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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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.