Crystal engineering of 2,7-bis(10-alkoxy)-9-fluorenone at homologous series of fatty acids/graphite interface

Abstract

Fluorenone derivatives are excellent organic light-emitting materials, which have been received broad focus. By the Scanning tunneling microscopy we designed and synthesized a series of fluorenone derivatives and fabricated and controlled molecular nanostructures on the graphite surface. The assembly of symmetric 2,7-bis(10-alkoxy) -9-fluorenone dissolved in homologous acids was observed. Solvent-responsive 2D morphology of F-OC10 ranging from heptanoic to nonanoic acid was observed. Solvent-responsive 2D morphology of F-OC10 were obtained resulting from moleculesolvent interaction. At high concentrations, the stable alternating and "S" shaped patterns are observed on HOPG interface. When the solution concentration decreases, the monolayer becomes more complex and more structures were discovered. It is reasonable to assume a disparate mechanism for the formation of the interfacial monolayer structures depending on the varying solvent nature, e.g., viscosity, solubility thus the desorption rates, the dielectric properties of the solvent. These results provide insight into the structural variety exhibited by a series of organic molecules and furnish important guidelines to control the morphology by changing the solution concentration and properties of solvent.