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Polyhedra are ubiquitous in chemistry, biology, mathematics and other disciplines. Coordination-driven self-assembly has created molecules mimicking Platonic, Archimedean and even Goldberg polyhedra, however, nesting multiple polyhedra in one cluster is challenging, not only for synthesis but also for determining the alignment of the polyhedra. Here, we synthesize a nested Ag 90 nanocluster under solvothermal condition. This pseudo -T h symmetric Ag 90 ball contains three concentric Ag polyhedra with apparently incompatible symmetry. Specifically, the inner (Ag 6 ) and middle (Ag 24 ) shells are octahedral (O h ), an octahedron (a Platonic solid with six 3.3.3.3 vertices) and a truncated octahedron (an Archimedean solid with twenty-four 4.6.6 vertices), whereas the outer (Ag 60 ) shell is icosahedral (I h ), a rhombicosidodecahedron (an Archimedean solid with sixty 3.4.5.4 vertices). The Ag 90 nanocluster solves the apparent incompatibility with the most symmetric arrangement of 2- and 3-fold rotational axes, similar to the arrangement in the model called Kepler’s Kosmos, devised by the mathematician John Conway. Nested polyhedra are compelling but incredibly complex synthetic targets in cluster chemistry. Here, the authors synthesize a Ag 90 nanocluster comprising three concentric polyhedra with apparently incompatible octahedral (O h ) and icosahedral (I h ) symmetry, a mathematical oddity that is solved by the shells’ symmetric arrangement around rotational 2- and 3-fold axes.

A template-free hydrothermal-assisted thermal polymerization method has been developed for the large-scale synthesis of one-dimensional (1D) graphitic carbonnitride (g-C 3 N 4 ) microtubes. The g-C 3 N 4 microtubes were obtained by simple thermal polymerization of melamine-cyanuric acid complex microrods under N 2 atmosphere, which were synthesized by hydrothermal treatment of melamine solution at 180 °C for 24 h. The as-obtained g-C 3 N 4 microtubes exhibited a large surface area and a unique one-dimensional tubular structure, which provided abundant active sites for proton reduction and also facilitated the electron transfer processes. As such, the g-C 3 N 4 microtubes showed enhanced photocatalytic H 2 productionactivity in lactic acid aqueous solutions under visible light irradiation ( λ ≥ 420 nm), which was ∼ 3.1 times higher than that of bulk g-C 3 N 4 prepared by direct thermal polymerization of the melamine precursor under the same calcination conditions.

Vinyl azides, bearing conjugated azide and alkene functional groups, have been recognized as versatile building blocks in organic synthesis. In general vinyl azides act as 3-atom (CCN) synthons through the fast release of molecular nitrogen and have been extensively utilized in the construction of structurally diverse N -heterocycles. Keeping the azide moiety intact in organic transformations to synthesis chiral azides is an important but challenging task. Herein, we report an enantioselective copper(II)/BOX-catalyzed cycloaddition of vinyl azides, generating diverse chiral cyclic azides. α-Aryl substituted vinyl azides react with unsaturated keto esters through an inverse-electron-demand hetero-Diels-Alder reaction to afford chiral azido dihydropyrans with excellent enatioselectivities. In contrast, cyclohexenyl azides undergo a diastereo- and enantio-selective Diels-Alder reaction giving important azido octahydronaphthalenes with three continuous stereogenic centers. Notable features of these reactions include a very broad scope, mild reaction conditions and 100% atom economy. Vinyl azides generally act as 3-atom synthon through the fast release of molecular nitrogen, whereas keeping the azide group intact is more challenging. Here, the authors show a copper-catalyzed enantioselective cycloaddition of two types of vinyl azides generating a diverse pool of valuable chiral cyclic azides.

