Archive for the ‘News’ Category

Telescope arrangement puts a twist on organic synthesis

Scientists have adapted a technique more commonly used for making crisps and mixing polymers so that it can perform complex multi-component organic reactions in a single step without the need for a solvent.

Source: Royal Society of Chemistry, Laboratory-scale twin screw extruder

Fine chemicals such as drugs, food additives and fragrances are typically made through complex processes with many intricate reaction steps. These steps can be time-consuming and expensive, and often require solvents that are harmful to the environment. But mechanochemistry, where mechanical forces initiate chemical reactions, could side-step such problems.

Read the full story by Thomas Foley on Chemistry World.

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Negative press is not always a bad thing: a novel anode material for sodium-ion batteries

At a product launch in California last week Elon Musk introduced Tesla’s new electric semi-trailer truck. Musk sells a tantalising future: one where an electric fleet replaces vehicles which currently rely on fossil fuels. Central to this fleet are powerful rechargeable batteries. Lithium-ion batteries are favoured for many current applications, such as portable electronic devices and the current offerings of full and hybrid vehicles. In coming years they are projected to be the technology of choice for the large-scale applications mentioned above and for storing power generated from intermittent renewable energy sources.

A limiting factor in the widespread roll-out of lithium batteries is that lithium is an expensive resource with low natural abundance. Sodium offers a possible alternative and has the obvious benefits of being both very cheap, and one of the most abundant elements in the earth’s crust. The electrode materials used in lithium batteries cannot be used to make the sodium variant because the sodium ion is larger (1.02 Å compared to 0.76 Å for lithium) and damages the crystalline materials optimised for lithium.

Researchers Gu, Gu and Yang at Beihang University in Beijing have reported the synthesis and performance of a novel anode material optimised for sodium. The material is a graphene-tetrahydroxybenzoquinone (Na4C6O6) hybrid, and is comprised of a porous graphene-oxide scaffold decorated with nanocrystals of Na4C6O6. Furthermore, X-ray photoelectron spectroscopy (XPS) reveals the homogenous distribution of sodium throughout this conducting material.

The electrochemical performance contrasts with previously reported materials of this type by exhibiting high cyclic stability. The reversible capacity of graphene-Na4C6O6 at a current density of 74.4 mA g-1 is 268 mA h g-1, a value which is steady over 60 cycles. This is competitive with the graphite anode materials found in lithium batteries, which have specific capacities between 200 and 400 mA h g-1. Furthermore the material performs well over a range of current densities, with reversible capacities of 95 – 211 mA h g-1 measured over a range of 3720 – 186 mA g-1.

With this work the authors contribute, at most, a viable candidate for the next rechargeable sodium battery and, at the very least, continued research into sustainable technologies. This ensures that in addressing our current energy challenges we are solving the problem, not delaying it.

To find out more please read:

3D organic Na4C6O6/graphene architecture for fast sodium storage with ultralong cycle life
Jianan Gu, Yue Gua and Shubin Yang
Chem. Commun., 2017, Advance Article
DOI: 10.1039/C7CC08045J, Communication

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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Inorganic polystyrene gives old material a new backbone

Synthetic organic polymers and plastics revolutionised the 20th century and helped shape modern-day society. But a new range of materials with useful properties could be in the pipeline thanks to a catalytic method for making ‘inorganic polystyrene’.

Source: Royal Society of Chemistry
B-arylated polyaminoboranes prepared via catalytic dehydropolymerisation

Polystyrene is an important material in today’s society with its uses ranging from a protective packaging material through to disposable cutlery. Its chemical structure, like the majority of other important synthetic polymeric materials, has a backbone of carbon atoms. To discover new materials with useful properties, researchers have tried to replicate these structures using inorganic chains, with silicone materials being a recent example. Now, Ian Manners and his team from the University of Bristol, UK, have made inorganic polymers out of boron and nitrogen.

Read the full story by Jeremy Allen on Chemistry World.

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Carbohydrates promoted in new prebiotic theory

It’s plausible that carbohydrates formed on primordial Earth before amino acids. So say UK researchers who have shown that parent molecules to amino acids can catalyse the formation of 2-deoxy-D-ribose, a sugar found in the backbone of DNA.1

Source: Royal Society of Chemistry Amino nitriles can promote the enantioselective aldol reaction of formaldehyde and glycolaldehyde to yield D-glyceraldehyde, and the subsequent reaction of the D-glyceraldehyde with acetaldehyde to make 2-deoxy-D-ribose

We’ll never know the exact process that turned chemistry into biology, but many researchers want to get as close as they can to the truth. Paul Clarke at the University of York is one of those researchers.

Read the full story by Jennifer Newton on Chemistry World.

1 A M Steer et al, Chem. Commun., 2017, DOI: 10.1039/c7cc06083a (This paper is open access.)

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Let single crystals do the heavy lifting

Researchers in the US have developed heat responsive crystalline cantilevers that are capable of lifting a metal ball almost 100 times heavier than the crystal itself.

Stimuli responsive behaviour in soft materials has blossomed in recent years, but for highly crystalline solids, such properties are still surprising, especially for materials that don’t lose their single crystalline nature in the process.

Source: Royal Society of Chemistry
Upon heating, the crystal lattice changes from herringbone packing to infinite 1D chains stacked co-facially along their π surfaces.

Jeremiah Gassensmith and colleagues at the University of Texas at Dallas and the University of North Texas, US, have developed single crystals of an N-substituted naphthalene diimide (NDI) derived organic semiconductor that can undergo a reversible phase change from its α to its β form under heating.

