Radical reactions for reversible click chemistry

Click reactions—the subject of the 2022 Nobel Prize in Chemistry —come in many forms, but they all share a few key features . Namely, click chemistry forges new chemical bonds quickly, selectively, and irreversibly. That last feature has now become a bit more optional. A team at Tsinghua University led by Jiang-Fei Xu and Xi Zhang have published a paper detailing their radical new approach to click chemistry: a bond formation between phenothiazine dyes and amines that can be undone using ultraviolet light ( Science 2024, DOI: 10.1126/science.adn2259 ). “The more I read this paper, the more I liked it,” says Craig Hawker , a chemist at the University of California, Santa Barbara, who was not involved in the work. He says it’s interesting, useful chemistry with a lot of potential for researchers to continue building upon. In an email, Xu says the paper started with a serendipitous discovery made