Advisory board member Lucia Maini and her mechanochemistry students at the University of Bologna have selected their favourite articles from RSC Mechanochemistry. The students’ perspectives on the articles and the field of mechanochemistry will be presented in a series of six blog posts. The third group of students will discuss:
This article describes a solvent-free mechanochemical strategy for performing a Sonogashira cross-coupling, a reaction that is traditionally carried out in solution and widely employed for the formation of C(sp²)–C(sp) bonds. The study focuses on substituting pre-assembled palladium–ligand complexes, whose synthesis requires additional steps, controlled atmospheres, and high cost, with catalytic species generated directly from bulk metals under ball-milling conditions. Because the Sonogashira reaction relies on both palladium and copper, the authors explore if the copper vial itself, when exposed to palladium powder and ligands during milling, can become the catalyst through palladium embedding.
In the experimental setup, the aryl halide and terminal alkyne were milled in a copper vial together with palladium powder and triphenylphosphine, which served to form the active Pd complex in situ. The milling apparatus was equipped with a thermocouple, allowing precise control of the reaction temperature, that is essential for reproducibility under mechanochemical conditions. After several reaction cycles, the authors observed that the coupling proceeded even without adding fresh palladium powder. To assess this evidence, they performed the same reaction in a newly machined copper vial; in this case only unreacted starting materials were recovered, confirming that catalytic activity depended on palladium that had become embedded into the original vial surface.
With this phenomenon established, the authors conducted substrate screening using a variety of terminal alkynes and aryl halides. Good to excellent yields were obtained for many coupling partners, highlighting the versatility of the mechanochemical protocol. Finally, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses were performed to investigate the modified vial surface. This revealed that palladium was incorporated into the copper, but in discrete and localized regions rather than as a uniform coating. This observation sheds light on catalyst evolution during mechanochemical processing.
Overall, the study demonstrates that catalytic activity can emerge directly from metal surfaces under milling conditions, offering a sustainable and simplified alternative to conventional solution-phase catalysis.
What drew you to study Mechanochemistry initially, and what areas have you found most interesting?
We wanted to study mechanochemistry because it is a fresh and new approach to synthetic strategies that were considered unimprovable. Since now the challenge is not only the efficiency, but also the sustainability; research on mechanochemical approaches has become crucial and something we should be able to dig into.
Why did you choose this article, did you find anything surprising?
We have chosen this article because of our interest in organic chemistry, and our enthusiasm for mechanochemistry, as outlined above. This paper represents an unusual approach to a common reaction that is important in industry (for example in the field of semiconductors) and it is surprising because we are used to considering the Sonogashira reaction only in solution.
Why is this article important, what gap in the literature does this research aim to fill?
This article is important because it takes up the challenge of decreasing the environmental impact of a common organic chemistry reaction, decreasing the amount of catalyst and trying to avoid the use of solvents. It opens up the possibility of also applying this approach to other reactions that require more than one catalyst, so also the scaling up aspect would be favourable.
Consider the real-world applications or implications of this article, what are the strengths and/or limitations of this article that may need to be explored further?
The scaling up is surely a challenge, and the usage of this technique on an industrial scale should be investigated to see if it can be profitable on a higher scale. Also, the protocol and the approach should be optimized for other substrates, since it has been shown that the reaction did not always achieve good yields. Another thing that can be done is to investigate a way to make the coating of the palladium more uniform, avoiding the separation between embedding areas that probably leads to a lowering of the overall yield.
Thomas Jia Hao Hu, Jacopo Suozzi, Marta Innocenzi and Giacomo Marchignoni
Thomas, Jacopo, Marta and Giacomo are students in the Master’s program in Photochemistry and Molecular Materials. They share a passion for chemistry in all of its different nuances, putting together different branches: computational chemistry, photochemistry and unfortunately even organic chemistry. Jacopo aims to contribute in making chemistry greener and to help other people while doing this. Giacomo, on the other hand, would like to contribute to the world of medicine through chemistry, potentially by developing new drugs and biosensors. Thomas is hoping to develop methodologies and catalytic processes while chasing his passion for chemistry. Marta aims to research the depth of photochemistry to achieve more sustainable and cheaper ways of living, keeping in mind the unicity of each territory.
Check out the article, published in RSC Mechanochemistry:
Sheeniza Shah, Mennatullah M. Mokhtar, Thinh Tran, Kathleen Floyd, Lizette Mella, Tim Dao, Alexandria Garza, James Batteas and James Mack
RSC Mechanochem., 2026, 3, 46-55
Discover all of the selected articles in the RSC Mechanochemistry Students’ Choice collection.
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Are you ready to contribute to the future of mechanochemistry? RSC Mechanochemistry offers you an inclusive and dedicated home for the ideas, scientific language and approaches that cut across the many disciplines mechanochemistry touches. Here we are seeking to build knowledge, as well as foster innovation and discovery at this forefront of chemistry. Whether you are seeking to understand the fundamentals of mechanochemistry, or you are excited by its applications and potential, this journal is for you. All of the content in this journal is gold open access, which means that you can read every article for free, and we are covering all publication costs until mid-2026. |