Archive for the ‘Hot Articles’ Category

HOT Chemical Science articles for January

We are happy to present a selection of our HOT articles for January. To see all of our HOT referee-recommended articles from 2019, please find the collection here.

As always, Chemical Science articles are free to access.

Enantioselective [1,3] O-to-C rearrangement: dearomatization of alkyl 2-allyloxy/benzyloxy-1/3-naphthoates catalyzed by a chiral π–Cu(II) complex

Lu Yao, Kazuaki Ishihara*

Chem. Sci., 2019, 10, 2259-2263

DOI
: 10.1039/C8SC05601C, Edge Article

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Through-space charge transfer hexaarylbenzene dendrimers with thermally activated delayed fluorescence and aggregation-induced emission for efficient solution-processed OLEDs

Xingdong Wang, Shumeng Wang, Jianhong Lv, Shiyang Shao,* Lixiang Wang,* Xiabin Jing and Fosong Wang

Chem. Sci., 2019, Advance Article

DOI
: 10.1039/C8SC04991B, Edge Article

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Heterolytic bond activation at gold: evidence for gold(III) H–B, H–Si complexes, H–H and H–C cleavage

Luca Rocchigiani,* Peter H. M. Budzelaar* and Manfred Bochmann*

Chem. Sci., 2019, 10, 2633-2642

DOI
: 10.1039/C8SC05229H, Edge Article

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Insights into mechanochemical reactions at the molecular level: simulated indentations of aspirin and meloxicam crystals

Michael Ferguson, M. Silvina Moyano, Gareth A. Tribello, Deborah E. Crawford, Eduardo M. Bringa, Stuart L. James,* Jorge Kohanoff* and Mario G. Del Pópolo*

Chem. Sci., 2019, Advance Article

DOI
: 10.1039/C8SC04971H, Edge Article

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Structure revision of cryptosporioptides and determination of the genetic basis for dimeric xanthone biosynthesis in fungi

Claudio Greco, Kate de Mattos-Shipley, Andrew M. Bailey, Nicholas P. Mulholland, Jason L. Vincent, Christine L. Willis, Russell J. Cox* and Thomas J. Simpson*

Chem. Sci., 2019, Advance Article

DOI
: 10.1039/C8SC05126G, Edge Article

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From nano-balls to nano-bowls

Helena Brake, Eugenia Peresypkina, Claudia Heindl, Alexander V. Virovets, Werner Kremer and Manfred Scheer*

Chem. Sci., 2019, Advance Article

DOI
: 10.1039/C8SC05471A, Edge Article

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Learning from Nature: A Cu(II)-Porphyrin Complex Produces Oxygen Gas from Water at Ultra-Small Overpotential

Sunlight-assisted water splitting represents a sustainable way to convert solar energy into chemical energy in hydrogen and oxygen gases. Due to its high activation energy, the oxygen evolution reaction (OER) requires large overpotential for initiation. Developing suitable OER catalysts to reduce the overpotential thus becomes instrumental for the feasibility of solar energy harvesting.

Recently, a group of scientists led by Rui Cao from Renmin University of China, and Shaanxi Normal University, China, has developed a water-soluble Cu(II)-porphyrin complex as a high-performance OER catalyst. This breakthrough has been published in Chemical Science (DOI: 10.1039/C8SC04529A).

Inspired by the molecular structure of a natural OER catalyst in the photosynthesis system – photosystem II (PSII), the researchers designed a Cu2+-coordination compound with a porphyrin ligand, tetrakis(4-N-methylpyridyl)porphyrin (Figure 1a), which mimics the structure of PSII. This biomimetic Cu2+-complex exhibits outstanding catalytic OER activity in a phosphate buffer solution at pH=7.0. The current of the cyclic voltammogram of the Cu2+-complex increases sharply (due to O2 evolution) at an onset potential of 1.13 V vs. normal hydrogen electrode (Figure 1b), corresponding to an OER overpotential of 310 mV. For comparison, the cyclic voltammograms of a blank buffer solution and a CuSO4-containing buffer solution show no pronounced current enhancement (Figure 1b), indicating the electrolyte itself and the un-coordinated Cu2+ cannot generate O2 within the tested potential range. The 310 mV overpotential is approximately two times smaller than the typical values exhibited by previously reported Cu complexes.

