RUI: Studies of Condensed-Phase Effects on the Structural Properties of Molecular Complexes

University Of Wisconsin-Eau Claire, Eau Claire WI

Investigators

Abstract

In this project supported by the Chemical Structure, Dynamics and Mechanisms A Program of the Division of Chemistry, Professor James Phillips and his undergraduate research students seek to understand how two interacting molecules (a molecular complex) may change their structure or the nature of their interaction depending on whether they are in the gas phase (i.e., surrounded by essentially nothing), or in the condensed phase (surrounded by solvent molecules or other molecular complexes). The Phillips' research group uses infrared spectroscopy to probe the vibrational motions of molecular complexes in different environments at low temperatures (5 to 100 Kelvin, or -450 to -280 Fahrenheit). The team is also performing theoretical calculations (quantum chemistry models) to further understand the experimental observations. The University of Wisconsin - Eau Claire is a low-cost, public institution with a student body that is about 60% female and 50% low-income/first generation students. This research program actively involves these underrepresented groups. Moreover, the Chemistry Department at the University of Wisconsin - Eau Claire has embarked upon an integrated effort to actively recruit students from underrepresented groups, based in part on an NSF-Research Experiences for Undergraduates (REU) site. The intellectual goals of the project are twofold, and are pursued through a combination of experiments and modeling. From a fundamental standpoint, the aim is to identify and characterize systems prone to condensed-phase structural change, and thereby challenge long-held, fundamental principles of chemical bonding. Specific systems that are studied in this regard are imine-HCl complexes, which offer snapshots of an acid-base reaction in progress; as well as carbon monoxide-BX3 complexes (X = F, Cl, Br), for which theory predicts two distinct, stable structures with different bond distances. Additional target systems have potential applications, because the ability to manipulate a chemical structure via some external stimulus is the key underlying design feature for any nanotechnology device. Complexes involving nitrogen donors (e.g., pyridine, C5H5N) with Group IV metal acceptors (MX3R: M = silicon, germanium; X = fluorine, chlorine; R = carbon-based group) have the desired molecular architecture for such applications. The first step towards gauging their suitability is to assess their tendency to undergo structural change.