Thursday, November 10, 2011

Astrobiologists discover 'sweet spots' for the formation of complex organic molecules in the galaxy

 Scientists within the New York Center for Astrobiology at Rensselaer Polytechnic Institute have compiled years of research to help locate areas in outer space that have extreme potential for complex organic molecule formation. The scientists searched for methanol, a key ingredient in the synthesis of organic molecules that could lead to life. Their results have implications for determining the origins of molecules that spark life in the cosmos.

The findings will be published in the Nov. 20 edition of The Astrophysical Journal in a paper titled "Observational constraints on methanol production in interstellar and preplanetary ices." The work is collaboration between researchers at Rensselaer, NASA Ames Research Center, the SETI Institute, and Ohio State University.

"Methanol formation is the major chemical pathway to complex organic molecules in interstellar space," said the lead researcher of the study and director of the NASA-funded center, Douglas Whittet of Rensselaer. If scientists can identify regions where conditions are right for rich methanol production, they will be better able to understand where and how the complex organic molecules needed to create life are formed. In other words, follow the methanol and you may be able to follow the chemistry that leads to life.

Using powerful telescopes on Earth, scientists have observed large concentrations of simple molecules such as carbon monoxide in the clouds that give birth to new stars. In order to make more complex organic molecules, hydrogen needs to enter the chemical process. The best way for this chemistry to occur is on the surfaces of tiny dust grains in space, according to Whittet. In the right conditions, carbon monoxide on the surface of interstellar dust can react at low temperatures with hydrogen to create methanol (CH3OH). Methanol then serves as an important steppingstone to formation of the much more complex organic molecules that are required to create life. Scientists have known that methanol is out there, but to date there has been limited detail on where it is most readily produced.

What Whittet and his collaborators have discovered is that methanol is most abundant around a very small number of newly formed stars. Not all young stars reach such potential for organic chemistry. In fact, the range in methanol concentration varies from negligible amounts in some regions of the interstellar medium to approximately 30 percent of the ices around a handful of newly formed stars. They also discovered methanol for the first time in low concentrations (1 to 2 percent) in the cold clouds that will eventually give birth to new stars.

The scientists conclude in the paper that there is a "sweet spot" in the physical conditions surrounding some stars that accounts for the large discrepancy in methanol formation in the galaxy. The complexity of the chemistry depends on how fast certain molecules reach the dust grains surrounding new stars, according the Whittet. The rate of molecule accumulation on the particles can result in an organic boom or a literal dead end.

"If the carbon monoxide molecules build up too quickly on the surfaces of the dust grains, they don't get the opportunity to react and form more complex molecules. Instead, the molecules get buried in the ices and add up to a lot of dead weight," Whittet said. "If the buildup is too slow, the opportunities for reaction are also much lower."

This means that under the right conditions, the dust surrounding certain stars could hold greater potential for life than most of its siblings. The presence of high concentrations of methanol could essentially jumpstart the process to create life on the planets formed around certain stars.

The scientists also compared their results with methanol concentrations in comets to determine a baseline of methanol production in our own solar system.

"Comets are time capsules," Whittet said. "Comets can preserve the early history of our solar system because they contain material that hasn't changed since the solar system was formed." As such, the scientists could look at the concentrations of methanol in comets to determine the amount of methanol that was in our solar system at its birth.

What they found was that methanol concentrations at the birth of our solar system were actually closer to the average of what they saw elsewhere in interstellar space. Methanol concentrations in our solar system were fairly low, at only a few percent, compared to some of the other methanol-dense areas in the galaxy observed by Whittet and his colleagues.

"This means that our solar system wasn't particularly lucky and didn't have the large amounts of methanol that we see around some other stars in the galaxy," Whittet said.

"But, it was obviously enough for us to be here."

The results suggest that there could be solar systems out there that were even luckier in the biological game than we were, according to Whittet. As we look deeper into the cosmos, we may eventually be able to determine what a solar system bursting with methanol can do.

