When Nanoparticle Size and Molecular Geometry Matter: Analyzing the Degree of Surface Functionalization of Gold Nanoparticles with Sulfur Heterocyclic Compounds

EDUARDO A. CORONADO

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2012 vol. 116 p. 6520 - 6520

1932-7447

he degree of surface functionalization of colloidal dispersions of Au nanoparticles (AuNPs) by sulfur heterocyclic compounds is determined using localized surface plasmon resonance spectroscopy (LSPRS), morphological characterization, and electrodynamic modeling. We demonstrate that AuNP surface coverage is the result of the interplay between the molecular geometry of ligands and the Au nanoparticle diameter. For the same ligand, it is found that the surface density of molecules (σ) is almost constant or slightly decreases as the Au nanoparticle diameter increases, while for the same NP size the degree of surface coverage increases as the length of the molecule increases. The chemical interaction between the ligand molecules and the AuNP surface is demonstrated using surface enhanced Raman scattering (SERS) and 1H NMR. For the same average AuNP size, the full width at half maximum (fwhm) of the LSPR is significantly greater for derivatized AuNPs, a feature that shows the importan