Search Results (142)

Cyclodextrins (CDs), cyclic oligosaccharides formed by α-1,4-glycosidic-bonded D-glucopyranose units, feature unique hydrophobic cavities and hydrophilic exteriors that enable molecular encapsulation via host–guest interactions. CDs form supramolecular host–guest complexes with diverse molecular entities, establishing their fundamental role in supramolecular chemistry. This review examines fabrication strategies for CD-based supramolecular hydrogels and their applications in tissue engineering and regenerative medicine, with focused analysis on wound healing, corneal regeneration, and bone repair. We critically analyze CD–guest molecular interaction mechanisms and innovative therapeutic implementations, highlighting the significant potential of CD hydrogels for tissue regeneration while addressing clinical translation challenges and future directions. Full article

The cationic chloro-P-{[4-(diphenylphosphanyl)phenyl]-N,N-dimethylmethanammonio(norbornadiene)rhodium(I) complex was encapsulated inside a self-assembled hexameric capsule. This capsule was obtained through a reaction involving 2,8,14,20-tetra-undecyl-resorcin[4]arene and water in chloroform. The formation of an inclusion complex was deduced from a combination of spectral measurements (UV-visible spectroscopy, ¹H, ³¹P{¹H} NMR and DOSY). The rhodium complex was evaluated in the [2+2+2] cycloaddition between N,N-dipropargyl-p-toluenesulfonamide and arylacetylene derivatives. In the presence of two equivalents of arylacetylenes in water-saturated chloroform at 60 °C for 24 h, the 4-methyl-N-(prop-2-yn-1-yl)-N-((2-tosylisoindolin-5-yl)methyl)benzenesulfonamide, the homocycloaddition product of 1,6-diyne is predominantly formed. In the presence of the supramolecular capsule, a selectivity inversion in favor of 5-aryl-2-tosylisoindoline is observed, with heterocycloaddition products formed in proportions between 53 and 69%. Full article

The interaction between cucurbit[8]uril (Q[8]) and the guest 1-methyl-4-(4-(1-methylpyridin-1-ium-4-yl)benzamido)pyridin-1-ium (PB²⁺) has been thoroughly investigated. Multiple techniques were employed, including ¹H NMR spectroscopy, mass spectrometry, isothermal titration calorimetry (ITC), UV–vis absorption spectrophotometry, and quantum chemistry calculations. The experimental results and calculation analysis have clearly shown that in aqueous solution, the host Q[8] preferentially encapsulates the phenylpyridinium salt moiety of the PB²⁺ guest within its hydrophobic cavity, forming a 1:2 inclusion complex. Full article

The [PdCl₂(cod)] complex was encapsulated inside a self-assembled hexameric capsule obtained via a reaction of 2,8,14,20-tetra-undecyl-resorcin[4]arene and water. The formation of an inclusion complex was deduced from a combination of spectral measurements (UV-visible, ¹H NMR and DOSY spectroscopies). The latter proved effective in the dimerization of styrene derivatives under mild conditions, with a catalyst loading of 0.5 mol% at 60 °C. Electronically enriched vinyl arenes underwent cyclization of the catalytic products, leading to the quasi-quantitative formation of indanes from 4-tert-butylstyrene and 9-vinylanthracene. In the instance of 9-vinylanthracene, the rearrangement product is tribenzo–pentaphene, which is formed in 50% of conversions. Full article

This review highlights how advances in silico techniques have shed new light on phenomena in confined supramolecular resorcinarene-based systems. Computational studies have provided detailed insights into capsule formation, their dynamic behavior, guest encapsulation and reaction mechanisms within these hosts, often revealing information that experimental methods cannot reach. The focus is placed on the self-assembly of resorcin[4]arenes, pyrogallol[4]arenes, velcrands, and octa acid systems. These computational studies complement experimental findings and, in many cases, offer new perspectives that are inaccessible using experimental techniques alone. Supramolecular architectures are growing in complexity the role of in silico approaches is becoming indispensable. They offer a way to design rationally and understand host–guest chemistry more deeply. Full article

The second-generation phosphorescent organic light-emitting diodes are formed using phosphorescent emitters, which can theoretically achieve 100% internal quantum efficiency. However, these emitting materials usually suffer from triplet–triplet annihilation (TTA) and/or concentration-quenching effects. To address the disadvantages, host–guest systems are used in the emitting layer, where the guest is dispersed into a host matrix. Carbazole is one of the most commonly used electron-donating fragments, which is widely applied as a building block for the synthesis of the mentioned host materials. In this review article, we describe the synthesis, thermal, electrochemical, and optoelectronic properties of the hosts with carbazolyl units as well as application of the matrixes in the phosphorescent devices. This review is written from the perspective of structural chemistry and the host materials are divided in several groups as 9-arylcarbazoles, twin derivatives containing two carbazolyl fragments, 3(2)-aryl(arylamino)-substituted, and 3,6(2,7)-diaryl(diarylamino)-substituted carbazoles. Full article

