Extending motifs in lithiocuprate chemistry: unexpected structural diversity in thiocyanate complexes.

The new area of lithio(thiocyanato)cuprates has been developed. Using inexpensive, stable and safe CuSCN for their preparation, these complexes revealed Lipshutz-type dimeric motifs with solvent-dependent point group identities; planar, boat-shaped and chair shaped conformers are seen in the solid state. In solution, both Lipshutz-type and Gilman structures are clearly seen. Since the advent in 2007 of directed ortho cupration, effort has gone into understanding the structure-reactivity effects of amide ligand variation in and alkali metal salt abstraction from Lipshutz-type cuprates such as (TMP)2Cu(CN)Li2(THF) 1 (TMP = 2,2,6,6-tetramethylpiperidide). The replacement of CN(-) with SCN(-) is investigated presently as a means of improving the safety of lithium cuprates. The synthesis and solid state structural characterization of reference cuprate (TMP)2Cu(CN)Li2(THP) 8 (THP = tetrahydropyran) precedes that of the thiocyanate series (TMP)2Cu(SCN)Li2(L) (L = OEt29, THF 10, THP 11). For each of 9-11, preformed TMPLi was combined with CuSCN (2 : 1) in the presence of sub-stoichiometric Lewis base (0.5 eq. wrt Li). The avoidance of Lewis basic solvents incurs formation of the unsolvated Gilman cuprate (TMP)2CuLi 12, whilst multidimensional NMR spectroscopy has evidenced the abstraction of LiSCN from 9-11 in hydrocarbon solution and the in situ formation of Gilman reagents. The synthetic utility of 10 is established in the selective deprotometalation of chloropyridine substrates, including effecting transition metal-free homocoupling in 51-69% yield.This work was supported by the U.K. EPSRC through grant EP/J500380/1 (A. P.) and the Ministère de l'Enseignement Supérieur et de la Recherche scientifique Algérien (M. H.). F. M.This is the final version of the article. It was first available from the Royal Society of Chemistry via http://dx.doi.org/10.1039/C5DT03882

Shaping the Future of Fuel: Monolithic Metal-Organic Frameworks for High-Density Gas Storage.

The environmental benefits of cleaner, gaseous fuels such as natural gas and hydrogen are widely reported. Yet, practical usage of these fuels is inhibited by current gas storage technology. Here, we discuss the wide-ranging potential of gas-fuels to revolutionize the energy sector and introduce the limitations of current storage technology that prevent this transition from taking place. The practical capabilities of adsorptive gas storage using porous, crystalline metal-organic frameworks (MOFs) are examined with regard to recent benchmark results and ultimate storage targets in this field. In particular, the industrial limitations of typically powdered MOFs are discussed while recent breakthroughs in MOF processing are highlighted. We offer our perspective on the future of practical, rather than purely academic, MOF developments in the increasingly critical field of environmental fuel storage

Multicomponent signal unmixing from nanoheterostructures: overcoming the traditional challenges of nanoscale X-ray analysis via machine learning.

The chemical composition of core-shell nanoparticle clusters have been determined through principal component analysis (PCA) and independent component analysis (ICA) of an energy-dispersive X-ray (EDX) spectrum image (SI) acquired in a scanning transmission electron microscope (STEM). The method blindly decomposes the SI into three components, which are found to accurately represent the isolated and unmixed X-ray signals originating from the supporting carbon film, the shell, and the bimetallic core. The composition of the latter is verified by and is in excellent agreement with the separate quantification of bare bimetallic seed nanoparticles.D.R. acknowledges support from the Royal Society’s Newton International Fellowship scheme. B.R.K. thanks the U.K. EPSRC for financial support (EP/J500380/1). F.d.l.P. and C.D. acknowledge funding from the ERC under grant no. 259619 PHOTO EM. P.A.M and P.B. acknowledges financial support from the European Research Council under the European Union’s Seventh Framework Programme (FP7/ 2007-2013)/ERC grant agreement 291522-3DIMAGE. P.A.M. also acknowledges financial support from the European Union’s Seventh Framework Programme of the European Commission: ESTEEM2, contract number 312483.This is the final published version. It first appeared at http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.5b00449

Manipulating morphology and composition in colloidal heterometallic nanopods and nanodendrites.

Branched Pt nanoparticles represent an exciting class of nanomaterials with high surface areas suitable for applications in electrocatalysis. Introducing a second metal can enhance performance and reduce cost. External factors such as capping agents and temperature have been used to offer insights into nanopod formation and to encourage their kinetic evolution. More recently, nanodendrites have been reported, though synthesis has generally been empirical; making controlled variation of morphology while maintaining bimetallic composition an elusive target. We report the combination of Pt with Fe under a range of conditions, yielding individually bimetallic nanoparticles whose construction sheds new light on nanopod and/or nanodendrite formation. Fine control of metal precursor reduction through modulating capping agents, reagents, and temperature initially directs nanopod synthesis. Morphology control is retained while composition is then varied from Pt-rich to Pt-poor. Additionally, conditions are identified that promote the collision-based branching of nanopod arms. This allows synthesis to be redirected for the selective growth of compositionally controlled nanodendrites in predictable fashion

Lipshutz-type bis(amido)argentates for directed ortho argentation.

