Self-Assembled Monolayers of NH2‑Terminated Thiolates: Order, pKa, and Specific Adsorption

W. A. MARMISOLLE; D. A. CAPDEVILA; E. DE LA LLAVE; F. J. WILLIAMS; D. H. MURGIDA

LANGMUIR

AMER CHEMICAL SOC

Lugar: Washington; Año: 2013 vol. 29 p. 5351 - 5359

0743-7463

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 heteroge- neous electron transfer of positively charged macromolecules such as cytochrome c