Hydrophilic surfaces via the self-assembly of nitrile-terminated alkanethiols on gold

Abstract

A series of CN-terminated alkanethiols were synthesized and used to generate self-assembled monolayers (SAMs) on gold. The SAMs were characterized using ellipsometry, contact angle goniometry, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS). The SAMs were compared to those derived from a series of analogous CH₃-terminated alkanethiols. The CN-terminated SAMs exhibited lower film thicknesses than the CH₃-terminated SAMs, which was largely due to their greater tilt angle on the surface. Additionally, the CN-terminated SAMs form well-ordered films on flat gold surfaces with relative packing densities being indistinguishable from the CH₃-terminated SAMs. The CN-terminated SAMs exhibited a less hydrophobic character than the SAMs derived from CH₃-terminated adsorbates, which was attributed to the dipole moment of the terminal group as well as the lone pair of the nitrogen atom of the CN-terminal group.