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Macrocycle engineering is a key topic in supramolecular chemistry. When synthesizing a ring, one can obtain either complex mixtures of macrocycles of different sizes or a single ring if a template is utilized. Here, we unite these approaches along with post‐synthetic modifications to transform a single tether into multiple rings—up to five per tether. The macrocycles contain two bridged phenylpyridine ligands that are connected through a Pt atom, which defines the rings' shape, size, and host activity. All rings undergo redox reactions (between PtII and PtIV) that allow for large conformational changes. Their reactivity, together with their host performance, is a convenient way to control the capture and release of guests, to mediate ring transformations, and to control pseudorotaxane‐to‐pseudorotaxane conversions. This novel approach could serve to assemble other libraries of small ring molecules, create cyclic polymers bridged by responsive‐at‐metal nodes, and produce processable mechanically interlocked molecules. [ABSTRACT FROM AUTHOR]

Urinary potassium is an important parameter in clinical health diagnosis. Rapid and convenient detection of potassium ions (K+) in urine is essential for personal healthcare and health management. Here, crown ether (4-aminodibenzo-18-crown-6, ADC) modified silver nanoparticles (ADC-Ag NPs) were successfully prepared for one-step rapid colorimetric detection of urinary potassium. The detection mechanism is as follows: due to the matching sizes of the diameter of K+ and the cavity in crown ether 6, K+ is encapsulated between the cavities of two crown ethers, resulting in the clumping of ADC-Ag NPs and the color of the solution being altered. The colorimetric detection method has a fast response and is completed within 20 minutes. It also shows good selectivity and interference immunity. The lowest detectable concentration is 20 μM with the naked eye and 2.16 μM for UV-vis absorption spectroscopy. A good linear relationship (R2 = 0.9931) between the absorption intensity ratio and K+ concentration (0–100 μM) indicates that this colorimetric probe can be used to detect K+. The method was also applied for quantitative analysis of K+ in real urine samples with recovery between 116 and 120%. [ABSTRACT FROM AUTHOR]

(1,6)Pyrenophanes 1 and 2 in which 1,6-positions of pyrene are bridged with respective tri- and tetra-ethylene glycol chains were synthesized. Addition of Ba(ClO4)2 to a 10−5 M CH2Cl2 : CH3CN = 1 : 1 solution of 1 reduced the intramolecular excimer emission with a maximum at 480 nm and increased the monomer emission around 370–400 nm. In contrast, addition of Ba(ClO4)2 to the solution of 2 shifted the intramolecular excimer emission to shorter wavelengths. Addition of n-Bu2NH2+PF6− to the solutions of 1 and 2 both decreased the intramolecular excimer emission and increased the monomer emission. Based on the results of these fluorescence changes, Job's plots, and NMR titration, it is concluded that 1 forms a 1 : 1 sandwich-type complex with Ba2+, 2 forms a 1 : 2 dumbbell-type complex with Ba2+, and both 1 and 2 form pseudorotaxanes with n-Bu2NH2+. It was also found that when the pyrenophanes 1 and 2 were mixed with tetracyanoethylene (TCNE) in CH2Cl2, charge-transfer (CT) complexes were formed, that exhibited absorption maxima at 740 and 744 nm, respectively. [ABSTRACT FROM AUTHOR]

Sodium (Na) metal anodes suffer from dendrite formation and inferior reversibility, mainly induced by the inhomogeneous nucleation/growth and fragile solid electrolyte interphase (SEI), which hinders their commercial application. Optimizing nucleation behavior or SEI features can improve Na deposition/stripping process, as observed in most currently available approaches, but its long‐term cyclic stability remains a great challenge because these issues are not fully optimized/solved in an individual method. Herein, a dual‐role crown ether additive (CEA) is introduced into electrolytes to circumvent these challenges concurrently. As revealed by experiments and theoretical calculations, CEA possesses a strong affinity with Na+ and effectively regulates desolvation kinetics, leading to the uniform Na nucleation/growth. On the other hand, the resultant Na+/CEA complexes with a strong Lewis acid feature easily attract anions, which enables an anion‐abundant solvation sheath, resulting in a NaF‐rich SEI. Consequently, Na|Cu cells deliver a high average Coulombic efficiency of 99.95% beyond one year and stable cyclic stability over 3000 h even under a high depth of discharge (75%), surpassing most previous studies. Furthermore, this concept is readily extended to zinc metal batteries, verifying that simultaneous nucleation control and interfacial chemistry regulation are promising ways to realize stable metal anodes. [ABSTRACT FROM AUTHOR]

Over the past two decades, non‐covalent chemistry has introduced various promising artificial receptors and revolutionized the host‐guest chemistry. These versatile receptors have particularly been entertained in sensing and recognizing of diverse neutral molecules and/or ionic entities (e. g. anions, cations and ion‐pair) of particular interest. Notably, supramolecular chemistry had given birth to a plethora of important molecules, explored in the chemical, biological, environmental, and pharmacological world to resolve the critical issues related to the human health while keeping environmental concerns in mind. Amongst the various types of supramolecular monotopic receptors (anions, cations, and neutral molecules), heteroditopic receptors (ion‐pair receptors) consisting of distinct binding sites in one system for both cation and anion, have gained much interest from the scientific community in recent past because of their unique binding abilities. Interestingly, these promising artificial receptors have shown potential applications in sensing, recognition, transport and extraction processes besides their uses in salt/waste purification. Bearing the importance of these systems in mind, we intended to report the recent developments in ion‐pair chemistry. Herein, we divided the whole document into three main sections; first one describes the introduction and history of the ion‐pairs receptors. The second portion highlights the synthesis and applications of ion‐pair receptors in sensing, recognition, molecular machines, photoswitching behaviour, extraction and transport properties, whereas the last part of this manuscript provides concluding remarks as well as future prospects of ion‐pair receptors. We hope that this manuscript will be helpful to stimulating researchers around the globe to find out the hidden opportunities in this and related areas. [ABSTRACT FROM AUTHOR]

A novel supramolecular complex Li3Cl[(HPW12O40)(H24C12O6)3(CH3CN)2] {CR-PW12} was confirmed first to apply as a sulfur host in lithium–sulfur batteries. The {CR-PW12}@S cathode exhibits a reversible capacity of 1120 mA h g−1 at 1.0 C and excellent cycle stability. [ABSTRACT FROM AUTHOR]

Estradiol (E2) plays an important role in the progression of diseases such as breast cancer and endometriosis. Inhibition of 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1), the enzyme that catalyzes the last step in the biosynthesis of the estrogenic hormone E2, therefore constitutes an interesting approach for the treatment of these two estrogen-dependent diseases. In order to obtain new inhibitors of 17β-HSD1, the impact of a m-carbamoylphenyloxy group at position three of an estrane nucleus was evaluated by preparing three derivatives of estrone (E1) and E2 using a microwave-assisted synthesis of diaryl ethers. Their inhibitory activity was addressed on two cell lines (T-47D and Z-12) representative of breast cancer and endometriosis, respectively, but unlike T-47D cells, Z-12 cells were not found suitable for testing potential 17β-HSD1 inhibitors. Thus, the addition of the m-carbamoylphenyl group at C3 of E1 (compound 5) did not increase the inhibition of E1 to E2 transformation by 17β-HSD1 present in T-47D cells (IC50 = 0.31 and 0.21 μM for 5 and E1, respectively), and this negative effect was more obvious for E2 derivatives 6 and 10 (IC50 = 1.2 and 1.3 μM, respectively). Molecular docking allowed us to identify key interactions with 17β-HSD1 and to highlight these new inhibitors' actions through an opposite orientation than natural enzyme substrate E1′s classical one. Furthermore, molecular modeling experiments explain the better inhibitory activity of E1-ether derivative 5, as opposed to the E2-ether derivatives 6 and 10. Finally, when tested on T-47D and Z-12 cells, compounds 5, 6 and 10 did not stimulate the proliferation of these two estrogen-dependent cell lines. In fact, they reduced it. [ABSTRACT FROM AUTHOR]

