Search

The isomerization of azobenzo-13-crown ether can be expected to be hindered due to the polyoxyethylene linkage connecting the 2,2′-positions of azobenzene. The mixed reference spin-flip time-dependent density functional theory results reveal that the planar and rotational minima of the first photo-excited singlet state (S1) of the trans-isomer pass through a barrier (2.5–5.0 kcal/mol) as it goes toward the torsional conical intersection (S0/S1) geometry (

Perovskite solar cells have demonstrated exceptional development over the past decade, but their stability remains a challenge toward the application of this technology. Several strategies have been used to address this, and the use of host–guest complexation has recently attracted more interest. However, this approach has primarily been exploited in conventional perovskite solar cells based on n-i-p architectures, while its use in inverted p-i-n devices remains unexplored. Herein, we employ representative crown ether, dibenzo-24-crown-8, for interfacial host–guest complexation in inverted perovskite solar cells based on methylammonium and methylammonium-free formamidinium-cesium halide perovskite compositions. Upon post-treatment of the perovskite films, we observed nanostructures on the surface that were associated with the reduced amount of trap states at the interface with the electron transport layer. As a result, we demonstrate improved efficiencies and operational stabilities following ISOS-D-2I and ISOS-L-2I protocols, demonstrating the viability of this approach to advance device stability. [ABSTRACT FROM AUTHOR]

The aim of this review is to compile important results of single-crystal X-ray diffraction method, vibrational and NMR studies conducted on alkali metal ion complexes of some small ring benzo-crown ethers namely benzo-15-crown-5, dibenzo-15-crown-5 and benzo-12-crown-4 to determine their structure, stoichiometry and conformation in the solid-state. This review focuses on solid-state architectural diversity of alkali metal ion complexes studied by single-crystal X-ray diffraction method. Investigations of these complexes are significant as the interactions of alkali metal ions with these crown ethers mimic those present in nature between univalent ions and several bioligands. The benzo group in the macrocycle allows to monitor the complexation event by fluorescence studies and extends the applications of these crown ethers to fluorescent ion sensors. The selected small ring benzo oxa-crown ethers have cavities that match the size of the alkali metal ions and give stable complexes with them. The review presents results related to variation in infrared and Raman spectra of the ligands with changes in their crystal structure and conformation on complexation with alkali salts. Single-crystal X-ray diffraction studies of these complexes help to confirm the chemical structure, stoichiometry, stable conformation and presence of associated solvent molecules in the solid state. As noncovalent interactions are involved in the formation of these complexes, they are capable of forming supramolecular assemblies for building smart functional materials. [ABSTRACT FROM AUTHOR]

Hosts, a key component of inclusion complexes, are cyclic oligomeric compounds containing a cavity in which another component of the complex is bound by non-covalent forces. Chiral hosts are particularly important and interesting because they allow the study of specific intermolecular interactions and molecular recognition. The most important classes of chiral hosts and their physicochemical properties are briefly reviewed. An important part of this Review is the description of selected concepts necessary to understand the properties and behavior of inclusion complexes studied by the most suitable analytical method for studying inclusion complexes—nuclear magnetic resonance. [ABSTRACT FROM AUTHOR]

Metal ion detection is of paramount importance for health monitoring. The host should properly accommodate the desired ion and be selective with respect to other potential guests, which makes devising ion sensors a demanding task. Recently (Phys. Chem. Chem. Phys. 2023, 25, 32656), we suggested a procedure for a computational design of crown ethers that can capture magnesium ions. In the present contribution we apply the same approach to search for Mg2+ trap with thiophene units, in accord with proposed hosts for Na+ and K+ ions (Adv. Funct. Mater. 2016, 26, 514). Additionally, we present a procedure based on the combination of Density Functional Theory based Molecular Dynamics and the Interacting Quantum Fragments methodology for determination of host–guest interaction and binding energies in a model with a large number of explicit solvent molecules. The presented strategy could be applied for identification of the right host for an arbitrary guest. [ABSTRACT FROM AUTHOR]

Iron‐porphyrin systems are among the best catalysts to reduce selectively CO2 to CO. Electronic modification of the porphyrin skeleton by substituents can enhance the catalytic efficiency of the complexes. In this work, we modified the iron porphyrin complex with crown‐ether auxiliaries and tested the effect of complexation with alkali metals on their electrocatalytic properties for CO2 reduction. The presence of Na+ or K+ resulted in a positive shift of the onset potential by 210 mV while not compromising the catalytic current. This effect was maintained after the immobilization at the vulcanized carbon support, and the catalyst showed the Faradaic efficiency above 90 % for CO2 to CO reduction in aqueous solution of NaHCO3 or KHCO3 in a wide range of overpotentials. Hence, host‐guest chemistry at the periphery of the CO2 reduction catalysts can tune the electronic properties of the catalysts and thereby increase the catalytic efficiency. [ABSTRACT FROM AUTHOR]

Crownphyrinogens and crownphyrins constitute a group of macrocycles that combine the structural facets of porphyrinoids and crown ethers. The dual‐nature cavity embedded in their molecules enables reactivity involving two structurally distinct parts of the macrocyclic ligand. Upon Ni(II) and Pd(II) insertion, coordination compounds are produced wherein the metal is incorporated into the porphyrinoid‐like pocket, resulting in monomeric or accordion‐like dimeric products, depending on the oxidation level of the macrocycle and metal cation. The reactions with Na(I) and K(I) resulted in the formation of complexes where only the crown ether segment of the molecule is involved in metal binding, yielding remarkable dimeric species. The exploitation of a crownphyrin large enough to accommodate two metal cations allowed the synthesis of an alkali/transition metal binuclear complexes wherein the macrocycle demonstrated the Janus reactivity with one cavity acting as a porphyrinoid and the other mimicking the crown ether. [ABSTRACT FROM AUTHOR]

The formation of barium sulfate scale is a persistent and formidable challenge across various industrial processes. In order to effectively mitigate this problem, this study proposed the development of an innovative azacrown ether-based macrocycle descaling agent. Using density functional theory, an in-depth analysis of the surface energy of different barium sulfate crystal facets was carried out, together with a detailed investigation into the adsorption properties of the functional groups on the (001) surface. A further comprehensive investigation was carried out to determine how changes in the nitrogen and oxygen atoms in the crown ether framework influence its adsorption affinity to barium ions. In addition, a detailed analysis was carried out to elucidate the molecular interactions between crown ethers with pyridine carboxylic acid side chains and barium sulfate. The newly developed decalcifying macrocycle descaling agent exhibited superior adsorption performance, achieving an adsorption energy for barium ions approximately −4.1512 ev higher than that of conventional DTPA decalcifiers. This remarkable improvement is mainly attributed to the pivotal role of electrostatic forces in the coordination process between the macrocycle descaling agent and barium ions, with an electrostatic potential value reaching −143.37 kcal/mol. This discovery not only introduces a novel approach to the removal of barium sulfate scale but also highlights the significant potential of macrocycle chemistry in industrial applications. [ABSTRACT FROM AUTHOR]

