Category: Chemistry

Re-using gold from electronic waste prevents it from being lost to landfill, and using this reclaimed gold for drug manufacture reduces the need to mine new materials. Current catalysts are often made of rare metals, which are extracted using expensive, energy-intensive and damaging mining processes.

The method for extracting gold was developed by researchers at the University of Cagliari in Italy and the process for using the recovered gold was developed by researchers at Imperial College London. The study is published in ACS Sustainable Chemistry & Engineering.

Waste electrical and electronic equipment (WEEE) is typically sent to landfill, as separating and extracting the components requires a lot of energy and harsh chemicals, undermining its economic viability. However, WEEE contains a wealth of metals that could be used in a range of new products.

Finding ways to recover and use these metals in a low-cost, low-energy and non-toxic way is therefore crucial for making our use of electronic goods more sustainable.

Lead researcher Professor James Wilton-Ely, from the Department of Chemistry at Imperial, said, “It is shocking that most of our electronic waste goes to landfill and this is the opposite of what we should be doing to curate our precious elemental resources. Our approach aims to reduce the waste already within our communities and make it a valuable resource for new catalysts, thereby also reducing our dependence on environmentally damaging mining practices.”

“We are currently paying to get rid of electronic waste, but processes like ours can help reframe this ‘waste’ as a resource. Even SIM cards, which we routinely discard, have a value and can be used to reduce reliance on mining and this approach has the potential to improve the sustainability of processes such as drug manufacture.”

Professors Angela Serpe and Paola Deplano, from the University of Cagliari, developed a low-cost way to extract gold and other valued metals from electronic waste such as printed circuit boards (PCBs), SIM cards and printer cartridges under mild conditions. This patented process involves selective steps for the sustainable leaching and recovery of base metals like nickel, then copper, silver and, finally, gold, using green and safe reagents.

However, the gold produced from this process is part of a molecular compound and so cannot be re-used again for electronics without investing a lot more energy to obtain the gold metal. Seeking a use for this compound of recovered gold, the team of Professor Wilton-Ely and his colleague, Professor Chris Braddock, investigated whether it could be applied as a catalyst in the manufacture of useful compounds, including pharmaceutical intermediates.

Catalysts are used to increase the rate of a chemical reaction while remaining unchanged and are used in most processes to produce materials. The team tested the gold compound in a number of reactions commonly used in pharmaceutical manufacture, for example for making anti-inflammatory and pain-relief drugs.

They found that the gold compound performed as well, or better, than the currently used catalysts, and is also reusable, further improving its sustainability.

The researchers suggest that making it economically viable to recover gold from electronic waste could create spin-off uses for other components recovered in the process. For example, in the process, copper and nickel are also separated out, as is the plastic itself, with all these components potentially being used in new products.

Sean McCarthy, the Ph.D. student leading the research in the lab at Imperial, said, “By weight, a computer contains far more precious metals than mined ore, providing a concentrated source of these metals in an ‘urban mine’.”

Professor Serpe said, “Research like ours aims to contribute to the cost-effective and sustainable recovery of metals by building a bridge between the supply of precious metals from scrap and industrial demand, bypassing the use of virgin raw materials.”

The teams are working to extend this approach to the recovery and re-use of the palladium content of end-of-life automotive catalytic converters. This is particularly pressing as palladium is widely used in catalysis and is even more expensive than gold.

More information: Sean McCarthy et al, Homogeneous Gold Catalysis Using Complexes Recovered from Waste Electronic Equipment, ACS Sustainable Chemistry & Engineering (2022). DOI: 10.1021/acssuschemeng.2c04092

Provided by Imperial College London 

A new paper published in Energy Material Advances explores Eu³⁺-Bi³⁺ codoping double perovskites for single-component white-light-emitting diodes.

“With lead-halide perovskites reaching a mature research stage approaching product marketing, concerns remain about the materials’ stability and the toxicity of lead-based salts,” said paper author Hongwei Song, professor at College of Electronic Science and Engineering, Jilin University.

