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The dynamic interplay of coordination bonds within metal‐organic cages offers a unique avenue for structural evolution in response to external stimuli, presenting a promising strategy for the construction of chiral assemblies. This adaptability is crucial for the selective synthesis of homochiral assemblies and advancement of asymmetric catalysis. In this study, we report the self‐assembly of an achiral square‐planar Pd(II) acceptor with a C2‐symmetric tetrapyridyl donor resulted in the formation of a racemic mixture of the chiral octahedral cage Pd4L2. The existence of this racemic mixture was confirmed using circular dichroism spectroscopy as well as single crystal X‐ray diffraction analysis. We encoded chiral information into the asymmetric cavity of the cage by encapsulating chiral aromatic guests through efficient π‐π stacking and hydrophobic interactions in aqueous media. The inclusion of a chiral guest induces a preference for one enantiomeric conformation of the cage over the other, effectively shifting the equilibrium towards a single, enantiopure host‐guest complex. While the concept of chiral guest recognition by a chiral host is well‐established, this work constitutes a remarkable example of guest‐mediated chirality transfer leading to the formation of a single enantiopure coordination complex from achiral building blocks. [ABSTRACT FROM AUTHOR]

The ability of an octanuclear cubic coordination cage to catalyse a nucleophilic aromatic substitution reaction on a cavity‐bound guest was studied with 2,4‐dinitrofluorobenzene (DNFB) as the guest/substrate. It was found that DNFB undergoes a catalysed reaction with hydroxide ions within the cavity of the cubic cage (in aqueous buffer solution, pH 8.6). The rate enhancement of kcat/kuncat was determined to be 22, with cavity binding of the guest being required for catalysis to occur. The product, 2,4‐dinitrophenolate (DNP), remained bound within the cavity due to electrostatic stabilisation and exerts two apparently contradictory effects: it initially auto‐catalyses the reaction when present at low concentrations, but at higher concentrations inhibits catalysis when a pair of DNP guests block the cavity. When encapsulated, the UV/Vis absorption spectrum of DNP is red‐shifted when compared to the spectrum of free DNP in aqueous solution. Further investigations using other aromatic guests determined that a similar red‐shift on cavity binding also occurred for 4‐nitrophenolate (4NP) at pH 8.6. The red‐shift was used to determine the stoichiometry of guest binding of DNP and 4NP within the cage cavity, which was confirmed by structural analysis with X‐ray crystallography; and was also used to perform catalytic kinetic studies in the solution‐state. [ABSTRACT FROM AUTHOR]

The artificial microenvironments inside coordination cages have gained significant attention for performing enzyme‐like catalytic reactions by facilitating the formation of labile and complex molecules through a "ship‐in‐a‐bottle" approach. Despite many fascinating examples, this approach remains scarcely explored in the context of synthesizing metallic clusters such as polyoxometalates (POMs). The development of innovative approaches to control and influence the speciation of POMs in aqueous solutions would greatly advance their applicability and could ultimately lead to the formation of elusive clusters that cannot be synthesized by using traditional methods. In this study, we employ host–guest stabilization within a coordination cage to enable a novel cavity‐directed synthesis of labile POMs in aqueous solutions under mild conditions. The elusive Lindqvist [M6O19]2− (M=Mo or W) POMs were successfully synthesized at room temperature via the condensation of molybdate or tungstate building blocks within the confined cavity of a robust and water‐soluble Pt6L4(NO3)12 coordination cage. Importantly, the encapsulation of these POMs enhances their stability in water, rendering them efficient catalysts for environmentally friendly and selective sulfoxidation reactions using H2O2 as a green oxidant in a pure aqueous medium. The approach developed in this paper offers a means to synthesize and stabilize the otherwise unstable metal‐oxo clusters in water, which can broaden the scope of their applications. [ABSTRACT FROM AUTHOR]

