pinecone/core-2020-05-10-deduplication huggingface dataset:
Quantitative, In Situ Visualization of Metal-Ion Dissolution and Transport Using (1) H Magnetic Resonance Imaging.

Quantitative mapping of metal ions freely diffusing in solution is important across a diverse range of disciplines and is particularly significant for dissolution processes in batteries, metal corrosion, and electroplating/polishing of manufactured components. However, most current techniques are invasive, requiring sample extraction, insertion of an electrode, application of an electric potential or the inclusion of a molecular sensor. Thus, there is a need for techniques to visualize the distribution of metal ions non-invasively, in situ, quantitatively, in three dimensions (3D) and in real time. Here we have used (1) H magnetic resonance imaging (MRI) to make quantitative 3D maps showing evolution of the distribution of Cu(2+) ions, not directly visible by MRI, during the electrodissolution of copper, with high sensitivity and spatial resolution. The images are sensitive to the speciation of copper, the depletion of dissolved O2 in the electrolyte and show the dissolution of Cu(2+) ions is not uniform across the anode.The authors thank the Leverhulme Trust (grant number RPG-2013-222) and EPSRC (grant number EP/K039245/1) for financial support.Peer-reviewedPublisher Versio
Unveiling (−)-Englerin A as a Modulator of L-Type Calcium Channels

The voltage-dependent L-type Ca$^{2+}$ channel was identified as a macromolecular target for (−)-englerin A. This finding was reached by using an unprecedented ligand-based prediction platform and the natural product piperlongumine as a pharmacophore probe. (−)-Englerin A features high substructure dissimilarity to known ligands for voltage-dependent Ca$^{2+}$ channels, selective binding affinity for the dihydropyridine site, and potent modulation of calcium signaling in muscle cells and vascular tissue. The observed activity was rationalized at the atomic level by molecular dynamics simulations. Experimental confirmation of this hitherto unknown macromolecular target expands the bioactivity space for this natural product and corroborates the effectiveness of chemocentric computational methods for prioritizing target-based screens and identifying binding counterparts of complex natural products.We thank FCT Portugal (FCT Investigator to G.J.L.B. and Postdoctoral Fellowship to P.M.S.D.C.), the European Commission (Marie-Curie CIG to G.J.L.B.), DFG (SI 2117/1-1 to F.S.), the EPSRC and MRC for financial support.This is the author accepted manuscript. The final version is available from Wiley via https://doi.org/10.1002/anie.20160433
Two-coordinate magnesium(I) dimers stabilized by super bulky amido ligands

The authors thank the Australian Research Council (C.J.), The U.S. Air Force Asian Office of Aerospace Research and Development (grant FA2386-14-1-4043 (C.J.)), and the Alexander von Humboldt Foundation for an experienced researcher grant (L.M.).A variety of very bulky amido magnesium iodide complexes, LMgI(solvent)0/1 and [LMg(μ-I)(solvent)0/1]2 (L=-N(Ar)(SiR3); Ar=C6H2{C(H)Ph2}2R′-2,6,4; R=Me, Pri, Ph, or OBut; R′=Pri or Me) have been prepared by three synthetic routes. Structurally characterized examples of these materials include the first unsolvated amido magnesium halide complexes, such as [LMg(μ-I)]2 (R=Me, R′=Pri). Reductions of several such complexes with KC8 in the absence of coordinating solvents have afforded the first two-coordinate magnesium(I) dimers, LMg−MgL (R=Me, Pri or Ph; R′=Pri, or Me), in low to good yields. Reductions of two of the precursor complexes in the presence of THF have given the related THF adduct complexes, L(THF)Mg−Mg(THF)L (R=Me; R′=Pri) and LMg−Mg(THF)L (R=Pri; R′=Me) in trace yields. The X-ray crystal structures of all magnesium(I) complexes were obtained. DFT calculations on the unsolvated examples reveal their Mg−Mg bonds to be covalent and of high s-character, while Ph⋅⋅⋅Mg bonding interactions in the compounds were found to be weak at best.PostprintPeer reviewe
Few-layer antimonene by liquid-phase exfoliation

