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Nature Chemistry

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https://www.readbyqxmd.com/read/29256515/bioinspired-chemical-synthesis-of-monomeric-and-dimeric-stephacidin-a-congeners
#1
Ken Mukai, Danilo Pereira de Sant'Ana, Yasuo Hirooka, Eduardo V Mercado-Marin, David E Stephens, Kevin G M Kou, Sven C Richter, Naomi Kelley, Richmond Sarpong
Stephacidin A and its congeners are a collection of secondary metabolites that possess intriguing structural motifs. They stem from unusual biosynthetic sequences that lead to the incorporation of a prenyl or reverse-prenyl group into a bicyclo[2.2.2]diazaoctane framework, a chromene unit or the vestige thereof. To complement biosynthetic studies, which normally play a significant role in unveiling the biosynthetic pathways of natural products, here we demonstrate that chemical synthesis can provide important insights into biosynthesis...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256512/atomic-resolution-of-structural-changes-in-elastic-crystals-of-copper-ii-acetylacetonate
#2
Anna Worthy, Arnaud Grosjean, Michael C Pfrunder, Yanan Xu, Cheng Yan, Grant Edwards, Jack K Clegg, John C McMurtrie
Single crystals are typically brittle, inelastic materials. Such mechanical responses limit their use in practical applications, particularly in flexible electronics and optical devices. Here we describe single crystals of a well-known coordination compound-copper(II) acetylacetonate-that are flexible enough to be reversibly tied into a knot. Mechanical measurements indicate that the crystals exhibit an elasticity similar to that of soft materials such as nylon, and thus display properties normally associated with both hard and soft matter...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256511/chromophore-twisting-in-the-excited-state-of-a-photoswitchable-fluorescent-protein-captured-by-time-resolved-serial-femtosecond-crystallography
#3
Nicolas Coquelle, Michel Sliwa, Joyce Woodhouse, Giorgio Schirò, Virgile Adam, Andrew Aquila, Thomas R M Barends, Sébastien Boutet, Martin Byrdin, Sergio Carbajo, Eugenio De la Mora, R Bruce Doak, Mikolaj Feliks, Franck Fieschi, Lutz Foucar, Virginia Guillon, Mario Hilpert, Mark S Hunter, Stefan Jakobs, Jason E Koglin, Gabriela Kovacsova, Thomas J Lane, Bernard Lévy, Mengning Liang, Karol Nass, Jacqueline Ridard, Joseph S Robinson, Christopher M Roome, Cyril Ruckebusch, Matthew Seaberg, Michel Thepaut, Marco Cammarata, Isabelle Demachy, Martin Field, Robert L Shoeman, Dominique Bourgeois, Jacques-Philippe Colletier, Ilme Schlichting, Martin Weik
Chromophores absorb light in photosensitive proteins and thereby initiate fundamental biological processes such as photosynthesis, vision and biofluorescence. An important goal in their understanding is the provision of detailed structural descriptions of the ultrafast photochemical events that they undergo, in particular of the excited states that connect chemistry to biological function. Here we report on the structures of two excited states in the reversibly photoswitchable fluorescent protein rsEGFP2. We populated the states through femtosecond illumination of rsEGFP2 in its non-fluorescent off state and observed their build-up (within less than one picosecond) and decay (on the several picosecond timescale)...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256510/direct-observation-of-sequential-oxidations-of-a-titania-bound-molecular-proxy-catalyst-generated-through-illumination-of-molecular-sensitizers
#4
Hsiang-Yun Chen, Shane Ardo
Natural photosynthesis uses the energy in sunlight to oxidize or reduce reaction centres multiple times, therefore preparing each reaction centre for a multiple-electron-transfer reaction that will ultimately generate stable reaction products. This process relies on multiple chromophores per reaction centre to quickly generate the active state of the reaction centre and to outcompete deleterious charge recombination. Using a similar design principle, we report spectroscopic evidence for the generation of a twice-oxidized TiO2-bound molecular proxy catalyst after low-intensity visible-light excitation of co-anchored molecular Ru(II)-polypyridyl dyes...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256509/dynamic-covalent-chemistry-enables-formation-of-antimicrobial-peptide-quaternary-assemblies-in-a-completely-abiotic-manner
#5
James F Reuther, Justine L Dees, Igor V Kolesnichenko, Erik T Hernandez, Dmitri V Ukraintsev, Rusheel Guduru, Marvin Whiteley, Eric V Anslyn
