Author Archive

What’s left isn’t always right in total synthesis

Using detective skills that would make Hercule Poirot proud, researchers in the US have solved a longstanding mystery around the absolute configuration of natural product (+)-frondosin B.1

Source: Royal Society of Chemistry Summary of the enantioselective frondosin B syntheses reported to date

(+)-Frondosin B is part of a family of marine sesquiterpenes found in underwater sponges that exhibit anti-inflammatory properties and have potential applications in anticancer and HIV therapy. Starting with Samuel Danishefsky’s route in 2001,2 there have been 5 total syntheses of (+)-frondosin B. However, due to a discrepancy in the optical rotation of the final product during Dirk Trauner’s 2002 synthesis,3 which was observed to have S rather than the expected R configuration, there has been a fierce debate in the synthetic community about the true stereochemistry at C8 in the natural product. After more than decade of attempts by synthetic organic chemists to explain this, particularly focused on different inversion processes, no definitive answer had arisen.

Read the full story by Jason Woolford on Chemistry World.

1 L A Joyce et al, Chem. Sci., 2017, DOI: 10.1039/c7sc04249c (This paper is open access.)

2 M Inoue et al, J. Am. Chem. Soc., 2001, 123, 1878 (DOI: 10.1021/ja0021060)

 

 

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Benchmark for molecular machine learning

A team at Stanford University in the US has developed a benchmark for machine learning in chemistry. By providing a consistent way to test different techniques across a range of chemical data, it aims to accelerate the growth of this new type of scientific problem-solving.

Source: Royal Society of Chemistry
MoleculeNet curates multiple public datasets, establishes metrics for evaluation, and offers high quality open-source implementations of multiple previously proposed molecular featurisation and learning algorithms (released as part of the DeepChem open source library)

Machine learning methods train a computer to efficiently get from raw data to already-known answers. Once the expected results are consistently reproduced, the software is ready to perform the same task with entirely new data. To fairly compare different learning approaches, research groups around the globe need to train and test their methods using a shared set of problems. Reference databases already exist for images and text; MoleculeNet, an extension of the DeepChem project, provides such a benchmark for chemistry.

Read the full story by Alexander Whiteside on Chemistry World.

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Protonation enhances water splitting

Researchers in China and Singapore have designed a new platinum electrocatalyst for the hydrogen evolution reaction that outperforms existing catalysts and also performs better than theoretical calculations suggest it should.

Source: Royal Society of Chemistry
Transmission electron microscopy image of the new electrocatalyst showing its branched structure

Hydrogen can serve as a clean fuel, and electrochemical water splitting through the hydrogen evolution reaction is one way to generate this valuable resource. Many current electrocatalysts for the hydrogen evolution reaction are based on platinum, which, although expensive, can be very efficient. Researchers are always looking to improve the efficiency of platinum electrocatalysts to make the hydrogen evolution reaction a suitable replacement for fossil fuels.

Read the full story by Suzanne Howson on Chemistry World.

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Peptide vehicle drives CRISPR delivery of Cas9 into cells

Scientists in Spain have put forward what they describe as the first non-covalent strategy for delivering the CRISPR Cas9 ribonucleoprotein into cells.1

Cas9 is a large RNA-guided DNA endonuclease enzyme that is responsible for accurately recognising and cutting the desired sequence of DNA in a cell’s genome during the gene editing process known as CRISPR. At the moment, CRISPR scientists typically transfect cells with a plasmid containing instructions to make Cas9: however, this isn’t ideal as it might result in permanent DNA recombination and persistent expression, which could have adverse effects. Researchers are therefore exploring methods that deliver Cas9 into cells.

Read the full story by Adrian Robinson on Chemistry World.

Peptide/Cas9 nanostructures for ribonucleoprotein cell membrane transport and gene edition

1 I Lostalé-Seijo et al, Chem. Sci., 2017, DOI: 10.1039/c7sc03918b (This paper is open access.)

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Zirconium MOF buckles under dynamite pressure

Scientists in the US have found that a metal–organic framework (MOF) known for its robustness takes in the same amount of energy as a TNT blast releases when it breaks.

Shock-absorber MOF

Source: Royal Society of Chemistry After compression, the effective number of Zr–carboxylate oxygen bonds (shown in yellow) for each Zr(IV) ion decreased from 4 to ≈2

MOF materials are porous framework solids whose typical applications include gas storage, separation and catalysis. Scientists have studied the zirconium-based MOF, UiO-66, in more detail than most. It’s easily synthesised, has a well-known structure and is strong. Unlike some other MOFs, it doesn’t react with water, and on removing its residual solvent, the framework remains intact with true, empty voids.

Read the full story by Emma Stephen on Chemistry World.

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