A candidate of choice is formic acid: it is a small molecule, solid at ambient conditions, that can easily be converted to hydrogen (and carbon dioxide as a side-product). Alternatively, hydrogen (from renewable sources) and carbon dioxide can be combined to generate formic acid. However, the formation or decomposition of formic acid are not spontaneous, and catalysts are required in order for these reactions to proceed at useful rates.

In this context, a new catalyst was developed by Albert Boddien et al. from the Leibniz-Institut für Katalyse in Rostock, Germany, that can efficiently liberate hydrogen from formic acid. Importantly, the catalytic system, reported recently in Science, involved the use of an iron salt and a phosphine dissolved in propylene carbonate. The process is remarkable since it avoids the use of expensive, rare metals or highly toxic solvents – in addition to evolving hydrogen with high efficacy. Mechanistic investigations were performed based on nuclear magnetic resonance spectroscopy, kinetic studies, and density functional theory calculations to explain possible reaction mechanisms.

The catalytic cycle involving formic acid (HCOOH). The catalyst presented in the mentioned article is indicated here as 'catalyst B'.

This work represents an important step towards the use of formic acid as a safe, user-friendly surrogate for hydrogen in the frame of renewable energies.

The importance of rare earth elements is less obvious that that of more common resources – we don’t eat them nor power our cars with them. However, their use in many of recent high-tech innovations make them an invaluable resource for the decades to come: computer hard drives contain neodymium and dysprosium, tellurium is used in solar cells, and several rare earth elements are so far irreplacable in optical devices such as lasers, LEDs and phosphors. Although rare earths are not so scarce, their distribution on earth is uneven – and more than 90% are currently produced in China. The US and other countries consider (re)opening mining sites, but for the upcoming years, China will have an increasing weight and decision power over prices and distribution of rare earths.

In order to ensure a sustainable use of scarce elements, strong incentives will be needed. For example in Japan, a country without such resources which industry highly depends on importation, the Element Strategy Initiative is a good example of such efforts.[2] Besides reuse and recycling, the potential lack of such elements can be regarded as another challenge for researchers worldwide, who are trying to find alternative materials, thus reducing the need for rare earths in the future.[3]

More generally, the rare earth issue reflects a more general problem that may occur in the upcoming decades: I remember a seminar where a professor mentioned that, if the current trends go on, we will be running out of most precious metals (e.g., rhodium, platinum) in less than a hundred years. Further, resources of lithium (for rechargeable batteries) and phosphorous (for fertilizers) are also limited. In every single field, from ’simple’ food production to state-of-the-art technologies, the limited resources of our planet will eventually constrain us to play the equilibrist’s game of long-term sustainability.

References:

[1] Nature Materials 2011, 10, 157. DOI: 10.1038/nmat2985
[2] Nature Materials 2011, 10, 158. DOI: 10.1038/nmat2969
[3] Nature Materials 2011, 10, 162. DOI: 10.1038/nmat2973

See also:

Nature Photonics 2011, 5, 1. DOI: 10.1038/nphoton.2010.308

The compound has been known for decades to mimic the effects of estrogen in the body. Hence, particular concerns have been raised regarding the absorption of BPA by pregnant women and babies. Particularly, it was suggested that BPA-containing baby bottles should be avoided, since they are extremely likely to leach BPA in baby drinks. Further, BPA was related to illnesses such as obesity, heart disease, cancer, diabetes, fertility problems, and birth defects.

So far, Canada and Australia have been the first countries to classify BPA as toxic (despite recriminations from the chemical industry), and France and Denmark had already banned BPA from baby bottles. On 25 November, 2010, the European Union executive commission decided to ban production, and commercialization, of polycarbonate-based baby bottles containing bisphenol A. The new regulations will be enforced during the first semester of 2011.

However, some criticize the decision, calling it more political than based on sound science, and not every country is ready to ban BPA. In Swizerland, where we usually like to do things differently, the Federal Office of Public Health considers BPA as non-harmful for consumers, since only high doses are known to be problematic. According to them, a ban on BPA would lead manufacturers to employ other, lesser known compounds, which toxicity is still unknown.

Then, is a ban on BPA an over-reaction or a wise precaution? Only the future (and more experiments) will tell.