Double perovskites with Cs₂AgInCl₆ composition, often doped with various elements, have been in the spotlight owing to their intriguing optical properties, namely, self-trapped exciton (STEs) emission and dopant-induced photoluminescence. This interest has sparked different synthesis approaches towards both crystals and nanocrystals, and the exploration of many alloy compositions with mono- and trivalent cations other than Ag⁺ and In³⁺.

Song explained that, in the development of lead-free perovskite materials, people’s first thought is to replace Pb element with a non-toxic element. In order to replace Pb in halide perovskite, researchers chose several low-toxic cations in the same period closest to it, such as Sn, Ge, Bi, Sb, In, etc., because they have a similar inactive shell s orbital.

This is the key to the unique photoelectric properties of perovskite materials. Lead-based perovskite materials have attracted great attentions in solid-state lighting area due to their high efficiency, high color rendering and tunable luminescence performance. This is both an opportunity and a challenge for the overall development of the photoelectric industry.

“Since the pioneering work on Cs₂AgInCl₆ in 2017 reported by Giustino et al. and Zhou et al. nearly simultaneously, many efforts have been devoted to its synthesis, modification of its composition, study of its electronic structure, optoelectronic properties, and applications. Recently, a record of white light emission with 86 % PLQY was achieved by Luo et al. via simultaneous alloying of Ag⁺ with Na⁺ and Bi³⁺ doping, marking an important milestone in the development of Cs₂AgInCl₆ related materials,” Song said.

“Despite several advantages, major issues with these lead halide perovskites remain their poor stability and toxicity. In order to solve such problems, various attempts have been made to reduce the toxicity of perovskites while still maintaining their efficient optical properties.”

The existence of Bi³⁺ ions decrease the excitation (absorption) energy, provides a new absorption channel and increases the energy transfer rate to Eu³⁺ ions. Through adjusting the Bi³⁺ and Eu³⁺ concentrations, a maximum photoluminescence efficiency (PLQY) of 80.1% is obtained in 6% Eu³⁺ and 0.5% Bi³⁺ co-doped Cs₂AgInCl₆ DPs.

“The energy transfer efficiency can be fitted with the decay rates under different Bi³⁺ doping concentrations. It can be seen that the energy transfer rate improves as a whole with the increase of the doping concentration of Bi³⁺, and the optimum energy transfer rate corresponding to the Bi³⁺ concentration is 0.5%. Next, we conducted PLQY test on the materials. For the undoped Cs₂AgInCl₆ DPs, PLQY is only 0.5%, which dramatically increases to 20.1% after the addition of Bi³⁺. After [being] co-doped with Eu³⁺ and Bi³⁺ ions, PLQY continues to increase, and reaches the maximum of 80.1% when the Eu concentration reaches 6%,” Song said.

“Here, we propose a possible mechanism to describe Eu³⁺ emission in Bi/Eu3+: Cs₂AgInCl₆. Cs₂AgInCl₆ DP is a direct bandgap semiconductor. Bi³⁺ doping provides a new absorption channel for the material, which may be caused by the contribution of the Bi³⁺ orbital in the band edge, breaking the STE-state compatibility ban transition, generating a new light absorption channel at a lower energy, and promoting the PLQY emitted by STE. For the Eu³⁺emission, we think there are two pathways. First, the energy transfer from STE to Eu³⁺ ions is possible as we have observed the Eu³⁺ emission in the Eu³⁺ doped Cs2AgInCl6 DPs. Second, the Eu3+ emission may mainly come from the energy transfer from Bi³⁺ ions to Eu³⁺ ions. The Bi³⁺ ions absorb the excitation light and transfer the energy from ¹P₁, ³P₂, ³P₁, ³P₀ levels of Bi³⁺ ions to ⁵D₃, ⁵D₂, ⁵D₁ and ⁵D₀ levels of Eu³⁺ ions. The characteristic emission of Eu³⁺ ions is then formed through ⁵D₀→⁷F_j(j=0,1,2,3) transitions.”