Thorium is a weak radioactive element, but the control of its concentration in natural aqueous systems is of great interest for health, because it is a toxic heavy metal. The present paper presents the recovery of thorium from diluted synthetic aqueous systems by nanofiltration. The membranes used for the nanofiltration of systems containing thorium species are composites containing 4′-Aminobenzo-15-crown-5 ether (ABCE) and sulfonated poly–etherether–ketone (sPEEK). The composite membranes (ABCE–sPEEK) were characterized by scanning electron microscopy (SEM), energy-dispersive X–Ray spectroscopy (EDAX), thermal analysis (TG and DSC), and from the perspective of thorium removal performance. To determine the process performance, the variables were the following: the nature of the composite membrane, the concentration of thorium in the aqueous systems, the rotation speed of the stirrer, and the pressure and the pH of the thorium aqueous system. When using pure water, a permeate flux value of 12 L·m−2 h−1 was obtained for the sPEEK membrane, and a permeate flux value of up to 15 L·m−2 h−1 was obtained for the ABCE–sPEEK composite membrane. The use of mechanical stirring, with a propeller stirrer, lead to an increase in the permeate flux value of pure water by about 20% for each of the studied membranes. Depending on the concentration of thorium and the pH of the feed solution, retentions between 84.9% and 98.4% were obtained. An important observation was the retention jump at pH 2 for the ABCE–sPEEK composite membrane. In the paper, a thorium ion retention mechanism is proposed for the sPEEK membrane and the ABCE–sPEEK composite membrane. [ABSTRACT FROM AUTHOR]

The active template synthesis of mechanically interlocked molecular architectures exploits the dual ability of various structural elements (metals or, in the case of metal-free active template synthesis, particular arrangements of functional groups) to serve as both a template for the organisation of building blocks and as a catalyst to facilitate the formation of covalent bonds between them. This enables the entwined or threaded intermediate structure to be covalently captured under kinetic control. Unlike classical passive template synthesis, the intercomponent interactions transiently used to promote the assembly typically do not 'live on' in the interlocked product, meaning that active template synthesis can be traceless and used for constructing mechanically interlocked molecules that do not feature strong binding interactions between the components. Since its introduction in 2006, active template synthesis has been used to prepare a variety of rotaxanes, catenanes and knots. Amongst the metal–ion-mediated versions of the strategy, the copper(I)-catalysed alkyne–azide cycloaddition (CuAAC) remains the most extensively used transformation, although a broad range of other catalytic reactions and transition metals also provide effective manifolds. In metal-free active template synthesis, the recent discovery of the acceleration of the reaction of primary amines with electrophiles through the cavity of crown ethers has proved effective for forming an array of rotaxanes without recognition elements, including compact rotaxane superbases, dissipatively assembled rotaxanes and molecular pumps. This Review details the active template concept, outlines its advantages and limitations for the synthesis of interlocked molecules, and charts the diverse set of reactions that have been used with this strategy to date. The application of active template synthesis in various domains is discussed, including molecular machinery, mechanical chirality, catalysis, molecular recognition and various aspects of materials science. [ABSTRACT FROM AUTHOR]

Recently, research on polyoxometalates (POMs) has gained significant momentum. Owing to their properties as electronic sponges, POMs catalyst harbor substantial potential in lithium‐sulfur battery research. However, POMs undergo a transformation into reduced heteropoly blue (HPB) during electrochemical reactions, which then dissolve into the electrolyte, resulting in catalyst loss. In this research, we amalgamated 18‐crown‐6 (CR6) with K3PW12O40, (KPW), synthesized a novel POM‐based supramolecular compound, and integrated it with graphene oxide (GO) to fabricate a multi‐functional composite polypropylene (PP) separator KPW‐CR6/GO/PP. The crown ether array was employed to immobilize POM and construct ion transport channels, thereby enhancing the Li+ migration rate and capturing polysulfides. Subsequently, leveraging the stable structure and redox properties of POM, the polysulfide is catalyzed to transform and inhibit the shuttle effect, thereby protecting the Li anode. The lithium‐sulfur batteries with the Crown ether‐POM supramolecular compound separators, exhibit enhanced capacity and stability (1073.3 mAh g−1 at 1.0 C, and 81.5 % retention rate after 250 cycles). The battery (S loading: 3.2 mg cm−2) presents an initial specific discharge capacity of 543.4 mAh g−1 at 0.5 C, with 89.8 % of the capacity retained after 160 cycles. This underlines the practical application potential of Crown ether‐POM supramolecular materials in Li−S batteries. [ABSTRACT FROM AUTHOR]

Improving the slow redox kinetics of sulfur species and shuttling issues of soluble intermediates induced from the multiphase sulfur redox reactions are crucial factors for developing the next‐generation high‐energy‐density lithium‐sulfur (Li−S) batteries. In this study, we successfully constructed a novel molecular electrocatalyst through in situ polymerization of bis(3,4‐dibromobenzene)‐18‐crown‐6 (BD18C6) with polysulfide anions on the cathode interface. The crown ether (CE)‐based polymer acts as a spatial "fence" to precisely control the unique redox characteristics of sulfur species, which could confine sulfur substance within its interior and interact with lithium polysulfides (LiPSs) to optimize the reaction barrier of sulfur species. The "fence" structure and the double‐sided Li+ penetrability of the CE molecule may also prevent the CE catalytic sites from being covered by sulfur during cycling. This new fence‐type electrocatalyst mitigates the "shuttle effect", enhances the redox activity of sulfur species, and promotes the formation of three‐dimensional stacked lithium sulfide (Li2S) simultaneously. It thus enables lithium‐sulfur batteries to exhibit superior rate performance and cycle stability, which may also inspire development facing analogous multiphase electrochemical energy‐efficient conversion process. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. The contents list includes various articles on topics such as halogen bonding in crown ether chemistry, metal-organic framework-derived materials for enhanced performance of aqueous zinc ion batteries, and the effect of grain boundary doping on the mechanical behavior of Ta bicrystal. The journal is published by The Royal Society of Chemistry, a leading chemistry community. [Extracted from the article]

