Separation of Monochlorotoluene Isomers by Nonporous Adaptive Crystals of Perethylated Pillar[5]arene and Pillar[6]arene

Supramolecular Assembly Frameworks (SAFs): Shaping the Future of Functional Materials

Supramolecular assembly frameworks (SAFs) represent a new category of porous materials, utilizing non-covalent interactions, setting them apart from metal-organic frameworks (MOFs) and covalent organic frameworks (COFs). This category includes but is not restricted to hydrogen-bonded organic frameworks and supramolecular organic frameworks. SAFs stand out for their outstanding porosity, crystallinity, and stability, alongside unique dissolution-recrystallization dynamics that enable significant structural and functional modifications. Crucially, their non-covalent assembly strategies allow for a balanced manipulation of porosity, symmetry, crystallinity, and dimensions, facilitating the creation of advanced crystalline porous materials unattainable through conventional covalent or coordination bond synthesis. Despite their considerable promise in overcoming several limitations inherent to MOFs and COFs, particularly in terms of solution-processability, SAFs have received relatively little attention in recent literature. This Minireview aims to shed light on standout SAFs, exploring their design principles, synthesis strategies, and characterization methods. It emphasizes their distinctive features and the broad spectrum of potential applications across various domains, aiming to catalyze further development and practical application within the scientific community.

Highly Efficient Separation of BTEX via Amide Naphthotube Cavity-Confined Tandem C/N-H···π Interactions

The separation of BTEX [benzene, toluene, ethylbenzene (EB), and xylene isomers] poses a huge challenge in the industry, attributed to their similar structures and physical properties. Supramolecular compounds show great promise for hydrocarbon separation. Herein, we designed two pairs of endo-functionalized amide naphthotubes with methyl and benzyl side chains, which were first employed as chromatographic separation materials and exhibited high shape-selectivity for BTEX. In particular, the amide naphthotubes with methyl side chains provided complete separation toward BTEX and anti-3a showed high selectivity for the p-xylene over other isomers with αPX/OX = 9.34, αPX/MX = 5.50, and αPX/EB = 4.30. The mechanism of BTEX separation originates from the synergistic effect of specially confined tandem N-H···π and C-H···π interactions toward aromatic compounds. The findings of this research show promise for practical applications in efficiently separating crucial aromatic isomers.

Pillararenes: a new frontier in antimicrobial therapy

Pillararenes have gained great interest among researchers in many fields due to their symmetric structure and facile functionalization. In this review, we summarize recent progress for pillararenes as antimicrobial agents, ranging from cationic pillararenes and peptide-modified pillararenes to sugar-functionalized pillararenes. Moreover, their structure-activity relationships are presented, and their mechanisms of action are discussed. As a state-of-the-art technology, their opportunities and outlook are also outlined in this emerging field. Overall, their potent inhibitory activity and high biocompatibility give them potential for the development of novel antimicrobial agents.

Recent Progress of Supramolecular Chemotherapy Based on Host-Guest Interactions

Chemotherapy is widely recognized as an effective approach for treating cancer due to its ability to eliminate cancer cells using chemotherapeutic drugs. However, traditional chemotherapy suffers from various drawbacks, including limited solubility and stability of drugs, severe side effects, low bioavailability, drug resistance, and challenges in tracking treatment efficacy. These limitations greatly hinder its widespread clinical application. In contrast, supramolecular chemotherapy, which relies on host-guest interactions, presents a promising alternative by offering highly efficient and minimally toxic anticancer drug delivery. In this review, an overview of recent advancements in supramolecular chemotherapy based on host-guest interactions is provided. The significant role it plays in guiding cancer therapy is emphasized. Drawing on a wealth of cutting-edge research, herein, a timely and valuable resource for individuals interested in the field of supramolecular chemotherapy or cancer therapy, is presented. Furthermore, this review contributes to the progression of the field of supramolecular chemotherapy toward clinical application.