“Finally, we prepared the white light emitting diodes based on Bi³⁺ and Eu³⁺ codoped Cs₂AgInCl₆ DPs were fabricated with the optimum color rendering index of 89, the optimal luminous efficiency of 88.1 lm/W and a half-lifetime of 1493 h. This strategy of imparting optical functions to metal halide DPs may lead to future applications, such as optical fiber communications, daily lighting, military industry, displays, and other fields,” Song said.

More information: Tianyuan Wang et al, Eu³⁺-Bi³⁺ Codoping Double Perovskites for Single-Component White-Light-Emitting Diodes, Energy Material Advances (2023). DOI: 10.34133/energymatadv.0024

Provided by Beijing Institute of Technology Press Co., Ltd

Chemical engineers at Monash University have developed an industrial process to produce acetic acid that uses the excess carbon dioxide (CO₂) in the atmosphere and has a potential to create negative carbon emissions.

Acetic acid is an important chemical used in several industrial processes and is an ingredient in household vinegar, vinyl paints and some glues. Worldwide industrial demand for acetic acid is estimated to be 6.5 million tons per year.

This world-first research, published in Nature Communications, shows that acetic acid can be made from captured CO₂ using an economical solid catalyst to replace the liquid rhodium or iridium based catalysts currently used.

Liquid catalysts require additional separation and purification processes. Using a solid catalyst made from a production method that doesn’t require further processing also reduces emissions.

Lead researcher Associate Professor Akshat Tanksale said the research could be a widely adopted practice for industry. “CO₂ is over abundant in the atmosphere, and the main cause of global warming and climate change. Even if we stopped all the industrial emissions today, we would continue to see negative impacts of global warming for at least a thousand years as nature slowly balances the excess CO₂,” Prof. Tanksale said.

“There is an urgent need to actively remove CO₂ from the atmosphere and convert it into products that do not release the captured CO₂ back into the atmosphere. Our team is focused on creating a novel industrially relevant method, which can be applied at the large scale required to encourage negative emissions.”

The research team first created a class of material called the metal organic framework (MOF) which is a highly crystalline substance made of repeating units of iron atoms connected with organic bridges.

They then heated the MOF in a controlled environment to break those bridges, allowing iron atoms to come together and form particles of a few nanometers in size.

These iron nanoparticles are embedded in a porous carbon layer, making them highly active while remaining stable in the harsh reaction conditions. This is the first time an iron based catalyst has been reported for making acetic acid.

From an industrial point of view, the new process will be more efficient and cost effective. From an environmental perspective, the research offers an opportunity to significantly improve current manufacturing processes that pollute the environment.

This means a solution to slow down or potentially reverse climate change while providing economic benefits to the industry from the sales of acetic acid products.

The researchers are currently in the process of developing the process for commercialization in collaboration with their industry partners as part of the Australian Research Council (ARC) Research Hub for Carbon Utilization and Recycling.

More information: Waqar Ahmad et al, Aqueous phase conversion of CO2 into acetic acid over thermally transformed MIL-88B catalyst, Nature Communications (2023). DOI: 10.1038/s41467-023-38506-5

Journal information: Nature Communications 

Provided by Monash University 

Most states in the U.S. allow people to use cannabis for medical or recreational purposes. Yet all states want their roadways to be safe. A breathalyzer that can accurately identify people who recently smoked cannabis might help them keep impaired drivers off the road—if such a device existed.

But developing a breathalyzer for cannabis is far more difficult than for alcohol, which people exhale in large amounts when drinking. In contrast, the intoxicating component of cannabis, called THC, is thought to be carried inside aerosol particles that people exhale. The total volume of aerosols can be very small, making it difficult to accurately measure their THC content. Currently, there is no standard method for doing this.

Now, researchers at the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder have conducted a study in which they collected breath samples from people both before and after they smoked high-THC cannabis, aka marijuana, and used laboratory instruments (not a handheld device) to measure the amount of THC in their breath.