A series of isostructural supramolecular cages with a rhombic dodecahedron shape have been assembled with distinct metal‐coordination lability (M8Pd6‐MOC‐16, M=Ru2+, Fe2+, Ni2+, Zn2+). The chirality transfer between metal centers generally imposes homochirality on individual cages to enable solvent‐dependent spontaneous resolution of Δ8/Λ8−M8Pd6 enantiomers; however, their distinguishable stereochemical dynamics manifests differential chiral phenomena governed by the cage stability following the order Ru8Pd6>Ni8Pd6>Fe8Pd6>Zn8Pd6. The highly labile Zn centers endow the Zn8Pd6 cage with conformational flexibility and deformation, enabling intrigue chiral‐Δ8/Λ8−Zn8Pd6 to meso‐Δ4Λ4−Zn8Pd6 transition induced by anions. The cage stabilization effect differs from inert Ru2+, metastable Fe2+/Ni2+, and labile Zn2+, resulting in different chiral‐guest induction. Strikingly, solvent‐mediated host–guest interactions have been revealed for Δ8/Λ8−(Ru/Ni/Fe)8Pd6 cages to discriminate the chiral recognition of the guests with opposite chirality. These results demonstrate a versatile procedure to control the stereochemistry of metal‐organic cages based on the dynamic metal centers, thus providing guidance to maneuver cage chirality at a supramolecular level by virtue of the solvent, anion, and guest to benefit practical applications. [ABSTRACT FROM AUTHOR]

Abstract In the energy landscape of coordination‐driven self‐assembly processes, the isolation of kinetically formed supramolecular cages has long been identified as a challenging task. This study reports a reliable strategy for the selective isolation of kinetically or thermodynamically preferred stable coordination cages, whose formation depends on the degree of steric protection offered by the exterior side chains. The combination of PdII ions with arc‐shaped 2,2′‐bianthryl‐based ligands that contain different numbers of methoxyethoxy side chains led to the quantitative formation of both kinetically favorable monomeric M2L4 cages and thermodynamically favorable dimeric (M2L4)2 interlocked cages. These assemblies were structurally fully characterized via NMR spectroscopy, mass spectrometry, and single‐crystal X‐ray diffraction analysis. Although the monomeric cages with fewer exterior side chains can reassemble into interlocked cages, the cages with more exterior substituents remain monomeric cages under similar conditions. A computational study revealed that this different behavior is mainly governed by the destabilization of the interlocking assemblies due to the steric repulsion among the side chains on the overcrowded exterior. Furthermore, the kinetically stabilized monomeric M2L4 cages exhibit permanent host abilities toward sulfonate guests, while the cages with lower steric protection undergo dimerization accompanied by guest release.

To study the fluorescent behavior of quantitatively confined aggregation‐induced emission (AIE) molecules in a giant cavity, herein a new type of coordination‐driven cuboctahedron cage is presented, with 12 AIE molecules anchored endohedrally linked with different‐length alkyl chains. The cage with confined tetraphenylethylene molecules shows strong fluorescence in highly diluted conditions (4 × 10−7 m). The fluorescence quantum yield can be altered from 3.23% up to 81.37%, upon prolonging the length of alkyl chains to C16. The study shows a great potential application in biology mimic and fluorescent microscopes utilizing confined or isolated fluorescent methods. [ABSTRACT FROM AUTHOR]

The design of molecular containers capable of selectively binding specific guest molecules presents an interesting synthetic challenge in supramolecular chemistry. Here, we report the synthesis and structure of a coordination cage assembled from Cu3I4− clusters and tripodal cationic N‐donor ligands. Owing to the localized permanent charges in the ligand core the cage binds iodide anions in specific regions within the cage through ionic interactions. This allows the selective binding of bromomethanes as secondary guest species within the cage promoted by halogen bonding, which was confirmed by single‐crystal X‐ray diffraction. [ABSTRACT FROM AUTHOR]

Coordination cages with well‐defined cavities show great promise in the field of catalysis on account of their unique combination of molecular confinement effects and transition‐metal redox chemistry. Here, three coordination cages are reduced from their native 16+ oxidation state to the 2+ state in the gas phase without observable structural degradation. Using this method, the reaction rate constants for each reduction step were determined, with no noticeable differences arising following either the incorporation of a C60‐fullerene guest or alteration of the cage chemical structure. The reactivity of highly reduced cage species toward molecular oxygen is "switched‐on" after a threshold number of reduction steps, which is influenced by guest molecules and the structure of cage components. These new experimental approaches provide a unique window to explore the chemistry of highly‐reduced cage species that can be modulated by altering their structures and encapsulated guest species. [ABSTRACT FROM AUTHOR]

