Daniel Paley (Nuckolls Group)
3:00pm - 4:00pm
Bottom-up molecular synthesis is a route to chemically and crystallographically uniform polymers and solid-state materials. Through the use of molecular precursors, we gain atomic-level control of functionality and fine-tuning of the collective properties of materials. I will present two studies that demonstrate this approach.
Ring-opening alkyne metathesis polymerization is a possible approach to monodisperse conjugated polymers, but its applications have been limited by difficult syntheses and high air sensitivity of known organometallic ROAMP initiators. We designed a dimeric, air-stable molybdenum alkylidyne with a tris(phenolate) supporting ligand. The precatalyst is activated by addition of methanol and polymerizes cyclooctynes with excellent chemical selectivity and functional group tolerance.
The Nuckolls and Roy groups have introduced a new family of solid-state compounds synthesized from cobalt chalcogenide clusters Co6Q8(PR3)6 and fullerenes. The first examples of these materials crystallized in superatom lattices with the symmetry of simple inorganic solids CdI2 (P-3m1) and NaCl (Fm-3m). Further members of the family have displayed extraordinary diversity of structure, including a pseudo-trigonal array of fulleride dimers in [Co6Te8(PEt3)6]2[C140][C70]2 and a heterolayered van der Waals cocrystal [Co6Se8(PEt2phen)6][C60]5. In addition to these unusual crystal structures, I will present a method for assigning redox states from crystallographic data in Co6Q8 clusters.