We report on a fast and simple method to produce highly stable isopropanol/water (4: 1) suspensions of few-layer antimonene by liquid-phase exfoliation of antimony crystals in a process that is assisted by sonication but does not require the addition of any surfactant. This straightforward method generates dispersions of few-layer antimonene suitable for on-surface isolation. Analysis by atomic force microscopy, scanning transmission electron microscopy, and electron energy loss spectroscopy confirmed the formation of high-quality few-layer antimonene nanosheets with large lateral dimensions. These nanolayers are extremely stable under ambient conditions. Their Raman signals are strongly thickness-dependent, which was rationalized by means of density functional theory calculations.EC/FP7/604391/EU/Graphene-Based Revolutions in ICT And Beyond/GRAPHENEEC/FP7/259286/EU/Characterizing and Controlling Carbon Nanomaterials/CCCANDFG, SPP 1459, GrapheneEC/FP7/627386/EU/Multifunctional Graphene by means of a Chemical Approach/MULTIGRAPHCHE
Reversible Electrochemical Modulation of a Catalytic Nanosystem

A catalytic system based on monolayer-functionalized\ud
gold nanoparticles (Au NPs) that can be electrochemically\ud
modulated and reversibly activated is reported. The catalytic\ud
activity relies on the presence of metal ions (Cd2+ and Cu2+),\ud
which can be complexed by the nanoparticle-bound monolayer.\ud
This activates the system towards the catalytic cleavage of\ud
2-hydroxypropyl-p-nitrophenyl phosphate (HPNPP), which\ud
can be monitored by UV/Vis spectroscopy. It is shown that\ud
Cu2+ metal ions can be delivered to the system by applying an\ud
oxidative potential to an electrode on which Cu0 was deposited.\ud
By exploiting the different affinity of Cd2+ and Cu2+ ions for\ud
the monolayer, it was also possible to upregulate the catalytic\ud
activity after releasing Cu2+ from an electrode into a solution\ud
containing Cd2+. Finally, it is shown that the activity of this\ud
supramolecular nanosystem can be reversibly switched on or\ud
off by oxidizing/reducing Cu/Cu2+ ions under controlled\ud
condition
Length-Independent Charge Transport in Chimeric Molecular Wires

Advanced molecular electronic components remain vital for the next generation of miniaturized integrated circuits. Thus, much research effort has been devoted to the discovery of lossless molecular wires, for which the charge transport rate or conductivity is not attenuated with length in the tunneling regime. Herein, we report the synthesis and electrochemical interrogation of DNA-like molecular wires. We determine that the rate of electron transfer through these constructs is independent of their length and propose a plausible mechanism to explain our findings. The reported approach holds relevance for the development of high-performance molecular electronic components and the fundamental study of charge transport phenomena in organic semiconductors
An Epigenetics-Inspired DNA-Based Data Storage System

Biopolymers are an attractive alternative to store and circulate information. DNA, for example, combines remarkable longevity with high data storage densities and has been demonstrated as a means for preserving digital information. Inspired by the dynamic, biological regulation of (epi)genetic information, we herein present how binary data can undergo controlled changes when encoded in synthetic DNA strands. By exploiting differential kinetics of hydrolytic deamination reactions of cytosine and its naturally occurring derivatives, we demonstrate how multiple layers of information can be stored in a single DNA template. Moreover, we show that controlled redox reactions allow for interconversion of these DNA-encoded layers of information. Overall, such interlacing of multiple messages on synthetic DNA libraries showcases the potential of chemical reactions to manipulate digital information on (bio)polymers.C.M. is grateful for the financial support by the Swiss National
Science Foundation (grant number P2EZP2_152216). G.R.M.
was supported by funding from Trinity College, Cambridge,
the Herchel Smith fund and the Wellcome Trust. P.M. was
funded by the Wellcome Trust and is currently supported by
an ERC Advanced grant. P.V.D was funded by the Wellcome
Trust and a Marie Curie Fellow of the European Union (grant number FP7-PEOPLE-2013-IEF/624885). The S.B. lab is
supported by a program grant and core funding from
Cancer Research UK (C9681/A18618), an ERC Advanced
grant (339778) and by a Senior Investigator Award of the
Wellcome Trust (099232/Z/12/Z). We thank Eun-Ang Raiber
and Dario Beraldi for stimulating discussions and proofreading
the manuscript.This is the final version of the article. It first appeared from Wiley at http://dx.doi.org/10.1002/anie.201605531
A Molybdenum(0) Isocyanide Analogue of [Ru(2,2'-Bipyridine)3]2+: Strong Reductant for Photoredox Catalysis

