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Conformational regulation among two or more distant sites is not only one of the main pathways to accomplish multiple tasks in complex biological systems but also represents a powerful strategy to obtain stimuli-responsive supramolecular nanoconstructs with tailored physicochemical performance. We herein report the fabrication of a photochromic supramolecular assembly, which can be synergistically activated by the conformational regulation with bis(4,8-disulfonato-1,5-naphtho)-32-crown-8 and then reversibly switched by the through-space communication between restricted stilbazolium salt and photochromic dithienylethene. This work demonstrates that the synergistic conformational modulation via intra- and intermolecular interactions can be developed as a generalizable approach to construct more advanced biomimetic nanomaterials.

A new tetraphenylethylene-cyclodextrin (TPE-CD) conjugate with a linkage composed of long triethylene glycol chain and triazole ring on the CD rim has been designed and synthesized. The TPE-CD conjugate exists in a stretched form in DMSO and enhances its fluorescence after addition of a small amount of water due to aggregation-induced emission (AIE) effect. However, in the presence of a large amount of water, the TPE unit will enter the cyclodextrin cavity to form a folded self-inclusion compound. In the self-inclusion compound, not only nitrogen-containing pseudo-crown ether is formed but also arouses photo-induced electron transfer (PET) process from nitrogen atoms of triazole ring to TPE unit and quenches the fluorescence although more aggregation occurs in more water. This is the first finding that TPE-macrocycle conjugate can form pseudo-crown ether and has both the AIE phenomenon and the PET effect. Interestingly, only mercury ion arouses the fluorescence recover of the self-inclusion compound by entering the pseudo-crown ether cavity and blocking the PET process by binding to the nitrogen atoms, while other tested metal ions almost have no effect on the fluorescence. Therefore, the TPE-CD conjugate can be used for the highly selective fluorescence "Turn-On" detection of Hg2+.

Constitutionally adaptive chemistry of selenium-containing crown ethers (CEs) offers a new platform for controlling/switching the hydration of bolaamphiphile skeletons in water in an effective and simple manner by the virtue of covalent bonding. The adaptive behaviour of the macrocyclic bolaamphiphiles (transformations between C7SeBola and C7SeOBola) in response to redox environment was found to be a decisive factor.

Natural transport channels (or carriers), such as aquaporins, are a distinct type of biomacromolecule capable of highly effective transmembrane transport of water or ions. Such behavior is routine for biology but has proved difficult to achieve in synthetic systems. Perhaps most significantly, the enantioselective transmembrane transport of biomolecules is an especially challenging problem both for chemists and for natural systems. Herein, a group of homochiral zirconium metal-organic cages with four triangular opening windows have been proposed as artificial biomolecular channels for enantioselective transmembrane transport of natural amino acids. These structurally well-defined coordination cages are assembled from six synthetically accessible BINOL-derived chiral ligands as spacers and four n-Bu3-Cp3Zr3 clusters as vertices, forming tetrahedral-shaped architectures that feature an intrinsically chiral cavity decorated with an array of specifically positioned binding sites mediated from phenol to phenyl ether to crown ether groups. Fascinatingly, the transformation of single-molecule chirality to global supramolecular chirality within the space-restricted chiral microenvironments accompanies unprecedented chiral amplification, leading to the enantiospecific recognition of amino acids. By virtue of the highly structural stability and excellent biocompatibility, the orientation-independent cages can be molecularly embedded into lipid membranes, biomimetically serving as single-molecular chiral channels for polar-residue amino acids, with the properties that cage-1 featuring hydroxyl groups preferentially transports the l-asparagine, whereas cage-2 attaching crown ether groups spontaneously favor transporting d-arginine. We therefore develop a new type of self-assembled system that can potentially mimic the functions of transmembrane proteins in nature, which is a realistic candidate for further biomedical applications.

