liuxinye

Nanospace functions : Nitrogen‐doped polyaromatic capsules were synthesized from metal ions and pyridine‐embedded, bent anthracene‐based ligands. These capsules display unique host–guest interactions, distinct from those of the undoped analogues. Besides the inclusion of Ag⁺ ions, an absorption change of fullerene C₆₀ and altered emission of a BODIPY dimer are observed upon encapsulation. Moreover, the N‐doped capsule exhibits specific binding abilities toward a natural female and synthetic male hormones.

Abstract

To gain insight into the host functions of a nanocavity encircled by both polyaromatic panels and heteroatoms, nitrogen‐doped polyaromatic capsules were successfully synthesized from metal ions and pyridine‐embedded, bent anthracene‐based ligands. The new capsules display unique host–guest interactions in the isolated cavities, which are distinct from those of the undoped analogues. Besides the inclusion of Ag⁺ ions, the large absorption change of fullerene C₆₀ and altered emission of a BODIPY dimer are observed upon encapsulation by the present hosts. Moreover, the N‐doped capsule exhibits specific binding ability toward progesterone and methyltestosterone, known as a natural female and synthetic male hormone, respectively, in water.

Turn and flip : A C₅₉N⁺ cation has been trapped by ethanol or water in a tubular host to fix an oxy substituent on the fullerene guest. The substituent was found to modulate the guest motion, with the up‐and‐down flipping motions of the guest facilitated by the OH group sliding along the inner wall of the host while staying attached through OH‐π hydrogen bonds, whereas an ethoxy substituent halted such motions.

Abstract

A supramolecular/synthetic method has been devised to affix a sterically hindered substituent onto a fullerene guest encapsulated in a tubular host. A two‐wheeled complex of (C₅₉N)‐(C₅₉N) with a tubular host was oxidatively bisected to afford a C₅₉N⁺ cation captured in the tube. The C₅₉N⁺ cation in the tube was then trapped by ethanol or water, which led to an oxy substituent pinned on the guest. The guest motions within the tube were modulated by the pinned substituent, and up‐and‐down flipping motions were halted by an ethoxy substituent. A hydroxy substituent, however, was ineffective in halting the flipping motions, despite the tight‐fitting relationship between the tubular host and the spherical guest. Theoretical calculations of the dynamics revealed that the flipping motions were assisted by OH‐π hydrogen bonds between the guest and the carbon‐rich wall and that sliding motions of the OH group were also facilitated by deformations of the tube.

Round round get around: A highly efficient metal‐catalyzed tandem cycloaddition reaction enables benzannulation to access cyclopolyarene nanorings of varied sizes from poly(arylene‐butadiynylene) macrocyclic precursors. Unique Möbius topology is manifested by the cyclopolyarene nanorings composed of an odd number of repeat units, whereas cylindrical tubular structures with radial conjugation are formed with an even number of repeat units.

Abstract

By harnessing a highly efficient metal‐catalyzed tandem cycloaddition reaction as the key benzannulation step, a series of cyclopolyarene nanorings of varied sizes are obtained from poly(arylene‐butadiynylene) macrocyclic precursors, which can be synthesized relatively conveniently. Interestingly, due to the nonparallel bond connectivity of the repeat unit, unique Möbius topology is manifested by the cyclopolyarene nanorings composed of an odd number of repeat units, whereas cylindrical tubular structures with radial conjugation are formed with those consisting of an even number of repeat units.

The big bucks: A wide range of fullerenes (buckyballs; C₃₀–C₁₁₄) and their building blocks (buckybowls with a stoichiometry of C_10x H₁₀) were detected in heavy crude oil by ultrahigh‐resolution mass spectrometry. Structural findings are supported by high‐level calculations at the DLPNO‐CCSD(T) level of theory, revealing for the first time the presence of fullerenes in low‐energy fossil materials on a molecular level.

Abstract

Buckyballs (fullerenes) were first reported over 30 years ago, but still little is known regarding their natural occurrence, since they have so far only been found at sites of high‐energy incidents, such as lightning strikes or meteor impacts, but have not been reported in low‐energy materials like fossil fuels. Using ultrahigh‐resolution mass spectrometry, a wide range of fullerenes from C₃₀ to C₁₁₄ was detected in the asphaltene fraction of a heavy crude oil, together with their building blocks of C_10nH₁₀ stoichiometry. High‐level DLPNO‐CCSD(T) calculations corroborate their stability as spherical and hemispherical species. Interestingly, the maximum intensity of the fullerenes was found at C₄₀ instead of the major fullerene C₆₀. Hence, experimental evidence supported by calculations show the existence of not only buckyballs but also buckybowls as 3‐dimensional polyaromatic compounds in fossil materials.

