Chemistry news and discussions

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Laser writing may enable 'electronic nose' for multi-gas sensor
https://phys.org/news/2022-06-laser-ena ... i-gas.html
By Ashley J. WennersHerron, Pennsylvania State University
Environmental sensors are a step closer to simultaneously sniffing out multiple gases that could indicate disease or pollution, thanks to a Penn State collaboration. Huanyu "Larry" Cheng, assistant professor of engineering science and mechanics in the College of Engineering, and Lauren Zarzar, assistant professor of chemistry in Eberly College of Science, and their teams combined laser writing and responsive sensor technologies to fabricate the first highly customizable microscale gas sensing devices.

They published their technique this month in ACS Applied Materials & Interfaces.

"The detection of gases is of critical importance to various fields, including pollution monitoring, public safety assurance and personal health care," Cheng said. "To fill these needs, sensing devices must be small, lightweight, inexpensive and easy to use and apply to various environments and substrates, such as clothing or piping."
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Team creates first ever VX neurotoxin detector
https://phys.org/news/2022-07-team-vx-n ... ector.html
by City College of New York
City College of New York associate professor of physics Ronald Koder and his team at the Koder Lab are advancing the field of molecular detection by developing the first proteins that can detect a deadly nerve agent called VX in real-time and without false positives from insecticides.

VX is classified as a neurotoxin and an incredibly deadly chemical warfare agent that has been used in assassinations by some nations. It can cause permanent brain damage in those who survive exposure.

These potentially life-saving findings are published in the July 2022 edition of Science Advances, with lab member Jim McCann serving as the paper's primary author. It outlines the design of two proteins that detect the neurotoxin by changing their shape in the presence of VX.

In collaboration with Douglas Pike and Vikas Nanda at Rutgers University, the CCNY team used a protein design program called ProtCAD to design 20 different proteins. According to Koder, the computer code was new and unlike anything the team had previously worked with, so it came as a bit of a surprise that two of their protein designs worked rather quickly.

"Having the first thing we tried with a small molecule actually just work was pretty great," Koder said. "In that absence of VX, all of the negative charges repel each other and then the protein unfolds. And it really extends, almost like a stick. When the protein binds VX it wraps all the way around the molecule becoming much more compact."
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Chemists find a contrary effect: How diluting with water makes a solution firm
https://phys.org/news/2022-07-chemists- ... ution.html
by Eindhoven University of Technology
In Science, TU/e researchers have published their study on new phase transitions of solutions and gels in water, which seem to go against the basic principles of chemistry, and which they discovered by accident.

In chemistry, a hydrogel changes to a liquid by diluting it with water. For the reverse transition, you increase the hydrogel concentration. However, TU/e researchers led by Bert Meijer accidentally discovered that their liquid solution turned into a hydrogel when diluted. This phenomenon hadn't been researched or described before and could have consequences in many areas in chemistry and biology.

The research focuses on the formation of certain hydrogels. This means that it starts with an aqueous solution of, in this case, two substances (a surfactant and a monomer). The research shows that a gel is formed at a specific ratio of these two substances in water. This gel is formed by long, supramolecular networks composed of both substances. The amounts of these substances in water (the concentrations) also determine where the phase transition of the gel formation is located. When decreasing the concentration without changing the ratio between the two components, the gel dissolves and becomes liquid. So far, this is familiar territory.
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Designing surfaces that make water boil more efficiently
https://phys.org/news/2022-07-surfaces-efficiently.html
by David L. Chandler, Massachusetts Institute of Technology
The boiling of water or other fluids is an energy-intensive step at the heart of a wide range of industrial processes, including most electricity generating plants, many chemical production systems, and even cooling systems for electronics.

Improving the efficiency of systems that heat and evaporate water could significantly reduce their energy use. Now, researchers at MIT have found a way to do just that, with a specially tailored surface treatment for the materials used in these systems.

The improved efficiency comes from a combination of three different kinds of surface modifications, at different size scales. The new findings are described in the journal Advanced Materials in a paper by recent MIT graduate Youngsup Song Ph.D. '21, Ford Professor of Engineering Evelyn Wang, and four others at MIT. The researchers note that this initial finding is still at a laboratory scale, and more work is needed to develop a practical, industrial-scale process.
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Two-dimensional ionic liquids to effectively capture carbon dioxide
https://phys.org/news/2022-07-two-dimen ... pture.html
by Chinese Academy of Sciences
In the context of global concerns about climate change and greenhouse gas control, a new technology for CO2 capture, utilization, and storage has attracted broad attention.

Ionic liquids, composed of only cations and anions, are considered a new type of CO2 adsorbent due to their ultralow vapor pressure and environmentally friendly features.

Recently, a group led by Profs Zhang Suojiang and He Hongyan from the Institute of Process Engineering (IPE) of the Chinese Academy of Sciences (CAS) has found that two-dimensional ionic liquids show a completely different melting behavior than when in bulk phase, leading to a high CO2 adsorption capacity and structural robustness during the CO2 adsorption-desorption process.

This study was published in Cell Reports Physical Science on July 12.

The researchers found that ionic liquids can form a two-dimensional-monolayer, ordered, checkerboard structure when supported by a metal surface. The two-dimensional ionic liquids exhibited anomalous stepwise melting processes, involving localized-rotated, out-of-plane-flipped, and fully disordered states, rather than the single melting point for the bulk ionic liquids.