Peroxisomes are essential metabolic organelles, well known for their roles in the metabolism of complex lipids and reactive ionic species. In the past 10 years, peroxisomes have also been cast as central regulators of immunity. Lipid metabolites of peroxisomes, such as polyunsaturated fatty acids (PUFAs), are precursors for important immune mediators, including leukotrienes (LTs) and resolvins. Peroxisomal redox metabolism modulates cellular immune signaling such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation. Additionally, peroxisomal β-oxidation and ether lipid synthesis control the development and aspects of the activation of both innate and adaptive immune cells. Finally, peroxisome number and metabolic activity have been linked to inflammatory diseases. These discoveries have opened avenues of investigation aimed at targeting peroxisomes for therapeutic intervention in immune disorders, inflammation, and cancer. Peroxisomes are important metabolic regulators of immune cell development and function. Peroxisomes produce distinct lipids that control core cellular immune responses, including phagocytosis and secretion of inflammatory cytokines. Peroxisomes regulate cellular reactive oxygen and nitrogen species to modulate immune and inflammatory signaling. Intracellular pathogens interfere with peroxisomes in different ways to evade the peroxisome-dependent immune response and support their survival. Manipulation of peroxisome plasticity and metabolism may lead to novel therapeutics to treat immune disorders and antibiotic-resistant bacteria. [ABSTRACT FROM AUTHOR]

A new type of potentiometric sensor for cesium ions based on a crown ether (dibenzo-21-crown-7) is proposed; its analytical characteristics are presented: limit of detection, slope of electrode function, selectivity to a number of interfering ions, and the working pH range of solutions. [ABSTRACT FROM AUTHOR]

Molecular imprinting technology（MIT） has predetermination, recognition and usability, and has been widely used in chromatographic separation， solid phase extraction, drug analysis, chiral recognition and other fields. In recent years， researchers have introduced macrocyclic compounds into MIT， which not only increases the types of functional monomers， but also effectively improves the specificity of molecularly imprinted polymers and the selectivity of target molecules. In this paper， the research progress and application of macrocyclic compounds such as cyclodextrin， calixarene， pillararene， crown ether, cucurbituril and other supramolecular compounds in MIT in the past ten years are reviewed and its development prospects are prospected. [ABSTRACT FROM AUTHOR]

Background. An alternative to the extraction of copper ions with liquid organic extractants are "dry" ones: crown ethers, cryptands, etc., which do not require the use of solvents, their subsequent removal and regeneration. Purpose: to develop a new method for the detection and extraction of copper ions using the solid extractant 4',4"-di-(3-hydroxypentynyl)-dibenzo-18-crown-6 ether. Methodology. The distribution coefficient of copper (II) was determined by conductometry and photometry, the structure of the complex was confirmed by IR and Roman spectroscopy. Originality. A new method for detecting and extracting copper (II) using the solid extractant 4',4"-di-(3-hydroxypentynyl)-dibenzo-18-crown-6 ether has been developed. Findings: the complexation of copper (II) ions with 4',4"-di-(3-hydroxypentynyl)-dibenzo-18-crown-6 ether was studied based on the intensity of the vibrational frequencies of ether bonds in the IR and Roman spectra in the region of 1000 -1500 cm-1. The new reagent is used as a solid extractant for extracting microconcentrations of copper (II) from wastewater. [ABSTRACT FROM AUTHOR]

In‐depth understanding of copolymerization kinetics and the resulting polymer microstructure is crucial for the design of materials with well‐defined properties. Further, insights regarding the impact of solvents on copolymerization kinetics allows for precisely tuned materials. In this regard, in situ 1H NMR spectroscopy enables precise monitoring of the living anionic ring‐opening copolymerization (AROP) of ethylene oxide (EO) with the glycidyl ethers allyl glycidyl ether (AGE) and ethoxy vinyl glycidyl ether (EVGE), respectively. Determination of reactivity ratios reveals slightly higher reactivity of both glycidyl ethers compared to EO, emphasizing a pronounced counterion chelation effect by glycidyl ethers in AROP. Implementation of density functional theory (DFT) calculations further illustrates the complexation capability of ether‐containing side groups in glycidyl ethers, in analogy to crown ethers ("crown ether effect"). Investigation of the copolymerization in i) THF‐d8 and ii) DMSO‐d6 shows an increasing disparity of reactivity ratios for both glycidyl ethers compared to EO, clearly related to decreasing solvent polarity. [ABSTRACT FROM AUTHOR]

Due to the relative abundance, long half-life and high mobility of radioactive cesium (Cs), new adsorbents are urgently needed to treat Cs to ensure public health. In this study, a graphene oxide (GO) based adsorbent for Cs(I) adsorption was prepared by 1-aza-18-crown-6 ether modification. XRD, FT-IR, XPS and SEM results showed that the properties of 1-aza-18-crown 6 ether modified GO (18C6-GO) changed dramatically compared with that of raw graphite. The adsorption properties of 18C6-GO for Cs(I) were studied by batch static adsorption experiments. The results showed that the adsorption equilibrium time of 18C6-GO was 20 h. Kinetic study revealed that the adsorption rate of Cs(I) conformed to pseudo-second-order kinetic model. Langmuir adsorption isotherm simulation indicated that the adsorption arises at homogeneous adsorption sites on 18C6-GO. Therefore, crown ether modified GO may have implications for the treatment of wastewater. [ABSTRACT FROM AUTHOR]

Functionalization of fullerene via covalent addition of substituted 4-benzo-9-crown-3 ether diazonium salt has been described. This procedure is used for the preparation of new derivative fullerenes which is described as a phase transfer catalyst. The covalent grafting has led to a considerable increment in the solubility of fullerene in organic solvents such as, CH2Cl2, acetone and ethanol. The covalent grafting of crown ether (4-(benzo-9-crown-3)) to fullerene (Fullerene-CE) has been identified and confirmed by IR, H-NMR, 7Li-NMR and thermogravimetric analysis (TGA) methods. Fullerene-CE in solvents has been used as a phase transfer catalyst for organic reactions. The Fullerene-CE is capable to become the Li+ host. [ABSTRACT FROM AUTHOR]

This article presents the synthesis and molecular dynamics investigation of three novel cyclic thioethers: 2,3-(4′-methylbenzo)-1,4,7,10-tetrathiacyclododeca-2-ene (compound 1), 2,3,14,15-bis(4′,4″(5″)-methylbenzo)-1,4,7,10,13,16,19,22,25-octathiacyclotetracosa-2,14-diene (compound 2), and 2,3,8,9-bis(4′,4″(5″)-methylbenzo)-1,4,7,10-tetrathiacyclododeca-2,8-diene (compound 3). The compounds exhibit relatively high glass transition temperatures (Tg), which range between 254 and 283 K. This characteristic positions them within the so-far limited category of crown-like glass-formers. We demonstrate that cyclic thioethers may span both the realms of ordinary and sizeable molecular glass-formers, each featuring distinct physical properties. Furthermore, we show that the Tg follows a sublinear power law as a function of the molar mass within this class of compounds. We also reveal multiple dielectric relaxation processes of the novel cyclic thioethers. Above the Tg, their dielectric loss spectra are dominated by a structural relaxation, which originates from the cooperative reorientation of entire molecules and exhibits an excess wing on its high-frequency slope. This feature has been attributed to the Johari–Goldstein (JG) process. Each investigated compound exhibits also at least one intramolecular secondary non-JG relaxation stemming from conformational changes. Their activation energies range from approximately 19 kJ/mol to roughly 40 kJ/mol. Finally, we analyze the high-pressure molecular dynamics of compound 1, revealing a pressure-induced increase in its Tg with a dTg/dp coefficient equal to 197 ± 8 K/GPa.