Caught in a web : Inspired by the similarity of the 3D structure of superb‐uranyl binding protein SUP to that of spidroin from spider silk, a chimeric protein, DSUP, containing two copies of SUP was designed and spun into protein fiber. Impressively, the high‐strength DSUP fiber shows ultrahigh, ultrafast, and highly selective uranium extraction ability in natural seawater.

Abstract

The unique three‐dimensional structure of spidrion determines the outstanding mechanical properties of the spider silk fiber. Inspired by the similarity of the three‐dimensional structure of superb‐uranyl binding protein (SUP) to that of spidroin, a dual‐SUP (DSUP) chimeric protein fiber with high tensile strength is designed. The DSUP hydrogel fiber exhibits a loofah‐shape structure by the cross‐interaction of the protein nanofiber. Full exposure of abundant functional uranyl‐binding sites in the stretchable loofah‐shape hydrogel protein fiber give the DSUP fiber a groundbreaking uranium extraction capacity of 17.45 mg g⁻¹ with an ultrashort saturation time of 3 days in natural seawater. This work reports the design of an adsorbent with ultrahigh uranium extraction capacity and explores a strategy for fabricating artificial high‐strength functional non‐spidroin protein fiber.

A diverse group of homoleptic uranium–methyl complexes is presented. The addition of MeLi to UCl₄ at low temperature yields an unprecedented homoleptic uranium–methyl dimer. Overall this complex as well as several other monomeric uranium–alkyl complexes demonstrate the rich coordination and electronic structure and bonding of homoleptic uranium–alkyl complexes with sterically unencumbered alkyl substituents.

Abstract

Homoleptic σ‐bonded uranium–alkyl complexes have been a synthetic target since the Manhattan Project. The current study describes the synthesis and characterization of several unprecedented uranium–methyl complexes. Amongst these complexes, the first example of a homoleptic uranium–alkyl dimer, [Li(THF)₄]₂[U₂(CH₃)₁₀], as well as a seven‐coordinate uranium–methyl monomer, {Li(OEt₂)Li(OEt₂)₂UMe₇Li} _n were both crystallographically identified. The diversity of complexes reported herein provides critical insight into the structural diversity, electronic structure and bonding in uranium–alkyl chemistry.

Dysprosiacarborane complexes based on the interaction between η⁵‐dicarbollide ligands [C₂B₉H₁₁ ²⁻ and (o ‐xylylene‐C₂B₉H₉)²⁻] and the dysprosium(III) cation show large effective energy barriers for slow magnetic relaxation and a magnet‐type hysteresis loop up to 6.8 K, which may provide a new type of organometallic ligand for the design of high‐performance single‐molecule magnets.

Abstract

The dicarbollide ion, nido ‐C₂B₉H₁₁ ²⁻ is isoelectronic with cyclopentadienyl. Herein, we make dysprosiacarboranes, namely [(C₂B₉H₁₁)₂Ln(THF)₂][Na(THF)₅] (Ln=Dy, 1Dy ) and [(THF)₃(μ‐H)₃Li]₂[{η⁵‐C₆H₄(CH₂)₂C₂B₉H₉}Dy{η²:η⁵‐C₆H₄(CH₂)₂C₂B₉H₉}₂Li] 3Dy and show that dicarbollide ligands impose strong magnetic axiality on the central Dy^III ion. The effective energy barrier (U _eff) for the loss of magnetization can be varied by the substitution pattern on the dicarbollide. This finding is demonstrated by comparing complexes of nido ‐C₂B₉H₁₁ ²⁻ and nido ‐[o ‐xylylene‐C₂B₉H₉]²⁻, which show a U _eff of 430(5) K and 804(7) K, respectively. The blocking temperature defined by the open hysteresis temperature of 3Dy reaches 6.8 K. Moreover, the linear complex [Dy(C₂B₉H₁₁)₂]⁻ is predicted to have comparable properties with the linear [Dy(Cp^Me3)₂]⁺ complex. As such, carboranyl ligands and their derivatives may provide a new type of organometallic ligand for high‐performance single‐molecule magnets.

A new route to the classical ylide Ph₃As=CH₂ resolves previous difficulties in its synthesis and isolation. Its structural authentication, 45 years after it was first made, confirms that the ylide is pyramidal not planar, and it enables the synthesis of a uranium–arsonium–carbene, the first structurally characterised example of an arsonium–carbene complex of any metal.

