Thiolate Ligands for Synthesis of Water-Soluble Gold Clusters

Abstract

Water-soluble monolayer-protected gold clusters (MPCs) have been an object of investigation by many research groups since their first syntheses were reported in 1998 and 1999. The basic requirements for a ligand to form a monolayer protecting a gold cluster were established some time ago for alkanethiolate MPCs, but there has been no such information published for water-soluble MPCs. We identify 6 new ligands capable of forming water-soluble MPCs, as well as 22 water-soluble ligands that fail to form MPCs. Our findings contribute not only to the definition of the requirements for MPC formation but also to the variety of MPCs available for applications in chemistry and biology.

Chemical Analysis of the Superatom Model for Sulfur-Stabilized Gold Nanoparticles

“…[1][2][3] Key structural information for gold nanoparticles was recently obtained from the X-ray diffraction results of Jadzinsky et al with 1.1 Å resolution. 4 They found that adatom-bound RS-Au-SR-type "staple" bonding motifs cover the surface of an Au 79 core in the stable Au 102 (SR) 44 cluster; the stabilizing ligand SR used was S-C 6 H 4 -COOH derived from p-mercaptobenzoic acid (p-MBA), HSR.…”

“…These units are oriented with their nearly collinear S-Au-S atoms almost parallel to the core surface and their organic groups pointing outwards. Figure 1 shows an analogous structure in which this complex adsorbate is replaced with the methanethiyl (MT) radical SR = SCH 3 , maintaining the original RS-Au-RS head-group torsional angles; this modification allows the key structural features to be more easily visualized. The Au 79 gold core is also shown in Figure 1 and has pseudo D 5h…”

Chirally modified gold nanoparticles: nanostructured chiral ligands for catalysis

“…This feature is demonstrated by using the novel particle 2 in a well-known catalytic reaction. Its selectivity is superior to its polymer-supported analogue and only somewhat poorer than that of the soluble benzyl analogue (6). A catalyst designed like 2 is, however, being pursued for applications in e.g.…”

“…The synthetic value lay in the possibility to differentiate the size of the gold core by precipitation. New applications have been made using the Brust-Schiffrin -protocol, including water-soluble particles 6 and other clusters, coated with simply functionalized small molecules (monolayerprotected). 7 Self-assembly of the layers on gold surface has also been reported, 8 as well as syntheses giving the opportunity to adjust the core size.…”

“…To our knowledge, particles of this size have never been experimentally synthesized. Both water soluble, 6 and achiral catalytially active 22,23 gold nanoparticles with a diameter below 2 nm have, however, been previously reported. The TEM images also show that the chirally coated particles are much smaller and show narrower size distribution than the hexanethiolate coated particles (Figures 1 and 2).…”