A Generalized Ligand-Exchange Strategy Enabling Sequential Surface Functionalization of Colloidal Nanocrystals

The ability to engineer surface properties of nanocrystals (NCs) is important for various applications, as many of the physical and chemical properties of nanoscale materials are strongly affected by the surface chemistry. Here, we report a facile ligand-exchange approach, which enables sequential surface functionalization and phase transfer of colloidal NCs while preserving the NC size and shape. Nitrosonium tetrafluoroborate (NOBF4) is used to replace the original organic ligands attached to the NC surface, stabilizing the NCs in various polar, hydrophilic media such as N,N-dimethylformamide for years, with no observed aggregation or precipitation. This approach is applicable to various NCs (metal oxides,…