The structural transformation of high-nuclearity silver clusters from one to another induced by specific stimuli is of scientific significance in terms of both cluster synthesis and reactivity. Herein, we report two silver-thiolate clusters, [Mo 6 O 22 @Ag 44 ] and [Mo 8 O 28 @Ag 50 ], which are templated by isopolymolybdates inside and covered by i PrS − and PhCOO − ligands on the surfaces. Amazingly, the [Mo 8 O 28 @Ag 50 ] can be transformed from [Mo 6 O 22 @Ag 44 ] by adding PhCOOH which increases the degree of condensation of molybdates template from Mo 6 O 22 8- to Mo 8 O 28 8- , then enlarging the outer silver shell from Ag 44 to Ag 50 . The evolution of solution species revealed by time-dependent electrospray ionization mass spectrometry (ESI-MS) suggests a breakage-growth-reassembly (BGR) transformation mechanism. These results not only provide a combined assembly strategy (anion-template + induced transformation) for the synthesis of silver-thiolate clusters but also help us to better understand the complex transformation process underpinning the assembly system. Understanding how one metal nanocluster transforms into another is of synthetic and fundamental importance. Here, the authors use mass spectrometry to reveal an acid-induced structural transformation between two Ag clusters that proceeds via a breakage-growth-reassembly mechanism.

High-nuclearity silver clusters are appealing synthetic targets for their remarkable structures, but most are isolated serendipitously. We report here six giant silver-thiolate clusters mediated by solvents, which not only dictate the formation of an octahedral Ag 6 4+ kernel, but also influence the in situ-generated Mo-based anion templates. The typical sevenfold symmetric silver nanowheels show a hierarchical cluster-in-cluster structure that comprises an outermost Ag 56 shell and an inner Ag 6 4+ kernel in the centre with seven MoO 4 2− anion templates around it. Electrospray ionization mass spectrometry analyses reveal the underlying rule for the formation of such unique silver nanowheels. This work establishes a solvent–intervention approach to construct high-nuclearity silver clusters in which both the formation of octahedral Ag 6 4+ kernel and in situ generation of various Mo-based anion templates can be simultaneously controlled. High-nuclearity silver clusters are appealing synthetic targets for their remarkable structures, but most are isolated serendipitously. Here, the authors describe the rational use of solvents to form cluster-in-cluster silver nanowheels, which comprise an octahedral Ag 6 4+ core surrounded by a Ag 56 cage of unusual seven-fold symmetry.

The enzyme nitrogenase inspires the development of novel photocatalytic and electrocatalytic systems that can drive nitrogen reduction with water under similar low-temperature and low-pressure conditions. While photocatalytic and electrocatalytic N fixation are emerging as hot new areas of fundamental and applied research, serious concerns exist regarding the accuracy of current methods used for ammonia detection and quantification. In most studies, the ammonia yields are low and little consideration is given to the effect of interferants on NH quantification. As a result, NH yields reported in many works may be exaggerated and erroneous. Herein, the advantages and limitations of the various methods commonly used for NH quantification in solution (Nessler's reagent method, indophenol blue method, and ion chromatography method) are systematically explored, placing particular emphasis on the effect of interferants on each quantification method. Based on the data presented, guidelines are suggested for responsible quantification of ammonia in photocatalysis and electrocatalysis.

Sunlight is our most abundant, clean and inexhaustible energy source. However, its diffuse and intermittent nature makes it difficult to use directly, suggesting that we should instead store this energy. One of the most attractive avenues for this involves using solar energy to split H 2 O and afford H 2 through artificial photosynthesis, the practical realization of which requires low-cost, robust photocatalysts. Colloidal quantum dots (QDs) of IIB–VIA semiconductors appear to be an ideal material from which to construct highly efficient photocatalysts for H 2 photogeneration. In this Review, we highlight recent developments in QD-based artificial photosynthetic systems for H 2 evolution using sacrificial reagents. These case studies allow us to introduce strategies — including size optimization, structural modification and surface design — to increase the H 2 evolution activities of QD-based artificial photosystems. Finally, we describe photocatalytic biomass reforming and unassisted photoelectrochemical H 2 O splitting — two new pathways that could make QD-based solar-to-fuel conversion practically viable and cost-effective in the near future. Semiconducting quantum dots (QDs) can serve as light-absorbing components in efficient artificial photosynthetic systems for H 2 evolution. This Review describes how we can optimize QDs for H 2 evolution using sacrificial reductants, before moving on to sustainable strategies for the photolysis of biomass or H 2 O.

