Formation of gold colloids using thioether derivatives as stabilizing ligands

Thioethers were used as adsorbates for preparing gold nanoparticles. Differ ent thioether derivatives having from 1 to 4 thioether functionalities were synthesized. Colloids were prepared in a two-phase system, and characteriz ed by H-1 NMR and transmission electron microscopy (TEM). The stability of colloids protected by thioethers increases with the number of ligands per m olecule. Monothioethers need longer chain lengths or costabilization by (oc t)(4)NBr in order to give stable, redispersible gold colloids. Gold colloid s stabilized by the bis(thioether) 5 could not be redispersed after precipi tation. Colloids stabilized by the tris(thioether) 6 were only formed at el evated temperature (60 degreesC) indicating the need of chain reorientation for attaining stable colloids. Tris(thioether) 7 gave stable colloids at r oom temperature, which could be redispersed even after precipitation. Tetra kis(thioether) 8 gave the smallest particle size and narrowest size distrib ution.