Chemistry news and discussions

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A special camera that can 'see' the intimate details of the helium-3 universe
https://phys.org/news/2022-05-special-c ... verse.html
by Bob Yirka , Phys.org
A team of physicists at Lancaster University has developed a camera system that can be used to capture the shadow of a sample of helium-3. In their paper published in the journal Physical Review B, the group describes their camera, their technique for using it and possible uses for the images it captures.

Helium-3 has particular interest for physicists due to its interesting internal structure, which some in the field have described as the "universe in a droplet." One of its properties is that it transitions to a superfluid when chilled to extremely low temperatures. As part of research efforts, physicists have found ways to detect it by using special probes to sense its weak magnetic field. They have found ways to "touch" it by pushing things through samples of it and measuring their impact. They have also discovered that it is possible to hear some of its characteristics using special microphones. In this new effort, the researchers have now developed a way to visualize it with a special camera system.
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New light-powered catalysts could aid in manufacturing
https://phys.org/news/2022-05-light-pow ... s-aid.html
by Anne Trafton, Massachusetts Institute of Technology

Chemical reactions that are driven by light offer a powerful tool for chemists who are designing new ways to manufacture pharmaceuticals and other useful compounds. Harnessing this light energy requires photoredox catalysts, which can absorb light and transfer the energy to a chemical reaction.

MIT chemists have now designed a new type of photoredox catalyst that could make it easier to incorporate light-driven reactions into manufacturing processes. Unlike most existing photoredox catalysts, the new class of materials is insoluble, so it can be used over and over again. Such catalysts could be used to coat tubing and perform chemical transformations on reactants as they flow through the tube.

"Being able to recycle the catalyst is one of the biggest challenges to overcome in terms of being able to use photoredox catalysis in manufacturing. We hope that by being able to do flow chemistry with an immobilized catalyst, we can provide a new way to do photoredox catalysis on larger scales," says Richard Liu, an MIT postdoc and the joint lead author of the new study.
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New method allows easy, versatile synthesis of lactone molecules

by The Scripps Research Institute
https://phys.org/news/2022-05-method-ea ... ctone.html
Chemists at Scripps Research have unveiled a method for turning cheap and widely available chemicals known as dicarboxylic acids into potentially very valuable molecules called lactones.

Lactone structures are common in biologically active natural molecules; they can be found, for example, in vitamin C and in the bacterial-derived antibiotic erythromycin. Chemists have long had techniques for synthesizing lactones, but these techniques are quite limited in what they can produce. The achievement, reported May 26, 2022, in Science, makes the construction of diverse, complex lactones easier than ever.

"This method should be very broadly useful for developing new pharmaceuticals, polymer materials, perfumes and many other chemical products—we're already getting queries from interested manufacturers," says Jin-Quan Yu, Ph.D., the Frank and Bertha Hupp Professor of Chemistry at Scripps Research.

Yu and his laboratory are renowned for their innovations in molecule building, especially with regard to "C-H activation." This involves the use of specially designed catalyst molecules to remove a hydrogen (H) atom from a carbon (C) atom on an organic molecule, and to replace the hydrogen atom with a more complex cluster of atoms.
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Cross-coupling ketones: Adding flexibility to the synthetic chemistry toolbox
https://phys.org/news/2022-05-cross-cou ... hetic.html
by Institute of Chemical Research of Catalonia
Researchers have published a paper describing, for the first time, the use of ketones as alkyl cross-coupling synthons.

For Xin-Yang Lv and Dr. Roman Abrams, researchers in Prof. Martin's group at the Institute for Chemical Research of Catalonia (ICIQ), keeping up with scientific literature is a source of inspiration for the development of new synthetic methodologies. Taking a recent publication one step further, the scientists in Prof. Martín's group have devised a new strategy that facilitates the creation of organic molecules of pharmacological interest. The method has been published in the open-access journal Nature Communications.

The strategy developed by the Martin group makes ketones available to chemists to be used as alkyl cross-coupling synthons. "This method provides an enormous flexibility to chemists and pharmacists in the synthesis of organic molecules, by moving beyond the classical reactivity of ketones and towards the use of this abundant class of compound as cross-coupling partners," explains Prof. Ruben Martin, leader of a research group at ICIQ and ICREA professor.
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Experiments in twisted, layered quantum materials offer new picture of how electrons behave
https://phys.org/news/2022-06-layered-q ... trons.html
by Princeton University
A recent experiment detailed in the journal Nature is challenging our picture of how electrons behave in quantum materials. Using stacked layers of a material called tungsten ditelluride, researchers have observed electrons in two-dimensions behaving as if they were in a single dimension—and in the process have created what the researchers assert is a new electronic state of matter.

"This is really a whole new horizon," said Sanfeng Wu, assistant professor of physics at Princeton University and the senior author of the paper. "We were able to create a new electronic phase with this experiment—basically, a new type of metallic state."

Our current understanding of the behavior of interacting electrons in metals can be described by a theory that works well with two- and three-dimensional systems, but breaks down when describing the interaction of electrons in a single dimension.

"This theory describes the majority of the metals that we know," said Wu. "It states that electrons in metal, though strongly interacting, should behave like free electrons, except that they may have different values in some characteristic quantities, such as the mass and magnetic moment."
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New method helps exfoliate hexagonal boron nitride nanosheets
https://phys.org/news/2022-06-method-ex ... tride.html
by Chinese Academy of Sciences
Chinese researchers recently reported an innovative mechanical process for controllably exfoliating hexagonal boron nitride nanosheets (h-BNNSs).This method, known as the "water-icing triggered exfoliation process," was proposed by Prof. Zhang Junyan's group from the Lanzhou Institute of Chemical Physics (LICP) of the Chinese Academy of Sciences (CAS).

h-BNNSs, with a honeycomb-like structure similar to graphene, show excellent chemical and physical properties, such as high thermal conductivity, good resistance to oxidation, remarkable mechanical strength, a low dielectric constant, outstanding lubricity, excellent biocompatibility, and optical properties.

