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Nature Chemistry

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https://www.readbyqxmd.com/read/28837180/gallium-rich-pd-ga-phases-as-supported-liquid-metal-catalysts
#1
N Taccardi, M Grabau, J Debuschewitz, M Distaso, M Brandl, R Hock, F Maier, C Papp, J Erhard, C Neiss, W Peukert, A Görling, H-P Steinrück, P Wasserscheid
A strategy to develop improved catalysts is to create systems that merge the advantages of heterogeneous and molecular catalysis. One such system involves supported liquid-phase catalysts, which feature a molecularly defined, catalytically active liquid film/droplet layer adsorbed on a porous solid support. In the past decade, this concept has also been extended to supported ionic liquid-phase catalysts. Here we develop this idea further and describe supported catalytically active liquid metal solutions (SCALMS)...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837178/tyrosine-sulfation-modulates-activity-of-tick-derived-thrombin-inhibitors
#2
Robert E Thompson, Xuyu Liu, Jorge Ripoll-Rozada, Noelia Alonso-García, Benjamin L Parker, Pedro José Barbosa Pereira, Richard J Payne
Madanin-1 and chimadanin are two small cysteine-free thrombin inhibitors that facilitate blood feeding in the tick Haemaphysalis longicornis. Here, we report a post-translational modification-tyrosine sulfation-of these two proteins that is critical for potent anti-thrombotic and anticoagulant activity. Inhibitors produced in baculovirus-infected insect cells displayed heterogeneous sulfation of two tyrosine residues within each of the proteins. One-pot ligation-desulfurization chemistry enabled access to homogeneous samples of all possible sulfated variants of the proteins...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837177/chelation-and-stabilization-of-berkelium-in-oxidation-state-iv
#3
Gauthier J-P Deblonde, Manuel Sturzbecher-Hoehne, Peter B Rupert, Dahlia D An, Marie-Claire Illy, Corie Y Ralston, Jiri Brabec, Wibe A de Jong, Roland K Strong, Rebecca J Abergel
Berkelium (Bk) has been predicted to be the only transplutonium element able to exhibit both +III and +IV oxidation states in solution, but evidence of a stable oxidized Bk chelate has so far remained elusive. Here we describe the stabilization of the heaviest 4+ ion of the periodic table, under mild aqueous conditions, using a siderophore derivative. The resulting Bk(IV) complex exhibits luminescence via sensitization through an intramolecular antenna effect. This neutral Bk(IV) coordination compound is not sequestered by the protein siderocalin-a mammalian metal transporter-in contrast to the negatively charged species obtained with neighbouring trivalent actinides americium, curium and californium (Cf)...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837176/elucidating-bonding-preferences-in-tetrakis-imido-uranate-vi-dianions
#4
Nickolas H Anderson, Jing Xie, Debmalya Ray, Matthias Zeller, Laura Gagliardi, Suzanne C Bart
Actinyl species, [AnO2](2+), are well-known derivatives of the f-block because of their natural occurrence and essential roles in the nuclear fuel cycle. Along with their nitrogen analogues, [An(NR)2](2+), actinyls are characterized by their two strong trans-An-element multiple bonds, a consequence of the inverse trans influence. We report that these robust bonds can be weakened significantly by increasing the number of multiple bonds to uranium, as demonstrated by a family of uranium(VI) dianions bearing four U-N multiple bonds, [M]2[U(NR)4] (M = Li, Na, K, Rb, Cs)...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837175/the-structure-and-binding-mode-of-citrate-in-the-stabilization-of-gold-nanoparticles
#5
Hind Al-Johani, Edy Abou-Hamad, Abdesslem Jedidi, Cory M Widdifield, Jasmine Viger-Gravel, Shiv Shankar Sangaru, David Gajan, Dalaver H Anjum, Samy Ould-Chikh, Mohamed Nejib Hedhili, Andrei Gurinov, Michael J Kelly, Mohamad El Eter, Luigi Cavallo, Lyndon Emsley, Jean-Marie Basset
Elucidating the binding mode of carboxylate-containing ligands to gold nanoparticles (AuNPs) is crucial to understand their stabilizing role. A detailed picture of the three-dimensional structure and coordination modes of citrate, acetate, succinate and glutarate to AuNPs is obtained by (13)C and (23)Na solid-state NMR in combination with computational modelling and electron microscopy. The binding between the carboxylates and the AuNP surface is found to occur in three different modes. These three modes are simultaneously present at low citrate to gold ratios, while a monocarboxylate monodentate (1κO(1)) mode is favoured at high citrate:gold ratios...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837174/stereochemical-plasticity-modulates-cooperative-binding-in-a-co-ii-12l6-cuboctahedron