This mini-review summarizes the seminal exploration of aqueous supramolecular chemistry of crown ether macrocycles. In history, most research of crown ethers were focusing on their supramolecular chemistry in organic phase or in gas phase. In sharp contrast, the recent research evidently reveal that crown ethers are very suitable for studying abroad range of the properties and applications of water interactions, from: high water-solubility, control of Hofmeister series, “structural water”, and supramolecular adhesives. Key studies revealing more details about the properties of water and aqueous solutions are highlighted.

A multicolor room temperature phosphorescence (RTP) supramolecular photo‐switch encryption film is constructed by the coassembly of coumarin‐24‐crown‐8 (C24C8), diarylethene dicationic alkylammonium derivative (1), rhodamine B (RhB) and poly(vinyl alcohol) (PVA). Benefiting from the tightly binding of C24C8 and secondary alkylammonium ion, 1 formed noncovalent bridged bis(coumarin‐24‐crown‐8), which displayed photo‐switchable RTP with green afterglow (more than 5 s) after coassembly with PVA. Especially doping with RhB gave a photo‐switchable highly efficient phosphorescence‐harvesting system with multicolor through triplet‐to‐singlet Förster‐resonance energy transfer (TS‐FRET). The energy transfer efficiency and antenna effect of C24C8+RhB@PVA film reached 88.3% and 62.6 when the donor/acceptor ratio is 50:1, respectively. Therefore, diarylethene noncovalent bridged bis(coumarin‐24‐crown‐8) supramolecular assembly not only displays a multicolor photoluminescence‐switch, but also presents a phosphorescent photo‐switch with afterglow, which provides a simple and feasible way to construct smart RTP materials through host‐guest strategy. [ABSTRACT FROM AUTHOR]

Luminescent probes have wide applications in biological system analysis and environmental science. Here, one novel luminescent dinuclear europium compound with a crown ether analogous ligand was synthesized through a solvent–thermal reaction. Through transformation, upon the addition of Al3+ ions to the N,N′-dimethyl formamide solution of the europium compound, the luminescent intensity of the characteristic emission of Eu3+ decreased, and a new emission peak appeared at 346 nm and increased rapidly. The luminescent investigation indicated that it could act as a highly sensitive and selective luminescent probe for Al3+ ions. Moreover, mass spectrometry and single-crystal X-ray diffraction confirmed the formation of a new more stable trinuclear aluminium compound during the sensing process. [ABSTRACT FROM AUTHOR]

Crownphyrins are hybrid macrocycles combining structural features of porphyrin and crown ethers. The molecular architecture renders them an intriguing class of hosts capable of binding neutral, and ionic guests. The presence of dynamic covalent imine linkages connecting the dipyrrin segment with the ether chain enables unusual coordination behavior of crownphyrins, as demonstrated by the formation of two classes of strikingly different complexes. The remarkable metal‐mediated expansion to the helical [2+2] macrocyclic complex is reversible. The reaction of the figure‐eight mercury(II) assembly with [2.2.2]cryptand results in ring contraction providing the metal‐free crownphyrin macrocycle. [ABSTRACT FROM AUTHOR]

Nitrobenzofurazan derivatives are well known for their fluorescence, whilst crown ethers are known for their complexing capacity toward cationic species. In this study, we present the synthesis and structural characterization of a new derivative containing both nitrobenzofurazan moieties and a crown ether core. The new compound was obtained from dibenzo-18-crown-6 ether, which was first nitrated, reduced to the corresponding amine, and subsequently derivatized with NBD. Structural analyses performed by IR, NMR, UV–Vis, and MS confirmed its structure and physico-chemical behavior toward the complexation of alkaline cations. [ABSTRACT FROM AUTHOR]

The reaction of potassium (aza-15-crown-5)dithiocarbamate (KO4NCS2) and (Me2S)AuCl gave the dinuclear complex [Au(O4NCS2)]2, which underwent structural transformation upon heating to rearrange into the hexanuclear complex [Au(O4NCS2)]6. Under similar reaction conditions, KO4NCS2 reacted with AgNO3 or [Cu(CH3CN)4]ClO4 to give the 1-D coordination polymer [Ag(O4NCS2)]n (1) and the tetranuclear complex [Cu(O4NCS2)]4 (2), respectively. It is noted that upon heating a similar structural transformation process occurs from tetranuclear complex 2 to the octanuclear complex [Cu(O4NCS2)]8 (2′), connected by a weak Cu⋯S contact of 2.846 Å, and it has been isolated and corroborated by powder and single-crystal X-ray diffraction studies as well. Moreover, a variety of MO4NCS2 salts (M = Li+, Na+, K+ and Rb+) were used to react with AgNO3 to construct a series of coordination architectures: [LiAg(O4NCS2)2(μ-H2O)0.5]2 (3), {Na[Ag(O4NCS2)2]}n (4), {K[Ag(O4NCS2)2]}n (5) and {Rb[Ag(O4NCS2)2]}n (6). The smallest Li+ ion only coordinates with four oxygen atoms from the same azacrown ether ring and one H2O molecule, leading to a 1-D hydrogen-bonded chain with another azacrown ether ring for complex 3. The larger Na+ ion coordinates with seven oxygen atoms from two different crown ether rings, leading to a 1-D chain for complex 4. However, the largest K+ and Rb+ ions constitute a 1-D framework, except that each metal ion coordinates with eight oxygen atoms from two different crown ether rings, featuring a 1-D helical chain for complexes 5 and 6. Hence, the different sizes of alkaline metal ions exert a dramatic effect on the structural motifs of complexes 3–6. Remarkably, the dithiocarbamate moieties adopt μ2-bridging ([Au(O4NCS2)]2 and [Au(O4NCS2)]6), μ3- and μ4-bridging (1–2) and chelate forms (3–6) in the structural backbones. [ABSTRACT FROM AUTHOR]

The Lewis superacid bis(perchlorocatecholato)silane catalyzes C−O bond metathesis of alkyl ethers with an efficiency outperforming all earlier reported systems. Chemoselective ring contractions of macrocyclic crown ethers enable substrate‐specific transformations, and an unprecedented ring‐closing metathesis of polyethylene glycols allows polymer‐selective degradation. Quantum chemical computations scrutinize a high Lewis acidity paired with a simultaneous low propensity for polydentate substrate binding as critical for successful catalysis. Based on these mechanistic insights, a second‐generation class of silicon Lewis superacid with enhanced efficacy is identified and demonstrated. [ABSTRACT FROM AUTHOR]