Aflatoxin B1 (AFB1), a highly toxic secondary metabolite produced by Aspergillus species, represents a significant health hazard due to its widespread contamination of agricultural products. The urgent need for sensitive and sustainable detection methods has driven the development of diverse analytical approaches, most of which heavily rely on organic solvents, posing environmental challenges for routine food safety analysis. Here, we introduce a supramolecular platform leveraging acyclic cucurbit[n]uril (acCB) as a host molecule for environmentally sustainable AFB1 detection. Screening various acCB derivatives identified acCB6 as a superior host capable of forming a stable 1:1 complex with AFB1 in an aqueous solution, exhibiting a high binding affinity. Proton nuclear magnetic resonance (1H NMR) spectroscopy confirmed that AFB1 was deeply encapsulated within the host cavity, with isothermal titration calorimetry (ITC) experiments and molecular dynamics simulations further substantiating the stability of the interaction, driven by enthalpic and entropic contributions. This supramolecular host was incorporated into a scaffold-assembly-based bioluminescent enzyme immunoassay (SA-BLEIA), providing a green detection platform that rivals the performance of traditional organic solvent-based assays. Our findings highlight the potential of supramolecular chemistry as a foundation for eco-friendly mycotoxin detection and offer valuable insights into designing environmentally sustainable analytical methods. Full article

Cyclodextrins can serve as carriers for various payloads, utilizing their capacity to form unique host–guest inclusion complexes within their cavity and their versatile surface functionalization. Recently, cationic cyclodextrins have gained considerable attention, as they can improve drug permeability across negatively charged cell membranes and efficiently condense negatively charged nucleic acid due to electrostatic interactions. This review focuses on state-of-the-art and recent advances in the construction of cationic cyclodextrin-based delivery systems. First, we identified different cationic moieties that are commonly employed in the design of cyclodextrins with enhanced complexation ability. Subsequently, a wide range of cationic cyclodextrin-based drug delivery systems were analyzed with emphasis on chemistry, drug release profiles, and therapeutic outcomes. The evaluation of the delivery platforms was also based on the four major types of drugs, such as anticancer, anti-inflammatory, antibacterial, and antidiabetic agents. The delivery systems for nucleic acids were also summarized while focusing on their condensation ability, transfection efficiency, and biocompatibility in comparison to commercially available vectors such as PEI 25 kDa and lipofectamine 2000. Furthermore, we highlighted the potential of cationic cyclodextrins in constructing multimodal delivery systems for the simultaneous encapsulation of both drugs and nucleic acids. Finally, the challenges and limitations associated with cationic cyclodextrin setups were discussed. Full article

Cisplatin (DDP), a platinum-chelated compound renowned for its antitumor activity, is often utilized in cancer therapy. However, its real-world clinical efficacy is compromised by poor solubility and low stability, which impedes wider clinical application. Our study aimed to address these limitations of DDP through host–guest supramolecular chemistry approaches. We explored the potential of 18-crown-6 as the host molecule to solubilize and stabilize DDP, the guest molecule. Utilizing techniques such as UV–visible spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and molecular docking, we conducted a comprehensive analysis on the physical state and inclusion mode of the DDP@18-crown-6 complex. Phase solubility studies and Job’s plot confirmed that the DDP@18-crown-6 complex significantly enhanced the aqueous solubility of DDP, with an optimal 1:1 binding ratio. Stability analyses revealed that this complex markedly improved the stability of DDP in pure water. Meanwhile, the stabilization effects of DDP@18-crown-6 were remarkably elevated when combined with 0.9% sodium chloride. In vitro antitumor assays in A549 cell lines demonstrated that the DDP@18-crown-6 complex outperformed raw DDP in cytotoxicity, showing a significantly lower IC₅₀ value. This research offered a promising strategy for DDP solubilization and stabilization, facilitating its anticancer therapeutic efficacy. Full article

The advancement of synthetic host–guest chemistry has played a pivotal role in exploring and quantifying weak non-covalent interactions, unraveling the intricacies of molecular recognition in both chemical and biological systems. Macrocycles, particularly calix[4]resorcinarene-based cavitands, have demonstrated significant utility in receptor design, facilitating the creation of intricately organized architectures. Within the realm of macrocycles, these cavitands stand out as privileged scaffolds owing to their synthetic adaptability, excellent topological structures, and unique recognition properties. So far, extensive investigations have been conducted on various applications of calix[4]resorcinarene-based cavitands. In this review, we will elaborate on their diverse functions, including catalysis, separation and purification, polymeric materials, sensing, battery materials, as well as drug delivery. This review aims to provide a holistic understanding of the multifaceted roles of calix[4]resorcinarene-based cavitands across various applications, shedding light on their contributions to advancing the field of supramolecular chemistry. Full article