The role of the C–I⋯O halogen bonding in crown ether chemistry has been analyzed and rationalized by using thirteen newly synthesized cocrystals as models. The monotopic C–I⋯O halogen bonding was found to play a dominant role, whereas the bifurcated halogen bonding and the hydrogen-bond enhanced halogen bonding play minor roles. An unexpected new finding is that some binary mixtures of halogen-bond donor and acceptor can spontaneously absorb trace amounts of water from the solvent during the crystal growth period, forming more complex ternary cocrystals. [ABSTRACT FROM AUTHOR]

Capillary electrochromatography (CEC) is a rapidly emerging separation technique that merges the high separation efficiency of capillary electrophoresis with the exceptional selectivity of liquid chromatography. However, it remains a synthetic challenge to design functional chiral stationary phases (CSPs) with high chemical stability against acid and base in CEC enantioseparation. Here we demonstrate that incorporating chiral crown ethers into stable covalent organic frameworks (COFs) enables efficient and stable separations of racemates by CEC. This facilitates the crafting of two three-dimensional (3D) chiral COFs by polycondensation of a chiral 1,1'-binaphyl-20-crown-6-derived dialdehyde and tetraamines with diisopropyl substituents. Both feature an 11-fold interpenetrated diamond framework, characterized by tubular open channels decorated with chiral crown ethers serving as enantioselective recognition and binding sites. These frameworks demonstrate excellent stability in water, acid and base, thanks to the presence of bulky isopropyl groups that shield the dynamic imine linkages. Moreover, the precisely defined COF channels enhanced the accessibility of the enclosed crown ethers to the analytes while providing strong protection against harsh environments, rendering them suitable for CSPs in CEC separations. They can effectively separate some important enantiomers, including ketones, epoxides and alkaline substances, when utilized as coatings on chiral columns, particularly facilitating the chiral separation of drugs. This study advances the application of COFs in electrochromatographic separations, expanding the scope of porous materials design and engineering to create COFs with targeted enantioselective properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • Efficient dual-adsorption of MO and Cd(II) using biogenic fibrous silica. • Crown ether ionic liquid functionalization enhances pollutant interaction with the adsorbent. • Sustainable adsorbent derived from sorghum waste prepared by an eco-friendly synthesis. • Adsorption processes confirmed as spontaneous and highly efficient. • High surface area and pore volume of the adsorbent provide abundant active sites. In pursuit of sustainable nanomaterial production, this study presents a novel biogenic fibrous silica sphere functionalized with a crown ether ionic liquid for advanced dual-adsorption of methyl orange and Cd(II) from aqueous solution. Sorghum waste serves as the silica source in the adsorbent preparation process, ensuring an eco-friendly approach. The benzo-15-crown-5 ionic liquid is coupled to thiol-functionalized fibrous silica spheres through an efficient thiol-ene click reaction. Under constant conditions (temperature: 298 K, solution volume = 50 mL, adsorbent dosage = 5 mg, pH = 7, shaking speed = 200 rpm), the synthesized material demonstrates maximum adsorption capacities of 507.1 mg g−1 and 306.3 mg g−1 for methyl orange and Cd(II), respectively, according to the Langmuir model. Thermodynamic investigations reveal exothermic adsorption for methyl orange with an enthalpy change of −77.49 KJ mol−1, while endothermic adsorption is observed for Cd(II) with an enthalpy of +24.10 KJ mol−1. The entropy change of adsorption is −0.153 KJ mol−1 K−1 for methyl orange, indicating a more ordered state, and + 0.192 KJ mol−1 K−1 for Cd(II), suggesting increased disorder. The change in Gibbs free energy ranges from −32.66 to −29.60 KJ mol−1 for methyl orange and −32.29 to −35.99 KJ mol−1 for Cd(II), demonstrating that both adsorption processes are spontaneous. These results indicate that the adsorbent has potential as a dual-adsorption material for water remediation applications. [ABSTRACT FROM AUTHOR]

The aqueous interface-rich system has been proposed to act as a trigger and a reservoir for reactive radicals, playing a crucial role in chemical reactions. Although much is known about the redox reactivity of water microdroplets at "droplets-in-gas" interfaces, it remains poorly understood for "bubbles-in-water" interfaces that are created by feeding gas through the porous membrane of the gas diffusion electrode. Here we reveal the spontaneous generation of highly reactive redox radical species detected by using electron paramagnetic resonance under such conditions without applying any bias and loading any catalysts. In combination with ultraviolet-visible spectroscopy, the redox feature has been further verified through several probe molecules. Unexpectedly, introducing crown ether allows to isolate and stabilize both water radical cations and hydrated electrons thus substantially increasing redox reactivity. Our finding suggests a reactive microenvironment at the interface of the gas diffusion electrode owing to the coexistence of oxidative and reductive species. The gas diffusion electrode interface can boost chemical reactions, yet its microenvironment properties are largely unexplored. Here, the authors report the spontaneous generation of reactive redox radical species at the interface using Janus hydrophobic/hydrophilic porous carbon papers to feed gas. [ABSTRACT FROM AUTHOR]

Styrylpyridinium dye bearing azadithia‐15‐crown‐5 ether receptor group SP and 4‐alkoxy‐1,8‐naphthalimide fluorophore were linked using copper‐catalyzed azide‐alkyne cycloaddition click reaction to afford dyad compound NI‐SP. Chemosensor NI‐SP exhibited selective ratiometric fluorescent response to the presence of Hg2+ in aqueous solution due to the interplay between resonance energy transfer (RET) and intramolecular charge transfer (ICT) processes occurred upon excitation. The observed switching of the ratio of emission intensities in the blue and red channels R was higher than in the case of monochromophoric styrylpyridine derivative SP showing ratiometric response based on ICT mechanism only. Biological studies revealed that NI‐SP penetrates into human lung adenocarcinoma A549 cells and accumulates in cytoplasm and lysosomes. When cells were pre‐incubated with mercury (II) perchlorate, the ratio R was increased 2.6 times, which enables detection of intracellular Hg2+ ions and their quantitative analysis in the 0.7–6.0 μM concentration range. [ABSTRACT FROM AUTHOR]