The crown ether strontium extraction (CESE) process has been developed for the recovery or removal of Sr from acidic high-level liquid waste (HLLW) in China, where the extractant is 4',4"(5")-di-(tert-butyldicyclohexano)-18-crown-6 (DtBuCH18C6) and the diluent is n-octanol. When the CESE process was operated in annular centrifugal extractors (ACEs) for demonstration by cold and hot tests, it was found that the outlet aqueous phases had organic-phase entrainment even though ACEs operated at a low rotor speed. For the successful operation of the CESE process in ACEs, effects of the operating and geometrical parameters on the liquid hold-up volume and phase ratio (aqueous phase/organic phase, A/O) of the HNO3–DtBuCH18C6/n-octanol system in a ϕ20 ACE were systematically investigated to find the cause of the above-mentioned hydrodynamic performance problem of the CESE process using the liquid-fast-separation method. It is shown that the operating and geometrical parameters have effects on the liquid hold-up volume and phase ratio (A/O). Moreover, the phase ratio (A/O) in the separation zone of the rotor is less than 1.5 under most of the present experimental conditions, which shows organic-phase entrainment may easily occur in the outlet aqueous phase. The cause can be that the density difference of two phases is small, viscosity of the organic phase is large, and interfacial tension of the extraction system is low. [ABSTRACT FROM AUTHOR]

The extraction of cesium, strontium, and a number of stable components of simulated high-level waste solutions from nitric acid media with solutions of crown ether derivatives in new fluorinated diluents was studied. Based on the data on the solubility of the extractants into the aqueous phase and the physicochemical properties of the diluents used, the most promising extraction systems were chosen: crown ethers 4,4'(5')-di-tert-butyldibenzo-18-crown-6 (L1) and 4,4'(5')-di-tert-butyldicyclohexyl-18-crown-6 (L2) in bis(2,2,3,3-tetrafluoropropyl) carbonate (BK-1) and bis(2,2,3,3-tetrafluoropropoxy)methane (FN-1). For these systems, the extraction of a number of stable components and their subsequent stripping with water and solutions of chelating agents were studied. Lead was found to be co-extracted to the greatest extent. To a lesser extent, barium and calcium cations are co-extracted with strontium, and rubidium and potassium cations with cesium. Lead, barium, and silver are the most difficult to strip; however, the problem of lead stripping can be solved by using DTPA or citric acid solutions neutralized with ammonia to weakly alkaline (pH 8) media. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) plays a vital role in regulating many important physiological functions. However, H2S-containing industrial wastewater is inevitably pumped into the environment which seriously contaminates water supplies and foodstuffs. So it is crucial to develop a single fluorescent probe for H2S detection with high sensitivity and selectivity. Herein, a colorimetric and turn-on near infrared (NIR) fluorescent probe NRDNP based on benzophenoxazine was designed and synthesized by thiolysis of 2,4-dinitrophenyl (DNP) ether as the specific reaction site strategy to achieve highly specific H2S detection in living systems. The studies demonstrated that the probe NRDNP exhibited excellent sensing performance toward H2S with an about 80-fold NIR fluorescence enhancement, a rapid response within 10 min, excellent sensitivity with a detection limit of 19 nM and good selectivity. Furthermore, the NRDNP is an optical sensor which visually changes in terms of the fluorescence colour/intensity upon sensing gaseous H2S molecules. NRDNP has low cytotoxicity and has been successfully applied in the fluorescence imaging of H2S in living cells, suggesting that it would be an effective tool for H2S detection in living systems. [ABSTRACT FROM AUTHOR]

The excellent properties of host–guest crown ether inclusions in phase transition, dielectric and second-order nonlinear optical properties have attracted much attention. In this paper, we successfully designed and prepared two novel host–guest crown ether supramolecules [(DFBA)(15-crown-5)]X (X = ClO4−, 1; ReO4−, 2) by reactions of 2,6-difluorobenzylamine (DFBA) with 1,4,10,13-pentaoxacyclopentadecane (15-crown-5) in HClO4, or HReO4 aqueous solution. By the introduction of difluoro-substituted benzylamine as a guest cation, the phase transition temperatures are greatly increased to 377 K for 1 and 391 K for 2. More importantly, the space group of 1 has changed from centrosymmetric (CS) P2/c to the non-centrosymmetric (NCS) Pca21 in 2 when substituting perchlorate (ClO4−) with the larger and heavier perrhenate (ReO4−), which leads to 2 showing a switchable and stable second-harmonic generation (SHG) effect. According to the principle of momentum matching between a cation and anion, the perrhenate group increases the energy barrier of the molecular thermal motion, which not only significantly increases the phase transition temperature of 2 but also causes it to be frozen and crystallized in a NCS space group at room temperature. This research demonstrates that a polar molecule can adjust the suitability of anions and cations inside the crystal by practical chemical means. [ABSTRACT FROM AUTHOR]

The oxyanionic ring‐opening polymerization of propylene oxide (PO) from an exogenous alcohol activated with benign (complexed) metal‐alkali carboxylates is described. The equimolar mixture of potassium acetate (KOAc) and 18‐crown‐6 ether (18C6) is demonstrated to be the complex of choice for preparing poly(propylene oxide) (PPO) in a controlled manner. In the presence of 18C6/KOAc, hydrogen‐bonded alcohols act as soft nucleophiles promoting the PO SN2 process at room temperature and in solvent‐free conditions while drastically limiting the occurrence of parasitic hydrogen abstraction generally observed during the anionic ROP of PO. The resulting PPO displays predictable and unprecedented molar masses (up to 20 kg mol−1) with low dispersities (ĐM < 1.1), rendering the 18C6/KOAc complex the most performing activator for the oxyanionic polymerization of PO reported to date. Preliminary studies on the preparation of block and statistical copolyethers are also reported. [ABSTRACT FROM AUTHOR]

The solid-state behaviour of five ionophore-encapsulated TCNQ complexes: (18-crown-6)K(TCNQ)2.5 (1), ([2.2.2]-cryptand)K(TCNQ)2.5 (2), (benzo-18-crown-6)K(TCNQ)2 (3), (dibenzo-18-crown-6)K(TCNQ)2 (4), and (dicyclohexano-18-crown-6)K(TCNQ)3 (5) has been explored. For both 1 and 2, the TCNQ components assemble as a pentameric repeat unit within infinite TCNQ columns with the cation complex sitting in a cavity between the columns; whereas for 3 and 4, neighbouring (crown ether)K+ complexes form dimers involving K+–π interactions which further assemble into one-dimensional columns sitting between infinite TCNQ stacks. In the solid-state complex 5, the crown ether adopts a chair conformation with the resulting (crown ether)K+ complex assembling into a one-dimensional ladder. Pairs of TCNQ dimers separated by an isolated TCNQ unit form infinite TCNQ columns. IR and Raman spectroscopy reveal the presence of partially charged TCNQ units within all five TCNQ complexes (1–5) and resistivity studies indicate that all five TCNQ complexes (1–5) are more conductive than the corresponding simple KTCNQ salts. Preliminary EPR studies of 1 and 2 indicate typical behaviour of complex TCNQ salts (containing both TCNQ0 and TCNQ˙−). [ABSTRACT FROM AUTHOR]

Developing hierarchical ordered systems is challenging. Using organo-macrocycles to construct metal–organic frameworks (MOFs) and porous coordination cages (PCCs) provides an efficient way to obtain hierarchical assemblies. Macrocycles, such as crown ethers, cyclodextrins, calixarenes, cucurbiturils, and pillararenes, can be incorporated within MOFs/PCCs and they also endow the resultant composites with enhanced properties and functionalities. This review summarizes recent developments of organo-macrocycle-containing hierarchical MOFs/PCCs, emphasizing applications and structure–property relationships of these hierarchically porous materials. This review provides insights for future research on hierarchical self-assembly using macrocycles as building blocks and functional ligands to extend the applications of the composites. [ABSTRACT FROM AUTHOR]