The goal of this study, published in the Journal of Breath Research, was to begin developing a protocol that yields reproducible results—a necessary step toward a reliable, validated field-based method.

The samples collected before people smoked were important because THC can persist in the bodies of people who frequently use cannabis for a month or more, long after the effects of the drug have worn off.

“One key question that we cannot yet answer is whether breath measurements can be used to distinguish between a person who uses cannabis regularly but hasn’t done so lately, and someone who consumed an hour ago,” said NIST supervisory chemical engineer and study author Tara Lovestead. “Having a reproducible protocol for breath measurements will help us and other researchers answer that question.”

The breath samples were collected in a mobile lab—a comfortably appointed white van that would park conveniently outside participants’ homes. This mobile pharmacology lab was developed by researchers at University of Colorado Boulder, including Cinnamon Bidwell, an assistant professor of psychology and neuroscience and a co-author of the study.

In addition, all participants purchased and used a consistent kind of high-THC cannabis prepared by a licensed dispensary in Boulder, Colorado. This study design allowed the authors to conduct their research without handling high-THC cannabis or otherwise running afoul of federal laws.

At the appointed time, participants popped into the van, gave their pre-use breath sample and also provided a blood sample. They then went back into their residence, smoked cannabis according to their usual custom and returned immediately to the van to provide a second blood sample. Since THC concentrations in blood spike immediately after consuming the drug, researchers compared the before-and-after blood samples to confirm that the participants had in fact just used it. An hour later, the participants gave their second breath sample.

Participants provided breath samples by blowing into a tube containing an “impaction filter” that captured aerosols from their breath. Later in the lab, the researchers extracted the material caught in the filter and measured the concentration of THC and other cannabis compounds using liquid chromatography with tandem mass spectrometry, a laboratory technique that identifies compounds and measures their amount.

Because this was a protocol development study that involved only 18 participants, the results of the analysis do not carry statistical weight. However, they do highlight the need for further study.

“We expected to see higher THC concentrations in the breath samples collected an hour after people used,” Lovestead said. However, THC levels spanned a similar range across pre-use and post-use samples. “In many cases, we would not have been able to tell whether the person smoked within the last hour based on the concentration of THC in their breath.”

“A lot more research is needed to show that a cannabis breathalyzer can produce useful results,” said NIST materials research engineer and co-author Kavita Jeerage. “A breathalyzer test can have a huge impact on a person’s life, so people should have confidence that the results are accurate.”

More information: Kavita M Jeerage et al, THC in breath aerosols collected with an impaction filter device before and after legal-market product inhalation—a pilot study, Journal of Breath Research (2023). DOI: 10.1088/1752-7163/acd410

Journal information: Journal of Breath Research 

Provided by National Institute of Standards and Technology 

Water oxidation reaction involves a four-electron and four-proton transfer process, which requires an uphill energy transformation and limits the efficiency of the overall photocatalytic water splitting reaction.

Although loading appropriate water oxidation cocatalysts can enhance the performance of water oxidation reactions, the interfacial barrier between the semiconductor and the water oxidation cocatalyst can impede the transfer and utilization of photogenerated charges.

Recently, a research team led by Profs. Li Can and Li Rengui from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) has developed a strategy to controllably assemble a charge-transfer mediator in photocatalysis, which could increase surface charge-transfer efficiency and photocatalytic water oxidation activity. The study was published in Angewandte Chemie International Edition on March 23.

Inspired by natural photosynthesis, the researchers employed partially oxidized graphene (pGO) as a charge-transferring mediator on the hole-accumulating facets of lead chromate (PbCrO₄) photocatalyst. The pGO could be selectively assembled on the hole-accumulating facets of PbCrO₄ by an ultrasonic deposition process, and cobalt-complex Co₄O₄ molecules could be anchored on the pGO as water oxidation cocatalyst.

Based on techniques such as surface photovoltage spectroscopy, they confirmed that introducing the pGO charge transfer mediator between the hole-accumulation facets of PbCrO₄ and Co₄O₄ molecules could effectively suppress charge recombination at the interface, thus prolonging the lifetime of photogenerated charges and enhancing photocatalytic water oxidation performance.

