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The uranyl ion (UO 2 2+ ; U( vi ) oxidation state) is the most common form of uranium found in terrestrial and aquatic environments and is a central component in nuclear fuel processing and waste remediation efforts. Uranyl capture from either seawater or nuclear waste has been well studied and typically relies on extremely strong chelating/binding affinities to UO 2 2+ using chelating polymers 1 , 2 , porous inorganic 3 – 5 or carbon-based 6 , 7 materials, as well as homogeneous 8 compounds. By contrast, the controlled release of uranyl after capture is less established and can be difficult, expensive or destructive to the initial material 2 , 9 . Here we show how harnessing the redox-switchable chelating and donating properties of an ortho -substituted closo -carborane (1,2-(Ph 2 PO) 2 -1,2-C 2 B 10 H 10 ) cluster molecule can lead to the controlled chemical or electrochemical capture and release of UO 2 2+ in monophasic (organic) or biphasic (organic/aqueous) model solvent systems. This is achieved by taking advantage of the increase in the ligand bite angle when the closo -carborane is reduced to the nido -carborane, resulting in C–C bond rupture and cage opening. The use of electrochemical methods for uranyl capture and release may complement existing sorbent and processing systems. Redox-switchable chelation is demonstrated for a carborane cluster molecule, leading to controlled chemical or electrochemical capture and release of uranyl in monophasic or biphasic model solvent systems.

Conductive metal-organic frameworks (MOFs) have performed well in the fields of energy and catalysis, among which two-dimensional (2D) and three-dimensional (3D) MOFs are well-known. Here, we have synthesized a one-dimensional (1D) conductive metal-organic framework (MOF) in which hexacoordinated 1,5-Diamino-4,8-dihydroxy-9,10-anthraceneedione (DDA) ligands are connected by double Cu ions, resulting in nanoribbon layers with 1D π-d conjugated nanoribbon plane and out-of-plane π-π stacking, which facilitates charge transport along two dimensions. The DDA-Cu as a highly conductive n-type MOF has high crystalline quality with a conductivity of ~ 9.4 S·m −1 , which is at least two orders of magnitude higher than that of conventional 1D MOFs. Its electrical band gap (E g ) and exciton binding energy (E b ) are approximately 0.49 eV and 0.3 eV, respectively. When utilized as electrode material in a supercapacitor, the DDA-Cu exhibits good charge storage capacity and cycle stability. Meanwhile, as thse active semiconductor layer, it successfully simulates the artificial visual perception system with excellent bending resistance and air stability as a MOF-based flexible optoelectronic synaptic case. The controllable preparation of high-quality 1D DDA-Cu MOF may enable new architectural designs and various applications in the future. 2D and 3D conductive MOFs have performed well in the fields of energy and catalysis. Here, authors synthesise a 1D conductive MOF in which DDA ligands are connected by double Cu ions, forming nanoribbon layers with π-d conjugated nanoribbon planes and out-of-plane π-π stacking, which facilitates charge transport along two dimensions.

Bright and efficient chiral coinage metal clusters show promise for use in emerging circularly polarized light-emitting materials and diodes. To date, highly efficient circularly polarized organic light-emitting diodes (CP-OLEDs) with enantiopure metal clusters have not been reported. Herein, through rational design of a multidentate chiral N-heterocyclic carbene (NHC) ligand and a modular building strategy, we synthesize a series of enantiopure Au(I)-Cu(I) clusters with exceptional stability. Modulation of the ligands stabilize the chiral excited states of clusters to allow thermally activated delayed fluorescence, resulting in the highest orange-red photoluminescence quantum yields over 93.0% in the solid state, which is accompanied by circularly polarized luminescence. Based on the solution process, a prototypical orange-red CP-OLED with a considerably high external quantum efficiency of 20.8% is prepared. These results demonstrate the extensive designability of chiral NHC ligands to stabilize polymetallic clusters for high performance in chiroptical applications. Chiral coinage metal clusters show promise for use in emerging circularly polarized light-emitting materials and diodes but research on efficient circularly polarized organic light-emitting diodes (CP-OLEDs) with enantiopure metal clusters remains elusive. Herein, the authors design a multidentate chiral N-heterocyclic carbene (NHC) ligand which is used in the synthesis of enantiopure Au(I)-Cu(I) clusters with exceptional stability and demonstrate application of these clusters in the fabrication of CP-OLEDs

