Researchers develop a tool to neutralize chemical weapons using rare-earth elements

Tb-CU-10 Metal Organic Framework. Credit: Victor Quezada-Novoa
Concordia researchers are looking into the potential uses of a particular type of compound known as metal-organic frameworks. The new microscopic structure can be used to quickly mitigate chemical weapons when it is exposed to ultraviolet light.

MOFs can be described as artificially-created hybrid networks of metal clusters that are bound together by organic linkers, ligands. They are porous and often have an open face. They can be used in many different applications, from water remediation to drug delivery, and are very versatile depending on the materials involved.

A new paper on one such MOF was written by Victor QuezadaNovoa, a Ph.D. candidate in chemistry and AshleeHowarth, assistant professor of biochemistry and Concordia University Research chair in Metal-Organic frameworks in the Faculty of Arts and Science. They present the design and synthesis a new MOF made up of rare-earth metals, ytrium and tritium and bound with an organic linker. The structure was named RE-CU-10 (RE = rare earth, CU = Concordia University).

Their findings were published in Chemistry of Materials. The paper was co-authored by Hatem Titi from McGill University and Amy Sarjeant of Bristol Myers Squibb.

Fast-acting oxygen species

Quezada-Novoa is the lead author. The linker, which is a rectangular tetratopic-pyrene-based, ligand has a special core that interacts ultraviolet light. This produces an extremely reactive, but short-lived oxygen species that causes chemical warfare agent sulfur mustard to change. It is better known for being the World War I blistering agent mustard gasoline and is still in stock.

A new metal-organic framework with Victor Quezada-Novoa & Ashlee Howarth

Quezada Novoa worked at Concordia's Howarth Lab. He suspended his MOF inside a small glass vial that contained a milliliter methanol. The researchers added 23 microlitres sulfur mustard simulant to the vial and exposed it to a UVLED photoreactor. They found that the MOF oxidized effectivelyand thus detoxified the chemical warfare agent simulant. This process took only 15 minutes and achieved a 50 percent conversion to less toxic products in three and a quarter minutes.

Quezada Novoa states, "We showed that the material we synthesized works quickly and is in fact the fastest catalytic material to be reported using the reaction setup."

It has the potential for scaling up, and we hope to one day test this MOF at a military laboratory. This is our goal considering that there are still thousands of liters stockpiled sulfur mustard all over the globe.

Howarth points out how Quezada-Novoa is different from other MOF research because it uses rare-earth elements, elements that are found all over the world, including in northern Canada. These elements have vital industrial uses from missile guidance systems to smart phones.

Howarth says that although researchers have considered using MOFs to neutralize chemical weaponry before, they have never used rare-earth MOFs with multinuclear Cluster Nodes. "Victor created a new material that has specific features that are unlike any MOFs previously used."

Flexible to meet many needs

The Howarth Lab's main research focus is on metal-organic frameworks, and their many applications.

She says that each student in the group has a different goal. "And while they're exploring different avenues in their research, they're all working on molecular structures that can be tuned and designed into virtually any type of chemistry depending on the final application.

Continue reading A rare feat: Material protects both biological and chemical threats

More information: Victor Quezada-Novoa et al., Building a Shp: A Rare-Earth MetalOrganic Frame and Its Application In a Catalytic Photooxidation Resaction, Chemistry of Materials (2021). Information from Chemistry of Materials Victor Quezada-Novoa et al., Building a Shp: A Rare-Earth MetalOrganic Framework, and Its Application In a Catalytic Photooxidation Reaction. (2021). DOI: 10.1021/acs.chemmater.1c00917