We report the first homoleptic Mo0 complex with bidentate isocyanide ligands, which exhibits metal-to-ligand charge transfer (3MLCT) luminescence with quantum yields and lifetimes similar to Ru(bpy)32+ (bpy=2,2′-bipyridine). This Mo0 complex is a very strong photoreductant, which manifests in its capability to reduce acetophenone with essentially diffusion-limited kinetics as shown by time-resolved laser spectroscopy. The application potential of this complex for photoredox catalysis was demonstrated by the rearrangement of an acyl cyclopropane to a 2,3-dihydrofuran, which is a reaction that requires a reduction potential so negative that even the well-known and strongly reducing Ir(2-phenylpyridine)3 photosensitizer cannot catalyze it. Our study thus provides the proof-of-concept for the use of chelating isocyanides to obtain Mo0 complexes with long-lived 3MLCT excited states that are applicable to unusually challenging photoredox chemistry
Recognition-mediated hydrogel swelling controlled by interaction with a negative thermoresponsive LCST polymer

Most polymeric thermoresponsive hydrogels contract upon heating beyond the lower critical solution temperature (LCST) of the polymers used. Herein, we report a supramolecular hydrogel system that shows the opposite temperature dependence. When the non-thermosesponsive hydrogel NaphtGel, containing dialkoxynaphthalene guest molecules, becomes complexed with the tetra cationic macrocyclic host CBPQT(4+), swelling occurred as a result of host-guest complex formation leading to charge repulsion between the host units, as well as an osmotic contribution of chloride counter-ions embedded in the network. The immersion of NaphtGel in a solution of poly(N-isopropylacrylamide) with tetrathiafulvalene (TTF) end groups complexed with CBPQT(4+) induced positive thermoresponsive behaviour. The LCST-induced dethreading of the polymer-based pseudorotaxane upon heating led to transfer of the CBPQT(4+) host and a concomitant swelling of NaphtGel. Subsequent cooling led to reformation of the TTF-based host-guest complexes in solution and contraction of the hydrogel
Versatile Catalytic Hydrogenation Using A Simple SnIV Lewis Acid

Despite the rapid development of frustrated Lewis pair (FLP) chemistry over the last ten years, its application in catalytic hydrogenations remains dependent on a narrow family of structurally similar early main-group Lewis acids (LAs), inevitably placing limitations on reactivity, sensitivity and substrate scope. Herein we describe the FLP-mediated H2 activation and catalytic hydrogenation activity of the alternative LA iPr3SnOTf, which acts as a surrogate for the trialkylstannylium ion iPr3Sn+, and is rapidly and easily prepared from simple, inexpensive starting materials. This highly thermally robust LA is found to be competent in the hydrogenation of a number of different unsaturated functional groups (which is unique to date for main-group FLP LAs not based on boron), and also displays a remarkable tolerance to moisture
Self-Organized Stationary Patterns in Networks of Bistable Chemical
  Reactions

Experiments with networks of discrete reactive bistable electrochemical
elements organized in regular and nonregular tree networks are presented to
confirm an alternative to the Turing mechanism for the formation of
self-organized stationary patterns. The results show that the pattern formation
can be described by the identification of domains that can be activated
individually or in combinations. The method also enabled the localization of
chemical reactions to network substructures and the identification of critical
sites whose activation results in complete activation of the system. Although
the experiments were performed with a specific nickel electrodissolution
system, they reproduced all the salient dynamic behavior of a general network
model with a single nonlinearity parameter. Thus, the considered
pattern-formation mechanism is very robust, and similar behavior can be
expected in other natural or engineered networked systems that exhibit, at
least locally, a treelike structure
Promoting Difficult C–C Couplings: Which Ligand Does Best?

Producción CientíficaA Pd complex, cis-[Pd(C6 F5 )2 (THF)2 ] (1), is proposed as a useful touchstone for direct and simple experimental measurement of the relative ability of ancillary ligands to induce C-C coupling. Interestingly, 1 is also a good alternative to other precatalysts used to produce Pd0 L. Complex 1 ranks the coupling ability of some popular ligands in the order Pt Bu3 >o-TolPEWO-F≈tBuXPhos>P(C6 F5 )3 ≈PhPEWO-F>P(o-Tol)3 ≈THF≈tBuBrettPhos≫Xantphos≈PhPEWO-H≫PPh3 according to their initial coupling rates, whereas their efficiency, depending on competitive hydrolysis, is ranked tBuXPhos≈Pt Bu3 ≈o-TolPEWO-F>PhPEWO-F>P(C6 F5 )3 ≫tBuBrettPhos>THF≈P(o-Tol)3 >Xantphos>PhPEWO-H≫PPh3 . This "meter" also detects some other possible virtues or complications of ligands such as tBuXPhos or tBuBrettPhos.Ministerio de Economía, Industria y Competitividad (CTQ2013-48406-P)Ministerio de Economía, Industria y Competitividad (CTQ2014-52796-P)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA256U13
Transforming LiTMP lithiation of challenging diazines via gallium alkyl trans-metal-trapping

