The Chemical Structure, Dynamics and Mechanisms Program supports Professor Paul G. Williard at Brown University who will provide greater understanding of the solution structure and reactivity of important organometallic reagents while further expanding the utility of the Diffusion-Ordered NMR Spectroscopy (DOSY) method. Professor Williard describes the continued development and application of DOSY with respect to understanding aggregation of organometallic reagents used broadly in synthetic chemistry and outlines its extension to other unrelated systems showing the range and potential for the method. The research proposed includes topics such as, ligand and solvent exchange processes in organolithium reagents, diffusion across membranes, examination of membranes for battery applications, mixed aggregates, the chiral memory effect, and the selectivity of deprotonation reactions. The examination of mechanistic details has the potential to form the foundation for new chemical transformations with great societal impact, for example, drug synthesis, novel materials for energy applications and less negative environmental impact. The research will develop an important new method designed to extend the use of nuclear magnetic resonance spectroscopy beyond the traditional bounds of structure elucidation/structure determination and into the realm of utilizing this powerful spectroscopic technique to determine size and molecular weight parameters of multicomponent mixtures.
Professor Paul G. Williard will help to solve problems of national importance in the realm of energy and fuel production. Broader impacts include international collaborations, working with inner city public high schools, and attracting underrepresented minority undergraduate and graduate students to work in his laboratory, liaising with the Brown University Leadership Alliance Program and the NSF ADVANCE Program.
Overall my research program targets the acquisition of structural information of reactive intermediates that underpin all modern synthetic organic chemistry. It is noteworthy that the extant models for such reactive intermediates are based upon largely on unverified models with little if any experimental structure validation. Support from this research grant has lead to the following specific discoveries: the solid-state structures of unsolvated, hexameric cyclopentyllithium and tetrameric cyclopentyllithium tetrahydrofuran solvate were determined by single-crystal X-ray diffraction, the solid state structure of chiral lithiated amide bases synthesized from (S)-valine were determined by single-crystal X-ray diffraction and also characterized by a variety of NMR experiments including diffusion-ordered NMR spectroscopy (DOSY) with diffusion coefficient-formula weight correlation analyses, an the experimental technique that couples advanced NMR techniques with the investigation of viscosity, a basic physical property based on molecular structure that we use to determine molecular weight of componds in solution was developed, and we reported the synthesis and structural characterization of a new Au22 nanocluster that is unprecedented in atom-precise gold nanoparticles and can be considered as potential in-situ active sites for catalysis for example in the conversion of CO2 to acrylic acid. Overall results of this research program permit other chemists to greatly improve the efficiency of synthesis of both bulk scale commodity chemicals and fine pharmaceuticals. Ph.D. students supported and trained in this program are now pursuing research in leading positions in both industry, e.g. Boston Power Inc., and government labs, e.g. Argonne National Lab, in the development of next generation lithium ion batteries for automotive and electronics industries. In conjunction with this research project, I developed a freshman only seminar specifically for non-science concentrators to discover and discuss the origin, background and consequences of our current notion of the shapes and structures of atoms, molecules, nanoparticles, proteins and polynucleotides. This course is being developed for web access and is designed specifically to introduce the fundamental concepts of the shape and characterization of the structures of molecules to students who have previously expressed in STEM relater subjects. An outreach program to primarily undergraduate minority institutions has begun in collaboration with this project and the first exchange of personnel between Brown University and Claflin College has been initiated.