Naturally occurring peptides and proteins often use dynamic disulfide bonds to impart defined tertiary/quaternary structures for the formation of binding pockets with uniform size and function. Although peptide synthesis and modification are well established, controlling quaternary structure formation remains a significant challenge. Here, we report the facile incorporation of aryl aldehyde and acyl hydrazide functionalities into peptide oligomers via solid-phase copper-catalysed azide-alkyne cycloaddition (SP-CuAAC) click reactions...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256508/designing-cooperatively-folded-abiotic-uni-and-multimolecular-helix-bundles
#6
Soumen De, Bo Chi, Thierry Granier, Ting Qi, Victor Maurizot, Ivan Huc
Abiotic foldamers, that is foldamers that have backbones chemically remote from peptidic and nucleotidic skeletons, may give access to shapes and functions different to those of peptides and nucleotides. However, design methodologies towards abiotic tertiary and quaternary structures are yet to be developed. Here we report rationally designed interactional patterns to guide the folding and assembly of abiotic helix bundles. Computational design facilitated the introduction of hydrogen-bonding functionalities at defined locations on the aromatic amide backbones that promote cooperative folding into helix-turn-helix motifs in organic solvents...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256506/mechanism-based-enhancement-of-scope-and-enantioselectivity-for-reactions-involving-a-copper-substituted-stereogenic-carbon-centre
#7
Jaehee Lee, Suttipol Radomkit, Sebastian Torker, Juan Del Pozo, Amir H Hoveyda
A rapidly emerging set of catalytic reactions involves intermediates that contain a copper-substituted stereogenic carbon centre. Here, we demonstrate that an intimate understanding of this distinction provides ways for addressing limitations in reaction scope and explaining why unexpected variations in enantioselectivity often occur. By using catalytic enantioselective Cu-boryl addition to alkenes as the model process, we elucidate several key mechanistic principles. We show that higher electrophile concentration can lead to elevated enantioselectivity...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256505/multi-electron-transfer-photochemistry-caught-in-the-act
#8
Anna M Beiler, Gary F Moore
No abstract text is available yet for this article.
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256504/organocatalytic-asymmetric-arylation-of-indoles-enabled-by-azo-groups
#9
Liang-Wen Qi, Jian-Hui Mao, Jian Zhang, Bin Tan
Arylation is a fundamental reaction that can be mostly fulfilled by electrophilic aromatic substitution and transition-metal-catalysed aryl functionalization. Although the azo group has been used as a directing group for many transformations via transition-metal-catalysed aryl carbon-hydrogen (C-H) bond activation, there remain significant unmet challenges in organocatalytic arylation. Here, we show that the azo group can effectively act as both a directing and activating group for organocatalytic asymmetric arylation of indoles via formal nucleophilic aromatic substitution of azobenzene derivatives...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256503/synthetic-nat-or-ent-steroids-in-as-few-as-five-chemical-steps-from-epichlorohydrin
#10
Wan Shin Kim, Kang Du, Alan Eastman, Russell P Hughes, Glenn C Micalizio
Today, more than 100 Food and Drug Administration-approved steroidal agents are prescribed daily for indications including heart failure, inflammation, pain and cancer. While triumphs in organic chemistry have enabled the establishment and sustained growth of the steroid pharmaceutical industry, the production of highly functionalized synthetic steroids of varying substitution and stereochemistry remains challenging, despite the numerous reports of elegant strategies for their de novo synthesis. Here, we describe an advance in chemical synthesis that has established an enantiospecific means to access novel steroids with unprecedented facility and flexibility through the sequential use of two powerful ring-forming reactions: a modern metallacycle-mediated annulative cross-coupling and a new acid-catalysed vinylcyclopropane rearrangement cascade...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256501/late-stage-chemoselective-functional-group-manipulation-of-bioactive-natural-products-with-super-electrophilic-silylium-ions
#11
Trandon A Bender, Philippa R Payne, Michel R Gagné
The selective (and controllable) modification of complex molecules with disparate functional groups (for example, natural products) is a long-standing challenge that has been addressed using catalysts tuned to perform singular transformations (for example, C-H hydroxylation). A method whereby reactions with diverse functional groups within a single natural product are feasible depending on which catalyst or reagent is chosen would widen the possible structures one could obtain. Fluoroarylborane catalysts can heterolytically split Si-H bonds to yield an oxophilic silylium (R3Si+) equivalent along with a reducing (H-) equivalent...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256499/predicting-dna-hybridization-kinetics-from-sequence
