Controlling the properties of self-assembled monolayers by substrate curvature

Properties of self-assembled monolayers (SAMs) can be tailored by the curvature of the underlying surface. This is so because on a curved support the density of SAM headgroups is always smaller than that of the surface-attachment sites. This density difference increases with increasing curvature and is most pronounced for SAMs formed on nanoscopic particles. This Perspective describes systems in which nanoscale curvature causes pronounced changes in the pK(a) of acid-presenting SAMs or in the electrochemical potential of redox-active molecules (including supramolecular "switches") attached to nanoparticles. It is suggested that in nanoparticles having regions of different curvature these geometrical differences can translate into site-selective charging; such "patchy" particles could be used as building blocks of pH-sensitive assemblies.