A novel metal–organic cage 1·8PF6− was precisely self-assembled using polynitrogen pyrazine-triazine ligand as linker L1 and bpyPd(NO3)2 as coordination corner (where 1·8PF6− = [(bpyPd)4L12]8+·8PF6−; L1 = 4, 6-bis((pyrazin-2-ylmethyl)amino)-1,3,5-triazin-2-ol); bpy = 2,2′-bipyridine) in aqueous solution. The capsule-like coordination cage 1·8PF6− was fully characterized by single-crystal X-ray diffraction analysis, 1H and 13C-NMR and ESI–MS analysis. In the crystal structure, cage 1 closely stacked into a stable 3D framework structure with a regular channel. By employment of such crystalline adsorbent material, permanganate anion (MnO4−) can be rapidly adsorbed into cationic channel and exchanged with hexafluorophosphate anion from water, in which the crystallinity of cage 1 remained unaffected before and after adsorption. Moreover, the anion adsorption and exchanging behavior was revealed by Fourier transform infrared spectra (FTIR), powder X-ray diffraction analysis (PXRD), scanning electron microscopy (SEM), electron adsorption and fluorescence spectroscopy. [ABSTRACT FROM AUTHOR]

Heteroleptic (mixed-ligand) coordination cages are of interest as host systems with more structurally and functionally complex cavities than homoleptic architectures. The design of heteroleptic cages, however, is far from trivial. In this work, we experimentally probed the self-assembly of Pd(II) ions with binary ligand combinations in a combinatorial fashion to search for new cis-Pd2L2L'2 heteroleptic cages. A hierarchy of computational analyses was then applied to these systems with the aim of elucidating key factors for rationalising self-assembly outcomes. Simple and inexpensive geometric analyses were shown to be effective in identifying complementary ligand pairs. Preliminary results demonstrated the viability of relatively rapid semi-empirical calculations for predicting the topology of thermodynamically favoured assemblies with rigid ligands, whilst more flexible systems proved challenging. Stemming from this, key challenges were identified for future work developing effective computational forecasting tools for self-assembled metallo-supramolecular systems., (© 2024 Wiley‐VCH GmbH.)

New synthetic routes are presented to derivatives of a (known) M8L12 cubic coordination cage in which a range of different substituents are attached at the C4 position of the pyridyl rings at either end of the bis(pyrazolyl-pyridine) bridging ligands. The substituents are (i) –CN groups (new ligand LCN), (ii) –CH2OCH2–CCH (containing a terminal alkyne) groups (new ligand LCC); and (iii) –(CH2OCH2)3CH2OMe (tri-ethyleneglycol monomethyl ether) groups (new ligand LPEG). The resulting functionalised ligands combine with M2+ ions (particularly Co2+, Ni2+, Cd2+) to give isostructural [M8L12]16+ cage cores bearing 24 external functional groups; the cages based on LCN (with M2+ = Cd2+) and LCC (with M2+ = Ni2+) have been crystallographically characterised. The value of these is twofold: (i) exterior nitrile or alkene substituents can provide a basis for further synthetic opportunities via ‘Click’ reactions allowing in principle a diverse range of functionalisation of the cage exterior surface; (ii) the exterior –(CH2OCH2)3CH2OMe groups substantially increase cage solubility in both water and in organic solvents, allowing binding constants of cavity-binding guests to be measured under an increased range of conditions.

A fluxional bis‐monodentate ligand, based on the archetypal shape‐shifting molecule bullvalene, self‐assembles with M2+ (M=Pd2+ or Pt2+) to produce a highly complex ensemble of permanently fluxional coordination cages. Metal‐mediated self‐assembly selects for an M2L4 architecture while maintaining shape‐shifting ligand complexity. A second level of simplification is achieved with guest‐exchange; the binding of halides within the M2L4 cage mixture results in a convergence to a cage species with all four ligands present as the "B isomer". Within this confine, the reaction graph of the bullvalene is greatly restricted, but gives rise to a mixture of 38 possible diastereoisomers in rapid exchange. X‐ray crystallography reveals a preference for an achiral form consisting of both ligand enantiomers. Through a combination of NMR spectroscopy and DFT calculations, we elucidate the restricted isomerisation pathway of the permanently fluxional M2L4 assembly. [ABSTRACT FROM AUTHOR]

New C3‐symmetric imidazole ligands were designed with phosphine and phosphine oxide linkers (LP and LPO, respectively) to demonstrate a dual‐triggered dynamic closed coordination cage. Both LP and LPO form discrete Zn4L4‐closed cages (1P and 1PO, respectively) with excellent selectively for BPh4−, whereas 1P and 1PO encapsulate neither a slightly larger size anion [B(C6H4CH3)4−] nor smaller size anions (BF4−, PF6−, SbF6−, and OSO2CF3−). 1PO exhibits more negative enthalpy and entropy changes upon anion encapsulation, thus releasing almost all of the encapsulated anions at high temperature (343 K) (trigger 1: BPh4−⊂1PO←→1PO+BPh4−). In contrast 1P has less negative enthalpy and entropy changes, thus preserving the captured anion over a wide range of temperatures (298 K to 343 K). The 1P cage can be quantitatively oxidized to the 1PO cage by a mild oxidant (Ox.=H2O2), and therefore the captured anion can be released by a redox triggering event (trigger 2: BPh4−⊂1P+Ox.→1PO+BPh4−). [ABSTRACT FROM AUTHOR]