Ammonium ion/carboxylate ion pairing is a key interaction ubiquitous in biological systems, but amine recognition by ionizable molecular receptors, mediated by host-to-guest proton transfer, has too often been overlooked as a design element for molecular recognition. This survey will show that proton transfer mediated recognition is a powerful and versatile tool that can be made to work with different amines and diverse macrocyclic scaffolds, such as crown ethers, calixarenes or pillararenes. We will trace the history of this recognition motif since Cram's first report half a century ago down to the latest applications in supramolecular sensing, drug-delivery and materials science, highlighting along the way the impact of host-to-guest proton transfer on self-assembly and molecular recognition. [ABSTRACT FROM AUTHOR]

Fluorescent molecules absorb photons of specific wavelengths and emit a longer wavelength photon within nanoseconds. Recently, fluorescent materials have been widely used in the life and material sciences. Fluorescently labelled heterocyclic compounds are useful in bioanalytical applications, including in vivo imaging, high throughput screening, diagnostics, and light-emitting diodes. These compounds have various therapeutic properties, including antifungal, antitumor, antimalarial, anti-inflammatory, and analgesic activities. Different neutral fluorescent markers containing nitrogen heterocycles (quinolones, azafluoranthenes, pyrazoloquinolines, etc.) have several electrochemical, biological, and nonlinear optic applications. Photodynamic therapy (PDT), which destroys tumors and keeps normal tissues safe, works in the presence of molecular oxygen with light and a photosensitizing drugs (dye) to obtain a therapeutic effect. These compounds can potentially be effective templates for producing devices used in biological research. Blending crown compounds with fluorescent residues to create sensors has been frequently investigated. Florescent heterocyclic compounds (crown ether) increase metal solubility in non-aqueous fluids, broadening the application window. Fluorescent supramolecular polymers have widespread use in fluorescent materials, fluorescence probing, data storage, bio-imaging, drug administration, reproduction, biocatalysis, and cancer treatment. The employment of fluorophores, including organic chromophores and crown ethers, which have high selectivity, sensitivity, and stability constants, opens up new avenues for research. Fluorescent organic compounds are gaining importance in the biological world daily because of their diverse functionality with remarkable structural features and positive properties in the fields of medicine, photochemistry, and spectroscopy. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) is a major concern for the survival of mankind. COVID-19 accelerated another silent pandemic of AMR through the uncontrolled use of antibiotics and biocides. New generations of antimicrobial agents are needed to combat resistant pathogens. Crown ethers can be used as models for drug action because they are similar to antibiotics. Iodine is a well-known microbicide but is characterized by instability and short-term effectivity. Iodine can be stabilized in the form of polyiodides that have a rich topology but are dependent on their immediate surroundings. In addition, copper has been successfully used since the beginning of history as a biocidal agent. We, therefore, combined iodine and copper with the highly selective crown ether 1,4,7,10-tetraoxacyclododecane (12-crown-4). The morphology and composition of the new pentaiodide [Cu(12-crown-4)2]I5 was investigated. Its antimicrobial activities against a selection of 10 pathogens were studied. It was found that C. albicans WDCM 00054 is highly susceptible to [Cu(12-crown-4)2]I5. Additionally, the compound has good to intermediate antimicrobial activity against Gram-positive and Gram-negative bacilli. The chain-like pentaiodide structure is V-shaped and consists of iodine molecules with very short covalent bonds connected to triiodides by halogen bonding. The single crystal structure is arranged across the lattice fringes in the form of ribbons or honeycombs. The susceptibility of microorganisms towards polyiodides depends on polyiodide bonding patterns with halogen-, covalent-, and non-covalent bonding. [ABSTRACT FROM AUTHOR]

Nitropyridine substituted double-armed benzo 15-crown-5 compounds (1–4) were synthesized by the reactions of 4′,5′-bis(bromomethyl)benzo-15-crown-5 with hydroxypyridine derivatives. Na+ and K+ complexes (1a–4a, 1b–4b) of crown ether compounds (1–4) were prepared with sodium picrate and potassium picrate, respectively. Transition metal complexes (1c–4c) of the synthesized ligands (1–4) were prepared from Ag+ cation. In addition, nitro compounds (1, 2 and 4) were reduced by using Pd/C and hydrazine hydrate and new amine compounds (5, 6 and 8) were obtained. The structures of new double-armed crown ether compounds (2–4), their metal complexes (1a–4a, 1b–4b, 2c–4c) and amine compounds (5, 6 and 8) were elucidated by FTIR, HRMS, 1H–NMR, 13C–NMR spectroscopic methods. The thermal behaviors of these nitro group containing ligands (1–4) were compared with the resulting silver complexes (1c–4c) and amine compounds (5, 6 and 8). All synthesized compounds were examined for antibacterial activity against pathogenic strains Listeria monocytogenes, Salmonella typhi H, Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Escherichia coli, Klebsiella pneumonia, Proteus vulgaris, Serratia marcescens, Shigella dysenteria and antifungal activity against Candida albicans. [ABSTRACT FROM AUTHOR]

K[(18-crown-6)-bis(tetrahydrofuran)anthracenide] was independently prepared by three groups, and its structure described by two of them. The third structure description, though listed in the Cambridge Crystallographic Data Centre (CSD) collection, contains no space group or atomic coordinates, but the cell constants leave no doubt that it is the same species as the two others, which were reported in 2006 and 2016. The compound crystallizes in space group P21, with Z′ = 2.0 at T = 123 K and R = 4.91% (I), and at 100 K and R = 4.44% (II); both impressive results in their individual quality and agreement, despite differences in experimental methods and the temperature of data collection. A more detailed examination of the published data for (I) and (II) reveals that the correct description for this very unusual, and thus far unique substance, is that it contains a radical anion crystallizing as a kryptoracemate rather than as a simple example of a Sohncke space group with Z′ = 2.0. The anthracenide anions present in (I) and (II) are virtually identical; in contrast, the internal pair of cationic species differ from one another in the dissymmetry of the flexible tetrahydrofuran ligands, having significantly different internal and external torsional angles. The two THF molecules attached to the K(crown-ether) cations are not centrosymmetrically related, and this is what makes this portion of the asymmetric unit responsible for the crystal being a kryptoracemate. Our presentation will be based on the more fully documented sample (II), unless specifically stated.

