Shine a Light

York University chemists have invented a new fluorescence-based method for accurately determining the strength of a range of Lewis acids that could one day be used to help purify pharmaceutical drugs, improve industrial processes and explore next-generation technologies.

As important fundamental chemicals, Lewis acids are electron-pair acceptors, which the York scientists have elucidated with their groundbreaking work. They believe their fluorescent Lewis acid-base adduct (FLA) method to be the first of its kind to quantify the strengths of a wide variety of Lewis acids by providing the ability to visually observe differences. They expect this technique to replace the widely used Gutmann-Beckett method, which is prone to errors. The finding, recently published in the scientific journal Chem, could lead to improved and cheaper processes for the pharmaceutical and chemical industries.

“The pharmaceutical industry is always looking for optimized processes to make new drugs and find new chemicals,” says Thomas Baumgartner, a professor in the Department of Chemistry, Faculty of Science, and Canada Research Chair in Sustainable Organomain Group Materials, who co-led the study involving a team of six York University researchers. “Our method provides a valuable new tool to help develop these processes.”

Measuring the Lewis acidity of molecular species is important because it allows chemists around the world to establish the utility of new compounds to facilitate chemical transformations for a range of applications.

“Until now, there has been no unifying thread to determine the strength across different species,” says Christopher Caputo, an assistant professor in the Department of Chemistry and Canada Research Chair in Metal-Free Materials for Catalysis, who served as the York study’s joint leader.

“Some Lewis acids are charged, some are neutral, some are based on metals, some are based on non-metals, and they cover the entire periodic table. With our method, we can compare across all these different species and across the periodic table. As new chemistry and new Lewis acids are developed, our method allows you to quantify and compare all the strengths across the board, which could be very impactful.”  ■