Preparation and evaluation of two chiral stationary phases based on imidazolyl-functionalized bromoethoxy pillar[5]arene-bonded silica

Chiral pillar[5]arene-based mesoporous silica, an emerging class of chiral structure, possesses excellent characteristics such as abundant chiral active sites, encapsulated cavity and excellent chiral modification, which make them a promising candidate as new chiral stationary phases (CSPs) in enantioseparation. In this study, two imidazole-containing (S)-1-(4-phenyl-1H-imidazol-2-yl)ethanamine and (S)-Histidinol were respectively modified to bromoethoxy pillar[5]arene-bonded silica to construct new chiral stationary phases (sPIE-BP5-Sil and sHol-BP5-Sil) for the separation and analysis of enantiomers. The separation conditions such as mobile phase composition, flow rate and temperature were optimized. Under optimal conditions, both sPIE-BP5-Sil and sHol-BP5-Sil showed good separation performance for different types of enantiomers. Interestingly, sPIE-BP5-Sil and sHol-BP5-Sil showed better enantioselectivity for chiral aromatic compounds and chiral aliphatic compounds, respectively. This enantioseparation result was closely related to the presence of additional aromatic rings and abundant hydroxyl groups in the side chains of the two chiral groups. In addition, the enantioseparation process was further studied by molecular docking simulation. Therefore, this work provided a new strategy for the preparation and application of imidazolyl-derived pillar[5]arene-based chiral stationary phases, which can be efficiently used for screening and separating enantiomers.

Cis-Trans and Length-Selective Molecular Discrimination of Halogenated Organic Compounds by a Crystalline Hybrid Macrocyclic Arene

The development of adsorbents with robust molecular discrimination capabilities for halogenated organic compounds (HOCs) holds significant importance due to their potential in adsorptive separation and mitigation of associated health risks. In this study, we report a molecular discrimination behavior based on crystalline hybrid macrocyclic arene H, offering precise capture of cis-trans isomers and length-selective separation of HOCs. The activated H crystals (Hα) demonstrate exceptional discrimination and separation performance by selectively capturing trans-1,2-dichloroethylene (trans-DCE) from cis/trans-isomer mixtures with a high selectivity of 98.8%. Evidenced by single-crystal X-ray diffraction and density functional theory (DFT) calculations, this high adsorption selectivity arises from the formation of more stable complex crystals between H and the preferred guest trans-DCE. Moreover, Hα exhibits the ability to selectively trap size-matched 1,2-dibromoethane (DBE) from mixtures of alkylene dibromides with varying alkane-chain lengths, although their capture and separation are recognized to be difficult as a consequence of low-polarity bonds. The solid-state transformations between guest-free and guest-containing Hα crystals indicate their recyclability, showcasing promising prospects for potential applications.

Polydopamine modified by pillar[5]arene in situ for targeted chemo-photothermal cancer therapy

A pillar[5]arene-modified polydopamine (PDA-P[5]OH) displaying pH/NIR dual-responsive properties was constructed successfully in situ for targeted chemo-photothermal cancer therapy.

Supramolecular host-guest nanosystems for overcoming cancer drug resistance

Cancer drug resistance has become one of the main challenges for the failure of chemotherapy, greatly limiting the selection and use of anticancer drugs and dashing the hopes of cancer patients. The emergence of supramolecular host-guest nanosystems has brought the field of supramolecular chemistry into the nanoworld, providing a potential solution to this challenge. Compared with conventional chemotherapeutic platforms, supramolecular host-guest nanosystems can reverse cancer drug resistance by increasing drug uptake, reducing drug efflux, activating drugs, and inhibiting DNA repair. Herein, we summarize the research progress of supramolecular host-guest nanosystems for overcoming cancer drug resistance and discuss the future research direction in this field. It is hoped that this review will provide more positive references for overcoming cancer drug resistance and promoting the development of supramolecular host-guest nanosystems.

