12/19/16 - 9:45 AM to 11:00 AM
Carson J. Bruns, Ph.D.
"Ring-and-String Approaches to Chemical Assembly"
Threading a string through the eye of a ring is not a trivial task if the ring and string are both molecules. Since we lack the dexterity on the nanoscale to use mechanical force in order to guide a molecular string through the eye of a ring (as we do on a macroscopic scale), we must instead rely on chemical interactions and reactions that cause ring and string molecules to assemble themselves into threaded structures, in spite of their random Brownian movements. If the ring becomes permanently trapped on the string, these two component parts are said to share a mechanical bond. I am interested in uncovering ways in which this non-canonical bond can give rise to emergent types of chemical structures, dynamics, and functions. In this seminar I will describe how (i) the efficiency of molecular ring threading can be controlled by nanoscale confinement within self-assembled molecular flasks, and also how mechanically bonded ring-and-string molecules known as rotaxanes can be fashioned into (ii) “molecular muscles” that expand and contract in response to electrochemical and thermal stimuli, (iii) oligomers and polymers with well-defined, folded superstructures akin to proteins, (iv) stimulus-activated probes for magnetic resonance detection technologies such as NMR and MRI, and (v) the first protein bioconjugates with mechanical bonds. Although it is not a chemical bond, this research suggests that the mechanical bond is equally capable of influencing the structures, dynamics, and functions of molecular materials.
Bruns is the Miller Research Fellow at the University of California, Berkeley, working with Professor Matthew Francis. He was also a post-doctoral fellow with Professor Samuel Stupp and J. Fraser Stoddart at Northwestern University. He earned his bachelor's degree in chemistry from Luther College, and his doctorate in organic chemistry from Northwestern University.
Event DetailsLocation: 401/402 Walter LibraryHost: Professor Philippe BuhlmannSpeakers:
- Carson J. Bruns, Ph.D.
- Department of Chemistry
- University of California