The synthesis and coordination chemistry of colloidal semiconductor quantum dots

I will describe our studies of nanocrystal nucleation and growth and surface coordination chemistry. First, I will present a library of derivatized thiourea and selenourea precursors whose wide range of reactivity adjusts the metal chalcogenide formation kinetics. Using this library we observe a well-defined relationship between solute supply and the concentration of nanocrystals allowing a desired nanocrystal size to be obtained in quantitative yield. Second, I will describe the important relationship between nanocrystal coordination chemistry and electronic structure. Using liquid NMR spectroscopy we have discovered a novel ligand exchange mechanism where the surface layer of excess metal cations on metal chalcogenide nanocrystals is displaced in the presence of neutral donor ligands. The importance of this behavior to luminescence quantum yield and nanocrystal synthesis will be discussed.