Bis(amido)argentate (TMP)2Ag(CN)Li2 (3, TMP-Ag-ate; TMP = 2,2,6,6-tetramethylpiperidido) was designed as a tool for chemoselective aromatic functionalization via unprecedented directed ortho argentation (DoAg). X-Ray crystallographic analysis showed that 3 takes a structure analogous to that of the corresponding Lipshutz cuprate. DoAg with this TMP-Ag-ate afforded multifunctional aromatics in high yields in processes that exhibited high chemoselectivity and compatibility with a wide range of functional groups. These included organometallics- and transition metal-susceptible substituents such as methyl ester, aldehyde, vinyl, iodo, (trifluoromethanesulfonyl)oxy and nitro groups. The arylargentates displayed good reactivity with various electrophiles. Chalcogen (S, Se, and Te) installation and azo coupling reactions also proceeded efficiently

A reusable catalyst based on CuO hexapods and a CuO-Ag composite for the highly efficient reduction of nitrophenols.

The enormous and urgent need to explore cost-effective catalysts with high efficiency has always been at the forefront of environmental protection and remediation research. This work develops a novel strategy for the fabrication of reusable CuO-based non-noble metal nanomaterials as high-efficiency catalysts. We report a facile and eco-friendly synthesis of CuO hexapods and CuO-Ag composite using uric acid as a reductant and protectant. Both exhibited high catalytic activity in the hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride (NaBH4), with the CuO-Ag composite showing superior catalytic performance. Notably, the highest turnover frequency of CuO-Ag reached 7.97 × 10-2 s-1, which was much higher than numerous noble-metal nanomaterials. In addition, CuO hexapods and CuO-Ag composite were also shown to act as highly efficient and recyclable catalysts in the degeneration of 4-NP. Both CuO hexapods and the CuO-Ag composite exhibited outstanding catalytic durability, with no significant loss of activity over more than 10 cycles in the hydrogenation of 4-NP

New avenues in the directed deprotometallation of aromatics: recent advances in directed cupration.

Recent advances in the selective deprotometallation of aromatic reagents using alkali metal cuprates are reported. The ability of these synergic bases to effect deprotonation under the influence of a directing group is explored in the context of achieving new and more efficient organic transformations whilst encouraging greater ancillary group tolerance by the base. Developments in our understanding of the structural chemistry of alkali metal cuprates are reported, with both Gilman cuprates of the type R2CuLi and Lipshutz and related cuprates of the type R2Cu(X)Li2 (X = inorganic anion) elucidated and rationalised in terms of ligand sterics. The generation of new types of cuprate motif are introduced through the development of adducts between different classes of cuprate. The use of DFT methods to interrogate the mechanistic pathways towards deprotonative metallation is described. Theoretical modelling of in situ rearrangements undergone by the cuprate base are discussed, with a view to understanding the relationship between R2CuLi and R2Cu(X)Li2, their interconversion and the implications of this for cuprate reactivity. The advent of a new class of adduct between different cuprate types is developed and interpreted in terms of the options for expelling LiX from R2Cu(X)Li2. Applications in the field of medicinal chemistry and (hetero)arene derivatization are explored.Much of this work was supported by the U.K. EPSRC (EP/J500380/1). A.W. would like to acknowledge the graduate students who have contributed to the work in the past (Drs. James Morey and Joanna Haywood) and also the GB Sasakawa and Daiwa Foundations and the Royal Society for support with travel and international collaboration. A.W. and M.U. thank the Japan Society for the Promotion of Science. M.U. acknowledges the personnel who have contributed to the work (Yuichi Hashimoto, Yotaro Matsumoto and Keiichi Hirano, Drs. Shinsuke Komagawa, Shinya Usui and Ching-Yuan Liu, and Professors Shuji Yasuike and Jyoji Kurita). M.U. also thanks Hoansha and KAKENHI (Young Scientist (A), Houga, and Priority Area No. 452 and 459), the Daiichi-Sankyo, Asahi Glass, Mitsubishi, Uehara Memorial, Takeda Science, Sumimoto and NAGASE Science and Technology Foundations. F.C. and F.M. would like to acknowledge the graduate students who have contributed to the work (Dr. Tan Tai Nguyen and Ms. Nada Marquise) and the Agence Nationale de la Recherche (ACTIVATE program) for financial support. F.M. also thanks the Institut Universitaire de France and Rennes Métropole.This version is the author accepted manuscript. The final published version can be found on the publisher's website at: http://pubs.rsc.org/en/Content/ArticleLanding/2014/DT/C4DT01130A#!divAbstrac

Facile synthesis of SnO2-PbS nanocomposites with controlled structure for applications in photocatalysis.

