The 2 H NMR analyses give a general picture of segmental dynamics of ligands on pure-and mixedligand NCs (Figure ). In this picture, the chains of alkanoate ligands extend from the convex surface of NCs. The gradient in lateral packing density results in three characteristic dynamic modes: rigid, tgg rotation, and cone diffusion. As compared to those on pure-ligand NCs, the long ligands on mixedligand NCs exhibit greater flexibility because their outer segments experience much less lateral restriction.