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Chemists solve century-old mechanistic puzzle of copper catalyst

The Ullmann reaction is one of the oldest reactions in organometallic chemistry. It is one of the most widely used copper-mediated coupling reactions, widely applied in the construction of carbon-carbon and carbon-heteroatom bonds due to its excellent substrate generality.

There has been considerable controversy regarding the redox mechanism of copper in this reaction for a long time. The widely accepted mechanistic hypothesis involves a Cu(I/III) cycle. However, copper(III) species are extremely difficult to observe in real reaction systems, and whether other interactions exist between copper species remains unknown.

In a study published in Nature on September 22, Shen Qilong’s lab from the Shanghai Institute of Organic Chemistry of the Chinese Academy of Sciences, along with Professor K. N. Houk from the University of California, Los Angeles, provided solid evidence that the Ullmann-type reaction might proceed via a Cu(I)/Cu(III)/Cu(II)/Cu(III)/Cu(I) catalytic cycle.

Energy-efficient catalyst converts water pollutants into useful ammonia

When the current method for producing something is estimated to consume a staggering 1–2% of the annual global energy supply, it means we need to make a change. The Haber-Bosch process produces ample amounts of ammonia (NH3)—a valuable chemical compound that has a wide array of uses in fields such as agriculture, technology, and pharmaceuticals—while consuming a lot of energy.

A research team at Tohoku University has made a significant contribution to an alternate method for converting harmful nitrate pollutants in water into ammonia, addressing both environmental and energy challenges.

Their findings are published in Advanced Functional Materials.

How diamond fails under extreme electrical fields

A research team from the University of Chinese Academy of Sciences has revealed the failure mechanism of diamond under extreme electrical fields through in situ experiments and molecular dynamics simulations. The study, published in Cell Reports Physical Science, provides critical insights for the design of robust diamond devices.

Diamond is known for its exceptional physical properties, including ultra-high breakdown field strength and , making it a promising material for and high-power electronics. However, its failure process under extreme electrical fields has remained poorly understood before now.

Led by Profs. Yan Qingbo and Chen Guangchao, the researchers used an in situ transmission electron microscopy (TEM) method to observe the breakdown process in real time. They found that diamond failure begins preferentially along the (111) crystal plane due to stress-induced lattice distortion and subsequent amorphization, rather than transforming into graphite.

Hubble Reveals White Dwarf Devouring a Frozen, Pluto-Like World

Astronomers using the Hubble Space Telescope have uncovered the remains of a frozen, Pluto-like world being devoured by a distant white dwarf star.

This cosmic “crime scene” not only reveals the dramatic fate of planetary fragments but also strengthens the case that the ingredients for life are scattered throughout the galaxy.

Discovery of a frozen, water-rich planetary fragment.

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