Given these characteristics, h-BNNSs are promising materials for various applications, including high-performance electronic devices, dielectric substrates, thermal management, lubrication, sensors, catalysts, and sorbents. As a result, developing a simple, controllable, and scalable method to produce high-quality h-BNNSs for commercial applications is an urgent need.
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Scientists serendipitously discover rare cluster compound
https://phys.org/news/2022-06-scientist ... pound.html
by Kyoto University
Scientists at Kyoto University's Institute for Cell-Material Sciences have discovered a novel cluster compound that could prove useful as a catalyst. Compounds, called polyoxometalates, that contain a large metal-oxide cluster carry a negative charge. They are found everywhere, from anti-viral medicines to rechargeable batteries and flash memory devices.

The new cluster compound is a hydroxy-iodide (HSbOI) and is unusual, as it has large, positively charged clusters. Only a handful of such positively charged cluster compounds have been found and studied.

"In science, the discovery of new material or molecule can create a new science," says Kyoto University chemist Hiroshi Kageyama. "I believe that these new positively charged clusters have great potential."

The first metal oxide cluster was discovered in 1826. Chemists have since synthesized hundreds of compounds with negatively charged clusters, which have properties useful in magnetism, catalysis, ionic conduction, biological applications and quantum information. Their properties make them useful in diverse fields from catalysis to medicine and chemical synthesis.

In more recent years, scientists have focused their attention on synthesizing compounds with positively charged clusters and learning their properties.
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Structure-property relationships in nanoporous and amorphous iridium oxides
https://phys.org/news/2022-06-structure ... idium.html
by Yonsei University
South Korean-based researchers have used first-principles quantum mechanical simulations to better understand the structure-property relationships in various polymorphic phases of iridium oxides to elucidate their outstanding performance in catalyzing the oxygen evolution reaction (OER). The OER is an important half-cell reaction where water is catalytically split to evolve oxygen. However, due to the intrinsic sluggish kinetics of the OER, this leads to an overall poor catalytic performance in general.

The latest findings from computational materials scientist, Professor Aloysius Soon and his team from the Department of Materials Science & Engineering at Yonsei University, demonstrate new physiochemical insights into how nonequivalent connectivity in the amorphous structures strongly enhances the flexibility of the charge states of the iridium cations, and hence promotes the presence of electrophilic oxygens in them, as compared to their crystalline counterparts. As Professor Soon writes in Nature Communications: "A fundamental atomic-scale understanding of high-performance nanopore-containing amorphous oxides of iridium is still very much lacking. And it greatly hinders the establishment of a design rule for further performance improvement."
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Study finds evidence of resonant Raman scattering from surface phonons of Cu(110)
https://phys.org/news/2022-06-evidence- ... onons.html
by Ingrid Fadelli , Phys.org
Researchers at Johannes Kepler University in Linz have been investigating the physical properties of Cu(110), a surface attained when cutting a single copper crystal in a specific direction, for several years. Their most recent study, featured in Physical Review Letters, provides the first evidence of so-called resonant Raman scattering from the surface of the metal. This phenomenon entails the inelastic scattering of phonons by matter.

"We have already done a lot of research on Cu(110), and are particularly interested in the surface state transition at 2.1 eV. Because the surface state electrons are confined to the first few layers of the crystal, the Cu(110) surface state is a sensitive measure of the condition of the surface. We use this high sensitivity to study various physical processes at the surface, such as reconstruction of the surface after adsorption or molecular growth," Mariella Denk, one of the researchers who carried out the study, told Phys.org.

"In the course of discussions with Prof. Dr. Norbert Esser's group in Berlin, which mainly deals with Raman scattering from semiconductors but also has experience in studying metal surfaces, we came up with the idea of simply trying to see if Raman scattering from surface phonons could be seen on Cu(110)."
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Microporous polymer membranes for light-gated ion transport
https://phys.org/news/2022-06-microporo ... d-ion.html
by Thamarasee Jeewandara , Phys.org
In a new report now published in Science Advances, Zongyao Zhou and a team of scientists in chemical engineering and physical science and engineering at the King Abdullah University of Science and Technology in Saudi Arabia developed an artificial light-gated ion channel membrane using conjugated microporous polymers. The team was inspired by light-gated ion channels in cell membranes that play an important role in many biological activities to precisely regulate the membrane pore size and thickness at the molecular level via bottom-up design and electropolymerization methods. The process led to reversible "on/off" light control for light-gated ion transport across the membrane to deliver hydrogen, potassium, sodium, lithium, calcium, magnesium and aluminum ions.

Light-gated membranes for ion transport

Light-gated ion channels can regulate the transport of ions in living cells to adjust electrical excitability, calcium influx, and other crucial cellular processes. At present, channelrhodopsins are the first and only class of light-gated ion channels identified in biology, and they have received much attention in recent years. The direct use of light-gated channelrhodopsins are limited by the generally minimal chemical and physical stability of the proteins in external environments. Researchers have therefore conducted extensive studies to develop artificial light-gated ion channels for applications across neurobiology, bioelectronics and waste purification.
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