Multiresponsive materials can adapt to numerous changes in their local environment, which makes them highly valuable for various applications. Although nanostructured and polymeric multiresponsive materials are plentiful, small-molecule analogues are scarce. This work presents a compact cyclometalated platinum(II) complex that bears a crown ether cavity (18C6-PtII); the intimate ring/emitter connectivity is key to unlocking multiresponsiveness. Complex 18C6-PtII responds to (i) cationic guests, producing changes in luminescence in both solution and the solid state, (ii) solvent molecules, which perturb the packing of the complex in the solid state and cause reversible color changes, and (iii) solvent polarity, which leads to controlled aggregation. These responses may enable 18C6-PtII to function as a sensor for ions and solvents, or as a functional unit for the fabrication of hybrid supramolecular polymers and metallogels.

ConspectusAsymmetric cation-binding catalysis in principle enables the use of (alkali) metal salts, otherwise insoluble in organic solvents, as reagents and effectors in enantioselective reactions. However, this concept has been a formidable challenge due to the difficulties associated with creating a highly organized chiral environment for cations and anions simultaneously. Over the last four decades, various chiral crown ethers have been developed as cation-binding phase-transfer catalysts and examined in asymmetric catalysis. However, the limited ability of chiral crown ethers to generate soluble reactive anions in a confined chiral cage offers a restricted reaction scope and unsatisfactory chirality induction. To address the constraints of monofunctional chiral crown ethers as cation-binding catalysts, it is therefore desirable to develop a cooperative cation-binding catalyst possessing secondary binding sites for anions, which enables the generation of a reactive anion within a chiral cage of a catalyst. This account summarizes our design, development, and applications of chiral BINOL-based oligoethylene glycols (oligoEGs) as a new type of bifunctional cation-binding catalyst. We initially found that achiral oligoEGs were efficient promoters in nucleophilic fluorination with potassium fluoride. Thereby, we hypothesized that, by breaking the closed cyclic ether unit of chiral crown ethers, the free terminal -OH groups could activate the electrophiles by hydrogen bonding whereas the ether oxygens could act as the Lewis base to coordinate metal ions, thus generating soluble anions in a confined chiral cage. This hypothesis was realized by synthesizing a series of chiral variants of oligoEGs by connecting two 3,3'-disubstituted-BINOL units with glycol linkers. Readily available BINOL-based chiral oligoEGs enabled numerous asymmetric transformations out of the reach of chiral monofunctional crown ether catalysts. We have demonstrated that this new type of bifunctional cation-binding catalysts can generate a soluble fluoride anion from alkali metal fluorides, which can be a versatile chiral promoter for diverse asymmetric catalytic reactions, kinetic resolution (selectivity factor of up to ∼2300), asymmetric protonation, Mannich reactions, tandem cyclization reactions, and the isomerization of allylic alcohols and hemithioacetals. We have also successfully utilized our chiral oligoEG catalysts along with alkali metal salts of carbon- and heteroatom-based nucleophiles, respectively, for asymmetric Strecker reactions and the asymmetric synthesis of chiral aminals. The power of our cooperative cation-binding catalysis was exemplified by kinetic resolution reactions of secondary alcohols, achieving highly enantioselective catalysis with only

It is usually believed that the binding affinity and selectivity of an alkali metal ion with crown ether are defined by the size matching model. However, the underlying mechanism of the specific host-guest interactions and the structural dynamics of the metal ions confined in the cavity of the crown ethers in the solutions are still not clear. In this report, a series of alkali thiocyanate salts (XSCN; X = Li, Na, K, and Cs) complexed with 18-crown-6 (a typical crown ether) in the chloroform solutions were studied by the polarization-selective infrared pump-probe spectroscopy and the ultrafast two-dimensional infrared (2D IR) spectroscopy. The SCN- counteranions were employed as the local vibrational probe to reveal the specific host-guest interactions in the crown ether complexes. The rotational dynamics and spectral diffusion of SCN- vibration were both measured by ultrafast IR spectroscopy, and it was found that the metal cations hosted by the crown ethers can have a pronounced effect on the rotational dynamics of the counteranions. The reorientational time constants of the SCN- vibration in the complexation follow the order Li+ > Na+ > K+ ≃ Cs+. More importantly, the spectral diffusion dynamics of SCN-, which quantifies the decay of the correlation of the frequency fluctuations in the complexation, was also affected by the metal ions but showed a different order of cationic effect. A detailed analysis of the 2D IR data showed that the spectral diffusion of SCN- counteranion clearly decayed with two different time scales in the complex of 18-crown-6 with K+. The 3-4-fold slowdown in spectral diffusion indicated that the fluctuation of SCN- vibrational transition frequency was strongly affected by the K+ cation due to the geometric constraint imposed by the crown ether. The results should help the researchers to unravel the specific host-guest interactions and further reveal the origination of the binding selectivity of crown ether for metal cations in the condensed phases from the perspective of structural dynamics.

