The scientific community has witnessed a groundbreaking development in sustainable chemistry with the creation of a shape-shifting single-atom catalyst at the Politecnico di Milano. This innovative material has demonstrated the capability to selectively adapt its chemical activity, paving the way for more efficient and programmable industrial processes.

Published in the Journal of the American Chemical Society, one of the world’s most esteemed scientific journals in chemistry, this study marks a significant breakthrough in the field of single-atom catalysts. For the first time, scientists have successfully designed a material that can change its catalytic function depending on the chemical environment, much like a ‘molecular switch.’ This allows complex reactions to be performed more cleanly and efficiently, using less energy than conventional processes.

The research focuses on a palladium-based catalyst in atomic form encapsulated in a specially designed organic structure. This unique setup enables the material to ‘switch’ between two essential reactions in organic chemistry – bioreaction and carbon-carbon coupling – simply by varying the reaction conditions. The team has successfully demonstrated this phenomenon, showcasing the potential for more intelligent, selective, and sustainable chemical transformations.

Lead researcher Gianvito Vilé, lecturer at the Politecnico di Milano’s ‘Giulio Natta’ Department of Chemistry, Materials and Chemical Engineering, emphasizes the significance of their discovery: “We have created a system that can modulate catalytic reactivity in a controlled manner, paving the way for more intelligent, selective, and sustainable chemical transformations.”

The new catalyst stands out not only for its reaction flexibility but also for its stability, recyclability, and reduced environmental impact. ‘Green’ analyses conducted by the team reveal a substantial decrease in waste and hazardous reagents, making it an exemplary model for sustainable chemistry.

This study is the result of an international collaboration with esteemed institutions from around the world, including the University of Milan-Bicocca, the University of Ostrava (Czech Republic), the University of Graz (Austria), and Kunsan National University (South Korea). The joint efforts of these researchers have led to a groundbreaking achievement that has far-reaching implications for the field of green chemistry.

The discovery of a new type of molecular carbon allotrope, known as cyclocarbon, has been a long-standing challenge for chemists. A team of researchers from Oxford University’s Department of Chemistry, led by Dr Yueze Gao and senior author Professor Harry Andersen, have successfully synthesized a stable 48-atom carbon ring in solution at room temperature. This achievement marks a significant breakthrough in the field, as previous attempts to study cyclocarbons were limited to the gas phase or extremely low temperatures (4 to 10 K).

The researchers employed a unique approach by synthesizing a cyclocarbon catenane, where the C48 ring is threaded through three other macrocycles. This design increases the stability of the molecule, preventing access to the sensitive cyclocarbon core. The team developed mild reaction conditions for the unmasking step in the synthesis process, which allowed them to achieve a stable cyclocarbon in solution at 20°C.

The cyclocarbon catenane was characterized using various spectroscopic techniques, including mass spectrometry, NMR, UV-visible, and Raman spectroscopy. The observation of a single intense 13C NMR resonance for all 48 sp1 carbon atoms provides strong evidence for the cyclocarbon catenane structure.

Lead author Dr Yueze Gao stated that achieving stable cyclocarbons in a vial at ambient conditions is a fundamental step, making it easier to study their reactivity and properties under normal laboratory conditions. Senior author Professor Harry Andersen added that this achievement marks the culmination of a long endeavor, with the original grant proposal written in 2016 based on preliminary results from 2012-2015.

The study also involved researchers from the University of Manchester, the University of Bristol, and the Central Laser Facility, Rutherford Appleton Laboratory. This collaborative effort demonstrates the power of interdisciplinary research in advancing our understanding of complex molecular systems.

This achievement has significant implications for future studies on cyclocarbons and their potential applications in various fields. The researchers’ innovative approach to synthesizing stable cyclocarbons at room temperature opens up new possibilities for exploring the properties and reactivity of these intriguing molecules.

As scientists continue to push the boundaries of what is possible, they stumble upon unexpected discoveries that challenge our understanding of the world. A recent breakthrough at the SLAC National Accelerator Laboratory has revealed the secret chemistry of gold, a metal once thought to be unreactive and boring. Researchers have successfully formed solid binary gold hydride, a compound made exclusively of gold and hydrogen atoms, under extreme conditions.

The team led by Mungo Frost, staff scientist at SLAC, was studying how hydrocarbons form diamonds under high pressure and heat. In their experiments at the European XFEL in Germany, they embedded gold foil into the samples to absorb X-rays and heat the weakly absorbing hydrocarbons. To their surprise, they not only observed the formation of diamonds but also discovered the formation of gold hydride.

“It was unexpected because gold is typically chemically very boring and unreactive — that’s why we use it as an X-ray absorber in these experiments,” said Mungo Frost. “These results suggest there’s potentially a lot of new chemistry to be discovered at extreme conditions where the effects of temperature and pressure start competing with conventional chemistry, and you can form these exotic compounds.”

The research team used a diamond anvil cell to squeeze hydrocarbon samples to pressures greater than those within Earth’s mantle and then heated them to over 3,500 degrees Fahrenheit using X-ray pulses from the European XFEL. This allowed them to resolve the structural transformations within the samples and observe how the gold lattice scattered X-rays.

The team found that under these extreme conditions, hydrogen was in a dense, superionic state, flowing freely through the gold’s rigid atomic lattice and increasing its conductivity. This phenomenon is not directly accessible through other experimental means, but studying it could provide new insights into nuclear fusion processes inside stars like our sun and help develop technology to harness fusion energy on Earth.

The discovery of gold hydride also opens up new avenues for exploring chemistry at extreme conditions. Gold, once thought to be unreactive, was found to form a stable compound with hydrogen under high pressure and temperature. This suggests that more research is needed to understand the properties of materials under these extreme conditions.

In addition to their findings on gold hydride, the team also developed simulation tools that could model other exotic material properties in extreme conditions. These tools have the potential to be applied beyond this specific study, offering new opportunities for researchers to explore and understand complex phenomena.

The research was conducted by an international team of scientists from SLAC National Accelerator Laboratory, European XFEL, DESY, Rostock University, Frankfurt University, Bayreuth University, Carnegie Institution for Science, Stanford University, and the Stanford Institute for Materials and Energy Sciences (SIMES). The work was supported by the DOE Office of Science.