Archive for the ‘News’ Category

Molecular box treats chemists to a strained surprise

Introducing pillar[4]pyridinium – the first of a new family of macrocycles

Pillar[4]pyridinium
Source: Grzegorz Sobczak Oksana Danylyuk and Volodymyr Sashuk

Scientists in Poland have made the most compact multiply charged macrocycle to date. Pillar[4]pyridinium is a cyclic tetramer consisting of four pyridyl units with methylene bridges between their nitrogens and para carbons. The quadruply charged molecule has a very symmetrical and incredibly strained structure. It represents a new class of cationic macrocycles, the pillar[n]pyridiniums.

Read the full story by Jennifer Newton on Chemistry World.

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Suzuki–Miyaura–hydrogenation targets 3D drugs

Scientists in the UK have unveiled a way to make pharmaceutical molecules with increased 3D characteristics. The single pot Suzuki–Miyaura–hydrogenation reaction results in sp2–sp3 linked pharmaceutically relevant molecules.

Source: Royal Society of Chemistry
A single pot Suzuki–Miyaura-hydrogenation can be used to furnish lead and fragment-like products in good to excellent yields

The number of tetrahedral carbon atoms, or how 3D a molecule is, is one factor that determines the success of a molecule in clinical drug trials. Molecules with a high sp3 fraction are in demand, however current methods to make them suffer drawbacks. The Suzuki–Miyaura reaction is common for the cross-coupling of sp2–sp3 systems, but alkyl boron or alkyl halides are prone to β-elimination and other side reactions, producing mixtures of products.

Read the full story by Suzanne Howson on Chemistry World.

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Tactile alternative to colour changes

Many instrument-free analytical methods, such as pH test strips and home pregnancy tests, indicate their results with a colour change. Now scientists in the US have devised a system that outputs a signal you can feel as well as see.

Source: Royal Society of Chemistry
Visual and tactile detection of ATP – gel shapes indicate a positive result.

Read the full story by Jennifer Newton on Chemistry World.

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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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