Potential of nonporous adaptive crystals for hydrocarbon separation

Hydrocarbon separation is an important process in the field of petrochemical industry, which provides a variety of raw materials for industrial production and a strong support for the development of national economy. However, traditional separation processes involve huge energy consumption. Adsorptive separation based on nonporous adaptive crystal (NAC) materials is considered as an attractive green alternative to traditional energy-intensive separation technologies due to its advantages of low energy consumption, high chemical and thermal stability, excellent selective adsorption and separation performance, and outstanding recyclability. Considering the exceptional potential of NAC materials for hydrocarbon separation, this review comprehensively summarizes recent advances in various supramolecular host-based NACs. Moreover, the current challenges and future directions are illustrated in detail. It is expected that this review will provide useful and timely references for researchers in this area. Based on a large number of state-of-the-art studies, the review will definitely advance the development of NAC materials for hydrocarbon separation and stimulate more interesting studies in related fields.

Efficient separation of monobromotoluene isomers by nonporous adaptive perbromoethylated pillar[5]arene crystals

Herein we report an efficient adsorptive separation approach for monobromotoluene isomers using nonporous adaptive crystals of perbromoethylated pillar[5]arene (BrP5). The purity of separated m-bromotoluene from an equal volume mixture of m-bromotoluene and o-bromotoluene reaches 96.6% in one cycle and the adsorbent BrP5 can be reused without losing separation performance.

Efficient gas chromatographic separation of xylene and other aromatic isomers by using pillar[6]arene-based stationary phase

The separation of aromatic isomers, in particular xylene isomers, represents a big issue in chemical and petroleum industries, owing to their similar molecular sizes and boiling points. In this work, the investigation ofpillar[6]arene derivative modified by long alkyl chains (P6A-C10) as a stationary phase for high-resolution gas chromatographic (GC) separations of xylene isomers is presented. Pillar[n]arenes are a new class of macrocyclic hosts that can accommodate specific guests due to their highly symmetrical and rigid pillar architectures with π-electron rich cavities. The P6A-C10 column showed high-resolution performance towards xylene isomers, with peculiar advantages if compared with the commercial HP-5, HP-35, DB-17, and PEG-20Mcolumns.A quantum chemistry calculation has been performed, showing a difference in non-covalent interactions with the P6A-C10 pillar framework, which leads to specific selectivity for xylene isomers.Furthermore, the P6A-C10 column exhibited good repeatability.

Efficient Purification of 2,6-Lutidine by Nonporous Adaptive Crystals of Pillararenes

2,6-Lutidine (2,6-LT) is a very important raw material in the chemical industry, but the impurities of 3-picoline (3-PC) and 4-picoline (4-PC) existing in 2,6-LT seriously affect its quality. Considering different molecular sizes of these three compounds, herein, we exploit nonporous adaptive crystals (NACs) of pillararenes as purifying agents for removal of 3-PC and 4-PC in 2,6-LT. We find that per-ethylated pillar[5]arene (EtP5) can selectively adsorb 3-PC and 4-PC, while negligible capture of 2,6-LT is observed, resulting in improvement of the purity of 2,6-LT up to 94.9%. Single-crystal structures indicate that the excellent selectivity originates from the size match and complexation stability differences among different host/guest pairs. After purification, NACs of EtP5 can be easily regenerated and used in the next run without a significant performance degradation.

Adsorptive separation of para-xylene by nonporous adaptive crystals of phenanthrene[2]arene

In this work, we developed a new method for the preparation of phenanthrene[2]arene on a large-scale. Meanwhile, the synthetic phenanthrene[2]arene has been successfully used as nonporous adaptive crystals for the separation of para-xylene (pX) from xylene isomers. The crystal structure revealed that one host molecule can adsorb one pX molecule to form the 1@pX complex, in which pX is located in the cavity of the host.

A new method for the preparation of phenanthrene[2]arene on a large-scale was developed. The synthetic phenanthrene[2]arene has been successfully used as nonporous adaptive crystals for the separation of para-xylene from xylene isomers.

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.

