Assembly and Applications of Macrocyclic-Confinement-Derived Supramolecular Organic Luminescent Emissions from Cucurbiturils

Recent advances in smart hydrogels derived from polysaccharides and their applications for wound dressing and healing

Owing to their inherent biocompatibility and biodegradability, hydrogels derived from polysaccharides have emerged as promising candidates for wound management. However, the complex nature of wound healing often requires the development of smart hydrogels---intelligent materials capable of responding dynamically to specific physical or chemical stimuli. Over the past decade, an increasing number of stimuli-responsive polysaccharide-based hydrogels have been developed to treat various types of wounds. While a range of hydrogel types and their versatile functions for wound management have been discussed in the literature, there is still a need for a review of the crosslinking strategies used to create smart hydrogels from polysaccharides. This review provides a comprehensive overview of how stimuli-responsive hydrogels can be designed and made using five key polysaccharides: chitosan, hyaluronic acid, alginate, dextran, and cellulose. Various methods, such as chemical crosslinking, dynamic crosslinking, and physical crosslinking, which are used to form networks within these hydrogels, ultimately determine their ability to respond to stimuli, have been explored. This article further looks at different polysaccharide-based hydrogel wound dressings that can respond to factors such as reactive oxygen species, temperature, pH, glucose, light, and ultrasound in the wound environment and discusses how these responses can enhance wound healing. Finally, this review provides insights into how stimuli-responsive polysaccharide-based hydrogels can be developed further as advanced wound dressings in the future.

Supramolecular Nanoplatform for Biofilm Eradication and Anti-inflammatory by Phototherapies and Macrophage Repolarization

Biofilm dispersion and persistent inflammation are key challenges in treating bacterial infections. Phototherapies, including photodynamic therapy (PDT) and photothermal therapy (PTT), have emerged as promising approaches for treating bacterial infections. However, several challenges continue to impede the treatment effectiveness, particularly, the inevitable inflammatory side effects. Herein, a supramolecular nanoplatform (R-AuSTP-Be) is developed for precise targeting to bacterial infection sites, effective antimicrobial and anti-inflammatory for infected wound healing. R-AuSTP-Be can neutralize bacterial exotoxins for remodeling bacteria microenvironment, and disperse biofilms by precise phototherapies with dual-mode bacteria targeting by glycoprotein covalent bonding and electrostatic attraction. Meanwhile, R-AuSTP-Be reshapes the inflammatory environment by down-regulating M1 macrophage expression and up-regulating M2 macrophage expression. The excellent antibacterial and anti-inflammatory effects of R-AuSTP-Be provide a competitive strategy for treating bacterial infectious diseases.

Recent advances in dopant-matrix afterglow systems: high-performance organic afterglow materials and the critical role of organic matrices in materials fabrication

Organic afterglow materials have garnered significant attention due to their long-lived excited states, demonstrating promising applications across diverse fields. Over the past few decades, these materials have experienced rapid development, particularly dopant-matrix systems. This review focuses on the progress made in dopant-matrix organic afterglow materials over the past three years, emphasizing two key aspects: high-performance organic afterglow materials and the critical role of organic matrices in materials fabrication. In the first section, we summarize strategies for enhancing afterglow performance through molecular design, focusing on representative luminescent systems such as benzophenone derivatives, polycyclic aromatic hydrocarbons, and difluoroboron β-diketonate compounds. The second section explores the pivotal functions of organic matrices, including protecting triplet excited states, facilitating intersystem crossing, sensitizing triplet states, and promoting charge separation, which collectively contribute to novel functionalities of afterglow materials. Beyond the molecular design of luminophores, the selection of organic matrices is equally crucial for achieving high-performance afterglow materials and expanding their functionality. This review provides a comprehensive compilation of chemical structures for various organic matrices, serving as a valuable reference for researchers. Given the intricate photophysical processes in organic afterglow systems, we also present experimental methods that support or refute specific mechanisms, providing critical insights for future studies. Overall, dopant-matrix organic afterglow materials represent a highly promising class of luminescent materials. We anticipate their large-scale adoption and high-value applications in real-world scenarios in the near future.

Thin-film composite vapor-gap membrane for pressure-driven distillation

Pressure-driven distillation (PD), as an emerging technology, holds tremendous potential for producing freshwater from nontraditional water sources. In this process, a sufficient hydraulic pressure is applied to drive water evaporation and vapor transport across a vapor-gap membrane. The development of the PD process critically depends on the availability of robust and large-area superhydrophobic membranes. Here, we propose an ultraselective superhydrophobic thin-film composite (TFC) vapor-gap membrane with confined transport channels toward the PD process, which can be manufactured scale-up through a facile swelling-assisted deposition strategy. The TFC-PD membrane demonstrates separation capabilities, achieving near-complete rejections of nonvolatile solutes, including salts, boron, and urea. Featured by a vapor-gap superhydrophobic layer, the TFC-PD membrane exhibits superior chlorine and scaling resistance and maintains stable performance over time without being oxidized or scaling. This work offers notable advancements in the microstructural design of PD membranes and the development of scalable robust TFC membranes for the PD process.

Boosting Reaction Kinetics with Viscous Nanowire Dispersions

Higher viscosity typically slows chemical reactions by restricting molecular movement, while stirring accelerates reactions by enhancing reactant diffusion and collisions. However, in this study, we reveal that reaction rates in nanowire dispersions─with microscopic viscosity ∼300 times that of decane, can be enhanced by over an order of magnitude. Counterintuitively, stirring slows the reaction with higher stirring rates causing even greater deceleration. This phenomenon is observed in both photo- and thermally activated cyclic reactions. Molecular dynamics simulations and confocal laser scanning microscopy suggest that aliphatic chains grafted onto nanowires interact with anisotropic molecules, increasing their local concentrations near the nanowires. Notably, azobenzene photoisomerization is completely inhibited in the nanowire dispersion, despite completing within 30 s in the absence of nanowires. We propose that the aliphatic chains align reactive molecules directionally, while the confined space prevents bulky cis-isomer formation. These findings show that nanowires not only harvest and orient reactive molecules but also exclude bulky products, significantly enhancing the reaction kinetics in confined systems.

Supramolecular Self-Assembly and Metal-Ligand-Enhanced Organic Room-Temperature Phosphorescence for Live Cell Imaging

A purely organic supramolecular assembly emitting room-temperature phosphorescence (RTP) was constructed from 1-(3-(bis(pyridin-2-ylmethyl)amino)propyl)-4-(4-bromophenyl)pyridin-1-ium bromide (BP-DPA) by complexing with cucurbit[8]uril (Q[8]) and Zn2+ through a supramolecular assembly. Benefiting from the strong affinity and the macrocyclic restriction effect of Q[8], phosphorescence emission was achieved by encapsulating BP-DPA in the Q[8] cavity. Notably, secondary assembly with Zn2+ formed the supramolecular complex BP-DPA@Q[8]⊂Zn2+, which greatly contributed to the enhancement of the phosphorescence quantum yield and lifetime from 1.75% to 6.25% and from 0.48 to 1.25 ms, respectively. Meanwhile, BP-DPA@Q[8] specifically recognizes Zn2+ with a low detection limit without interference from common metal ions, anions, and biomolecules. It permeates the plasma membrane of cells and emits a specific phosphorescence response signal in the presence of Zn2+. In addition, this material can also be utilized for the development of portable indicator papers, enabling the rapid and visualized detection of Zn2+. This work provides a route for constructing multilevel supramolecular assemblies of RTP, extending the biological applications of purely organic RTP materials and offering additional possibilities for the potential utilization of cucurbit[n]uril-based room-temperature phosphorescence materials.