Read the full story by Jason Woolford on Chemistry World.

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Fluorescent test strip detects deadly phosgene gas

Chinese scientists have improved the sensitivity of test strips for phosgene gas by using a different fluorophore.

Phosgene gas reacts with lung proteins, disrupting the blood–air barrier and suffocating victims. Although deadly, many chemical plants require phosgene to synthesise products such as pharmaceuticals and pesticides. But accidental leaks are a risk. In 2016, for example, a leak at Gujarat Narmada Valley Fertilizers and Chemicals in India killed four workers and affected nine others.

Source: Royal Society of Chemistry
This is the first test-strip sensing system for gaseous phosgene made with AIE-based fluorophores

 

Read the full story by Sarah Piggott on Chemistry World.

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Automated synthesis yields sugar high

An automated synthetic method designed by chemists in Germany has assembled the longest synthetic oligosaccharide ever made from monosaccharides. The method could help to up the pace of carbohydrate research by improving researchers’ access to synthetic glycans.

Source: © Royal Society of Chemistry The researchers used automated glycan assembly to make a 50mer polymannoside

Read the full article by Jennifer Newton on Chemistry World.

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Simplified structure eases antibiotic synthesis

New analogues of the potent antibiotic teixobactin could be instrumental in the fight against multi-drug resistant pathogens.

By replacing a rare amino acid in the structure of teixobactin, UK researchers have unlocked the door to cheaper and easier-to-manufacture forms of this potent antibiotic.

(Left) Teixobactin. (Right) General structure of teixobactin analogues with the hydrophilic/charged residues shown in red, hydrophobic residues shown in black and structural differences shown in blue.

Scientists in the US reported their discovery of teixobactin in 2015. It works against multi-drug resistant pathogens, but as it contains a rare and difficult to manufacture amino acid it is hard to make.

Read the full story by Tabitha Watson on Chemistry World.

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Bismuth drug structure solved

Crystal structure of bismuth subgallate viewed along (a) [010] and (b) [100]. Bismuth, carbon and oxygen atoms are coloured purple, grey and red, respectively. Hydrogen atoms and water molecules in the pores have been omitted for clarity.

Bismuth subgallate – a widely used pharmaceutical for treating stomach ulcers – is a porous coordination polymer, new research shows. The discovery, made by scientists in Sweden and the UK, settles a long running question over the drug’s structure, which had been frustrated by bismuth subgallate’s tiny crystals and their tendency to break down when exposed to high energy electron beams.

Now, Andrew Kentaro Inge from Stockholm University and his team have overcome these issues. By combining continuous rotational data collection with a cooling technique, they avoided the electron beam damage, poor resolution and diffuse scattering holding them and others back. ‘Continuous rotation electron diffraction is a promising way to elucidate the structures of hard to obtain, or very hard to crystallise, pharmaceutical forms. For this purpose, it’s an up-and-coming method,’ says Tomislav Friŝĉić, an expert in materials chemistry at McGill University in Canada.

Read the full story by Tabitha Watson on Chemistry World.

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Siliconrhodamine Probes Enable Bio-imaging with Super-resolution

Written by Tianyu Liu, University of California, Santa Cruz

Intracellular imaging is used to reveal fine details of live organisms. It is an indispensable component for the exploration of biomolecular processes in living cells. Super-resolution microscopy (SRM) is an emerging intracellular imaging technique which can acquire images of much higher resolution than those collected by conventional optical microscopy. Currently, the greatest challenge facing SRM is to develop imaging probes that are suitable for site-specific tagging of intracellular biomolecules. Such probes must be biocompatible, membrane-permeable, intensively fluorescent and photo-stable.

Writing in ChemComm., Dr. Peter Kele and coworkers at Research Center for Natural Sciences, Hungarian Academy of Sciences have developed a group of siliconrhodamine probes that permit the labelling of intracellular proteins with excellent selectivity as well as fast response time (within 10 min).

The synthesized siliconrhodamine probes consist of a siliconrhodamine backbone anchored with a carboxyl group. The carboxyl group is responsible for the polarity-responsive property of the probes. When bound to polar protein surfaces, the probes exist in a fluorescent form. While upon non-specific binding to hydrophobic surfaces, the probes change their configurations and consequently, the fluorescence is lost. This conversion process is based on an intra-molecular Diels-Alder reaction (Figure below) that can be readily initiated by a polarity change without interrupting native biochemical processes in cells. Such a mechanism provides the probe biocompatibility and fast response characteristics.

The probe has been demonstrated for site-specific super-resolution imaging for live cells. The figure below depicts the experimental results collected using a mammalian cell. The cyan colored image (left) presents the actual cell image (as the reference). The middle magenta colored image was obtained by using one of the synthesized imaging probes. The overlay image (right) exhibits near-perfect co-localization of the reference and labelling images, indicating the probe’s excellent selectivity. Moreover, the labelling process is efficient with the probe concentration as low as 1.5 μM, and the duration as short as 10 min.

These stable, efficient, and biocompatible probes could profoundly advance super-resolution imaging of various intracellular structures.

To find out more please read:

Bioorthogonal Double-Fluorogenic Siliconrhodamine Probes for Intracellular Super-resolution Microscopy
Eszter Kozma, Gemma Estrada Girona, Giulia Paci, Edward A Lemke and Peter Kele
DOI: 10.1039/C7CC02212C

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