Ligand Exchange Reactions Yield Subnanometer, Thiol-Stabilized Gold Particles with Defined Optical Transitions

Abstract

A convenient preparation is reported for a series of functionalized, thiol-stabilized gold particles with subnanometer core diameters (d CORE ) 0.8 ( 0.2 nm). The preparation produces previously inaccessible materials through ligand exchange reactions of a phosphine-stabilized precursor, Au 11 (PPh 3 ) 8 Cl 3 , with ω-functionalized alkanethiols. Convenient access to these new materials is a prerequisite to the detailed study of the electronic and optical properties of subnanometer particles and the investigation of the utility of these building blocks in nanoscale devices. Preliminary investigations of the optical properties of these new materials by UV-vis spectroscopy revealed that the particles have defined optical transitions. These results confirm the presence of discrete energy levels in the electronic structure of these materials that might be expected due to quantum size effects. Initial studies also suggest that the optical properties depend on the nature of the stabilizing ligand shell. The ligand exchange method described is applicable for a diverse family of alkanethiols to produce both organic-and water-soluble particles that show increased stability over the phosphine-stabilized precursor. Extensive characterization indicates that the thiol-stabilized exchange products have well-defined core sizes and dispersities.

The Effect of Ligand Denticity in Size‐Selective Synthesis of Calix[n]arene‐Stabilized Gold Nanoparticles: A Multitechnique Approach

“…Despite the documented potentiality of these systems, [8] the development of reliable direct synthetic protocols for the synthesis of stable and lipophilic AuNPs characterized both by very small core diameter and potential recognition properties of the organic shell still remains a challenging task. [9] The combination of these features could indeed lead to the manufacture of nanoscale devices with potential applications as sensors, switches, and new materials that have tunable properties.…”

Exclusive synthesis of Au11(PPh3)8Br3 against the Cl Analogue and the Electronic Interaction between Cluster Metal Core and Surface Ligands

“…The structure of Au 11 was revealed to be an incomplete icosahedral skeleton with an approximately C 3v symmetry by single crystal X-ray diffraction by various research groups. [1,2,10,12] Recently, it was found that the number of phosphine can be eight, too, when triphenyl phosphine was employed to protect the Au 11 core, [9,11] and the formula was determined to be Au 11 -A C H T U N G T R E N N U N G (PPh 3 ) 8 Cl 3 by electrospray ionization mass spectrometry (ESI), thermogravimetric analysis (TGA), elemental analysis, etc. In both cases (i.e., Au 11 …”

The fabrication and surface functionalization of porous metal frameworks – a review

“…Therefore, general pathways for pure metal functionalization may lead to unstable bonds that can be impaired through the input of thermal, chemical or electrical energy 221,222 . Pure metal nanoparticles have been successfully functionalized with thiols 204,223,224 , di-sulfides 200 , amines 223,[225][226][227] , nitriles, carboxylic acids and phosphines 225,226,228 . Selected examples will be presented in the following sections.…”

“…This procedure is interesting for the functionalization of nanostructured surfaces where the organic function to be introduced is not compatible with the synthesis conditions of the pure metal surface 239 . The stability of thiols is limited and thiols were shown to desorb during aging in biological media 224,240 , which was directly related to the electronic structure of the metal particle core 228 .…”