Bucknell Chemistry Professor Awarded Kaufman Foundation Grant to Develop Switchable Molecular Systems

Bucknell University Professor Hasan Arslan, chemistry, has been awarded a $100,000, two-year Charles E. Kaufman Foundation Integrated Research-Education grant to support a research project with Bucknell undergraduates titled "Switchable Supramolecular Hosts for Catch-and-Release Systems."

The Kaufman Foundation provides support for research that focuses on direct engagement of undergraduate students alongside innovative scientists engaged in basic, fundamental research in Pennsylvania.

At its core, Arslan said his project is about fundamental molecular behavior.

"We are trying to understand how molecules interact with each other," he says. "In the systems that we work with — and the subject of this proposal — the hosts are typically molecular macrocycles or cages, which are compounds that have a molecular cavity. They can host other molecules in that cavity given the right conditions; we call them guests."

Arslan compares the fit between "host" and "guest" to a familiar mechanism: "It's like a lock-and-key mechanism. The better the match, the stronger the interaction," he says. "They're seen in living systems, like enzymes. The enzyme combines with the substrate of the right shape and size, and is held together by intermolecular forces."

The project seeks to better understand how changes in molecular structure affect binding strength in catch-and-release systems and to develop a reversible molecular switch designed to catch and release polycyclic aromatic compounds (PACs) — environmental pollutants commonly found in soot and oil spills. Arslan said the project has multiple goals, starting with designing new molecular hosts and building in features that allow researchers to control binding.

"The first is to explore newer systems — specifically designing some new hosts, which will build upon my earlier work," he says. "We want to make them more readily switchable to control their properties. You can imagine a host having stronger affinity towards a guest in one state, and weaker affinity in another. By switching between these two states — which can be done using various external stimuli such as light, acid/base, or electricity — we can change its shape or electronic properties. Ultimately, we aim to achieve precise control over host-guest interactions."

That kind of control could support practical applications over time.

"The way I think of practical applications, down the road, with an optimized system, we can have a host that can be used for environmental remediation — addressing environmental pollution," Arslan says. "If you have selective receptors that can bind PACs, you can extract them out of the environment efficiently. The switching becomes beneficial for regenerating and reusing our hosts."

Student involvement is built into the grant’s research and education model. The proposal calls for two students to be working on the project per summer, and up to 16 per academic year in the organic chemistry teaching laboratory. He hopes the project will help expand student access to authentic research experiences, and will serve as a launch point for continued work.

"My hope is to use this as more of a springboard where the research will continue beyond the grant period," he says. "My goal is to expand our research approach — one that emphasizes the scientific process and innovation — to the teaching laboratory. Students will work together on a project toward a new target, devising several synthetic steps using molecular design instead of carrying out disjointed experiments, which is the more traditional model used in most organic chemistry teaching labs."

Students working on the project will gain experience with instrumentation used routinely in modern chemistry research labs, including nuclear magnetic spectroscopy resonance (NMR) and mass spectrometry. This shift toward a Course-Based Undergraduate Research Experience (CURE) is about more than just lab techniques, Arslan explains. "It's about student success. Studies have shown that CUREs can significantly increase retention in STEM and improve critical thinking," Arslan says.

A distinctive element of the project is using electrical input as one of the switching mechanisms.

"For these switches, I want one of the inputs to be electrochemical; by applying a specific potential, we can control the redox state of the host," Arslan says. "These switches also have the potential to yield new electrochromic materials — substances that undergo a reversible color change in response to an electrical stimulus. Such materials could be used in smart-glass technologies for future energy-efficient light-dimming applications."

Arslan emphasizes the grant was awarded because of the project’s dual purpose of both research and student involvement.