Self-assembling of 2,3-phenyl/thienyl-substituted acrylic acids over polycrystalline gold

Abstract

Self-assembling layers were formed from sulfur-containing cinnamic acid analogues over polycrystalline Au surface. The horizontal organising forces were strong O–H⋯O and weaker C–H⋯S hydrogen bonds (the former interaction kept together the acid dimers serving as the fundamental unit, while the latter was crucial in the construction of the 2D layers), while the vertical organisation forces were provided by Au–S covalent bonds. Measurements by atomic force, scanning electron, infrared and Raman microscopies attested that the dimers were situated in a nearly perpendicular fashion to the Au surface providing a ∼30–40nm thick organic “carpet” and out of this layer occasionally, peaks with height of ∼100–120nm grew out. The outgrowth of these surface structures were most probably governed by the defects of the polycrystalline metal surface.