The building blocks of rationally designed chemicals are simple elements: carbon, hydrogen, oxygen and so on. These elements can be combined in myriad ways to accomplish a variety of chemicals with different characteristics. Even the same chemical can be treated differently - with pressure or heat, for example - to show drastically different properties. A simpler version is to think of how water can be boiled to cook pasta or frozen to become ice - the same ingredient can be made into two different states via temperature treatment.
Now, researchers are working to better control how the chemicals respond to treatment, as well as how to reverse the chemicals back to their original state with little to no interference. Such control would allow scientists to prepare the sensing systems of environmental stimuli, as well as continuously repeat the sensing.
The two-component dye shows self-recovering mechanochromic luminescence that exhibits a high-contrast emission color change between violet and orange.
Credit: Yokohama National University
A team of researchers at Yokohama National University has achieved such results with a specific compound that can emit light and has potential applications in the next generation of smart devices such as wearable devices and anti-counterfeiting paintings. They published their results online on September 12, ahead of print in Chemical Communications.
The compound is a derivative of thiophene, which is a dye with mechanochromic luminescence properties -- it changes color under physical change. It starts emitting a violet glow under the irradiation of UV light, but as it is exposed to mechanical stimuli, such as grinding, the violet glow shifts slightly to blue. Another external intervention can make the compound heal and become violet again.
"Mechanochromically luminescent (MCL) dyes have recently attracted considerable interest on account of their potential applications," said Suguru Ito, paper author and associate professor in the Department of Chemistry and Life Science in the Graduate School of Engineering Science at Yokohama National University. "However, it is still very difficult to rationally design MCL dyes with desired characteristics."
In this study, however, researchers discovered that by adding another chemical called DMQA, the dye changed to orange under mechanical stimuli. The dye did not need more external stimuli to revert back to violet either.
"We combined two kinds of rational design guidelines for tuning the luminescent properties, resulting in the desired -- and unprecedented-- characteristics of high-contrast, self-recovering dyes," Ito said.
The first rational design guideline is that the recovery behavior of the dye can be attributed to the length of the alkyl group in the compound -- a longer chain of carbon atoms with hydrogens in the dye allows the dye to recrystallize and heal in time. The second is that by mixing with DMQA, the color range between the original state and ground state differ greatly.
"The next step is to establish a rational design guideline to control the dye's responsiveness to mechanical stimuli," Ito said. "My ultimate goal is to develop an innovative pressure-sensing system by rationally creating a material that can change its emission color in stages in response to mechanical stimuli of different intensity."
With such control, Ito could use mechanical stimuli to precisely induce a specific and intended response. A little pressure could shift the violet glow to blue, a little more pressure pushes the glow closer to red. A system with such ability would allow for stepwise changes and recoveries by the stimulus, which could be highly beneficial in the next generation of smart materials, according to Ito.
Minako Ikeya and Genki Katada, both of the Department of Chemistry and Life Science in the Graduate School of Engineering Science at Yokohama National University, also authored the paper.
This work was supported in part by the Japan Society for the Promotion of Science KAKENHI Grant Number 18H04508 in Grant-in-Aid for Scientific Research on Innovative Areas "Soft Crystals: Area No. 2903".
Yokohama National University (YNU or Yokokoku) is a Japanese national university founded in 1949. YNU provides students with a practical education utilizing the wide expertise of its faculty and facilitates engagement with the global community. YNU's strength in the academic research of practical application sciences leads to high-impact publications and contributes to international scientific research and the global society.
For more information, please see: https:/
Akiko Tsumura | EurekAlert!
Theoretical tubulanes inspire ultrahard polymers
14.11.2019 | Rice University
New spin directions in pyrite an encouraging sign for future spintronics
14.11.2019 | ARC Centre of Excellence in Future Low-Energy Electronics Technologies
The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden has succeeded in using Selective Electron Beam Melting (SEBM) to...
Carbon nanotubes (CNTs) are valuable for a wide variety of applications. Made of graphene sheets rolled into tubes 10,000 times smaller than a human hair, CNTs have an exceptional strength-to-mass ratio and excellent thermal and electrical properties. These features make them ideal for a range of applications, including supercapacitors, interconnects, adhesives, particle trapping and structural color.
New research reveals even more potential for CNTs: as a coating, they can both repel and hold water in place, a useful property for applications like printing,...
If you've ever tried to put several really strong, small cube magnets right next to each other on a magnetic board, you'll know that you just can't do it. What happens is that the magnets always arrange themselves in a column sticking out vertically from the magnetic board. Moreover, it's almost impossible to join several rows of these magnets together to form a flat surface. That's because magnets are dipolar. Equal poles repel each other, with the north pole of one magnet always attaching itself to the south pole of another and vice versa. This explains why they form a column with all the magnets aligned the same way.
Now, scientists at ETH Zurich have managed to create magnetic building blocks in the shape of cubes that - for the first time ever - can be joined together to...
Quantum-based communication and computation technologies promise unprecedented applications, such as unconditionally secure communications, ultra-precise...
In two experiments performed at the free-electron laser FLASH in Hamburg a cooperation led by physicists from the Heidelberg Max Planck Institute for Nuclear physics (MPIK) demonstrated strongly-driven nonlinear interaction of ultrashort extreme-ultraviolet (XUV) laser pulses with atoms and ions. The powerful excitation of an electron pair in helium was found to compete with the ultrafast decay, which temporarily may even lead to population inversion. Resonant transitions in doubly charged neon ions were shifted in energy, and observed by XUV-XUV pump-probe transient absorption spectroscopy.
An international team led by physicists from the MPIK reports on new results for efficient two-electron excitations in helium driven by strong and ultrashort...
15.11.2019 | Event News
15.11.2019 | Event News
05.11.2019 | Event News
15.11.2019 | Power and Electrical Engineering
15.11.2019 | Power and Electrical Engineering
15.11.2019 | Ecology, The Environment and Conservation