Single step process transforms carbon dioxide into star-shaped molecules that are promising building blocks for useful polymeric materials.
The power of carbon dioxide has been harnessed by Singapore's Agency for Science, Technology and Research (A*STAR) researchers to make two symmetrical star-shaped molecules in a single step.  These molecules could be used to build complex, functional polymeric materials useful for catalysis, coatings and drug delivery.
Carbon dioxide is a useful feedstock gas for synthesis of complex, functional materials. © 2016 A*STAR Institute of Materials Research and Engineering
Carbon dioxide is a cheap and accessible base material, explains lead researcher He-Kuan Luo from the A*STAR Institute of Materials Research and Engineering. “Therefore, many people are searching for efficient methods to transform carbon dioxide into useful molecules,” he explains. “But transforming carbon dioxide is not typically easy.”
His team has developed a simple route to use carbon dioxide to make aromatic compounds that can be used as building blocks for more complicated materials. They created symmetrical benzene rings with three or six identical arms comprising carbonate groups terminated by carbon–carbon triple bonds, or ‘alkynes’. “We can integrate the carbon dioxide into the molecule without the need for high temperatures or high pressure,” says Luo.
The molecules were made in a single step. The team introduced carbon dioxide from dry ice to an alcohol with an alkyne end group and benzene rings decorated with either three or six alkyl bromide groups. “At the beginning, however, only some of the branches reacted so we could not get the desired compound,” Luo explains.
The team fine-tuned the process and found the reactions worked most efficiently at room temperature, with the carbon dioxide at atmospheric pressure and with the addition of both a promoter tetrabutylammonium bromide (TBAB) and the base potassium carbonate. “We tried many times and after a few months, we finally got [the bromide groups in] all six branches to react [with the alcohol],” he says.
Adding the promoter to the mix doubled the product produced. “It is likely that the tetrabutylammonium cation enhances the rate of carbon dioxide incorporation by stabilizing the carbonate anion,” says Luo.
The reaction time is also vital. “We needed to be patient and let the reaction run to completion to ensure that all the branches reacted.” The synthesis of the three-armed and six-armed star-shaped molecule took two and four days respectively.
The alkynes on the end of each arm in these molecules should theoretically be able to react with a host of different molecules using simple click chemistry – to produce a range of complex or functional materials. “We are currently trying to use the six-armed branched molecule to build more functional star-shaped molecules, which may find applications in catalysis, coatings and drug delivery,” says Luo.
The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering
 Khoo, R. S. H., Lee, A. M. X., Braunstein, P., Hor, T. S. A. & Luo, H.-K. A facile one-step synthesis of star-shaped alkynyl carbonates from CO2. Chemical Communications 51, 11225–11228 (2015).
Original article from Agency for Science, Technology and Research
A*STAR Research | Research SEA
Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says
19.07.2018 | Purdue University
Machine-learning predicted a superhard and high-energy-density tungsten nitride
18.07.2018 | Science China Press
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences