Pyrrole-modified Porphyrins - Chromophores of Basic and Applied Interests

University Of Connecticut, Storrs CT

Investigators

Abstract

The Chemical Synthesis Program of the Chemistry Division supports the project by Professor Brueckner, a faculty member in the Department of Chemistry at the University of Connecticut. Blood is red and grass is green because of a particular class of compounds - so called porphyrins, that fulfill diverse roles throughout the living world. In addition to these natural roles, these highly colored compounds can potentially be used for a variety of "non-natural" applications that range from their use as contrast agents to improve the imaging of biological tissue for better disease detection to their use for the electrocatalytic reduction of carbon dioxide and in chemosensing efforts. With this in mind, Professor Brueckner is developing strategies to convert naturally occurring porphyrins to derivatives that possess properties the original compounds do not have. This allows them to be optimized for new applications. In addition, the derivatives being synthesized are well-suited for answering fundamental questions about the properties of the porphyrins and how those properties can be systematically altered by changes in structure. The project teaches graduate and undergraduate students in the techniques and methodologies that are used in the pharmaceutical and other industries. In this way, students are prepared to enter the workplace. Professor Brueckner's has traditionally been active in chemical education and in attracting students underrepresented in science to this most colorful research work. The multidisciplinary and very visual nature of the research make it ideal for outreach activities. The main objective of this proposal is the development of strategies to convert porphyrins into pyrrole-modified porphyrins (PMPs). PMPs are macrocycles derived from porphyrins by formally replacing at least one pyrrolic building block with a different heterocycle. Starting from synthetic porphyrins, a relatively little explored strategy will be pursued: activation of the beta-position of porphyrins, followed by ring cleavage and subsequent ring-fusion. Focus in this study is the generation of PMPs containing multiple modified pyrroles, medium-size rings, or multiple annulated ring systems. The guiding hypothesis is that these modifications result in altered electronic properties when compared to their parent compounds. The suitability of the PMPs in several biological (i.e., contrast agents in photoacoustic tissue imaging) and technical (i.e. electrocatalytic reduction of CO2, chemosensing) applications will be evaluated. The proposed work relies on collaborations with intramural and extramural (international) specialty groups in a number of biological, physical sciences and engineering disciplines. The program offers a multidisciplinary and collaborative training ground for graduate students in diverse areas ranging from organic and inorganic synthesis, physical organic chemistry, photophysics, to a number of biomedical and engineering applications. This prepares them for future careers in industry or academia. The proposal also includes year-round undergraduate research projects, and it will be part of the departmental REU program. The multidisciplinary porphyrin-related research activities are ideal for dissemination in non-technical journals and make colorful subjects of outreach activities. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.