New synthetic routes are presented to derivatives of a (known) M8L12 cubic coordination cage in which a range of different substituents are attached at the C4 position of the pyridyl rings at either end of the bis(pyrazolyl-pyridine) bridging ligands. The substituents are (i) –CN groups (new ligand LCN), (ii) –CH2OCH2–CCH (containing a terminal alkyne) groups (new ligand LCC); and (iii) –(CH2OCH2 )3CH2OMe (tri-ethyleneglycol monomethyl ether) groups (new ligand LPEG). The resulting functionalised ligands combine with M2+ ions (particularly Co2+, Ni2+, Cd2+) to give isostructural [M8L12] 16+ cage cores bearing 24 external functional groups; the cages based on LCN (with M2+ = Cd2+) and LCC (with M2+ = Ni2+) have been crystallographically characterised. The value of these is twofold: (i) exterior nitrile or alkene substituents can provide a basis for further synthetic opportunities via ‘Click’ reactions allowing in principle a diverse range of functionalisation of the cage exterior surface; (ii) the exterior –(CH2OCH2 )3CH2OMe groups substantially increase cage solubility in both water and in organic solvents, allowing binding constants of cavity-binding guests to be measured under an increased range of conditions. [ABSTRACT FROM AUTHOR]

Single-particle analysis (SPA) is a fundamental method of cryo-electron microscopy developed to resolve the structures of biological macromolecules. This method has seen significant success in structural biology, yet its potential applications in synthetic chemical systems remain underexplored. In this perspective article, SPA and associated electron microscopy techniques are first briefly introduced. It is then proposed that SPA is well-suited for structural analysis of chemical systems where discrete, identical macromolecules can be readily obtained. Applicable systems include various clusters such as coinage metal clusters, metal-oxo/sulfur clusters, metal-organic clusters, and supramolecular compounds like coordination cages and metallo-supramolecular cages. When high-quality large single crystals are unattainable, SPA provides an alternative method for determining their structures. Beyond these end products, it is suggested that SPA can be instrumental in studying synthetic intermediates of materials with specific building units, such as metal-organic frameworks and zeolites. Given that various intermediates coexist in the reaction system, a purification step is necessary before conducting SPA, which can be facilitated by soft-landing electrospray ionization mass spectrometry., (© 2024 Wiley‐VCH GmbH.)

[Display omitted] • Ultra-small and Highly crystalline metal nanoparticles within the cavity of porous coordination cages. • Face-centered-cubic nanoparticle crystals of noble metal and first-row transition metal species. • Record-high turnover frequency in dehydrogenation reaction of ammonia borane. • Charge effect in stabilizing metal nanoparticles. • Tunable size and morphology of nanoparticles by porous coordination cages. Metal nanoparticles (M NPs) sometimes suffer from low stability and high aggregation, reducing their reactivity during catalytic cycles. In order to obtain stable and ultrafine noble metal (Ru/Rh/Pd) and first-row transition-metal (Co/Ni/Cu) nanoclusters, several porous coordination cages (PCCs) were applied to confine the nanoparticles within their cavities. Because of the electrostatic attraction, metal cations were only encapsulated by PCC-2a with a highly negatively charged cavity. By in situ reduction, M NPs were synthesized within the cavity of PCC-2a to form stable, ultrafine, and highly active catalyst composite. Through characterization by high resolution transmission electron microscope, the synthesized M NPs were found in face-cubic-centered single crystal form, which were rarely reported. In contrast, cages with only 6- negative charges (PCC-2b) or 12+ positive charges (PCC-3) were unable to obtain high crystalline, ultra-small M NPs, resulting in aggregation and large particle size. Finally, the M NPs@PCC catalysts exhibit different activities in methanolysis and hydrolysis of ammonium borane. [ABSTRACT FROM AUTHOR]

