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Tiny water-based reactors could help pharmaceutical industry avoid toxic solvents

Researchers at Rice University have developed a new method for performing chemical reactions using water instead of toxic solvents. The scientists created microscopic reactors capable of driving light-powered chemical processes by designing metal complex surfactants (MeCSs) that self-assemble into nanoscale spheres called micelles. This innovation could drastically reduce pollution in industries including pharmaceuticals and materials science, where harmful organic solvents are often necessary.

The new micellar technology represents a step forward in sustainable chemistry. These self-assembled micelles form in water, where their hydrophobic cores provide a unique environment for reactions, even with materials that are typically insoluble in water. The research team led by Angel Martí, professor and chair of chemistry at Rice, demonstrated that this system can efficiently perform photocatalytic reactions while eliminating the need for hazardous substances. The study is in Chemical Science.

"Our findings show how powerful molecular design can be in tackling chemical sustainability challenges while maintaining high chemical performance," Martí said. "We've created a tool that could transform how chemical reactions are performed, reducing environmental harm while increasing efficiency."

How the discovery works

Surfactants are molecules with a dual nature: One part is attracted to water, while the other repels it. When added to water, they naturally form micelles or tiny spheres where the water-avoiding parts gather in the center, creating a small reaction space. The scientists modified these surfactants by adding a light-sensitive metal complex to their structure, making the MeCSs.

The researchers tested different versions of the MeCSs by altering the length of their hydrophobic (water-repelling) tails. They found that these molecules could form micelles as small as 5–6 nanometers, much smaller than those in similar systems. The team used these micelles to perform a photocatalytic reaction, achieving high yields without needing harmful solvents.

"These micelles act like tiny reaction vessels," said Ying Chen, first author of this study and a doctoral student in chemistry at Rice. "They enable chemical transformations that wouldn't normally work in water while being more sustainable than traditional methods."

Many chemical processes in manufacturing and research rely on organic solvents, which are harmful to the environment and expensive to handle safely. The development of photoactive water-based micelles capable of driving chemical reactions offers a safer, greener alternative. Additionally, the system can be reused, improving its cost-effectiveness and environmental footprint.

The study was co-authored by Shih-Chieh Kao and Julian West of Rice's Department of Chemistry; Asia Matatyaho Ya'akobi and Yeshayahu Talmon of the Technion-Israel Institute of Technology; and Thao Vy Nguyen and Sibani Lisa Biswal of Rice's Department of Chemical and Biomolecular Engineering.