Surface-Confined Amorphous Films from Metal-Coordinated Simple Phenolic Ligands

Coordination chemistry of natural polyphenols and transition metals allows rapid self-assembly of conformal coatings on diverse substrates. Herein, we report that this coordination-driven self-assembly process applies to simple phenolic molecules with monotopic or ditopic chelating sites (as opposed to macromolecular, multitopic polyphenols), leading to surface-confined amorphous films upon metal coordination. Films fabricated from gallic acid, pyrogallol, and pyrocatechol, which are the major monomeric building blocks of polyphenols, have been studied in detail. Pyrocatechol, with one vicinal diol group (i.e., bidentate), has been observed to be the limiting case for such assembly. This study expands the toolbox of available phenolic ligands for the formation of surface-confined amorphous films, which may find application in catalysis, energy, optoelectronics, and the biomedical sciences.