• A new zinc-calixarene coordination cage (SWU-3) was synthesized and characterized. • SWU-3 showed highly sensitive and selective detecting capability for Fe3+, CrO 4 2- and Cr 2 O 7 2-. • SWU-3 is an effective sensing probe for detecting I 2. • SWU-3 exhibited high sensitivity detecting ability for NACs. [Display omitted] Solvothermal method was chosen to construct a porous zinc-calixarene coordination cage (SWU-3): [Zn 24 (TC4A-SO 2) 6 (BTC) 8 (H 2 O) 6 ] (H 4 TC4A-SO 2 = p- tert -butylsulfonylcalix[4]arene, H 3 BTC = 1,3,5-benzenetricarboxylic acid) by ZnCl 2 , H 3 BTC and H 4 TC4A-SO 2. SWU-3 shows certain water stability and excellent luminescence property. In the fluorescence test, SWU-3 exhibits different fluorescence sensing behaviors for detecting Fe3+, CrO 4 2-, Cr 2 O 7 2- and iodine (I 2), the LOD values are 2.21 × 10-5, 2.740 × 10-5, 3.066 × 10-5 and 6.673 × 10-6 mol/L, respectively. Moreover, nitroaromatic compounds (NACs) can also be detected by SWU-3. These results prove that SWU-3 reveals great potential as a fluorescence sensor for ions, I 2 and NACs detection. [ABSTRACT FROM AUTHOR]

Most metallo‐supramolecular assemblies of low nuclearity adopt simple topologies, with bridging ligands spanning neighboring metal centers in a direct fashion. Here we contribute a new structural motif to the family of host compounds with low metal count (two) that consists of a pair of doubly‐interlocked, Figure‐eight‐shaped subunits, also termed "lemniscates". Each metal is chelated by two chiral bidentate ligands, composed of a peptidic macrocycle that resembles a natural product with two pyridyl‐terminated arms. DFT calculation results suggest that dimerization of the mononuclear halves is driven by a combination of 1) Coulomb interaction with a central anion, 2) π‐stacking between intertwined ligand arms and 3) dispersive interactions between the structure's compact inner core bedded into an outer shell composed of the cavitand‐type macrocycles. The resulting cage‐like architecture was characterized by NMR, MS and X‐ray structure analyses. This new mechanically bonded system highlights the scope of structural variety accessible in metal‐mediated self‐assemblies composed of only a few constituents. [ABSTRACT FROM AUTHOR]

Self‐assembly of PdX2 (X− = NO3−, BF4−, and CF3SO3−) with 2,6‐bis(4′‐nicotinamidephenoxy)naphthalene (L) forms a series of [Pd2L4]X4 prolate spheroids. The O donors of two Me2SO molecules within the prolate spheroid cage are oriented toward the Pd(II) metal centers. In the presence of H2O2, the nestled Me2SO within the cage is efficiently oxidized to Me2SO2 at room temperature. [ABSTRACT FROM AUTHOR]

A crystallographic investigation of a series of host–guest complexes in which small‐molecule organic guests occupy the central cavity of an approximately cubic M8L12 coordination cage has revealed some unexpected behaviour. Whilst some guests form 1:1 H⋅G complexes as we have seen before, an extensive family of bicyclic guests—including some substituted coumarins and various saturated analogues—form 1:2 H⋅G2 complexes in the solid state, despite the fact that solution titrations are consistent with 1:1 complex formation, and the combined volume of the pair of guests significantly exceeds the Rebek 55±9 % packing for optimal guest binding, with packing coefficients of up to 87 %. Re‐examination of solution titration data for guest binding in two cases showed that, although conventional fluorescence titrations are consistent with 1:1 binding model, alternative forms of analysis—Job plot and an NMR titration—at higher concentrations do provide evidence for 1:2 H⋅G2 complex formation. The observation of guests binding in pairs in some cases opens new possibilities for altered reactivity of bound guests, and also highlights the recently articulated difficulties associated with determining stoichiometry of supramolecular complexes in solution. [ABSTRACT FROM AUTHOR]

A series of isostructural supramolecular cages with a rhombic dodecahedron shape have been assembled with distinct metal-coordination lability (M 8 Pd 6 -MOC-16, M=Ru 2+ , Fe 2+ , Ni 2+ , Zn 2+ ). The chirality transfer between metal centers generally imposes homochirality on individual cages to enable solvent-dependent spontaneous resolution of Δ 8 /Λ 8 -M 8 Pd 6 enantiomers; however, their distinguishable stereochemical dynamics manifests differential chiral phenomena governed by the cage stability following the order Ru 8 Pd 6 >Ni 8 Pd 6 >Fe 8 Pd 6 >Zn 8 Pd 6 . The highly labile Zn centers endow the Zn 8 Pd 6 cage with conformational flexibility and deformation, enabling intrigue chiral-Δ 8 /Λ 8 -Zn 8 Pd 6 to meso-Δ 4 Λ 4 -Zn 8 Pd 6 transition induced by anions. The cage stabilization effect differs from inert Ru 2+ , metastable Fe 2+ /Ni 2+ , and labile Zn 2+ , resulting in different chiral-guest induction. Strikingly, solvent-mediated host-guest interactions have been revealed for Δ 8 /Λ 8 -(Ru/Ni/Fe) 8 Pd 6 cages to discriminate the chiral recognition of the guests with opposite chirality. These results demonstrate a versatile procedure to control the stereochemistry of metal-organic cages based on the dynamic metal centers, thus providing guidance to maneuver cage chirality at a supramolecular level by virtue of the solvent, anion, and guest to benefit practical applications., (© 2023 Wiley-VCH GmbH.)