“The strategy of rationally assembling charge transfer mediator provides a feasible way for accelerating charge transfer and charge utilization in semiconductor photocatalysis,” said Prof. Li Rengui.

More information: Wenchao Jiang et al, Graphene Mediates Charge Transfer between Lead Chromate and a Cobalt Cubane Cocatalyst for Photocatalytic Water Oxidation, Angewandte Chemie International Edition (2023). DOI: 10.1002/anie.202302575

Journal information: Angewandte Chemie International Edition 

Provided by Chinese Academy of Sciences 

University of Toronto researchers are investigating exposure to second-hand—and even third-hand—marijuana smoke in homes, including the THC that can collect on floors and surfaces.

The researchers, in Faculty of Applied Science & Engineering, have published a new study that models how THC—the main psychoactive ingredient in cannabis—behaves and transforms once it is released in an indoor environment. The study is published in the journal Environmental Science: Atmospheres.

The model enables researchers to explore mitigation strategies that could reduce involuntary exposure levels.

“We began our research on tetrahydrocannabinol (THC), which is the psychoactive part of cannabis that causes intoxication, because when we looked at second- and third-hand smoke, we started to see how much involuntary exposure happens,” says Amirashkan Askari, a Ph.D. candidate in department of chemical engineering and applied chemistry.

Askari co-authored the study with U of T Engineering Associate Professor Arthur Chan and Frank Wania, a professor in the department of physical and environmental sciences at U of T Scarborough.

Between April 2021 and March 2022, Canadians spent $4 billion on regulated, adult-use cannabis, according to Statistics Canada. Dried cannabis accounted for 71.1 percent of sales, indicating that smoking is the most popular method of consumption.

“Any type of smoking, whether it is tobacco or cannabis, leaves behind a suite of pollutants that can remain in homes,” says Chan. “We now have sufficient chemical knowledge about THC to model its behavior in a typical indoor environment.”

Moreover, involuntary THC exposure can continue long after smoking has ceased. This is due to THC’s large and complex chemical structure, which has a strong tendency to stick to surfaces and create third-hand exposure,” says Askari.

“There are a lot of surfaces indoors—tables, chairs and floors. When you calculate the ratio of surfaces to volume, it is quite elevated compared to the outdoors,” he says. “So, when a pollutant is emitted, it always has the chance to migrate from air to surfaces.

“Involuntary exposure to pollutants starts to become more important when we consider infants and children who reside in homes where this smoking takes place. Children tend to touch surfaces more than adults as they crawl or play; they are also known to frequently put their hands or objects in their mouth.”

Askari used a time-dependent indoor mass-balance model to forecast the level of human exposure to THC. The study also examined the effectiveness of mitigating strategies—from air purifiers to surface cleaners—in reducing second- and third-hand exposure from marijuana smoke.

The model was run for one simulated year under the assumption that THC from single-stream smoke (the lighted end) of a burning cannabis cigarette was emitted into the indoor air for one hour daily.

By modeling the exposure level of an adult and a toddler (who were distinguished by body weight) Askari predicted that residents of all ages who are present during smoking sessions are vulnerable to high levels of involuntary second-hand THC.

The exposure analysis also found that carpet and flooring materials were significant reservoirs of THC that migrated from air to surface. Since younger children are prone to object mouthing—a common part of infant and toddler development—this makes them especially sensitive to THC from third-hand exposure. These results, the study concludes, highlight the importance of preventing children from accessing spaces where cannabis smoking takes place, both during and after smoking.

“When it comes to improving indoor air quality, the best way to degrade air pollutants is to shut down the source,” says Askari. “But if our aim is to suppress it, we found the most effective measures were strategies that target the air particles directly. So, if you have an air purifier unit that filters particulate matter from the air, that will reduce that exposure significantly.”