Figure 1. (a) The molecular structure of Cu2+-tetrakis(4-N-methylpyridyl)porphyrin complex. (b) Cyclic voltammograms of 1 mM Cu2+-tetrakis(4-N-methylpyridyl)porphyrin (red), bare buffer solution (black) and buffer solution containing 1 mM CuSO4 (green). The electrode is a piece of fluorine-doped tin oxide glass slide.

The authors ascribed the ultra-small OER overpotential to the formation of an oxidized form of the Cu2+-porphyrin complex. This oxidized species is generated after the complex loses one electron, and is active for O-O bond formation and subsequent O2 evolution. The energy barrier of this one-electron-oxidation pathway is expected to be much lower than those of conventional processes involving higher-valent Cu species (e.g., Cu4+-oxo), which facilitates OER at small overpotential.

With the complete catalytic cycle of water oxidation by the Cu2+-porphyrin complex being fully revealed, OER will become more efficient and energy-saving.

To find out more please read:

Low Overpotential Water Oxidation at Neutral pH Catalyzed by A Copper(II) Porphyrin

Yanju Liu, Yongzhen Han, Zongyao Zhang, Wei Zhang, Wenzhen Lai, Yong Wang and Rui Cao

Chem. Sci., 2019, DOI: 10.1039/C8SC04529A

About the blogger:

Tianyu Liu obtained his Ph.D. (2017) in Chemistry from University of California, Santa Cruz in the United States. He is passionate about scientific communication to introduce cutting-edge research to both the general public and scientists with diverse research expertise. He is a blog writer for Chem. Commun. and Chem. Sci. More information about him can be found at http://liutianyuresearch.weebly.com/.

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HOT Chemical Science articles for December

We are happy to present a selection of our HOT articles over the past month. To see all of our HOT referee-recommended articles from 2018, please find the collection here.

As always, Chemical Science articles are free to access.

Reaction-free and MMP-independent fluorescent probes for long-term mitochondria visualization and tracking

Ruoyao Zhang, Guangle Niu, Xuechen Li, Lifang Guo, Huamiao Zhang, Rui Yang, Yuncong Chen, Xiaoqiang Yu and Ben Zhong Tang

Chem. Sci., 2019, Advance Article

DOI: 10.1039/C8SC05119D, Edge Article

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Monitoring metal–amyloid-β complexation by a FRET-based probe: design, detection, and inhibitor screening

Hyuck Jin Lee, Young Geun Lee, Juhye Kang, Seung Hyun Yang, Ju Hwan Kim, Amar B.T. Ghisaidoobe, Hyo Jin Kang, Sang-Rae Lee, Mi Hee Lim and Sang J. Chung

Chem. Sci., 2019, Accepted Manuscript

DOI: 10.1039/C8SC04943B, Edge Article

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Fluorinated synthetic anion carriers: experimental and computational insights into membrane partitioning and transmembrane chloride transport mechanism

Michael J. Spooner, Hongyu Li, Igor Marques, Pedro M. R. Costa, Xin Wu, Ethan N. W. Howe, Nathalie Busschaert, Stephen J. Moore, Mark E. Light, David N. Sheppard, Vítor Félix and Philip A. Gale

Chem. Sci., 2019, Accepted Manuscript

DOI: 10.1039/C8SC05155K, Edge Article

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How machine learning can assist the interpretation of ab initio molecular dynamics simulations and conceptual understanding of chemistry

Florian Häse, Ignacio Fdez. Galván, Alán Aspuru-Guzik, Roland Lindh and Morgane Vacher

Chem. Sci., 2019, Accepted Manuscript

DOI: 10.1039/C8SC04516J, Edge Article

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Synergistic Self-Seeding in One-Dimension: a Route to Patchy and Block Comicelles with Uniform and Controllable Length

Jiangping Xu, Hang Zhou, Qing Yu, Gerald Guerin, Ian Manners and Mitchell A. Winnik

