Crystals on the Move

In this project, funded by the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, Professor Anna D. Gudmundsdottir of the Department of Chemistry at the University of Cincinnati is analyzing how crystals respond to external stimuli such as light and mechanical force. These studies focus on producing motility or movement in crystalline materials using momentum generated by releasing a gas.

The mechanism is analogous to the operation of a gasoline engine. The response of crystals to external stimuli can be quite dramatic, as such crystals that can propel themselves over distances much larger than their own size, twist, coil, crawl, bend, fracture, or even shatter. Because dynamic crystals respond rapidly to external stimuli such as light, heat, and mechanical force, they have potential for use in various smart materials applications, such as sensors and actuators in industrial processes and devices.

The interdisciplinary nature of this research project provides broad educational training for students. Through this research, students will learn to solve demanding technical problems facing society. Emphasis will be placed on building an inclusive and diverse research team to work in the Gudmundsdottir laboratory, including high school and college undergraduate students from groups underrepresented in science.

Students will also be presented with educational activities geared towards their professional training.

The Gudmundsdottir research team will study the photodynamic and mechanical behavior of crystalline divinyl azide and ester azide derivatives. Upon light exposure, these substances dissociate to form molecular N2 gas and photoproducts. The physical properties of these crystals will be determined by acquiring their single crystal X-ray structures, indexing the crystals, and measuring their hardness.

In addition, the solid-state photoreactivity of these compounds will be determined by performing laser flash photolysis of nanocrystals to characterize the transients formed within the crystals. Further studies will determine the solid-state kinetics of these transients and identify their photo-products. Collectively, these data will be analyzed with an eye toward elucidating the detailed solid-state reaction mechanisms and toward explaining how the crystal lattice controls both the molecular reactivity and the macromolecular photodynamic behavior of divinyl azide and ester azide derivatives.

These studies of photo-mechanical response and molecular solid-state photo-reaction mechanisms will be supported by quantum mechanical modeling.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.