While the researchers’ initial study used computer simulation, the second phase of this cannabis and indoor air pollution research involves experiments in collaboration with the Centre for Addiction and Mental Health (CAMH).

“We had volunteers come in and either smoke or vape cannabis,” says Askari. “We measured the composition of air in real time—while they were consuming the cannabis—so we could see what happens to the air quality. We also did comparisons between smoking and vaping.”

The results from this second study have not been published, but the team hopes this research will help individuals and policymakers better understand how this source of indoor air pollution impacts the health of communities.

“We hope that people will start paying more attention to indoor air quality, not just during these high-emitting activities, but also long after they are over,” Chan says. “Keeping our homes well-ventilated is very effective at lowering our exposures, even if it is just for a brief period of time during and after smoking.”

More information: Amirashkan Askari et al, Modeling the fate and involuntary exposure to tetrahydrocannabinol emitted from indoor cannabis smoking, Environmental Science: Atmospheres (2023). DOI: 10.1039/D2EA00155A

Provided by University of Toronto 

Insilico Medicine, a clinical stage generative artificial intelligence (AI)-driven drug discovery company, today announced that it combined two rapidly developing technologies, quantum computing and generative AI, to explore lead candidate discovery in drug development and successfully demonstrated the potential advantages of quantum generative adversarial networks in generative chemistry.

The study, published in the Journal of Chemical Information and Modeling, was led by Insilico’s Taiwan and UAE centers which focus on pioneering and constructing breakthrough methods and engines with rapidly developing technologies—including generative AI and quantum computing—to accelerate drug discovery and development.

The research was supported by University of Toronto Acceleration Consortium director Alán Aspuru-Guzik, Ph.D., and scientists from the Hon Hai (Foxconn) Research Institute.

“This international collaboration was a very fun project,” said Alán Aspuru-Guzik, director of the Acceleration Consortium and professor of computer science and chemistry at the University of Toronto. “It sets the stage for further developments in AI as it meets drug discovery. This is a global collaboration where Foxconn, Insilico, Zapata Computing, and University of Toronto are working together.”

Generative Adversarial Networks (GANs) are one of the most successful generative models in drug discovery and design and have shown remarkable results for generating data that mimics a data distribution in different tasks. The classic GAN model consists of a generator and a discriminator. The generator takes random noises as input and tries to imitate the data distribution, and the discriminator tries to distinguish between the fake and real samples. A GAN is trained until the discriminator cannot distinguish the generated data from the real data.

In this paper, researchers explored the quantum advantage in small molecule drug discovery by substituting each part of MolGAN, an implicit GAN for small molecular graphs, with a variational quantum circuit (VQC), step by step, including as the noise generator, generator with the patch method, and quantum discriminator, comparing its performance with the classical counterpart.

The study not only demonstrated that the trained quantum GANs can generate training-set-like molecules by using the VQC as the noise generator, but that the quantum generator outperforms the classical GAN in the drug properties of generated compounds and the goal-directed benchmark.

In addition, the study showed that the quantum discriminator of GAN with only tens of learnable parameters can generate valid molecules and outperforms the classical counterpart with tens of thousands parameters in terms of generated molecule properties and KL-divergence score.

“Quantum computing is recognized as the next technology breakthrough which will make a great impact, and the pharmaceutical industry is believed to be among the first wave of industries benefiting from the advancement,” said Jimmy Yen-Chu Lin, Ph.D., GM of Insilico Medicine Taiwan and corresponding author of the paper. “This paper demonstrates Insilico’s first footprint in quantum computing with AI in molecular generation, underscoring our vision in the field.”

Building on these findings, Insilico scientists plan to integrate the hybrid quantum GAN model into Chemistry42, the Company’s proprietary small molecule generation engine, to further accelerate and improve its AI-driven drug discovery and development process.

Insilico was one of the first to use GANs in de novo molecular design, and published the first paper in this field in 2016. The Company has delivered 11 preclinical candidates by GAN-based generative AI models and its lead program has been validated in Phase I clinical trials.

