Chemical Science Blog

LAST CALL FOR ORAL ABSTRACTS – DEADLINE THIS FRIDAY 11TH MAY 2012

Directing Biosynthesis III (DBIII), 19 – 21 September 2012, University of Nottingham, UK

Please don’t miss this last opportunity to submit an oral abstract now to be part of a high profile conference featuring contributions from the most active groups in the UK, Europe, the USA and Japan working in this rapidly developing area.

This meeting builds on the two previous extremely successful conferences in a subject area which remains highly topical. As significant opportunities exist for engineering biosynthetic pathways in bacteria, fungi and plants for the directed biosynthesis of new natural products with new and beneficial properties. We expect the programme this year to generate a high profile event that you will not want to miss.

Confirmed Invited speakers:

Ikuro Abe, University of Tokyo, Japan
Mervyn Bibb, John Innes Centre, UK
David W. Christianson, University of Pennsylvania, USA
Christian Hertweck, Friedrich Schiller University Jena, Germany
Ben Liu, The University of Texas at Austin, USA
Professor Jim Naismith, University of St Andrews, UK
Joern Piel, University of Bonn, Germany
Professor Chris Schofield, University of Oxford, UK
David H Sherman, University of Michigan, USA
Dr David R Spring, University of Cambridge, UK
Tom Simpson, FRS, University of Bristol, UK
Yi Tang, UCLA, USA
NOW CONFIRMED – Craig Townsend, John Hopkins University, USA

A special symposium will take place within the Directing Biosynthesis III programme, recognising the achievements of three 2011 RSC award winners. Each of the winners will give a keynote lecture within the symposium.

A simple synthesis using ionic liquids reduces the cost of studying micro-porous oxide materials by NMR. This could help scientists uncover the chemistry and interactions that occur inside these materials.

The microporous structure of zeolites is used in a wide range of applications from catalysis through to gas separation however, studying interactions inside the pores is not trivial. Solid state NMR can probe the environment of 17O atoms lining the sides of the pores but unfortunately 17O has a very low natural abundance making isotopic enrichment the only practical way of conducting these experiments. The standard method of synthesising these compound uses expensive isotopically enriched water as the solvent but the majority of the enriched water ends up in bi-products or as waste solvent.

New approach allows scientists to understand what’s going on in zeolite pores

Read the full article in Chemistry World

Link to journal article
Ionothermal 17O Enrichment of Oxides using Microlitre Quantities of Labelled Water
John Griffin ,  Lucy Clark ,  Valerie Seymour ,  David Aldous ,  Daniel Dawson ,  Dinu Iuga ,  Russell Morris and Sharon Elizabeth Ashbrook
Chem. Sci., 2012, Accepted Manuscript, DOI: 10.1039/C2SC20155K

Scientists in the US have made a new MRI contrast agent for detecting copper(I) in cells. It could be used to detect changes in labile copper pools in live animals, which is associated with many disease states including Menke’s disease. It is the first in cellulo validation of the utility of a responsive Gd-based MR contrast agent to report on the metal status of the cell.

Link to journal article
A Cell-Permeable Gadolinium Contrast Agent for Magnetic Resonance Imaging of Copper in a Menkes Disease Model
E L Que, E J New and C J Chang
Chem. Sci., 2012, DOI: 10.1039/c2sc20273e

US scientists have applied high-throughput computational methods to explore thousands of possible (existing and hypothetical) MOF structures for separating krypton from xenon (selectively adsorbing Xe from a Xe/Kr mixture).

Xe and Kr are valuable gases, used in medical applications and lighting, but they are not straightforward to obtain as pure elements. These results should provide the MOF synthesis community with some new ideas for tailoring synthetic routes for specific gas adsorption/separation applications.

Link to journal article
Thermodynamic analysis of Xe/Kr selectivity in over 137,000 hypothetical metal-organic frameworks
B J Sikora et al
Chem. Sci., 2012, DOI: 10.1039/c2sc01097f

Vanadium complexes have been used extensively to catalyse olefin and alcohol oxidation. However, their application in C-H oxidation has not been well studied. US scientists say that commercially available Cp₂VCl₂ catalyses benzylic C-H oxidation selectively and effectively, giving no aromatic oxidation products.

Link to journal article
A Highly Selective Vanadium Catalyst for Benzylic C-H Oxidation
J-B Xia, K W Cormier and C Chen
Chem. Sci., 2012, DOI: 10.1039/c2sc20178j

US chemists have shown that trace impurities – below the sensitivity of standard characterisation techniques – can halve the efficiency of bulk heterojunction (BHJ) solar cells. Their finding means that initially promising materials for device applications may have been written off prematurely owing to their low efficiencies.

Trace impurities are difficult to detect owing to their similarity to donor molecules in solar cells. The impurities can significantly influence photovoltaic properties

Unlike traditional inorganic solar cells, polymer cells do not immediately create charge carriers but instead create electron-hole pairs called excitons over a donor-acceptor interface, which migrate to the electrodes. In BHJ solar cells, the donor-acceptor blend is mixed, creating this interface throughout the cell and transporting the charge carriers to the electrodes through an interpenetrating network. Although this network shows a significant improvement in efficiency over traditional cells, it is also highly sensitive to impurities, which can affect the carrier mobility and act as traps, increasing the chance of charge recombination before the exciton reaches an electrode.

A team led by Guillermo Bazan and Alan Heeger from the University of California, Santa Barbara, noticed that organic semiconductors’ effectiveness could vary from batch to batch. As the power conversion efficiencies of BHJ solar cells depend on the average molecular weight of the polymer, the team started by examining the definition of the structures and found that trace impurities in the donor of below 1% could halve device performance.

Read the full article in Chemistry World

Link to journal article
Role of trace impurities in the photovoltaic performance of solution processed small-molecule bulk heterojunction solar cells
Wei Lin Leong ,  Gregory C. Welch ,  Loren G. Kaake ,  Christopher J. Takacs ,  Yanming Sun ,  Guillermo C. Bazan and Alan J. Heeger
Chem. Sci., 2012, Advance Article, DOI: 10.1039/C2SC20157G

Scientists in Japan have developed the size-selective syntheses of the four “missing” cycloparaphenylenes (CPP)  ([9], [10], [11] and [13]), which complete the sequence of [6]-[16]CPP. It is important to have access to all of the CPPs in pure form for their future applications and for ring-size effect studies. The synthesis of CPPs was only recently realised (in 2008) and these molecules could find significant utility in supramolecular chemistry and materials science.

Link to journal article
Size-selective synthesis of [9]-[11] and [13]cycloparaphenylenes
Y Ishii et al
Chem. Sci., 2012, DOI: 10.1039/c2sc20343j