Separation of pyrrolidine from tetrahydrofuran by using pillar[6]arene-based nonporous adaptive crystals

Pyrrolidine, an important feedstock in the chemical industry, is commonly produced via vapor-phase catalytic ammoniation of tetrahydrofuran (THF). Obtaining pyrrolidine with high purity and low energy cost has extremely high economic and environmental values. Here we offer a rapid and energy-saving method for adsorptive separation of pyrrolidine and THF by using nonporous adaptive crystals of per-ethyl pillar[6]arene (EtP6). EtP6 crystals show a superior preference towards pyrrolidine in 50 : 50 (v/v) pyrrolidine/THF mixture vapor, resulting in rapid separation. The purity of pyrrolidine reaches 95% in 15 min of separation, and after 2 h, the purity is found to be 99.9%. Single-crystal structures demonstrate that the selectivity is based on the stability difference of host-guest structures after uptake of THF or pyrrolidine and non-covalent interactions in the crystals. Besides, EtP6 crystals can be recycled efficiently after the separation process owing to reversible transformations between the guest-free and guest-loaded EtP6.

Lanthanide-organic pincer hosts with allosteric-controlled metal ion binding specificity

A series of lanthanide-organic pincer hosts were synthesized, which showed allosteric-controlled metal ion binding selectivities due to the lanthanide-induced subtle changes of the central vacant binding site.

Highly Chiral Selective Resolution in Pillar[6]arenes Functionalized Microchannel Membranes

High flux microchannel membranes have the potential for large scale separations. However, it is prevented by poor enantioselectivity. Therefore, the development of a high-enantioselective microchannel membrane is of great importance for large scale chiral separations. In this work, chiral gold nanoparticles are incorporated into the microchannel membrane to astringe the large pores and improve the enantioselectivity. Here, the gold nanoparticles are functionalized by l-phenylalanine-derived pil-lararenes (l-Phe-P6@AuNPs) as the chiral receptor of R-phenylglycinol (R-PGC) over its enantiomer. This chiral Au NPs coated microchannel membrane (l-Phe-P6@AuNPs microchannel) shows a selectivity of 5.40 for R-PGC and a flux of 140.35 nmol·cm^-2·h^-1, where the enantioselectivity is improved, ensuring its flux. Compared with the enantioselectivity and flux of nanochannel membranes reported in literatures, the l-Phe-P6@AuNPs microchannel has the advantage for enantioselectivity and flux for chiral separation.

Adsorptive separation of picoline isomers by adaptive calix[3]acridan crystals

The exploration of macrocycle-based nonporous adaptive crystals (NACs) for adsorption and separation has been one of the hotspots in supramolecular chemistry and crystal engineering. Herein, we developed calix[3]acridan-based NACs to separate industrially important 4-picoline from its isomer mixtures with over 93.8% purity.

Selective Extraction, Recovery, and Sensing of Hydroquinone Mediated by a Supramolecular Pillar[5]quinone Quinhydrone Charge-Transfer Complex

Intermolecular interactions between an electron-rich aromatic hydroquinone (HQ) with its electron deficient counterpart, benzoquinone (BQ), result in the formation of a quinhydrone charge-transfer complex. Herein, we report a novel quinhydrone-type complex between pillar[5]quinone (P[5]Q) and HQ. Characterized by a suite of spectroscopic techniques including ¹H NMR, UV-visible, and FTIR together with PXRD, SEM, BET, CV, and DFT modeling studies, the stability of the complex is determined to be due to an electron-proton transfer reaction coupled with a complementary donor-acceptor interaction. The selectivity of P[5]Q toward HQ over other dihydroxybenzene isomers allows for not only the naked-eye detection of HQ but also its selective liquid-liquid extraction and recovery from aqueous media.

Cagearenes: synthesis, characterization, and application for programmed vapor release

Here, we announce the establishment of a new family of organic molecular cages, named cagearenes, by taking advantage of a versatile strategy. These cagearenes were prepared via the Friedel–Crafts reaction by condensing two equivalents of a precursor bearing three 1,4-dimethoxybenzene groups and three equivalents of formaldehyde. Two cages, namely cagearene-1 and cagearene-2, are obtained and well characterized. The cagearene-1 solid exhibits the ability to adsorb benzene vapour from an equimolar benzene/cyclohexane mixture with a purity of 91.1%. Then, the adsorbed benzene molecules can be released from the cage at a relatively lower temperature, namely 70 °C, as a consequence of which, cyclohexane with a high purity was left within the cage solid. Heating the cage solid further at 130 °C led to the production of cyclohexane with a purity up to 98.7%. As inferred from the single crystal structures and theoretical calculations, the ability of the cage in programmed release of benzene and cyclohexane results from the different binding modes of these two guests.