Crown ether‐assisted supramolecular assembly is a robust strategy for manipulating low‐dimensional metal halides. In this study, the supramolecular assembly of 0D‐Cs3Cu2I5 is presented. Upon the addition of 15‐crown‐5 (15C5) to Cs3Cu2I5, 15C5 immediately coordinates with Cs+ to form the cone‐shaped [(15C5)Cs]+. Simultaneously, one of the iodine atoms is removed from the [Cu2I5]3‐ cluster, resulting in the formation of a sub‐planar rhombic [Cu2I4]2− unit. This process leads to white emission, specifically [(15C5)Cs]2[Cu2I4], which exhibits a photoluminescence quantum yield (PLQY) close to unity. The [(15C5)Cs]+ further reacts with 15C5 to form the sandwich‐type cationic structure [(15C5)2Cs]+, accompanied by the generation of red emission [(15C5)2Cs]2[Cu2I4]. By carefully controlling the amount of 15C5, various emission composites can be achieved, particularly tunable white emission. The assembly process is reversible. The pristine Cs3Cu2I5 can be recovered after thermal curing because of the volatility of crown ether and the weak Cs‐crown ether bond. Theoretical calculations have demonstrated that the coordination of the crown ether primarily affects the energy level, leading to changes in the excited state and photophysical properties. The applications in anticounterfeiting and LED phosphors have been demonstrated. This work provides a new approach for the development of low‐dimensional copper halides with promising applications in optoelectronics. [ABSTRACT FROM AUTHOR]

We describe the synthesis and characterization of a [2]rotaxane comprising a dibenzo‐24‐crown‐8 (DB24C8) macrocyclic component and a thread containing three recognition sites: ammonium (AmH+), bipyridinium (Bpy2+) and triazolium (Trz+). AmH+ and Bpy2+ are responsive to fully orthogonal stimuli, pH and electrochemical, which allows to precisely control the directional translation of the macrocycle along the axle. A better understanding of the processes driving the operation of the system was obtained thanks to an in‐depth thermodynamic characterization. Orthogonal stimuli responsive tristable rotaxanes represent the starting point for the creation of linear motors and the development of molecular logic gates. [ABSTRACT FROM AUTHOR]

A six‐cyclic crown ether‐type pillar[5]arene was synthesized, and the five ethylene oxide loops were located outside the cavity and not affected by temperature changes which was confirmed by variable‐temperature NMR experiment in DMSO‐d6 and CDCl3 and 2D 1H−1H NOESY experiment in CDCl3. The six‐cyclic pillar[5]‐crown also showed greater binding ability of host‐guest with bis(pyridinium) derivatives than conventional alkoxy pillar[5]arenes that illustrated through 1H NMR titration spectroscopic experiment in acetone‐d6/CDCl3 (1 : 1) and UV‐vis titration experiments in CHCl3 at room temperature. The five benzocrown ethers at the periphery were able to bind metal cations by 1H NMR titration spectroscopic experiment in CD2Cl2/methanol‐d4(9 : 1). [ABSTRACT FROM AUTHOR]

Two sets of co-formers, polyfluorinated arylenediamines with variable structural elements and macrocyclic ethers of different sizes, were used to study the patterns of self-assembly of co-crystals and to rank the intermolecular interactions. The co-crystallization stoichiometry was found to increase from 1 : 1 to 2 : 1 in the series trifluoro-1,3-phenylenediamine, 2,4-diaminotrifluoropyridine, and 2,4-diaminotrifluoronitrobenzene and with decreasing crown ether size due to restructuring of guest--host interactions and forming guest-guest interactions. 18-Crown-6 and 15-crown-5 ethers form the typical N--H...Ocr H-bonds connecting two Ocr atoms with one bifunctional proton donor NH2; when going to 12-crown-4, two Ocr atoms become connected with the Hamino atoms of two arylenediamine molecules. Modes of guest--guest bonding and supramolecular motifs in 2 : 1 co-crystals are determined by HB acceptors and p + π systems in arylenediamine: o-N--H...Nhet and p-N--H...F interactions form face-to-face dimers united in a chain; p-N-H...Onitro and o-N--H...Onitro contacts generate head-to-tail and head-to-side chains; π...π and X...π (X = F, O, N) electron interactions form off-set stacks. Quantum chemical calculations reveal an increase of the packing enthalpies and bonding energies with increasing arylenediamine electron affinity and crown ether size. According to MEP, BCP and NCI analyses, these effects are caused either by strengthening of the interactions due to a greater electrostatic contribution, or by multiplying bonding contacts. Quantifying the interactions allowed us to identify the key supramolecular synthons and related elements of the co-former structure, which can serve as tools in the molecular crystal design. [ABSTRACT FROM AUTHOR]

Supramolecular adhesives are attracting considerable attentions owing to their dynamic and reversible bonding, while the complex curing conditions and poor performance under extreme conditions severely restrict their applicability. Herein, a series of tetra‐crown ether‐terminated polyethylene glycol (TCE‐PEG) adhesives are presented in which plenty of supramolecular interactions, including Van der Waals, hydrogen bonding, π–π staking, metal coordination, and electrostatic ones, provide strong adhesion on multiple types of substrates. Highly relevant for practical applications, ultra‐strong adhesivity of TCE‐PEG can be achieved without requiring additional ultraviolet radiation, heat, or chemical treatment at ambient temperature. It also exhibits durable adhesive behavior, excellent underwater stability, and low‐temperature tolerance. Especially, by incorporating ionic polymer fragments of polyethyleneimine hydrochloride, additional hydrogen bonding between secondary amines and crown ether rings can be induced to enhance the lap‐shear strength to 7.21 MPa due to the formation of supramolecular cross‐linked network. This work pioneers a rather unique supramolecular approach for easily formed, ultra‐strong crown‐ether‐based adhesives bearing great potential for applications in critical environments of limited heat source and unallowed solvent usage. [ABSTRACT FROM AUTHOR]

Crown ethers (CEs), known for their exceptional host–guest complexation, offer potential as linkers in covalent organic frameworks (COFs) for enhanced performance in catalysis and host–guest binding. However, their highly flexible conformation and low symmetry limit the diversity of CE‐derived COFs. Here, we introduce a novel C3‐symmetrical azacrown ether (ACE) building block, tris(pyrido)[18]crown‐6 (TPy18C6), for COF fabrication (ACE‐COF‐1 and ACE‐COF‐2) via reticular synthesis. This approach enables precise integration of CEs into COFs, enhancing Ni2+ ion immobilization while maintaining crystallinity. The resulting Ni2+‐doped COFs (Ni@ACE‐COF‐1 and Ni@ACE‐COF‐2) exhibit high discharge capacity (up to 1.27 mAh ⋅ cm−2 at 8 mA ⋅ cm−2) and exceptional cycling stability (>1000 cycles) as cathode materials in aqueous alkaline nickel‐zinc batteries. This study serves as an exemplar of the seamless integration of macrocyclic chemistry and reticular chemistry, laying the groundwork for extending the macrocyclic‐synthon driven strategy to a diverse array of COF building blocks, ultimately yielding advanced materials tailored for specific applications. [ABSTRACT FROM AUTHOR]

