Chemical Science Blog

The well-known semiconductor CdS can be transformed into an efficient, visible light photocatalyst that can selectively oxidise C-H bonds using molecular oxygen as the oxidant under ambient conditions, say scientists from China.

The team attributes the high performance to the catalyst’s cubic phase, high surface area and efficient separation of photogenerated charge carriers upon visible light irradiation. It is easy to make and could be used to activate C-H selectively to make fine chemicals, they say.

Link to journal article
Transform CdS to an efficient visible light photocatalyst for selective oxidation of saturated primary C–H bonds under ambient conditions
Y Zhang et al
Chem. Sci., 2012, DOI: 10.1039/c2sc20603j

Scientists in the US and Saudi Arabia have made a new family of conjugated polymers that change colour in response to changes in their redox state. The stimuli-responsive polymers are the first example where an azulene building block is incorporated into the polymer backbone through linkages in the 7-membered ring, rather than the more synthetically accessible 5-membered ring.

The polymers’ properties may be of great importance for developing new organic field-effect transistors, organic light-emitting diodes, and dye-sensitised organic solar cells.

Link to journal article
Azulene-Based Conjugated Polymers: Unique Seven-Membered Ring Connectivity Leading to Stimuli-Responsiveness
Masahito Murai , Elizabeth Amir , Roey J. Amir and Craig J. Hawker
Chem. Sci., 2012, DOI: 10.1039/c2sc20615c

While most people over a certain age are trying to slow down the ageing process, scientists from the UK and Canada are trying to speed it up to help them make new materials more cleanly.

‘Accelerated ageing’ could become a new paradigm for the clean, low energy and solvent-free synthesis of metal-organic materials, claim the researchers. They were inspired by the slow geological processes of mineral weathering, which convert metal oxides and sulfides to metal-organic materials by exposing them to small organic molecules. By accelerating this process, they claim materials can be made without the continuous input of mechanical energy, high temperatures or organic solvents. Their simple process involves exposing a mixture of a metal oxide and an organic ligand to catalytic amounts of an ammonium salt at mild temperature and high humidity.

Link to journal article
Accelerated aging: a low energy, solvent-free alternative to solvothermal and mechanochemical synthesis of metal-organic materials
Tomislav Friscic, Matthew J Cliffe, Cristina Mottillo, Robin S Stein and Dejan-Kresimir Bucar
Chem. Sci., 2012, DOI: 10.1039/c2sc20344h

UK scientists have isolated and identified the biosynthesis genes of the metabolite coelimycin P1 (a yellow pigment, unprecedented in nature to the team’s knowledge) by Streptomyces coelicolor M145, using a combination of genetic experiments, bioinformatic analyses and structural analyses.

Analysing the genome sequences of plants, bacteria and filamentous fungi, together with the screening of extracts of novel organisms isolated from underexplored habitats, revealed that many (perhaps most) structurally novel bioactive natural products remain to be discovered. Sequencing the complete or partial genomes of several Streptomyces species and related actinomycetes has shown that they invariably contain numerous cryptic gene clusters with the potential to direct the production of hitherto undiscovered bioactive natural products, say the researchers.

Link to journal article
Structure and biosynthesis of the unusual polyketide alkaloid coelimycin P1, a metabolic product of the cpk gene cluster of Streptomyces coelicolor M145
Juan-Pablo Gomez-Escribano, Lijang Song, David Fox, Valerie Yeo, Mervyn Bibb and Gregory L Challis
Chem. Sci., 2012, DOI: 10.1039/c2sc20410j

Certain transition metal ions, particularly Fe, Co and Ni, can significantly improve the catalytic activity of molybdenum sulfide hydrogen evolution catalysts, claim scientists in Switzerland.

Sunlight-driven water splitting is an attractive method for solar energy conversion and storage. Achieving efficient water splitting requires active hydrogen evolution catalysts. Recently, molybdenum sulfide materials have emerged as a class of promising hydrogen evolution catalysts because of their high abundance, low cost and high activity. Xile Hu, at the Federal Polytechnic School of Lausanne, and colleagues, incorporated metal ions into amorphous molybdenum sulfide and demonstrated up to a 12-fold increase in exchange current density and a 10-fold increase in the current density at a given overpotential at pH = 7.

Link to journal article
Fe, Co, and Ni Ions Promote the Catalytic Activity of Amorphous Molybdenum Sulfide Films for Hydrogen Evolution
Daniel Merki, heron vrubel, lorenzo rovelli, Stephan Fierro and Xile Hu
Chem. Sci., 2012, DOI: 10.1039/c2sc20539d

Scientists in the US have reported a series of novel tris-diphosphane complexes that use a unique diphosphane constructed from elemental phosphorus. The synthesis combines a simple synthesis of the binucleating ligand together with the efficient self assembly of a novel class of elaborate dinuclear metal complexes. The cages that form are stable during ligand substitution at the axial positions so they could be used as components of coordination polymers and supramolecular structures.

Link to journal article
Bicyclic Dinuclear tris-(Ditopic Diphosphane) Complexes of Zerovalent Group 10 Metals
Daniel Tofan and C Cummins
Chem. Sci., 2012, Accepted Manuscript, DOI: 10.1039/C2SC20559A