Chemistry Colloquium Program

"New NLO Materials: Design, Synthesis, and Crystal Growth"

Nonlinear optical (NLO) materials are critical in generating coherent light through frequency conversion, e.g., second harmonic generation (SHG). From the ultraviolet (UV) to the infrared (IR), NLO materials have expanded the range of the electromagnetic spectrum accessible by solid-state lasers. Wavelengths where NLO materials are still needed include the UV (~200 - 400nm) and deep UV (< 200nm). Coherent deep-ultraviolet (DUV) light has a variety of technologically important uses including photolithography, atto-second pulse generation, and in advanced instrument development. Design strategies will be discussed, as well as synthetic methodologies. In addition, the crystal growth, characterization, and structure-property relationships in new UV and DUV NLO materials discovered in our laboratory will be presented. Finally, our crystal growth capabilities and recent crystal growth of functional materials will be described.

"Ligand design for earth-abundant transition metals to model active sites and promote cooperative catalysis"

Many processes of significant importance to the ongoing development of the clean energy economy depend on transition metals, including as catalysts for fuel production and for charge storage in batteries.  Optimizing these processes, especially so that they can be carried out with earth-abundant transition metals, requires careful control of the metal’s environment.  This can be accomplished through ligand design, including the design of ligands that incorporate cooperative properties.  Much of our work broadly focuses on developing ligands, reagents, and transition metal complexes which have potential applications in, and/or provide fundamental insight into, these types of processes.  This includes (1) first-row transition metal complexes of pyrazine(diimine) ligands which catalyze hydrogen evolution through ligand-centered cooperative process; (2) bioinspired chelators with tunable selective binding that control the redox properties and spin states of coordinated transition metals through steric effects; and (3) newly developed pathways to install terminal methylidyne ligands as models for processes on the surface of heterogeneous transition metal catalysts.

About the Speaker: Sid Creutz is an Associate Professor at Mississippi State University. His group’s research focuses on synthetic inorganic chemistry, including organometallic chemistry, bioinorganic chemistry, and semiconductor nanomaterials synthesis.  Research is funded by the U.S. National Science Foundation, National Institutes of Health, and the American Chemical Society. 

"Saloplastics: Processing Blends of Charged Polymers with Salt"

Charged polymers, or polyelectrolytes, are widely used in technology. Mixtures of oppositely-charged polymers spontaneously form complexes, which can be solid-like or liquid-like. In either case, salt solutions can be used to break the electrostatic crosslinks between polymers and therefore soften them, much like heat softens thermoplastics. These polyelectrolyte complexes, PECs, offer a wide range of applications and morphologies. This talk will focus both on the mechanisms controlling the mechanical properties of PECs and on some of their new useful applications.

"A conceptual approach to understanding complexity using the tools of theory and simulation"

I will discuss how simple concepts in theoretical physical chemistry can be used to understand complex phenomena in the condensed phase.  I will emphasize Coulombic systems and discuss phenomena ranging from fundamentals of solvation to collective effects such as (anomalous) screening.  I will discuss the role of the coupling between short-range and long-range interactions to construct models of reduced complexity to connect with experimental observations of complex phenomena in liquids.