Further reading:

http://www.nature.com/news/2010/101104/full/news.2010.581.html

This concept was translated at the molecular level, as researchers from Osaka University, Japan, recently reported in Nature Chemistry.  The team led by Prof. Akira Harada developed different polymers bearing either cyclodextrin  rings (a so-called molecular host) or residues that like to sit inside the cyclodextrins (ie., molecular guests). When pieces of both polymers are suspended in water, they find each other and stick together thanks to host-guest interactions at the cyclodextrin sites.

Further, they demonstrated that by modifying the host and/or guest moieties, the strength of the sticking interaction can be tuned or maximized. Remarkably, the interaction can be strong enough to prevent the polymers to be pulled apart without breaking them.

Two different polymeric gels are brought in contact, and the cyclodextrins (yellow) bind to adamantane residues (green).

Molecular self-assembly is a well-known phenomenon at molecular scale in chemistry and biology. However, it had never been demonstrated at a macroscopic level. As Prof. Phil Gale from University of Southampton, UK, comments on Chemistry World, ‘Why didn’t anyone think of this earlier?’ Indeed.  This first demonstration can potentially result in many applications, particularly in the field of surface and membrane coating.

Additional material: Polymer blobs stuck with molecular velcro

Reference: A. Harada et al., Nature Chemistry 2010 DOI: 10.1038/nchem.893

In a recent article in Science, Pires et al. report a new lithographic method based on the local desorption of an organic resist by a heatable probe. A hot, sharp tip is employed as a nano-pen to scratch a surface covered by a layer of a polyphenolic compound. Repeating the process over and over again results in 3-dimensional patterns, and the obtained motif can be transferred to various substrates. For example, they started by carving the IBM logo, but then needed a more demanding task. They tackled the challenge offered by the well known Matterhorn shape. The nanomountain was carved into a 100 nm thick film after 120 separate steps. The model they created (picture below) stands 25 nanometers tall, which is 179′120′000′000 smaller than the 4478 meter high Matterhorn!

AFM scan of the replica of the Matterhorn written into the molecular glass

New methods for nanofabrication allowing to create functional structures are highly seeked, and research such as that presended here is promising, because it seems to be scalable to more practical uses.

On the live webcast visible on the Nobelprize website, the Prize announcement was followed by a live phone interview with Prof. Negishi. He let the audience know he was awaken at 5 in the morning by the phone call announcing him the good news, and that he just had time for a coffee before the interview took place. I imagine this was but the beginning of a very long day for him! Quite amusing was when a journalist asked Negishi about the impact of his discoveries for the human beings. At that, Negishi responded something like ‘Do you have any knowledge of Grignard chemistry?’ The journalist laughed before admitting that he had no clue about it, and Negishi explained the impact of carbon cross couplings in much simpler terms.

* Andre Geim is probably the first researcher to detain a Nobel Prize together with a Ig Nobel Prize, obtained in 2000 for levitating a frog with magnets.

The next day, I saw a talk from Luisa de Cola, who makes really nice looking assemblies of zeolithes with alternating colors (very recently reported in Angewandte), and one from Lee Cronin who, presented the concept of iChell (hope Apple did not protect the name) as inorganic chemical cell, made of large polyoxometallate compounds.

Self-assembly of “green” zeolite crystals and "red” crystals leads to highly regular crystal chains with strictly alternating colors. (reproduced from Schulte, B., Tsotsalas, M., Becker, M., Studer, A. and De Cola, L. , Angew. Chem. Int. Ed. doi: 10.1002/anie.201002851)

Wednesday was also the day of the Congress Party, that took place in the VIP area of the football stadium (the easyCredit Stadion) with a big buffet and unlimited drinks, human table football games, and fireworks. That was quite a party, and a very good time… I hope they put some pics on the congress website soon!

Today was the opening day, and thousands (really!) of chemists gathered in the huge congress center. The first -and only- talk I attended (due to a somewhat late arrival) was given by Prof. Klaus Müllen (from the Max Planck Institute for Polymer Research in Mainz). He quite impressively demonstrated how perfect graphene ribbons can be generated by bottom-up synthesis and subsequent reactions of benzene dendrimers (contrary to the method involving the peeling of graphite with tape). A very motivated and passionate speaker, he captivated his audience by showing amazing results, obtained by a careful design of a ‘core’ molecule, followed by its self-assembly into more complex structures.

