The guest speaker for the January 28th Chemistry & Biochemistry Colloquium will be Prof. Adam Braunschweig: Determinants of rates and selectivities in mechanically driven pericyclic reactions Dr. Braunschweig is a Professor of Chemistry at Hunter College, CUNY.

Abstract: Mechanochemistry, which uses force rather than heat, light, or electrical potential, to drive chemical reactions, could transform entirely how chemicals are produced, while significantly reducing the energy demands and waste production involved in chemical manufacturing. However, challenges in quantifying how force affects bond formation have hindered the widespread adoption of mechanochemistry. This lecture describes how emerging analytical methods involving parallel tip-based arrays are used to determine reaction rates, activation energies, and activation volumes of force-accelerated [4+2] Diels-Alder cycloadditions between surface-immobilized anthracene and four dienophiles that differ in electronic and steric demand. The dependence of rates on pressure are unexpectedly strong, and significant differences are observed between the dienophiles. Multiscale modeling demonstrates that, in proximity to a surface, mechanochemical trajectories exist that are distinct from solvothermal reactions or those carried out under hydrostatic pressure. These results provide a new framework for anticipating how experimental geometry, molecular confinement, and directed force contribute to mechanochemical kinetics, providing a pathway toward realizing the benefits of solvent-free, sustainable mechanochemical syntheses. 

BIO: Adam Braunschweig is a professor of nanoscience at the Advanced Science Research Center of the City University of New York (CUNY) and a professor of chemistry at Hunter College, CUNY. His research group develops new lithography methods for printing soft materials, and broad-spectrum antivirals. Recently they have begun investigating mucus as an inspiration for advanced materials, and Prof. Braunschweig holds the world’s largest collection of secreted animal mucus in a ‒80 ^oC freezer outside his office.