This study establishes a new trans-metal-trapping (TMT) protocol based on a mixture of LiTMP (the base) and tris(trimethylsilylmethyl)gallium [Ga(CH2SiMe3)3, GaR3] (the trap) that, operating in a tandem manner, is effective for the regioselective deprotonation of sensitive diazines in hydrocarbon solution as illustrated through reactions of pyrazine, pyridazine and pyrimidine, as well as through the N-S heterocycle benzothiazole, the metallo-activated complexes of all of which have been isolated and structurally defined
Structural snapshots for mechanism-based inactivation of a glycoside hydrolase by cyclopropyl-carbasugars

This work was supported by an NSERC Discovery Grant (AJB: #121348-2012), a Wellcome Trust Career Development Fellowship (TMG: grant 095828), a Wellcome Trust Institutional Strategic Support award (TMG and RJP), a MSFHR Career Investigator Award (RB), a NSERC Discovery Grant (RB), and an NSERC PGSM Scholarship (CA).Glycoside hydrolases (GHs) have attracted considerable attention as targets for therapeutic agents, and thus mechanism-based inhibitors are of great interest. We report the first structural analysis of a carbocyclic mechanism-based GH inactivator, the results of which show that the two Michaelis complexes are in 2H3 conformations. We also report the synthesis and reactivity of a fluorinated analogue and the structure of its covalently linked intermediate (flattened 2H3 half-chair). We conclude that these inactivator reactions mainly involve motion of the pseudo-anomeric carbon atom, knowledge that should stimulate the design of new transition-state analogues for use as chemical biology tools.Publisher PDFPeer reviewe
Stereo- and Regioselective Alkyne Hydrometallation with Gold(III) Hydrides

The hydroauration of internal and terminal alkynes by gold(III) hydride complexes [(C^N^C)AuH] was found to be mediated by radicals and proceeds by an unexpected binuclear outer-sphere mechanism to cleanly form trans-insertion products. Radical precursors such as azobisisobutyronitrile lead to a drastic rate enhancement. DFT calculations support the proposed radical mechanism, with very low activation barriers, and rule out mononuclear mechanistic alternatives. These alkyne hydroaurations are highly regio- and stereospecific for the formation of Z-vinyl isomers, with Z/E ratios of >99:1 in most cases
Rich athermal ground-state chemistry triggered by dynamics through a conical intersection.

A fundamental tenet of statistical rate theories (such as transition state theory and RRKM) is the rapidity of vibrational relaxation. Excited-state reactions happen quite quickly (sub-picosecond) and thus can exhibit nonstatistical behavior. However, it is often thought that any diversity of photoproducts results from different conical intersections connecting the excited and ground electronic states. It is also conceivable that the large energy of the photon, which is converted to vibrational energy after electronic transitions could lead to athermal hot ground state reactions and that these might be responsible for the diversity of photoproducts. Here we show that this is the case for sulfines, where a single conical intersection is implicated in the electronic transition but the excited state reaction leads to nine different products within less than a picosecond
Continuous Consecutive Reactions with Inter-Reaction Solvent Exchange via Membrane Separation

Pharmaceutical production typically involves multiple reaction steps with separations between successive reactions. Two processes that complicate the transition from batch to continuous operation in multistep synthesis are solvent exchange (especially high boiling to low boiling point solvent), and catalyst separation. Here we demonstrate membrane separation as an enabling platform for undertaking these processes during continuous operation. Two consecutive reactions are performed in different solvents, with catalyst separation and inter-reaction solvent exchange achieved by continuous flow membrane units. A Heck coupling reaction is performed in DMF in a continuous membrane reactor that retains the catalyst. The Heck reaction product undergoes solvent exchange in a counter-current membrane cascade in which DMF is continuously replaced by ethanol. After the cascade the product dissolved in ethanol passes through a column packed with Fe catalyst, undergoing reduction with >99% yield
Exploiting the imidazolium effect in base-free ammonium enolate generation : synthetic and mechanistic studies

