ABSTRACT
Nanotechnology is a multidisciplinary field that emerged in recent years due to the development of tools to "see", study and manipulate matter at atomic and molecular levels. Stilbene and some of its derivatives are organic molecules found in nature, which have chemical structures of interest in nano-fabrication of molecular machine building blocks (with prospective applications in nano-sensors, data storage and drug controlled release, among others). However, they have not been extensively explored as nanomaterials. This kind of systems is of interest in medicine, pharmacy and biotechnology.
This work presents the first results obtained by studying stilbene isomers: cis- and trans-stilbene, liquid and solid at room temperature, respectively, to explore their properties on polycrystalline substrates of gold (Au/mica) and graphite (HOPG).
We found that immobilization of trans-stilbene on a substrate can modify the crystallization process of the organic molecules, and the crystal morphology depends on the substrate. While trans-stilbene forms clusters that lead to pseudo-rhomboidal crystals on HOPG, dendritic structures with 90 º proyected branches are formed on equally prepared samples of Au/mica.
Additionally, we found at nanometer scale that cis-stilbene forms clusters on HOPG as well, similarly to trans-stilbene. A gradual increase in the amount of cis-stilbene enlarges the clusters until they coalesce in an amorphous phase. In contrast, the molecule-substrate interactions of cis-stilbene on Au/mica are weaker than on HOPG and do not form crystal nuclei centers or stable nanostructures. Instead, increasing cis-stilbene molecular concentration on Au/mica leads to a sort of liquid film.
Keywords:
cis-stilbene; trans-stilbene; HOPG; Au/mica; AFM
