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Surface Chemistry of Thiomalic Acid Adsorption on Planar Gold and Gold Nanoparticles.
MedLine Citation:
PMID:  24479895     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The self-assembly of thiomalic acid (TMA) on Au(111) and on preformed Au nanoparticles (AuNPs) protected by weak ligands has been studied by X-ray photoelectron spectroscopy (XPS) and electrochemical techniques. Results show that TMA is adsorbed on the Au(111) surface as thiolate species with a small amount of atomic sulfur (~10%), and a surface coverage lower to that found for alkanethiols due to steric factors. The amount of atomic sulfur markedly increases when the TMA is adsorbed on AuNPs by the ligand exchange method. We propose that the atomic sulfur is produced as a consequence of C-S bond cleavage, a process that is more favorable at defective sites of the AuNPs surface. The bond scission is also assisted by the presence of the electron-withdrawing carboxy moiety in alpha position relative to the C-S bond. Moreover, the high local concentration of positive charged species increases the stability of the negatively charged leaving group, leading to a higher amount of coadsorbed atomic sulfur. Our results demonstrate that the terminal functionalities of thiols are conditioning factors in the final structure and composition of the adlayers.
Authors:
Julio César Azcárate; María Alejandra Floridia Addato; Aldo A Rubert; Gastón Corthey; Germán Sebastían Kürten Moreno; Guillermo A Benitez; Eugenia Zelaya; Roberto C Salvarezza; Mariano Hernán Fonticelli
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-1-30
Journal Detail:
Title:  Langmuir : the ACS journal of surfaces and colloids     Volume:  -     ISSN:  1520-5827     ISO Abbreviation:  Langmuir     Publication Date:  2014 Jan 
Date Detail:
Created Date:  2014-1-31     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882736     Medline TA:  Langmuir     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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