Co2+-Doping of Magic-Sized CdSe Clusters: Structural Insights via Ligand Field Transitions

Magic-sized clusters represent materials with unique properties at the border between molecules and solids and provide important insights into the nanocrystal formation process. However, synthesis, doping, and especially structural characterization become more and more challenging with decreasing cluster size. Herein, we report the successful introduction of Co 2+ ions into extremely small-sized CdSe clusters with the intention of using internal ligand field transitions to obtain structural insights. Despite the huge mismatch between the radii of Cd 2+ and Co 2+ ions (>21%), CdSe clusters can be effectively synthesized with a high Co 2+ doping concentration of ∼10%. Optical spectroscopy and mass spectrometry suggest that one or two Co 2+ ions are substitutionally embedded into (CdSe) 13 clusters, which is known as one of the smallest CdSe clusters. Using magnetic circular dichroism spect…