Supramolecular phosphorescent assemblies based on cucurbit[8]uril and bromophenylpyridine derivatives for dazomet recognition

A bromophenylpyridine derivative (N1) was designed, synthesized, and the molecule was incorporated into the cavity of the cucurbit[8]uril (Q[8]) as a guest to form a 2:1 host-guest complex. This complex demonstrates good room temperature phosphorescence (RTP) properties in aqueous solution. The host-guest interaction and optical properties of N1@Q[8] in aqueous solution were studied by means of 1H NMR, ultraviolet-visible absorption spectroscopy, fluorescence spectroscopy, phosphorescence spectroscopy, scanning electron microscopy and inverted fluorescence microscopy. The results show that the bromophenyl part of the guest molecule enters the cavity of Q[8], while the other part of N1 remains outside the cavity, resulting in a 2:1 supramolecular structure. This assembly exhibits specific recognition of dazomet on the phosphorescence spectrum with a detection limit of 8.8329 × 10-7 mol·L-1. Collectively, this finding opens up a new possibility for the potential application of room temperature phosphorescent materials in analytical detection.

Precise Control of Noncovalent Dimerization via Cucurbit[n]uril-Based Host-Guest Complexation

Upon complexation between differently sized cucurbit[n]uril (n = 7, 8, or 10) hosts and a fluorenone derivative with various binding modes, the aggregation state of the fluorenone guest is precisely switched from J-aggregates to the monomer, H-dimer, and separated "H-dimer", thus enabling the construction of multicolor luminescent materials in an aqueous solution.

Functional crystalline porous framework materials based on supramolecular macrocycles

Crystalline porous framework materials like metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) possess periodic extended structures, high porosity, tunability and designability, making them good candidates for sensing, catalysis, gas adsorption, separation, etc. Despite their many advantages, there are still problems affecting their applicability. For example, most of them lack specific recognition sites for guest uptake. Supramolecular macrocycles are typical hosts for guest uptake in solution. Macrocycle-based crystalline porous framework materials, in which macrocycles are incorporated into framework materials, are growing into an emerging area as they combine reticular chemistry and supramolecular chemistry. Organic building blocks which incorporate macrocycles endow the framework materials with guest recognition sites in the solid state through supramolecular interactions. Distinct from solution-state molecular recognition, the complexation in the solid state is ordered and structurally achievable. This allows for determination of the mechanism of molecular recognition through noncovalent interactions while that of the traditional recognition in solution is ambiguous. Furthermore, crystalline porous framework materials in the solid state are well-defined and recyclable, and can realize what is impossible in solution. In this review, we summarize the progress of the incorporation of macrocycles into functional crystalline porous frameworks (i.e., MOFs and COFs) for their solid state applications such as molecular recognition, chiral separation and catalysis. We focus on the design and synthesis of organic building blocks with macrocycles, and then illustrate the applications of framework materials with macrocycles. Finally, we propose the future directions of macrocycle-based framework materials as reliable carriers for specific molecular recognition, as well as guiding the crystalline porous frameworks with their chemistry, applications and commercialization.

Fluorometric detection and analog discrimination of melatonin by amide naphthotube-based indicator displacement assays

Melatonin, a hormone synthesized by the pineal gland, is renowned for its pivotal role in governing circadian rhythms and its promising therapeutic attributes encompassing anti-inflammatory, anti-aging, and cancer-preventative properties. Nevertheless, the improper utilization of melatonin may lead to health hazards, highlighting the critical necessity for accurate detection of melatonin in pharmaceutical or biological samples. Furthermore, melatonin metabolites exhibit analogous chemical structures yet divergent pathophysiological functions, emphasizing the significance of distinguishing between these analogs. In this study, we report a supramolecular sensor that combines amide naphthotube and toluidine blue O in an indicator displacement assay for the quantitative detection of melatonin and differentiation of its analogs. The sensor demonstrated remarkable sensitivity, with a low detection limit of approximately 0.70 μM, and a broad dynamic range of 0.70-98.8 μM, along with excellent selectivity and stability. Notably, the sensor enables the determination of melatonin levels in various sample matrices, including milk, artificial urine, and pharmaceutical preparations. Through optimization of the host-guest complex ratio, our newly designed sensor effectively distinguishes melatonin from its six analogs. This approach addresses a current research gap, as existing macrocycles have limited capability to differentiate between melatonin analogs, with only a few achieving precise melatonin quantification.

Enantioselective construction of inherently chiral pillar[5]arenes via palladium-catalysed Suzuki-Miyaura cross-coupling

Pillar[n]arenes have broad applications in biological medicine, materials science, and supramolecular gels. Notably, enantiopure pillar[5]arenes are valued for their roles in enantioselective host-guest recognition, chiral sensing, asymmetric catalysis, and related fields. Current methods for obtaining chiral pillar[n]arenes rely heavily on resolution agents or chiral HPLC resolution. However, the synthesis of these compounds via asymmetric catalysis remains challenging. In this study, we develop an asymmetric extended side-arm Suzuki-Miyaura cross-coupling strategy to construct inherently chiral pillar[5]arenes with excellent yields and high enantioselectivities using a palladium catalyst and a Sadphos ligand. The reaction scope extends beyond arylboronic acids to encompass 2-arylvinylboronic acids and other multi-OTf-substituted substrates, all efficiently producing the desired products. Further exploration of the synthetic applications, along with photophysical and chiroptical analyses, confirm the potential of these chiral pillar[5]arenes for diverse applications across multiple disciplines.

Hour-Long Afterglow in Flexible Polymeric Materials through the Introduction of Electron Donor/Acceptor Exciplexes

The development of organic afterglow materials has garnered significant attention due to their diverse applications in smart devices, optoelectronics, and bioimaging. However, polymeric afterglow materials often suffer from short emission lifetimes, typically ranging from milliseconds to seconds, posing a significant challenge for achieving hour-long afterglow (HLA) polymers. This study presents the successful fabrication of transparent HLA polymers by introducing electron donor/acceptor exciplexes. Employing aromatic polyesters as the polymer electron acceptor and charge reservoirs, the resulting HLA polymers exhibited a remarkable green afterglow that persisted for 12 hours under ambient conditions, representing the longest duration achieved for polymeric afterglow materials to date. Intriguingly, these HLA polymers could be activated solely by sunlight, maintaining a green afterglow for over 6 hours at room temperature in air, which outperformed all previously reported afterglow polymers. The doped polymers exhibited superior flexibility and transparency, making them ideal candidates for flexible display applications. Furthermore, successfully spinning these doped polymers into fibers while retaining their HLA properties opens up exciting possibilities for their use in wearable smart devices.