Two organic cages, cagearene-1 and cagearene-2, are prepared. The cagearene-1 solid selectively absorbs benzene vapor from a benzene/cyclohexane mixture and is used to achieve temperature-controlled programmed vapor release.

Phenanthrene[2]arene: synthesis and application as nonporous adaptive crystals in the separation of benzene from cyclohexane

Phenanthrene[2]arene 1 with excellent adsorption capacity for benzene was synthesized in high yield. Activated crystals of 1 have been successfully used to separate PhH from equimolar mixture of PhH and Cy and the purity of the PhH can reach 98.4%.

Molecular recognition and adsorptive separation of m-xylene by trianglimine crystals

The separation of xylene isomers is one of the most challenging tasks in the petrochemical industry. Herein, we developed an efficient adsorptive molecular sieving strategy using crystalline trianglimine macrocycle (1) to separate the elusive m-xylene isomer from an equimolar xylenes mixture with over 91% purity. The selectivity is attributed to the capture of the preferred guest with size/shape selectivity and C-H⋯π interactions. Moreover, the trianglimine crystals are readily recyclable due to the reversible transformation between the guest-free and guest-loaded structures.

Macrocyclic Photoinitiator Based on Prism[5]arene Matching LEDs Light with Low Migration

In this work, a naphthalene-based macrocycle prism[5]arene (NP₅ OCH₃ ) is developed as a novel kind of photoinitiator. When NP₅ OCH₃ is irradiated under light, the bond between methylene and naphthalene can be quickly broken owning to the existence of ring tension. The macrocycle is cleaved to linear oligomer biradicals, which can effectively initiate the free radical photopolymerization of acrylate monomers. Compared with conventional photoinitiators, NP₅ OCH₃ has strong light absorption in the wavelength range of 365-405 nm, so it can well match the environment-friendly light-emitting diodes (LEDs) light source to realize highly efficient initiation. In addition, there is no small molecule fragment generated during NP₅ OCH₃ fracture, and the resulted linear oligomer biradicals can be immobilized in the polymer after initiating polymerization, so NP₅ OCH₃ photoinitiators show much lower migration rate and cytotoxicity. Cleavable macrocycle prismarene may provide a new idea for the design of safe and efficient photoinitiators matching long wavelength light.

Dynamics in Flexible Pillar[n]arenes Probed by Solid-State NMR

Pillar[n]arenes are supramolecular assemblies that can perform a range of technologically important molecular separations which are enabled by their molecular flexibility. Here, we probe dynamical behavior by performing a range of variable-temperature solid-state NMR experiments on microcrystalline perethylated pillar[n]arene (n = 5, 6) and the corresponding three pillar[6]arene xylene adducts in the 100-350 K range. This was achieved either by measuring site-selective motional averaged 13C 1H heteronuclear dipolar couplings and subsequently accessing order parameters or by determining 1H and 13C spin-lattice relaxation times and extracting correlation times based on dipolar and/or chemical shift anisotropy relaxation mechanisms. We demonstrate fast motional regimes at room temperature and highlight a significant difference in dynamics between the core of the pillar[n]arenes, the protruding flexible ethoxy groups, and the adsorbed xylene guest. Additionally, unexpected and sizable 13C 1H heteronuclear dipolar couplings for a quaternary carbon were observed for p-xylene adsorbed in pillar[6]arene only, indicating a strong host-guest interaction and establishing the p-xylene location inside the host, confirming structural refinements.

In situ formation of Hg2+-coordinated fluorescent nanoparticles through a supramolecular polymer network used for efficient Hg2+ sensing and separation

There have been many new methods for synthesizing novel nanomaterials with unique functions. Herein, a novel strategy to form fluorescent nanoparticles in situ has been developed, and it can be applied to efficiently sense Hg2+ in living cells and also separate Hg2+ from water.

