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Nature Chemistry

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https://www.readbyqxmd.com/read/27874873/enabling-singlet-fission-by-controlling-intramolecular-charge-transfer-in-%C3%AF-stacked-covalent-terrylenediimide-dimers
#1
Eric A Margulies, Claire E Miller, Yilei Wu, Lin Ma, George C Schatz, Ryan M Young, Michael R Wasielewski
When an assembly of two or more molecules absorbs a photon to form a singlet exciton, and the energetics and intermolecular interactions are favourable, the singlet exciton can rapidly and spontaneously produce two triplet excitons by singlet fission. To understand this process is important because it may prove to be technologically significant for enhancing solar-cell performance. Theory strongly suggests that charge-transfer states are involved in singlet fission, but their role has remained an intriguing puzzle and, up until now, no molecular system has provided clear evidence for such a state...
December 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874872/mechanically-controlled-quantum-interference-in-individual-%C3%AF-stacked-dimers
#2
Riccardo Frisenda, Vera A E C Janssen, Ferdinand C Grozema, Herre S J van der Zant, Nicolas Renaud
Recent observations of destructive quantum interference in single-molecule junctions confirm the role of quantum effects in the electronic conductance properties of molecular systems. These effects are central to a broad range of chemical and biological processes and may be beneficial for the design of single-molecule electronic components to exploit the intrinsic quantum effects that occur at the molecular scale. Here we show that destructive interference can be turned on or off within the same molecular system by mechanically controlling its conformation...
December 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874871/mass-spectrometry-captures-off-target-drug-binding-and-provides-mechanistic-insights-into-the-human-metalloprotease-zmpste24
#3
Shahid Mehmood, Julien Marcoux, Joseph Gault, Andrew Quigley, Susan Michaelis, Stephen G Young, Elisabeth P Carpenter, Carol V Robinson
Off-target binding of hydrophobic drugs can lead to unwanted side effects, either through specific or non-specific binding to unintended membrane protein targets. However, distinguishing the binding of drugs to membrane proteins from that of detergents, lipids and cofactors is challenging. Here, we use high-resolution mass spectrometry to study the effects of HIV protease inhibitors on the human zinc metalloprotease ZMPSTE24. This intramembrane protease plays a major role in converting prelamin A to mature lamin A...
December 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874866/oxadiazole-grafts-in-peptide-macrocycles
#4
John R Frost, Conor C G Scully, Andrei K Yudin
Synthetic methods that provide control over macrocycle conformation and, at the same time, mitigate the polarity of peptide bonds represent valuable tools for the discovery of new bioactive molecules. Here, we report a macrocyclization reaction between a linear peptide, an aldehyde and (N-isocyanimino)triphenylphosphorane. This process generates head-to-tail cyclic peptidomimetics in a single step. This method is tolerant to variation in the peptide and aldehyde components and has been applied for the synthesis of 15-, 18-, 21- and 24-membered rings...
December 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874865/direct-observation-of-subpicosecond-vibrational-dynamics-in-photoexcited-myoglobin
#5
C Ferrante, E Pontecorvo, G Cerullo, M H Vos, T Scopigno
Determining the initial pathway for ultrafast energy redistribution within biomolecules is a challenge, and haem proteins, for which energy can be deposited locally in the haem moiety using short light pulses, are suitable model systems to address this issue. However, data acquired using existing experimental techniques that fail to combine sufficient structural sensitivity with adequate time resolution have resulted in alternative hypotheses concerning the interplay between energy flow among highly excited vibrational levels and potential concomitant electronic processes...
December 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874864/new-ligands-for-nickel-catalysis-from-diverse-pharmaceutical-heterocycle-libraries
#6
Eric C Hansen, Dylan J Pedro, Alexander C Wotal, Nicholas J Gower, Jade D Nelson, Stephane Caron, Daniel J Weix
Ligands are essential for controlling the reactivity and selectivity of reactions catalysed by transition metals. Access to large phosphine ligand libraries has become an essential tool for the application of metal-catalysed reactions industrially, but these existing libraries are not well suited to new catalytic methods based on non-precious metals (for example, Ni, Cu and Fe). The development of the requisite nitrogen- and oxygen-based ligand libraries lags far behind that of the phosphines and the development of new libraries is anticipated to be time consuming...
