The manipulation of ligands on nanocrystal (NC) surfaces is crucial in solution processing these materials into optoelectronic devices and fluorescent labels for biological imaging. With a fluorescence resonance energy transfer (FRET) based approach, we study the relative dispersion of freshly introduced ligands on the surface of NCs. In our system, a green and a red dye functionalized with NC binding groups were chosen as donor and acceptor respectively. FRET between these ligands indicate they are bound on CdS NC within the F�rster distance of 25 �, despite the fact that only an average of three new ligands are covalently attached to the NC surface. This may be an indication of cooperative binding, where the first binding event modifies the structure on the surface of the NC, thus leading to a change in binding constant for the second ligand. Cooperative binding is usually observed in biological systems, and haven't been reported in NC for organic ligands, especially at the low concentrations in our experiment.

Localizing newly introduced ligands on the surface of CdS nanocrystals

248th National Meeting (2014)

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