Thiacalix[4]arenes as a family of promising ligands have been widely used to construct polynuclear metal clusters, but scarcely employed in silver nanoclusters. Herein, an anion-templated Ag 88 nanocluster (SD/Ag88a) built from p -tert-butylthiacalix[4]arene (H 4 TC4A) is reported. Single-crystal X-ray diffraction reveals that C 4 -symmetric SD/Ag88a resembles a metal-organic super calix comprised of eight TC4A 4− as walls and 88 silver atoms as base, which can be deconstructed to eight [CrO 4 @Ag 11 (TC4A)(EtS) 4 (OAc)] secondary building units arranged in an annulus encircling a CrO 4 2− in the center. Local and global anion template effects from chromates are individually manifested in SD/Ag88a. The solution stability and hierarchical assembly mechanism of SD/Ag88a are studied by using electrospray mass spectrometry. The Ag 88 nanocluster represents the highest nuclearity metal cluster capped by TC4A 4− . This work not only exemplify the specific macrocyclic effects of TC4A 4− in the construction of silver nanocluster but also realize the shape heredity of TC4A 4− to overall silver super calix. The assembly of giant silver clusters by using macrocylic multidentate ligand remains a challenge. Here, the authors synthesize a chromate-templated 88-nuclei silver super calix and reveal the role of anion templating effects and a hierarchical assembly mechanism.

Catalytic hydrogenation or transfer hydrogenation of quinolines was thought to be a direct strategy to access dihydroquinolines. However, the challenge is to control the chemoselectivity and regioselectivity. Here we report an efficient partial transfer hydrogenation system operated by a cobalt-amido cooperative catalyst, which converts quinolines to 1,2-dihydroquinolines by the reaction with H 3 N·BH 3 at room temperature. This methodology enables the large scale synthesis of many 1,2-dihydroquinolines with a broad range of functional groups. Mechanistic studies demonstrate that the reduction of quinoline is controlled precisely by cobalt-amido cooperation to operate dihydrogen transfer from H 3 N·BH 3 to the N=C bond of the substrates. Controlling the partial reduction of quinolines is challenging, given the competing overreduction to tetrahydroquinolines. Here, the authors report a cobalt-amido cooperative catalyst for the selective, partial transfer hydrogenation of quinolines to 1,2-dihydroquinolines with H 3 N·BH 3 as reductant.

Besides its mathematical importance, the Möbius topology (twisted, single-sided strip) is intriguing at the molecular level, as it features structural elegance and distinct properties; however, it carries synthetic challenges. Although some Möbius-type molecules have been isolated by synthetic chemists accompanied by extensive computational studies, the design, preparation, and characterization of stable Möbius-conjugated molecules remain a nontrivial task to date, let alone that of molecular Möbius strips assembling into more complex topologies. Here we report the efficient synthesis, crystal structure, and theoretical study of a catenane consisting of two fully conjugated nanohoops exhibiting Möbius topology in the solid state. This work highlights that oligoparaphenylene-derived nanohoops, a family of highly warped and synthetically challenging conjugated macrocycles, can not only serve as building blocks for interlocked supermolecular structures, but also represent a new class of compounds with isolable Möbius conformations stabilized by non-covalent interactions. Molecules exhibiting Möbius topology are fascinating but challenging synthetic targets. Here, the authors report the elegant synthesis and crystal structure of a catenane formed from two fully conjugated, interlocked Möbius nanohoops, and use theoretical calculations to understand its conformational stability and aromaticity.