Abstract

Treatment of [Ph₃EMe][I] with [Na{N(SiMe₃)₂}] affords the ylides [Ph₃E=CH₂] (E=As, 1As ; P, 1P ). For 1As this overcomes prior difficulties in the synthesis of this classical arsonium‐ylide that have historically impeded its wider study. The structure of 1As has now been determined, 45 years after it was first convincingly isolated, and compared to 1P , confirming the long‐proposed hypothesis of increasing pyramidalisation of the ylide‐carbon, highlighting the increasing dominance of E⁺−C⁻ dipolar resonance form (sp³‐C) over the E=C ene π‐bonded form (sp²‐C), as group 15 is descended. The uranium(IV)–cyclometallate complex [U{N(CH₂CH₂NSiPrⁱ ₃)₂(CH₂CH₂SiPrⁱ ₂CH(Me)CH₂)}] reacts with 1As and 1P by α‐proton abstraction to give [U(Tren^TIPS)(CHEPh₃)] (Tren^TIPS=N(CH₂CH₂NSiPrⁱ ₃)₃; E=As, 2As ; P, 2P ), where 2As is an unprecedented structurally characterised arsonium‐carbene complex. The short U−C distances and obtuse U‐C‐E angles suggest significant U=C double bond character. A shorter U−C distance is found for 2As than 2P , consistent with increased uranium‐ and reduced pnictonium‐stabilisation of the carbene as group 15 is descended, which is supported by quantum chemical calculations.

The single‐molecule magnets (SMMs) [Cp′₂Dy(μ‐X)]₂ (Cp′=cyclopentadienyltrimethylsilane anion; X=CH₃ ⁻, Cl⁻, Br⁻, I⁻) are investigated. For the first time, the magnetic easy axes of dysprosium metallocene SMMs are experimentally determined, confirming that they are oriented perpendicular to the equatorial plane which is made up of dysprosium and bridging atoms.

Abstract

We investigate a family of dinuclear dysprosium metallocene single‐molecule magnets (SMMs) bridged by methyl and halogen groups [Cp′₂Dy(μ‐X)]₂ (Cp′=cyclopentadienyltrimethylsilane anion; 1 : X=CH₃ ⁻; 2 : X=Cl⁻; 3 : X=Br⁻; 4 : X=I⁻). For the first time, the magnetic easy axes of dysprosium metallocene SMMs are experimentally determined, confirming that the orientation of them are perpendicular to the equatorial plane which is made up of dysprosium and bridging atoms. The orientation of the magnetic easy axis for 1 deviates from the normal direction (by 10.3°) due to the stronger equatorial interactions between Dy^III and methyl groups. Moreover, its magnetic axes show a temperature‐dependent shifting, which is caused by the competition between exchange interactions and Zeeman interactions. Studies of fluorescence and specific heat as well as ab initio calculations reveal the significant influences of the bridging ligands on their low‐lying exchange‐based energy levels and, consequently, low‐temperature magnetic properties.

In order to investigate the nature and strength of noncovalent interactions at the fullerene surface, molecular torsion balances consisting of C60 and organic moieties connected through a biphenyl linkage were designed, synthesized, and characterized. NMR spectroscopy combined with computational studies showed that the unimolecular system remains in equilibrium between well‐defined folded and unfolded conformers owing to restricted rotation around the biphenyl C–C bond. The measured energy differences between the two conformers depend on the substituents and can, in turn, be ascribed to the differences in the intramolecular noncovalent interactions between the organic moieties and the fullerene surface. Notably, the results showed that fullerenes favor interacting with the p‐faces of benzenes bearing electron‐donating substituents. The correlation between the folding free energies and the corresponding Hammett constants of the substituents in the arene‐containing torsion balances is reflective of the contributions of the electrostatic interactions and dispersion force to the face‐to‐face arene–fullerene interactions.

The first f‐block ‐[1]ruthenocenophane complexes are reported and their dynamic magnetic properties are compared to those of their ferrocenophane congeners, which can be considered axially compressed analogues. Axial elongation affects the barrier of magnetization reversal for Dy³⁺ (increase) and Tb³⁺ (decrease) differently. These opposing trends are rationalized by ab initio computations.

Abstract

We report the first f‐block‐ruthenocenophane complexes 1 (Dy) and 2 (Tb) and provide a comparative discussion of their magnetic structure with respect to earlier reported ferrocenophane analogues. While axial elongation of the rare trigonal‐prismatic geometry stabilizes the magnetic ground state in the case of Dy³⁺ and results in a larger barrier to magnetization reversal (U ), a decrease in U is observed for the case of Tb³⁺.