• Compilation of important results of investigations of the complexation chemistry, characterization, stability and photophysical properties of complexes of small ring benzo-oxa-crown ethers namely benzo15-crown-5, dibenzo-15-crown-5 and benzo-12-crown-4 with alkali metal ions in the solution state. • Results from techniques like UV, far-IR, Raman, 1H, 13C and multinuclei NMR that have been employed to confirm the formation of the complexes and designate their conformers in solution state are included in the review. • The solvent systems and binary and ternary mixtures of solvents employed to study these complexes have been reported in this review. • The complexation thermodynamics and results of experiments based on conductance properties, fluorescence responses and energy transfer mechanisms are also discussed in this paper. This review paper focuses on the past and recent investigations carried out in solution state to determine the complexation chemistry, characterization, stability and photophysical properties of complexes of small ring benzo oxa-crown ethers namely benzo - 15-crown-5, dibenzo-15-crown-5 and benzo-12-crown-4 with alkali metal ions. These crown ethers form stable complexes with physiologically important ions like Li+, Na+ and K +and mimic natural ionophores in this property. The experimental observations from UV–visible spectroscopy, IR spectroscopy, NMR spectroscopy, conductometry and calorimetry are useful in confirming the formation of these complexes. In addition to monitoring the complexation process, techniques like IR and NMR spectroscopy have helped to designate the conformers of the complexes in solution. These crown ethers have been used in developing functional materials such as ion sensors, fluorescent logic gates, oil/water emulsion separating agents and extractors of toxic ions like cesium from nuclear waste. The benzene moiety in these macrocycles enables them to act as fluorescent sensors for alkali metal ions. They make ideal candidates to anchor on nanoparticles for sensing alkali metal ions. The ring current in the benzene ring of benzo-crown ethers makes the carbon and protons nonequivalent and hence easily distinguishable by methods like 1H and 13C NMR spectroscopy as compared to 12-crown-4 and 15-crown-5. The solvent systems including binary and ternary mixtures of solvents employed in the study of these complexes have been reported in this review. Important aspects of complexation thermodynamics, fluorescence intensity altering processes and energy transfer mechanisms are also discussed in this paper. The dielectrics and donicity of the medium form an additional aspect of the review. These crown ethers form supramolecular assemblies with alkali metal halides and can therefore serve as good models to study and explore suitability of characterization methods for noncovalent interactions. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Brief discussion of lithium reserves, resources, and technologies currently in practice toward extraction of lithium. • Exploration of lithium-selective organic receptors, their photo-physical studies, mechanism of interaction, and extraction from different sources. • Advantages of organic receptors and their scope towards lithium sensing and extracting from sea brine and battery e-waste. • Addressing challenges and presenting future perspectives for organic receptors towards extraction of lithium-ion on a large scale and even from dilute sources. The rising global demand for lithium and its compounds has led to a shift away from fossil fuels towards more energy-efficient systems like lithium-ion batteries (LIBs). Various technologies and materials are being explored for mining and extracting lithium, but current methods like solar evaporation and critical mining are slow and deplete resources rapidly. Therefore, there is a growing need for recycling used lithium. While some multi-passive technologies show promise, they often fall short in terms of cost-effectiveness, selectivity, and recyclability. Supramolecular receptors such as crown ethers, calixarenes, and their derivatives and more recently functionalized ionic liquids and deep eutectic solvents offer a potential solution to these challenges. Efforts are directed to create specialized supramolecular receptors that can both sense and extract lithium ion, particularly from challenging sources like sea-brine. Recent studies have highlighted the potential of silica-based materials and metal–organic frameworks (MOFs) in adsorption, but there is a need for further refinement to make them viable for real-world applications. Strategies involving post-modification and transforming receptors into MOFs or other materials hold promise in improving surface area and recyclability, thus enhancing their effectiveness. This review aims to compile all existing supramolecular receptors developed for lithium sensing and extraction, comparing them with newer generation receptors. It tries to summarize their selectivity towards lithium ions, describe their mechanisms, and extraction properties, providing a comprehensive resource for researchers working in this field. [ABSTRACT FROM AUTHOR]

The new class of ten macrocyclic compounds, lactic acid derived crown ethers, was designed and synthesized. They mainly composed of lactic acid and benzene or iodobenzene skeletons, and the introduction of iodine on the benzene ring was crucial to the formation of more regular crown ether conformation, starting from the diacid precursor. They possessed stable and larger cavities than classical macrocycles such as cyclodextrins. These crown ethers were discovered hiding function onto small molecules such as ethyl lactate, methanol, ethanol, aniline and phenol in nuclear magnetic resonance detection. [Display omitted] • New application of crown ethers in hiding small organic molecules. • The η was defined as the percentage of hidden molecules for the first time. • A new phenomenon in nuclear magnetic resonance testing. [ABSTRACT FROM AUTHOR]

Selective separation property enhancement is quite important for membranes separations, especially for high mass ratio Mg2+/Li+ separations. Low selectivity and unclear separation mechanism are the challenges for current membranes. In this study, we designed 4-aminophenyl-15-crown-5 incorporated polyamide nanofiltration membranes through interfacial polymerization for Li+ enrichment. The electrochemical tests and energy barrier calculations using transition state theory confirmed that the crown ether in nanofiltration membrane is responsible for governing Mg2+ transportation, resulting in a substantial energy barrier impeding its transport. Furthermore, a two-stage nanofiltration process was employed to enhance Li+ enrichment in simulated brine and achieved 35-fold increase in Li+ enrichment using as-fabricated membranes. These results demonstrate the substantial potential for Li + extraction from brine with a high Mg2+/Li+ mass ratio using the crown ether incorporated membrane. Meanwhile, the proposed strategy incorporating transport barriers presents a novel approach for designing ion-selective channels within membranes. [Display omitted] • A novel crown ether nanofiltration polyamide membrane was fabricated by interfacial polymerization (IP) process. • PEI@4A-B15C5 membrane has a great hindrance to Mg2+ transport. • Efficient enrichment of Li+ from a simulated brine. [ABSTRACT FROM AUTHOR]

A great challenge is to develop suitable techniques to extract Li+ resources from low-grade salt-lake brines with high Mg/Li ratios. In this study, an efficient ternary extraction system has been constructed using tributyl phosphate (TBP) and crown ether (CE) as the extractant and sodium bistrifluoromethylsulfonimide (NaNTf 2) as the auxiliary extractant to extract Li+. Results showed that the single-stage E Li % and SF Li-Mg were up to 74.1 % and 757, respectively, when the O/A was 1, 0.02 mol/l Li+ and 0.232 mol/l Mg2+. It is noteworthy that the elution of Li+ was also as high as 100 % at an O/A volume ratio of 5, when 0.5 mol/l HCl was used as the counter-extractant to recovery Li+. The NMR and FTIR analysis and molecular dynamics (MD) and density functional theory (DFT) revealed that the exceptional performance of the three-component extraction system was attributed to the optimal matching between the diameter of Li+ and the cavity size of the CE, as well as the strong affinity exhibited by CE, TBP, and NTf 2 − towards Li+. Specifically, the 2TBP-LiNTf 2 -CE-LiNTf 2 complex structure with the highest binding energy displayed the most structure. In summary, this work paves the way for the recovery of Li+ from low-grade salt-lake brine. [Display omitted] • The green ternary extraction system was constructed with TBP, CE and NaNTf 2. • The E Li % and SF Li-Mg of TBP-CE-NaNTf 2 were up to 74.1 % and 757, respectively. • The NTf 2 − readily forms the complexes with Li+ and TBP, CE. • The structure with 2TBP-LiNTf 2 -CE-LiNTf 2 is the most stable. • TBP and CE are more easily combined with NTf 2 − rather than Cl− to extract Li+. [ABSTRACT FROM AUTHOR]

