Affinity of Ligands Co-Ordinated on Gold Nanoparticles

Structural information at an assembled molecule/ solid interface has been limited, due in part to the obscure NMR signals for the atoms co-ordinated to the solid surface. Here, we report an effective detection of the surface composition of the ligands on gold nanoparticles (AuNPs) by 1H solid-state NMR under fast magic angle spinning. An investigation of the confinement effect of the ligand shell was successfully performed by multiple pulse dipolar filter NMR. We demonstrate that the affinity of surface species on AuNPs is affected not only by interfacial chemical bonding but also by physical confinement, leading to a new fundamental insight into the structure-property correlation for major interfacial behaviors, such as ligand exchange reaction and curvature effect on properties. The concept of physical confinement and the characterization method developed in this work is probably applicable to all ligand/nanoparticle interfaces and thus can provide a clue to the design and execution of the manipulating strategy for nanocomposites.