#6
Felix J Rizzuto, Jonathan R Nitschke
Biomolecular receptors are able to process information by responding differentially to combinations of chemical signals. Synthetic receptors that are likewise capable of multi-stimuli response can form the basis of programmable molecular systems, wherein specific input sequences create distinct outputs. Here we report a pseudo-cuboctahedral assembly capable of cooperatively binding anionic and neutral guest species. The binding of pairs of fullerene guests was observed to effect the all-or-nothing cooperative templation of an S6-symmetric host stereoisomer...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837173/iterative-assembly-line-synthesis-of-polypropionates-with-full-stereocontrol
#7
Teerawut Bootwicha, Julian M Feilner, Eddie L Myers, Varinder K Aggarwal
The polypropionate motif is ubiquitous, being characteristic of the most important family of natural products for human health, the polyketides. Numerous strategies have been devised to construct these molecules with high stereocontrol, but certain stereoisomers remain challenging to prepare. We now describe the development of an iterative assembly line strategy for the construction of polypropionates. An assembly line strategy for the synthesis of deoxypolypropionates has already been described. However, the introduction of carbinol units required the development of new building blocks and new reaction conditions...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837172/incipient-class-ii-mixed-valency-in-a-plutonium-solid-state-compound
#8
Samantha K Cary, Shane S Galley, Matthew L Marsh, David L Hobart, Ryan E Baumbach, Justin N Cross, Jared T Stritzinger, Matthew J Polinski, Laurent Maron, Thomas E Albrecht-Schmitt
Electron transfer in mixed-valent transition-metal complexes, clusters and materials is ubiquitous in both natural and synthetic systems. The degree to which intervalence charge transfer (IVCT) occurs, dependent on the degree of delocalization, places these within class II or III of the Robin-Day system. In contrast to the d-block, compounds of f-block elements typically exhibit class I behaviour (no IVCT) because of localization of the valence electrons and poor spatial overlap between metal and ligand orbitals...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837170/solvent-switchable-continuous-breathing-behaviour-in-a-diamondoid-metal-organic-framework-and-its-influence-on-co2-versus-ch4-selectivity
#9
Elliot J Carrington, Craig A McAnally, Ashleigh J Fletcher, Stephen P Thompson, Mark Warren, Lee Brammer
Understanding the behaviour of flexible metal-organic frameworks (MOFs)-porous crystalline materials that undergo a structural change upon exposure to an external stimulus-underpins their design as responsive materials for specific applications, such as gas separation, molecular sensing, catalysis and drug delivery. Reversible transformations of a MOF between open- and closed-pore forms-a behaviour known as 'breathing'-typically occur through well-defined crystallographic transitions. By contrast, continuous breathing is rare, and detailed characterization has remained very limited...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837168/quantifying-ligand-effects-in-high-oxidation-state-metal-catalysis
#10
Brennan S Billow, Tanner J McDaniel, Aaron L Odom
Catalysis by high-valent metals such as titanium(IV) impacts our lives daily through reactions like olefin polymerization. In any catalysis, optimization involves a careful choice of not just the metal but also the ancillary ligands. Because these choices dramatically impact the electronic structure of the system and, in turn, catalyst performance, new tools for catalyst development are needed. Understanding ancillary ligand effects is arguably one of the most critical aspects of catalyst optimization and, while parameters for phosphines have been used for decades with low-valent systems, a comparable system does not exist for high-valent metals...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837166/chlorodifluoromethane-triggered-formation-of-difluoromethylated-arenes-catalysed-by-palladium
#11
Zhang Feng, Qiao-Qiao Min, Xia-Ping Fu, Lun An, Xingang Zhang
Difluoromethylated aromatic compounds are of increasing importance in pharmaceuticals, agrochemicals and materials. Chlorodifluoromethane (ClCF2H), an inexpensive, abundant and widely used industrial raw material, represents the ideal and most straightforward difluoromethylating reagent, but introduction of the difluoromethyl group (CF2H) from ClCF2H into aromatics has not been reported. Here, we describe a direct palladium-catalysed difluoromethylation method for coupling ClCF2H with arylboronic acids and esters to generate difluoromethylated arenes with high efficiency...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837165/visible-light-excitation-of-iminium-ions-enables-the-enantioselective-catalytic-%C3%AE-alkylation-of-enals
