Experimental and vdW-DFT Study of the Structure, Properties and Stability of Isonicotinic Acid Self-Assembled Monolayer on Gold

MARÍ LAURA PARA; OMAR E. LINAREZ PÉREZ; MARIANA ISABEL ROJAS; MANUEL LÓPEZ TEIJELO

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2016

1932-7447

Self-assembling of derivatized aromatic moleculeson metals is of interest in the generation of modifiedsurfaces with ionizable groups in order to generate chargedsurfaces for constructing more complex nanostructuredinterfaces. In the present contribution we explore the structure,properties, and stability of isonicotinic acid (INA) adsorbed ongold surfaces employing electrochemical and spectroscopicmethods as well as DFT calculations at the level of van derWaals interactions (vdW-DFT). Electrochemical results showchanges in the kinetics of redox probes due to the selfassembledmonolayers (SAMS) formation on the gold surface.Furthermore, SERS experiments indicate that INA speciesadsorb on gold perpendicularly to the surface through the deprotonated carboxylate group. In addition, due to the ionizablegroups involved in the molecular anchorage, some instability of the SAMS of INA is obtained by pH modification of the chemicalenvironment. On the other hand, theoretical calculations indicate that a strong interaction of the carboxylate group to the goldsurface at the bridge sites takes place, and the adsorbed species have sufficient mobility at room temperature. The effect of thecoverage and the stability of the SAMS are also reported.