Chem. Sci., 2019, Advance Article

DOI: 10.1039/C8SC04705G, Edge Article

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Optical control of the antigen translocation by syntethic photo-conditional viral inhibitors

M. Braner, N. Koller, J. Knauer, V. Herbring, S. Hank, R. Wieneke and R. Tampé

Chem. Sci., 2019, Advance Article

DOI: 10.1039/C8SC04863K, Edge Article

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Carbon Coating Promotes CO2 Reduction on Nickel Surfaces

Reducing CO2 into fuels such as CO or hydrocarbons is a promising strategy to reduce the net emission of greenhouse gases and mitigate climate change. The CO2 reduction reaction, however, is an energy-costly process. Therefore, CO2 reduction catalysts are necessary to enhance the CO2 conversion efficiency and minimize the overall energy demand.

Researchers are developing high-performance yet inexpensive CO2 reduction catalysts. Noble metals such as Au, Ag and Pd exhibit high CO2-to-CO conversion efficiency, but their scarcity restricts their large-scale practicability. Metallic Fe, Co and Ni are active in reducing CO2 and therefore, have been identified as alternatives to the noble metal catalysts.

Recently in Chem. Sci., a group of scientists led by Zhenyu Sun from Beijing University of Chemical Technology and Yousung Jung from Korea Advanced Institute of Science and Technology (KAIST) pushed the CO2-reduction activity of Ni metal to a new height. The researchers synthesized carbon-supported Ni nanocrystals via pyrolysis of Ni-based metal organic frameworks (MOFs) in argon. The resultant Ni nanoparticles had an average diameter of ~30 nm and were embedded in N-doped carbon scaffolds (Fig. 1a). Each nanoparticle was uniformly coated with a thin layer of amorphous carbon (Fig. 1b).

Figure 1. (a) The elemental mapping of the carbon-supported Ni nanoparticles. Green dots and blue regions are Ni nanoparticles and carbon matrices, respectively. (b) The scanning transmission electron microscope image showing the thin carbon coating on a Ni nanoparticle surface. (c) The CO2-to-CO conversion efficiencies at different applied potentials. Ni-NC_ATPA@C and Ni-NC_TPA@C are carbon-supported Ni nanoparticles derived from MOFs with 2-amino-terephthalic acid and terephthalic acid organic linkers, respectively. NC_ATPA@C is the Ni-free carbon powder derived from ATPA.

The CO2-to-CO conversion efficiencies of these Ni-C nanocomposites were the highest among all the reported carbon-supported Ni nanoparticles. The best Ni catalyst achieved a maximal efficiency of ~94% at an overpotential of 0.59 V, while previously reported Ni-C catalysts typically exhibited efficiencies lower than 25%. The significantly improved conversion efficiency was associated with the thin carbon coating. This coating prevented the Ni nanoparticles from directly contacting with aqueous electrolytes, and thus minimized hydrogen evolution reaction, a side reaction that decreased the conversion efficiency.

This work highlights the instrumental role of the surface carbon layers in promoting the CO2-reduction activity of Ni nanoparticles. The carbon-coating strategy could be extended to other low-cost transition metals, which may lead to a variety of cost-effective CO2-reduction catalysts.

 

To find out more please read:

Carbon-Supported Ni Nanoparticles for Efficient CO2 Electroreduction

Mingwen Jia, Changhyeok Choi, Tai-Sing Wu, Chen Ma, Peng Kang, Hengcong Tao, Qun Fan, Song Hong, Shizhen Liu, Yun-Liang Soo, Yousung Jung, Jieshan Qiu and Zhenyu Sun

Chem. Sci., 2018, 9, 8775-8780

 

About the blogger:

Tianyu Liu obtained his Ph.D. (2017) in Chemistry from University of California, Santa Cruz in the United States. He is passionate about scientific communication to introduce cutting-edge research to both the general public and scientists with diverse research expertise. He is a blog writer for Chem. Commun. and Chem. Sci. More information about him can be found at http://liutianyuresearch.weebly.com/.

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HOT Chemical Science articles for November

We are happy to present a selection of our HOT articles over the past month. To see all of our HOT referee-recommended articles from 2018, please find the collection here.

