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Updated: May 12, 2026

Investigating Single Molecule Adhesion by Atomic Force Spectroscopy
Published on: February 27, 2015
Self-assembled monolayers of NH2-terminated thiolates: order, pKa, and specific adsorption
Waldemar A Marmisollé1, Daiana A Capdevila, Ezequiel de la Llave
1Departamento de Química Inorgánica, Analítica y Química Física and INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET, Ciudad Universitaria, pab. 2, piso 3, C1428EHA-Buenos Aires, Argentina.
Abstract:
Self-assembled monolayers (SAMs) of amino-terminated alkanethiols on Au were characterized by a combination of electrochemical (LSV, CV, and EIS) and spectroscopic (XPS and SER) techniques. Clear correlations were obtained between the apparent surface pKa values determined by impedimetric titrations and order parameters such as the content of trans conformers in the SAMs. These results contrast with previous studies that exhibit dispersions of up to 6 pH units in the reported pKa values. In addition, we determined that inorganic and organic phosphate species bind specifically to these SAMs mediating adsorption and heterogeneous electron transfer of positively charged macromolecules such as cytochrome c.
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