When preparing something delicious in the kitchen, you might blend ingredients for a smoothie, mix flour and eggs for a cake, or knead dough to achieve the perfect texture. No need for fancy substances or extreme conditions—a bit of mechanical force does all the work.

“Chemistry is notoriously known to create large amount of toxic waste and sustainable technologies are urgently needed,” emphasizes Professor Riina Aav, Head of the Supramolecular Chemistry Group at TalTech. According to her, scientists have now learned to use mechanochemical approach to build complex molecules. “Instead of boiling dangerous mixture of chemicals dissolved in corrosive mineral acids using complicated lab setups, they simply shake, grind and mix solid materials—like making cookie dough or a smoothie, but with a clever trick,” explains doctoral student Elina Suut-Tuule, the lead author of the study.

A new kind of “pumpkin recipe”

Traditionally, making special molecules from pumpkin family (cucurbitaceae), such as biotin[6]uril, which has a hollow cavity capable of trapping smaller molecules, used to be a long and cumbersome procedure. “Previously, its synthesis required large volume of strong acid as solvents, long reaction times and generated significant amounts of hazardous waste. However, biotin[6]uril is useful for applications in medicine as transmembrane carrier of anions and it may act as a molecular receptor elsewhere, therefore its preparation is necessary,” Aav explains.

The TalTech supramolecular chemistry researchers—comprising Riina Aav, Elina Suut-Tuule, Eve Schults, Tatsiana Jarg, and Dzmitry Kananovich—have found a cleaner, faster, more efficient and environmentally friendly way to produce biotin[6]uril using mechanochemistry.

“This method relies on utilizing mechanical force to mix solid chemicals and triggering reaction between them to replace the previous need of boiling hazardous mixtures,” notes senior researcher Dzmitry Kananovich. “Previously, grinding under controlled conditions in research laboratories has been inadequate, but this technical issue has now been resolved with the introduction of laboratory ball mills.”

This means the solid ingredients are placed in a ball mill, where they are mixed together and then transferred to an oven to let the chemistry do the rest. “It’s like making cookie dough—where the right ingredients, combined with some mixing and heating, turn into something completely new,” explains master's student Eve Schults.

What does “molecular baking” really look like?

To better understand the process, the researchers suggest imagining the shaping of a perfectly formed pumpkin from tiny molecular building blocks.

The process starts with two main ingredients: D-biotin (vitamin B7, found in many foods) and paraformaldehyde. “Previously, assembling these building blocks required large amount of acid, but now just a few drops are added—about 200 times less—like a carefully measured ingredient in a recipe,” says Suut-Tuule.

Then everything is placed into a ball mill, which shakes and grinds the ingredients together. This step ensures that the vitamin molecules start assembling in the correct way. Once the grinding is complete, the milled mixture is transferred to an incubator—a molecular oven. With the right temperature and time, the molecules self-organize and “bake” themselves into a perfectly shaped molecular pumpkin—biotin[6]uril. Suut-Tuule and Aav emphasize that thanks to “molecular baking,” chemistry has become faster, cleaner, and more sustainable—one tiny molecular pumpkin at a time!

Grinding for a greener future?

What excites the TalTech researchers the most is that the mechanochemical approach isn’t limited to making just tens of grams of biotin[6]uril. It has the potential to revolutionize how everything is produced from pharmaceuticals to materials in kilograms and tons. This gives a glimpse of how much cleaner our environment could become if pharmaceutical and chemical companies could manufacture life-saving drugs and other compounds without producing mountains of toxic waste. Or if industries could develop new and sustainable materials simply by grinding the right ingredients with a bit of mechanical force. “Shaking, mixing, and grinding aren’t just for the kitchen—they may be the secret processes that guide chemistry toward a cleaner and greener future.”

Read more about the TalTech researchers' work on developing more resource-efficient chemical methods at SOURCES, the Estonian Centre of Excellence for Circular Economy, in the international journal ChemSusChem – Chemistry-Sustainability-Energy-Materials.