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The above story is reprinted from materials provided by Rensselaer Polytechnic Institute.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

D. C. B. Whittet, A. M. Cook, Eric Herbst, J. E. Chiar, S. S. Shenoy. Observational constraints on methanol production in interstellar and preplanetary ices. The Astrophysical Journal, 2011; 742 (1): 28 DOI: 10.1088/0004-637X/742/1/28

Unprecedented formation of a boron-boron covalent bond opens a new corner of chemistry

The compound that the researchers made features two held together by a shared pair of . For other elements—carbon, for example—that would be a typical bond, but electron-poor boron tends to prefer a more complex arrangement. In the boron compound diborane (B2H6), for example, two boron atoms are bridged by hydrogen atoms, with each boron–hydrogen–boron bond sharing a single pair of electrons across three atoms rather than the usual two.

Theory has long predicted that by pumping extra electrons into a compound such as diborane, the boron–hydrogen–boron structure should break down to form a boron–boron single bond. Until now, however, all such attempts to make and isolate such a structure had failed, instead generating clusters or single boron species.

Matsuo and Tamao’s strategy for generating the boron–boron bond was to start with a borane precursor where each boron atom was fitted with a bulky side-group known as an Eind group. The researchers suspected that previous attempts probably succeeded in generating the boron–boron single bond but failed to protect that structure from quickly falling apart through over-reaction. Using the bulky side-groups, they were able to block these over-reaction processes, and successfully isolate the desired boron–boron single bond (Fig. 1).

Having discovered a new way to make the boron–boron bond, the next step will be to assess its chemistry and reactivity, and to explore related structures, says Shoji. The bond has already proved to be relatively stable: the team has shown that if protected from air and moisture, the boron–boron compound can be stored for months at ambient temperature. It can also be converted into a three-membered ring, in which a bridging hydrogen atom is the third member, forming a molecule with potentially useful properties. “We think that the hydrogen-bridged boron–boron bond has a double-bond character,” says Matsuo. “We would like to explore the new reaction chemistry of multiply bonded boron species.”

More information: Shoji, Y., et al. Boron–boron ?-bond formation by two-electron reduction of a H-bridged dimer of monoborane. Journal of the American Chemical Society 133, 11058–11061 (2011).

Provided by RIKEN (news : web)

When the fat comes out of food, what goes in?

In the article Melody Bombgardner, C&EN Senior Business Editor, explains that processors usually face the problem of reproducing the texture or "mouth feel" of products that have cut back on fat, sugar and gluten. More and more of these products are appearing on supermarket shelves in response to changing preferences of health-conscious consumers. Food companies are in a quandary in selecting replacements, because of a parallel consumer backlash against products with long complicated lists of ingredients with the names of tongue-twisting chemical compounds.

The article describes how a host of ingredients derived from Mother Nature, are assuming increasingly important roles in giving those processed foods a satisfying taste. It includes a "mouth map" used to help formulate "light" foods so that they taste like the full-fat versions. The article also features one sidebar on natural food ingredients used to give processed foods a satisfying texture and another on food ingredients that do double-duty as ingredients in toothpastes, shampoo, skin creams, and even oil and gas drilling.

More information: Call In The Food Fixers -

Provided by American Chemical Society (news : web)

Research paper on cancer drug accorded 'VIP' status

The drug, originally known as STX64 and now as Irosustat, was designed and chemically synthesised in the Group of the University’s Department of Pharmacy & Pharmacology.

STX64 and its associated intellectual property formed part of the assets of the Bath-Imperial College spin-out company Sterix Ltd that was co-founded by Professor Barry Potter and was acquired by the pharmaceutical company Ipsen in 2004.

The drug has been developed by Ipsen in recent years, with human clinical trials carried out in hormone-dependent breast cancer, endometrial cancer and in male prostate cancer.

The drug can be given orally and is termed a ‘first-in-class’ irreversible steroid sulfatase inhibitor. It works by blocking an enzyme pathway that gives rise to precursors of the steroid hormones oestrogen and an androgen that can trigger the growth of hormone-dependent tumours.

The new paper, entitled ’Structure-activity relationship of the clinical steroid sulfatase inhibitor Irosustat (STX64, BN83495),’ has appeared in the November issue of the journal and describes how the research team has modified the chemical structure of the drug to explore the effects on biological activity.

Referee reports on the paper were so strong that the journal ChemMedChem accorded it coveted ‘VIP’ status and also invited the authors to design a cover feature for the publication.

