Surface characterization of thiol ligands on CdTe quantum dots: analysis by 1H NMR and DOSY

Proton nuclear magnetic resonance (1H-NMR) and diffusion-ordered spectroscopy (DOSY) were successfully used in the characterization of synthesized thiol-capped quantum dots (CdTe QDs), revealing that these fast and low-cost methods provide valuable information about the chemical ligand–core linkage nature and concentrations of ligands bound to CdTe QDs. A comparative study of XRD, DLS, and UV-vis techniques versus combined 1H-NMR/DOSY methods disclosed also that the latter methods are suitable for the complete description of thiol-capped CdTe QDs, evaluating their diffusion coefficient (e.g., hydrodynamic diameter), effective size, and particle size distribution. The results obtained indicate that the tested NMR spectroscopy procedure is a valuable toolbox for nanoparticle complementary characterization and could be applied to hybrid nanomaterials having organic molecules like capping agents or artificial encapsulation systems.