INVESTIGADORES
RUBERT Aldo Alberto
artículos
Título:
Thiol with an Unusual Adsorption-Desorption Behavior: 6-Mercaptopurine on Au(111)
Autor/es:
EVANGELINA PENSA; PILAR CARRO; ALDO A. RUBERT; GUILLERMO A. BENITEZ; CAROLINA VERICAT; ROBERTO C. SALVAREZZA
Revista:
LANGMUIR
Editorial:
AMER CHEMICAL SOC
Referencias:
Año: 2010 vol. 26 p. 17068 - 17074
ISSN:
0743-7463
Resumen:
A multitechnique study of 6-mercaptopurine (6MP) adsorption on Au(111)
is presented. The molecule adsorbs on Au(111), originating short-range
ordered domains and irregular nanosized aggregates with a total surface
coverage by chemisorbed species smaller than those found for alkanethiol
SAMs, as derived from scanning tunneling microscopy (STM) and
electrochemical results. X-ray photoelectron spectroscopy (XPS) results
show the presence of a thiolate bond, whereas density functional theory
(DFT) data indicate strong chemisorption via a S−Au bond and additional
binding to the surface via a N−Au bond. From DFT data, the positive
charge on the Au topmost surface atoms is markedly smaller than that
found for Au atoms in alkanethiolate SAMs. The adsorption of 6MP
originates Au atom removal from step edges but no vacancy island
formation at (111) terraces. The small coverage of Au islands after 6MP
desorption strongly suggests the presence of only a small population of
Au adatom−thiolate complexes. We propose that the absence of the Au−S
interface reconstruction results from the lack of significant repulsive
forces acting at the Au surface atoms.