The structure and morphology of gold nanoparticles produced in cationic gemini surfactant systems

Potential applications of gold nanoparticles (GNP) are strictly connected with their size and shape. The influence of different dicationic (gemini) surfactants, alkyloxymethylimidazolium derivatives derivatives, on the structure and morphology of GNP was studied. The synthesis of nanoparticles was performed in the presence of various gemini surfactants—dodecyloxymethylimidazolium nitrate (IMINO3C4C12), propionate (IMIPROPC4C12) and 3,3'-[1,9-(2,8-dioxanonane)]bis-(1-nonyloxymethylimidazolium) chloride (IMICloxyC7C9), used as stabilizers and templates for obtaining different size and shape of gold nanoparticles. The samples obtained were examined using transmission electron microscopy (TEM), small angle scattering of synchrotron radiation (SAXS), UV–vis spectroscopy and NMR PFG spectroscopy. For the obtained solutions of nanoparticles the plasmon resonance was observed at the wavelengths corresponding to the presence of gold nanoparticles of sizes ranging from 5–100 nm, with a significant shift towards higher wavelength for the samples prepared with addition of dicationic surfactants. TEM images evidence the presence of gold nanoparticles with tetrahedral and spherical morphology in solutions prepared with the surfactants IMIPROPC4C12, IMINO3C4C12, and those of spherical morphology, but strongly aggregated, in the solution with the cationic surfactant IMICloxyC7C9. - Highlights: • The shape and size of gold nanoparticles (GNP) depend on the concentration of gemini surfactants. • IMINO3C4C12 and IMIPROPC4C12 changed GNP morphology from spherical to tetrahedral. • Gold nanoparticles prepared in the presence of IMICloxyC7C9 were strongly aggregated