Cucurbit[8]Uril-Stabilized Charge Transfer: An Efficient Supramolecular Approach Toward a Heterogeneous Organic Photocatalyst for Aerobic Oxidation Reactions

Host-stabilized charge transfer (HSCT) has been widely utilized in macrocycle-derived supramolecular assemblies and architectures. However, there has been less research attention focused on the direct fabrication of pure organic photocatalysts using HSCT. Herein, four viologen derivatives (m-PV2+, m-BPV2+, d-PV2+, and d-BPV2+) with different electron donor-acceptor (D-A) structures were synthesized. Their host-guest complexes with cucurbit[8]uril (Q[8]) in an aqueous solution could be switched using the substituted electron donor moieties, in which the host-guest complexes of m-BPV2+@Q[8] and d-BPV2+@Q[8] exhibited HSCT interactions. Control experiments revealed that the d-BPV2+@Q[8] complex had the strongest ability to sensitize singlet oxygen (1O2). This was ascribed to the increased π-conjugation of d-BPV2+@Q[8], which led to more effective HSCT upon encapsulation by the Q[8] host. Consequently, the d-BPV2+@Q[8] complex could be easily employed as a heterogeneous photocatalyst for the photooxidation reaction of thioether com-pounds with high selectivity. In particular, d-BPV2+@Q[8] was successfully applied to the synthesis of sulfoxide drugs, such as the con-version of inexpensive Iberverin ($7.0 per gram) to the expensive bioactive inhibitor Iberin ($19500.0 per gram) in high yield (94 %).

Fluorinated Macrocycle for Adsorptive Separation and Chromatographic Separation of Toluene and Methylcyclohexane

Achieving the adsorptive separation and chromatographic separation of industrially the important chemicals toluene and methylcyclohexane using the same material is a highly desirable goal. We have successfully accomplished this using a fluorinated macrocycle tetrafluoroterphen[3]arene (4FTP3), which was synthesized and used for gas chromatographic separation in our previous work. The macrocycle 4FTP3 permitted the adsorptive separation of toluene from a toluene/methylcyclohexane mixture (1 : 1, v/v) with a purity of 99.3 % in a single adsorption cycle. Additionally, the use of 4FTP3 as a gas chromatographic stationary phase permitted the high-resolution separation of a toluene/methylcyclohexane mixture, with a retention capacity decreasing in the order of: toluene>methylcyclohexane. Single-crystal structural analysis revealed that the C-H⋅⋅⋅F interactions between 4FTP3 and toluene resulted in an enhanced binding affinity, association enthalpy, and longer retention time for toluene. This macrocycle is of particular interest for use as a separation material due to its simultaneous adsorptive separation and gas chromatographic separation of toluene/methylcyclohexane. The present fluorinated macrocycle may therefore have roles to play in both analytical science and the chemical industry.

Engineering perfluoroarenes for enhanced molecular barrier effect and chirality transfer in solutions

Noncovalent forces have a significant impact on photophysical properties, and the flexible employment of weak forces facilitates the design of novel luminescent materials with a variety of applications. The arene-perfluoroarene (AP) force, as one type of π-hole/π interaction, shows unique directionality, involving an electron-deficient π-hole interacting with a π-electron-rich region, facilitating precise orientation and stabilization in supramolecular structures. Here we present an amination engineering protocol to build a perfluoroarene library based on an octafluoronaphthalene skeleton with various steric and electronic properties. In diluted solution-based assemblies, the perfluoroarenes perform as efficient molecular barriers to perylene building units, lighting up the luminescence. Enhanced steric effects, hydrophobicity and appended aromatic pendants are pivotal structural factors to boost the molecular barrier effect. Highly affinitive AP coassemblies transfer chirality from perfluoroarenes to achiral perylene moieties, inducing the appearance of chiral microstructures with tailored circularly polarized luminescence. Application as luminescent ink for enhanced water-resistance in displays and anti-counterfeiting is successfully realized. This work greatly extends the potential of molecular engineering in noncovalently bonded luminescent materials, and clearly reveals structure-property correlations.

A Supramolecular Fluorescent Chemosensor Enabling Specific and Rapid Quantification of Norepinephrine Dynamics

Host-guest supramolecular fluorescence probes have garnered significant attention in the detection and sensing of bioactive molecules due to their functionalization potential, adjustable physical properties, and high specificity. However, such probes that reliably, rapidly, and specifically measure neurotransmitter dynamics at the cellular and in vivo level have yet to be reported. Herein, we present a supramolecular fluorescent chemosensor designed for norepinephrine (NE) detection, showing an exceptional response and specificity through host-guest complexation. Multiple covalent/noncovalent interactions, molecular-folding, and confinement effect in the system synergistically enhance selectivity and accelerate reaction kinetics down to 190 ms. Our chemosensor enables real-time quantification and imaging of NE across various models including neuronal cytomembranes, brain tissues, and zebrafish. Notably, we successfully monitored NE levels in 26 brain regions of freely moving mice under fear-induced stress, revealing elevated concentrations of NE in these regions associated with emotional processing. Thus, our chemosensor is a robust tool for measuring neurotransmitter dynamics in diverse model organisms.

Near-Infrared Room-Temperature Phosphorescence from Monocyclic Luminophores

Compact luminophores with long emission wavelengths have aroused considerable theoretical and practical interest. Organics with room-temperature phosphorescence (RTP) are also desirable for their longer lifetimes and larger Stokes shifts than fluorescence. Utilizing the low electronic transition energy intrinsic to thiocarbonyl compounds, electron-withdrawing groups were attached to the 4H-pyran-4-thione core to further lower the excited state energies. The resulting mini-phosphors were doped into suitable polymer matrices. These purely organic, amorphous materials emitted near-infrared (NIR) RTP. Having a molar mass of only 162 g mol-1, one of the phosphors emitted RTP that peaked at 750 nm, with a very large Stokes shift of 15485 cm-1 (403 nm). Thanks to the good processability of the polymer film, light-emitting diodes (LEDs) with NIR emission were easily fabricated by coating doped polymer on ultraviolet LEDs. This work provides an intriguing strategy to achieve NIR RTP using compact luminophores.

Cocrystallization-Induced Red Ultralong Organic Phosphorescence

Organic cocrystals formed through multicomponent self-assembly have attracted significant interest owing to their clear structure and tunable optical properties. However, most cocrystal systems suffer from inefficient long-wavelength emission and low phosphorescence efficiency due to strong non-radiative processes governed by the energy gap law. Herein, an efficient long-lived red afterglow is achieved using a pyrene (Py) cocrystal system incorporating a second component (NPYC4) with thermally activated delayed fluorescence (TADF) and ultralong organic phosphorescence (UOP) properties. The cocrystal (NPYC4-Py) not only inherits the excellent luminescence of its monomeric counterparts, but also exhibits unique dual-mode characteristics, including persistent TADF and UOP emission with a high quantum yield of 58 % and a lifetime of 362 ms. The precise cocrystal stacking distinctly reveals that intermolecular interactions lock the cocrystal formation and weaken the intermolecular π-π interactions between NPYC4 and Py, thereby stabilizing the excited triplet excitons. Furthermore, the favorable energy level of NPYC4 acts as a bridge, reducing the energy gap between the S1 and T1 states for Py, therefore activating its red phosphorescence from Py. This research provides direct insights into achieving efficient red UOP through co-crystallization.

