With support from the Macromolecular, Supramolecular, and Nanochemistry Program of the NSF these researchers will synthesize, isolate, and characterize a series of new fullerene derivatives that will be used in the construction of new supramolecular architectures. The new derivatives will be regioisomerically pure compounds derived from C60 with bis- and tetra-functionalities arranged so that they can form 2D and 3D architectures via spontaneous assembly with specific and carefully selected metal ions. Architectures ranging from simple triangles and squares to 3D cubes and even more complex ones will be prepared, each containing fullerenes as intrinsic linker components. Such structures have never been reported before, especially containing fullerenes as linker units. The properties of these supramolecular compounds will be fully characterized. In a second project, other fullerene compounds will be synthesized and characterized for the first time using arc discharge techniques, mainly endohedral fullerene systems consisting of different carbon cage sizes containing a variety of atom clusters inside. While we have worked and will continue to work with trimetallic nitride endohedral systems (TMNs) this application focuses particular interest in a relatively new family of endohedrals discovered during the previous grant period, the dimetallic sulfides DMSs), M2S@C2n (M=Sc, and 40 NON-TECHNICAL SUMMARY: Fullerenes, also called "Buckyballs" are all-carbon compounds with unique and somewhat unusual electronic properties that make them useful in applications such as photovoltaics. They are closed carbon structures (the one with 60 carbons is identical to a soccer ball) capable of undergoing chemical reactions on their surfaces. One of the problems that will be addressed in this work is how to control the exact positions of the chemical groups that will be added to the surface, since lack of control leads to the preparation of too many different compounds (isomers). Limiting the number of isomers to obtain only the desired compounds is part of the aim of this work. Once prepared, the new derivative compounds will be incorporated into more complicated structures using mainly metal ions to induce their formation spontaneously. These structures will be characterized and their properties measured. In addition to empty carbon cage fullerenes, new endohedral derivatives will be prepared which contain metallic and non-metallic atoms encapsulated in the cages, like molecular maracas. The purpose is to vary and control the electronic properties for potential photovoltaic applications in the future. Besides the immediate educational experience and mentoring provided to the undergraduate, graduate and postdoctoral associates involved in this project, the most profound broader impact of this project derives from the commitment of the 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), the PI is heavily involved in international collaborations, mainly with Spain and Germany and publishes extensively with them, as evident from his biographical sketch. 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.