Divalent mercury (Hg2+) is highly toxic in nature and extensively found in different natural water bodies worldwide. Thus, rapid trace-level monitoring of Hg2+, as well as its effective removal fro...

The properties of metal/dioxygen species, which are key intermediates in oxidation catalysis, can be modulated by interaction with redox-inactive Lewis acids, but structural information about these adducts is scarce. Here we demonstrate that even mildly Lewis acidic alkali metal ions, which are typically viewed as innocent "spectators", bind strongly to a reactive cis-peroxo dicopper(II) intermediate. Unprecedented structural insight has now been obtained from X-ray crystallographic characterization of the "bare" CuII2(μ-η1:η1-O2) motif and its Li+, Na+, and K+ complexes. UV-vis, Raman, and electrochemical studies show that the binding persists in MeCN solution, growing stronger in proportion to the cation's Lewis acidity. The affinity for Li+ is surprisingly high (∼70 × 104 M-1), leading to Li+ extraction from its crown ether complex. Computational analysis indicates that the alkali ions influence the entire Cu-OO-Cu core, modulating the degree of charge transfer from copper to dioxygen. This induces significant changes in the electronic, magnetic, and electrochemical signatures of the Cu2O2 species. These findings have far-reaching implications for analyses of transient metal/dioxygen intermediates, which are often studied in situ, and they may be relevant to many (bio)chemical oxidation processes when considering the widespread presence of alkali cations in synthetic and natural environments.

In recent years, the global emergence of antibacterial resistance has led to the development of new antibacterial drugs with unique chemical structures. The FDA has recently approved delafloxacin for acute bacterial infection treatment. The proposed potentiometric sensor is considered as the first electrochemical method for accurate, precise, and sensitive determination of delafloxacin. It was based on developing a novel polymeric material that functioned as a recognition element and a transducer at the same time. This polymeric material was fabricated by the covalent polymerization of aniline monomers with the crown ether ionophore and followed by the ionic attachment to the surface of the MWCNTs. A linear response ranging from 1 × 10–3 to 1 × 10–8 mol L−1 and a high sensitivity reached nano-molar level down to 3.5 × 10–9 mol L−1 have been displayed by the fabricated sensor. It was used efficiently in human plasma, pure form, and pharmaceutical tablets for the quantitation of delafloxacin with high recovery ranged from 97.68% to 100.45% and without any extraction or pretreatment steps. The proposed sensor is characterized by high selectivity and stability over 143 days with no surface renewal.

The synthesized S-enantiomer of the crown ether was used as an adsorbent to separate the racemic mixture of L-alanine ether of phenamine into individual diastereomers by column chromatography. Chromatographic separation occurred due to the formation of complexes of different stability between diastereomers and optically selective adsorbents on a host-guest principle. The separated diastereomers were converted into enantiomers by hydrolysis. The structure and optical activity of the synthesized crown ether and separated enantiomers were investigated by physicochemical methods

Low level radioactive liquid waste (LLW) obtained after treatment of Intermediate level radioactive waste (ILW) is highly alkaline and rich in 99Tc as the pertechnetate ion. It is considered as a long-term hazard in nuclear waste disposal. Solvent extraction of Pertechnetate species was performed using crown ether impregnated hollow fibre membrane using nitrobenzene and TBP solvents in different membrane modules. Better D values were obtained with Nitrobenzene however in view of toxicity of nitrobenzene study was also conducted with TBP and TBP nitrobenzene mix solvent. With nitrobenzene solvent almost 95% of 99Tc was separated in four contacts. However with increase in TBP content the percentage extraction is decreasing due to decrease in D value. The results are presented and discussed in the paper.