A supramolecular diazapyrene radical assembly with NIR absorption for selective photothermal antibacterial activity

A supramolecular radical assembly that can be induced in situ by facultative anaerobic bacteria has been reported and used for selective near-infrared (NIR) photothermal antibacterial action. Herein, we report the synthesis of a water-soluble diazapyrene derivative (DAPNP), which could be in situ initiated into the corresponding radicals by facultative anaerobic bacteria, such as E. coli or S. aureus. The introduction of cucurbit[10]uril (CB[10]) alters the stacking mode of the diazapyrene radical cations, resulting in a redshift of their characteristic absorption peak from the visible region to the NIR region. Under 660 nm laser irradiation, the in situ-induced supramolecular radical assembly exhibits great photothermal conversion properties and achieves highly efficient antibacterial activity (up to 98%). In contrast, with the aerobic B. subtilis it is difficult to induce the formation of diazapyrene radical cations in situ and maintain good activity under light irradiation. In addition, DAPNP@CB[10] exhibits excellent biocompatibility and has great potential as an intelligent photothermal material for antibacterial applications.

Enantiopure Macrocycles Based on Tröger's Base and Diphenyl Maleimide Exhibiting Strong Chiral Emission and Host-Guest Properties

While a plenty of macrocyclic hosts have been developed in supramolecular chemistry, those that combine chiral luminescent properties and host-guest recognition abilities are still uncommon. Herein, two pairs of enantiomeric macrocycles were synthesized via Suzuki-Miyaura [2+2] cyclization reactions using Tröger's base and diphenyl maleimide as the building blocks. The diphenyl maleimide units impart these macrocycles with highly strong fluorescence, achieving quantum yields up to 100 % in apolar solvents. Furthermore, the chiral, V-shaped Tröger's base units provide the macrocycles with circularly polarized luminescence (|glum|=1.68×10-3) and well-define cavity for hosting electron-deficient or positively charged guests with Ka up to 1.7×106 M-1.

Luminescence Modulation in Boron-Cluster-Based Luminogens via Boron Isotope Effects

Recent advances in luminescent materials highlight the significant impact of hydrogen isotope effects on improving optoelectronic properties. However, the research on the influence of the boron isotope effects on photophysical properties remains underdeveloped. This study focused on exploring the boron isotope effects in boron-cluster-based luminogens. In doing so, we designed and synthesized carborane-based luminogens containing 98 % 10B and 95 % 11B, respectively, and observed distinct photophysical behaviors. Compared to the 10B-enriched luminogens, the 11B-enriched counterparts can significantly enhance luminescence efficiency, prolong emission lifetime, and reduce full-width at half-maximum. Additionally, increased thermal stability, redshifted B-H vibrations, and a fourfold enhanced electrochemiluminescence intensity have also been observed. On the other hand, the biological assessments of a 10B-enriched luminogen reveals low cytotoxicity, high boron uptake, and excellent fluorescence imaging capability, indicating the potential application in boron neutron capture therapy (BNCT). This work presents the first comprehensive exploration on the boron isotope effects in boron clusters, and provides valuable insights into the rational design of organic luminogens for advanced optoelectronic and biomedical applications.

A cucurbit[6]uril-based fluorescence supramolecular assembly for information encryption and visualization detection of nitro compounds and antibiotics

A novel CB[6]-based supramolecular assembly [K(ANS)(CB[6])2(DMF)2(H2O)0.5] (1) (CB[6] = cucurbit[6]uril, ANS- = 8-amino-1-naphthalene sulfonic acid ion) was successfully synthesized under solvothermal condition. Performance studies have shown that 1 exhibited excellent chemical stability and recycling performance. Meanwhile, 1 exhibited remarkable potential as a fluorescence sensor for the detection of 2,4,6-trinitrophenol (TNP), 4-nitrophenol (4-NP), and rifampicin (RFP) in both aqueous environments and practical samples. This sensing capability is achieved through fluorescence quenching, which offers fast response times and exceptional sensitivity, with detection limits of 0.19 μM for both TNP and 4-NP, and 0.21 μM for RFP. Even more remarkably, an anti-counterfeiting ink based on 1 and a portable test hydrogel were devised for encrypting information and visually detecting using a smartphone application. This work has the potential to expand the utilization of CB[6]-based materials in optical applications.

Tetramethyl Cucurbit[6]uril-Porphyrin Supramolecular Polymer Enhances Photosensitization

Porphyrins serve as photosensitizers (PS) in the realm of cancer photodynamic therapy (PDT). Upon excitation by laser light, porphyrins are capable of converting molecular oxygen into highly cytotoxic singlet oxygen (1O2). However, the rigid π-conjugated structure of porphyrins frequently results in the formation of aggregates in aqueous solutions, which leads to the self-quenching of the excited state. Cucurbit[n]urils exhibit the capacity to stably bind with porphyrins via host-guest interactions, effectively inhibiting their aggregation and potentially enhancing the therapeutic efficacy of PDT. In this study, water-soluble tetramethyl cucurbit[6]uril (TMeQ[6]) was selected as the host, while four propionic acid group-appended porphyrin cationic (TPPOR) was utilized as guests to construct a supramolecular photosensitizer (TPPOR-2TMeQ[6]) in a molar ratio of 2:1. Further experimental findings demonstrate that the presence of TMeQ[6] inhibits the aggregation of TPPOR through non-covalent interactions. This inhibition reduces the energy difference between the excited singlet and triplet states, thereby enhancing the conversion efficiency of 1O2. Moreover, TPPOR-2TMeQ[6] exhibits favorable biocompatibility and minimal dark toxicity against breast cancer cells (4T1). Upon intracellular excitation, the levels of reactive oxygen species (ROS) significantly increase, inducing oxidative stress in 4T1 cells and leading to apoptosis. Consequently, the findings of this study suggest that the enhanced photosensitization achieved through this supramolecular approach is likely to promote the anticancer therapeutic effects of PDT, thereby broadening the application prospects of porphyrins within PDT systems.

Tunable multicolor supramolecular assemblies based on phosphorescence cascade energy transfer for photocatalytic organic conversion and anti-counterfeiting

Making full use of the captured energy by phosphorescence light-harvesting systems (PLHSs) and the tunable photoluminescence in energy transfer process to realize the multiple applications is still the challenge of PLHSs research. In this study, we have successfully constructed a highly effective PLHS with tunable multicolor luminescence and efficient conversion of photosensitizer types, which can further be used in photocatalytic organic conversion, information anti-counterfeiting and storage. The supramolecular polymer of BDBP-CB[8], which is generated by cucurbit[8]uril (CB[8]) and 4-(4-bromophenyl)-pyridine derivative (BDBP), realizes a phosphorescence emission and a change in luminescence color. Notably, white light emission was achieved and the logic gate systems were constructed utilizing the application of adjustable luminescence color. More interestingly, PLHS can be constructed by employing BDBP-CB[8] as energy donors, Sulforhodamine 101 (SR101) and Cyanine5 (Cy5) as energy acceptors, which results in a remarkably tunable multicolor photoluminescence to achieve the information storage. Furthermore, we have also found that BDBP-CB[8] can serve as type II photosensitizer for the effective production of singlet oxygen (1O2) during the photooxidation process of styrene in aqueous environments, attaining a remarkable output rate reaching as high as 89 %. Particularly, compared with 1O2 produced by type II photosensitizer BDBP-CB[8], the construction of PLHS can effectively convert type II photosensitizer to type I photosensitizer and efficiently generate superoxide anion radical (O2•-), which can be used for photocatalytic cross-dehydrogenative coupling (CDC) reaction in the aqueous solution with a yield of 90 %. Thus, we have created a PLHS that not only achieves tunable multicolor emission for information anti-counterfeiting and storage, but also realizes the conversion of reactive oxygen species (ROS) for different types photocatalytic oxidation reactions.

