Seminar Abstract:

Long chain ligands have long been used to control size and shape of nanocrystals by binding to growing surfaces, but we have discovered rich molecular chemistries with the precursors that completely change the fate of the reaction.  To discover the fundamental rules behind phase control, it is important therefore to identify reactions that can isolate the effects of reaction kinetics from changing mechanistic routes. Substituted thioureas were reacted with iron, cobalt and nickel and copper salts. By mapping out the effects of precursor reactivity and temperature on the phase of the sulfides, hypotheses can be developed about the predictable paths that occur between phases based on their anion stacking and hole filling patterns. We discovered that the synthetic behavior of the iron, cobalt and nickel sulfides can mostly be predicted by the anion stacking of hcp or ccp. Based on these maps, we developed hypothesis driven syntheses to pyrrhotite (Fe_1-xS), mackinawite (Fe_1+xS), smythite (Fe_3+xS₄), greigite (Fe₃S₄), marcasite (FeS₂), pyrite (FeS₂), jaipurite (CoS), cobalt pentlandite (Co₈S₉), linnaeite (Co₃S₄), cattierite (CoS₂), a- NiS, millerite (NiS), godlevskite (Ni₉S₈), heazlewoodite (Ni₃S₂), polydymite (Ni₃S₄), vaesite (NiS₂).

Speaker Bio:

Janet Macdonald is an Associate Professor of Chemistry at Vanderbilt University, where she has been since 2011. Before that time, she did her graduate work at the University of Alberta under the supervision of Jon Veinot and a post-doctoral fellowship with Uri Banin at the Hebrew University of Jerusalem. Her group primarily focuses on how crystalline phase is determined in colloidal nanocrystal synthesis. Her group regularly collaborates with physicists and physical chemists to examines fundamental charge transfer processes from quantum dots, and plasmon-plasmon coupled harmonic light generation using combinations of metal and plasmonic semiconducting nanoparticles. Dr. Macdonald is an Associate Editor for Nanoscale and Nanoscale Advances.