This study investigates the structural and phase transition characteristics of supramolecular complexes composed of 18-crown-6 ether and hydrogen selenate (HSeO4−) anions with various cations (K+, Rb+, Cs+). Single crystals of [18-crown-6·K]HSeO4·2H2O, [18-crown-6·Rb]HSeO4·H2O, [18-crown-6·Cs]HSeO4·H2O, [18-crown-6·K]HSeO4, and [18-crown-6·K](HSeO4)0.5(HSO4)0.5 were grown and their structures determined via single-crystal X-ray diffraction. Differential scanning calorimetry and variable-temperature powder X-ray diffraction were employed to analyse dehydration and phase transition behaviors. The inclusion of 18-crown-6 ether significantly lowered the superprotonic phase transition temperatures by approximately 40 °C compared to pure solid acids. Additionally, substituting HSO4− with HSeO4− decreased phase transition temperatures for K and Cs-complexes and modified the phase transition behavior of the Rb-complex from two-step to single-step isostructural phase transition. Attempts to form solid solutions between the HSeO4− and HSO4− complexes yielded mixed results, with notable success in modulating phase transition temperatures in K-complexes. [ABSTRACT FROM AUTHOR]

[Display omitted] Polyaniline (PANI) has been widely used as a cathode in aqueous zinc-ion batteries (AZIBs) because of its attractive conductivity and energy storage capability. However, the extensive application of PANI is limited by spontaneous deprotonation and slow diffusion kinetics. Herein, an 18-crown-6-functionalised PANI pseudorotaxane (18C6@PANI) cathode is successfully developed through a facile template-directed polymerisation reaction. The 18C6@PANI cathode exhibits a high specific capacity of 256 mAh g−1 at 0.2 A/g, excellent rate performance of 134 mAh g−1 at 6 A/g and outstanding cycle stability at a high current density of 3 A/g over 10,000 cycles. Experimental and theoretical analyses demonstrate the formation of the –N–Zn–O– structure. The abundant supramolecular channels in pseudorotaxane, induced by crown ether functional groups, are beneficial for achieving superior cyclability and rate capability. These encouraging results highlight the potential for designing more efficient PANI-based cathodes for high-performance AZIBs. [ABSTRACT FROM AUTHOR]

The challenge of efficiently extracting Li+ from brines with high Na+ or Mg2+ concentrations has led to extensive research on developing highly selective separation membranes for electrodialysis. Various studies have demonstrated that nanofiltration membranes or adsorbents modified with crown ethers (CEs) such as 2-OH-12-crown-4-ether (12CE), 2-OH-18-crown-6-ether (18CE), and 2-OH-15-crown-5-ether (15CE) show selectivity for Li+ in brines. This study aims to develop high-performance cation exchange membranes (CEMs) using CEs to enhance Li+ selectivity and to compare the performance of various CE-modified membranes for selective electrodialysis. The novel CEM (CR671) was modified with 12CE, 18CE, and 15CE to identify the optimal CE for efficient Li+ recovery during brine electrodialysis. The modification process included polydopamine (PDA) treatment and the deposition of polyethyleneimine (PEI) complexes with the different CEs via hydrogen bonding. Interfacial polymerization with 1,3,5-benzenetricarbonyl trichloride-crosslinked PEI was used to create specific channels for Li+ transport within the modified membranes (12CE/CR671, 15CE/CR671, and 18CE/CR671). The successful application of CE coatings and Li+ selectivity of the modified membranes were verified through Fourier-transform infrared spectroscopy, zeta-potential measurements, and electrochemical impedance spectroscopy. Bench-scale electrodialysis tests showed significant improvements in permselectivity and Li+ flux for all three modified membranes. In brines with high Na+ and Mg2+ concentrations, the 15CE/CR671 membrane demonstrated more significant improvements in permselectivity compared to the 12CE/CR671 (3.3-fold and 1.7-fold) and the 18CE/CR671 (2.4-fold and 2.6-fold) membranes at current densities of 2.3 mA/cm2 and 2.2 mA/cm2, respectively. At higher current densities of 14.7 mA/cm2 in Mg2+-rich brine and 15.9 mA/cm2 in Na+-rich brine, the 15CE/CR671 membrane showed greater improvements in Li+ flux, approximately 2.1-fold and 2.3-fold, and 3.2-fold and 3.4-fold compared to the 12CE/CR671 and 18CE/CR671 membranes. This study underscores the superior performance of 15CE-modified membranes for efficient Li+ recovery with low energy demand and offers valuable insights for advancing electrodialysis processes in challenging brine environments. [ABSTRACT FROM AUTHOR]

The effect of crown ethers and polyglycols on the liquid-phase oxidation of cyclohexane and alkylaromatic hydrocarbons (toluene and p-xylene) with molecular oxygen catalyzed by transition metal salts has been investigated. It has been determined that crown ethers increase the reaction rate at both low and high conversion levels of cyclohexane and alkylaromatic hydrocarbons. The additives under study primarily affect the selectivity of the oxidation products. Crown ether and polyglycol additives to cobalt naphthenate increase the cyclohexanone to cyclohexanol molar ratio in cyclohexane oxidation. The crown ether additives to cobalt acetate increase the selectivity for alcohol in the initial stage of toluene and p-xylene oxidation. At higher alkylarene conversion, the additives enhance the selectivity for carboxylic acids. We assume that crown ethers and polyglycols form complexes with transition metal ions, changing the redox potential of the ions. This change in redox potential affects both the reaction rate and the selectivity of the oxidation products. The study concludes that crown ether and polyglycol additives influence the stages of the catalytic liquid-phase oxidation of hydrocarbons. [ABSTRACT FROM AUTHOR]

Nature performs critical physiological functions using a series of structurally and functionally diverse membrane proteins embedded in cell membranes, in which native ion protein channels modify the electrical potential inside and outside the cell membrane through charged ion movements. Consequently, the cell responds to external stimuli, playing an essential role in various life activities, such as nerve excitation conduction, neurotransmitter release, muscle movement, and control of cell differentiation. Supramolecular artificial channels, which mimic native protein channels in structure and function, adopt unimolecular or self‐assembled structures, such as crown ethers, cyclodextrins, cucurbiturils, column arenes, cyclic peptide nanotubes, and metal‐organic artificial channels, in channel construction strategies. Owing to the various driving forces involved, artificial synthetic ion channels can be divided into artificial cation and anion channels in terms of ion selectivity. Cation selectivity usually originates from ion coordination, whereas anion selectivity is related to hydrogen bonding, ion pairing, and anion‐dipole interactions. Several studies have been conducted on artificial cation channels, and several reviews have summarized them in detail; however, the research on anions is still in the initial stages, and related reviews have rarely been reported. Hence, this article primarily focuses on the recent research on anion channels. [ABSTRACT FROM AUTHOR]