Weakened Triplet-Triplet Annihilation of Diiodo-BODIPY Moieties without Influence on Their Intrinsic Triplet Lifetimes in Diiodo-BODIPY-Functionalized Pillar[5]arenes

The triplet-triplet annihilation (TTA) effect of sensitizers themselves can lead to the additional quenching of lifetimes of triplet states; therefore, how to weaken the TTA effect of sensitizers is an urgent issue to be resolved for their further applications. Besides, it remains a tremendous challenge for constructing supramolecular systems of photosensitizers based on photosensitizer-functionalized pillararenes because there have been very few investigations on them. Thus, 2,6-diiodo-1,3,5,7-tetramethyl-8-phenyl-4,4-difluoroboradiazaindacene (DIBDP) and ethoxy pillar[5]arene (EtP5) were utilized to synthesize a DIBDP-functionalized pillar[5]arene (EtP5-DIBDP), a cyano-containing DIBDP (G) used as a guest molecule was also prepared, and they were used to investigate the electron-transfer mechanism between EtP5 and DIBDP moieties and weaken the TTA effect of DIBDP moieties. The theoretical computational results of frontier molecular orbitals and isosurfaces of spin density preliminarily predicted that the cavities of the EtP5 moiety had influence on the fluorescence emission of DIBDP units but not on their triplet states in EtP5-DIBDP. The fluorescence emission intensities in a variety of solvents with different polarities and electrochemical studies revealed that there was electron transfer from EtP5 to the DIBDP units, and the electron-transfer process had influence on the fluorescence emission but not on the triplet states of DIBDP moieties in EtP5-DIBDP, which verified the results of density functional theory calculations. The triplet state lifetimes of EtP5-DIBDP were longer than those of DIBDP and G and the photooxidation abilities of EtP5-DIBDP were better than those of DIBDP and G at a high concentration (1.0 × 10^-5 M) in various solvents; in contrast, the intrinsic triplet state lifetimes and singlet oxygen quantum yields (Φ_Δ) of DIBDP, G, and EtP5-DIBDP were very similar. This was because the steric hindrance of EtP5 moieties could weaken the TTA effect of DIBDP moieties without influencing their intrinsic triplet state lifetimes in EtP5-DIBDP.

A supramolecular complex of hydrazide-pillar[5]arene and bisdemethoxycurcumin with potential anti-cancer activity

Pillar[5]arene complexes of the naturally occurring compound bisdemethoxycurcumin (BDMC) were acquired for improving the water solubility and stability of BDMC. As a family member of curcuminoid compounds, BDMC has many interesting therapeutic properties. However, its low aqueous solubility and stability resulted in poor availability and restricted the clinical efficacy. Pillar[5]arenes with hydrophilic ends and a hydrophobic cavity could include with BDMC based on size matching. The synthesized hydrazide-pillar[5]arene (HP5A) and BDMC had a strong host-guest interaction with a 1:1 binding stoichiometry. Furthermore, the HP5A ⊃ BDMC complex could self-assemble into well-defined fibers in water/ethanol solution. This supramolecular complex worked well in vitro for inhibiting the proliferation of hepatoma carcinoma cells HepG2. Remarkably, this method of complexation with pillar[5]arenes visibly reduced the undesirable side effects on normal cells without weakening the anti-cancer activity of the drugs. We expected that the obtained host-guest complex and fibrous assembly would provide a promising platform for delivering drugs with low water solubility.

Dual Emissive Gold(I)-Sulfido Cluster Framework Capable of Benzene-Cyclohexane Separation in the Solid State Accompanied by Luminescence Color Changes

A decanuclear gold(I)-sulfido complex, [(L^H)₄Au₁₀S₄]Cl₂ (L^H-Au₁₀S₄-Cl, where L^H = 4,5-bis(diphenylphosphanyl)-2H-1,2,3-triazole), assembled from the reaction of H₂S with the chlorogold(I) precursor obtained from the click reaction of [dppa(AuCl)₂] (where dppa = 1,2-bis(diphenylphosphino)acetylene) with NaN₃, is shown to display a bright dual green and red emission in the solid state. Single crystal X-ray diffraction (SCXRD) studies indicate a gold(I) cluster-based framework assembled through intermolecular halogen···hydrogen bonds as well as other weak interactions. The framework of L^H-Au₁₀S₄-Cl is found to display high stability toward solvent molecules, with capability to encapsulate solvent molecules, such as benzene and cyclohexane, inside the crystal lattice voids via a single-crystal-to-single-crystal (SCSC) transformation. With different degrees of influence on the dual green and red emission, crystalline solids of L^H-Au₁₀S₄-Cl exhibit remarkable solvatochromic luminescence in the presence of benzene and cyclohexane. Notably, due to the size confinement of the lattice cavities, the L^H-Au₁₀S₄-Cl solids exhibit a high selectivity (>95%) toward benzene in a mixture of equimolar concentration of benzene and cyclohexane. This work has demonstrated the promising capability of gold(I)-sulfido cluster frameworks to serve as luminescent functional materials for the separation of benzene and cyclohexane.

