Chemical Science Blog

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

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

Scientists in the US have developed an acylation reagent that can address shortcomings in the acylation of several complex natural products and therapeutics that are widely used in disease treatment and clinical trials. 

The reactions include the inefficient regioselective acylation in rapamycin and paclitaxel and the inefficient acylation of tertiary hydroxyl groups in camptothecin.

Link to journal article
Zinc Complex Mediated Regioselective O-Acylation of Therapeutic Agents
R Tong and J Cheng
Chem. Sci., 2012, DOI: 10.1039/c2sc20239e

Scientists in Canada have used 2D electronic spectroscopy to understand the excitons and charge transfer dynamics (created upon photo excitation) in two conjugated polymers used in organic photovoltaic devices.

The study focuses on the effect of backbone conformation on these properties and the team has found that the weakening of electron-hole correlation controlled by an increasing number of units on the donor and acceptor moieties can lead to higher efficiency of photovoltaic devices by facilitating the charge-transfer process at the heterojunction interfaces.

Although other physical processes should also be taken into account, this study may explain why the photovoltaic devices based not only on the blend of PCDTBT (a popular copolymer for preparing efficient solar cells) and PCBM (an electron acceptor), but also on PCDTBT alone, are efficient.

Link to journal article
Ultrafast relaxation of charge-transfer excitons in low-bandgap conjugated copolymers
I Hwang et al
Chem. Sci., 2012, DOI: 10.1039/c2sc20078c

Scientists in China and Australia have directed the self-assembly of colloidal nanoparticles (NPs) of Au and CdTe into perfect hexagonal microflakes and ultralong microwires, respectively, via stepwise reduction of the electrostatic repulsion potential of neighbouring NPs in the dispersions with the help of L-cysteine.

The work should provide a fundamental basis for better interpretation and prediction of shape-controlled crystallisation and organisation of nanoscale building blocks to mesoscopic and macroscopic artificial solids.

Link to journal article
Shape-Controlled Self-Assembly of Colloidal Nanoparticles
B Zhang, W Zhao and D Wang
Chem. Sci., 2012, DOI: 10.1039/c2sc00016d