Dual emitting aggregation-induced electrochemiluminescence from tetrastyrene derivative for chloramphenicol detection

Chloramphenicol (CAP) poses a threat to human health due to its toxicity and bioaccumulation, and it is very important to measure it accurately and sensitively. This work explored a host-guest recognition strategy to mediate dual aggregation-induced electrochemiluminescence (AIECL) of 1,1,2,2-tetrakis(4-(pyridin-4-yl) phenyl)-ethene (TPPE) for ratio detection of CAP, in which, cucurbit[8]uril (CB[8]) served as host to assemble guest TPPE. The resulting supramolecular complex CB[8]-TPPE exhibited excellent dual-AIECL-emission with signal strength approximately four times that of TPPE aggregates and black hole quencher-1 (BHQ1) could efficiently quench dual-AIECL signal. CB[8]-TPPE coupled dual-function quencher BHQ1 and high-efficiency DNA reactor to achieve ultra-sensitive detection of CAP, exhibiting a linearity range of 10 fmol·L-1-100 nmol·L-1 and limit of detection of 1.81 fmol·L-1. CB[8]-TPPE provides a novel way to improve the dual-emission of TPE derivatives and sets up a promising platform for CAP detection, demonstrating a good practical application potential.

Expanding the Color Range of Photoresponsive Multicolor Luminescent System Through Host-Guest Interaction

Photoresponsive multicolor luminescent systems offer interesting functions, which have led to applications in anticounterfeiting and biological imaging. However, expanding the color range of these materials remains a challenging task. Herein, a carbazole-modified dithienylethene derivative (DTE-CZ) that exhibits modulated fluorescence color changes through the photocyclization reaction and photolysis reaction is synthesized. DTE-CZ emits orange fluorescence, and it can release a fluorophore which emits blue fluorescence by the photolysis reaction, resulting in the color change. Upon complexation of DTE-CZ with cucurbit[10]uril (CB[10]), the fluorescence wavelength will have a blue shift and the photolysis reaction will be inhibited. Benefiting from the influence of CB[10] and the photolysis reaction of free guests, the color range of the photoresponsive system which is composed of free guests and host-guest complexes is further extended. White light emission along with a color shift from yellow-green to blue was achieved by adjusting the ratio of free guests to host-guest complexes. Finally, the photoresponsive multicolor systems are utilized to construct a photostimulated PVA film and an information encryption system. This work provides an alternative strategy for the preparing of photoresponsive multicolor luminescent system and modulation of its color range.

Supramolecular Exchange Reaction in the Cavity of Naphthalene Diimides Extended-Pillar[6]arene

A new naphthalene diimides extended-pillar[6]arene 1 with a large cavity and rich host-guest complexation properties was synthesized in high yield. It can not only form 1 : 2 complexes with large size polycyclic aromatic hydrocarbons but also form 1 : 1 : 1 ternary complex with perylene and 2,7-diazapyrenium. Moreover, the supramolecular exchange reaction from a 1 : 2 host-guest complex 1 ⋅ (G3)2 formed by 1 and perylene to a 1 : 1 : 1 ternary complex 1 ⋅ G3 ⋅ G5 formed by 1 with perylene and 2,7-diazapyrenium salt was also investigated by 1H NMR experiments as well as theoretically calculations.

Achieving Tunable Monomeric TADF and Aggregated RTP via Molecular Stacking

Organic emitters with both thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) have attracted widespread interest for their intriguing luminescent properties. Herein, a series of triphenylamine-substituted isoquinoline derivatives possessing monomeric TADF and aggregated RTP properties are reported. As the molecules exhibited various forms of π-π and charge transfer (CT) stacking with different intensities, inter/intramolecular CT can be meticulously modulated to achieve tunable TADF-RTP. Aggregated phosphorescence originates from intermolecular CT initiated by CT dimers, whereas monomeric TADF is facilitated by intramolecular CT enhanced by π-π dimers. Leveraging the properties of these molecules, luminescent materials with tunable TADF-RTP properties in multistates are obtained by molecular substitution position alignment, dealing with different solvents, grinding, adjusting concentration, changing polymer matrix, photoactivation, and heat treatment. This work is critical for a deeper understanding of construction and regulation of the TADF-RTP dual-channel emission, enabling the development of advanced optoelectronic devices with tailored emission properties.

A dual-state emission luminogen for lipid droplet imaging and photodynamic therapy

Organic luminogens with dual-state emission (DSE) have garnered widespread attention due to their versatility in the forms of both dilute solutions and solids. Despite the growing interest, most research on DSE focuses primarily on molecule design and photophysical investigation, with limited exploration of their practical applications. In this study, we introduce a novel fluorescent molecule, PCT, featuring a distinct D-π(A)-D' electronic structure. PCT exhibited efficient DSE properties, with high quantum yields in both dilute solutions (ΦTHF = 52.3 %) and solid-state (Φsolid = 74.6 %). Taking advantage of PCT's lipophilicity, we demonstrated its potential for targeted lipid droplet (LD) imaging in living cells and its utility in monitoring LD depletion during cellular starvation. To further enhance its applicability in photodynamic therapy (PDT), PCT was encapsulated within the amphiphilic triblock copolymer Pluronic F127, forming PCT@F127 nanoparticles with improved colloidal stability. These nanoparticles efficiently generated singlet oxygen (1O2) under white light irradiation, achieving a 1O2 quantum yield of 57.2 %. In vitro studies on MCF-7 cells revealed significant 1O2 generation and potent phototoxicity, leading to marked cell apoptosis and necrosis. These results underscore PCT's multifunctionality as a DSEgen, with promising applications in both bioimaging and PDT.

Transient cucurbit[7]uril-mediated host-guest complexes for time-dependent fluorescence and information-self-erasing hydrogel

A non-equilibrium cucurbit[7]uril-mediated supramolecular host-guest system is fabricated by using urea/urease to control aqueous solution pH on time dimension, showing transient assembly behavior and time-dependent fluorescence. The dynamic assembly can be also achieved in hydrogel network, resulting in a time-dependent fluorescent hydrogel for information encryption.

