A research team led by Hokkaido University in Japan have constructed a porous material that is very stable and changes color when exposed to acid vapor. This is believed to be the first reported instance of a hydrogen-bonded organic framework changing color in response to acid. The findings are described in the Journal of the American Chemical Society.
Chemists are working to develop porous materials made from organic molecules that have structures with well-defined openings that can separate and store gasses. Such materials can also be used in electronic devices and sensors.
In particular, researchers are investigating how to make materials using molecules bonded together by hydrogen bonds, known as hydrogen-bonding organic frameworks (HOFs). HOFs are high-crystalline, flexible, and regenerable, which make them attractive candidates. But they can also be fragile and crumble apart.
Ichiro Hisaki, a chemist at Hokkaido University's Research Institute for Electronic Science, along with Anderrazzak Douhal, a photophysicist at University of Castilla La Mancha, Spain and their colleagues developed a hexagon-shaped framework, called CPHATN-1a, and found a surprising attribute - it changes color from yellow to reddish-brown when exposed to acid solution or acid vapor.
When the acid solution or vapor is removed, either through heating or ambient evaporation, the HOF reverted back to its original yellow color.
The researchers determined that the color change is caused by protons adding onto nitrogen atoms within the compound, which shifts the spectrum of light absorbed.
Additional tests revealed that CPHATN-1a is extremely stable, maintaining its porous structure at temperatures to at least 633 Kelvin (359 C).
The robust material also stood up to heated, common organic solvents, including chloroform, ethanol and water, retaining its structure rather than dissolving or breaking apart.
"The present results would open a door to develop new porous materials with stimuli responsiveness," the researchers note. "These could be used in the creation of new sensors or towards the visualization of minute chemical reactions."
Tyler Tannert | EurekAlert!
A remote control for neurons
04.06.2020 | College of Engineering, Carnegie Mellon University
Smart textiles made possible by flexible transmission lines
03.06.2020 | Ecole Polytechnique Fédérale de Lausanne
Humans rely dominantly on their eyesight. Losing vision means not being able to read, recognize faces or find objects. Macular degeneration is one of the major...
In meningococci, the RNA-binding protein ProQ plays a major role. Together with RNA molecules, it regulates processes that are important for pathogenic properties of the bacteria.
Meningococci are bacteria that can cause life-threatening meningitis and sepsis. These pathogens use a small protein with a large impact: The RNA-binding...
An analysis of more than 200,000 spiral galaxies has revealed unexpected links between spin directions of galaxies, and the structure formed by these links...
Two prominent X-ray emission lines of highly charged iron have puzzled astrophysicists for decades: their measured and calculated brightness ratios always disagree. This hinders good determinations of plasma temperatures and densities. New, careful high-precision measurements, together with top-level calculations now exclude all hitherto proposed explanations for this discrepancy, and thus deepen the problem.
Hot astrophysical plasmas fill the intergalactic space, and brightly shine in stellar coronae, active galactic nuclei, and supernova remnants. They contain...
In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".
Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...
19.05.2020 | Event News
07.04.2020 | Event News
06.04.2020 | Event News
05.06.2020 | Life Sciences
05.06.2020 | Physics and Astronomy
05.06.2020 | Life Sciences