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Chemistry

Illuminating the Twist: Light-Controlled Supramolecular Chirality

In a striking demonstration of molecular control, a team of scientists has harnessed light to reverse the twist in self-assembling molecules. The study identifies how trace residual aggregates in photo-responsive azobenzene solutions can reverse helical chirality through secondary nucleation. By using precise control of ultraviolet and visible light, the researchers could switch between the rotation of helices, offering a breakthrough for novel materials with tunable properties.

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The self-assembly of molecules into complex structures is a crucial phenomenon in material science. Researchers from Japan have made a significant breakthrough by elucidating a technique where a small amount of residual aggregates drastically alters the self-assembly process of photo-responsive molecules. This study, led by Professor Shiki Yagai and his team, was published online in Nature Nanotechnology on April 11, 2025.

In recent years, there has been an increasing focus on controlling the size and hierarchical structures of self-assembled aggregates to achieve materials with desired properties. However, self-assembly is a dynamic process that requires precise control. As Professor Yagai explains, “During the process of self-assembly, molecules repeatedly associate and dissociate,” making it challenging to predict the final structure of the formed aggregates.

The research team focused on the self-assembly of a chiral, photoresponsive azobenzene molecule that naturally forms left-handed helical aggregates. They discovered that the presence of a small amount of residual aggregates within the solution induces a drastic change in the assembly process and leads to the formation of right-handed helical aggregates instead.

The team found that when the scissor-shaped azobenzene molecule is dissolved in an organic solvent at room temperature, it forms a closed scissor-like folded structure that further extends into a helical assembly. This is due to the chirality of the molecule, which causes it to fold like left-handed scissors and twist to form a left-handed helical stacking of the assembly.

The molecules are photoresponsive, meaning they can change their structure in response to light. When exposed to weak ultraviolet (UV) light, the helical assembly disassembles back into individual molecules, and upon subsequent exposure to visible light, the molecules reassemble into helical structures again.

Interestingly, under certain conditions, the resulting helical aggregates were found to be right-handed instead of left-handed, and exposure to stronger UV light followed by visible light led to the regeneration of the original left-handed helical aggregates. The team attributed this phenomenon to “secondary nucleation,” which explains why meta-stable right-handed aggregates are preferably formed instead of left-handed aggregates.

The researchers also discovered that the intensity of visible light affects the timing of the assembly, with strong visible light promoting rapid assembly while minimizing the influence of residual aggregates. By optimizing the intensities of UV and visible light, the team successfully controlled the switching between left- and right-handed helical structures which were dependent on the influence of residual aggregates.

Furthermore, it was found that the stable left-handed aggregates and meta-stable right-handed aggregates also exhibit opposite electron spin polarization, signifying the tuning of electronic characteristics of the helices. This study aims to explore the critical role of residual aggregates and explained how light-enabled fine-tuning can result in the fabrication of novel functional materials, giving promising insights into the field of material science.

Chemistry

Revolutionizing Magnetic Field Technology: A Breakthrough Design for MRI and Magnetic Levitation

Two German physicists have reimagined how to create powerful and uniform magnetic fields using compact permanent magnets. By overcoming the limitations of the well-known Halbach array, which works only with infinitely long magnets, they engineered innovative 3D magnet arrangements that work in practical, finite-size setups. Their designs not only boost field strength but also enhance homogeneity, verified through real-world experiments. This game-changing advancement could help bring affordable MRI technology to underserved regions and power applications like particle accelerators and magnetic levitation systems.

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Physicists at the University of Bayreuth and Johannes Gutenberg University Mainz have made a groundbreaking discovery that could transform the way we generate magnetic fields. Prof. Dr. Ingo Rehberg and Dr. Peter Blümler developed an innovative approach to create homogeneous magnetic fields using compact, permanent magnets. This breakthrough design outperforms the traditional Halbach arrangement, which is ideal only for infinitely long and therefore unrealizable magnets.

The new approach presents optimal three-dimensional arrangements of very compact magnets, idealized by point dipoles. The researchers investigated the optimal orientation of the magnets for two geometries relevant to practical use: a single ring and a stacked double ring. This “focused” design allows the generation of homogeneous fields outside the magnet plane, enabling applications such as magnetic levitation systems.

To validate their theoretical predictions, Rehberg and Blümler constructed magnet arrays from 16 FeNdB cuboids mounted on 3D-printed supports. The resulting magnetic fields were measured and compared with theoretical calculations, revealing excellent agreement. In terms of both magnetic field strength and homogeneity, the new configurations clearly outperform the classical Halbach arrangement.

The potential applications of this breakthrough design are vast. Conventional MRI technology relies on powerful superconducting magnets, which are technically complex and extremely costly. The new approach offers a promising alternative for generating homogeneous magnetic fields using permanent magnets. Additionally, this innovation could lead to advancements in particle accelerators and magnetic levitation systems.

This study was published in the renowned interdisciplinary journal Physical Review Applied, showcasing significant advances at the intersection of physics with engineering, materials science, chemistry, biology, and medicine. The implications of this breakthrough design are far-reaching, and further research is expected to uncover new possibilities for its applications.

