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Free radicals caught in the act with slow spectroscopy

Why does plastic turn brittle and paint fade when exposed to the sun for long periods? Scientists have long known that such organic photodegradation occurs due to the sun's energy generating free radicals: molecules that have lost an electron to sunlight-induced ionization and have been left with an unpaired one, making them very eager to react with other molecules in the environment. However, the exact mechanisms for how and why the energy from the sun's photons get stored and released in the materials over very long periods have eluded empirical evidence. The problem lies in the timeframe. While scientists have access to extremely sophisticated spectroscopy equipment capable of measuring the energy levels of individual electrons at femtosecond to millisecond scales in organic materials, they have paid little attention to time scales beyond seconds—and these are processes that can take years.

‘Self-healing’ polymer brings perovskite solar tech closer to market

This perovskite solar module is better able to contain the lead within its structure when a layer of epoxy resin is added to its surface. This approach to tackling a long-standing environmental concern helps bring the technology closer to commercialization. Credit: OIST

A protective layer of epoxy resin helps prevent the leakage of pollutants from perovskite solar cells (PSCs), according to…

A new organometallic compound challenges a fundamental principle of textbook chemistry

For more than a century, the well-known 18-electron rule has guided the field of organometallic chemistry. Now, researchers at Okinawa Institute of Science and Technology (OIST), in collaboration with scientists from Germany, Russia, and Japan, have successfully synthesized a novel organometallic compound that challenges this longstanding principle. They have created a stable 20-electron derivative of ferrocene, an iron-based metal-organic complex, which could lead to exciting possibilities in chemical science. "For many transition metal complexes, they are most stable when surrounded by 18 formal valence electrons. This is a chemical rule of thumb on which many key discoveries in catalysis and materials science are based," said Dr. Satoshi Takebayashi, lead author of the paper published in Nature Communications.

Tailored single atom platforms hold promise for next-generation catalysis

Catalysts play a vital role in modern society, supporting processes from metallurgy to pharmaceutical production. To reduce environmental impact and maximize efficiency, science has pushed the boundaries between homogeneous and heterogeneous catalysis toward single-atom catalysts. However, working with individual atoms poses enormous challenges: it is difficult to overcome their tendency to aggregate into clusters, especially at temperatures above cryogenic levels, and it is complex to arrange them precisely in specific chemical environments. An international team of researchers from Istituto di Struttura della Materia, National Research Council (CNR-ISM, Italy), the Okinawa Institute of Science and Technology (OIST, Japan), Empa (Switzerland), and University of Rome Tor Vergata (Italy) has developed an innovative approach to overcome these limitations. Through on-surface synthesis (OSS) enabled by atomic-resolution scanning probe microscopy techniques, the scientists fabricated one-dimensional organic polymers capable of selectively binding metal atoms at well-defined coordination sites.

Hidden catalysis: Abrasion transforms common chemistry equipment into reagents

The chemical industry is one of the largest on Earth, essential for supplying us with pharmaceuticals, agrochemicals, materials and more. Great care is taken to optimize reagents and conditions for each reaction, striving for efficiency and, increasingly, sustainability. A growing field of synthesis is mechanochemistry, in which reagents are mixed using mechanical force, making for greener reactions with less solvent usage and enabling access to a wide array of essential chemicals. In a typical mechanochemistry setup, the reagents are placed in a jar filled with balls, which are shaken at high frequency to enable mixing and grinding. Often, solid, insoluble additives such as metal oxides or piezoelectric materials (materials which become electrically polarized under mechanical stress) are included in the reaction mixture, as mechanochemists have commonly believed these additives help activate catalysts or reagents.

Crystal-free mechanoluminescence illuminates new possibilities for next-generation materials

In the 17th century, Francis Bacon described a simple experiment—scraping and fracturing hard sugar in the dark to see sparks of light. This phenomenon is called mechanoluminescence (ML) or triboluminescence (TL), the process of materials emitting light under mechanical stimulation, like grinding or crushing. Usually, ML properties of luminescent compounds are observed in rigid crystalline systems, which limits their real-world applications. Now, researchers at the Okinawa Institute of Science and Technology (OIST) have found a way to generate ML in non-crystalline materials, bringing a new wave of potential applications in engineering, industrial safety and beyond. "Mechanical stimulation of crystals causes fractures. As the crystals are damaged and break down in size, they also start to lose their ML properties, which vastly restricts their application. In crystals, ML is highly dependent on structure and packing, adding complex design requirements. That's why we were interested in amorphous ML materials with longer-lasting luminescence," explains Professor Julia Khusnutdinova, head of the Coordination Chemistry and Catalysis Unit at OIST.