RUI: Mechanisms, Kinetics, and Dynamics of Carbene Additions to Diarylcyclooctynes

Barnard College, New York NY

Investigators

Abstract

The Chemical Structure, Dynamics, and Mechanisms Program of the NSF Chemistry Division supports the research of Professor Dina C. Merrer in the Department of Chemistry at Barnard College. Professor Merrer and her students use a highly collaborative approach to investigate the mechanism for addition of carbenes to strained cyclooctynes. Carbenes are highly reactive groups with only two bonds to carbon instead of the usual four. Cyclooctynes are the smallest cyclic compounds which can accommodate a carbon-carbon triple bond yet still be stable at room temperature. These substances have relevance to chemical biology and materials science. The combination of carbenes with cyclooctynes produces chemical reactions with unusual features of reactivity. The project involves Barnard undergraduates in research activities at Barnard as well as at Colby College, UCLA, and the University of Wisconsin, Madison. Under development is a modular program on food chemistry for high school teacher professional development. This teacher development program is aligned with New York State K-12 science learning standards and partners with Barnard NSF-funded Noyes STEM Teacher Scholars and Washington Heights Expeditionary Learning School (WHEELS). This program serves as a model for a future science teacher professional development academy at Barnard, coordinated by Barnard's Education Program. The Merrer group studies the influence of nonstatistical dynamics on the mechanism of carbene additions to strained carbon-carbon pi bonds. Both experiment and theory are used to investigate dichlorocarbene and phenylchlorocarbene additions to dibenzocyclooctyne (DIBO) and dinaphthocyclooctyne (DINO). The objectives of this research are to: (a) investigate the effect of microwave heating in thermal bimolecular reactions of carbenes; (b) probe dynamically affected systems experimentally by entering the mechanistic sequence at a critical midway point; and (c) obtain spectroscopic and nanosecond kinetics data on these systems. Synthesis, steady-state photochemistry, product analysis, characterization, and calculations are carried out by undergraduates at Barnard College. Collaborative studies on matrix isolation spectroscopy, flash photolysis and quantum chemistry are carried out at the University of Wisconsin, Colby College and UCLA, respectively. Outreach activities to high-need New York City high school students and their teachers, including the beginnings of a science teacher professional development academy, are part of the funded project.