Highly Selective Separation of Isopropylbenzene and α-Methylstyrene by Nonporous Adaptive Crystals of Perbromoethylated Pillararene via Vapor- and Liquid-Phase Adsorptions

Isopropylbenzene (IPB) and α-methylstyrene (AMS), two members of C9 aromatics, are important in both industrial production and laboratory research, but the separation of IPB/AMS mixtures is still a big challenge. Here, we provide a new strategy to separate IPB and AMS using nonporous adaptive crystals of four pillararenes, perethylated pillar[5]arene, perethylated pillar[6]arene, perbromoethylated pillar[5]arene, and perbromoethylated pillar[6]arene (BrP6). Among them, BrP6 selectively adsorbs IPB from an equal volume mixture of IPB and AMS with >95% purity for solid-vapor phase adsorption and >94% purity for solid-liquid phase adsorption, while the selectivities for the other three pillararenes are unsatisfactory. Single-crystal structural analyses combined with powder X-ray diffraction and differential scanning calorimetry experiments demonstrate that the selectivity arises from the different stabilities of guest-loaded BrP6 crystals. Moreover, the reversible transitions between guest-free and IPB-loaded structures indicate the preeminent recycling performance of BrP6 crystals.

Supramolecular cancer nanotheranostics

Among the many challenges in medicine, the treatment and cure of cancer remains an outstanding goal given the complexity and diversity of the disease. Nanotheranostics, the integration of therapy and diagnosis in nanoformulations, is the next generation of personalized medicine to meet the challenges in precise cancer diagnosis, rational management and effective therapy, aiming to significantly increase the survival rate and improve the life quality of cancer patients. Different from most conventional platforms with unsatisfactory theranostic capabilities, supramolecular cancer nanotheranostics have unparalleled advantages in early-stage diagnosis and personal therapy, showing promising potential in clinical translations and applications. In this review, we summarize the progress of supramolecular cancer nanotheranostics and provide guidance for designing new targeted supramolecular theranostic agents. Based on extensive state-of-the-art research, our review will provide the existing and new researchers a foundation from which to advance supramolecular cancer nanotheranostics and promote translationally clinical applications.

Guest-Binding-Induced Interhetero Hosts Charge Transfer Crystallization: Selective Coloration of Commonly Used Organic Solvents

Unprecedented interheteromacrocyclic hosts charge transfer (CT) crystals were generated by cooling organic solutions containing p-dimethoxybenzene-constituted pillar[5]arene (P5A) and p-benzoquinone-constituted pillar[5]quinone (P5Q). Despite the weak CT interaction known between p-dimethoxybenzene and p-benzoquinone and the lack of formation of CT complexes between P5A and P5Q in the solution phase, CT cocrystals between P5A and P5Q were formed with solvent molecules included into the hosts' cavities. Such a cocrystallization arises from an elegant synergy between the CT interaction and solvent-binding-promoted crystallization. The interhetero hosts CT crystals were studied by optical and electron microscopic techniques, X-ray powder diffraction, solid-state NMR, UV-vis, IR spectroscopic studies, and X-ray single-crystal studies. The solvent complexation was critical for formation of the supramolecular CT microcrystals. The CT absorption bands faded upon removing the solvent molecules under vacuum, but they could be recovered by reuptake of the solvent molecules. Intriguingly, the CT absorption bands and uptake kinetics are distinguishably different for various organic solvents, thus providing a unique way to distinguish between different commonly used chemicals.