“I am proud of the positive results our quantum computing team has achieved through their efforts and innovation,” said Alex Zhavoronkov, Ph.D., founder and CEO of Insilico Medicine. “I believe this is the first small step in our journey. We are currently working on a breakthrough experiment with a real quantum computer for chemistry and look forward to sharing Insilico’s best practices with industry and academia.”

More information: Po-Yu Kao et al, Exploring the Advantages of Quantum Generative Adversarial Networks in Generative Chemistry, Journal of Chemical Information and Modeling (2023). DOI: 10.1021/acs.jcim.3c00562

The data acquisition code and source codes associated with this study are publicly available at: github.com/pykao/QuantumMolGAN-PyTorch

Journal information: Journal of Chemical Information and Modeling 

Provided by Insilico Medicine 

To be able to exploit the advantages of elements and their molecular compounds in a targeted manner, chemists have to develop a fundamental understanding of their properties. In the case of the element bismuth, a team from the Max Planck Institut für Kohlenforschung has now taken an important step.

Chemists at the Max Planck Institut für Kohlenforschung strive for the rational design of chemical processes that lead to more efficient and sustainable chemistry for academia as well as industry. A fundamental understanding of the properties of elements such as bismuth and their molecular compounds is necessary in order to be able to take advantage of their potential for catalysis.

A team led by Josep Cornellà and Frank Neese, group leader and director at the Max Planck Institut für Kohlenforschung, has now found that there are still some “white spots” in the chemical landscape that need to be tapped. The researchers have now published their work on an intriguing property of new bismuth complexes in the journal Science.

Why bismuth? Research group leader Josep Cornellà’s team has been interested in this particular metal for quite a while. “Bismuth can offer some advantages—compared to other metals. For example, it is more readily available and less toxic than other elements. In addition, special properties of bismuth that other ‘classical’ catalysis candidates do not have could play a role in future reaction designs,” Cornellà explains.

What is it that makes the Mülheim Bismuth molecule so special? Atoms consist of the atomic nucleus as well as an atomic shell formed by electrons. When molecules are synthesized from atoms or fragments, usually pairs of electrons from different atoms come together to for chemical bonds. However, chemists are often interested in situation that deviate from this situation, which is the case when the molecules have unpaired electrons. Such systems tend to be highly reactive and will readily interact with other molecules.

“Normally, molecules with unpaired electrons are always magnetic,” explains Frank Neese. But now the researchers of the Kohlenforschung have developed a molecule containing bismuth that has unpaired electrons and yet, strangely enough, shows no magnetism at all. The solution to this riddle has to do with, among other things, the special position of bismuth in the periodic table of the elements.

Bismuth is the heaviest of the stable elements—all subsequent elements are radioactive. Due to the particularly heavy atomic nucleus, the electrons show a special behavior, which can only be understood with the help of Einstein’s theory of relativity. These properties lead to the initially perplexing experimental finding.

“Our molecule is not really ‘non-magnetic’,” the researchers explain, “but there is no magnetic field on Earth strong enough to detect magnetism in our system.” The fact that the researchers were able to calculate the fascinating properties of this molecule from first principles of physics is due to the quantum chemistry program package ORCA, developed in Mülheim and widely used throughout all chemical disciplines by tens of thousands of chemists worldwide.

With their work, the scientists from Mülheim have added an important point to the “chemical profile” of bismuth. This may be of importance in the future when designing new types of catalysts.

More information: Yue Pang et al, Synthesis and isolation of a triplet bismuthinidene with a quenched magnetic response, Science (2023). DOI: 10.1126/science.adg2833

Journal information: Science 

Provided by Max Planck Society 

A research team, led by Professor Dong Woog Lee from the Department of Chemistry at UNIST, in collaboration with Professor Byeong-Su Kim from the Department of Chemistry at Yonsei University, has discovered that the synergistic anion–π interactions serve as a key principle in enhancing the cohesion of synthetic polymers.

In this study, the researchers developed an epoxy monomer-based polymer that mimics the structural features of mussel foot proteins and experimentally demonstrated that anion–π interactions are pivotal in strengthening polymer cohesion.

