"Chemical activation of carbon dioxide, meaning its cleavage in a chemical reaction," explain chemists Goettmann, Thomas and Antonietti, " is one of the biggest challenges in synthetic chemistry." The bonds in this molecule are very stable, so a lot of energy is needed to split them. To date, only a few special metal catalysts are known to be capable of breaking the C–O bonds in CO2.
In contrast to most previous approaches, Antonietti’s team worked with metal-free catalysts, turning toward plants for inspiration. Photosynthesis in modern green plants involves an important intermediate step: the bonding of CO2 to nitrogen atoms to form carbamates. The German researchers thus also experimented with nitrogen-rich catalysts with structures that allow them to form carbamates. Their new class of catalysts is made of flat, graphite-like layers. The individual layers consist of ring systems involving carbon and nitrogen atoms. This porous material, called graphitic carbon nitride, is very heat-stable and, although it enters into many chemical interactions, it is so stable that it nearly always re-forms—an ideal catalyst. It can even be used to activate carbon dioxide. It was thus possible to oxidize benzene (an aromatic six-membered carbon ring) to phenol (which has an additional OH group). The by-product of the reactio n is carbon monoxide (CO), which can be used directly for chemical syntheses.
From a purely formal point of view, this reaction cleaves the CO2 into an oxygen diradical and CO. However, like photosynthesis, the reaction seems to occur by way of carbamates: In the first step, CO2 binds to individual free amino groups present in the carbon nitride. It then oxidizes the benzene to phenol, and in the end the highly desirable CO separates from the catalyst. "This could make novel, previously unknown chemistry of CO2 accessible," hopes Antonietti. "It may even be the first step in artificial photosynthesis."
Source:John Wiley & Sons, Inc.
Related biology news :
1. Bevacizumab Combined With Chemotherapy Improves Progression-Free Survival for Patients With Advanced Breast Cancer
2. AIDS Public Awareness Campaign Expands Following Report Of Rapidly Progressive HIV
3. Progress on HIV/AIDS significant but insufficient
4. Progress being made in exploring potential use of stem cells to treat heart disease
5. Progress made in HIV vaccine development
6. Unchecked DNA replication drives earliest steps toward cancer
7. Virologists make major step towards understanding the process of HIV infection
8. Moffitt-USF head toward first human trials of anti-cancer drug that targets protein AKT
9. Cats indifference towards sugar explained
10. A step toward the $1,000 personal genome using readily available lab equipment
11. A new step towards an AIDS vaccine