This lecture was definitely a good start, and I’m looking forward to the next ones.

For more details:

Nature 2010, 466, 470-473 doi: 10.1038/nature09211

Advanced Materials, 2010. doi: 10.1002/adma.201001275

*I had to deal with my thesis writing & exam and some funding application stuff recently… and was close to an overdose of chemistry, hence my absence from the web.

Cloud whitening (SRM)

This concept, imagined by Stephan Salter from the University of Edinburgh, consists in spraying seawater in the atmosphere to increase reflectiveness of clouds. The clouds, produced by a fleet of around 1500 unmanned ships, would reflect more radiation from the earth. However, such an operation could have unexpected -and difficult to modelize- effects on oceanic climates and streams.

Covering the deserts with white films (SRM)

According to Alvia Gaskill who proposed this solution, covering a large enough area of the earth (first candidates would be Sahara, arabic and gobi deserts) could be expected to offset some or all of the projected additional radiative forcing and global warming from 2010 to 2070. Together with tremendous costs, ecological consequences such as perturbation of the atmospheric circulation (which could result in sub-saharian monsoon perturbation) must be feared.

Space sunshade (SRM)

Basically, this concept proposed by Roger Angel (University of Arizona), involves the use of trillions of small umbrellas, that would be put in orbit an stop some sunlight from reaching the Earth. If small 1 gram, 60 cm diameter discs were used, 800 000 of them would have to be sent every… minute, for 30 … years, in order to decrease the radiation hitting our planet of 1.8%.

Stratospheric sulfate aerosols (SRM)

Inspired by the eruption of Mount Pinatubo in 1991, which projected tons of particles in the atmosphere, and noticeably cooled the global temperatures of 0.5°C, chemistry Nobel Prize 1995 Paul J. Crutzen suggested the injection of sulfur compounds in the atmosphere. But this project could perturbate water cycles, the stratospheric ozone chemistry and biological life, which make large scale experimentation somewhat unrealistic.

Ocean iron fertilization (CDR)

This method involves the seeding of ocean with iron in order to promote a phytoplankton bloom, which can remove carbon dioxide from the atmosphere. Again, several side-effects are to be expected, as well as an increased water acidification, and the creation of large zones depleted from oxygen (the more the algae ‘breath’, the less oxygen available for the other species).

Although geoengineering is a flourishing field (just try to enter it in wikipedia), many of its promises will probably come true too late (if at all) if one wants to reduce anthropogenic global warming and climate change… scientific creativity will have to find other ways to deal with climate modifications.

The team from University of California (UC) Berkeley, and the Lawrence Berkeley National Laboratory, led by Carolyn Bertozzi, adapted the methodology known as ‘click-chemistry‘ to the particular conditions required by ‘in vivo’ conditions. Indeed, the original ‘click’ procedures, developed by Barry Sharpless (2), involved the use of toxic copper catalysts. In their article, the authors use a copper-free click reaction to label glycans – sugars particularly abundant on the surface of cells, where they are active in cell activity signalling, as well as in response to infections – which are thought of as appealing target for molecular imaging inside living organisms.

The first step involved the injection of azide-containing sugar derivatives, which are known to metabolically label glycans with the azide function. Then, a purposedly designed molecule carrying a signalling unit as well as a function reactive towards azides, had to be injected. The click reaction proceeded and as a result, glycans could be labeled in vivo, which paves the way for future specific biomolecule labeling inside living organisms.

Click chemistry inside a mouse (reproduced from ref. 1)

References:
(1) Pamela V. Chang, Jennifer A. Prescher, Ellen M. Sletten, Jeremy M. Baskin, Isaac A. Miller, Nicholas J. Agard,
Anderson Lo, and Carolyn R. Bertozzi, “Copper-free click chemistry in living animals”, Proc. Natl. Acad. Sci. USA, published online before print January 14, 2010. doi:10.1073/pnas.0911116107

(2) H. C. Kolb, M. G. Finn and K. B. Sharpless “Click Chemistry: Diverse Chemical Function from a Few Good Reactions”, Angew. Chem., Int. Ed. 2001, 40 2004–2021. doi:10.1002/1521-3773(20010601)40:11<2004::AID-ANIE2004>3.0.CO;2-5