Self-assembly mechanism of thiol, dithiol, dithiocarboxylic acid, disulfide and diselenide on gold: an electrochemical impedance study.
Phys Chem Chem Phys
; 15(39): 16648-56, 2013 Oct 21.
Article
em En
| MEDLINE
| ID: mdl-23970119
ABSTRACT
The self-assembly mechanism of normal aliphatic thiol (RSH), disulfide (RSSR), diselenide (RSeSeR), dithiol (R(SH)2) and dithiocarboxylic acid (RS2H) onto a gold surface was studied in real time by electrochemical impedance spectroscopy (EIS). The different stages of adsorption could be clearly followed from the interfacial capacitance variation. An initial very fast adsorption, varying from a few seconds to several minutes depending on concentration, is the major adsorption step. This fast step is followed by long-term additional adsorption and self-assembled monolayer (SAM) consolidation. However, an intermediate step, probably due to transformation from the initial physisorbed state to the self-assembled state, could be identified with RSH and R(SH)2. An intermediate rearrangement of RS2H molecules after their initial diffusion controlled Langmuir (DCL) adsorption through the thiol functional group was also recognized. Initial adsorption of RSH and R(SH)2 followed either purely diffusion controlled or DCL kinetics for a very short time. Their continuing fast adsorption followed DCL kinetics. The fast adsorption step of RSSR and RSeSeR also followed the same mechanism. The findings made with EIS on the SAM organization were analyzed by polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS). The R(SH)2 based SAMs had comparatively poor organization.
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1
Coleções:
01-internacional
Base de dados:
MEDLINE
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Phys Chem Chem Phys
Assunto da revista:
BIOFISICA
/
QUIMICA
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Bélgica