With the support of the Organic Dynamics Program in the Chemistry Division, Professor Malcolm Forbes of the Chemistry Department at the University of North Carolina- Chapel Hill will investigate several new areas in macromolecular, supramolecular, and biological photochemistry. In particular, Professor Forbes seeks to understand how random and block copolymers degrade in solution, and to probe the dynamics of novel main chain polymeric free radicals. New linear and cyclic models for these dynamics, which manifest themselves as alternating line widths as a function of temperature, will also be synthesized and explored. Diffusion of free radicals will be probed inside new supramolecular structures such as polysomes, surfactant-stabilized nanocrystals, and CO2-based reverse micelles. Advances in the theory of mobile spin correlated radical pairs via the micro-reactor model, as well as computational studies on radical structures, will help drive new experiments and syntheses. Finally, two projects in mechanistic photobiology will begin, (1) investigation of model systems for proton-coupled electron transfer reactions in Photosystem II, and (2) the degradation of UV protectant compounds called kynurenines found in the human eye lens.
Research by Professor Forbes at the University of North Carolina- Chapel Hill will provide a fundamental understanding of free radical reactions and photochemistry that is essential to addressing problems such as energy storage ( photosystem II) and the effects of biological radical formation and damage. The proposed research closes the loop from the basic science of these events to solving long term questions of great importance. The research trains researchers in small molecule and polymer synthesis, structural analysis, photochemistry and laser spectroscopy, magnetic resonance (including microwave engineering), molecular and macromolecular dynamics, surface chemistry, and computational chemistry. There are few laboratories in the U.S. where all of these activities take place under one umbrella research program and students at all levels are well prepared with a solid foundation in many aspects of quantitative physical organic chemistry. Professor Forbes continues to build on his strong track record for international collaboration, with active projects in six different areas with researchers from four different countries. Extensive collaborations both nationally and internationally make his laboratory an international center for basic radical-related research.
Free radicals are highly reactive intermediates in many chemical and biological processes. They are involved in the synthesis and degradation of polymers and plastics, in the primary events of plant photosynthesis, and in oxidative stress associated with heart disease and hypertension. In the Forbes laboratory, we study free radical chemistry using a variety of direct and indirect spectroscopic methods, including fast time scale pulsed laser spectroscopy coupled to magnetic resonance detection for structural characterization of the intermediates and to obtain information about their lifetimes (reaction kinetics). Activities during our 2008-2011 grant period encompass the following areas: 1) spectroscopic properties of spin correlated radical pairs (SCRPs) in confined media, 2) polymer degradation, including macromolecular radical dynamics of acrylic copolymers and model systems, 3) elucidation of photochemical mechanisms, and 4) characterization of novel radical structures. International collaborations with scientists from Russia, Japan, Argentina and Brazil have been nurtured, and new domestic collaborations have recently formed. Our laboratory provides the training ground for scientists at many levels, from an ACS Project SEED student (a high school junior) to short–term senior scientists from overseas. From 2008 to the present, 11 undergraduates have participated in the program, of whom 4 have authored papers and another 6 have obtained publishable results to appear in future papers.