#12
Jinny X Zhang, John Z Fang, Wei Duan, Lucia R Wu, Angela W Zhang, Neil Dalchau, Boyan Yordanov, Rasmus Petersen, Andrew Phillips, David Yu Zhang
Hybridization is a key molecular process in biology and biotechnology, but so far there is no predictive model for accurately determining hybridization rate constants based on sequence information. Here, we report a weighted neighbour voting (WNV) prediction algorithm, in which the hybridization rate constant of an unknown sequence is predicted based on similarity reactions with known rate constants. To construct this algorithm we first performed 210 fluorescence kinetics experiments to observe the hybridization kinetics of 100 different DNA target and probe pairs (36 nt sub-sequences of the CYCS and VEGF genes) at temperatures ranging from 28 to 55 °C...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256498/self-assembly-of-polyhedral-metal-organic-framework-particles-into-three-dimensional-ordered-superstructures
#13
Civan Avci, Inhar Imaz, Arnau Carné-Sánchez, Jose Angel Pariente, Nikos Tasios, Javier Pérez-Carvajal, Maria Isabel Alonso, Alvaro Blanco, Marjolein Dijkstra, Cefe López, Daniel Maspoch
Self-assembly of particles into long-range, three-dimensional, ordered superstructures is crucial for the design of a variety of materials, including plasmonic sensing materials, energy or gas storage systems, catalysts and photonic crystals. Here, we have combined experimental and simulation data to show that truncated rhombic dodecahedral particles of the metal-organic framework (MOF) ZIF-8 can self-assemble into millimetre-sized superstructures with an underlying three-dimensional rhombohedral lattice that behave as photonic crystals...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256497/polyoxometalate-electrocatalysts-based-on-earth-abundant-metals-for-efficient-water-oxidation-in-acidic-media
#14
Marta Blasco-Ahicart, Joaquín Soriano-López, Jorge J Carbó, Josep M Poblet, J R Galan-Mascaros
Water splitting is a promising approach to the efficient and cost-effective production of renewable fuels, but water oxidation remains a bottleneck in its technological development because it largely relies on noble-metal catalysts. Although inexpensive transition-metal oxides are competitive water oxidation catalysts in alkaline media, they cannot compete with noble metals in acidic media, in which hydrogen production is easier and faster. Here, we report a water oxidation catalyst based on earth-abundant metals that performs well in acidic conditions...
January 2018: Nature Chemistry
https://www.readbyqxmd.com/read/29256517/terbium-glows-green
#15
Geng Deng
No abstract text is available yet for this article.
December 19, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/29256516/making-molecular-monsters
#16
Michelle Francl
No abstract text is available yet for this article.
December 19, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/29256514/collaborative-routes-to-clarifying-the-murky-waters-of-aqueous-supramolecular-chemistry
#17
REVIEW
Paul S Cremer, Amar H Flood, Bruce C Gibb, David L Mobley
On planet Earth, water is everywhere: the majority of the surface is covered with it; it is a key component of all life; its vapour and droplets fill the lower atmosphere; and even rocks contain it and undergo geomorphological changes because of it. A community of physical scientists largely drives studies of the chemistry of water and aqueous solutions, with expertise in biochemistry, spectroscopy and computer modelling. More recently, however, supramolecular chemists - with their expertise in macrocyclic synthesis and measuring supramolecular interactions - have renewed their interest in water-mediated non-covalent interactions...
December 19, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/29256513/correction
#18
(no author information available yet)
This corrects the article DOI: 10.1038/nchem.2895.
December 19, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/29256507/flexible-molecular-materials-stressed-out-crystals
#19
Bart Kahr, Michael D Ward
No abstract text is available yet for this article.
December 19, 2017: Nature Chemistry
https://www.readbyqxmd.com/read/29256502/erratum-glucose-responsive-insulin-by-molecular-and-physical-design
#20
Naveed A Bakh, Abel B Cortinas, Michael A Weiss, Robert S Langer, Daniel G Anderson, Zhen Gu, Sanjoy Dutta, Michael S Strano
This corrects the article DOI: 10.1038/nchem.2857.
December 19, 2017: Nature Chemistry
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