Concentration-dependent supramolecular self-assembly of A1/A2-asymmetric-difunctionalized pillar[5]arene

A series of A1/A2-bromoalkoxy-and-hydroxy-difunctionalized pillar[5]arenes were synthesized by the removal of the pillar[5]arene-bearing benzyl group using catalytic hydrogenation. The difunctionalized pillar[5]arene bearing 8-bromooctoxy and benzyloxy substituents at the A1/A2 positions formed pseudo[1]rotaxane at low concentration and double-threaded supramolecular dimer at high concentration. The supramolecular self-assembly behavior has been probed with multiple methods including varying (variable) concentration 1H NMR spectroscopy, diffusion-ordered spectroscopy (DOSY), dynamic light scattering (DLS) measurements, isothermal titration calorimetry (ITC), and single-crystal X-ray analysis.

Intrinsically Porous Molecular Materials (IPMs) for Natural Gas and Benzene Derivatives Separations

ConspectusSeparating and purifying chemicals without heat would go a long way toward reducing the overall energy consumption and the harmful environmental footprint of the process. Molecular separation processes are critical for the production of raw materials, commodity chemicals, and specialty fuels. Over 50% of the energy used in the production of these materials is spent on separation and purification processes, which primarily includes vacuum and cryogenic distillations. Chemical manufacturers are now investigating modest thermal approaches, such as membranes and adsorbent materials, as they are more cognizant than ever of the need to save energy and prevent pollution. Porous materials, such as zeolites, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs), have dominated the field of industrial separations as their high surface areas and robust pores make them ideal candidates for molecular separations of gases and hydrocarbons. Separation processes involving porous materials can save 70%-90% of energy costs compared to that of thermally driven distillations. However, most porous materials have low thermal, chemical, and moisture stability, in addition to limited solution processability, which tremendously constrain their broad industrial translation. Intrinsically porous molecular materials (IPMs) are a subclass of porous molecular materials that are comprised of molecular host macrocycles or cages that absorb guests in or around their intrinsic cavity. IPMs range from discrete porous molecules to assemblies with amorphous or highly crystalline structures that are held together by weak supramolecular interactions. Compared to the coordination or dynamic covalent bond-constructed porous frameworks, IPMs possess high thermal, chemical, and moisture stability and maintain their porosity under critical conditions. Moreover, the intrinsic porosity endows IPMs with excellent host-guest properties in solid, liquid (organic or aqueous), and gas states, which can be further utilized to construct diverse separation strategies, such as solid-gas adsorption, solid-liquid absorption, and liquid-liquid extraction. The diversity of host-guest interactions in the engineered IPMs affords a plethora of possibilities for the development of the ideal "molecular sieves". Herein, we present a different take on the applicability of intrinsically porous materials such as cyclodextrin (CD), cucurbiturils (CB), pillararene (P), trianglamines (T), and porous organic cages (POCs) that showed an impressive performance in gas purification and benzene derivatives separation. IPMs can be easily scaled up and are quite stable and solution processable that consequently facilitates a favorable technological transformation from the traditional energy-intensive separations. We will account for the main advances in molecular host-guest chemistry to design "on-demand" separation processes and also outline future challenges and opportunities for this promising technology.

Guest-dependent single-crystal-to-single-crystal transformations in porous adamantane-bearing macrocycles

An adamantane-bearing macrocycle exhibited permanent intrinsic porosity and adsorption of small guests in single-crystal-to-single-crystal fashions. The guest capture resulted in the structural transformations of supramolecular organic frameworks.

Selective complexation and efficient separation of cis/trans-1,2-dichloroethene isomers by a pillar[5]arene

The complexation and separation of industrially important cis- and trans-1,2-dichloroethene (cis- and trans-DCE) isomers using perethylated pillar[5]arene (EtP5) are described. EtP5 exhibits considerable binding capability for the trans-DCE isomer over the cis-DCE in organic solution. Furthermore, nonporous adaptive crystals (NACs) of EtP5 can efficiently separate trans-DCE from a 50 : 50 (v/v) cis/trans-isomer mixture.