[2]Catenane, [2]rotaxane, and [2]pseudorotaxane based on a cyclic titanium oxide cluster, [Ti8O8(SO4)16]16- (Ti8), and cyclic/linear alkylammonium cations are reported. Their syntheses, structures, spectroscopy, and stability in water were studied. These molecules were synthesized from and remained intact upon redissolution in acidic water. Hence, the cluster Ti8 is a promising metal oxide ring that can be used as an inorganic analogue of crown ether to assemble inorganic-organic hybrid mechanical interlocked supramolecular assemblies in water.

Mechanically interlocked molecules (MIMs) with discrete molecular components linked through a mechanical bond in space can be harnessed for the operation of molecular switches and machines, which shows huge potential to imitate the dynamic response of natural enzymes. In this work, rotaxane compounds were adopted as building monomers for the synthesis of a crown-ether ring mechanically intercalated covalence organic framework (COF). This incorporation of MIMs into open architecture implemented large amplitude motions, whose wheel slid along the axle in response to external stimulation. After impregnation with Zn2+ ions, the relative locations of two zinc active sites (crown-ether coordinated Zn(II) and bipyridine coordinated Zn(II)) are endowed with great flexibility to fit the conformational transformation of an organophosphorus agent during the hydrolytic process. Notably, the resulting self-adaptive binuclear zinc center in a crown-ether-threaded COF network is endowed with a record catalytic ability, with a rate over 85.5 μM min–1 for organophosphorus degradation. The strategy of synthesis for porous artificial enzymes through the introduction of mechanically bound crown ether will enable significant breakthroughs and new synthetic concepts for the development of advanced biomimetic catalysts., Based on a flexible pocket, natural enzymes with conformational dynamics corresponding to the important transition-state barrier crossing steps enable the unparalleled catalytic rate and selectivity.

Highly strained cyclic xanthene dimers, which serve as models for reduced graphene oxide (RGO), were synthesized by Ni(0) mediated homo-coupling reactions. The dimers are obtained as highly stable ...

Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) havebeen computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.

Supramolecular assemblies based on oligo(ethylene glycol) (OEG) building blocks are well-known for their neutral chemical property and thermal-responsive behavior. Here, the cyclic "CLOSED" and linear "OPEN" typologies of OEGs led to dramatic difference in the sensitivity to guanidinium-containing species. From thermodynamic studies, the association constant (Ka) between the "CLOSED" form amphiphile and guanidinium salt was determined to be 28.7 M-1, whereas there was no detectable binding affinity for the "OPEN" form. Therefore, considering ion specificity, the present results establish that crown ether derivatives with "CLOSED" and "OPEN" topologies provide an easy-to-access model pair with designed ion-recognition sites and special functional moieties and geometries (like the binding pockets of enzymes or ion channels in cellular members) that allow the manipulation of the intercrossed relationship between supramolecular solutes, waters, and guanidinium salts. These supramolecular forces in aqueous solution offered an alternative strategy to fabricate thermal-responsive systems in ionic medium.

