A Twisted Cucurbit[14]Uril-Based Fluorescent Supramolecular Polymer Mediated by Metal Ion

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.

A Highly Efficient Supramolecular Polymer-Based Singlet Oxygen Generator for Photocatalytic Minisci Alkylation

Supramolecular polymers, with their specific functional units and structures, can effectively enhance the absorption and utilization of light energy, thereby facilitating more efficient photocatalytic organic reactions. In the present work, we constructed a supramolecular polymer consisting of benzothiazole derivatives (BTBP) and cucurbit[8]uril (CB[8]). The BTBP monomer, known for its unique chemical structure and properties, has been found to exhibit a remarkable capability in generating singlet oxygen (1O2). As a result of the constraining impact of the macrocyclic molecule, the inclusion of CB[8] resulted in an effective enhancement in the ability to generate 1O2 while forming supramolecular polymer BTBP-CB[8]. When evaluating the quantum yield of 1O2 using Rose Bengal (RB) as a reference photosensitizer (75% in water), BTBP-CB[8] demonstrated an enhanced 1O2 quantum yield compared to BTBP, with an impressive yield of 152.4%, demonstrating that the formation of supramolecular polymer contributes to its ability to generate 1O2. Subsequently, BTBP-CB[8], a highly efficient 1O2 generator, was employed for the photocatalytic Minisci alkylation reaction, resulting in an impressive reaction yield of up to 89%. The supramolecular polymer strategies employed in the construction of photocatalytic systems have exhibited remarkable efficacy in the production of 1O2, underscoring their immense prospects in photocatalysis.

Selective detection of paraquat by a cucurbit[7]uril-based fluorescent probe

A simple fluorescent "on-off" system that can be utilized for the selective identification and determination of paraquat (PQ) is presented herein. 1H NMR spectroscopic data indicated that in aqueous solution the alkaloid palmatine can be partially encapsulated within the cucurbit[7]uril (Q[7]) cavity, whereby a stable 1 : 1 host-guest inclusion complex is formed. Other characterization techniques including mass spectrometry, UV-Vis and fluorescence spectroscopy also provided further evidence, and the host-guest inclusion complex was found to exhibit reasonable fluorescence intensity. It is noteworthy that the addition of PQ resulted in quenching the fluorescence of the host-guest inclusion complex, whereas the presence of 12 other pesticides did not significantly affect the fluorescence intensity. Given the linear relationship between the intensity of the fluorescence and the PQ concentration, the PQ concentration in aqueous solution was easily detected. Thus, a new method for identifying and determining the fluorescence quenching of PQ has been developed in this work.

Double-cavity cucurbiturils: synthesis, structures, properties, and applications

Double-cavity Q[n]s are relatively new members of the Q[n] family and have garnered significant interest due to their distinctive structures and novel properties. While they incorporate n glycoluril units, akin to their single-cavity counterparts, their geometry can best be described as resembling a figure-of-eight or a handcuff, distinguishing them from single-cavity Q[n]s. Despite retaining the core molecular recognition traits of single-cavity Q[n]s, these double-cavity variants introduce fascinating new attributes rooted in their distinct configurations. This overview delves into the synthesis, structural attributes, properties, and intriguing applications of double-cavity Q[n]s. Some of the applications explored include their role in supramolecular polymers, molecular machinery, supra-amphiphiles, sensors, artificial light-harvesting systems, and adsorptive separation materials. Upon concluding this review, we discuss potential challenges and avenues for future development and offer valuable insights for other scholars working in this area with the aim of stimulating further exploration and interest.

Construction of an Artificial Light-Harvesting System with Photocatalytic Activity Based on Nor-seco-cucurbit[10]uril in Aqueous Solution

A supramolecular assembly was constructed based on the tetraphenylethylene derivatives (TPEs) and nor-seco-cucurbit[10]uril (ns-Q[10]). Upon introduction of the dye Rhodamine B (RB) into the TPEs@ns-Q[10] assembly, an energy transfer process can occur from the TPEs@ns-Q[10] assembly to RB. Moreover, after the addition of Nile Red (NiR), a two-step sequential energy transfer process from the TPEs@ns-Q[10] assembly to RB and then to NiR can occur. Additionally, the dye Eosin Y (ESY) was introduced into the TPEs@ns-Q[10] assembly and an energy transfer process can take place from the TPEs@ns-Q[10] assembly to ESY. To utilize the harvested energy from the TPEs@ns-Q[10]-RB-NiR and TPEs@ns-Q[10]-ESY system, we applied the TPEs@ns-Q[10] assembly-based light-harvesting systems (LHSs) as a catalyst for the advancement of the photocatalytic dehalogenation reaction in aqueous solution. When promoted with 0.5 mol % catalyst, the reaction yield reached 78 and 68%, demonstrating the promising potential of TPEs@ns-Q[10] assembly-based LHSs in the promotion of the photocatalytic dehalogenation reaction.

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.

Supramolecular Crystal Networks Constructed from Cucurbit[8]uril with Two Naphthyl Groups

Naphthyl groups are widely used as building blocks for the self-assembly of supramolecular crystal networks. Host-guest complexation of cucurbit[8]uril (Q[8]) with two guests NapA and Nap1 in both aqueous solution and solid state has been fully investigated. Experimental data indicated that double guests resided within the cavity of Q[8], generating highly stable homoternary complexes NapA₂@Q[8] and Nap1₂@Q[8]. Meanwhile, the strong hydrogen-bonding and π···π interaction play critical roles in the formation of 1D supramolecular chain, as well as 2D and 3D networks in solid state.