As always, Chemical Science articles are free to access.

Carbon-supported Ni nanoparticles for efficient CO2 electroreduction

Mingwen Jia, Changhyeok Choi, Tai-Sing Wu, Chen Ma, Peng Kang, Hengcong Tao, Qun Fan, Song Hong, Shizhen Liu, Yun-Liang Soo, Yousung Jung, Jieshan Qiu and Zhenyu Sun

Chem. Sci., 2018, Advance Article

DOI: 10.1039/C8SC03732A, Edge Article

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Rare “Janus”-Faced {FeII7} Single-Molecule Magnet Exhibiting Intramolecular Ferromagnetic Interactions

Dimitris I Alexandropoulos, Kuduva R. Vignesh, Theocharis Stamatatos and Kim R. Dunbar

Chem. Sci., 2019, Accepted Manuscript

DOI: 10.1039/C8SC04384A, Edge Article

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Lytic Reactions of Drugs with Lipid Membranes

Hannah Mary Britt, Clara Antia García-Herrero, Paul W Denny, Jackie A. Mosely and John M Sanderson

Chem. Sci., 2019, Accepted Manuscript

DOI: 10.1039/C8SC04831B, Edge Article

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A Catalytic Antioxidant for Limiting Amyloid-Beta Peptide Aggregation and Reactive Oxygen Species Generation

Luiza M. F. Gomes, Atif Mahammed, Kathleen E Prosser, Jason R. Smith, Michael A. Silverman, Charles John Walsby, Zeev Gross and Tim Storr

Chem. Sci., 2019, Accepted Manuscript

DOI: 10.1039/C8SC04660C, Edge Article

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A bio-inspired approach to ligand design: folding single-chain peptoids to chelate a multimetallic cluster

Andy I. Nguyen, Ryan K. Spencer, Christopher L. Anderson and Ronald N. Zuckermann

Chem. Sci., 2018, Advance Article

DOI: 10.1039/C8SC04240C, Edge Article

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Single Ru atoms with precise coordination on a monolayer layered double hydroxide for efficient electrooxidation catalysis

Zelin Wang, Si-Min Xu, Yanqi Xu, Ling Tan, Xian Wang, Yufei Zhao, Haohong Duan and Yu-Fei Song

Chem. Sci., 2019, Advance Article

DOI: 10.1039/C8SC04480E, Edge Article

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Mutant Enzymes and Frankenstein Catalysts

I know what you’re thinking: “Autumn is here! Who needs sunny weather and optimism? Sign me up for grey skies and vitamin D supplements!”. Oh you weren’t thinking that? Me neither. Well perhaps Halloween gives you more joy, along with the chance to see one of your colleagues dressed up like Freddy Mercury (‘Hg’ emblazoned on their chest, classic) at the departmental party?

In the spirit of Halloween, Simone Morra and Anca Pordea at the University of Nottingham have synthesized a mutant alcohol dehydrogenase enzyme turned Frankenstein catalyst, by replacing the zinc catalytic site with a covalently-bound rhodium(III) complex. The resulting mutant/transition-metal composite was used in combination with the wild-type enzyme to synthesize the chiral alcohol (S)-4-phenyl-2-butanol.

Like many hybrid systems, the purpose of combining enzymatic with transition metal catalysis is to take advantage of the benefits of each. Millions of years of evolution have produced enzymatic catalysts that function under mild conditions, in aqueous solvents, with impressive selectivity and high catalytic efficiency. But the narrow range of conditions that enzymes operate under can be disadvantageous in a synthetic setting. On the other hand, transition metal catalysts are versatile and can be easily customised, reacting with a liberty that would make the most promiscuous of enzymes blush.

Unfortunately, developing multi-component systems that utilise both transition metal and enzymatic catalysis is not as simple as combining them in a single mixture, as mutual deactivation often results. The authors found that encasing the transition metal complex in an enzyme provided a physical shield against inhibition, and preserved the activity of both the wild type enzyme and the rhodium(III) complex.