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Chemistry

Breakthrough at Rice University Keeps CO2 Electrolyzers Running 50x Longer with a Surprisingly Simple Method

A Rice University team discovered that bubbling CO₂ through a mild acid dramatically improves the lifespan and efficiency of electrochemical devices that convert CO₂ into useful fuels. This simple trick prevents salt buildup—a major barrier to commercialization—by altering local chemistry just enough to keep salts dissolved and flowing. The result? A device that ran for over 4,500 hours without clogging, using common catalysts and scalable technology. It’s a breakthrough that could make green CO₂ conversion far more viable in the real world.

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The researchers at Rice University have made a groundbreaking discovery that vastly improves the stability of electrochemical devices converting carbon dioxide into useful fuels and chemicals. Their innovative approach involves simply sending the CO2 through an acid bubbler, which dramatically extends the operational life of these devices by more than 50 times.

Electrochemical CO2 reduction (CO2RR) is a promising green technology that uses electricity to transform climate-warming CO2 into valuable products like carbon monoxide, ethylene, or alcohols. These products can be further refined into fuels or used in industrial processes, potentially turning a major pollutant into a feedstock.

However, the practical implementation of this technology has been hindered by poor system stability due to salt buildup in gas flow channels. This issue occurs when potassium ions migrate from the anolyte across the anion exchange membrane to the cathode reaction zone and combine with CO2 under high pH conditions.

To combat this problem, the Rice team tried a clever twist on standard procedures. Instead of using water to humidify the CO2 gas input into the reactor, they bubbled the gas through an acid solution such as hydrochloric, formic, or acetic acid.

The vapor from the acid altered local chemistry in trace amounts, preventing salt crystallization and channel blockage. The effect was remarkable: systems operated stably for over 4,500 hours in a scaled-up electrolyzer, compared to just about 80 hours under standard water-humidified CO2 conditions.

This breakthrough has significant implications for the development of carbon capture and utilization technologies. By extending the lifespan of CO2 electrolyzers, this innovation can help make these technologies more commercially viable and sustainable.

The simplicity of this approach is noteworthy, as it requires only small tweaks to existing humidification setups, which means it can be adopted without significant redesigns or added costs. This makes it an attractive solution for industries looking to integrate carbon utilization technologies into their operations.

This work was supported by the Robert A. Welch Foundation, Rice University, the National Science Foundation, and the David and Lucile Packard Foundation. The researchers’ findings have the potential to transform the field of CO2RR and pave the way for more durable, scalable electrochemical devices that can efficiently convert CO2 into valuable products.

The study’s authors highlight the significance of this discovery, saying it “addresses a long-standing obstacle with a low-cost, easily implementable solution.” They also emphasize its potential impact on making carbon utilization technologies more commercially viable and sustainable.

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Chemistry

“Rewriting Chemistry with Light: A Breakthrough in Fossil Fuel Transformation”

Researchers at Colorado State University have developed a new photoredox catalysis system that uses visible light mimicking photosynthesis to drive energy-intensive chemical reactions at room temperature. This groundbreaking process could significantly reduce the energy required in chemical manufacturing, especially in industries reliant on fossil fuels.

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The world is on the cusp of a revolutionary change in the way we transform fossil fuels into useful modern chemicals. Researchers at Colorado State University have made a groundbreaking discovery that uses light to rewrite the chemistry of fossil fuels, reducing energy demands and associated pollution. This breakthrough, published in Science, could be a game-changer for industries reliant on chemical manufacturing.

At the forefront of this research are professors Garret Miyake and Robert Paton from the Department of Chemistry and the Center for Sustainable Photoredox Catalysis (SuPRCat). Inspired by photosynthesis, their organic photoredox catalysis system harnesses visible light to gently alter the properties of chemical compounds. By exposing them to two separate photons, the team’s system generates energy needed for desired reactions, performing super-reducing reactions that are normally difficult and energy-intensive.

The research has shown remarkable results on aromatic hydrocarbons – resistant compounds like benzene in fossil fuels. Miyake boasts that their technology is “the most efficient system currently available” for reducing these compounds, paving the way for the production of chemicals needed for plastics and medicine.

This work continues the efforts of the U.S. National Science Foundation Center for Sustainable Photoredox Catalysis at CSU, led by Miyake as its director. This multi-institution research effort aims to transform chemical synthesis processes across various uses, making synthetic and computational chemists team up to understand the fundamental chemical nature of photoredox catalysis.

Katharine Covert, program director for the NSF Centers for Chemical Innovation program, highlights the importance of photoredox catalysis in pharmaceutical development and other industries. Through the NSF Center for Sustainable Photoredox Catalysis, researchers are developing catalysis systems similar to the one described in this paper to support energy-efficient production of ammonia for fertilizers, the breakdown of PFAS forever chemicals, and the upcycling of plastics.

Miyake emphasizes the urgency of meeting these challenges and making a more sustainable future for our world. He concludes that “the world has a timeclock that is expiring,” and we must develop sustainable technologies before it’s too late.

This breakthrough has far-reaching implications, not just in chemical manufacturing but also in addressing pressing environmental concerns. As researchers continue to push the boundaries of what’s possible with light-based chemistry, one thing is certain – the future of fossil fuel transformation has never looked brighter.

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