The document is the contents list for an issue of the journal Chemical Communications. It includes the titles and authors of various articles and features that will be included in the issue. The articles cover a range of topics in the field of chemistry, including recent advances in biosensing systems, continuous flow synthesis, electrochemical construction, and more. The journal is published by The Royal Society of Chemistry, a leading chemistry community. [Extracted from the article]

In this communication, we designed a highly selective camphor sulfonyl functionalized crown-ether-tethered calix[4]arene-derived organocatalyst for asymmetric Strecker reaction to provide the desired cyano adducts in high yields (∼99.9% yield) and enantioselectivities (up to 99.3% ee). Furthermore, 2 step facile syntheses of the antiplatelet drug (S)-clopidogrel exemplify the potential of this method for the preparation of commercial compounds. [ABSTRACT FROM AUTHOR]

Understanding how subtle structural differences between macrocyclic conformational isomers impact their properties and separation has garnered increasing attention in the field of supramolecular synthetic chemistry. In this work, a series of tetraphenylene (TPE)-embedded butterfly bis-crown ether macrocycles (BCE[n], n = 4–7), comprising two crown ether side rings and a TPE core, are synthesized through intramolecular McMurry coupling. Unexpectedly, the presence of flexible oligoethylene chains with varying lengths are found to influence molecular conformation via multiple intramolecular interactions, resulting in the formation of two stabilized conformers with specific semi-rigid symmetric/asymmetric structures (sym-BCE[n] and asym-BCE[n], n = 5, 6). Moreover, it is noteworthy that neither symmetric nor asymmetric conformers are present in the more rigid BCE[4] or the more flexible BCE[7]. Interestingly, these conformers display distinct fluorescence properties and host-guest binding abilities, and only sym-BCE[5] can serve as a host for chiral polymer binding, resulting in the formation of chiral supramolecular assemblies through host-guest interaction induced chirality. Moreover, both circular dichroism and circularly polarized luminescence signals of the obtained assemblies can be switched off by the addition of sodium ion, suggesting potential applications in the field of dynamic chiral materials. Understanding how structural differences impact the properties of macrocyclic conformational isomers has garnered attention in the field of supramolecular chemistry. Here, the authors synthesize tetraphenylene-embedded butterfly bis-crown ether macrocycles with conformers that display distinct fluorescence properties and host-guest binding abilities. [ABSTRACT FROM AUTHOR]

Efficient delivery of therapeutic agents to the lesion site or specific cells is an important way to achieve "toxicity reduction and efficacy enhancement". Macrocycles have always provided many novel ideas for drug or gene loading and delivery processes. Specifically, macrocycles represented by crown ethers, cyclodextrins, cucurbit[n]urils, calix[n]arenes, and pillar[n]arenes have unique properties, which are different cavity structures, good biocompatibility, and good stability. Benefited from these diverse properties, a variety of supramolecular drug delivery systems can be designed and constructed to effectively improve the physical and chemical properties of guest molecules as needed. This review provides an outlook on the current application status and main limitations of macrocycles in supramolecular drug delivery systems. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis and sensing characteristics of 4,4′‐methoxy‐substituted BODIPY fluorescent probes (O‐BODIPYs) 3, 4 and 5 equipped with differently sized benzo‐crown ethers (cf. Scheme 1, 3 (benzo‐15‐crown‐5), 4 (benzo‐18‐crown‐6) and 5 (benzo‐21‐crown7)). O‐BODIPYs 3, 4 and 5 exhibited in comparison to their known F‐BODIPY analogues 3a, 4a and 5a (cf. Scheme 1) an improved solubility in aqueous medium and higher fluorescence quantum yields. Fluorometric study in aqueous solutions of 3, 4 and 5 in the presence of different cations show cation induced fluorescence enhancements (FE). Compared to the benzo‐crown ether substituted F‐BODIPY analogues 3a, 4a and 5a, we found for the free O‐BODIPYs 3, 4 and 5 higher fluorescence quantum yields (φf) but lower cation induced FEs. We show that in aqueous medium the fluorescence quenching process (OFF switching), a photoinduced electron transfer, in O‐BODIPYs 3, 4 and 5 is less effective and consequently sensitive and selective ON switching of the fluorescence by cations, too. Albeit these observations the novel benzo‐21‐crown‐7 equipped fluorescent probe 5 exhibits a good fluorometric Ba2+ selectivity and Ba2+ sensitivity in conjunction to their aqueous solubility. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis and sensing characteristics of 4,4′‐methoxy‐substituted BODIPY fluorescent probes (O‐BODIPYs) 3, 4 and 5 equipped with differently sized benzo‐crown ethers (cf. Scheme 1, 3 (benzo‐15‐crown‐5), 4 (benzo‐18‐crown‐6) and 5 (benzo‐21‐crown7)). O‐BODIPYs 3, 4 and 5 exhibited in comparison to their known F‐BODIPY analogues 3a, 4a and 5a (cf. Scheme 1) an improved solubility in aqueous medium and higher fluorescence quantum yields. Fluorometric study in aqueous solutions of 3, 4 and 5 in the presence of different cations show cation induced fluorescence enhancements (FE). Compared to the benzo‐crown ether substituted F‐BODIPY analogues 3a, 4a and 5a, we found for the free O‐BODIPYs 3, 4 and 5 higher fluorescence quantum yields (φf) but lower cation induced FEs. We show that in aqueous medium the fluorescence quenching process (OFF switching), a photoinduced electron transfer, in O‐BODIPYs 3, 4 and 5 is less effective and consequently sensitive and selective ON switching of the fluorescence by cations, too. Albeit these observations the novel benzo‐21‐crown‐7 equipped fluorescent probe 5 exhibits a good fluorometric Ba2+ selectivity and Ba2+ sensitivity in conjunction to their aqueous solubility. [ABSTRACT FROM AUTHOR]