Supramolecular Room Temperature Phosphorescent Materials Based on Cucurbit[8]uril for Dual Detection of Dodine

In recent years, host-guest interactions of macrocycles have attracted much attention as an emerging method for enhancing the intersystem crossing of pure organic room-temperature phosphorescence. In this work, we utilize cucurbit[8]uril (Q[8]) to specifically recognize synthetic bromophenyl pyridine derivatives (BPCOOH) to construct a highly stable charge-transfer dimer, where the bromophenyl pyridine moiety of BPCOOH is encapsulated by Q[8] in a 1:2 host/guest ratio. The assemblies exhibit specific recognition and detection properties for dodine on both fluorescence and phosphorescence spectra. Subsequently, the solid films were prepared by introducing carboxymethylcellulose sodium into the assemblies, which greatly enhanced its RTP performance by increasing the noncovalent bonding interactions, enabling the visualization of high-strength RTP and quantitative testing of the solid state. Finally, this material was used for the application of portable indicator papers to achieve rapid and visualized detection of dodine in daily life, which provides more possibilities for the potential applications of cucurbit[n]uril-based room-temperature phosphorescence material.

Cucurbit[10]uril-Based Orthogonal Supramolecular Polymers with Host-Guest and Coordination Interactions and Its Applications in Anion Classification

A novel orthogonal supramolecular polymer (Q[10]-TPDPB-Lu³⁺) in a host-guest ratio of 2:1 was successfully constructed utilizing the specificity and excellent cavity matching of Q[10] with the tripyridine derivatives (TPDPB). Significantly, non-covalent interactions between Q[10]'s hydrophobic cavities and Lu³⁺ were used to induce charge transfer of TPDPB to TPDPB and TPDPB to Lu³⁺, resulting in the construction of structurally interesting orthogonal assemblies with excellent fluorescence properties. Finally, the Q[10]-TPDPB-Lu³⁺ assemblies were shown to have good recognition and classification of strong and weak acid anions as well as iodide anions, and the classification was accompanied by a clear fluorescence emission change allowing visual observation.

Cucurbit [8] uril-based supramolecular fluorescent biomaterials for cytotoxicity and imaging studies of kidney cells

An accurate diagnosis of acute kidney injury (AKI) at the early stage is critical to not only allow preventative treatments in time but also forecast probable medication toxicity for preventing AKI from starting and progressing to severe kidney damage and death. Therefore, supramolecular fluorescent biomaterials based on Q [8] and PEG-APTS have been prepared herein. This study has found that the unique properties of outer surface methine and the positive density of Q [8] can form a stable assembly with PEG-APTS, and has provided the possibility for the faster crossing of the glomerular filtration barrier to enter into the resident cells of the kidney. In addition to the excellent fluorescence properties, the as-synthesized biomaterial Q [8]@PEG-APTS has possessed significantly low biological toxicity. Most importantly, the accumulation of Q [8]@PEG-APTS in large amounts in cytoplasm and nucleus of HK2 and HMCs cells, respectively, within 24 h enabled distinguishing kidney cells when diagnosing and providing some foundation for early AKI.

Supramolecular Polymeric Material Based on Twisted Cucurbit[14]uril: Sensitive Detection and Removal of Potential Cyanide from Water

Potassium ferricyanide in an aqueous solution is easily decomposed into highly toxic substances (potassium cyanide and hydrogen cyanide) by light or alkaline action, which poses a major hazard to environmental and human health. Here, a reticulated aggregation-induced emission (AIE) supramolecular polymer material (TPAP-Mb@tQ[14]) was prepared by the supramolecular self-assembly of twisted cucurbit[14]uril (tQ[14]) and a triphenylamine derivative (TPAP-Mb). TPAP-Mb@tQ[14] not only recognizes Fe(CN)₆^3- with sensitive specificity with a limit of detection (LOD) of 1.64 × 10^-7 M but can also effectively remove and adsorb Fe(CN)₆^3- from an aqueous solution with a removal rate as high as 97.38%. Meanwhile, an important component of the supramolecular polymer material (tQ[14]) can be reused. Thus, the tQ[14]-based supramolecular assembly has the potential to be used for applications addressing toxic anionic contaminants present in aqueous environments.

Highly Efficient Artificial Light-Harvesting Systems Constructed in an Aqueous Solution Based on Twisted Cucurbit[14]Uril

Relying on the supramolecular self-assembly of twisted cucurbit[14]urils (tQ[14]), anthracene derivatives (ADPy), Nile red (NiR), and rhodamine B (RB), highly efficient light-harvesting systems have been successfully designed in an aqueous medium. The addition of tQ[14] causes ADPy to aggregate through supramolecular self-assembly to form a supramolecular polymer (ADPy@tQ[14]) with excellent aggregation-induced fluorescence and an interesting spherical external morphology, making it a remarkable energy donor. Consequently, efficient energy-transfer processes have occurred between ADPy@tQ[14] assembly and NiR and RB, which both serve as effective energy acceptors while being loaded onto ADPy@tQ[14]. In the case of NiR, the energy-transfer efficiency is up to 72.45%, and the antenna effect is near 55.4 at a donor/acceptor ratio of 100:1, making it close to the light-harvesting systems in nature. As a result, effective water-soluble artificial light-harvesting systems are showing enormous prospective as versatile platforms for simulating photosynthesis.