Professor Paul Bonvallet
General Area of Research:
Synthesis and binding of crown ethers
Crown ethers are ring-shaped receptors that capture certain chemical species within their electron-rich cavity. Small crown ethers typically bind with metal cations, while bigger ones can encircle entire organic compounds. This motif is similar to the interactions between many biological molecules in which the binding of two separate chemical components occurs through intermolecular forces (hydrogen bonding or electrostatic attraction, for example) rather than the formation of covalent bonds. The strength of the binding is determined by appropriately matching the size, shape, and electronic nature of the "host" and "guest."
Much of the research in the Bonvallet laboratory involves predicting and measuring the binding strength (equilibrium constant) between bound and unbound chemical species. The binding stoichiometry – the number of guests interacting with each host – can be determined as well. The measurements are made with NMR (nuclear magnetic resonance) spectroscopy, UV-visible spectroscopy, and ITC (isothermal titration calorimetry). Crown ethers can be employed in chemical sensors and other stimulus-responsive materials, but also serve as scaffolds for complex molecules with mechanically interlocked parts.
Several crown ethers that we hope to test, in addition to many guest compounds, have either been prepared or can be synthesized quickly. The goal for this summer is to investigate the strength of host-guest binding using a suite of instrumental methods. Once complete, this investigation will guide future efforts in an ongoing project on light-emitting polymers that contain crown ethers.
Skills / Classes Required:
Previous experience with organic chemistry is helpful but not required. Students need to be creative, motivated, and attentive to detail. Problem-solving skills are essential.