1H NMR titration of 18-crown-6 with diphenyliodonium triflate and dibenziodolium triflate indicated that the acyclic iodine(III)-containing species has a higher binding constant value compared with the cyclic analogue. Formation of triple associates diphenyliodonium⋯18-crown-6⋯diphenyliodonium was observed in CD3CN. DFT calculations and QTAIM analysis indicated that the acyclic iodonium salt forms a higher number of interactions with the crown ether compared with the cyclic cation, which results in the formation of triple associates. The formation of dibenziodolium⋯18-crown-6⋯dibenziodolium triple associates turned out to be energetically unfavorable, which agrees with the experimentally obtained data. [ABSTRACT FROM AUTHOR]

The thermal stability of dibenzo-21-crown-7 (DB21C7) and its solution in 1,2-dichloroethane (DCE) after contact with nitrogen dioxide, which is a product of nitric acid degradation, was studied. It is shown that exothermic processes accompanied by the release of gaseous products are observed in inert and oxidizing atmosphere. The compounds formed after contact with nitrogen dioxide were determined by gas chromatography–mass spectrometry. Differences in gaseous products in the temperature range of 300℃ were defined for the initial crown ether and for DB21С7 and its solution in DСE after contact with NO2. [ABSTRACT FROM AUTHOR]

Dynamic control of the motion in a catenane remains a big challenge as it requires precise design and sophisticated well‐organized structures. This paper reports the design and synthesis of a donor‐acceptor [2]catenane through mechanical interlocking, employing a crown ether featuring two dibenzylammonium salts on its side arms as the host and a cyclobis(paraquat‐p‐phenylene) (CBPQT ⋅ 4PF6) ring as the guest molecule. By addition of external acid or base, the catenane can form self‐complexed or decomplexed compounds to alter the cavity size of the crown ether ring, consequently affecting circumrotation rate of CBPQT ⋅ 4PF6 ring of the catenane. This study offers insights for the design and exploration of artificial molecular machines with intricate cascading responsive mechanisms. [ABSTRACT FROM AUTHOR]

In this study, three supramolecular compounds, namely [Na(18-crown-6)]ReO4 (1), [K(18-crown-6)]ReO4 (2) and [NH4(15-crown-5)2]ReO4 (3) were synthesized and characterized using microanalysis, thermogravimetric, differential scanning calorimetric and powder X-ray diffraction techniques, among others. Herein, 15-crown-5 and 18-crown-6 represent 1,4,7,10,13-pentaoxacyclopentadecane and 1,4,7,10,13,16-hexaoxacyclooctadecane, respectively. Both 1 and 2 experienced one-step reversible phase transition at ∼436 K and ∼360 K, respectively, while 3 underwent three steps of reversible phase transitions at ∼289 K, ∼352 K and ∼380 K. A dielectric anomaly occurred at ∼433 K (∼363 K) for 1 (2), consistent with the temperature obtained from DSC measurement. In the dielectric spectra of 3, anomalies were observed at ∼386 K and ∼433 K, corresponding to two thermal anomalies observed at higher temperatures in the DSC plot. However, there was an absence of dielectric response around 289 K where a thermal anomaly appeared in the DSC plot. The distinct crystal structures, phase transitions and dielectric properties in 1–3 stem from the degree of compatibility between the radii of M+ (Na+, K+ and NH4+) and the ring sizes of crown ethers (18-crown-6 and 15-crown-5). [ABSTRACT FROM AUTHOR]

This study utilizes single‐crystal X‐ray diffraction in a diamond anvil cell (DAC) to explore the structural response of [Cs(18‐Crown‐6)][SbCl6] under high pressure (HP). Notably, the pressure drives large Cs atoms closer to the center of the crown ether cavity, ultimately requiring pressures of 3 GPa for its complete encapsulation. Remarkably, the absence of short contacts in the crystal classifies the material as a "loose crystal" offering a unique model for understanding compression mechanisms. The crystal exhibits highly anisotropic compression behavior with an impressive volume reduction and non‐linear pressure – unit‐cell parameters relationships facilitated by the absence of short CH⋅⋅⋅Cl contacts up to 0.9 GPa. Beyond this pressure, steric repulsion due to shortening H⋅⋅⋅Cl and H⋅⋅⋅H interactions hinders further effective compression, so pressure dependence on unit cell parameters and volume becomes more linear. The behavior of [Cs(18‐Crown‐6)][SbCl6] at different conditions was studied using Raman spectroscopy and supplemented by DFT calculations. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) as one of the promising alternatives to lithium-ion batteries have achieved remarkable progress in the past. However, the all-climate performance is still very challenging for SIBs. Herein, 15-Crown-5 (15-C-5) is screened as an electrolyte additive from a number of ether molecules theoretically. The good sodiophilicity, high molecule rigidity, and bulky size enable it to reshape the solvation sheath and promote the anion engagement in the solvated structures by molecule crowding. This change also enhances Na-ion transfer, inhibits side reactions, and leads to a thin and robust solid-electrolyte interphase. Furthermore, the electrochemical stability and operating temperature windows of the electrolyte are extended. These profits improve the electrochemical performance of SIBs in all climates, much better than the case without 15-C-5. This improvement is also adopted to μ-Sn, μ-Bi, hard carbon, and MoS2. This work opens a door to prioritize the potential molecules in theory for advanced electrolytes. [ABSTRACT FROM AUTHOR]

In the design of dynamic supramolecular systems used in molecular machines, it is important to understand the binding preferences between the macrocycle and stations along the thread. Here, we apply 1H NMR spectroscopy to investigate the relative stabilities of a series of linear alkylammonium templated pseudorotaxanes with the general formula [H2NRR'][Cr7CoF8(O2CCH2tBu)16] by exchanging the cation in solution. Our results show that the pseudorotaxanes are able to exchange threads via a dissociative mechanism. The position of equilibrium is dependent upon the ammonium cation and solvent used. Short chain primary ammonium cations are shown to be far less favourable macrocycle stations than secondary ammonium cations. Collision‐induced dissociation mass spectrometry (CID‐MS) has been used to look at disassembly of the pseudorotaxanes in a solvent‐free environment and stability trends compared to those in acetone‐d6. The energy needed to induce 50 % of the precursor ion loss (E50) is used and shows a similar trend to the equilibria measured by NMR. The relative stabilities of these hybrid inorganic‐organic pseudo‐rotaxanes are different to those of host‐guest compounds involving crown ethers and this may be valuable for the design of molecular machines. [ABSTRACT FROM AUTHOR]

