Abstract

The surface layer of organic ligands on nanoparticles plays a crucial role to stabilize the core structures, to control the shapes and morphology, and to modulate the surface chemistry. The functionalities of organic ligands rely not only on their coordination bonds, but also on the non-coordinating hydrocarbon tails. However, the interaction of tails involves weak intermolecular forces which are largely intractable on the spectra of common characterization techniques. Here, we present a solid-state nuclear magnetic resonance (SSNMR) measurement and modeling strategy to quantify the “dynamic volume” of chain segments. The dynamic volume depicts the accessible space of a chain segment under the confinement of neighboring molecules, and is inversely proportional to the intermolecular dispersive interaction energy. We show that the calculated ligand-ligand interaction energy determines the solution dispersity and melting transitions of nanoparticles. This dynamic volume concept can be extended beyond experimental measurements and offer semi-empirical predictions of the interaction energies of organic ligands.