Recent studies have shown that SnO2-based nanocomposites offer excellent electrical, optical, and electrochemical properties. In this article, we present the facile and cost-effective fabrication, characterization and testing of a new SnO2-PbS nanocomposite photocatalyst designed to overcome low photocatalytic efficiency brought about by electron-hole recombination and narrow photoresponse range. The structure is fully elucidated by X-ray diffraction (XRD)/Reitveld refinement, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area analysis, and transmission electron microscopy (TEM). Energy-dispersive X-ray spectroscopy (EDX) spectrum imaging analysis demonstrates the intermixing of SnO2 and PbS to form nanocomposites. A charge separation mechanism is presented that explains how the two semiconductors in junction function synergistically. The efficacy of this new nanocomposite material in the photocatalytic degradation of the toxic dye Rhodamine B under simulated solar irradiation is demonstrated. An apparent quantum yield of 0.217 mol min(-1) W(-1) is calculated with data revealing good catalyst recyclability and that charge separation in SnO2-PbS leads to significantly enhanced photocatalytic activity in comparison to either SnO2 or PbS.A. K. and D. R. acknowledge support from the Royal Society’s Newton International Fellowship scheme. D.R would also like to thank Prof. Paul Midgley for access to the TEM at the University of Cambridge and Prof. Gianluigi Botton for access to the CCEM, a national facility supported by NSERC, the Canada Foundation for Innovation and McMaster University. B. R. K. thanks the UK EPSRC for financial support (EP/J500380/1). Thanks go also to Drs. Tim Jones and Jill Geddes of Schlumberger Gould Research for help with the acquisition of Raman and X-ray photoelectron spectra and to Dr. Zlatko Saracevic of the Department of Chemical Engineering and Biotechnology (University of Cambridge) for help with BET surface area analysis. The authors would also like to thanks Miss Georgina Hutton (University of Cambridge) for valuable discussions and input. Unprocessed data for this paper are available at the University of Cambridge data repository (see https://www.repository.cam.ac.uk/handle/1810/252973). These include some data in the file format .dm3 (HRTEM data), which can be opened using the software program Gatan Digital Micrograph 3.6.5 or similar.This is the final version of the article. It first appeared from the Royal Society of Chemistry via http://dx.doi.org/10.1039/C5NR07036

Visible light photocatalysts from low-grade iron ore: the environmentally benign production of magnetite/carbon (Fe3O4/C) nanocomposites

Magnetite (Fe3O4) nanoparticles coated with dextrose and gluconic acid possessing both super-paramagnetism and excellent optical properties have been productively synthesized through a straightforward, efficient and cost efficient hydrothermal reduction route using Fe3+ as sole metal precursor acquired from accumulated iron ore tailings - a mining waste that usually represents a major environmental threat. Fe3O4/C nanocomposites were fully elucidated by FEGSEM and TEM, revealing a combination of platelets (<1 µm) capped by particles (<10 nm) and magnetite was verified by XPS, which demonstrated also oxygen deficiency. A dextrose/gluconic acid coating was elucidated by Fourier transform-infrared (FT-IR) spectroscopy and Thermogravimetric analysis (TGA). The Fe3O4/C nanocomposites were found to be superparamagnetic at room temperature. Meanwhile, their optical properties were investigated by UV-visible Diffuse reflectance Spectroscopy (UV-vis DRS) and photoluminescence (PL) spectroscopy; an Eg of 1.86 eV was determined and emissions at 612 and 650 nm (ex. 250 nm) were consistent with the XPS identification of oxygen vacancies. The efficacy of the as-synthesized magnetically recoverable magnetite/carbon (Fe3O4/C) nanocomposites has been exhibited in the photocatalytic degradation of the toxic textile (industrial) dye bodactive red BNC-BS

A simple one-step synthetic route to access a range of metal-doped polyoxovanadate clusters.

VO(OiPr)3 is a useful precursor for the synthesis of a range of metal-doped polyoxovanadate (POV) cage compounds, its reactions with hydrated metal salts providing a route to arrangements containing Bi and other main group metals, transition metals and lanthanides. The new POV compounds [Bi2(DMSO)6V12O33Br]2[M(DMSO)6] (2Br-M, M = CoII, NiII, CuII, ZnII) [Bi2(DMSO)6V12O33Cl]2[Ca(DMSO)x]·yDMSO (2Cl-Ca), [Bi2(DMSO)6V12O33Cl]2[LnCl(DMSO)7] (2Cl-Ln, Ln = LaIII, CeIII, EuIII), [Bi2(DMSO)6V10O28F2]3[Bi(DMSO)5]2 (3), [V12O32(DMSO)][Gd(NO3)(DMSO)5.5]2 (4) and [Ln(DMSO)4V12O32Cl][LnCl(DMSO)7] (5Cl-Ln, Ln = CeIII, EuIII) have been structurally characterised, and their properties studied using UV-Vis spectroscopy and cyclic voltammetry. Drop-casting these compounds onto fluorine-doped tin oxide followed by calcination provides a simple approach to thin films of metal-doped BiVO4 or LnVO4, depending on the composition of the cage precursor. The applications of the BiVO4 films as photoanodes for water oxidation is explored, with transition metal doping of BiVO4 improving the activity (∼1.8-2.4 times the photocurrent density of undoped BiVO4 at 1.23 V vs. RHE) while lanthanide or Ca-doping is detrimental.Herchel Smith Research Fund China Scholarship Council Shel