December 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874862/a-decarboxylative-approach-for-regioselective-hydroarylation-of-alkynes
#7
Jing Zhang, Ruja Shrestha, John F Hartwig, Pinjing Zhao
Regioselective activation of aromatic C-H bonds is a long-standing challenge for arene functionalization reactions such as the hydroarylation of alkynes. One possible solution is to employ a removable directing group that activates one of several aromatic C-H bonds. Here we report a new catalytic method for regioselective alkyne hydroarylation with benzoic acid derivatives during which the carboxylate functionality directs the alkyne to the ortho-C-H bond with elimination in situ to form a vinylarene product...
December 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874861/the-scope-and-mechanism-of-palladium-catalysed-markovnikov-alkoxycarbonylation-of-alkenes
#8
Haoquan Li, Kaiwu Dong, Haijun Jiao, Helfried Neumann, Ralf Jackstell, Matthias Beller
Hydroesterification reactions represent a fundamental type of carbonylation reaction and constitute one of the most important industrial applications of homogeneous catalysis. Over the past 70 years, numerous catalyst systems have been developed that allow for highly linear-selective (anti-Markovnikov) reactions and are used in industry to produce linear carboxylates starting from olefins. In contrast, a general catalyst system for Markovnikov-selective alkoxycarbonylation of aliphatic olefins remains unknown...
December 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874860/targeted-drug-delivery-through-the-traceless-release-of-tertiary-and-heteroaryl-amines-from-antibody-drug-conjugates
#9
Leanna R Staben, Stefan G Koenig, Sophie M Lehar, Richard Vandlen, Donglu Zhang, Josefa Chuh, Shang-Fan Yu, Carl Ng, Jun Guo, Yanzhou Liu, Aimee Fourie-O'Donohue, MaryAnn Go, Xin Linghu, Nathaniel L Segraves, Tao Wang, Jinhua Chen, BinQing Wei, Gail D Lewis Phillips, Keyang Xu, Katherine R Kozak, Sanjeev Mariathasan, John A Flygare, Thomas H Pillow
The reversible attachment of a small-molecule drug to a carrier for targeted delivery can improve pharmacokinetics and the therapeutic index. Previous studies have reported the delivery of molecules that contain primary and secondary amines via an amide or carbamate bond; however, the ability to employ tertiary-amine-containing bioactive molecules has been elusive. Here we describe a bioreversible linkage based on a quaternary ammonium that can be used to connect a broad array of tertiary and heteroaryl amines to a carrier protein...
December 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874874/c-h-activation-good-things-come-in-threes
#10
Marco Simonetti, Igor Larrosa
No abstract text is available yet for this article.
November 22, 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874870/2016-nobel-prize-in-chemistry-molecular-machines
#11
Victoria Richards
No abstract text is available yet for this article.
November 22, 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874869/oriented-electric-fields-as-future-smart-reagents-in-chemistry
#12
Sason Shaik, Debasish Mandal, Rajeev Ramanan
Oriented external electric fields (OEEFs) as 'smart reagents' are no longer a theoretical dream. Here, we discuss the wide-ranging potential of using OEEFs to catalyse and control a variety of non-redox reactions and impart selectivity at will. An OEEF along the direction of electron reorganization (the so-called reaction axis) will catalyse nonpolar reactions by orders of magnitude, control regioselectivity and induce spin-state selectivity. Simply flipping the direction of the OEEF or orienting it off of the reaction axis, will control at will the endo/exo ratio in Diels-Alder reactions and steps in enzymatic cycles...
November 22, 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874868/macrocyclic-peptides-tying-up-loose-ends
#13
Fumito Saito, Jeffrey W Bode
No abstract text is available yet for this article.
November 22, 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874867/einsteinium-declassified
#14
Joanne Redfern
No abstract text is available yet for this article.
November 22, 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27874863/antibody-drug-conjugates-the-missing-link
#15
Tiago Rodrigues, Gonçalo J L Bernardes
No abstract text is available yet for this article.