Guest-Mediated Modulation of Photophysical Pathways in a Coronene Bisimide Cyclophane

The properties and functions of chromophores utilized by nature are strongly affected by the environment formed by the protein structure in the cells surrounding them. This concept is transferred here to host-guest complexes with the encapsulated guests acting as an environmental stimulus. A new cyclophane host based on coronene bisimide is presented that can encapsulate a wide variety of planar guest molecules with binding constants up to (4.29 ± 0.32) × 1010 M-1 in chloroform. Depending on the properties of the chosen guest, the excited state deactivation of the coronene bisimide chromophore can be tuned by the formation of host-guest complexes toward fluorescence, exciplex formation, charge separation, room-temperature phosphorescence (RTP), or thermally activated delayed fluorescence (TADF). The photophysical processes were investigated by UV/vis absorption, emission, and femto- and nanosecond transient absorption spectroscopy. To enhance the TADF, two different strategies were used by employing suitable guests: the reduction of the singlet-triplet gap by exciplex formation and the external heavy atom effect. Altogether, by using supramolecular host-guest complexation, a versatile multimodal chromophore system is achieved with the coronene bisimide cyclophane.

Supramolecular light-harvesting systems utilizing tetraphenylethylene chromophores as antennas

Efficient utilization of light energy is crucial for various technological applications ranging from solar energy conversion to optoelectronic devices. Supramolecular light-harvesting systems (LHS) have emerged as promising platforms for enhancing light absorption and energy transfer process. In this Feature Article, we highlight the utilization of tetraphenylethylene (TPE) chromophores as antennas in supramolecular assemblies for light harvesting applications. TPE, as an archetypal aggregation-induced emission (AIE) chromophore, offers unique advantages such as high photostability and efficient light-harvesting capabilities upon self-assembly. We discuss the design principles and synthetic strategies employed to construct supramolecular assemblies incorporating TPE chromophores, elucidating their roles as efficient light-harvesting antennas. Furthermore, we delve into the mechanisms governing energy transfer processes within these assemblies, such as Förster resonance energy transfer (FRET). The potential applications of these TPE-based supramolecular systems in various fields, including photocatalysis, reactive oxygen species generation, optoelectronic devices and sensing, are explored. Finally, we provide insights into future directions and challenges in the development of next-generation supramolecular LHSs utilizing TPE chromophores.

Prediction of binding affinity and enthalpy of CB7 with alkaloids by attach-pull-release molecular dynamics simulations study

Host-guest complex has attracted much attention because of their fantastic capability. Accurate prediction of their binding affinity and enthalpy is essential to the rational design of guest molecules. The attach-pull-release (APR) method proposed by Henriksen et al. (J. Chem. Theory Comput., 2015, 11:4377.) shows good prediction capability of binding affinity especially for host-guest system. In order to further evaluate the performance of APR method in practice, we have conducted the calculations on the macrocycle cucurbit [7]urils (CB7) encapsulated with four structurally similar alkaloids (berberine, coptisine, epiberberine and palmatine) with two force fields (GAFF and GAFF2) and three water models (TIP3P, SPC/E and OPC). Compared to the experimental data, the calculation by the combination of GAFF2 and SPC/E force field presents the best performance, of which the Pearson correlation coefficients (R2) is 0.95, and the root-mean-square-deviation is 3.04 kcal/mol. While the predictions from GAFF force field all overestimated the binding affinity, suggesting a systematic error may be involved. Comparison of calculation also indicates that the accuracy of prediction was susceptible to the combination of force field. Therefore, it would be necessary to repeat the simulation with different combination of force fields in practice.

Calix[2]azolium[2]benzimidazolone hosts for selective binding of neutral substrates in water

The separation and purification of chemical raw materials, particularly neutral compounds with similar physical and chemical properties, represents an ongoing challenge. In this study, we introduce a class of water-soluble macrocycle compound, calix[2]azolium[2]benzimidazolone (H), comprising two azolium and two benzimidazolone subunits. The heterocycle subunits form a hydrophobic binding pocket that enables H1 to encapsulate a series of neutral guests in water with 1:1 or 2:1 stoichiometry, including aldehydes, ketones, and nitrile compounds. The host-guest complexation in the solid state was further confirmed through X-ray crystallography. Remarkably, H1 was shown to be a nonporous adaptive crystal material to separate valeraldehyde from the mixture of valeraldehyde/2-methylbutanal/pentanol with high selectivity and recyclability in the solid states. This work not only demonstrates that azolium-based macrocycles are promising candidates for the encapsulation of organic molecules but also shows the potential application in separation science.

Self-Inclusion Complexation of Electron-Accepting Guest into Electron-Donating Cyclic Host by Photoexcitation

Self-inclusion complexes consisting of host-guest conjugates are one of the unique supramolecular structures because they form in-state and out-state depending on the external stimuli. Despite many reports of the stimuli-responsive self-inclusion complex formation, study of the structural relaxation from out-state to in-state by photoexcitation has been unexplored. Herein, we report that an electron-donating host and an electron-accepting guest conjugate exhibits the structural relaxation from out-state to in-state by photoexcitation. Formation of the in-state in the excited state resulted in exciplex emission along with the locally excited emission from the out-state. Moreover, this structural relaxation by photoexcitation was suppressed not only by temperature, but also by the presence of guest molecules, resulting in changes in the ratio of the dual emission intensities.

Dual catalytic activity of a cucurbit[7]uril-functionalized metal alloy nanocomposite for sustained hydrogen generation: hydrolysis of ammonia borane and electrocatalysts for the hydrogen evolution reaction

H2 is one of the most attractive fuel alternatives to the existing fossil fuels that cause detrimental environmental issues. Thus, there has been an upsurge in the research on the production of green hydrogen. In this view, cucurbit[7]uril (CB7)-functionalized Co:Ni alloy nanocomposites with different compositions, reported here for the first time, were synthesized to synergise the catalytic activities of a nanoalloy and CB7 and screened for hydrogen generation via hydrolysis of ammonia borane (AB). The (Co85:Ni15)50:(CB7)50 nanocomposite exhibited enhanced catalytic performance for AB hydrolysis even at room temperature as compared to the nanoalloy without CB7. Efficient release of ammonia-free green H2 is ensured by the retention of NH3 by the surface functionalized CB7 macrocycles. For sustained release, a novel and cost-effective procedure was used to regenerate AB from the by-product, and the H2 release activity was verified to be on par with commercial AB. The used nanocomposite magnetically separated from the by-product solution was shown to be an efficient electrochemical catalyst for the hydrogen evolution reaction (HER). The cucurbit[7]uril-functionalized Co:Ni nanocomposite demonstrates remarkable dual catalytic performance to generate clean hydrogen from both the hydrolysis of AB at room temperature and the electrochemical HER, thus opening new avenues in supramolecular chemistry for developing noble metal-free catalysts with high activity and long-term stability.

Strategies for Constructing Macrocyclic Arene-Based Color-Tunable Supramolecular Luminescent Materials

Over the past decades, supramolecular luminescent materials (SLMs) have attracted considerable attention due to their dynamic noncovalent interactions, versatile functions, and intriguing applications in many research fields. From construction to application, great efforts and progress have been made in color-tunable SLMs in recent years. In order to realize multicolor luminescence, various design strategies have been proposed. Macrocyclic chemistry, one of the brightest jewels in the field of supramolecular chemistry, has played a crucial role in the construction of stimuli-responsive and emission-tunable SLMs. Moreover, the flexible and tunable conformation and multiple noncovalent complexation sites of the macrocyclic arenes (MAs) afford a new opportunity to create such dynamic smart luminescent materials. Inspired by our reported work on the color-tunable supramolecular crystalline assemblies modulated by the conformation of naphth[4]arene, this Concept provides a summary of the latest developments in the construction of color-tunable MA-based SLMs, accompanied by the various construction strategies. The aim is to provide researchers with a new perspective to construct color-tunable SLMs with fascinating functions.