The paper is published in the journal Proceedings of the National Academy of Sciences.

Anion–π interactions are non-covalent bonds formed between negatively charged molecules (anions) and the π electron systems of aromatic rings. While these interactions are known to play critical roles in biological processes such as enzyme catalysis and ion transport, research exploring their application in synthetic polymers remains scarce.

Inspired by mussels, which exhibit remarkable adhesive properties in natural environments, the research team focused on the plantar proteins of these organisms. Through an analysis of the key components contributing to their strong binding capabilities, the scientists found that the structural characteristics of 3,4-dihydroxyphenylalanine (DOPA) and aspartic acid are particularly significant.

To advance their findings, the research team designed functional monomers that replicate these structural features, leading to the synthesis of a novel polymer. This work proposes a new design methodology for polymers, taking into account the complex intermolecular interactions present in biological systems.

Specifically, the monomer that emulates the DOPA structure provides the π-electronic field of the aromatic ring, while the monomer representing aspartic acid introduces the anion necessary for anion–π interactions within the polymer framework. Furthermore, the team employed a surface force apparatus (SFA) to quantitatively analyze the cohesiveness of the polymer under various conditions.

The team compared the cohesion of the polymer in neutral environments, where its functional groups are ionized, against acidic conditions, where they remain non-ionized.

Their findings revealed that in neutral environments, anion–π interactions serve as the principal binding force, significantly enhancing polymer cohesion. In contrast, under acidic conditions, hydrogen bonding dominates, resulting in comparatively weaker cohesion.

This study marks the first experimental evidence highlighting the decisive role of anion–π interactions in reinforcing cohesion among synthetic polymers.

The implications of these findings open avenues for innovative polymer design strategies applicable in diverse fields, including adhesives, self-assembly systems, catalysts, and drug delivery.

More information: Seunghyun Lee et al, Synergistic anion–π interactions in peptidomimetic polyethers, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2419404122

Journal information: Proceedings of the National Academy of Sciences 

Provided by Ulsan National Institute of Science and Technology

A small team of materials scientists and chemical engineers at Qingdao University, in China, has developed a self-powered, three-component biosensor that can kill bacteria in water samples. The study is published in the journal Advanced Functional Materials.

As the world’s population continues to rise, scientists are looking for ways to sustain so many people. One area of concern is safe drinking water, particularly in regions that do not have sophisticated water treatment facilities. In this new effort, the team in China developed a biosensor that could, in theory, be used in developing countries to make water safe for drinking.

Biosensors are made using living organisms or tissues. Prior research has shown that they can be faster and less expensive than those based on traditional technology, especially in applications such as testing water for the presence of bacteria. Unfortunately, they tend to also suffer from degradation.

The researchers overcame this problem by creating their biosensor with three components. The first was an enzyme-based fuel cell to power the cell. The enzymes generate electricity via chemical reactions that occur once the sensor is placed in a water sample. To prevent their power generator from losing stability, the team put it in a hollow metal-organic framework.

The second component used a type of antibody known as an aptamer—their DNA strands were chosen specifically to bind with the exterior of an E. coli bacterium.

The third component was the part that kills the bacteria. It is accomplished by the oxidation of the silver nanoparticles used by the second component. The oxidation produces hydrogen peroxide, which kills the bacterium.

In testing, the sensor was capable of detecting E. coli at very low concentrations. It was also efficient, killing 99.9% of bacteria in a given sample over just a few hours. The biosensor also distinguished between different kinds of bacteria, suggesting it could be modified to kill other microbes as well. When tested on seawater samples, the sensor had recovery rates of 91.06% to 101.9% and remained workable after five user cycles.

More information: Yanfang Wang et al, Self‐Powered Biosensor‐Based Multifunctional Platform for Detection and In Situ Elimination of Bacteria, Advanced Functional Materials (2025). DOI: 10.1002/adfm.202420480

Journal information: Advanced Functional Materials