NSF Award
2400038
With the support of the Chemical Structure, Dynamics, and Mechanisms-B program in the Division of Chemistry, Professor Brueckner of the University of Connecticut is studying porphyrins and chlorins, members of the ‘pigments of life’ involved in many metabolic processes and light harvesting. These investigations aim at the understanding of their fundamental properties that allowed them to become so important for life. The new compounds prepared also possess properties that suggest their utilization in non-natural applications. For instance, some modified materials are more flexible than their natural counterparts and change their color when deformed. They are therefore suitable to generate materials that can make physical stress visible; this is important for many engineering disciplines. The conversion of carbon dioxide to valuable products is one of the pressing problems of our time. The study of some metal complexes of the modified porphyrins in these conversions expands our understanding how best to do this. These studies will offer a multidisciplinary and collaborative training ground for students in areas ranging from organic and inorganic synthesis to physical organic chemistry, with exposure to photophysics and a number of biomedical and engineering applications. This will prepare students well for future careers in industry, academia, or public service.<br/><br/>The proposed study focuses on the formal replacement of a pyrrolic building block in porphyrins by stepwise synthetic manipulation of porphyrins. This generates a family of so-called pyrrole-modified porphyrins (PMPs) incorporating one or more non-pyrrolic building blocks. The often dramatic conformational and electronic effects – especially when the building blocks are larger than the five-membered pyrrole they replace – are being studied. One focus in these studies is the impact the replacement has on the aromaticity of the PMPs. An appreciation for the chemical transformations taking place within the constraints of a porphyrinic macrocycle assists in the rational design of novel porphyrinoids of utility. The evaluation of select conformationally flexible PMPs in mechanochromic polymers delineates the scopes and limits of utilizing PMPs in the realization of smart materials. Some PMPs suggest their capacity to act as electron sinks. This will be probed by the use of their Co(II) complexes in electro-catalytic multi-electron reductions of carbon dioxide. Success in these endeavors has the potential to provide important long term lessons in porphyrin tuning to build in useful function.<br/><br/>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.
