2008 Spring Symposium
Harold H. Kung
Chemical and Biological Engineering Department
Northwestern University, Evanston
IL 60208–3120, USA
Abstract — In nature, enzymes function effectively under mild conditions of near neutral pHand room temperature using common organic functional groups such as amines,hydroxyls, and carboxylic acids, which, when used outside the enzyme environment,exhibit activities many orders of magnitude lower. It is understood that the enzymeprotein provides an environment that is conducive to cooperative effect among the groupsand hydrophobicity at the active center. In contrast, catalysis in abiotic systems seldomutilized such functions, especially heterogeneous catalysis. Instead, they rely on harshreaction conditions of elevated temperatures and pressures, and/or strong acids and bases,with the consequence of sacrificing selectivity. Recently, advances in catalyst synthesistechniques make it increasingly possible to design and synthesize abiotic systems thatpossess multiple functionalities to achieve cooperative catalysis.
Examples includecooperative acid-base catalysis in which a Lewis acid and a basic function are anchoredon a silica surface, including SBA-15 and coordinated metal ions on the periphery of adendrimer. We have investigated using nanocage structures to examine the effect ofenvironment and discovered evidence of the “pKa shift” effect of amines groups insidethe cage, primarily due to electrostatic repulsion. These and other examples will bediscussed.
Speaker’s Biography — Dr. Kung is Professor at the Department of Chemical and BiologicalEngineering, and Director of the Center for Energy Efficient Transportation atNorthwestern University. His research goal is to search for and develop the underlyingchemical and engineering principles governing catalysis, especially regarding activity andproduct selectivity, and to make use of such knowledge to design novel and efficientcatalysts and processes.