International Collaboration in Chemistry: Exploring and Controlling the Reactivity of Endohedral Fullerenes

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TECHNICAL SUMMARY:With support from the International Collaboration in Chemistry (ICC) Program and the Macromolecular, Supramolecular, and Nanochemistry Program of the NSF, Professor Echegoyen from the University of Texas-El Paso and Professors Martin, Poblet and Torres from Spain will synthesize, isolate, and characterize a series of new fullerene derivatives with highly unusual electronic properties. Some of the new derivatives will possess one or more attached ferrocene or ruthenocene groups to five-membered rings on the surface of endohedral fullerenes, to yield the first endohedral buckymetallocenes ever reported. Electronic coupling between the exo- and endohedral metal species will be measured and analyzed. The properties of these new compounds will be fully characterized using a wide variety of techniques, especially electrochemistry, looking for endo-exo interactions and their relationship to the overall properties. In a second project, a new series of Covalent Organic Frameworks (COFs) based on newly designed porphyrins and phthalocyanine linkers will be prepared, in an effort to obtain COFs with relatively large pore sizes. The ability to incorporate fullerenes inside these COF pores will be probed with a variety of techniques to try to assess if Donor-Acceptor (D-A) interactions exist and how strong they are. NON-TECHNICAL SUMMARY:Fullerenes, also called 'Buckyballs' are all-carbon compounds with unique and somewhat unusual electronic properties that make them useful in many applications, for example in solar cells. They are closed carbon structures (the one possessing only 60 carbons is identical to a soccer ball) and are capable of undergoing chemical reactions on their surfaces. Fullerenes that encapsulate other species inside, such as clusters of other atoms, are called endohedral fullerenes, and these have very interesting and unique electronic properties. Many reactions have been used to functionalize the surfaces of fullerenes, both empty as well as endohedral, but some unique ones will be explored in the present work, especially on the endohedral compounds. The resulting compounds will be characterized and their properties measured, specifically looking at potential applications in solar photovoltaics. Besides the immediate educational experience and mentoring provided to the undergraduate and graduate students involved in this project, the most profound broader impact of this project derives from the commitment of the US Principle Investigator (PI) to recruit and educate underrepresented minorities in his laboratories. The PI actively recruits Puerto Rican and other Hispanic and minority students to his labs as evidenced by the fact that 14 of his 22 PhD graduates have been Hispanic. In addition to actively mentoring underrepresented minority students (Hispanics primarily), this project involves very strong international collaborations with three different research groups in Spain, two being synthetically oriented and one theoretical. The PI has a long and fruitful history in both of these broader impact areas and these are expected to continue under the present grant.