Abstract: Colloidal semiconductor quantum dots (QDs) have been widely investigated due to their attractive properties such as size-tunable absorption and emission spectra, large molar extinction coefficients, and significant photostability. These properties make them promising candidates for optoelectronic, photocatalytic, and biomedical applications. Common synthetic procedures of QDs produce nanocrystals capped with long chain fatty acid derivatives which are stabilized in high boiling point solvents. Especially for bioimaging applications, the exchange of these native hydrophobic ligands with hydrophilic ligands should be performed, while preserving the smaller hydrodynamic radius. Coordination environment and thermodynamic parameters of the ligand exchanges should be carefully investigated to engineer improved ligand architectures to stabilize QDs in polar environments.

In this talk, I will describe the synthesis and characterization of highly photoluminescence CdSe/ZnS core/shell QDs and further dive into several types of small-molecule and polymer ligand exchanges that I have performed in order to bring QDs into polar solvents. Techniques such as inductively coupled plasma optical electron spectroscopy and NMR to quantify the ligand exchanges and isothermal calorimetry to find out the thermodynamic parameters of binding will be discussed.