November 22, 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27768112/observation-of-trapped-hole-diffusion-on-the-surfaces-of-cds-nanorods
#16
James K Utterback, Amanda N Grennell, Molly B Wilker, Orion M Pearce, Joel D Eaves, Gordana Dukovic
In CdS nanocrystals, photoexcited holes rapidly become trapped at the particle surface. The dynamics of these trapped holes have profound consequences for the photophysics and photochemistry of these materials. Using a combination of transient absorption spectroscopy and theoretical modelling, we demonstrate that trapped holes in CdS nanorods are mobile and execute a random walk at room temperature. In CdS nanorods of non-uniform width, we observe the recombination of spatially separated electrons and trapped holes, which exhibits a t(-1/2) power-law decay at long times...
November 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27768111/total-synthesis-and-structure-activity-relationship-studies-of-a-series-of-selective-g-protein-inhibitors
#17
Xiao-Feng Xiong, Hang Zhang, Christina R Underwood, Kasper Harpsøe, Thomas J Gardella, Mie F Wöldike, Michael Mannstadt, David E Gloriam, Hans Bräuner-Osborne, Kristian Strømgaard
G proteins are key mediators of G protein-coupled receptor signalling, which facilitates a plethora of important physiological processes. The cyclic depsipeptides YM-254890 and FR900359 are the only known specific inhibitors of the Gq subfamily of G proteins; however, no synthetic route has been reported previously for these complex natural products and they are not easily isolated from natural sources. Here we report the first total synthesis of YM-254890 and FR900359, as well as of two known analogues, YM-385780 and YM-385781...
November 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27768110/a-stable-heavier-group-14-analogue-of-vinylidene
#18
Arnab Rit, Jesús Campos, Haoyu Niu, Simon Aldridge
Vinylidene (H2C=C) is a member of the family of compounds of composition CH (and isomeric with ethyne, HC≡CH), but it has been observed only transiently-with a lifetime in the region of 0.1 ns. Indeed, no simple (non-base-stabilized) compounds of the type R2E=E have been characterized structurally for any of the group 14 elements. Here we show that by employing the bulky and strongly electron-donating boryl ligand (HCDippN)2B (Dipp, 2,6-(i)Pr2C6H3), a simple monomeric digermavinylidene compound, (boryl)2GeGe, can be synthesized and is stable at room temperature...
November 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27768108/identification-of-s-selective-transaminases-for-the-asymmetric-synthesis-of-bulky-chiral-amines
#19
Ioannis V Pavlidis, Martin S Weiß, Maika Genz, Paul Spurr, Steven P Hanlon, Beat Wirz, Hans Iding, Uwe T Bornscheuer
The use of transaminases to access pharmaceutically relevant chiral amines is an attractive alternative to transition-metal-catalysed asymmetric chemical synthesis. However, one major challenge is their limited substrate scope. Here we report the creation of highly active and stereoselective transaminases starting from fold class I. The transaminases were developed by extensive protein engineering followed by optimization of the identified motif. The resulting enzymes exhibited up to 8,900-fold higher activity than the starting scaffold and are highly stereoselective (up to >99...
November 2016: Nature Chemistry
https://www.readbyqxmd.com/read/27768107/deep-hole-transfer-leads-to-ultrafast-charge-migration-in-dna-hairpins
#20
Nicolas Renaud, Michelle A Harris, Arunoday P N Singh, Yuri A Berlin, Mark A Ratner, Michael R Wasielewski, Frederick D Lewis, Ferdinand C Grozema
Charge transport through the DNA double helix is of fundamental interest in chemistry and biochemistry, but also has potential technological applications such as for DNA-based nanoelectronics. For the latter, it is of considerable interest to explore ways to influence or enhance charge transfer. In this Article we demonstrate a new mechanism for DNA charge transport, namely 'deep-hole transfer', which involves long-range migration of a hole through low-lying electronic states of the nucleobases. Here, we demonstrate, in a combined experimental and theoretical study, that it is possible to achieve such transfer behaviour by changing the energetics of charge injection...
November 2016: Nature Chemistry
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