Chemical Science Blog

Scientists in Germany and Canada have developed a new way to capture sulfur dioxide gas. It could minimise the environmental impact of the gas, which causes acid rain.

The team made a series of frustrated Lewis pairs (FLPs) consisting of a bulky phosphane Lewis base component and a boron Lewis acid component. The FLPs rapidly and efficiently trap sulfur dioxide by adding the phosphane component to sulfur and the boron to oxygen.

Link to journal article
Reactions of Phosphorus/Boron Frustrated Lewis Pairs with SO₂
M Sajid et al
Chem. Sci., 2012, DOI: 10.1039/c2sc21161k

The surface chemistry of proteins makes them stable in complex biological environments. Scientists in the US have investigated why to enable peptide-based materials that resist non-specific interactions (stealth compounds) to be designed.

The cytoplasm is a crowded environment containing lots of different molecules but proteins resist non-specific interactions with these molecules. Understanding and mimicking nature’s resistance to non-specific interactions is key to addressing emerging challenges in chemistry, especially in practical applications where complex environments can degrade materials and surface coatings.

Here, the team has used structural bioinformatics to study proteins and molecular chaperones, which guide proteins from a misfolded or unfolded conformation back into a native conformation. They found that nature uses sequence design to modulate non-specific interactions so that the proteins function properly. Specifically, lysine and glutamic acid are the most abundant amino acids on the surface of proteins.

Link to journal article
Decoding nonspecific interactions from nature
A D White et al
Chem. Sci., DOI: 10.1039/c2sc21135a

Scientists in the UK have demonstrated that bottromycin (an antibiotic that works against MRSA) is biosynthesised from a larger precursor ribosomal peptide. This was proposed following a genome mining analysis of Streptomyces scabies and confirmed by a series of gene deletion experiments. The work also identifies S. scabies as a previously unknown producer of bottromycin. An almost identical gene cluster was also identified in S. bottropensis, an established bottromycin producer. Bottromycin is the first ribosomal peptide natural product that derives from the N-terminus of a larger prepeptide and the first terrestrial peptide to be directly ethylated at beta-positions.

Bottromycin is active in vitro but unstable in vivo so if scientists can engineer its biosynthesis to make unnatural analogues they might be able to make good new antibiotics. By identifying this pathway the team should facilitate the generation of a library of bottromycin-like antibiotics.

Link to journal article
Identification and characterisation of the gene cluster for the anti-MRSA antibiotic bottromycin: Expanding the biosynthetic diversity of ribosomal peptides
W J K Crone, F J Leeper and A W Truman
Chem. Sci., 2012, DOI: 10.1039/c2sc21190d

US scientists have come up with a general synthetic method to prepare macrocyclic tetracarbenes with first, second and third row transition metals from both sides of the periodic table, using a dimeric silver transmetallating reagent.

The facile synthesis of bidentate and tridentate N-heterocyclic carbenes (NHCs) coupled with their resistance to oxidation has made these chelating ligands an attractive alternative to phosphines for many applications. Despite numerous uses for these strong sigma-donor ligands, one class of chelating NHCs that has not been as thoroughly investigated is tetradentate carbenes.

Link to journal article
Exploiting a Dimeric Silver Transmetallating Reagent to Synthesize Macrocyclic Tetracarbene Complexes
Z Lu, S A Cramer and D M Jenkins
Chem. Sci., 2012, DOI: 10.1039/c2sc20628e

Highly active catalysts for manufacturing bulk and fine chemicals can be made by simply grinding metal acetate salts with pre-formed supports.

Heterogeneous catalysis is a key chemical manufacturing process and lies at the heart of green chemical processes. The use of catalysts can lead to greener reactions when compared to alternative routes. But many routes for making catalysts use halides as a starting point and the halides are difficult to remove from the final material.

UK scientists have prepared supported gold, palladium and gold-palladium catalysts by mixing the metal acetate precursors. The simple, reproducible and scalable preparation method ensures the catalysts prepared are halide free. They found that the removal of the halide from the preparation step and therefore from the final catalyst leads to a significant enhancement in performance compared to previously reported catalysts.

Link to journal article
Physical mixing of metal acetates: a simple, scalable method to produce active chloride-free bimetallic catalysts
S A Kondrat et al
Chem. Sci., 2012, DOI: 10.1039/c2sc20450a