Copper hydrides are important hydrogenation catalysts, but their poor stability hinders the practical applications. Ligand engineering is an effective strategy to tackle this issue. An amidinate ligand, N,N′-Di(5-trifluoromethyl-2-pyridyl)formamidinate (Tf-dpf) with four N-donors has been applied as a protecting agent in the synthesis of stable copper hydride clusters: Cu 11 H 3 (Tf-dpf) 6 (OAc) 2 ( Cu 11 ) with three interfacial μ 5 -H and [Cu 12 H 3 (Tf-dpf) 6 (OAc) 2 ]·OAc ( Cu 12 ) with three interstitial μ 6 -H. A solvent-triggered reversible interconversion between Cu 11 and Cu 12 has been observed thanks to the flexibility of Tf-dpf. Cu 11 shows high activity in the reduction of 4-nitrophenol to 4-aminophenol, while Cu 12 displays very low activity. Deuteration experiments prove that the type of hydride is the key in dictating the catalytic activity, for the interfacial μ 5 -H species in Cu 11 are involved in the catalytic cycle whereas the interstitial μ 6 -H species in Cu 12 are not. This work highlights the role of hydrides with regard to catalytic hydrogenation activity. Copper hydrides have been studied for their exciting structural chemistry and applications in hydrogenation catalysis. Here, the authors uncover the role of the amidinate ligand in yielding two closely related copper hydride clusters with quite different catalytic hydrogenation activity.

Using natural gas as chemical feedstock requires efficient oxidation of the constituent alkanes—and primarily methane 1 , 2 . The current industrial process uses steam reforming at high temperatures and pressures 3 , 4 to generate a gas mixture that is then further converted into products such as methanol. Molecular Pt catalysts 5 – 7 have also been used to convert methane to methanol 8 , but their selectivity is generally low owing to overoxidation—the initial oxidation products tend to be easier to oxidize than methane itself. Here we show that N -heterocyclic carbene-ligated Fe II complexes with a hydrophobic cavity capture hydrophobic methane substrate from an aqueous solution and, after oxidation by the Fe centre, release a hydrophilic methanol product back into the solution. We find that increasing the size of the hydrophobic cavities enhances this effect, giving a turnover number of 5.0 × 10 2 and a methanol selectivity of 83% during a 3-h methane oxidation reaction. If the transport limitations arising from the processing of methane in an aqueous medium can be overcome, this catch-and-release strategy provides an efficient and selective approach to using naturally abundant alkane resources. Methane can be oxidized to methanol using N -heterocyclic carbene-ligated Fe II complexes, in which the hydrophobic cavity captures the methane substrate from an aqueous solution and releases the hydrophilic methanol product back into the solution.

Although chirality is an ever-present characteristic in biology and some artificial molecules, controlling the chirality and demystifying the chirality origin of complex assemblies remain challenging. Herein, we report two homochiral Ag 14 nanoclusters with inherent chirality originated from identical rotation of six square faces on a Ag 8 cube driven by intra-cluster π···π stacking interaction between pntp − (Hpntp =  p- nitrothiophenol) ligands. The spontaneous resolution of the racemic (SD/ rac -Ag14a) to homochiral nanoclusters (SD/ L -Ag14 and SD/ R -Ag14) can be realized by re-crystallizing SD/ rac -Ag14a in acetonitrile, which promotes the homochiral crystallization in solid state by forming C–H···O/N hydrogen bonds with nitro oxygen atoms in pntp − or aromatic hydrogen atoms in dpph (dpph = 1,6-bis(diphenylphosphino)hexane) on Ag 14 nanocluster. This work not only provides strategic guidance for the syntheses of chiral silver nanoclusters in an all-achiral environment, but also deciphers the origin of chirality at molecular level by identifying the special effects of intra- and inter-cluster supramolecular interactions. The preparation of chiral monolayer-protected metal clusters is interesting for their potential applications in a variety of fields, including catalysis. Here, the authors synthesize chiral Ag 14 nanoclusters in an all-achiral environment, and decipher the origin of chirality at the molecular level; the solvent choice is key to achieve homochiral crystallization.