Host functions of polyaromatic nanocavities were revealed by using an M2L4 molecular cage and capsule. On the basis of the previously reported M2L4 capsule with a closed polyaromatic cavity, a new M2L4 cage (as a mixture of the isomers) was prepared by the quantitative assembly of two metal ions and four desymmetrized bispyridine ligands with a single polyaromatic panel. The obtained, open nanocavity of the cage exhibited enhanced binding abilities toward large dyes and pigments in water. For example, two molecules of coumarin dyes were bound in the nanocavity and showed strong whitish emission (up to ΦF=34 %). Furthermore, metallopigments, the sizes of which are larger than the inner cavities of the cage and capsule, were bound only in the open polyaromatic nanocavity of the cage to give water‐soluble 1:1 host–guest complexes. A new M2L4 polyaromatic cage was quantitatively formed from metal ions and desymmetrized bispyridine ligands with a single polyaromatic panel. The obtained, open nanocavity of the cage exhibited enhanced binding abilities toward large organic dyes in water. Furthermore, metallopigments, the sizes of which are larger than the inner cavities of the cage and an M2L4 polyaromatic capsule, were bound only in the open polyaromatic nanocavity of the cage to give water‐soluble 1:1 host–guest complexes. [ABSTRACT FROM AUTHOR]

A trigonal prismatic Cu6L3 coordination cage has been assembled from Cu(I) and semi‐rigid bipyrazolyl ligand. The X‐ray crystallography demonstrates that the cage has a cavity and can encapsulate the toluene as a guest, exhibiting thermochromism phenomenon. Empty cage can be obtained by expulsion of the guest through single crystal to single crystal transformation. After removed the guest, the empty cage shows a blue‐shifted emission (580 nm), in comparison to its parent cage (615 nm). The empty cage could further serve as a host to encapsulate other aromatic molecules (e. g. mesitylene), which shows new emission band. The trigonal prismatic Cu6L3 coordination cage provides a platform to make advanced luminescent materials. [ABSTRACT FROM AUTHOR]

Graphical abstract Coordination cage: A non-centrosymmetric Y(III) metalloligand was synthesized and used in a Cu(II) ion directed self-assembly to form a Y8/Cu6 heterometallic coordination cage. The cage formation in both solution and in the solid state was demonstrated. Abstract A non-centrosymmetric yttrium [Y(III)] metalloligand, [Y(H 3 L)(NO 3)]·2NO 3 ·THF (1) {tris{[2-{(imidazole)methylidene}amino]-ethyl}amine = H 3 L }, was synthesized and subsequently used in a Cu(II) directed self-assembly process to form a Y8/Cu6- type heterometallic coordination cage [Cu 6 Y 8 L 8 (NO 3) 5 (H 2 O) 3 ]·7NO 3 ·21H 2 O (2). The eight corners of the distorted cubic cage are defined by eight Y(III) ions while Cu(II) ions occupy the centers of six faces with two opposite Cu(II) ions considerably outside the faces. The asymmetric Y(III) metal centres due to the extra coordination of either water molecules or nitrate anions induce chirality in the cage, with equal numbers of both enantiomers present in the solid state. The cage formation in both solution and in the solid state was demonstrated by ESI-MS and single crystal X-ray diffraction. Magnetic property measurements indicate that cage 2 remains paramagnetic down to 2 K. In addition, vibrational modes, electronic structure and thermal stability of the coordination cage 2 have been further investigated and reported. [ABSTRACT FROM AUTHOR]

