Professor Johnson and his students will investigate microwave flash pyrolysis (MFP), a method developed at UNH. The MFP method greatly extends the range of microwave synthetic chemistry into high temperature regimes; this research will lead to the discovery of new high-energy chemical reactions and a greater understanding of microwave-induced chemical reactions on solid surfaces. Chemical functionalization of graphite, carbon nanotubes and other materials by MFP methods will also be explored. Diverse aspects of pericyclic reactions will be studied, using theory to guide experimental studies. Pericyclic reactions have been commonly applied to make or break molecular rings. In this project, the novel concept of dehydro pericyclic reactions, which involve unusually strained and reactive rings, will serve as a basis for the discovery of new chemical processes. In one additional component of this project, the reactions of ozone with carbonyl compounds will be investigated. Ozone is a highly reactive and short-lived substance. Planned research will lead to new understanding of atmospheric ozone chemistry, and may have applications in organic synthesis. In a collaborative project with Professor William Bailey at the University of Connecticut, the PI and his students will create computational models for carbenoid reactions, probing critical aspects of mechanism and stereochemistry. New reactions, methods and materials discovered in this work will have broad applications in organic synthesis and materials science. Planned research will serve as professional training for graduate and undergraduate students. In addition to this research, Professor Johnson will develop an outreach program to help high school teachers enhance their chemistry curriculum with computer molecular modeling.
This grant period was marked by advances in many important mechanistic problems in chemistry. In this work, sophisticated quantum mechanical models are used both to predict new chemical reactions and to understand the mechanism of known processes. A new and broadly applicable theory was developed based on electron transfer to predict selectivity in polar organic reactions. This theory is easily applied with modern chemistry software and has the potential to be widely applied in designing the synthesis of complex molecules. Models were created for diverse important reactions including photochemical CO2 reduction, cyclopropyl carbenoid ring opening, the dimerization of allenes and many cycloaddition reactions. Models for complex reactions in natural product synthesis were developed as a collaboration with a research group at Boston University. The "dehydropericyclic" concept, developed in this work was reviewed and applied to reactions that generate high energy transient intermediates. This research reinvigorated an important field of carbocation chemistry with the discovery of new superacid catalyzed rearrangements of aromatic compounds and the first demonstration that chemical microwave reactors can be used for this type of chemistry. Research in this project led to the development of a highly efficient syntheses for quaterrylene, an important substance in materials science, which has applications in molecular electronics and photovoltaic devices. This has been an exciting time in the PI’s research group with a strong theme of scientific discovery and synergy between theory and experiment.
