Published January 30, 2014
The sponges of the future will do more than clean house.
Picture this, for example: Doctors use a tiny sponge to soak up a drug and deliver it directly to a tumor. Chemists at a manufacturing plant use another to trap and store unwanted gases.
These technologies are what UB faculty member Jason Benedict had in mind when he led the design of a new material called UBMOF-1. The material — a metal-organic framework, or “MOF” — is a hole-filled crystal that could act as a sponge, capturing molecules of specific sizes and shapes in its pores.
Swiss cheese-like MOFs are not new, but Benedict’s has a couple of remarkable qualities:
Benedict’s team reported on the creation of the UBMOF on Jan. 22 in the journal Chemical Communications. The paper’s co-authors include chemists from UB and Penn State Hazleton.
“MOFs are like molecular sponges — they’re crystals that have pores,” explains Benedict, assistant professor in the Department of Chemistry.
“Typically, they are these passive materials: They’re static. You synthesize them and that’s the end of the road,” he adds. “What we’re trying to do is to take these passive materials and make them active so that when you apply a stimulus like light, you can make them change their chemical properties, including the shape of their pores.”
Benedict is a member of UB’s New York State Center of Excellence in Materials Informatics, which the university launched in 2012 to advance the study of new materials that could improve life for future generations.
To force UBMOF-1 to respond to ultraviolet light, Benedict and colleagues used some clever synthetic chemistry.
MOF crystals are made from two types of parts — metal nodes and organic rods — and the researchers attached a light-responsive chemical group called a diarylethene to the organic component of their material.
Diarylethene is special because it houses a ring of atoms that is normally open but shuts when exposed to ultraviolet light.
In the UBMOF, the diarylethene borders the crystal’s pores, which means the pores change shape when the diarylethene does.
The next step in the research is to determine how, exactly, the structure of the holes is changing and to see if there’s a way to get the holes to revert to their original shape.
Rods containing diarylethene can be forced back into the “open” configuration with white light, but this tactic only works when the rods are alone. Once they’re inserted into the crystal, the diarylethene rings stay stubbornly closed in the presence of white light.