The authors thank the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) ERC Grant Agreement no. 279850 (CMY, THW, JET). ADS thanks the Royal Society for a Wolfson Merit Award.N-Acyl imidazoles and catalytic isothiourea hydrochloride salts function as ammonium enolate precursors in the absence of base. Enantioselective Michael addition-cyclization reactions using different α,β-unsaturated Michael acceptors have been performed to form dihydropyranones and dihydropyridinones with high stereoselectivity. Detailed mechanistic studies using RPKA have revealed the importance of the “imidazolium” effect in ammonium enolate formation and have highlighted key differences with traditional base-mediated processes.PostprintPeer reviewe
Polymer-Lipid Nanoparticles for Systemic Delivery of mRNA to the Lungs

Therapeutic nucleic acids hold great promise for the treatment of disease but require vectors for safe and effective delivery. Synthetic nanoparticle vectors composed of poly(β-amino esters) (PBAEs) and nucleic acids have previously demonstrated potential utility for local delivery applications. To expand this potential utility to include systemic delivery of mRNA, hybrid polymer–lipid nanoformulations for systemic delivery to the lungs were developed. Through coformulation of PBAEs with lipid–polyethylene glycol (PEG), mRNA formulations were developed with increased serum stability and increased in vitro potency. The formulations were capable of functional delivery of mRNA to the lungs after intravenous administration in mice. To our knowledge, this is the first report of the systemic administration of mRNA for delivery to the lungs using degradable polymer–lipid nanoparticles.Shire PharmaceuticalsMIT Skoltech InitiativeNational Cancer Institute (U.S.) (Cancer Center Support (Core) Grant P30-CA14051
Solid separation from a mixed suspension through electric-field-enhanced crystallization

When applied to a pure component suspension in an apolar solvent, a strong inhomogeneous electric field induces particle movement, and the particles are collected at the surface of one of the two electrodes. This new phenomenon was used to separately isolate two organic crystalline compounds, phenazine and caffeine, from their suspension in 1,4-dioxane. First, crystals of both compounds were collected at different electrodes under the influence of an electric field. Subsequent cooling crystallization enabled the immobilization and growth of the particles on the electrodes, which were separately collected after the experiment with purities greater than 91 %. This method can be further developed into a technique for crystal separation and recovery in complex multicomponent suspensions of industrial processes
Fully copper-exchanged high-silica LTA zeolites as unrivaled hydrothermally stable NH3-SCR catalysts

We acknowledge financial support from the National Creative Research Initiative Program (2012R1A3A2048833) through the National Research Foundation of Korea and from Hyundai Motor Group. We also thank J. Y. Koo (POSTECH) for assistance with ESR measurements, K.-S. Lee and Y. H. Jung (8C and 9B, PAL, respectively) for help in X-ray absorption and diffraction data, S. P. Thompson (I11,DLS) for help in obtaining powder X-ray diffraction data, and PAL and DLS for beam time. PAL is supported by MSIP and POSTECH. We acknowledge financial support from the National Creative Research Initiative Program (2012R1A3A2048833) through the National Research Foundation of Korea and from Hyundai Motor Group. We also thank J. Y. Koo (POSTECH) for assistance with ESR measurements, K.-S. Lee and Y. H. Jung (8C and 9B, PAL, respectively) for help in X-ray absorption and diffraction data, S. P. Thompson (I11,DLS) for help in obtaining powder X-ray diffraction data, and PAL and DLS for beam time. PAL is supported by MSIP and POSTECH.Diesel engine technology is still the most effective solution to meet tighter CO2 regulations in the mobility and transport sector. In implementation of fuel-efficient diesel engines, the poor thermal durability of lean nitrogen oxides (NOx) aftertreatment systems remains as one major technical hurdle. Divalent copper ions when fully exchanged into high-silica LTA zeolites are demonstrated to exhibit excellent activity maintenance for NOx reduction with NH3 under vehicle simulated conditions even after hydrothermal aging at 900 °C, a critical temperature that the current commercial Cu-SSZ-13 catalyst cannot overcome owing to thermal deactivation. Detailed structural characterizations confirm the presence of Cu2+ ions only at the center of single 6-rings that act not only as a catalytically active center, but also as a dealumination suppressor. The overall results render the copper-exchanged LTA zeolite attractive as a viable substitute for Cu-SSZ-13.PostprintPostprintPeer reviewe