A high-nuclearity Ni 16 -NH 2 cluster has been fabricated by four Ni 4 -TC4A (H 4 TC4A = p - tert -butylthiacalix[4]arene) polynuclear second-building units and (PSBUs) and eight 5-NH 2 -BDC ligands (5-NH 2 -H 2 BDC = 5-amino-1,3-benzene dicarboxylic acid). The amino-rich Ni 16 -NH 2 cluster was utilized to post-synthesis Ni 16 -Fc-x (x = Fc-CHO/ Ni 16 -NH 2 , X= 1, 2, 4, 8) with Fc-CHO, among which Ni 16 -Fc-4 showed efficient photothermal conversion properties as evidenced by FT-IR, XPS, UV–vis, and EDS measurements. [Display omitted] • Ni 16 -NH 2 can be obtained by the modular assembly of Ni 4 -TC4A (H 4 TC4A = p - tert -butylthiacalix[4]arene) polynuclear second-building units (PSBUs) and eight 5-NH 2 -BDC ligands. • Ni 16 -NH 2 is characterized by a quadrangular arrangement of Ni 4 -TC4A PSBUs with exposed eight –NH 2 groups. • A series of Ni 16 -Fc-x (x = Fc-CHO / Ni 16 -NH 2 , x = 1, 2, 4, 8)) complexes were synthesized by post-modification of Ni 16 -NH 2 with Fc-CHO via the Schiff Base Reaction. • The fabricated Ni 16 -Fc-4/8 exhibited synergistic photothermal conversion properties of the Ni 16 -NH 2 cluster and Fc groups. A high-nuclearity Ni 16 -NH 2 cluster, namely {[Ni 4 (TC4A)Cl] 4 (5-NH 2 -BDC) 8 }[(CH 3) 2 NH 2 ] 4 (+solvents), has been solvothermal synthesized by the modular condense of four Ni 4 -TC4A (H 4 TC4A = p- tert -butylthiacalix[4]arene) polynuclear second-building units (PSBUs) and eight 5-NH 2 -BDC ligands (5-NH 2 -H 2 BDC = 5-amino-1,3-benzene dicarboxylic acid). The Ni 16 -NH 2 is characterized by a quadrangular arrangement of Ni 4 -TC4A PSBUs and two pairs (each of four) exposed –NH 2 groups on both sides of the cluster, which was structurally revealed by single crystal X-ray diffraction determination. A series of Ni 16 -Fc-x (x = [Fc-CHO]/ [Ni 16 -NH 2 ], x = 1, 2, 4, 8) complexes were synthesized by post-modification of Ni 16 -NH 2 with Fc-CHO via the Schiff Base Reaction and characterized by UV–Vis, FT-IR, and XPS measurements. The fabricated Ni 16 -Fc-4/8 exhibited synergistic photothermal conversion properties of the Ni 16 -NH 2 cluster and Fc groups. [ABSTRACT FROM AUTHOR]

The ligand Lan contains two bidentate chelating pyrazolyl-pyridine termini connected to a central aminophenyl ring. In [Ag3(Lan)2](ClO4)3 each ligand coordinates in a pentadentate 2+1+2 manner, connecting all three Ag(I) ions. In contrast, in the octanuclear cubic coordination cage [Co8(Lan)12] [BF4]16 each Lan coordinates as a bis(pyrazolyl-pyridine) tetradentate chelate, with the externallydirected amine groups not coordinated. From its ¹H NMR spectrum this cage has the S6 symmetric structure containing two fac and six mer tris-chelate Co(II) centres of other octanuclear cages. Slow crystallisation afforded [Co8(Lan)12Na][BF4]17, with S4 symmetry arising from four fac and four mer tris-chelate Co(II) centres which alternate; the central cavity accommodates an Na+ cation and four fluoroborate anions which form a {Na(BF4)4}3- guest. The {Na(BF4)4}3- guest forms F•••HN hydrogen bonds through the cage windows with exterior amine groups. Rearrangement of the cage structure from S6 to S4 symmetry appears to facilitate inclusion of the fourfold symmetric guest. [ABSTRACT FROM AUTHOR]

Abstract: Selective anion extraction is useful for the recovery and purification of valuable chemicals, and in the removal of pollutants from the environment. Here we report that FeII4L4 cage 1 is able to extract an equimolar amount of ReO4−, a high‐value anion and a nonradioactive surrogate of TcO4−, from water into nitromethane. Importantly, the extraction was efficiently performed even in the presence of 10 other common anions in water, highlighting the high selectivity of 1 for ReO4−. The extracted guest could be released into water as the cage disassembled in ethyl acetate, and then 1 could be recycled by switching the solvent to acetonitrile. The versatile solubility of the cage also enabled complete extraction of ReO4− (as the tetrabutylammonium salt) from an organic phase into water by using the sulfate salt of 1 as the extractant. [ABSTRACT FROM AUTHOR]

