Simple and environmentally friendly preparation and stabilization of gold nano- and microcrystals using N,N′,N″-tris(2-aminoethyl)phosphoric triamide

Gold nano- and microcrystals have been fabricated in environmentally benign conditions in the presence of aqueous N,N′,N″-tris(2-aminoethyl) phosphoric triamide that functions both as a reducing agent for gold ions and as a capping agent for the resulting gold crystals. The reaction temperature has been proved to be of pivotal factor in tuning the size and morphology of the gold crystals. Other parameters such as gold ion concentration, stirring condition and reaction time have also been investigated to figure out the self-assembled growth process of gold nanoparticles (AuNPs). The plausible mechanistic pathways of the crystal growth process for both nano- and microcrystals have been proposed. The colloidal solutions of different gold crystals show their own characteristic surface plasmon resonance properties according to the size from visible to near infrared region.