#12
Mattia Silvi, Charlie Verrier, Yannick P Rey, Luca Buzzetti, Paolo Melchiorre
Chiral iminium ions-generated upon condensation of α,β-unsaturated aldehydes and amine catalysts-are used extensively by chemists to make chiral molecules in enantioenriched form. In contrast, their potential to absorb light and promote stereocontrolled photochemical processes remains unexplored. This is despite the fact that visible-light absorption by iminium ions is a naturally occurring event that triggers the mechanism of vision in higher organisms. Herein we demonstrate that the direct excitation of chiral iminium ions can unlock unconventional reaction pathways, enabling enantioselective catalytic photochemical β-alkylations of enals that cannot be realized via thermal activation...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837163/a-31-residue-peptide-induces-aggregation-of-tau-s-microtubule-binding-region-in-cells
#13
Jan Stöhr, Haifan Wu, Mimi Nick, Yibing Wu, Manasi Bhate, Carlo Condello, Noah Johnson, Jeffrey Rodgers, Thomas Lemmin, Srabasti Acharya, Julia Becker, Kathleen Robinson, Mark J S Kelly, Feng Gai, Gerald Stubbs, Stanley B Prusiner, William F DeGrado
The self-propagation of misfolded conformations of tau underlies neurodegenerative diseases, including Alzheimer's. There is considerable interest in discovering the minimal sequence and active conformational nucleus that defines this self-propagating event. The microtubule-binding region, spanning residues 244-372, reproduces much of the aggregation behaviour of tau in cells and animal models. Further dissection of the amyloid-forming region to a hexapeptide from the third microtubule-binding repeat resulted in a peptide that rapidly forms fibrils in vitro...
September 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837179/bonding-with-actinides
#14
Anne Pichon
No abstract text is available yet for this article.
August 24, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837171/the-bottom-line
#15
EDITORIAL
(no author information available yet)
No abstract text is available yet for this article.
August 24, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837169/peaceful-berkelium
#16
Andreas Trabesinger
No abstract text is available yet for this article.
August 24, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837167/organometallic-mechanisms-measuring-up-with-the-early-metals
#17
Ian A Tonks
No abstract text is available yet for this article.
August 24, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28837164/supported-liquid-metal-catalysts-popping-up-to-the-surface
#18
Günther Rupprechter
No abstract text is available yet for this article.
August 24, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28754949/cell-permeable-nanobodies-for-targeted-immunolabelling-and-antigen-manipulation-in-living-cells
#19
Henry D Herce, Dominik Schumacher, Anselm F L Schneider, Anne K Ludwig, Florian A Mann, Marion Fillies, Marc-André Kasper, Stefan Reinke, Eberhard Krause, Heinrich Leonhardt, M Cristina Cardoso, Christian P R Hackenberger
Functional antibody delivery in living cells would enable the labelling and manipulation of intracellular antigens, which constitutes a long-thought goal in cell biology and medicine. Here we present a modular strategy to create functional cell-permeable nanobodies capable of targeted labelling and manipulation of intracellular antigens in living cells. The cell-permeable nanobodies are formed by the site-specific attachment of intracellularly stable (or cleavable) cyclic arginine-rich cell-penetrating peptides to camelid-derived single-chain VHH antibody fragments...
August 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28754948/parameterization-of-phosphine-ligands-demonstrates-enhancement-of-nickel-catalysis-via-remote-steric-effects
#20
Kevin Wu, Abigail G Doyle
The field of Ni-catalysed cross-coupling has seen rapid recent growth because of the low cost of Ni, its earth abundance, and its ability to promote unique cross-coupling reactions. Whereas advances in the related field of Pd-catalysed cross-coupling have been driven by ligand design, the development of ligands specifically for Ni has received minimal attention. Here, we disclose a class of phosphines that enable the Ni-catalysed Csp(3) Suzuki coupling of acetals with boronic acids to generate benzylic ethers, a reaction that failed with known ligands for Ni and designer phosphines for Pd...
August 2017: Nature Chemistry
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