"Anions and cations are arranged together in a checkerboard manner, thus forming a two-dimensional, ordered Z-bond network. This makes it more likely for the multi-step melting behaviors such as ionic rotation and flip," said Prof. He.
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Chemists change the bonds between atoms in a single molecule for the first time
https://phys.org/news/2022-07-chemists- ... ecule.html
by Bob Yirka , Phys.org
A team of researchers from IBM Research Europe, Universidade de Santiago de Compostela and the University of Regensburg has changed the bonds between the atoms in a single molecule for the first time. In their paper published in the journal Science, the group describes their method and possible uses for it. Igor Alabugin and Chaowei Hu, have published a Perspective piece in the same journal issue outlining the work done by the team.

The current method for creating complex molecules or molecular devices, as Alagugin and Chaowei note, is generally quite challenging—they liken it to dumping a box of Legos in a washing machine and hoping that some useful connections are made. In this new effort, the research team has made such work considerably easier by using a scanning tunneling microscope (STM) to break the bonds in a molecule and then to customize the molecule by creating new bonds—a chemistry first.
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Promising evidence of deuterium forming into a metallic state at high pressure
https://phys.org/news/2022-07-evidence- ... -high.html
by Bob Yirka , Phys.org
A trio of researchers at the French Alternative Energies and Atomic Energy Commission has shown promising evidence of deuterium forming into a metallic state at high pressure. In their paper published in the journal Physical Review Letters, Paul Loubeyre, Florent Occelli, and Paul Dumas describe the process they used to pressurize a deuterium sample and test it for a transition state.

Theory suggests that all elements should transition to a metallic state if subjected to strong enough pressure. This is because at some point, their electrons will become delocalized. But modeling, much less demonstrating, such transition points has proven to be difficult. Early research looking for the transition state of hydrogen led to theories that it would reach a metallic state when hydrogen molecules disassociated completely. That led to many efforts to see if such theories were true—sadly, none were successful. Then in 2000, a team at Cornell University calculated that hydrogen should transition at 410 GPa. In 2020, the researchers of the current study used a diamond anvil cell to compress a sample of hydrogen to 425 GPa and used synchrotron infrared absorption and Raman spectroscopy to measure the band gap of the material. They found a sudden drop from 0.6eV to 0.1eV at 80K, comprising promising evidence of hydrogen forming into a metallic state as theorized.
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Concise synthesis of pleurotin developed
https://phys.org/news/2022-08-concise-s ... rotin.html
by Wendy Plump, Princeton University
From the perspective of chemists, pleurotin is an intriguing molecule.

There is strong evidence of untapped therapeutic properties as a tumor inhibitor and antibiotic. It has a fascinating complex structure (six rings! eight stereocenters!). And it has been difficult to synthesize over the decades. The last time chemists pulled that off, the year was 1988 and they needed 26 steps in which to do it.

For Princeton Chemistry's Sorensen Lab, those qualities were part of the attraction for a long-term investment of time and energy that has come to fruition.

The lab reports a concise synthesis of pleurotin by way of the Diels-Alder reaction and a radical epimerization that flips a cis-hydrindane to the desired trans-hydrindane. Their late-stage intermediate intersects the milestone 1988 synthesis towards the end of the process, thereby reducing the total number of steps needed for the synthesis by thirteen.

The lab's process could yield an expanded family of pleurotin-like anticancer screening candidates which, down the line, may be useful to pharmaceutical companies looking to exploit the promise of pleurotin as a next-generation drug.
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Miniaturized lab-on-a-chip for real-time chemical analysis of liquids
https://phys.org/news/2022-08-miniaturi ... lysis.html
by Vienna University of Technology
In analytical chemistry, it is often necessary to accurately monitor the concentration change of certain substances in liquids on a time scale of seconds. Especially in the pharmaceutical industry, such measurements need to be extremely sensitive and reliable.

A new type of sensor has been developed at TU Wien which is highly suitable for this task and combines several important advantages in a unique way: based on customized infrared technology, it is significantly more sensitive than previous standard devices. Moreover, it can be used for a wide range of molecule concentrations and it can operate directly in the liquid. This is the consequence of its chemical robustness and thus provides data in real time, i.e. within fractions of a second. These results have now been published in Nature Communications.

Different molecules absorb different wavelengths

"To measure the concentration of molecules, we use radiation in the mid-infrared spectral range," says Borislav Hinkov, head of the research project from the Institute of Solid State Electronics at TU Wien. This is a well-known technique: molecules absorb specific wavelengths in the mid-infrared range, while other wavelengths are transmitted without attenuation. Thus, different molecules have their very specific "infrared fingerprint." By accurately measuring the wavelength-dependent absorption strength profile, it is possible to determine the concentration of a particular molecule in the sample at any given time.
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2D lattice-confined Cu atoms enable room-temperature methane conversion
https://phys.org/news/2022-08-2d-lattic ... nable.html
by Li Yuan, Chinese Academy of Sciences

Methane, as the main component of shale gas, natural gas and combustible ice, is among the most promising energy resources for producing high-value chemicals. However, it is still challenging to activate methane under mild conditions due to the high symmetry and low polarizability of methane molecules.

Recently, a research group led by Prof. Deng Dehui and Assoc. Prof. Yu Liang from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) achieved highly efficient room-temperature methane conversion to liquid C1 oxygenates over ultrathin two-dimensional (2D) Ru nanosheets with lattice-confined Cu atoms.

This study was published in Chem Catalysis on August 24.

Ultrathin 2D metallic nanosheets are promising matrix materials for creating active centers for the methane activation by confining heteroatoms in the lattice. However, the hardly controllable tailoring of the coordination environment for the confined heteroatoms in the 2D nanosheets makes it challenging for the construction of effective active sites for methane activation.
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