Synthesis of chiral alcohols via two interconnected cycles: the wild type enzyme (native ADH) reduces the ketone to the alcohol using NADPH as a reducing agent. NADPH is regenerated using the mutant enzyme containing a rhodium active site (chemically modified ADH) with formic acid as the terminal reductant. Alcohol dehydrogenase

Synthesis of chiral alcohols via two interconnected cycles: the wild type enzyme (native ADH) reduces the ketone using NADPH as a reducing agent. NADPH is regenerated by the mutant enzyme containing a catalytically-active rhodium complex (chemically modified ADH) with formic acid as the terminal reductant.

Two interconnected catalytic cycles were responsible for synthesis of the chiral alcohol. In the first, the wild type enzyme effected reduction of 4-phenyl-2-butanol, a process that relies on the biological reductant nicotinamide adenine dinucleotide phosphate (NADPH). In the second cycle, NADPH was recycled using the composite rhodium(III) complex/mutant enzyme, with formic acid as the stoichiometric reductant. The rate of alcohol formation was slow (turnover frequency of 0.02 s-1) and the transition-metal catalysed process was deemed to be rate limiting (compare to turnover frequencies of 4.8 s-1 for enzymatic systems). However, near perfect enantioselectivity was obtained (>99% ee).

This research demonstrates one way that transition metal catalysts can augment the scope of co-factor-dependent enzymes. Furthermore, devising strategies to prepare metal-complex/enzyme bioconjugates might have value for small molecule synthesis due to the second coordination sphere that enzymes offer; an encased steric environment to guide the reaction outcome is a valuable approach to improving selectivity in catalytic reactions.

To find out more please read:

Biocatalyst-artifical metalloenzyme cascade based on alcohol dehydrogenase

Simone Morra, Anca Pordea.
Chem. Sci., 2018, 9, 7447-7454
DOI: 10.1039/c8sc02371a

About the author

Zoë Hearne is a PhD candidate in chemistry at McGill University in Montréal, Canada, under the supervision of Professor Chao-Jun Li. She hails from Canberra, Australia, where she completed her undergraduate degree. Her current research focuses on transition metal catalysis to effect novel transformations, and out of the lab she is an enthusiastic chemistry tutor and science communicator.

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HOT Chemical Science articles for July

We are happy to present a selection of our HOT articles over the past month. To see all of our HOT referee-recommended articles from 2018, please find the collection here.

As always, Chemical Science articles are free to access.

Disarming the virulence arsenal of Pseudomonas aeruginosa by blocking two-component system signalling
Manibarsha Goswami, Adeline Espinasse and Erin E. Carlson
Chem. Sci., 2018, Advance Article
DOI: 10.1039/C8SC02496K, Edge ArticleDisarming the virulence arsenal of Pseudomonas aeruginosa by blocking two-component system signaling; 10.1039/C8SC02496K; Manibarsha Goswami, Adeline Espinassea and Erin E. Carlson

 

Dynamically imaging collision electrochemistry of single electrochemiluminescence nano-emitters
Cheng Ma, Wanwan Wu, Lingling Li, Shaojun Wu, Jianrong Zhang, Zixuan Chen and Jun-Jie Zhu
Chem. Sci., 2018,9, 6167-6175
DOI: 10.1039/C8SC02251H, Edge Article

Dynamically imaging collision electrochemistry of single electrochemiluminescence nano-emitters; 10.1039/C8SC02251H; Cheng Ma, Wanwan Wu, Lingling Li, Shaojun Wu, Jianrong Zhang, Zixuan Chen and Jun-Jie Zhu

 

Replacing H+ by Na+ or K+ in phosphopeptide anions and cations prevents electron capture dissociation
Eva-Maria Schneeberger and Kathrin Breuker
Chem. Sci., 2018, Advance Article
DOI: 10.1039/C8SC02470G, Edge Article

Replacing H+ by Na+ or K+ in phosphopeptide anions and cations prevents electron capture dissociation; 10.1039/C8SC02470G; Eva-Maria Schneeberger and Kathrin Breuker

 