The reaction of the vanadium(III) tris(silylamide) V{N(SiMe3)2}3 with LiAlH4 in diethyl ether gives the highly unstable mixed-metal polyhydride [V(μ2-H)6[Al{N(SiMe3)2}2]3][Li(OEt2)3] (1), which was structurally characterized. Alternatively, performing the same reaction in the presence of 12-crown-4 affords a rare example of a structurally verified vanadium terminal hydride complex, [VH{N(SiMe3)2}3][Li(12-crown-4)2] (2). The corresponding deuteride 2D was also prepared using LiAlD4. In contrast, no hydride complexes were isolated by reaction of M{N(SiMe3)2}3 (M = Cr, Fe) with LiAlH4 and 12-crown-4. Instead, these reactions afforded the anionic metal(II) complexes [M{N(SiMe3)2}3][Li(12-crown-4)2] (3, M = Cr; 4, M = Fe). The reaction of the iron(III) tris(silylamide) Fe{N(SiMe3)2}3 with lithium aluminum hydride without a crown ether gives the "hydrido inverse crown" complex [Fe(μ2-H){N(SiMe3)2}2(μ2-Li)]2 (5), while treatment of the same trisamide with alane trimethylamine complex gives the iron(II) polyhydride complex Fe(μ2-H)6[Al{N(SiMe3)2}2]2[Al{N(SiMe3)2}(NMe3)] (6). Complexes 2-6 were characterized by X-ray crystallography, as well as by infrared, electronic, and 1H and 13C (complex 6) NMR spectroscopies. Complexes 1 and 6 are apparently formed by an unusual "metallo-transamination" process.

The gas-phase structure of 18-crown-6 in the presence of Li+ and Na+ cations is highly flexible and generally distorted. Using density functional theory calculations, natural bond orbital analysis, and symmetry measures, we reveal the driving forces behind the structural and energy trends of 18-crown-6 and its phenyl substituents. We show that the structural deviation from C3-symmetry increases with the non-bonded interactions between the occupied spx orbitals of the crowns' oxygen atoms and the unoccupied 2s orbital of the cation. These orbital interactions are strongly correlated with the overall host-guest interaction energy. Our approach highlights the role of non-bonded interactions and paves the way for deeper understanding of structure-reactivity relations of flexible host-guest systems.

A number of polydentate diazoarylcelluloses have been proposed in the form of reagent indicator, in which the functional diazo group is connected to the rest of the molecule through fragments of crown ether. When azo coupling of diazoaryl celluloses with amino and hydroxy aryl compounds having an azo coupling active in the molecule, a coordination cavity was formed, the denticity of which was increased due to donor atoms of the formed azo group and the adjacent ortho substituent from the azo component. This led to the formation of polydentate chelants, few differing in color, but in the presence of one or another metal ion—to the formation of their complexes, significantly differing from each other in color characteristics and electronic absorption and diffuse reflection spectra. Examples of selective chromogenic reactions of diazoarylcelluloses with 2-naphthol with the participation of gold(III) in a mixture of structurally similar substances and with 2,4-xylidine with the participation of cobalt(II) in a mixture of 6 isomeric xylidines are given.

All biological pumps are autonomous catalysts; they maintain the out-of-equilibrium conditions of the cell by harnessing the energy released from their catalytic decomposition of a chemical fuel1–3. A number of artificial molecular pumps have been reported to date4, but they are all either fuelled by light5–10 or require repetitive sequential additions of reagents or varying of an electric potential during each cycle to operate11–16. Here we describe an autonomous chemically fuelled information ratchet17–20 that in the presence of fuel continuously pumps crown ether macrocycles from bulk solution onto a molecular axle without the need for further intervention. The mechanism uses the position of a crown ether on an axle both to promote barrier attachment behind it upon threading and to suppress subsequent barrier removal until the ring has migrated to a catchment region. Tuning the dynamics of both processes20,21 enables the molecular machine22–25 to pump macrocycles continuously from their lowest energy state in bulk solution to a higher energy state on the axle. The ratchet action is experimentally demonstrated by the progressive pumping of up to three macrocycles onto the axle from bulk solution under conditions where barrier formation and removal occur continuously. The out-of-equilibrium [n]rotaxanes (characterized with n up to 4) are maintained for as long as unreacted fuel is present, after which the rings slowly de-thread. The use of catalysis to drive artificial molecular pumps opens up new opportunities, insights and research directions at the interface of catalysis and molecular machinery. A molecular-scale pump whose operation is driven by a catalytic process when in the presence of chemical fuel is autonomous, within an operating window, as long as the fuel lasts.

