Current projects in the Cremeens Lab focus on one basic question in the context of organic chemistry - “How does ‘it’ work, what is the mechanism?”. Please see below for more detail.
Physical Organic Chemistry Project:
“Combustion, Reaction Mechanisms, Dynamics… ”
Whether one is developing new technologies for combustion engines or new fuels for those engines, or whether one is trying to understand atmospheric chemistry and pollution, a detailed knowledge of their gas-phase reaction mechanisms is critical for understanding and possibly preventing problematic pathways. On-going discussions of non-statistical effects in reaction mechanisms have altered how experts view factors that control the outcomes of reactions. To develop the needed detailed knowledge and advance the development of cleaner energy technologies, much computational and experimental work needs to be done.
Historically, the theories and equations used to approximate reaction rates assumed a statistical distribution of energy or states. However, such approximations are not always appropriate. For example, upon considering the energy landscape of a reaction, one could draw an analogy to our natural landscape. Imagine that a skier on a hill top is akin to a molecule at a transition state; the skier will not necessarily follow the lowest potential energy path down the hill, rather, momentum affects the observed path. Deviations from a reaction path due to such motion effects are not easily accounted for with standard approximations. The Cremeens Lab developed an approach for scanning reactions with potentially interesting motions, after which we further assess how those motions are involved in the reactions and then go on to validate any non-statistical characteristics of the reaction mechanism.
Our Lab will employ computationally inexpensive quantum chemical calculations in conjunction with our method to assess the potential for non-statistical reaction dynamics in numerous of gas phase reactions from National Institute of Standards and Technology’s Chemical Kinetics Database. Ideally, we will scan the NIST database, identify potential non-statistical reactions, and then run expensive simulations on those reactions for computational validation. After such validation, experiments will be designed to test the predictions.
Methods: Synthesis, Spectroscopy, and Calculations
Small organic molecules for the physical organic chemistry project are synthesized via traditional organic synthesis, i.e. using inert atmosphere techniques, thin layer chromatography (TLC), column chromatography, gas chromatography—mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR) spectroscopy. Experimental observations are often compared to quantum chemical calculations using Gaussian and desktop workstations.
Support comes from Gonzaga University start-up funds, the Gonzaga Science Research Program, Gonzaga’s Department of Chemistry and Biochemistry, and in part by a grant to Gonzaga University from the Howard Hughes Medical Institute through the Undergraduate Science Education Program.
Acquisition of a CD spectrometer was supported by the National Science Foundation under CHE-0922945 (“MRI: Acquisition of a Spectropolarimeter: A Chiro-Optical Spectroscopy Workbench” $181,155; 2009-2012; PI: Cremeens with co-PIs Jeff Watson and Tommaso Vannelli.)