• Sulfonated polyketone membranes functionalized with crown ethers are fabricated. • The synergistic ion channels are constructed by ion-binding and ion-exchange sites. • A separation factor for K+/Mg2+ over 40,000 in ion-distillation process is achieved. The specific interaction existing between crown ethers (CEs) and alkali metal ions serves a dual purpose in both facilitating the selective ion transport across polymeric membranes and exerting a significant influence on the microstructure by means of non-covalent interactions among the CEs. In this study, synergistic ion channels featuring a bi-periodic structure are constructed using both CEs and sulfonate (−SO 3 −) groups. It is observed that the membranes with reduced water uptake demonstrate enhanced ion permselectivity, attributable to the partial dehydration of ions during binding behavior. The bi-functional membranes exhibit excellent permselectivity for alkali metal ions, particularly K+, Na+ and Li+ ions, over Mg2+ ions. The permselectivity sequence of K+>Na+>Li+ and the notably superior K+/Mg2+ permselectivity, reaching up to 244.43, is attributed to the relatively stable CE-K+ complex within the channels, as supported by molecular dynamics simulations. Specifically, the fabricated membrane is successfully utilized in a 4-stage "ion-distillation" process, achieving an impressive separation factor for K+/Mg2+ over 40,000. The investigation of the synergy between CEs and anionic sites provides valuable insights for the development of cation-permselective membranes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recent developments of chalcogen-based fluorescent probes for metal ion detection are reviewed. • Comparison of different chalcogens in the same detection system are discussed. • Design strategies of chalcogen-based fluorescent probes for metal ion detection are summarized. Metal ion detection is notably significant in fields such as the biological sciences, clinical medicine, environmental chemistry, and food safety. In this regard, fluorescent probes have represented an important technique for the rapid detection of metal ions in various areas. As Lewis bases, chalcogen elements with high electron-donating ability provide versatile detection targets for metal ion fluorescent probes. Such probes with chalcogens serving as recognition sites can be classified into coordination- and reaction-type devices. Notably, thiols; sulfides; thiocarbonyls; S-containing crown ethers, aromatic hydrocarbons, and peptides; and Se/Te-containing ligands can all serve as detection sites for these probes. O/N-containing ligands for coordination, fluorophores, and linkers all affect the electron-donating ability and selectivity of the coordination system. In this review, we discuss ongoing research efforts in this area and propose some design strategies for introducing chalcogen elements into metal ion fluorescent probes by integrating Lewis acid–base theory and comparative studies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Technologies for lithium isotope separation based crown ether are reviewed. • Methods covered in this review include L-L extraction, S-L adsorption, chromatography. • Innovative technologies coupling crown ethers with others are summarized. • The advantages and challenges of these technologies are explained. • The directions for future research and development are identified. Nuclear energy is considered as the ultimate solution for future energy needs. High-purity lithium isotopes (6Li and 7Li) serve as the foundation raw materials for nuclear reactions. The development of environmentally friendly and efficient lithium isotope separation technologies plays an irreplaceable role in nuclear energy. Utilizing crown ethers for the selective complexation of metal ions has been proven to be a highly promising method for lithium isotope separation. In this review, various lithium isotope separation methods based on crown ether chemistry, including liquid–liquid extraction, solid–liquid adsorption, ion-exchange chromatography, membrane adsorption, and membrane chromatography techniques are introduced. The technologies coupling crown ethers with other separation methods, such as ionic liquid extraction and electric field migration, are summarized. The principles underlying lithium isotope separation are discussed from various perspectives. Finally, the current challenges and issues in lithium isotope separation research are described, and the future prospects for utilizing crown ethers in lithium isotope separation are outlined. To sum up, the review provides insights on crown ether chemistry and relative technologies for industrial-scale lithium isotopic enrichment in future nuclear energy research. [ABSTRACT FROM AUTHOR]

[Display omitted] • The free rotation of p-benzyl could make Cr6-Bz-DGA better match to REEs(III) of different ion radii with different binding mode. • The aza-crown ether of ligand provided 3 coordination atoms for smaller ionic radii Y(III)/Lu(III) and 6 atoms for larger ionic radii La(III). • The binding capacity of complexes with smaller ionic radii REEs(III) were stronger than complexes with larger ionic radii REEs(III) due to larger charge density. • The NMR titration experiment further proved M/L = 2:2 (aza-crown ether-REEs(III)-DGA connection) was the thermodynamic product. The development of new ligands is crucial for the functional application of REEs(III), because the coordination compounds of rare-earth elements (REEs) have many important applications in pharmaceuticals and nuclear medicine. In this paper, a novel ligand (Cr6-Bz-DGA) with the aza-crown ether and diglycolamide (DGA) units was designed to coordinate with light, medium, and heavy REEs(III). It was found that M/L = 2:2 species (aza-crown ether-REEs(III)-DGA connection) was the thermodynamically stable complex. The stability constants of Nd(III), Eu(III), and Ho(III) complexes were determined by UV–Vis and fluorescence titration, respectively, which were log β Nd = 7.49 ± 0.019, log β Eu = 7.10 ± 0.013 and log β Ho = 8.27 ± 0.032. The variation of fluorescence lifetime suggested that the Eu(III) ion was exclusively coordinated by the ligand with coordination number 9 in the inner sphere of the Eu(III) ion. The shifts of 1H NMR revealed that there are different coordination between the ligand and REEs(III). For larger ionic radii La(III), three O atoms of the DGA unit and five O and one N atoms of the aza-crown ether unit were supplied. While, for Y(III)/Lu(III) with smaller ion radii, the ligand supplied three O atoms from the DGA and one N atom and only two O atoms from the aza-crown ether. The displacement experiment of REEs(III) combined with ligand and the fitted stability constants prove that the smaller ionic radii REEs(III) more strongly bind with ligand than larger ionic radius REEs(III). These results may help understand the coordination behavior of REEs(III) and expand their potential applications. [ABSTRACT FROM AUTHOR]

A fascinating 18-crown-6-ether appended 25-oxasmaragdyrins (Cr-Prs) compound is investigated by doping alkali metal ions (Na+, K+), alkaline earth metal ions (Mg2+, Ca2+) and transition metal ions (Zn2+, Cd2+, Hg2+) to the crown ethers. Interestingly, the Hg2+@Cr-Prs compound exhibits a tremendous second-order nonlinear optical (NLO) property compared to other metal doping. Thus, the Cr-Prs can be used as efficient NLO-based metal ion detectors, and these results will broaden the scope and the efficiency of ion detection. [Display omitted] • Interestingly, the M n+@Cr-Prs undergo significant shrinkage of the crown ether, and the dihedral angle (Anglea) also changes after doping with metal ions. • Obviously, the natural population analysis (NPA) charge shows that the charge distribution of the compounds is regulated by the metal ions. • Significantly, the incorporation of metal ions, especially Hg2+ ion regulates and enhances effectively the first hyperpolarizabilities (β tot). • Moreover, the evolutions of unit sphere representation (USRs), the two-level model and the absorption spectra can well explain the tendency of β tot values. Crown ethers, known for their efficacy as metal ion traps, have garnered significant interest in optoelectronic applications due to their unique cavity structure and special binding ability with metals. Herein, we systematically designed and investigated the second-order nonlinear optical (NLO) properties of an intriguing compound, 18-crown-6 derivative appended with 25-oxasmaragdyrins (Cr-Prs), achieved through the incorporation of diverse metal ions into the crown ether ring. Significantly, the β tot values of compounds with alkaline earth metal ions (Mg2+, Ca2+) are greater than those compounds with alkali metal ions (Na+, K+). Interestingly, the Hg2+@Cr-Prs compound exhibits a tremendous second-order NLO property with the β tot value of 5.34 × 105 au. Further insights into substantial β tot values across all compounds were provided through a comprehensive analysis of the transition energies, the molecular orbitals, and the absorption spectra of the main excited states. The calculation results conclude that the second-order NLO properties of Cr-Prs can be modulated by incorporating metal ions into the crown ether ring. Crown ether emerges as a facilitator in detecting and identifying Hg2+ ions, serving as an effective NLO-based ion detector. These findings not only broaden the scope of cation detection and efficiency but also present innovative applications in analytical and optoelectronic research, encapsulating the essence of our study within a concise framework. [ABSTRACT FROM AUTHOR]

