title: Assembly of dithiocarbamate-anchored monolayers on gold surfaces in aqueous solutions.
abstract: Dithiocarbamates (DTCs) can be formed by the in situ condensation of polar alkylamines with CS 2, and assembled into dithiocarbamate-anchored monolayers (DAMs) on Au substrates in aqueous solutions. Primary and secondary amines can both be used to prepare DTCs, but have significant differences in their reactivities and product stabilities. Ultraviolet absorption spectroscopy provides a convenient method for monitoring in situ DTC formation as well as the formation of potential byproducts. The kinetics of DAM assembly on Au substrates as measured by second harmonic generation (SHG) indicated first-order rate processes and saturation coverages similar to those of alkanethiols on Au. However, the rate of adsorption did not change with DTC concentration in a manner expected of Langmuir kinetics, and is attributed to the competitive adsorption of alkylammonium counterions to the freshly oxidized Au substrate. These analyses establish a practical range of conditions for preparing DAMs from polar amines using in situ DTC formation.
authors.affiliation: Department of Chemistry and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Heng
authors.initials: H
authors.lastname: Zhu
authors.forename: Donna M
authors.initials: DM
authors.lastname: Coleman
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Dehen
authors.forename: Iris M
authors.initials: IM
authors.lastname: Geisler
authors.forename: Dmitry
authors.initials: D
authors.lastname: Zemlyanov
authors.forename: Jean
authors.initials: J
authors.lastname: Chmielewski
authors.forename: Garth J
authors.initials: GJ
authors.lastname: Simpson
authors.forename: Alexander
authors.initials: A
authors.lastname: Wei
mesh_terms: D000327:Adsorption; D005028:Ethylenebis(dithiocarbamates) / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D007201:Indicator Dilution Techniques; D007700:Kinetics; D015394:Molecular Structure; D012996:Solutions; D013053:Spectrophotometry; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013499:Surface Properties
chemical_list: D005028:Ethylenebis(dithiocarbamates); D012996:Solutions; D013438:Sulfhydryl Compounds; D006046:Gold