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A cheaper way to catalyse the oxidative annulation of alkynes

13 Oct 2011

The first ruthenium-catalysed oxidative annulation of alkynes with air as an oxidant has been done by scientists in Germany.

The team used an inexpensive ruthenium catalyst for aerobic C-H bond functionalisations, providing novel access to structural motifs of bioactive alkaloids.

Oxidative annulations reactions of alkynes by C-H bond cleavages provides a route to polycyclic heteroarenes. Ruthenium-catalysed methods use stoichiometric amount of copper(II) or silver(II) salts, but these lead to heavy metal by-products. Rhodium-catalysed methods are known but this ruthenium method is cheaper with improved scope and chemoselectivity.

Reference:
Ruthenium-catalyzed aerobic oxidative coupling of alkynes with 2-aryl-substituted pyrroles
L Ackermann, L Wang and A V Lygin, Chem. Sci., 2011,
DOI: 10.1039/c1sc00619c

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Promising therapeutics for heart failure

06 Oct 2011

Complexes for future nitroxyl (HNO) therapies have been made by scientists in the US, South Africa and Norway. HNO donors have been used as anti-alcoholism agents and are proving to be promising therapeutics for heart failure.

The team made ferric nitric oxide complexes and described the first insight into the electronic structure, reactivity and potential fate of these {FeNO}⁸ complexes in biology. The researchers say that {FeNO}⁸ could be used as a nitroxyl donor at ambient temperature and physiological pH.

Reference:
A thermally stable {FeNO}⁸ complex: properties and biological reactivity of reduced MNO systems
A K Patra, K S Dube, B C Sanders, G C Papaefthymiou, J Conradie, A Ghosh and T C Harrop, Chem. Sci., 2011
DOI: 10.1039/c1sc00582k

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Cleaner gases for industrial energy applications

06 Oct 2011

Japanese scientists have improved the gas separation efficiencies of porous materials by precisely tuning the framework’s flexibility. Separating gas mixtures is important for generating cleaner gases for industrial energy applications. For example, carbon dioxide needs to be removed from biogas and ethane from natural gas to increase the methane content.

Porous coordination polymers are promising candidates for gas separation and this new study show that specific design of them can contribute to improved industrial separation processes.

Reference:
A solid solution approach to 2D coordination polymers for CH4/CO2 and CH4/C2H6 gas separation: equilibrium and kinetic studies
S Horike, Y Inubushi, T Hori, T Fukushima and S Kitagawa, Chem. Sci., 2011
DOI: 10.1039/c1sc00591j

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DNA toxic gas detector

29 Jul 2011

Scientists in the US have developed a sensitive and simple sensor that could be used to detect toxic gases occurring in urban areas.

Gases such as chlorine, sulfur dioxide and ammonia are toxic and are often emitted by industrial processes and agriculture. The gas molecule structures are small and simple, which makes them difficult to differentiate using sensors. Methods to detect such pollutants in urban environments thus require expensive equipment that has to be used in a laboratory.

Eric Kool and colleagues at Stanford University designed a sensor based on the structure of DNA, where base pairs were replaced with one of four fluorescing aromatic monomers. The DNA scaffold gave the sensor a stable structure where the monomers were stacked over each other. Using four sensing molecules in the structures produced a pattern of fluorescence outputs that could be used to differentiate between a mixture of toxic gases.

A combination of three structures could detect and differentiate between eight toxic gases

Read the full Chemistry World news story here

Link to journal Article
DNA polyfluorophores as highly diverse chemosensors of toxic gases
Chi-Kin Koo, Florent Samain, Nan Dai and Eric T. Kool
Chem. Sci., 2011, DOI: 10.1039/c1sc00301a

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Measuring cells’ oxygen levels with PEBBLEs

09 Mar 2011

Scientists in Germany have developed a strategy to visualise oxygen concentrations in cells to better understand its role in biological reactions such as metabolism.

Hans Gorris from the University of Regensburg and colleagues have embedded two luminescent dyes within polystyrene particles, which were taken up by cells. One is a red light-emitting indicator dye that alters its luminescence depending on the oxygen concentration; the second is a green light-emitting dye that acts as a reference and is not sensitive to oxygen. The colours enabled the dyes to be monitored on the green and red channels in a red-green-blue (RGB) digital camera, together with a fluorescence microscope.

Schematic drawing of a ratiometric oxygen-sensitive polystyrene PEBBLE

See Chemistry World for the full news story

Link to journal article
Self-referenced RGB colour imaging of intracellular oxygen
Xu-dong Wang, Hans H. Gorris, Judith A. Stolwijk, Robert J. Meier, Dominik B. M. Groegel, Joachim Wegener and Otto S. Wolfbeis
Chem. Sci., 2011, DOI: 10.1039/c0sc00610f

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A cheaper way to catalyse the oxidative annulation of alkynes

Promising therapeutics for heart failure

Cleaner gases for industrial energy applications

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DNA toxic gas detector

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Measuring cells’ oxygen levels with PEBBLEs

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