Abstract: Supramolecular containers featuring both high catalytic activity and high enantioselectivity represent a design challenge of practical importance. Herein, it is demonstrated that a chiral octahedral coordination cage can be constructed by using twelve enantiopure Mn(salen)‐derived dicarboxylic acids as linear linkers and six Zn4‐p‐tert‐butylsulfonylcalix[4]arene clusters as tetravalent four‐connected vertices. The porous cage features a large hydrophobic cavity (≈3944 Å3) decorated with catalytically active metallosalen species and is shown to be an efficient and recyclable asymmetric catalyst for the oxidative kinetic resolution of racemic secondary alcohols and the epoxidation of olefins with up to >99 % enantiomeric excess. The cage architecture not only prevents intermolecular deactivation and stabilizes the Mn(salen) catalysts but also encapsulates substrates and concentrates reactants in the cavity, resulting in enhanced reactivity and enantioselectivity relative to the free metallosalen catalyst. [ABSTRACT FROM AUTHOR]

Abstract: The cavity of an M8L12 cubic coordination cage can accommodate a cluster of ten water molecules in which the average number of hydrogen bonds per water molecule is 0.5 H‐bonds less than it would be in the bulk solution. The presence of these “hydrogen‐bond frustrated” or “high‐energy” water molecules in the cavity results in the hydrophobic effect associated with guest binding being predominantly enthalpy‐based, as these water molecules can improve their hydrogen‐bonding environment on release. This contrasts with the classical form of the hydrophobic effect in which the favourable entropy change associated with release of ordered molecules from hydrophobic surfaces dominates. For several guests Van't Hoff plots showed that the free energy of binding in water is primarily enthalpy driven. For five homologous pairs of guests related by the presence or absence of a CH2 group, the incremental changes to ΔH and TΔS for guest binding—that is, ΔΔH and TΔΔS, the difference in contributions arising from the CH2 group—are consistently 5(±1) kJ mol−1 for ΔΔH and 0(±1) kJ mol−1 for TΔΔS. This systematic dominance of ΔH in the binding of hydrophobic guests is consistent with the view that guest binding is dominated by release of “high energy” water molecules into a more favourable solvation environment, as has been demonstrated recently for some members of the cucurbituril family. [ABSTRACT FROM AUTHOR]

A novel Ag 3 L 2 coordination cage was constructed from a tripodal oxazoline-based ligand and exhibited good catalytic performance for the cyclopropanation of styrene with diazo compounds. [Display omitted] • A novel Ag 3 L 2 -type coordination cage was synthesized by using a tripodal oxazoline-based ligand with C 3 symmetry. • The coordination cage generated 3D supramolecular architecture with the pores filled by PF 6 - anions through hydrogen bond, C-H...π and F...Ag interactions. • The Ag 3 L 2 coordination cage exhibited good catalytic performance for the cyclopropanation. Coordination cages have attracted considerable attention recently due to the well-defined cavities and varied potential applications in different fields. In this work, a new tripodal oxazoline-based ligand with C 3 symmetry, tris(4-(4,5-dihydrooxazol-2-yl)phenyl)amine (TOPA), was synthesized and employed to constitute coordination cage compounds. By the reaction of TOPA and AgPF 6 at room temperature, a novel M 3 L 2 -type crystalline coordination cage complex was obtained with the formula of {[Ag 3 (TOPA) 2 ]·(PF 6) 3 }(1). In this complex, the adjacent two ligands coordinated with three Ag+ ions to form a coordination cage and these cages further generate the three-dimensional (3D) supramolecular networks through noncovalent interactions including hydrogen bond, C-H...π and F...Ag interactions. Moreover, cage complex 1 exhibited good catalytic performance in the cyclopropanation of styrene with methyl 2-diazo-2-(4-methoxyphenyl)acetate. [ABSTRACT FROM AUTHOR]

A stable framework has been constructed through multiple charge-assisted H-bonds between cationic coordination cages and chloride ions. The framework maintained its original structure upon desolvation, which has been established by single-crystal structure analysis. This is the first fully characterized stable porous framework based on coordination cages after desolvation, with a moderately high Brunauer-Emmett-Teller (BET) surface area of 1201 m2 g−1. This work will not only give a light to construct stable porous frameworks based on coordination cages and thus broaden their applications, but will also provide a new avenue to the assembly of other porous materials such as porous organic cages and hydrogen-bonded organic frameworks (HOFs) through non covalent bonds. [ABSTRACT FROM AUTHOR]