The article discusses a study on the enhancement and purification of pyrene emission in the solid state. Pyrene is a luminescent molecule that suffers from a decrease in fluorescence due to aggregation in the solid state. The researchers found that by encapsulating pyrene with a crown ether, the fluorescence can be significantly enhanced, resulting in a shift from aggregation-caused quenching to aggregation-induced emission. Additionally, the study also discovered a method to purify the impure emission of pyrene to a single emission. The full details of the study can be found in the Research Article by Q. Li and co-workers. [Extracted from the article]

• Artificial transmembrane ion channels based on supramolecular macrocycles have been successfully synthesized. • The channels with different chain lengths are constructed by the central acyclic cucurbituril and bilateral crown ethers. • The artificial transmembrane ion channels exhibit good transport efficiency for K+ and Na+ ions. • Artificial transmembrane ion channels with different chain lengths have varying effects on the transport of ions. Compared with natural channel proteins, artificial transmembrane channels based on macrocyclic molecules offer several advantages, including low price, stable properties, ease of structure modification, and functionalization. These benefits are highly significant for research purposes. Following this approach, a series of unimolecular ion channels have been designed and synthesized using crown ether and acyclic cucurbituril. The structure of the artificial channels was confirmed by NMR and HR-MS spectra. These unimolecular transmembrane channels have demonstrated effective efficiency in inserting into the lipid bilayers and transporting alkali metal cations, which can be substantiated through comprehensive fluorescence experimentation. Additionally, the alkali metal cation transport efficiency of the artificial channels is tunable by varying the length of the linkers between crown ether and acyclic cucurbituril. Thus, this study not only presented a simple and feasible unimolecular channel that could transport sodium and potassium selectively but also provided a simple model for constructing complex and controllable artificial transmembrane channels. [ABSTRACT FROM AUTHOR]

[Display omitted] • A colorimetric chemosensor for the detection of Cr(III) and Co(II) chloride in the presence of LMI was synthesized. • The acceptable LODs as 0.58 and 0.90 μM were validated in isopropanol for Cr(III) and Co(II), respectively. • A TLC test strip was successfully employed for the visible multication detection by L. • Dispersion of L in water was shown as a selective FL chemosensor of Cr(III). The present study describes the chemosensing capability of an N 2 O 4 -donor tetrabenzodiaza-crown ether macrocyclic ligand derivatized by two pyridine side arms to afford the flexible macrocyclic ligand, 5,20-bis(pyridin-4-ylmethyl)-5,6,12,13,19,20,26,27octahydrotetrabenzo [e,i,o,s][1,4,11,14]tetraoxa[7,18]diazacycloicosine (PMHBOA). A selective colorimetric behavior of PMHBOA for the prompt detection of Cr(ΙΙΙ) and Co(ΙΙ) can be observed with naked eyes. The 1H, 13C{H} NMR, and infrared spectroscopy disclosed the ligand binding capability for selective metal ions, ascribed to a 1:1 complex formation with Cr(III) and Co(II) cations in isopropanol. The limit of detection (LOD) values were calculated as 580 and 850 nM for Cr(ΙΙΙ) and Co(ΙΙ), respectively, accompanied with suitable LOQs as 1.95 µM for Cr(III) and 2.85 µM for Co(II), respectively. The reusability was confirmed in the presence of ethylenediaminetetraacetic acid (EDTA). Moreover, a TLC-based fabricated paper strip successfully applied PMHBOA as a chemosensor for synchronous visible detection of Cr(III) and Co(II) in their alcoholic solution. Meanwhile, the observed color change along with the turn-off fluorescent of PMHBOA guaranteed a felicitous choice of candidate for Cr(III) in the presence of other library metal ions in isopropanol:H 2 O (9/1 v/v) solution. A fast separation test on the filter paper, impregnated with PMHBOA, was also employed to separate Cr(III) and Co(II) cations from aqueous solutions by recording UV–vis spectra. The 1H NMR spectroscopy supported the macrocycle ring and side arms as the parallel coordination site of PMHBOA with Cr(III) and Co(II). [ABSTRACT FROM AUTHOR]

• Synthesis new perfluoro(phosphonic acid)s. • Grafting the side chains of a perfluoropolymer. • New perfluoro(phosphonic acid)s against hydroxyl radical degradations. • Vindicating the vulnerability of fluoroalkyl ether groups in Nafion from hydroxyl radical attacks. Nafion™ utilizes -SO 3 H groups for proton conduction. Using an alternative proton-exchange functionality like -PO 3 H 2 , -COOH, etc., to replace -SO 3 H in ion conductive fluoropolymers has attracted significant attention. For example, composite membranes comprising Nafion™ and perfluoro(carboxylic acid) bearing a -COOH group on its side chains have been used in color-alkali cells to reduce unwanted electrolyte crossovers. In the present paper, we reported a new synthetic strategy for constructing novel -PO 3 H 2 -bearing fluoropolymers (FBP). Our method employs a ZnI 2 -promoted phosphorylation reaction of triethyl phosphite that converts benzyl alcohol on a side chain of a fluoropolymer into a benzylphosphodiester group, followed by trimethylsilyl chloride (TMSCl) hydrolysis to yield FBP. This strategy has enabled us to graft a fluoropolymer side chain directly with phosphonic acid. Although the in-plane proton conductivities of FBP fluoropolymers are lower than those of Nafion™ 115, most FBPs, especially Homo-FBP that has no fluoroalkyl ether group on its side chains, are significantly more stable against hydroxyl radical degradations in Fenton tests. This paper presents a new method for the synthesis of -PO 3 H 2 -containing fluoropolymers and our work also confirms a novel strategy for enhancing the long-term stability of a proton-conductive fluoropolymer in electrical devices—eliminating or reducing fluoroalkyl ether groups on the side chains of the polymer. [Display omitted] [ABSTRACT FROM AUTHOR]

• Proposed a simpler scheme for preparing membranes using non-covalent interactions. • A composite membrane provides excellent rejection and large water permeability. • CE@GO membrane for highly selective removal by crown ether pore size effect. The highly efficient sieving of Cs+ from natural brine resources has garnered considerable attention for the extraction of cesium raw materials. However, for the trade-off between ion rejection and water permeability, it remains challenging for graphene oxide (GO) membranes to improve efficient sieving of Cs+ with a large water permeance. Here, we have successfully addressed this challenge by fabricating a GO membrane that incorporates crown ether (CE) through π-π and CH-π interactions with GO sheets. This CE intercalation has resulted in a significantly enhanced Cs+ sieving capability from salt lake brines, concurrently improving water permeance. The unique Cs+ selective cavity structure of the CE has enabled the GO membrane to exhibit a Cs+ rejection rate of 94.4 % and a water permeance of 15.8 L m−2 h−1 bar−1 at a Cs+ concentration of 0.150 mmol/L (∼20 ppm). Compared to the pure GO membrane, these results represent an improvement of over 70 % in Cs+ rejection and more than 230 % in water permeance. Interestingly, we have also observed that this GO membrane exhibits a low Na+ system consisting of two components, the separation factor of Cs+/Na+ reaches up to 5.0, which is significant in monovalent ionic membrane separations. These significant discoveries provide a promising strategy for the highly efficient extraction and concentration detection of Cs+ from complex ion solutions. [ABSTRACT FROM AUTHOR]