Nanocrystals as chemical building blocks

Nanoparticles have interesting analogies to molecules. Recent research has revealed that nanocrystals can align and fuse to larger single crystalline units (Oriented Attachment) or build self-assembled superstructures with mutual crystallographic order (Mesocrystals). These examples suggest that it should be possible to establish chemistry with nanocrystals as chemical building blocks. Nanocrystals are similar to molecules concerning active reaction sites and ability for directed interactions. Oriented attachment is analogous to chemical bond formation, while mesocrystal formation is analogous to non-covalent bonds in complexes between molecules. Key for the defined nanocrystal activation as chemical building unit is the selective adsorption/desorption of specially designed molecules on pre-defined crystal faces. Examples for this concept will be given for gold nanoparticles.
Alternatively, interaction of the nanocrystal surface adsorbed molecules can be induced, leading to mesocrystal formation. Examples will be given for magnetite mesocrystals and their analogies to classical crystals will be discussed. Also, first results on the formation of binary mesocrystals will be given, combining the properties of chemically different nanocrystals.

Bio: HELMUT CÖLFEN is full professor for physical chemistry at the university of Konstanz. His research interests are in the area of nucleation, classical and non-classical crystallization, Biomineralization, synthesis of functional polymers, directed self assembly of nanoparticles and fractionating methods of polymer and nanoparticle analysis. He has published more than 350 papers and was listed among the top 100 chemists 2000 – 2010 by Thomson Reuters.