Reversible coordination of N2 and H2 to a homoleptic S = 1/2 Fe(I) diphosphine complex in solution and the solid state
Laurence R. Doyle, Daniel J. Scott, Peter J. Hill, Duncan A. X. Fraser, William K. Myers, Andrew J. P. White, Jennifer C. Green and Andrew E. Ashley
Chem. Sci., 2018, Advance Article
DOI: 10.1039/C8SC01841C, Edge Article

Reversible coordination of N2 and H2 to a homoleptic S = 1/2 Fe(I) diphosphine complex in solution and the solid state; 10.1039/C8SC01841C; Laurence R. Doyle, Daniel J. Scott, Peter J. Hill, Duncan A. X. Fraser, William K. Myers, Andrew J. P. White, Jennifer C. Green and Andrew E. Ashley

 

Unraveling reaction networks behind the catalytic oxidation of methane with H2O2 over a mixed-metal MIL-53(Al,Fe) MOF catalyst
Ágnes Szécsényi, Guanna Li, Jorge Gascon and Evgeny A. Pidko
Chem. Sci., 2018, Advance Article
DOI: 10.1039/C8SC02376J, Edge Article

Unraveling reaction networks behind the catalytic oxidation of methane with H2O2 over a mixed-metal MIL-53(Al,Fe) MOF catalyst; 10.1039/C8SC02376J; Ágnes Szécsényi, Guanna Li Jorge Gascon and Evgeny A. Pidko

 

Multi-omics and temporal dynamics profiling reveal disruption of central metabolism in Helicobacter pylori on bismuth treatment
Bingjie Han, Zhen Zhang, Yanxuan Xie, Xuqiao Hu, Haibo Wang, Wei Xia, Yulan Wang, Hongyan Li, Yuchuan Wang and Hongzhe Sun
Chem. Sci., 2018, Advance Article
DOI: 10.1039/C8SC01668B, Edge Article

Multi-omics and temporal dynamics profiling reveal disruption of central metabolism in Helicobacter pylori on bismuth treatment; 10.1039/C8SC01668B; Bingjie Han, Zhen Zhang, Yanxuan Xie, Xuqiao Hu, Haibo Wang, Wei Xia, Yulan Wang, Hongyan Li, Yuchuan Wang and Hongzhe Sun

 

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Gaunt Lab and the Holy Grail: Synthesis of Lactams via C-H Activation

A small consolation when marking undergraduate organic chemistry exams is that occasionally you come across an answer so ridiculous it is almost brilliant. Penned to complete a far-fetched synthesis, the student managed to propose a reaction that is completely without precedent, not only in the course, but in the chemistry literature as a whole. Sadly for the student it is completely wrong, 0 marks.

I imagine that 50 years ago if an undergraduate student had proposed a one-step synthesis of γ-lactams starting with a linear alkylamine, which proceeded by clipping off an N-H bond and a C-H bond, then stitching it together with a carbon monoxide molecule at the junction, they too may have got 0 marks. Yet Matthew Gaunt and researchers in his laboratory at the University of Cambridge have achieved just this via palladium-catalysed C-H activation.

Transition metal-catalysed C-H activation refers to the cleavage of a C-H bond by a transition metal, followed by functionalisation of the metal-bound organic fragment and regeneration of the catalyst. This strategy is counter to the classical approach of organic synthesis: construction of molecular complexity by installing and manipulating reactive functional groups. The object of pre-functionalisation is two-fold: it makes a molecule more reactive (for example, installation of a halide can enable oxidative addition to a transition metal or substitution by a nucleophile) and it directs reactivity to a specific location in the molecule under construction. For C-H activation the challenge is to promote reaction of thermodynamically and kinetically stable C-H bonds, and achieve site-selectivity in a molecule containing many chemically-similar C-H bonds.

Figure 1: Optimised reaction conditions and selected products of the C-H activation of linear alkylamines for the synthesis of lactams by palladium catalyzed C-H activation

Figure 1: Optimised reaction conditions

The authors found that a catalytic system consisting of palladium pivalate and copper acetate, in combination with acidic and basic additives under a CO/air atmosphere, transformed a variety of secondary amines with primary C-H bonds at the γ-position into 5-membered lactones (Figure 1). Good yields and diastereoselectivities were obtained, and a variety of substituents such as carbocycles, tetrahydropyran, piperadine, fluorocycloalkanes and dioxolanes were well tolerated.