Replacing current benchmark rare-element photosensitizers with ones based on abundant and low-cost metals such as iron would help facilitate the large-scale implementation of solar energy conversion. To do so, the ability to extend the lifetimes of photogenerated excited states of iron complexes is critical. Here, we present a sensitizer design in which iron( ii ) centres are supported by frameworks containing benzannulated phenanthridine and quinoline heterocycles paired with amido donors. These complexes exhibit panchromatic absorption and nanosecond charge-transfer excited state lifetimes, enabled by the combination of vacant, energetically accessible heterocycle-based acceptor orbitals and occupied molecular orbitals destabilized by strong mixing between amido nitrogen atoms and iron. This finding shows how ligand design can extend metal-to-ligand charge-transfer-type excited state lifetimes of iron( ii ) complexes into the nanosecond regime and expand the range of potential applications for iron-based photosensitizers. Replacing rare elements in benchmark photosensitizers with iron would facilitate the large-scale implementation of solar energy conversion, but iron complexes generally do not exhibit sufficiently long-lived photoexcited states. Now, it has been shown that iron( ii ) complexes with carefully designed ligands can absorb broadly across the visible light spectrum and have charge-transfer excited states with nanosecond lifetimes.

Any catalyst should be efficient and stable to be implemented in practice. This requirement is particularly valid for manganese hydrogenation catalysts. While representing a more sustainable alternative to conventional noble metal-based systems, manganese hydrogenation catalysts are prone to degrade under catalytic conditions once operation temperatures are high. Herein, we report a highly efficient Mn(I)-CNP pre-catalyst which gives rise to the excellent productivity (TOF° up to 41 000 h −1 ) and stability (TON up to 200 000) in hydrogenation catalysis. This system enables near-quantitative hydrogenation of ketones, imines, aldehydes and formate esters at the catalyst loadings as low as 5–200 p.p.m. Our analysis points to the crucial role of the catalyst activation step for the catalytic performance and stability of the system. While conventional activation employing alkoxide bases can ultimately provide catalytically competent species under hydrogen atmosphere, activation of Mn(I) pre-catalyst with hydride donor promoters, e.g. KHBEt 3 , dramatically improves catalytic performance of the system and eliminates induction times associated with slow catalyst activation. Manganese-based hydrogenation catalysts are sensitive to high temperatures and may degrade under industrially relevant conditions. Here, the authors report a highly efficient manganese pincer pre-catalyst displaying high TOF values (up to 41 000 h −1 ) and stability (TON up to 200 000) at loadings as low as 5-200 ppm.

The advances in determining the total structure of atomically precise metal nanoclusters have prompted extensive exploration into the origins of chirality in nanoscale systems. While chirality is generally transferrable from the surface layer to the metal–ligand interface and kernel, we present here an alternative type of gold nanoclusters (138 gold core atoms with 48 2,4-dimethylbenzenethiolate surface ligands) whose inner structures are not asymmetrically induced by chiral patterns of the outermost aromatic substituents. This phenomenon can be explained by the highly dynamic behaviors of aromatic rings in the thiolates assembled via π − π stacking and C − H···π interactions. In addition to being a thiolate-protected nanocluster with uncoordinated surface gold atoms, the reported Au 138 motif expands the size range of gold nanoclusters having both molecular and metallic properties. Our current work introduces an important class of nanoclusters with intrinsic chirality from surface layers rather than inner structures and will aid in elucidating the transition of gold nanoclusters from their molecular to metallic states. Chiral metal nanoclusters prepared from achiral ligands generally contain chiral kernel structures. Here, the authors report an alternative type of gold nanoclusters whose intrinsic chirality arises solely from the arrangement of the organic components on their surface.

Intensive efforts for the transformation of dinitrogen using transition metal–dinitrogen complexes as catalysts under mild reaction conditions have been made. However, limited systems have succeeded in the catalytic formation of ammonia. Here we show that newly designed and prepared dinitrogen-bridged dimolybdenum complexes bearing N -heterocyclic carbene- and phosphine-based PCP-pincer ligands [{Mo(N 2 ) 2 (PCP)} 2 (μ-N 2 )] ( 1 ) work as so far the most effective catalysts towards the formation of ammonia from dinitrogen under ambient reaction conditions, where up to 230 equiv. of ammonia are produced based on the catalyst. DFT calculations on 1 reveal that the PCP-pincer ligand serves as not only a strong σ -donor but also a π -acceptor. These electronic properties are responsible for a solid connection between the molybdenum centre and the pincer ligand, leading to the enhanced catalytic activity for nitrogen fixation. Catalytic nitrogen fixation is a very active research area, given the need to develop mild routes for ammonia production. Here the authors report a PCP-pincer molybdenum complex allowing for highly efficient ammonia generation under ambient conditions.