Molecular cages have promising host–guest properties for drug delivery applications. Specifically, guest⊂cage complexes can be used for the on-command release of encapsulated guest molecules in response to specific stimuli. This research explores both the dynamic and constrictive binding guest⊂cage systems for drug encapsulation and release in biological environments. In dynamic systems, the guest rapidly passes in-and-out through the portals of the cage, enabling drug delivery in vitro but facing limitations in vivo due to dilution effects that result in guest release. These challenges are addressed by constrictive binding systems, where the guest is trapped in a “gate-closed” state within the cage. In these systems, the on-command release is triggered by a “gate opening” event, which lowers the guest–out energy barrier. A full guest release is achieved when the gate opening reduces the cage–guest affinity, making constrictive binding systems more effective for controlled drug delivery. As a result, this study shows that guest⊂cage complexes have suitable properties for drug delivery in biological contexts. Full article

In addition to the course of over 20 years of cucurbit-7-uril (CB[7]) in the pharmaceutical industry, the present study brings together the most recent observations from the perspective of ultrasensitive Raman spectroscopy and Density Functional Theory (DFT) related to the interaction of this molecule with atenolol (Ate) enantiomers during the formation of these host–guest complexes. Quantum chemistry calculations based on DFT were first used to understand the interaction geometry between CB[7] and Ate. These results were further confirmed by ultrasensitive vibrational spectroscopy. The spectral features associated with each enantiomer in the presence of CB[7] were analyzed by means of SERS, highlighting distinct interaction profiles. These experimental findings validated quantum chemical calculations, offering a comprehensive understanding of the host–guest interactions at the nanoscale level. Full article

Amperometric electrochemical sensing schemes, which are easily fabricated and can directly relate measured current with analyte concentrations, remain a promising strategy for the development of the portable, in situ detection of commonly employed adulterants. Xylazine (XYL) is a non-narcotic compound designed for veterinary use as a sedative known as Rompun^®. XYL is increasingly being abused as a recreational drug, as an opioid adulterant and, because of its chemical properties, has found unfortunate prominence as a date rape drug spiked into beverages. In this study, a systematic exploration and development of fouling-resistant, amperometric XYL sensors is presented. The sensing strategy features layer-by-layer (LBL) modification of glassy carbon electrodes (GCEs) with carbon nanotubes (CNTs) for sensitivity and the engagement of cyclodextrin host–guest chemistry in conjunction with polyurethane (PU) semi-permeable membranes for selectivity. The optimization of different materials and parameters during development created a greater fundamental understanding of the interfacial electrochemistry, allowing for a more informed subsequent design of effective sensors exhibiting XYL selectivity, effective sensitivity, rapid response times (<20 s), and low estimated limits of detection (~1 ppm). Most importantly, the demonstrated XYL sensors are versatile and robust, easily fabricated from common materials, and can effectively detect XYL at <10 ppm in both common alcoholic and non-alcoholic beverages, requiring only minimal volume (20 µL) of the spiked beverage for a standard addition analysis. Full article

The crystalline sponge method has proven invaluable in the preparation and analysis of supramolecular host/guest complexes if the host can be obtained in a suitable crystalline form, allowing the analysis of guest binding modes inside host cavities which can inform other studies into processes such as catalysis. Here, we report the structures of a set of ten host/guest complexes using an octanuclear coordination cage host with a range of small-molecule neutral organic guests including four aromatic aldehydes and ketones, three cyclic lactams, and three epoxides. In all cases, the cavity-bound guests are anchored by a collection of CH•••O hydrogen-bonding interactions between an O atom on the guest and a convergent set of CH protons at a pocket on the cage interior surface. Depending on guest size and the presence of solvent molecules as additional guests, there may be one or two cavity-bound guests, with small aromatic guests forming π-stacked pairs. Some guests (the lactams) participate in additional NH•••F H-bonding interactions with surface-bound fluoroborate anions, which indicate the type of anion/guest interactions thought to be responsible for solution-phase catalytic reactions of bound guests. Full article

Herein, we study the London dispersion forces between organic structure directing agents (OSDAs)—here tetraalkyl-ammonium or -phosphonium molecules—and silica zeolite frameworks (FWs). We demonstrate that the interaction energy for these dispersion forces is correlated to the number of H atoms in OSDAs, irrespective of the structures of OSDAs or FWs, and of variations in charges and thermal motions. All calculations considered—DFT-D3 and BOMD undertaken by us, and molecular mechanics from an accessible database—led to the same trend. The mean energy of these dispersion forces is ca. −2 kcal.mol⁻¹ per H for efficient H-O contacts. Full article