Figure 2: Mechanistic hypothesis illustrating: C-H activation step, H-bond between the amine and pivalate, intramolecular base-assisted deprotonation, and preference for formation of the trans diastereomer.

Figure 2: Mechanistic hypothesis showing organisation of the transition state and C-H activation.

The reacting components in the C-H activation step are highly organised in the transition state by coordination of the amine to the palladium centre, and formation of a hydrogen bond between the amine and the carbonyl group of a pivalate ligand bound to palladium (Figure 2). Palladium insertion into the C-H bond (one of the pivalate ligands serves as an intramolecular base) forms a palladacycle with the entropic and enthalpic preference for a 5-membered ring, necessitating abstraction of a proton in the γ-position with respect to the amine directing group.

C-H activation has been referred to as the ‘holy grail’ of catalysis, and the efficiency gains are clear: reduction in reaction steps and use of catalysis minimises energy use, formation of stoichiometric by-products and waste from isolation and purification processes, excess reagents, solvents and additives. This aside, the most exciting thing about the development of C-H activation methods is the promise of discovery: novel reactivity can lead to novel products, inaccessible by other means.

 

 

To find out more please read:

Diastereoselective C-H carbonylative annulation of aliphatic amines: a rapid route to functionalized γ-lactams

Png Zhuang Mao, Jaime R. Cabrera-Pardo, Jorge Piero Cadahia and Matthew J. Gaunt.
Chem. Sci., 2018, Edge Article
DOI: 10.1039/c8sc02855a

About the author

Zoë Hearne is a PhD candidate in chemistry at McGill University in Montréal, Canada, under the supervision of Professor Chao-Jun Li. She hails from Canberra, Australia, where she completed her undergraduate degree. Her current research focuses on transition metal catalysis to effect novel transformations, and out of the lab she is an enthusiastic chemistry tutor and science communicator.

 

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Don’t rely on a gut feeling: investigating microbiota/human co-metabolism

A new trend gripping popular science (and business) is personal DNA testing. A host of companies sell the idea that your genetic heritage distinguishes you, and reveals who you really are. Do you really want to know what you are on a molecular level? If it’s a numbers game, you are mostly bacterial (that’s why you’re so cultured!). Bacteria outnumber our body’s cells 1.3:1. The majority of bacteria reside in the gastrointestinal tract, contributing to a microbiota of archea, eukaryotes and viruses that have a commensal relationship with the human body.

The microbiota has been linked to many vital physiological pathways including human nutrition (harvesting further energy and nutrients), immunity, inflammation and the detoxification of xenobiotic substances. Conversely, dysregulation of such pathways has been associated with diseases such as diabetes, cancer, inflammatory bowel syndrome and cardiovascular disease. Due to the number of pathways involved, it is hoped that studying the microbiota may identify enzyme targets for therapeutics or biomarkers for disease.

However, understanding of these pathways is limited, and research progress relies on advances in analytical tools. Headed by Dr Daniel Globisch at Uppsala University in Sweden, researchers have developed an analytical method to identify O-sulphated metabolites. Microbes are capable of a suite of metabolic reactions that complement the capabilities of human enzymes, and O-sulphate functionalization is characteristic of microbe/human co-metabolism as it can be catalysed by bacterial sulphotransferase enzymes.

O-sulfate functionalised molecules can be selectively analysed using sulphatase sulfatase treatment and UPLC-MS/MS

O-sulphate functionalised molecules can be selectively analysed using sulphatase treatment and UPLC-MS/MS

The researchers developed an assay to identify O-sulphated compounds in urine and faecal samples. The assay was designed using a sulphatase enzyme capable of hydrolysing the oxygen-sulfur bond in a wide variety of arylsulphate molecules. Samples were treated with this enzyme and the resulting mixtures were analysed by UPLC-MS/MS (ultra performance liquid chromatography/tandem mass spectrometry). Results were compared with the data output of control samples without enzymatic treatment and features in the spectra with a mass change of 79.9568 m/z (loss of the sulfate group) were identified, leading to the identification of 206 O-sulphated metabolites. This is a notable result as it triples the number of sulphated metabolites currently recorded in the human metabolome database.