The solid–liquid phase transfer catalyzed (S-L PTC) properties of polyethylene glycol (PEG) were investigated in the preparation of dialkyl disulfide (R2S2) by oxidative coupling of alkyl mercaptan and sulfur with K2CO3 as catalyst under atmospheric pressure and solvent-free conditions. The results have showed that the S-L PTC properties of PEG are not significantly different from those of crown ether. The S-L PTC properties of PEG are reduced due to methylation of the terminal hydroxyl groups, indicating that the terminal hydroxyl group in PEG plays an important role in stabilizing the [PEG-K2+ CO32−] complex. The results of infrared spectral analysis confirm that CO32− in K2CO3 has a strong interaction with the terminal hydroxyl group in PEG. At the fixed molar ratio of –CH2CH2O-/K2CO3, the increase of PEG chain length has a positive correlation with the S-L PTC performance. The reaction rate and yield of R2S2 can be improved by increasing the amount of K2CO3 and the molar ratio of -CH2CH2O-/K2CO3 appropriately. The PEG400/K2CO3 system exhibits very high catalytic activity for the oxidative coupling reaction of alkyl mercaptan with sulfur as oxidant. The yield of the reaction product (n-C8H17)2S2 can still reach more than 97% by using 0.1 mol% K2CO3 and 0.006 mol% PEG400 (based on sulfur). [ABSTRACT FROM AUTHOR]

Lithium‐oxygen batteries possess an extremely high theoretical energy density, rendering them a prime candidate for next‐generation secondary batteries. However, they still face multiple problems such as huge charge polarization and poor life, which lay a significant gap between laboratory research and commercial applications. In this work, we adopt 15‐crown‐5 ether (C15) as solvent to regulate the generation of discharge products in lithium‐oxygen batteries. The coronal structure endows C15 with strong affinity to Li+, firmly stabilizes the intermediate LiO2 and discharge product Li2O2. Thus, the crystalline Li2O2 is amorphized into easily decomposable amorphous products. The lithium‐oxygen batteries assembled with 0.5 M C15 electrolyte show an increased discharge capacity from 4.0 mAh cm−2 to 5.7 mAh cm−2 and a low charge overpotential of 0.88 V during the whole lifespan at 0.05 mA cm−2. The batteries with 1 M C15 electrolyte can cycle stably for 140 cycles. Furthermore, the amorphous characteristic of Li2O2 product is preserved when matched with redox mediators such as LiI, with the charge polarization further decreasing to 0.74 V over a cycle life of 190 cycles. This provides new possibilities for electrolyte design to promote Li2O2 amorphization and reduce charge overpotential in lithium‐oxygen batteries. [ABSTRACT FROM AUTHOR]

A novel porous and magnetic nanoparticle, composed of Fe3O4/MCM‐41 functionalized with a kryptofix‐21 crown ether, has been successfully synthesized. This was achieved through the treatment of 3‐chloropropyl functionalized Fe3O4/MCM‐41 with the crown ether, followed by the grafting of Cu (II) onto the material, resulting in the formation of Fe3O4/MCM‐41/kryptofix‐21/Cu. The material's 2D‐hexagonally ordered mesophases were analyzed using small‐angle‐PXRD and TEM‐imaging. The Cu (II)‐anchored porous material, Fe3O4/MCM‐41/kryptofix‐21/Cu, exhibited remarkable catalytic activity in the Click reaction between azides and phenylacetylene, conducted in ethylene glycol/water at a temperature of 70 °C. This reaction led to the synthesis of a diverse range of 1,4‐disubstituted 1,2,3‐triazoles. The catalyst demonstrated excellent recyclability, maintaining its catalytic activity for up to eight cycles without any significant loss. Furthermore, no significant leaching of Cu was observed, highlighting the potential of this magnetically innovative nanoporous catalyst in the regioselective formation of 1,4‐disubstituted 1,2,3‐triazolic compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] New derivatives of dithiaazacrown ethers containing ψ-arylpyridine subunits were prepared based on the Hantzsch synthesis. The obtained compounds showed potential activities toward Hep-G2 cancer cell line, in both in silico and in vitro studies. The compounds were also good ligands for complex chemistry with metal ions due to possessing up to four heteroatoms and relatively big size of the crown ring. [ABSTRACT FROM AUTHOR]

90Sr is one of the most monitored fission products. New efficient methods for strontium separation are therefore sought. Over the past 20 years, crown ethers solutions in ionic liquids (ILs) have been confirmed to efficiently extract strontium from acidic solutions. Despite all the work done in this field, the extraction mechanism is still not completely clear. Depending on experimental conditions, the extraction is believed to proceed either in the form of an ion-association complex [Sr·CE·(NO3)2] or via exchange between [Sr·CE]2+ and two IL cations. This work aims to study the influence of several extraction parameters and compare them with the presumed mechanisms. [ABSTRACT FROM AUTHOR]

Copyright of Nachrichten aus der Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Di-tert-butyldiphosphatetrahedrane (tBuCP)2 (A) is a reactive tetrahedral molecule which may serve as a source of new phosphaorganic molecules and ligands. However, the redox chemistry of this compound has not yet been investigated. Here, we show that the reduction of A with alkali metals (AM = Li, Na, K, Rb and Cs) affords 1,2,3-triphospholides [AM(crown ether)][1,2,3-P3C2tBu2] (1–5, [AM(crown ether)] = [Li([12]crown-4)2]+, [Na([15]crown-5)2]+, [K([18]crown-6)]+, [Rb([18]crown-6)]+, and Cs+) with 1,3-diphospholides [AM(crown ether)][1,3-P2C3tBu3] (6–10) formed as by-products. The potassium salt 3 was isolated on a preparative scale, allowing for reactivity studies. Transmetalation with iron(II) and ruthenium(II) chlorides yielded the sandwich complexes [Cp*M(η5-1,2,3-P3C2tBu2)] (11, M = Fe; 12, M = Ru, Cp* = C5Me5) featuring η5-coordinated triphospholide ligands. Treatment of 3 with [Cp2Fe][BAr4F] or [H(Et2O)2BAr4F] (BAr4F = B{C6H3(CF3)2}4) afforded the polyphosphorus compound tBu4C4P6 (13), which presumably results from the dimerisation of a 1,2,3-triphospholyl radical intermediate (1,2,3-P3C2tBu2)˙ (3˙). Tetracyclic 13 is closely structurally related to an isomer of the hydrocarbon hypostrophene (C10H10). [ABSTRACT FROM AUTHOR]

We developed a new approach for the synthesis of flavanone from chalcones without electrical energy, such as stirring or heating, by using a cesium fluoride–crown ether complex. This "zero electrical energy reaction" is a new category of reaction that has the potential to replace the general organic reaction. [ABSTRACT FROM AUTHOR]