Self-assembled molecular network formed by controlling molecular deposition of organic compounds

Abstract

Self-assembled molecular networks enable spatial and temporal control of surface chemical functionalities. However, in most cases, the deposition process is unsuitable to the growth of multilayers. In this study, we attempted the consecutive deposition of a two-dimensional supramolecular array on another to fabricate an organic layer (OL) and realize the growth mechanism on underlying inorganic layer of distinct ordered layers, each of which is stabilized by in-plane non-covalent bonds. An OL was formed by depositing pyromellitic acid (PMA) through ultrahigh-vacuum physical vapor deposition on a metal-oxide and metal-aluminate system tailored by plasma electrolytic oxidation, and the unique interface between the organic and inorganic layers was characterized by field-emission transmission electron microscopy under ambient conditions. The adsorption behavior of pyromellitic acid (PMA) on the inorganic surface was investigated by computational calculations. The adsorption of PMA over an inorganic surface was more favorable than the adsorption between PMA molecules themselves.