A number of interesting compounds were identified: ferulic acid is a metabolite produced by the microbiota thought to prevent thrombosis and artherosclerosis, and indoxyl sulfate and p-cresylsulfate are biomarkers of chronic kidney disease and cardiovascular disease, respectively. Mentioned are three molecules of the 206 uncovered, giving a glimpse of the applications that further research, armed with the right analytical tools, might discover.

To find out more please read:

New enzymatic and mass spectrometric methodology for the selective investigation of gut microbiota-derived metabolites

Caroline Ballet, Mário S. P. Correia, Louis P. Conway, Theresa L. Locher, Laura C. Lehmann, Neeraj Garg, Miroslav Vujasinović, Sebastian Deindl, J.-Matthias Löhr, Daniel Globisch.
Chem. Sci., 2018, Advance Article
DOI: 10.1039/c8sc01502c

About the author

Zoë Hearne is a PhD candidate in chemistry at McGill University in Montréal, Canada, under the supervision of Professor Chao-Jun Li. She hails from Canberra, Australia, where she completed her undergraduate degree. Her current research focuses on transition metal catalysis to effect novel transformations, and out of the lab she is an enthusiastic chemistry tutor and science communicator.

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How Can We Stabilize Bismuth in Potassium-Ion Batteries? Add Salts!

The large-scale manufacturing and widespread demand of consumer electronics in modern societies call for batteries with affordable prices. Potassium-ion batteries are one of the economical alternatives to lithium-ion batteries, as the cost of potassium is much lower than lithium. However, these types of batteries have yet to be commercially available, partly due to the lack of high-performance and stable anode materials. Bismuth (Bi) is a promising anode material for potassium-ion batteries, because of its substantially higher theoretical charge-storage capacity than the conventional ones. Unfortunately, its poor durability severely hinders the applicability.

Now the drawback of Bi has been successfully addressed by increasing the electrolyte concentration. This breakthrough, demonstrated by Chuan-Fu Sun and coworkers from Chinese Academy of Sciences, China, was recently published in Chemical Science.

Sun and coworkers investigated the interplay between the electrolyte concentration and the charge-storage performance stability of Bi nanoparticles (Figure 1a). They identified the optimal concentration of the solute, potassium bis(tri-fluoromethylsulfonyl)imide, to be 5 M. Under this condition, the irreversible electrolyte reduction reaction on the Bi surface experienced the highest resistance. Impeding this unwanted reaction thus elongated the lifespan of Bi electrodes. In addition, the concentrated electrolyte resulted in thin layers of the reduction products being deposited on the Bi surface. This allowed ions in the electrolyte to easily penetrate the surface coatings and interact with the encapsulated Bi nanoparticles, maintaining the intrinsically high capacity of Bi (Figure 1b). Other concentrations either led to rapid battery failure or significantly reduced capacity.

Figure 1. (a) A scanning electron microscopy image of the Bi nanoparticles. (b) The change of the Bi electrode capacity vs. charge-discharge cycle number with different electrolyte concentrations. CE: coulombic efficiency.

This work innovates the design and development of commercially viable potassium-ion batteries. The strategy of increasing the electrolyte concentration could possibly be adapted to solve electrode instability issues associated with other rechargeable batteries.

 

To find out more please read:

Concentrated Electrolytes Stabilize Bismuth-Potassium Batteries

Ruding Zhang, Jingze Bao, Yu-Huang Wang and Chuan-Fu Sun

Chem. Sci., 2018, DOI: 10.1039/c8sc01848k

 

About the blogger:

Tianyu Liu obtained his Ph.D. (2017) in Physical Chemistry from University of California, Santa Cruz in the United States. He is passionate about scientific communication to introduce cutting-edge research to both the general public and scientists with diverse research expertise. He is a blog writer for Chem. Commun. and Chem. Sci. More information about him can be found at http://liutianyuresearch.weebly.com/.

 

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