The hierarchical self-assembly (HSA) strategy widely utilized in biological systems has been applied in artificial systems to orchestrate small building blocks into complex functional architectures. The non-interfering interactions glue various building blocks together and produce new species with attractive properties. Herein, we functionalized NHC-based assemblies with orthogonal host-guest interaction to fabricate metal-carbene based supramolecular polymer gel. A series of unique crown ether-appended cylinder-like trinuclear AuI hexacarbene assemblies [Au3(L)2](PF6)3 (L=D1–D4, A1–A4) were synthesized from the corresponding trisimidazolium salts H3-L(PF6)3 (L=D1–D4, A1–A4) in which the N-wingtip of the imidazole moieties were substituted with three identical crown ether groups of different sizes (B15C5, B18C6, B21C7, DB24C8). The gold carbene assembly is able to complex six ammonium salts without disrupting the underlying metal-carbene cylinders. In addition, the supramolecular polymer metallogel featuring a multiple-responsiveness can be formed by using [Au3(A4)2](PF6)3 appended with DB24C8 as the core and bisammonium salt as the cross-linker. The case of introducing orthogonal interaction to NHC moiety by N-wingtip substitution demonstrates the feasibility and the power of such strategy to expand the NHC-based supramolecular system and endow them with novel properties.

Crown ethers containing an acridone or an acridine unit are successfully applied opto- and electrochemical cation sensors. The heteroaromatic unit of these macrocycles can be in different forms during the applications, which have a strong influence on the sensing behavior. Moreover, in the case of acridono-macrocycles a prototropic equilibrium takes place upon complexation, which is effected by the physicochemical characteristics. A Pb2+-selective acridono-18-crown-6 ether and its 9-phenylacridino-analogue were used as model compounds for comparing the different forms of the heterocyclic units of these sensor molecules. Since in most practical sensor applications of the fluorescent hosts a non-neutral aqueous medium is present, studies on complexation and signaling were carried out from the aspect of the relationship among protonation, coordinating ability, complex stability and tautomeric equilibrium. A strong interdependence among these factors was found and limitations of using unsubstituted acridino- and acridono-sensor molecules in comparison with their 9-substituted-acridino-analogues were discussed. This study will hopefully serve as a useful standpoint for future development of ionophore-based sensors containing an acridone or an acridine unit.

Density functional theory calculations were applied to understand the selectivity between Am3+ and Eu3+ ions with the crown ethers type ligands. 18C6 is predicted to form the most stable complex with Eu3+ and show the higher stability for Am3+ over Eu3+, being consistent with previously reported Am3+/Eu3+ selectivity. We modeled N- and S-donor complexes by using framework of 18C6 complex and analyzed the complexation Gibbs energies, indicating that 18C6 with N-donor atoms is suitable for both complexation and higher Am3+ stability over Eu3+ due to the stronger covalent interaction.

A novel diselenide-containing crown ether (BC7Se2) was fabricated, which can polymerize to form cyclic oligomers through intermolecular dynamic covalent reaction by irradiation of visible light. The size and distribution of oligomers are related to the monomer concentration. The decomposition reaction of oligomers is controlled by topology and solvents. Furthermore, potassium cation can inhibit the polymerization of BC7Se2 and accelerate the decomposition of oligomers.

We report the synthesis, single-crystal structure, solid-state ultraviolet-visible-near-infrared spectroscopy, and theoretical calculations on the first trivalent plutonium crown ether inclusion complex, [(H3O)(18-crown-6)][Pu(H2O)4(18-crown-6)](ClO4)4·2(H2O) (denoted as PuIII-18C6). Single-crystal X-ray diffraction reveals that PuIII-18C6 crystallizes in the orthorhombic space group of Pccn, which is assembled by independent ionic pairs including [Pu(H2O)4(18-crown-6)]3+, [(H3O)(18-crown-6)]+, and perchlorate anions. The plutonium atom is fully encapsulated within the cavity of the 18-crown-6, generating a distorted bicapped square antiprism geometry. The theoretical evaluation confirms that weak Pu-O dative bond is involved between PuIII ions with 18-crown-6. This work may deepen the understanding of the host-guest interactions between trivalent transuranic and macrocyclic ligands.