title: 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.
authors.affiliation: Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic, 250 68 ReZ near Prague, Czech Republic. tbase@iic.cas.cz
authors.forename: Tomás
authors.initials: T
authors.lastname: Base
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Bastl
authors.forename: Zbynek
authors.initials: Z
authors.lastname: Plzák
authors.forename: Tomás
authors.initials: T
authors.lastname: Grygar
authors.forename: Jaromír
authors.initials: J
authors.lastname: Plesek
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Carr
authors.forename: Václav
authors.initials: V
authors.lastname: Malina
authors.forename: Jan
authors.initials: J
authors.lastname: Subrt
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Bohácek
authors.forename: Eva
authors.initials: E
authors.lastname: Vecerníková
authors.forename: Otomar
authors.initials: O
authors.lastname: Kríz
mesh_terms: D001896:Boron Compounds / Q000737:chemistry*; D004563:Electrochemistry; D006046:Gold / Q000737:chemistry*; D008567:Membranes, Artificial; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry; D010316:Particle Size; D012680:Sensitivity and Specificity; D013053:Spectrophotometry; D013055:Spectrophotometry, Infrared / Q000379:methods; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D017155:Wettability; D014965:X-Rays
chemical_list: D001896:Boron Compounds; D008567:Membranes, Artificial; D013438:Sulfhydryl Compounds; D006046:Gold