The Reactivity of Vinyl Nitrene Intermediates

University Of Cincinnati Main Campus, Cincinnati OH

Investigators

Abstract

With this award, the Organic and Macromolecular Chemistry Program supports Professor Gudmundsdottir of the University of Cincinnati whose research will focus on selectively forming, detecting and investigating the reactivities of vinyl nitrene intermediates in solution and in the solid state. Direct irradiation of vinyl azides yields azirine products that can be attributed to formation of singlet vinyl nitrenes or can come from concerted rearrangement of the singlet excited state of the vinyl azides. Similarly, direct photolysis of 2H-azirine derivatives forms singlet biradicals. In order to bypass the singlet reactivity of the vinyl azide and 2H azirine precursors, vinyl azide and 2H-azirine derivatives with build-in triplet sensitizers have been prepared. The triplet vinyl nitrene intermediates that are expected to form by photolysis of these vinyl azides and 2H-azirines will be characterized using laser flash photolysis and matrix isolation. A detailed picture of the reactivities and kinetics of triplet vinyl nitrenes in solution will be obtained. Preliminary results imply that laser flash photolysis of 2H-azirine derivatives that have a built-in triplet sensitizer permit direct detection of triplet vinyl nitrene intermediates. These results have opened up a new field in nitrene chemistry and intermediates that have not previously been characterized can now be investigated. The solid state reactivity of these vinyl nitrene precursors will be studied in order to understand how their reactivity is affected by surrounding crystal lattices. The long term goal is to render these intermediates stable to explore their physical properties. The investigations that are proposed will lead to full characterization of triplet vinyl nitrenes in argon matrices and in solutions. Since the chemical reaction pathways for these intermediates in solution and in the solid state are largely unknown, they will be studied and identified. Molecular modeling will be performed to aid in the characterization of these compounds and to explain the reactivity of these intermediates. Better insight into the reactivity of triplet vinyl nitrenes will allow for the design of stable triplet nitrenes. With this award, the Organic and Macromolecular Chemistry Program supports Professor Gudmundsdottir of the University of Cincinnati whose research will study triplet nitrene intermediates that have high spin properties and are therefore potential candidates for organic magnets. The quest for new organic materials with magnetic properties arises from their potential to provide new technological advantages for applications such as magnetic shielding, magneto-optical switching, and 'smart' materials. The proposed research will train graduate students to do fundamental research in physical organic chemistry. These graduate students will in turn train undergraduate students to do research and expose high school students to scientific research. Emphasis will be placed on attracting minority high school students to work on the proposed research.