There has been an increased emphasis on understanding nanocrystal surface chemistry and the way that these surfaces interact with diverse solvent environments for broadening applications. To control the surface chemistry of nanocrystals, a deeper understanding of the mechanism of ligand binding and the conditions that control the rate of this process are necessary. In this study, native ligands on CdSe quantum dots were substituted for shorter ligands using a series of bifunctional molecules with consistent thiol anchoring groups and changing secondary functional groups. As new ligands were added to the as-synthesized nanocrystal solutions, nanocrystal band-edge fluorescence was analyzed for evidence of quenching, which is characteristic of thiol ligand binding. The ligand exchange was more quantitatively measured by using <sup>1</sup>H NMR. The <sup>1</sup>H NMR peaks of the free ligand and the nanocrystal-bound ligand were monitored and used to calculate equilibrium constants. Further, the importance of the ligand deprotonation step in this mechanism was clarified by varying the pH of the ligand solutions before substitution. These results were used to gain insight into the ligand binding mechanisms and to understand how the strength of binding is influenced by ligand functionality.

Ligand substitution on colloidal quantum dots: Mechanistic study

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.