Carboranethiol-Modified Gold Surfaces. A Study and Comparison of Modified Cluster and Flat Surfaces

Abstract

Four different carboranethiol derivatives were used to modify the surfaces of gold nanoparticles and flat gold films. The novel materials engendered from these modifications are extraordinarily stable species with surfaces that support self-assembled monolayers of 1-(HS)-1,2-C2B10H11, 1,2-(HS)2-1,2-C2B10H10, 1,12-(HS)2-1,12-C2B10H10, and 9,12-(HS)2-1,2-C2B10H10, respectively. Surprisingly, characterization of these materials revealed that a number of molecules of the carboranethiol derivatives are incorporated inside the nanoparticles. This structural feature was studied using a number of techniques, including X-ray photoelectron spectroscopy (XPS), UV-vis, and IR spectroscopies. Thermal desorption experiments show that carborane molecules detach and leave the nanoparticle surface mostly as 1,2-C2B10H10 isotopic clusters, leaving sulfur atoms bound to the gold surface. The surfaces of both the gold nanoparticles and the flat gold films are densely packed with carboranethiolate units. One carborane cluster molecule occupies an area of six to seven surface gold atoms of the nanoparticle and eight surface gold atoms of the flat film. XPS data showed that molecules of 1,12-(HS)2-1,12-C2B10H10 bind to the flat gold surface with only half of the thiol groups due to the steric demands of the icosahedral carborane skeleton. Electrochemical measurements indicate complete coverage of the modified gold surfaces with the carboranethiol molecules.

Size-controlled gold nanocolloids on polymer microsphere-stabilizer via interaction between functional groups and gold nanocolloids

“…Therefore, the steric effect of the microspheres did not play an active role in the stabilization of Au nanocolloids here. X-ray photoelectron spectroscopy (XPS) is an effective method to determine the interaction at the interface, especially for solid material, which has been extensively used to investigate the interaction between the stabilizer and Au nanocolloids [32][33][34]. To understand the nature of interaction between the functional groups of the polymer microspheres and Au nanocolloids, XPS for Au4f and the relative atoms interacting with Au were measured for the microsphere-stabilized Au nanocolloids and the blank samples as shown in Figs.…”

Catalytic properties of carboxylic acid functionalized-polymer microsphere-stabilized gold metallic colloids

“…3 and 4, respectively. XPS is an effective method for analyze the interaction at the interface, especially for solid material, which has been extensively used to investigate the interaction between the stabilizer and Au particles [33][34][35].…”

A borane laser

“…As chemical and physical behaviour is often a function of structure, then the boron hydrides have, with their unique polyhedral molecular geometries, large potential for novel properties. This is indeed the case, and in recent times boron hydrides-or boranes as these compounds are more commonly referred to-and their derivatives are proving promising candidates for application in medicinal fields 15 , microelectronics 16 , reversible capture of small molecules 17 , catalysis 18 , in the modification of surfaces 19 and as enhancers of the fluorescent properties of various luminescent organic polymers or fluorophores 20 .…”