Achieving Efficient Dark Blue Room-Temperature Phosphorescence with Ultra-Wide Range Tunable-Lifetime

Tunable-lifetime room-temperature phosphorescence (RTP) materials have been widely studied due to their broad applications. However, only few reports have achieved wide-range lifetime modulation. In this work, ultra-wide range tunable-lifetime efficient dark blue RTP materials were realized by doping methyl benzoate derivatives into polyvinyl alcohol (PVA) matrix. The phosphorescence lifetimes of the doped films can be increased from 32.8 ms to 1925.8 ms. Such wide range of phosphorescence lifetime modulation is extremely rare in current reports. Moreover, the phosphorescence emission of the methyl 4-hydroxybenzoate-doped film is located in the dark blue region and the phosphorescence quantum yield reaches as high as 15.4 %, which broadens their applications in organic optoelectronic information. Further studies demonstrated that the reason for the tunable lifetime was that the magnitude of the electron-donating ability of the substituent group modulates the HOMO-LUMO and singlet-triplet energy gap of methyl benzoate derivatives, as well as the ability to non-covalent interactions with PVA. Moreover, the potential applications of luminescent displays and optical anti-counterfeiting of these high-performance dark blue RTP materials have been conducted.

Narrowband Organic/Inorganic Hybrid Afterglow Materials

Narrowband afterglow materials display interesting functions in high-quality anti-counterfeiting and multiplexed bioimaging. However, there is still a limited exploration of these afterglow materials, especially for those with a full width at half maxima (FWHM) around 30 nm. Here, we report the fabrication of narrowband organic/inorganic hybrid afterglow materials via energy transfer technology. Coronene (Cor) with a long phosphorescence feature and broad phosphorescence band is selected as the donor for energy transfer, and inorganic quantum dots (QDs) of CdSe/ZnS with a narrowband emission are used as acceptors. Upon doping into the organic matrix, the resultant three-component materials exhibit a narrowband afterglow with an afterglow lifetime of approximately 3.4 s and an FWHM of 31 nm. The afterglow wavelength of the afterglow materials can be controlled by the QDs. This work based on organic/inorganic hybrids provides a facile approach for developing multicolor and narrowband afterglow materials, as well as opens a new way for expanding the features of organic afterglow for multifunctional applications. It is expected to rely on narrowband afterglow emitters to solve the "spectrum congestion" problem of high-density information storage in optical anti-counterfeiting and information encryption.

Single-Molecule Stoichiometry of Supramolecular Complexes

The use of single-molecule microscopy is introduced as a method to quantify the photophysical properties of supramolecular complexes rapidly at ultra low concentrations (<1 nM), previously inaccessible. Using a model supramolecular system based on the host-guest complexation of cucurbit[n]uril (CB[n]) macrocycles together with a fluorescent guest (Ant910Me), we probe fluorescent CB[n] host-guest complexes in the single molecule regime. We show quantification and differentiation of host-guest photophysics and stoichiometries, both in aqueous media and noninvasively in hydrogel, by thresholding detected photons. This methodology has wide reaching implications in aiding the design of next-generation materials with programmed and controlled properties.

Cucurbit[8]uril-based supramolecular theranostics

Different from most of the conventional platforms with dissatisfactory theranostic capabilities, supramolecular nanotheranostic systems have unparalleled advantages via the artful combination of supramolecular chemistry and nanotechnology. Benefiting from the tunable stimuli-responsiveness and compatible hierarchical organization, host-guest interactions have developed into the most popular mainstay for constructing supramolecular nanoplatforms. Characterized by the strong and diverse complexation property, cucurbit[8]uril (CB[8]) shows great potential as important building blocks for supramolecular theranostic systems. In this review, we summarize the recent progress of CB[8]-based supramolecular theranostics regarding the design, manufacture and theranostic mechanism. Meanwhile, the current limitations and corresponding reasonable solutions as well as the potential future development are also discussed.

Enhancing Purely Organic Room Temperature Phosphorescence via Supramolecular Self-Assembly

Long-lived and highly efficient room temperature phosphorescence (RTP) materials are in high demand for practical applications in lighting and display, security signboards, and anti-counterfeiting. Achieving RTP in aqueous solutions, near-infrared (NIR) phosphorescence emission, and NIR-excited RTP are crucial for applications in bio-imaging, but these goals pose significant challenges. Supramolecular self-assembly provides an effective strategy to address the above problems. This review focuses on the recent advances in the enhancement of RTP via supramolecular self-assembly, covering four key aspects: small molecular self-assembly, cocrystals, the self-assembly of macrocyclic hosts and guests, and multi-stage supramolecular self-assembly. This review not only highlights progress in these areas but also underscores the prominent challenges associated with developing supramolecular RTP materials. The resulting strategies for the development of high-performance supramolecular RTP materials are discussed, aiming to satisfy the practical applications of RTP materials in biomedical science.

Tunable Fluorescence, Morphology, and Antibacterial Behaviors of Conjugated Oligomers via Host-Guest Supramolecular Self-Assembly

Host-guest supramolecular self-assembly has become one facile but efficient way to regulate the optical properties of conjugated oligomers and construct promising photofunctional materials. Herein, we design two linear conjugated oligomers terminated with two or four pyridinium moieties, which show different 1:1 'head-to-tail' binding patterns with cucurbit[8]uril (CB[8]) to form host-guest supramolecules. After being encapsulated in the hydrophobic cavity of the CB[8] host, the fluorescence emission of the conjugated oligomers undergoes significant changes, resulting in tunable fluorescence color with enhanced quantum yields. Triggered by the aggregation of supramolecules, the regular or rigid binding modes lead to the formation of cuboids and spheroids in nanoscale, respectively. Due to the macrocyclic-confinement effect, the light-driven reactive oxygen species (ROS) production of the host-guest complex is increased significantly, thereby improving the photodynamic antibacterial performance toward Staphylococcus aureus (S. aureus).

A Cucurbit[8]uril-Based Supramolecular Framework Material for Reversible Iodine Capture in the Vapor Phase and Solution

The safe and efficient management of hazardous radioactive iodine is significant for nuclear waste reprocessing and environmental industries. A novel supramolecular framework compound based on cucurbit[8]uril (Q[8]) and 4-aminopyridine (4-AP) is reported in this paper. In the single crystal structure of Q[8]-(4-AP), two 4-AP molecules interact with the outer surface of Q[8] and the two other 4-AP molecules are encapsulated into the Q[8] cavity to form the self-assembly Q[8]-(4-AP). Iodine adsorption experiments show that the as-prepared Q[8]-(4-AP) not only has a high adsorption capacity (1.74 g· g-1) for iodine vapor but also can remove the iodine in the organic solvent and the aqueous solution with the removal efficiencies of 95% and 91%, respectively. The presence of a large number of hydrogen bonds between the iodine molecule and the absorbent, as seen in the single crystal structure of iodine-loaded Q[8]-(4-AP) (I2@Q[8]-(4-AP)), is thought to be responsible for the exceptional iodine adsorption capacity of the material. In addition, the adsorption-desorption tests reveal that the self-assembly material has no significant loss of iodine capture capacity after five cycles, indicating that it has sufficient reusability.

