] (5:1) were utilized. The Nile Red loading and release studies demonstrated that the supramolecular vesicles possessed good pH/ROS dual-responsive properties. This study enriches the field of supra-amphiphile based on noncovalent interactions. It is anticipated that the pH/ROS dual-responsive supramolecular vesicles have potential applications in drug-delivery systems because both the stimuli are in close relation with specific microenvironments of tumors and relevant diseases of the human body.

Supramolecular polymer networks based on pillar[5]arene: synthesis, characterization and application in the Fenton reaction.

A new type of supramolecular polymeric material was constructed efficiently via orthogonal pillar[5]arene-based host-guest and hydrogen bond interactions. The supramolecular polymeric materials prove to be a good catalyst for the Fenton reaction in water.

Spreading of benquitrione droplets on superhydrophobic leaves through pillar[5]arene-based host-guest chemistry.

Spreading of agricultural sprays on plant surfaces is a significant task as it helps decrease pesticide usage and thereby reduces the risk of environmental pollution. Here, we report a method of increasing the spreading of herbicide benquitrione droplets on superhydrophobic surfaces through its selective dynamic self-assembly with amino pillar[5]arenes. Supramolecular interaction such as host-guest interaction was utilized for the complete diffusion of benquitrione over the hydrophobic plant surface. Furthermore, molecular dynamics simulations were used to verify that AP5A improved the spreading of benquitrione droplets on superhydrophobic interfaces. Moreover, complexation of benquitrione did not affect its biological activity. The present work provides a new method for improving the utilization rate of pesticides and reducing pesticide use.