Professor Potter, with colleagues Dr Lawrence Woo and Dr Mark Thomas of the Department of Pharmacy & Pharmacology, designed an imaginative cover feature illustrating the drug molecule flanked by renderings of the target enzyme, all superimposed upon a false colour staining of the target protein in malignant breast cancer cells.

The publisher Wiley has also issued a feature on this paper in its own Chem Views online news magazine entitled ’Best in Class’.

Professor Potter said: “It is highly rewarding for the whole team to see the progression of this drug from the bench in a University of Bath synthetic laboratory all the way into diverse major clinical trials in cancer patients and also to see such continuing academic peer-recognition.

“This work emphasises the strength of medicinal chemistry at the University of Bath and demonstrates that academic scientists can play a key role in the discovery and development processes, traditionally a preserve of the pharmaceutical industry.”

More information: The full paper can be accessed through the ChemMedChem website.

Provided by University of Bath (news : web)

Electrochemistry controlled with a plasma electrode

ScienceDaily (Oct. 20, 2011) — Engineers at Case Western Reserve University have made an electrochemical cell that uses a plasma for an electrode, instead of solid pieces of metal. The technology may open new pathways for battery and fuel cell design and manufacturing, making hydrogen fuel and synthesizing nanomaterials and polymers.

A description of the research is now published in the online edition of the Journal of the American Chemical Society.

"Plasmas formed at ambient conditions are normally sparks which are uncontrolled, unstable and destructive," said Mohan Sankaran, a chemical engineering professor and senior author of the paper. "We've developed a plasma source that is stable at atmospheric pressure and room temperature which allows us to study and control the transfer of electrons across the interface of a plasma and an electrolyte solution."

Sankaran worked with former students Carolyn Richmonds and Brandon Bartling, current students Megan Witzke and Seung Whan Lee and fellow chemical engineering professors Jesse Wainright and Chung-Chiun Liu.

The group used a traditional set up with their nontraditional electrode.

They filled an electrochemical cell, essentially two glass jars joined with a glass tube, with an electrolyte solution of potassium ferricyanide and potassium chloride.

For the cathode, argon gas was pumped through a stainless steel tube that was placed a short distance above the solution. A microplasma formed between the tube and the surface.

The anode was a piece of silver/silver chloride.

When a current was passed through the plasma, electrons reduced ferricyanide to ferrocyanide.

Monitoring with ultraviolet-visible spectrophotometry showed the solution was reduced at a relatively constant rate and that each ferrycyanide molecule was reduced to one ferrocyanide molecule.

As the current was raised, the rate of reduction increased. And testing at both electrodes showed no current was lost.

The researchers, however, found two drawbacks.

Only about one in 20 electrons transferred from the plasma was involved in the reduction reaction. They speculate the lost electrons were converting hydrogen in the water to hydrogen molecules, or that other reactions they were unable to monitor were taking place. They are setting up new tests to find out.

Additionally, the power needed to form the plasma and induce the electrochemical reactions was substantially higher than that required to induce the reaction with metal cathodes.

The researchers know their first model may not be as efficient as what most industries need, but the technology has potential to be used in a number of ways.

Working with Sankaran, Seung has scanned a plasma over a thin film to reduce metal cations to crystalline metal nanoparticles in a pattern.

"The goal is to produce nanostructures at the same small scale as can be done now with lithography in a vacuum, but in an open room," Seung said.

They are investigating whether the plasma electrode can replace traditional electrodes where they've come up short, from converting hydrogen in water to hydrogen gas on a large scale to reducing carbon dioxide to useful fuels and commodity chemicals such as ethanol.

The researchers are fine-tuning the process and testing for optimal combinations of electrode design and chemical reactions for different uses.

"This is a basic idea," Sankaran said. "We don't know where it will go."

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The above story is reprinted from materials provided by Case Western Reserve University.

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Journal Reference:

Carolyn Richmonds, Megan Witzke, Brandon Bartling, Seung Whan Lee, Jesse Wainright, Chung-Chiun Liu, R. Mohan Sankaran. Electron-Transfer Reactions at the Plasma–Liquid Interface. Journal of the American Chemical Society, 2011; : 111017135037002 DOI: 10.1021/ja207547b

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