This machine is designed to wind

Think of it as a strategy to make molecular chain mail: a new molecular machine that winds two molecular threads together to make mechanically interlocked molecules often called catenanes. Catenanes characteristic macrocyclic loops held collectively like hyperlinks in a series. To break the chain requires breaking a covalent bond. Although chemists have been making catenanes for many years—their discovery garnered the 2016 Nobel Prize in Chemistry—they often use advanced templating methods. This molecular machine as a substitute twists two molecular threads collectively utilizing mild and warmth (Science 2025, DOI: 10.1126/science.adx5363).

The molecular machine was designed by chemists in Michael Kathan’s lab at Humboldt University of Berlin. Kathan says the concept of constructing such a machine got here to him when he was a graduate pupil finding out switchable molecules. “The question was, What can we do with molecular machines that you cannot do otherwise?” he says.

The core of the catenane-making machine is a molecular motor that makes a unidirectional 180° flip when uncovered, alternatingly, to mild and warmth. Each half-circle flip creates a crossing between the molecular threads. Two crossings entwine the molecule in order that it may possibly kind a catenane, and as soon as the motor has made a full circle, the chemists covalently hyperlink the threads collectively after which chemically snip a hyperlink to the motor, releasing the catenane.

The motor’s synthesis isn’t talked about within the paper and as a substitute takes up 25 pages of the supplemental info printed alongside. Kathan says it was a frightening process. “My coworkers spent most of their time synthesizing these machines,” he says. “It’s always a bummer if the thing you just scribbled on a piece of paper doesn’t work out, and then you invest weeks or months in synthesis and try to figure out how you could make it work experimentally.”

Kathan says his workforce’s method to creating mechanically interlocked molecules isn’t restricted to catenanes however is also used to create molecular knots and rotaxanes. “The method of making these molecules is always the same: You introduce a certain number of crossings in a molecular strand, and then you try to covalently capture them in an appropriate manner,” he says. The molecular machine developed in his lab can introduce an outlined variety of crossing factors in any molecular strand; the strand simply must be sufficiently lengthy and versatile.

David A. Leigh, who makes mechanically interlocked molecules on the University of Manchester, agrees that making completely different torus knots and hyperlinks with this machine could possibly be doable if you will get the motor to make a couple of full flip—one thing Kathan’s lab was in a position to do, though they had been unable to make the mandatory covalent hyperlink between the threads to safe the form.

Leigh notes that light-driven motors is perhaps difficult to make use of although, as a result of they grow to be more and more unstable with extra pressure. “But challenges are there to be overcome,” Leigh says in an electronic mail. “It’s a wonderful demonstration of how molecular motors can be used for mechanically manipulating molecular units for synthesis.”

Ivan Aprahamian, a chemist at Dartmouth College who makes a speciality of molecular switches, says in an electronic mail that the work “will inspire the design of molecular machines that can pick up reactive threads from the solution, interlock them through their motion, and then release them to the environment.” That’s a aim Kathan says his lab is working towards.