Evaluation of the complexation behaviour among functionalized diphenyl viologens and cucurbit[7] and [8]urils

The complexation behaviour of Diphenyl viologens (DPVs) with Cucurbit[n]urils (CB[n]) was evaluated in detail and the results were reported. In this work, we present the synthesis of various DPVs functionalised with electron withdrawing and electron donating groups (EWGs & EDGs) and investigate their complexation behaviour with CB[7] and CB [8]. Carboxylic acid functionalized DPV's (DPV-COOH) complexation with CB[8] gives additional insights, i.e., indicates hydrogen bonding plays an effective role in the complexation. The formation of a 2:2 quaternary complex of DPV-COOH/CB[8] under neutral pH conditions was supported by various analytical techniques. The complexation of DPVs with CB[7] specifies that irrespective of the functional group attached, they all form a 1:2 ternary complex, but the findings elaborate that the pattern followed in the complexation depends on the EW or EDG attached to the DPVs. The competition experiments conducted between functionalized DPVs and CB[7], CB[8] shows that they have more affinity towards CB[8] than CB[7] because of the better macrocyclic confinement effect of CB[8], as confirmed using UV-Vis spectroscopy. The binding affinity among EWG and EDG functionalised DPVs with CB[8] concludes EDG functionalised DPVs show better affinity towards CB[8], because they can form a charge transfer complex inside the CB[8] cavity. Exploring these host-guest interactions in more complex biological or environmental settings and studying their impact on the functionality of DPVs could be an exciting avenue for future research.

A molecular container providing supramolecular protection against acetylcholine hydrolysis

Alzheimer's disease (AD) is characterized by cognitive decline, often attributed to the deficiency of acetylcholine, which can undergo hydrolysis by acetylcholinesterase (AChE) within the biological milieu. Here, we report a supramolecular strategy that takes advantage of confinement effects to inhibit such a hydrolysis process, shedding some light on AD therapy. A water-soluble and bowl-shaped molecule, hexacarboxylated tribenzotriquinacene (TBTQ-C6), was employed to shield acetylcholine (G1) from enzymatic degradation through host-guest binding interactions. Our study revealed highly efficient host-guest interactions with a binding ratio of 1 : 3, resulting in a significant reduction in acetylcholine hydrolysis from 91.1% to 7.4% in the presence of AChE under otherwise identical conditions. Furthermore, TBTQ-C6 showed potential for attenuating the degradation of butyrylcholine (G2) by butyrylcholinesterase (BChE). The broader implications of this study extend to the potential use of molecular containers in various biochemical and pharmacological applications, opening new avenues for research in the field of neurodegenerative diseases.

Overcoming barriers with non-covalent interactions: supramolecular recognition of adamantyl cucurbit[n]uril assemblies for medical applications

Adamantane, a staple in medicinal chemistry, recently became a cornerstone of a supramolecular host-guest drug delivery system, ADA/CB[n]. Owing to a good fit between the adamantane cage and the host cavity of the cucurbit[n]uril macrocycle, formed strong inclusion complexes find applications in drug delivery and controlled drug release. Note that the cucurbit[n]uril host is not solely a delivery vehicle of the ADA/CB[n] system but rather influences the bioactivity and bioavailability of drug molecules and can tune drug properties. Namely, as host-guest interactions are capable of changing the intrinsic properties of the guest molecule, inclusion complexes can become more soluble, bioavailable and more resistant to metabolic conditions compared to individual non-complexed molecules. Such synergistic effects have implications for practical bioapplicability of this complex system and provide a new viewpoint to therapy, beyond the traditional single drug molecule approach. By achieving a balance between guest encapsulation and release, the ADA/CB[n] system has also found use beyond just drug delivery, in fields like bioanalytics, sensing assays, bioimaging, etc. Thus, chemosensing in physiological conditions, indicator displacement assays, in vivo diagnostics and hybrid nanostructures are just some recent examples of the ADA/CB[n] applicability, be it for displacements purposes or as cargo vehicles.

Imaging GPCR Dimerization in Living Cells with Cucurbit[7]uril and Hemicyanine as a "Turn-On" Fluorescence Probe

Although multiple forms of dimers have been described for GPCR, their dynamics and function are still controversially discussed field. Fluorescence microscopy allows GPCR to be imaged within their native context; however, a key challenge is to site-specifically incorporate reporter moieties that can produce high-quality signals upon formation of GPCR dimers. To this end, we propose a supramolecular sensor approach to detect agonist-induced dimer formation of μ-opioid receptors (μORs) at the surface of intact cells. With the macrocyclic host cucurbit[7]uril and its guest hemicyanine dye tethered to aptamer strands directed against the histidine residues, the sensing module is assembled by host-guest complexation once the histidine-tagged μORs dimerize and bring the discrete supramolecular units into close proximity. With the enhanced sensitivity attributed by the "turn-on" fluorescence emission and high specificity afforded by the intermolecular recognition, in situ visualization of dynamic GPCR dimerization was realized with high precision, thereby validating the supramolecular sensing entity as a sophisticated and versatile strategy to investigate GPCR dimers, which represent an obvious therapeutic target.

Cucurbit[8]uril-Based Supramolecular Probe for the Detection of 3-Nitrotyrosine in Human Serum and Plasma

The biomarker 3-nitrotyrosine (3-NT) is widely recognized as an indicator of renal oxidative stress injury, making its detection crucial for the early identification of renal insufficiency. This study presents the design and synthesis of a tetraphenylstyrene imidazole derivative (TIPE-MI), which is utilized to create a supramolecular probe in conjunction with cucurbit[8]uril (Q[8]) through host-guest interactions. The resulting supramolecular self-assembly exhibits excellent optical properties and has been employed for the specific detection of 3-NT through fluorescence quenching. The introduction of 3-NT resulted in a decreased fluorescence intensity of the yellow fluorescent probe, which gradually transitioned from bright yellow to light yellow and then became colorless as the 3-NT concentration was increased. A portable detection platform was devised to augment the efficiency of detection. In order to facilitate biological applications, we have substantiated the probe's exceptional precision in detecting 3-NT in biological samples, encompassing human serum and plasma. The probe also exhibited negligible cytotoxicity. The accumulation of the probe in renal cells elicited a fluorescence signal, thereby indicating the prospective viability of this system for visual detection with renal cytocompatibility.

Cucurbituril-based supramolecular host-guest complexes: single-crystal structures and dual-state fluorescence enhancement

Two supramolecular complexes were prepared using cucurbiturils [CBs] as mediators and a four-armed p-xylene derivative (M1) as a guest molecule. The single crystals of these two complexes were obtained and successfully analyzed by single-crystal X-ray diffraction (SCXRD). An unexpected and intriguing 1 : 2 self-assembly arrangement between M1 and CB[8] was notably uncovered, marking its first observation. These host-guest complexes exhibit distinctive photophysical properties, especially emission behaviors. Invaluable insights can be derived from these single-crystal structures. The precious single-crystal structures provide both precise structural information regarding the supramolecular complexes and a deeper understanding of the intricate mechanisms governing their photophysical properties.