Please don′t you rock my boat : A highly curved boat‐shaped molecule was synthesized by the cyclization of fjords of a bisacridone derivative. Analysis of the structure and properties reveals a stepwise inversion process, red shifts in the absorption and emission spectra, an enhanced emission intensity and a convergence of frontier molecular orbital energy levels in comparison to those of the related concave N ‐heterotriangulene.

Abstract

The surface extension of all‐carbon based bowl‐shaped molecules, such as corannulene and sumanene, to synthesize even larger buckybowls has been widely studied, leaving other concave compounds with heteroatoms less considered. Herein we present a highly curved molecule synthesized via stepwise cyclization of fjords of a bisacridone derivative. Crystallographic analysis unambiguously confirmed a boat‐shaped structure with deformed bottom benzene ring. Theoretical calculation unravels an inversion process with an S‐shaped transition structure rather than a planar one. The enlarged boat demonstrates interesting properties, such as red shifts in absorption and emission spectra, enhanced emission intensity, and convergent frontier molecular orbital energy levels, in comparison to the related concave N ‐heterotriangulene.

Well balanced : A fullerene‐based molecular torsion balance is constructed to investigate noncovalent arene–fullerene interactions. The interactions are weak but measurable. The linear correlation between the difference in the free energies of two well‐defined conformers and the Hammett constants of the substituents on the arene moieties indicate that the electrostatic interactions are a significant contribution.

Abstract

To investigate the nature and strength of noncovalent interactions at the fullerene surface, molecular torsion balances consisting of C₆₀ and organic moieties connected through a biphenyl linkage were synthesized. NMR and computational studies show that the unimolecular system remains in equilibrium between well‐defined folded and unfolded conformers owing to restricted rotation around the biphenyl C−C bond. The energy differences between the two conformers depend on the substituents and is ascribed to differences in the intramolecular noncovalent interactions between the organic moieties and the fullerene surface. Fullerenes favor interacting with the π‐faces of benzenes bearing electron‐donating substituents. The correlation between the folding free energies and corresponding Hammett constants of the substituents in the arene‐containing torsion balances reflects the contributions of the electrostatic interactions and dispersion force to face‐to‐face arene–fullerene interactions.

Single‐Molecule Magnets In their Communication on https://doi.org/10.1002/anie.201914728page 8818, L. Scherthan, A. K. Powell, V. Schünemann et al. present a nuclear resonance spectroscopic technique to study the vibrational properties of a single‐molecule magnet containing dysprosium(III).

Nanoparticle Assemblies N. A. Kotov et al. show in their Research Article on https://doi.org/10.1002/anie.201908216page 8542 how graphene quantum dots can assemble into complex structures in a process driven by coordination interactions with metal ions.

Nature Communications, Published online: 14 May 2020; doi:10.1038/s41467-020-16377-4

The single‐molecule magnets (SMMs) [Cp′₂Dy(μ‐X)]₂ (Cp′=cyclopentadienyltrimethylsilane anion; X=CH₃ ⁻, Cl⁻, Br⁻, I⁻) are investigated. For the first time, the magnetic easy axes of dysprosium metallocene SMMs are experimentally determined, confirming that they are oriented perpendicular to the equatorial plane which is made up of dysprosium and bridging atoms.

Abstract

We investigate a family of dinuclear dysprosium metallocene single‐molecule magnets (SMMs) bridged by methyl and halogen groups [Cp′₂Dy(μ‐X)]₂ (Cp′=cyclopentadienyltrimethylsilane anion; 1 : X=CH₃ ⁻; 2 : X=Cl⁻; 3 : X=Br⁻; 4 : X=I⁻). For the first time, the magnetic easy axes of dysprosium metallocene SMMs are experimentally determined, confirming that the orientation of them are perpendicular to the equatorial plane which is made up of dysprosium and bridging atoms. The orientation of the magnetic easy axis for 1 deviates from the normal direction (by 10.3°) due to the stronger equatorial interactions between Dy^III and methyl groups. Moreover, its magnetic axes show a temperature‐dependent shifting, which is caused by the competition between exchange interactions and Zeeman interactions. Studies of fluorescence and specific heat as well as ab initio calculations reveal the significant influences of the bridging ligands on their low‐lying exchange‐based energy levels and, consequently, low‐temperature magnetic properties.