Organic & Biomolecular Chemistry Blog

Scientists in Switzerland have synthesised a dye (3,4:3’,4’-bibenzo[b]thiophene-2,2’-disulfonate) that can be used as a sensitive and selective molecular probe for the fluorimetric detection of caffeine in water.

The system’s sensitivity and selectivity are higher than those of current synthetic caffeine sensors, so much so that caffeine can be detected in the sub-millimolar concentration range, the researchers claim. The team prepared sensor test strips on which a change in emission colour on addition of caffeine was easy to detect by the naked eye.

A ratiometric fluorescence sensor for caffeine
Nicolas Luisier, Albert Ruggi, Stephan N. Steinmann, Laurane Favre, Nicolas Gaeng, Clémence Corminboeuf and Kay Severin
DOI: 10.1039/C2OB26117K

US scientists have developed a cheap and simple way to examine the selectivity of the ketosynthase domain found in polyketide synthases.

Polyketide synthases are multicomponent enzyme systems that make polyketide natural products. They have received attention from researchers hoping to harness their potential as a platform for generating new and improved therapeutics. But the field of polyketide engineering has faced a constant struggle to overcome often strict substrate selectivities of the critical biosynthetic enzymes.

The new fluorescence-based method is much simpler and cheaper than previously used radiolabelling techniques and should enable improved understanding of how these biosynthetic machines function.

A Mechanism-Based Fluorescence Transfer Assay for Examining Ketosynthase Selectivity
Gitanjeli Prasad, Lawrence S. Borketey, Tsung-Yi Lin and Nathan A. Schanrr
Org. Biomol. Chem., 2012, Accepted Manuscript
DOI: 10.1039/C2OB26008E

Scientists in Switzerland have carried out the asymmetric synthesis of the 12-membered lactone alkaloids (+)-vertine and (+)-lythrine (structurally related and possessing a range of bioactivities), which has so far proved a challenge.

Peter Kundig and his group employed a range of strategies and novel tactics to overcome the synthetic challenge, and the strain in the two diastereomeric 12-membered lactone alkaloids was ultimately overcome via Z-selective alkene metathesis.

Asymmetric synthesis of (+)-vertine and (+)-lythrine
Peter Kundig, Laetitia Chausset-Boissarie, Roman Arvai, Graham Cumming and Laure Guénée
DOI: 10.1039/C2OB25880C

The 2011 Journal Citation Reports ® (Thomson Reuters, 2012) have just been released, which showed:

Organic & Biomolecular Chemistry: 3.696

MedChemComm: 2.8         (Partial IF only, based on five issues)

Natural Product Reports: 9.79

The Cambridge Editorial Office would like to thank everyone involved for their hard work and dedication to all three journals over the years. In particular, we would like to thank all of our Associate Editors, Editorial and Advisory Board members, authors and referees, without whom none of this would have been possible.

With another successful year in the bag, we hope you will join us in making this year even better…

Read more about the 2011 Impact Factors from across RSC Publishing on the RSC Publishing Blog.

Scientists in the Netherlands and Germany have synthesised a series of new pyrazine substituted ligands that are promising for actinide separation.

The team used the ligands to differentiate trivalent actinides from lanthanides, with a very good selectivity for Am³⁺ over Eu³⁺ with separation factors up to 40 at pH 1 at 0.01 mol/L ligand concentration.

The ligands are resistant to strong acids and water soluble, which makes them ideal for the innovative SANEX concept (Selective ActiNide Extraction).

The team says: ‘It is basically a DIAMEX (DIAMide EXtraction) process (An(III) and Ln(III) coextraction) with selective back extraction of An(III) from the loaded organic phase. Instead of a water-soluble complexing agent such as diethylene triamine pentaacetic acid, which requires in most cases buffering agents to adjust the pH, the search is for stronger acid resistant water-soluble ligands.’

Palladium–catalyzed cross-coupling of various phosphorus pronucleophiles with chloropyrazines: synthesis of novel Am(III)-selective extractants
W. Verboom, Nicolai I. Nilishkin, Jurriaan Huskens, Giuseppe Modolo, Jana Assenmacher and Andreas Wilde
DOI: 10.1039/C2OB25787D

Nanopore-forming materials have many potential applications in chemistry and biology, including DNA sequencing. However, only very limited designs of synthetic nanopores exist in the literature. US scientists have made circular molecules made of sugars that can stack on top of one another to form a transmembrane pore and act as carriers to shuttle the guest molecules across the membrane.

Hydrogen bond-assisted macrocyclic oligocholate transporters in lipid membranes
Lakmini Widanapathirana, Xueshu Li and Yan Zhao
DOI: 10.1039/C2OB25301A

A judicious choice of precipitation conditions can lead to self-sorting of equilibrating mixtures of aromatic aldehydes and substituted anilines into a handful of imine products, say researchers from the US.

You might expect to get quite a few different products but because the least soluble imine precipitates, the mixture re-equilibrates to generate more of that compound. Eventually, all precursors to the least soluble imine are exhausted and the mixture is reduced in complexity. Only the most and the least soluble imines are produced without any of the “in between” species.

A mixture of as many as nine imines could be self-sorted into just three compounds, they say.

Precipitation-driven self-sorting of imines
Rio Carlo Lirag , Karolina Osowska and Ognjen Š. Miljanić
DOI: 10.1039/C2OB25736J