Contrasting Ligand-Exchange Behavior of Wurtzite and Zinc-Blende Cadmium Telluride Nanoplatelets

The ligand-exchange chemistries of wurtzite (WZ) and zinc-blende (ZB) CdTe nanoplatelets are compared and contrasted. WZ CdTe nanoplatelets of composition (CdTe)[(n-octylamine)0.15(oleylamine)0.27] undergo reversible L-type to Z-type ligand exchange with Cd(oleate)2, Zn(oleate)2, CdCl2, and ZnCl2. However, the WZ CdTe nanoplatelets are unstable with anionic X-type ligation. In contrast, ZB CdTe nanoplatelets of composition (CdTe)3[Cd(carboxylate)2]0.74 (carboxylate is a mixture of oleate and propionate) undergo semireversible X-type to X′-type ligand exchange with CdCl2, CdBr2, and ZnCl2 but do not exhibit Z-type to L-type ligand exchange. The contrasting ligand-exchange behaviors of the WZ and ZB CdTe nanoplatelets are consistent with their contrasting facet structures. The WZ nanoplatelets express majority nonpolar facets and prefer neutral L- or Z-type ligation, whereas the ZB nanoplatelets express polar, cationic facets and prefer anionic X-type ligation.